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JAPANESE SECRET PROJECTS

During the final years of World War 2, Japanwas desperate for technical advances tocombat the high-altitude B-29 bombers andplanned invasion of the homeland. As citieswere flattened and antiquated aircraft suchas the infamous Zero fighter bravely fought ononly to be shot out of the skies by superiorAllied aircraft, the Japanese military, like theirGerman counterparts, sought innovativedesigns as time and resources drew to aclose.

Japanese Secret Projecls looks in detail atthe multiplicity of aeronautical designs andconcepts that the Japanese developed to tryto counter the Allied onslaught. The book isdivided into two sections dedicated to the airforces of the IJA and IJN with over 42 aircraftexamined in their historical and politicalcontext, each with its variants, performanceand combat records laid out in an easy toread fashion.

Beautifully illustrated by the world's leadingaviation artists, this book is complemented bystunning colour renditions of aircraft incombat including profiles of genuinemarkings and camouflage schemes. Notableemphasis is placed upon the transonicrammer aircraft, strategic long-rangebombers, high-altitude fighters, Kamikazeaircraft and the methods in which theJapanese military adapted Germantechnology to their particular needs such as

the Messerschmitt 262 je| fighter and 163

Komet rocket interceptor. Secret Japanesearmaments are also covered in detail withinformation on guided missiles, aerial rocketsand unique bombs.

With an incredible range of interesting andbizarre aircraft designs and access topreviously unpublished information,Japanese Secret Projects is a gripping andeducational read for aviation and militaryenthusiasts around the world.

Front couer illustration: "Slice & Dice" - Havingslashed their way through the ramjet-equippedP-5 I D Mustang escorts, a pair of Japanese ManshuKi-98 fighter dive on a formation of B-35 flying wingbombers, high over Japan. Although originallyconceived for the ground attack role, the Ki-98 wasone of many fighters developed towards war's endwith the purpose to intercept high-flying allied hearybombers. The Ki-98 in the cover illustration carriesthe markings of the 4th Sentai's 3rd Chutai. Duringthe war the 4th Sentai achieved successes againstB-29 bombers, while fllng their twin-engined Ki-45"Nick" heavy fighters. They utilised both conventionaland ramming techniques to bring down their victims.

This specially commissioned artuork was created byRonnie Olsthoorn - wuw.skyraider3d,com

t24.99us$39.95

cAN$44.95

JAPANESESECRET PROJECTS

EXPERIITENTAL AIRCRAFT OTTHE IJA AND IJN 1939.T945

M IDLAN DAn imprint of

lan Allan Publishing

JAPANESESECRET PROJECTS

EXPERI}IENTAL AIRCR,AFT OFTHE IJA AND IJN 1939.r-945

Edwin 11 Dyer

Japanese Secret Projects: Experimental Aircraftof the IJA and IJN 1939-1945

First published 2009

Reprinted 2010

ISBN 978 1857803 174

All rights reserved. No part of this book may be

reproduced or transmitted in any form or by any

means, electronic or mechanical, includingphotocopflng, recording or by any information

storage and retrieval system, without permission

from the Publisher in writing.

@ Edwin M. Dyer III

Midland Publishing is an imprint of Ian Allan

Publishing Ltd, Hersham, Suney KTl2 4RG.

Printed by Ian Allan Printing Ltd,

Hersham, Suney KTl2 4RG.

Visit the IanAllan Publishing website at

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CopyrightIllegal copying and selling of publications deprives

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At ui*.d sourcesVrrJ **r*:n:ru#ii'tiffiL

6^- w,ts.r! adm,sl{a{tlIaF -L 6 rs. h;rrhdHld*i

Half-title: Profrle art of the ManshuKl-98. PeterAllen

Title page: ManshtrKi-98 in action. Ronnie Olsthoom

Contents

Preface .........6Acknowledgments... ..........7AbbreviationsandGlossary ......8

IJA

KawasakiKi-64.. .......9KawasakiKi-88.. ......12KawasakiKi-91 .. ......14KayabaKatsuodori .....17KokusaiTa-Go. ........20MaedaKu-6 ....22ManshtKi-g8.. ........24MitsubishiKi-73.. ......27NakajimaKi-87.. ......28NakajimaKi-I15Tsurugi............... 31

NakajimaKi-201 Karyu .........34RikugunKi-93... .......37RikugunKi-202.. .......40RikugunKogikenseries . .......43TachikawaKi-74.. .....50TachikawaKi-g4-l . .....53TachikawaKi-g4-ll .....55Tachikawa Ki-162

and other IJA jet projects . . . . . . . . . . . . 59

IJN

KawanishiBaika. ......61KawanishiHllKSoku. .........63KawanishiK-200. ......65KugishOHighSpeedProiects...... .....67KngishoMxY6. ........69KugishdMXYTOka .....70Kugisho MXYS/9 Akigusa/Shuka . . . . . . . .77KugishoR2YKeiun .....78KrlgishoTenga .........81KyushuJTWShinden ..........84MitsubishiGTMTaizan .........91MitsubishiJ4MSenden .........93MitsubishiJ8MSyusui ..........96Mitsubishi-Payen Pa.4OO/Suzukaze 20 . . 101

MizunoShinryull...... .......104NakajimaFugaku .....108NakajimaJlNGekk6. .........112NakajimaKitsuka .....114

Other Aircraft

TheJapaneseRammer. ....... 123

TheKamikazeAirplane .......125MitsubishiT.K.4Type0...... .........126NakajimaAT27 ..... .........127S-31 Kurowashi ..... .........129T.K.19. .......131

Weapon Systems

Japanese Missile and Guided MunitionsProjects.

Specialised BombsSpecialised Bombs: Fu-Go.

Appendices

German Technical Exchange with Japan:ABriefOverview.... .......142

Bibliography. .........150ArtistBiographies ... ......... 151

Ted Nomura HlpotheticalAircraftProfiles .....155

Index

Personalities .........158Aircraft ....... 158

Engines. ...... 160

WeaponSystems. .....160

132

137

139

If you browse any major book seller, you tendto see a good manyworks on the experimen-tal aircraft developed by Germany bothbefore and, particularly, during World War 2.

Also, you'd find a llne selection of books onthe topic of American experimental planes.

From time to time, you could find mention ofsuch 'X-planes' of other nations amongst thetext describing more well known aircraft. Butyou did not often see, if at all, books dedi-cated to Japanese experimental aircraft. Usu-

ally, one had to visit specialty book dealers,hobbv shops, or be fortunate enough to beable to read another language in order to findbooks on the subject of Japanese X-planes.

I was first exposed to the world of Japaneseexperimental aircraft in 1988 through theclassic book Japanese Aircraft of the PacificWar by Ren6 J. Francillon. I found the bookon the shelf in your typical mall bookstore.Sure, before then, I knew about the classicJapanese planes such as the Mitsubishi A6MReisen and the Nakajima Ki-43 Hayabusa. ButFrancillon's book brought to me such planes

as the Nakajima Kitsuka, Mitsubishi J8M

Syusui and the Tachikawa Ki-94.

My interest in military technology sat on thekerb through my college years but afterwardsit slowly ramped back up. I found that I

focused my reading on the military machineof Germany and the sheer breadth of techno-logical innovation their engineers and scien-tists churned out. Small arms, armour,artillery, missiles, submarines, aircraft, rock-etry and much more - no stone was leftunturned by Germany's scientists. It was dur-ing my studies of German aviation that I

would see the Japanese pop up from time totime. Most often, it was the acquisition of Ger-man technology for development in Japan, orGerman plane designs offered for the Japan-

ese to purchase. This piqued my interest inlearning about what the Japanese had brew-ing in their aviation cauldron.

By this time, the World Wide Web wasbecoming the engine of information that it istoday. While I was able to find bits of infor-mation regarding Japanese X-planes, it wasnever anything substantive. Stops into the

Preface

local hobby shop or major book retailers didnot turn up anything above and beyond whatI already knew. I found a rather large gap inthe online data pool on Japanese X-planes, atleast in English, and so I sought about cor-recting that.

In 1998, I began to assemble a websiteinspired by Dan Johnson's Luft '46 whichstarted in 1997 as a one-stop site about Ger-

man X-planes. In 1999, my site, Hikoki: 1946,

went live to the world. During its first fewyears, Hikoki: 1946 expanded to encompass31 Japanese experimental aircraft and sec-

tions on engine specifications, German air-craft the Japanese were interested in orbought, missiles and more. Support for the sitewas great. Such people as artist Ted Nomura,Polish author Tadeusz Januszewski and J-Air-

craft.com contributors Mike Goodwin, George

Elephtheriou and D. Karacay helped the site byproviding both artwork and data on some ofthe planes presented. By 2002, I felt that I'dexhausted what there was on the subject andthe site entered a state of finality with no fur-ther updates having been done since.

Fast forward to the fall of 2007.Jay Slater ofIan Allan Publishing e-mailed me to discussthe prospect of writing a book on Japaneseexperimental aircraft. This was not the firsttime someone had approached me to do so.

But unlike the others, Jay had a well knonmpublisher behind him who had a number ofX-plane books in print, many of which I had inmy own library. It seemed natural to him thata book on Japanese X-planes would be a wel-come complement to their existing titles as

well as providing the English aviation histo-rian or enthusiast with a ready source of ded-icated information on Japanese X-planes. I

certainly agreed.The work you hold is not simply my Hikoki:

1946 website in book form. Yes, some of theaircraft in these pages can be found on thesite but the information here has been furtherresearched and revised. This means the datain these pages is far more up to date than thesite. And for sure, the outstanding artworkprovided makes this a spectacular publica-tion and investment for your library.

6

Because of the constraints on the numberof pages, there had to be a process of select-ing aircraft for inclusion. The planes selectedfor this volume have been chosen based onseveral factors. The first was the nature of theplane in terms of being a conventional or amore radical design. Thus, while the KugishoD3Y Mydjo may be a relatively obscure planeof which only two were built, it was a veryconventional aircraft in terms of design. Thesame applied to the Mitsubishi Ki-83. There-fore, these more conventional designs or pro-totypes received a lower selection priorityover more advanced concepts. Another fac-tor concerned aircraft which were derivativesof established production planes in theJapanese arsenal. As such, designs such as

the Ki-l 16, which was derived from the Naka-jima Ki-84 Hayate, are also excluded. A thirdfactor revolved around the pool of informa-tion available for a certain design. The moreobscure or unknown the design was, thehigher it was considered over other planes.

For example, the scope of the RikugunKogiken designs were of far more interestand of a lesser known nature than the proto-types of the Nakajima G8N Renzan or theAichi S1A Denko of which more informationis readily available. Finally, X-planes thatwere purely research aircraft such as theKawasaki Ki-78, those experimental planes

constructed prior to the start of the war, andmost of the non-combat aircraft (transports,

gliders and the like) were generally excludedfrom contention. Perhaps in a future publica-tion, those designs that did not make the cutfor this book will get their chance.

It may appear that few aircraft remainedwith such pruning but it still left a significantnumber of planes to choose from, from thehistorically important Nakajima Kitsuka andMitsubishi J8M Sy0sui, to more unknowntypes such as the Krlgish6 Tenga and Kawan-ishiK-200.

In so far as the book layout, aircraft are sep-arated by service (lJA and IJN) and thenalphabetised by manufacturer. Those aircraftthat were not of either service (or were jointprojects) are listed last. Missiles and a selec-

tion of some of the more interesting aircraftmunitions that were deployed or were indevelopment are included along with a briefdiscourse on German technical exchangewith Japan before and during World War 2. Afeature in each aircraft chapter is the inclu-sion of a 'Contemporaries' section. The pur-pose of this is to illustrate to the reader thatdesigns didn't occur in a vacuum and similarconcepts could be found in other Alliednations as well as Axis ones. This sectionshould not in any way be construed as point-ing to the Japanese as simply copying thework of other nations. While it is true that theJapanese air forces prior to the war were verykeen on obtaining as much information onaviation technology as possible (and, in somecases, built and flew versions of foreign air-craft), once hostilities began Japan knew shecould no longer rely on outside assistance fortheir aircraft industry and ensured it couldstand on its own. This it did, producing manysuccessful aircraft that were indigenous. Theinflux of German technology during the war

can be viewed as another means by whichJapanese aviation technology was boostedthrough a wartime ally, but more often thannot it was an expediency to rapidly increasethe capability of Japanese aircraft in the faceof aworsening war situation and ever improv-ing Allied fighters and bombers. It is hopedthe information in this section will be a cata-lyst to learn more about the aircraft presentedto expand one's knor,vledge of aviation byother nations. Also keep in mind that this sec-tion does not list each and every plane thatcould be considered a contemporary.Instead, I have picked the more interestingand have intentionally listed only the aircraftname(s) in order to not take away from themain topic at hand. The reader will also findwith certain aircraft a section called 'Sur-

vivors'. Listed here are those aircraft that sur-

vived the war and what their fates were,either being scrapped or escaping the cuttingtorch. Where known, the Hepburn Romani-sation system is utilised for Japanese words.

Every attempt has been made to ensure

accuracy in the information provided in thisbook. Even as the writing of the book wasunderway, I was acquiring additional sourcesand checking and rechecking data to makesure nothing was amiss. Of course, at somepoint I had to 'let it go'. If I held on to chapterswaiting on the next titbit of information toappear, the book would never get finishedand you wouldn't be holding it in your hands.Thus, invariably, there is the risk of omittingsomething, interpreting a translation orsource incorrectly, or iust plain making anerror. To that end, corrections, new informa-tion and any and all comments can bedirected to the author at the e-mail addressbelow.

I hope you, the reader, enloy the book andfind it a worthwhile addition to your library as

a ready resource on some of the most inter-esting Japanese airplanes of the war.

Regards,'

Edwin M. Dyer IIIjapanesesecretprojects@gmail.com

This book would not be what it is without theassistance and support of a good number ofindividuals and I would like to recognisethem here.

First and foremost, Jay Slater and his teamat lan Allan Publishing. It was Jay whoreached out to me and first proposed thisbook and through him it became a reality.

To the artists whose work you will see inthis publication: PeterAllen, Kelcey Faulkner,Muneo Hosaka, Gino Marcomini, TedNomura, Ronnie Olsthoorn and Daniel Uhr.Through their hard work, the aircraft withinthese pages come to life in spectacular fash-

Acknowledgements

ion. To Tim Hortman who graciously pro-vided his photographs of the Kyushu J7W1

Shinden, Nakajima Ki-l 15 Ko Tsurugi and theNakajima Kitsuka currently in store at theNational Air and Space Museum and whichare no longer available to the public.

During the information gathering phase ofthe book, research support and material wasprovided by several individuals. Their assis-

tance helped to confirm or deny data, pro-vided a sounding board for theories, offeredcomments on the information or broughtnew information to the table. These folks are

Shorzoe Abe, David Aiken, Paul Deweer,

Tadeusz Januszewski, James Long, Robert C.

Mikesh, Nicholas Millman, Ronnie Olsthoorn,Masafumi Sawa and Akio Takahashi. As someof the works used in researching the bookwere in Japanese, Ryuki Arceno, NanaeKonno, Lara Law and Tekla Munobe pro-vided translations. For those works in Polish,Michal Sporzyriski was the key translator.

Last but certainly not least, my parents,

Edwin and Margaret, for their support andencouragement. Also to Gail Lashley foralways making sure I had my nose to thegrindstone.

AOAMC Atlantic Overseas Air X{aterial Centre in Nelvatk,

Nerv Jersey.

FE Foreign Equipment. FE numbers were used by

the USMF to mark captured aircraft for tracking

and documentation purposes.

Ha Abbreviation for the Japanese rvord for engine,

hatsudohi. For example, the Nakajima IHa-351

25 l4-cvlinder radial engine. This was used as a

designator for all engines used by the IJA while

the IJN used their own system. Eventually, the

two systems were combined. In the example

above, the '3'was the engine type (14-cylinder,

double+orv radial), the'5' the bore/stloke(130mm/150mm) while the '25' rvas the model

number, taken from the IJN system.

IJA Imperial Japanese Army (Dai-Nippon Teikoku

Rikugun). In this book, IJA refers to the Imperial

Japanese Army Air Sen'ice (Teikoku Rikugun

Kokltai).IJN Imperial Japanese Naq, (Dai-Nippon Teikoku

Kaigun). In this book, IJN refers to the Imperial

Japanese Na'"y Air Service (Dai-Nippon Teikoku

Kaiqun Koku Hombu).

K.K. Stands for Kabushiki Kaisha, which translates

as Company, Limited. For example, Fuji Kokuki

K,K. would be FujiAirctaft Co Ltd.

Ken Abbrel'iationforftensan,meaning'research',

Ki The IJA utilised Ki numbers for aircraft. Ki rvas

the abbreviation for Arlar'which means

'airframe'. The numbet folloling the

abbreviation was the project number for the

aircraft under development regardless of the

manufacturer or aircraft tlpe. For example, the

N'litsubishi Ki-73.

Ku Abbreviation forftakku, meaning'to glide'.

MAMA \'liddleton Air ['laterial Area at Olmstead Field in

tr'liddleton, Pennsylvania. This rvas lvhere

captured Japanese aircraft lvere shipped by the

t]SMF.NA Not Available. In regards to specifications, NA

means that at the time of the book printing, thejnformation on the spec rvas unknown and not

NAS

NASM

Ne

TAIC

available.

Naval Air Station.

National Air and Space N'luseum.

Abbreviation for A'ensfto Rocftello, meaning'burning rocket' in Japanese. Ne r'vas used on

Japanese jet engine designations. For example,

the Ne 330.

Technical Air Intelligence Center located in

Washington DC at NAS Anacostia. This was

rvhere data on enemy aircraft was collected

and maintained. Captured aircraftu'ere

evaluated at NAS Patuxent River, N,laryland.

United States Army Air Force.

Institute. This unit conducted research, design

and development for the IJA. The facilities were

located at Tachikawa.

Shi Beginning in 1931, when the IJN issued a specification

for an aircraft, a shi number was assigned to it,

based on the year of the Showa Japanese

calendar, For example, the \'litsubishi G7M

Taizan was designed to meet the l6-5hi Attack

Bomber specification. 16 stood for Showa 16 or

1 941.

Shimpu The rvord is an alternate reading of the

Japanese franl foi'divine wind' and is used in

this text to describe those aircraft for use by and

for suicide unit missions. Shimprl Tokubetsu

KOgekitai is the IJN designation for suicide

units, meaning Divine Wind SpecialAttackForce. The IJA would use Shimbu Tokubetsu

Kogekitai, shimbu meaning 'band of heroic

ltarriors' or'brandishing a slvord'. Kamikaze is

not used by the Japanese as a description for

suicide units but the word is popular in the

West.

Tochihaua Dai-lchi Rihugun Kohusho First Army Air

Arsenal. IJA air depot that repaired, modified

and distributed aircraft to IJA air units. It also

produced the Ki-30, Ki-43 and Ki-51 in addition

to being one venue for experimental aircraft

development.

Tail Number For the purposes of this book, this refers to

the US Naly method of marking captured

aircraft. It is considered that the number

applied corresponded to shipping allocationnumbers for the aircraft when they wereprepared for transport to the US.

Abbreviations and Glossary

Doi-lchi Kaigun Kaku Gijutsu-sho I st Naval Air Technical ' Rihugun Kohugijutsu Kenkyujo Air Technical Research

Arsenal housed at Yokosuka, Japan. This eroup

rvas responsible for aircraft design fot the IJN.

Dai-lchi Kaigun Koftusho I st Naval Air Arsenal located at

Kasumigaura.

Dai-Juichi Kaigun Ko,ftusho This was the I 1th Naval Air

Arsenal located at the Hiro Naral Arsenal in

Kure, Hiroshima,',vhere seaplanes, flying boats

and engines for the IJN were produced.

Hei Literally'grade C'. Hei is most often used in the

book to describe the third specification, such as

l8+hi Hei.

Hihohi Aeroplane in Japanese.

Jidosha Japaneseforcar/automobile.Koi From time to time, Japanese aircraft i'vould

have Kai appended to their designation rvhen

the design r,as heavily modified but not to a

point it required a nerv designation. Kai meant

'improled'. An example $ould be the Nakajima

Ki-84JI Hayate Kai.

Kaigun Koku Hombu Imperial Japanese Nary Aviation

Bureau of the l\'linistry of the Naty of Japan,

Among a number of duties of this bureau, the

pertinent one for this book ivas the Technical

Depaltment that oversarv the design of nerv

aircraft and equipment.Ko Literally'grade A'. Ko is most often used in the

book to describe the first model of a plane such

as the Ki-l 15 Ko or the first specification, such

as l8-shi Ko,

Koku Hombu Army Air Headquarters. This division of the

Imperial Japanese Army rvas responsible for

research and development of aircraft, aircraft

engines and other aviation equipment. As such,

specifications for aircraft nould be issued fiom

this division.

Kokuhi Aircraft in Japanese.

Klgisho Aircraft designed b1'the Dai-lchi Kaigun KOktl

Cijutsu-sho rvere given the KDgisho designation,

a contraction of KOk[ Gijutsu-sho. One may see

KugishO aircraft called by the Yokosuka

designation but this rvould be incorrect.

Mitsubishi Jnhag'o Kabushihi Kctlsha The full name for

N'litsubishi Healy Industries Co Ltd.

Otsu Literallv'grade B'.Otsu is most often used in

the book to describe the second model of a

plane sur h as lhe Ki-93 Otsu or lhe second

:pecificalion. such as l8-chi 0tsu.

Parh Ridge This rvas the location of No. 803 Special Depot

in Park Ridge, Illinois. Captured aircraft selected

for inclusion in the NASN'l museum rvere stored

here until the collection lvas culled during the

Korean War as the US Air Force needed the

space.

Poul. E. Garber Presenation, Restoratlon. and Storage

Idcili4 Aircraft that sun ived the culling at

Park Ridge rvere moved to this NASN'l facility

located in Suitland-Silvet Hill, I'laryland.

8

USAAF

Imperial Japanese Army

oIo

=

Kawasaki Ki-64

Designers at times relish the freedom to lettheirvisions develop and flow from the draftingboard to the tarmac, ready to take to the skies.Takeo Doi, working for Kawasaki, was justsuch a designer. Despite the very real workdeveloping, testing and producing combat air-craft for the IJA, Doi had a concept that he, onhis own, brought to the fore. Initially, the IJAwould not hear of the design but later, whenthe Ki-64 took shape, their mind would change.

In 1939, Doi was involved with twoKawasaki programs: the Ki-45 Toryu and the

Il,tpERral Jnpafrese ARN4y

Ki-60/Ki-61 Hein. The Ki-45 was proving tobe a horribly troublesome aircraft. Problemswith the landing gear, concerns with drag,engine difficulties and more were provinga thorn in Kawasaki's side. lt was Doi whostepped in to solve the issues plaguing theinitial Ki-45 design. In addition to workingto fix the floundering Ki-45, by 1940, Doiwas involved with the preliminary develop-ment of the Ki-60 heavy fighter and the Ki-61Hein.

Even with such responsibilities, Doi had adesign of his own for a high-speed fighter. Hisconcept incorporated a number of novel fea-

tures which were perceived as ratherunorthodox in comparison to other moreconventional types. Since Koi's aircraft waspurely his own and not created to meet anysort of specification, Koi would be disap-pointed when the IJA forbade Kawasaki giv-ing any further time to the design.

Doi's disappointment then turned to joywhen, in October 1940, the IJA authorisedKawasaki to proceed with developing theKi-64 to meet a requirement for a fightercapable of a marimum speed of 700km/h at5,000m (435mph at 16,405ft) and a 5 minuteclimb to that height.

To power the Ki-64, Doi would enlist the

help of fellow engineers employed by the

Akashi engine plant. The decision was made

to use the Kawasaki Ha-201 ([Ha-72] 11)

engine. This was actually a combination oftwo Ha-40 engines, the Ha-40 being the

licence-built version of the Daimler-BenzDB601A. Each Ha-40 was a 12-cylinder, liq-

uid-cooled powerplant and the Ha-201 was

formed through having one engine in front ofthe cockpit and the second behind it. The rear

engine drove the first of the contra-rotatingpropellers and it had a variable pitch' The

front engine drove the second propeller,

which was of a fixed pitch. Both propellers

were three-bladed. All told, the Ha-201 was

expected to produce 2,350hP.

The use of the Ha-201 was not the most

novel feature of the Ki-64. Itwas the means ofcooling the engine that was notable' The

Ha-201 was to be cooled by a steam con-

densing system. A tank of 15.4 gallons ofwater was fitted into each wing and the outerwings and flaps seled as the cooling surface,

totalling 23.99m' (258.3ft'). The port wing ser-

viced the front engine while the starboard

wing provided coolant to the rear engine. As

the water coolant turned to steam, it waspumped out into the wings where the steam

would condense back into water which inturn was pumped back into the engine. The

main benefit of this system was lower drag on

the airframe as the need for air inlets was

removed or minimised. Each laminar flowwing housed the fuel tanks and one 20mm

Ho-5 cannon while two more were fitted inthe fuselage deck. One drawback to the

wings being packed with the cooling system

apparatus was that it left little room for the

fuel tanks and consequently the Ki-64's oper-

ational range suffered. The majority of the

fuel was carried in the fuselage, the tanks

being placed in and around the space left

available by the Ha-201 engine. The main fuel

tank was situated in front of the cockpit, hold-

ing 306.7 litres (81 gallons). Under it was the

oil reservoir, holding 79.5litres (21 gallons) ofoil for the engines. Behind the cockpit were

two coolant tanks holding 83.3 litres (22 gal-

lons) and 117.4 litres (31 gallons) respec-

tively. The smaller serviced the front engine,

the larger the rear engine.Doi tested the Ha-201 and the cooling sys-

tem to a considerable degree. In 1942, one ofthe Ki-61 Hein fighters was specially modified

to test the cooling method and its trial flights

began in October 1942 and ran through to the

end of 1943. Because ofthis thorough testing,

the construction of the Ki-64was delayed and

so did not reach completion until December1943. Nevertheless, Doi was satisfied that the

cooling system would grant an additional41km/h (25mph) to the Ki-64 and battle dam-

age would not significantly reduce the effec-

tiveness of it and as such the exhaustive

testing was worth the effort.

With the Ki-64 complete, flight testing com-menced in December 1943. Four test flights

were successfully made without mishap.

However, on the fifth, the rear engine caught

fire. The test pilot was able to land the aircraft

and the fire was quenched. Mechanics

stripped the engine out of the Ki-64 and

returned it to the Akashi plant for a full repair.

The Ki-64 itself was returned to the city of Gifu

which, at the time of World War 2, was a

major industrial centre.Plans were made to improve the Ki-64 by

replacing the 2,350hp Ha-201 '"vith an

enhanced model that could generate up to2,800hp. The propellers '"vould be replacedwith two, constant-speed contra-rotating pro-

pellers that were electrically operated. It was

envisioned that with these modifications, the

Ki-64 Kai would be able to attain a top speed

of 800km/h (497mph).

Unfortunately for the Ki-64, repair work lan-

guished, especially in the face of more press-

ing needs for the Japanese arms industry and

the production of more conventional aircraft'

As a result, both the Ki-64 and the Ki-64 Kai

were cancelled. After Japan's surrender, the

Ha-201 was still at Akashi, its repairs incom-plete. When US forces arrived in Gifu, the

Ki-64 was found and technical teams gutted

the airplane of its cooling system. The system

was then crated and shipped to the UnitedStates for study at Wright Field in Dayton,

Ohio.Given the relatively long development time

of the Ki-64, US intelligence had already

become aware of the design. Thus, expectingthe Ki-64 would see service, the airplane was

assigned the codename RoLr.

Kawasaki Ki-64 - data

Contemporaries

Republic XP-69 (US), Heinkel P.1076 (Germanv), Caproni CA l83bis

(ltal.v)

Powerplant

One Kauasaki Ha-201 (lHal2l I l), 24-cvlinder. inverted'V. liquid'

cooled engine developing 2,350hp at take'off, 2,200hp at 12,795it, driving

tlro, metal, 3-bladed contra-Iotatins pr0pellers

Fighter

0ne

Tlpe

Crew

Dinensions

Span

Length

Height

Wing area

lVing loading

Pouer loading

13.48m 44.2:t

ll.00m 36.lft

4.24m 13.9ft

28m' 30l,3ft'

3.471b/m' 37,31b/ft

2,17ksihp 4.8lbihp

Weights

Empt)

Loaded

1,050kg

5, t00kg

8,929Ib

1 1,244Ib

Performance

\'lar speed

Range

Climb

Ceiling

Fuel capacit,v

690.3km/h

at 5,000m

l.000km

12,000m

618 liires

429mph

at l6,40ift

62lmiles

39,370ft

136 gallons

5 min 30 sec to 5,000m (16,405ft)

Armament

Tn'o 2Omm Ho-5 cannons in the fuselage deck, one 20mm Ho-5 cannon

in each ning

Deplolment

None. Onlv one Ki.6.l rras completed and flolvn before lhe end of lhe

l0 hpnnEss Stcner PRo;tcrs: ExpsRrN,reNrar- AIRcnant oF rHE IJA AND IJN 1939-1945

ooz-

l1I[,tpsRrer- JnpanEsE Anuy

Kawasaki Ki-88

\r\

In August of 1942, the IJA saw a need for a air-

craft that, in its primary role, would selve as

an interceptor flying sorties to defend instal-

lations, airfields and other assets that wereconsidered important and therefore subjectto enemy attack. Design specifications weredrafted by the IJA for the aircraft and it wasKawasaki who put forth what they felt wasthe answer: the Ki-88.

Prior to drafting their design specifications,the IJA had sifted through a number of ideas

before settling on a plane that had to have a

hear,y armament to ensure it could inflict sig-

nificant damage to enemy aircraft, especiallybombers, and also good handling character-istics to make it not only a stable gun plat-

form, but also to avoid a steep learning culefor new pilots.

To this end, Tsuchii Takeo, a designer for

Kawasaki, began work on what wouldbecome the Ki-88. Takeo selected a 37mm

cannon as the primaryweapon, supported by

two 20mm cannons. lt is probable that the

37mm Ho-203 cannon and two Ho-S 20mm

cannons would serve as the armament fit

with all three weapons fitted in the nose'

Given the size of the Ho-203 (which was a lit-

tle over 1.53m (5ft) in length, weighing 88.9kg

( 1 96 lb)), this presented a problem in squeez'ing them, along with the engine, into the

nose. To get around this, Takeo placed the

1,500hp Ha-140 liquid-cooled, turbo- (or

super-) charged engine in the fuselage,

behind the cockpit. The three-bladed pro-

peller was driven using an extension shaft

that ran from the engine to a gearbox con-

nected to the propeller. In essence, Takeo

built the aircraft around the Ho-203.

The main advantage of placing the engine

in the fuselage was that it allowed the cannonto fire through the propeller hub, producing a

more stable firing platform that resulted inimproved accuracy. Another advantage wasthat it allorved a skilful designer to make the

nose more streamlined, enhancing speed

performance.A good number of references infer that

Takeo's design rvas inspired by the Bell P-39

Airacobra. While there is no evidence that

specifically states that Takeo simply copiedthe American fighter, the P-39 was in limitedoperational use by the time design workbegan on the Ki-88 in 1942, notably seeing

action in the Battle of Guadalcanal. Thus, the

Japanese were aware of the design. Whetheran example was ever captured for analysis is

unknown but certainly intelligence was avail-

able on the plane. Or, it may be that Takeo

arrived at the same conclusion as did H'M.

Poyer, designer of the P-39, when looking at

how best to accommodate a large calibrecannon in a single engine aircraft.

In June of 1943, Takeo finalised his design

for the Ki-88. Apart from the use of a 37mmcannon and the engine placement, the Ki-88

bore no further resemblance to the P-39. The

Ki-88 had a deep fuselage to accommodatethe Ha-l40 engine that was situated belowand to the rear of the cockpit. The air scoop

for ihe Ha-140's radiator was mounted on the

bottom of the fuselage, iust forward of the

wing roots. The radiator itself was positionedback from the scoop on the bottom interior ofthe fuselage, almost directly underneath the

pllot's seat. Jutting out on the left side ofthe fuselage, iust above the trailing edge ofthe wing, was the scoop to provide air to the

turbo- or super-charger of the Ha-140' The

landing gear was conventional and the maingear retracted into the wings, while the tailwheel was fixed. A fuel tank was provided in

each wing, mounted behind the wheel wells'On either side and to the bottom of the

Ho-203 cannon were the Ho-5 cannons.

With the final design comPlete, workbegan on a full scale mock-up of the Ki-88 and

this was completed sometime in 1943' Inaddition, work had already begun on con-struction of the fuselage and wings for a pro-

totype and it was expected that by October

12 hpaNlesn Sscner PnotEcrs: ExpERIMeN-taL AtRcRant op rHE IJA aNo IJN 1939-1945

1943 the Ki-88 would be nearing completion.The IJA, however, had other plans for theKi-88. After inspecting the mock-up and inreviewing the projected performance data ofthe plane, it was seen that it offered no realadvantage over other designs then in opera-tional use, notably the Kawasaki Ki-61 Hien.Thus, Kawasaki was ordered to terminate allwork on the Ki-88.

Kawasaki Ki-88 - data

Contemporalies

Bell P.39 Airacobra (l.S), Bell XFL-l Airabonita (trS). Bell P.63 King

Cobra INATO codename lrcd in Russian senice) (LS), Cudkov Gu-l

(Russia)

,:4 ura"e . ffi

t t{i'W.'' ,h "i " r-.l'

" b"' ',1'J "" ry i"T "5#*;ffi{:s*J

E

z

irrt"q,

...€*'.Tiyb*)\

Tlpe

Crew

lnterceptor

0nc

Porverplant

Onc Kau,asaki Ha-110, liquid-cooled. turbo, or supercharged engine

devcloping l.j00hp diiving a three.bladed propeller

'irT,\u"s4NLt.

! :,;*.: ;\

.i .,* * Ss "*

Dimensions

Span

Length

Height

\\iing area

12.37m

l0.l8m

1.1{m

27.19m'

40.6it

33,4ft

r3.6ft

26911

IYeights

Emptv

Loaded

2,9.19k9

3,899ks

6,5031b

8.598Ib

Performance (specifications arc estimations bl Kau,asaki)

\'lar speed at 19,6851t 600kmih 373mph

Range

Climb

Ceiling

t,198km 715 niles

6 min 30 sec to 5.000m (16.{0.lft)

I 1,000m 36,089ft

fumament

One 37mm Ho.20ll cannon and tn'o 20mm Ho-5 cannons

Deplolment

None. The Ki-88 did nol progress past a mock.up and partlallv

completed prolot!pe.

IltptRra,r- .llpnrussE ARn'rv l3

Kawasaki Ki-91

oEoz2

222s

This story centres on the failure of a bomberthat inspired the development of anothernew type. The Nakajima Ki-68 and the

Kawanishi Ki-85, both four-engine, long-

range bomber designs, hinged on the success

of the IJN's Nakajima G5N Shinzan (Mountain

Recess). The G5N would prove to be a failureand in turn led to the termination of the Ki-68

and Ki-85 programs; therefore the IJAwas leftwithout a long-range bomber project. It wasKawasaki who stepped in to fill the gap withtheir own design.

In 1938, the IJN was enamoured with the

idea of a bomber that was capable of operat-

ing up to 6,486km (4,030 miles) from its base.

In part, this was due to the initial desire tostrike targets deep in Russia from Manchurianbases. Later, when Japan went to war withthe United States, a need to attack the US

mainland was identified and it was recog-

nised that a two-engine design would not suf-

fice - four engines would be required. On the

understanding that the Japanese aircraftindustry had very little experience in buildingsuch aircraft, the IJN used the Mitsui Trading

Company as a cover to acquire a Douglas

DC-4E four-engine airliner, ostensibly for use

by Japan Air Lines. The development of the

DC-4E four-engine passenger aircraft wasfunded by five airlines and Douglas withUnited Airlines building and testing the oneprototype. While the DC-4E was impressive,

in terms of its operating costs it did not add

up. The aircraft was complex and this

resulied in maintenance issues, whichincreased the cost of using the plane. Support

for the DC-4E'"vas withdrawn and Douglas

'uvas asked to simplify the design. As a conse-quence, the DC-4 sarv operational use withthe US Army as the Douglas C-54 Skymaster.

In earlv 1939, the sale of the DC-4E wascompleted and arrived in Japan to be

reassembled. By this time, the IJN had

informed Naka.iima to be ready to study the

DC-4E to produce a suitable bomber devel-

opment from it. After having been flown sev-

eral times, ihe DC-4E rvas then reported as

having'gone down in Tokyo Bay', but in real-

ity had been handed over to Nakajima whoseengineers took it apart. Within a year, Naka-jima had built the prototl,pe G5N1 which first

flew on 1 0 April 1941 . The G5N 1 used only the

landing gear layout, wing design and radialengine fittings from the DC-4E coupled to anew fuselage, tail design and a bomb bay.

The IJA planned to produce the G5N1 and

a.3

Nakajima submitted the Ki-68 version usingeither the Mitsubishi Ha-101 or NakaiimaHa-103 engines in place of the NakaiimaNKTA Mamoru 11 units on the G5N1. Kawan-ishi also submitted their Ki-85 which was touse the Mitsubishi Ha-111M engines.

As it was, the GsNl proved to be a dismalfailure. The NKZA engines were problematicand underpowered and the aircraft was too

hear'y and complex. These difficulties con-

tributed to the overall poor performance of the

G5N1. Despite the problems, three more G5N1

aircraft were built followed by a further two air-

craft that replaced the NKTA engines for fourMitsubishi Kasei 12 engines. The two addi-

tional aircraft were designated G5N2, but even

the Kasei 12 engines could not resuscitate the

design and the problems remained. Due to its

complications, the G5N1 was never used as a

bomber. Two G5N1 (using Kasei 12s) and twoG5N2 aircraft were converted to transports and

serued in this role until the end of the war. The

Allies gave the G5N the codename lz.By May 1943, the cancellation of the G5N

had also brought the demise of both the Ki-68

and the Ki-85 (of which Kawanishi had amock-up constructed by November 1942),

leaving the IJA with no active four-engine

-r1.s.t

*t1

14 JapnNesn SEcRET PRo:Ecrs: ExprRrurural AtRcRnlr op rHE IJA a.Nl IJN 1939-1945

oEozz

oType

Crew

Kawasaki Ki-91 - data

Contemporaries

Focke-Wulf T0 'Transozean' Projekt B [Germany), Focke.Wull Frv l9l C

(Germany), Focke-Wulf Fw300 (Germanl)

High-Alttude, Long-Range Bomber

EEht

Powerplant

Four Milsubishi Ha-214 Ru, I 8-oiinder, supercharged radial engines

developing a mariimum of 2,500hp; each engine to drive a fouFbladed

propeller

,6tr\Dimensions

Span

Length

Height

Wing area

47.9m

32,97m

9.99m

223.99m

157.4ft

l08.2ft

32.8fr

2,41Lt lft: &6Weights

Empiy

Loaded

33,999k9

57,999k9

74,955 1b

127,865Ib

Range

Climb

Ceiling

Speed

Max speed ;80kn-/h 360mph

at 9,808m at 32,180ft

9,000 to I 0,000km 5,592 to 6,2 1 3 miles

20 min 30 sec to 8,000m (26,246f1)

13.500rn 44,291ft

Armament

Tweh'e 20mm cannons, two cannons each in one offour turrets located

in the nose, underside of lhe fonvard fuselage and top and bottom 0l

the aft fuseiage respectively. A fifth tunet mounted the remaining four

cannons. Standard bomb load 4,000kg (8,816tb) (perhaps up to 8,000kg

(1 7,636 lb) for shorter ranged missions)

Deployment

None. Prototlpe 60 per cent complele by the end ofthe war

bomber designs on the table. Kawasaki, see-ing the opportunity, immediately got to workon designing a new bomber. The man behindthe Ki-91 was Takeo Doi, an engineeremployed by Kawasaki. It was his goal to seethe development of a successful four-engine

Il,IpEntaL JnpnrussE ARnrv

bomber and engineer Jun Kitano would workwith Doi to help turn the aircraft into reality. InJune 1943, Doi and Kitano began their initialresearch and by October, work on the firstdesign concept for the Ki-91 was underway.

The Ki-91 was slightly larger than the Boe-

ing B-29 Superfortress which was to be massproduced in late 1943. Four MitsubishiHa-21418-cylinder radial engines were chosen topower the Ki-91. As the plane was expectedto operate at high-altitude, provisions weremade to utilise superchargers with the

l5

engines and the projected maximum speedwas 580km/h (360mph). To provide for theanticipated 10,001km (6,214 mile) range,each wing carried eight fuel tanks with a fur-

ther two mounted in the fuselage above thebomb bay. For weapons, the Ki-91 was tocarry a hea'uy armament of tr.t elve 20mm can-nons. Five power-operated turrets were to beused; one in the nose, one on the undersideof the forward fuselage, one above and belowthe aft portion of the fuselage, and the last inthe tail. The bottom turrets were remotelycontrolled while the remainder weremanned. The tail turret was to mount fourcannons while the rest had two cannonseach. As far as bombs, a total payload of4,000kg (8,8181b) was envisioned and theKi-91 was to have a tricycle landing gear withthe nose gear using a single tyre and the mainlanding gear using dual tyres. A semi-recessed tail wheel was also installed.

Another feature of the Ki-91 was to be the

use of a pressure cabin for the eight mancrew. But the development of such a largepressurised cabin for the Ki-91 was expectedto take some time to implement, even usingknowledge from another of Doi's designs, theKawasaki Ki-108, a twin-engine high-altitudefighter fitted with a pressure cabin for thepilot. Therefore, it was decided that the initialKi-91 prototype would be built without pres-

surisation so as to avoid holding up develop-ment and allow its flight characteristics to bemeasured. Once the pressurised crew cabinfor the Ki-91 was ready, subsequent aircraftwere to have it installed.

In April 1944, a full-scale wooden mock-upwas completed and Kawasaki invited IJA offi-cials to come and review the Ki-91. Up untilthis time, the project was a private venture byKawasaki to which considerable companyresources has been allocated. lf the IJA didnot find the bomber to their liking, it wouldhave been a waste of time, effort and money.Fortunately, the IJA saw potential in the Ki-91

and work continued. In May, the IJA

inspected the Ki-91 mock-up and immedi-ately ordered production of the first proto-type. Kawasaki planned to construct theKi-91 at a new plant in Miyakonojo inMiyazaki Prefecture. However, the IJAdid notwant to wait for the construction of a newplant and directed Kawasaki to use theirestablished factory in Gifu Prefecture. By

June 1944, the construction of the prototypeKi-91 had begun at the Gifu factory, togetherwith the necessary tools and jigs to producefurther aircraft.

However, June would see the first B-29

raids over Japan, but as the attacks were fewand far between, work on the Ki-91 continueddespite the worsening situation for the coun-

try. This would change by the close of 1944

when B-29s began to operate from the Mari-ana Islands and by 1945 bombing raids werefar more frequent. In February 1945, a raidheavily damaged the factory in which theKi91 prototype was being constructed. Thedamage was extensive, ruining the tools andjigs. With the loss of equipment needed forfuture production coupled with dwindlingsupplies of aluminium, the IJA decided thatfighters to combat the marauding B-29s hadbecome a higher priority than bombers. Anyhope of utilising such bombers was at bestslim. With the Ki-91 at 60 per cent comple-tion, Kawasaki stopped further work on thebomber and the project was officially can-celled in February 1945.

Had the Ki-91 achieved service, plans toattack the US mainland were in place to oper-ate the bomber from the Kurile lslands usingtemporary bases, while another plan to strikeHawaii was formulated using bases in the Mar-

shall Islands. The second plan was renderedobsolete when the Japanese lost the MarshallIslands to the Allies in February 1944. As a note,contemporary images sometimes show theKi-91 as having a bomb bay battery of down-ward firing cannons for a ground-attack role.While the Japanese were interested in suchconcepts, there is no evidence that Kawasakienvisioned such a task for the Ki-91.

Ecz

l6 JnpanesE SrcnEr Pno:Ecrs: ExpeRttteNrnt- AtRcRnrt op rHE IJA AND IJN 1939-1945

Kayaba envisioned that his design for a fast,point defence interceptor would sweepthrough the Allied bombers like the kat-suodori bird hunts for fish. Impressed with theprowess of the katsuodori, Kayaba named hisdesign after the bird. But as we will see, hisvision was to meet with a harsh reality.

The genesis of the Kayaba Katsuodoribegan as far back as 1937 with the KayabaRamjet Study Group, a collection of engineersand scientists who sought to investigate ram-jet propulsion in Japan. The concept of theramjet was actually patented in 1908 byFrench engineer Ren6 Lorin, but it was theRussian I. A. Merkulov who first built andtested one, the GIRD-04 in 1933. A ramjet is avery basic engine with few moving parts. Insimple terms, it uses the high pressure airgenerated by the aircraft's forward motionand forces it through the inlet. The air is thenmixedwith combusted fuel-this heats the airand is forced out of the rear of the engine, pro-viding forward propulsion. Unlike pulsejets(which were to be used on the KawanishiBaika, see Page 61), the fuel flow is continu-ous. Without getting into the specifics of aramiet, adjustments in the design of the inlet(to maximise the intake of air), combustor (toensure effective operation during flight move-ments) and the outlet nozzle (to effect accel-eration increases) all come into play on

Itr,rpsnral JapaNssE AnN,ry

Kayaba Katsuodori

designing such an engine. The main draw-back with a ramjet engine is that at subsonicspeeds its performance is poor. Below6l2km/h (380mph), a ramjet suffers signifi-cant loss in speed and becomes highly ineffi-cient in terms of fuel consumption. Theramjet typically requires another powersource to bring the aircraft up to the speed atwhich the ramjet can operate efficiently. Typ-ically, this speed is at least 966km/h(600mph). Once the ramjet reaches thatspeed the engine is self-sufficient and, with-out fuel injection moderation, would propelthe plane to speeds far in excess of thedesign's ability to handle the high tempera-tures and Mach number.

The Kayaba Ramjet Study Croup saw thebenefits of high speed with a relatively easy tomanufacture engine. The group producedtwo test models before the final product, theKayaba Model 1 ramjet, was realised. TheModel I was projected to be able to offerspeeds of 900km/h (559mph). With theengine complete, all thatwas neededwas theaircraft to fit it into.

The airframe design began with KumazoHino. Hino was an officer in the IJA and hadbeen the first Japanese to unofficially make aflight on 14 December 1910 when he acci-dentally took to the air in a Hans Grade mono-plane while he was taxiing. This aircraft had

The Katsuodori depicted here is shown in thecolours and markings of the Tlst Sentai. It isintercepting TolryGbound Nonhrop B-35 bombersof the 44th Bomb Squadron, 40th Bomb Groupoperating from Tinian.

been purchased from Germany. His interestin aviation saw him produce four aircraftdesigns: the Hino No. l, No. 2 and the No. 3

and No. 4 Kamikaze-go airplanes. However,each of these designs was a failure. Pressurefrom his military superiors saw Hino give upon aviation by 1912.

However, in 1937, Hino was inspired to cre-ate a tailless glider. The project was takenover by the Kayaba Seisakusho (Kayaba Man-ufacturing Works) and then by Dr. HidemasaKimura who worked for the AeronauticalResearch Institute of the Tokyo Imperial Uni-versity under Dr. Taichiro Ogawa. The resultwas the HK-l. The HK-l (standing for HinoKumazo) was built by the lt6 Hikoki K.K. andwas completed in February 1938. lt waspurely a research glider to test the taillessconcept. Testing commenced in December1938 with ground towing at Kashima inIbaraki Prefecture and the first air releasedflights began in September 1939 at Tsu-danuma in Chiba Prefecture. Because itshowed positive results, the IJA took an inter-est in the concept. The HK-l was purchasedby the Rikugun Kokugijutsu Kenkyujo in April

zooFJoazzo

17

1940 for continued testing. However, a subse-quent test flight on 16 April by an IJA officerpilot resulted in a hard landing that damagedthe HK-l beyond repair. In all, 182 flights had

been made in the HK-1.

With the UA still interested, the Rikugun

Kokugiiutsu Kenkyujo set aside 200,000 yen

to continue the project. Kimura, along withKayaba's chief development designer Dr.

Shigeki Nait6, set about the task of producinga new tailless aircraft, this time with a possi-

ble military application. The result was theKu-2. The Ku-2 had no tail but rudders werefixed to the wing tips and the design wastested extensively from November 1940

through to May 1941 making 270 flights in all

before it was damaged in a crash on l0 May.

To further test the concept, Kimura (with the

aid of J6iiWashimi) produced the Ku-3whichhad no vertical control surfaces at all and fea-

tured a cranked delta wing form to test vari-

ous angles of sweep. The only control camefrom the flaps arranged along the wings. 65

flights were carried out with the single Ku-3

before a crash in 1941 wrecked the glider.

The last design put forward by Kimura wasthe Ku-4. At the request of the RikugunKokugijutsu Kenkyujo, the Ku-4 was to bepowered and a rear mounted 120hp de Hav-

illand Gipsy 4-cylinder, air-cooled, inlineengine was selected, turning a two-bladedpropeller. Unfortunately for Kimura, the IJA

lost interest in the entire concept. With theloss of the Ku-2 and the Ku-3, the IJA can-

celled the Ku-4 before it could be finished.With no backing, Kayaba could not afford the100,000 yen to finish the Ku-4 alone. The IJA

had paid Kimura and Kayaba 17,000 yen outof the 200,000 yen project money for costsassociated with the Ku-2, Ku-3 and what wasalready paid into for the Ku-4. The remainingfunding was not released. Shiro Kayaba, how-ever, still had hopes that the concept could bea potent weapon and from this came the Kat-

suodori.The roots of the Katsuodori come from the

Ku-2. Unlike the Ku-2, the wings were movedhigher on the fuselage and the wing form had

a rearward sweep. The Katsuodori retainedthe vertical wingtip rudders used on the Ku-2.

The ramjet filled most of the fuselage whichmeant there was no room for landing gear.

Instead, a main skid was incorporated on the

underside of the fuselage along with a smallwheel mounted at the rear of the aircraft.

Without integral landing gear, the Kaisuodorirvas to be fitted with a simple, sprung set oflanding gear that could be jettisoned whenthe aircraft took to the air. The pilot sat

towards the front of the fuselage and was pro-vided with a one piece canopy that offeredrespectable visibility to the front and sides.

In order to get the Katsuodori off theground, Kayaba envisioned the use of fourrocket booster units. Secured to each side ofthe fuselage under the wings were two rocketunits and together all four could provide an

estimated 7,200kg (15,873Ib) of thrust. Theplanned procedure for using the rockets wasto have one on each side being fired first, andwhen these had burned out the next pairwould be fired. Each rocket contained pro-pellant for five seconds ofthrust and, all told,the scheme would give the Katsuodori a totalof ten seconds of thrust with which to get theplane off the ground and the ramjet function-ing. Kayaba estimated that the Katsuodoriwould need to achieve 367km/h (228mph)

before the ramjet would operate and cer-

tainly the speed provided by the rocket unitswould have been sufficient for this to happen.The rockets, once used, may or may not have

been releasable but the latter is likely in orderto minimise drag.

With the ramjet operating, the estimatedperformance of the Katsuodori was a speed

of 900km/h (559mph) and a climb rate ofthree minutes to reach an altitude of 10,000(32,808f1). Fuel load was 1,500kg (3,306lb)

and with a fuel consumption of 50kg (1 l0 lb)per minute would grant a combat enduranceof thirty minutes. Once the fuel wasexhausted, the Katsuodori would use its glid-ing properties to return to base.

For weapons, Kayaba planned on mount-ing two 30mm cannons externally, one undereach wing near the wing root. Kayaba did notwish to use existing 30mm cannon designssuch as the Ho-155 preferring to produce a30mm version of the 40mm Ho-301 cannonwhich his manufacturing facilities were con-structing for use in the Ki-44-ll Hei Shokifighter. The Ho-301 used caseless ammuni-tion with each round being, in effect, a rocket.The propellant cavity was partially lined witha thin aluminium cap. When the primer wasstruck, the propellant was ignited and thepressure would build up until the cap burst,the exhaust gas being vented out the back ofthe round to move the projectile forward. The

main advantage of the weapon was its lightweight for such a heavy calibre.

The design of the Katsuodori was nearlycompleie by 1943 and Kayaba anticipatedthat he could have had a flying prototype by1944. By this time, however, the IJA wasalready involved with the rocket poweredKi-200 (the IJA version of the IJN's MitsubishiJ8Ml Syusui - see Page 96) and so paid noattention to the Katsuodori. Kayaba, in tryingto salvage the design, stated that he couldadapt the Katsuodori to accept the Kugisho

Ne20 turbojet or the KRl0 rocket motor as

used in the Ki-200. And since his design was

l8 JepeNosn SEcRET PRoJECTs: ExpERTMENTAL ArRCRarr oF rHE IJA aruo IJN 1939-1945

z,ll:

F

L

nearly complete a protot,?e Katsuodoricould be ready for testing before the Ki-200.

The advantages ofthe Katsuodori includeda ramjet that was far less complex to con-struct than a turbojet. This would have beena critical asset in a Japanese war industry thatwas devastated by US bombing. It could alsouse standard aviation fuel, unlike the Ki-200

that required special fuels, and by extension,could operate from any airfield without theneed ofspecial fuelling apparatus and proce-dures. While the speed of the Katsuodoriwason par with the Ki-200, the Katsuodori's com-bat endurance was far superior to the Ki-200and the IJA's own planned rocket intercep-tor, the Rikugun Ki-202 Syusui-Kai (see Page40).

However, the Katsuodori had several draw-backs. The first was the use of the rocketboosters to get the plane up to speed. TheJapanese did not have a successful track

record for using such units. Improper place-ment of rocket boosters was the reasonbehind the aborted second flight of the Naka-jima Kitsuka (Page 114), heavily damagingthe aircraft. Attempts to use rocket boosterson the Mitsubishi Ki-l09 to boost take-off andclimb met with such poor results that therockets were removed from the Kil09 devel-opment all together. A misfire or variation inthe thrust output might result in the planecareering out of control. Like the Ki-200, oncefuel was exhausted the Katsuodori lost its

speed advantage, and on the ground itsrecovery would take longer since the Kat-suodori could not move on its own withoutmeans of wheeled apparatus. This made itr,ulnerable to intruder aircraft dedicated toairfield interdiction missions. Kayaba's elec-tion to use a 30mmversicln of the Ho-301 can-non would have been a recipe for disaster.The 40mm version, as used in combat by the

Japanese, had an incredibly short range -only 149.5m (490ft) since it had a muzzlevelocityof 241mlsec (79OfVsec). Coupling thevery short range of such a weapon with a highclosure rate due to the speed of the Kat-suodori against a slow bomber, the pilotwould have had mere seconds or less to lineup the target, fire, and then bank to avoid col-lision. Since Kayaba did not proceed with a30mm variant of the Ho-301, the muzzlevelocity for the round is unknown but it can-not have been substantially more than theHo-301.

Despite the potential advantages over theKi-200, the Katsuodori would never see lifeoutside plans on Kayaba's design board. TheIJA was looking to the Ki-200 and their ownKi-202 for their interceptor needs and thusended Kayaba's dream of seeing his Kat-suodori taking to the skies to defend Japan.

Ihyaba Katsuodori - data

Contemporaries

Handley Page H,P.i5 Mam (tiK), B0K-5 (Russia), Blohm undVoss

P.210/P.215 (Germany), Heinkel P.1078 (Germany), NorthropXP-56 Black

Bullet (US), Northrop XP-79 Flying Ram (US), Skoda-Kauba SK P,14.01

(Cermany), Lippisch Li P. I 3a (Germany), l'lesserschmitt Me P.l l0l L

(Germany), Heinkel He P,1080 (Germany), St0ckel Rammschussjiiger

(Cermany), Leduc Model 010 (France), Kostikov 302 (Russia)

Point Interceptor

0ne

Powerplant

One Kayaba Model I (or possibly later) ramiel producing 300kg (661 Ib)

ofthru$ at 367km,rir (228mph), 420k9 (925 Ib) of thrust at 490kn/h

(304mph), 550kg (1,212 lb) of thrust at 6i 2kny'h (380mph) and 750kg

(1,653 lb) ol thrust at 734knr/h through l,l03kffi (456mph through

685mph)

Type

Crew

Dimensions

Span

Length

Height

Wing area

Wng su'eep

8.99m

4.48m

1.85m

12.57m'

25.5"

29.5ft

I 4.7fr

6.lfr

l35.4fr:

Weights

Empty

Loaded

850k9

3,000kg

l,873lb

6,613 lb

Perfonnance

Max speed

Landing speed

Range

Climb

Ceiling

900knt/it 559mph

l00krdl' 62mph

400km 248miles

3 min to 10,000m (32,808ft)

15,000m 49,21211

Armanent

Two 30mm cannon

Deploynent

None. The Katsuodori did nol advance beyond the drawing board.

IMprRr.q.L hpnNEse Annv l9

zcoIFJoezzo

The profile depicts the Kokusai Ta-Go prototypein the colours it actually sponed.

Kokusai Ta-Go

In 1943, the Allied island-hopping campaignwas underway and in 1944 the Japanese

would see their island outposts, bases and

strongholds destroyed and lost to them for-

ever. In 1945, the Japanese lost their holdingsin Burma, Borneo, Iwo Jima and Okinawa.Japanese military planners had no doubts

that the Allies would continue their progress

and land forces on the main islands of Japan.

The Allies did indeed have such a plan knorvnas Operation Dovmfall. The Japanese, todefend against the invasion they felt wascoming, put into motion Ketsugd Sakusen orOperation Decision.

Operation Decision's main componentwas the use of shimpu and shimbu missionstargeting the Allied naval force, specificallylanding craft, troop ships and support ships.

To repel the invaders, all manner of craftwere assembled for the Japanese defender ofkokutai, the national polity of self sacrifice.

Midget submarines such as the Kairyl, Koryland the crude U-Kanamono, the Kaitenhuman torpedo, small explosive ladenpowerboats like the Maru-Ni (lJA) and Shinyo(lJN), and even frogmen (the Fukuryu) wereprepared for the final showdown. Even thebest tanks, the Type 3 Chi-Nu and Type 4 Chi-

To, were held in Japan to counter Alliedarrnour. Aircraft would also play a significantrole in the defence of Japan. Itwas estimatedthat 10,000 aircraft of every type would be

available to throw at the Allied invasion fleet.

It was thought that the mass wave tactics

would result in a tremendous loss of aircraftwhich the Japanese industry in 1945 wouldbe unable to keep pace with unless steps

were taken to remedy such a situation. The

Ta-Go was one such remedY.

By 1945, Japanese industries were underregular bombardment from US airpower. In

addition to war factories being razed to theground, Japan was being starved of materialsneeded to sustain weapon production. Alu-minium was a key material in aircraft pro-

duction and it was estimated that byDecember 1945, even with strict control, the

supply of this metal would be exhausted.

Consequently, wood was to become the

main material for aircraft construction,regardless of the type of aircraft concerned.Examples included the Tachikawa Ki-l06 (a

wooden version of the Nakaiima Ki-84 Hay-

ate) and the Kugish6 D3Y MyOio (which wasthe wood derivative of the Aichi D3A Vcl).With the loss of heavy industrial machinery, itfell more and more to smaller workshops toproduce components and sub-assemblies foraircraft. Often the labour force was not as

skilled as before and working with wood waseasier as it did not require the sophisticatedtools and jigs necessary for construction ofmore conventional aircraft using metal com-ponents.

Captain Yoshiyuka Mizuyama, an officer inthe IJA's aviation equipment section, was the

man behind the Ta-Go (Ta being short fortake-yari, or bamboo spear). It was his desire

to design and build a plane that was simple inconstruction, used the bare minimum of warcritical materials and could be produced

rapidly. By doing so, the Ta-Go could quicklypopulate the aircraft pool available to unitsdestined for shimbu missions and also

replenish losses in short order. He hopedthat the Ta-Go could be used to defendthe seaside cities of Osaka and Kdbe. In an

effort to help realise the Ta-Go, Mizuyama

approached the Tachikawa Hik6ki K.K. withhis concept. Despite Mizuyama being an IJA

officer, Tachikawa refused to assist him as his

plan had no official sanction and was not

20 Jnpmlrse SEcnrr PRorEcrs: ExpeRturNteL Alncnanr on rHE IJA ano IJN 1939-1945

approved by the Koku Hombu. As such,Tachikawa could not spare the capacity todevelop the aircraft.

Undeterred, Mizuyama discovered a smallshop in the city of Tachikawa within which heand his fellow men went about the task ofdesigning and constructing the first proto-type. Once the concept was completed, workbegan on building the Ta-Go. Using woodlathes to construct the fuselage and othercomponents, the aircraft was made from ply-wood while fabric was used for some of theskinning and coverings for the control sur-faces. The pilot was given a simple acrylicglass canopy. Instrumentation was kept to thebare minimum. The landing gear was fixed.For a motor, a Hitachi Ha- 1 3 Ko 9-cylinder, air-cooled radial engine developing 450hp wasselected, the cowling for it being made fromplain sheet steel. The only armament was a

single 500kg (1,102 lb) bomb. In February1945, the Ta-Go prototype was nearly com-plete when Tachikawa was subjected to a

bombing raid. In the ensuing attack, the shopwas burnt to the ground and the Ta-Go insidedestroyed.

Despite the setback Mizuyama forgedahead, going to Nippon Kokusai Kogyo K.K.(Japan International Air Industries Co. Ltd.) topitch his Ta-Go. In the end the proiect wasaccepted and in part this may have been dueto Kokusai's experience with light aircraftsuch as the Ki-76 (known as S/e114 by theAllies) and the Ki-86 Ko (codenamedCypress), the latter of which Kokusai had builtas the prototype all-wood Ki-86 Otsu. Ofcourse, Kokusai was not as heavily taxed bywartime demands from either the IJA or theIJN and could thus allocate some assets to thedevelopment of the Ta-Go. Despite Kokusaitaking on the Ta-Go project, it still remainedan unofficial design and thus bore no Kinumber.

Mizuyama's design for Kokusai differedfrom the one he proposed to Tachikawabecause the new version was significantlyscaled down and much smaller. In so doing,this reduced the amount of assembliesneeded to produce the aircraft which, byextension, lowered the man-hours requiredto build it. Fewer assemblies meant less useof construction materials. With the resizing,the Ha-I3 radial became too large for the pro-posed airframe and so the Hitachi [Ha-47] 1linline engine, rated at 110hp, was selected as

a replacement. This same engine was used inthe TdkyO Koku Ki-107 all-wood two-seattrainer which was to be the replacement forthe Ki-86 had the former made it into service.

IupERreL JepnruEsE Anl,rv

In addition to the size reduction, steps weretaken to simplify the Ta-Go even more. Gonewas the canopy and the pilot sat in a opencockpit with only a small acrylic glass wind-screen as protection from the elements. Forinstrumentation, only the absolute basicswere used consisting of a speedometer,altimeter, compass and the essential enginerelated gauges such as fuel and oil. The fuse-lage was slab sided and box shaped. Whilethis granted easier construction, it was notthe most aerodynamic design. Much of thefuselage used wood sparring and structurewhile the skinning was of plywood. Thewings were low mounted with squared wingtips and they were hinged just outside of thelanding gear to enable them to fold upwardsto allow the aircraft to be hidden in caves as

well as facilitate their construction within theconfines of caves or small manufacturinglines. Both the vertical stabiliser and the hori-zontal stabilisers were rectangular in shape.

The landing gear was fixed, being made ofsteel tubing and fitted with rubber wheels,each gear supported by a single strut. To pro-vide a modicum of streamlining the tubingthat made up the landing gearwas faired overusing aluminium. The only measure of shockabsorption came from the tlres and the tailskid, the latter also being built from steel tub-ing with a portion rubberised.

The [Ha-47] 1l engine was fitted with anangular plywood cowling, the engine drivinga fixed-pitch, two-bladed wooden propeller.A metal engine mount was used while thefuel tank was situated on top of the engineand used a gravity feed system. Behind thetank and in front of the windscreen was a sim-ple oil cooler, mounted flush in the fuselage.Given the much smaller dimensions of therevised Ta-Go, it was no longer able to carrythe 500kg (1,102 lb) bomb Mizuyama's origi-nal version was designed for. Instead, it couldonly carry a 100kg (220 lb) bomb. The bombwas fitted to the underside of the fuselageand once in place could not be released bythe pilot.

Mizuyama, with the assistance of his onnmen and Kokusai, had completed the firstprototype of the new Ta-Go by the middle ofJune 1945 and it was made ready for flight. On25 June, the Ta-Go took to the air for the firsttime with a Kokusai test pilot at the controls.Not surprisingly, the pilot reported handlingconcerns. After a number of additional testflights, revisions were made to the design.Once complete, Kokusai created a completeset of working blueprints for the productionversion. However, with the cessation of hos-

tilities in August 1945, the Kokusai Ta-Gonever entered production. The close of thewar also saw the end of two Kokusai devel-opments of the Ta-Go, known as the Gi-Goand Tsu-Go. Both remain shrouded in mys-terybecause no information on them has sur-faced to date.

Ironically, Tachikawa would return to theTa-Go when the Gunjushd (Ministry of Muni-tions) authorised development ofMizuyama's initial design following the com-pletion of the Kokusai Ta-Go prototype. Theend of the war would find the TachikawaTa-Go prototype incomplete. As a note, withthe acceptance of the Ta-Go by the KokuHombu, a project number (meaning a Kinumber) was assigned to the Ta-Go - Ki-128.

It has not yet been confirmed whether this Kinumber applied to the Kokusai Ta-Go, theTachikawa Ta-Go or both.

Ta-Go - data

Contemporaries

Messerschmitt P. I 104 Sprengst0fftrager (Cermany)

Specificalions are for the Kohusai Ta-Go,

Special Attack Aircrafl

0ne

Powerplant

One Hitachi IHa-47] I 1, 4-c.vlinder, air-cooled inline engine developing

I I Ohp lor take-off driving a lvooden, lwo.bladed propeller 7.lft in diameter

Type

Crew

Dimensions

Span

Length

Height

Mng area

Wing loading

8.90m 29.211

7.40m 24.311

3.87m 12.711

5.10m' 54.9ft:

34.66k9/m' i,l lbiit'

Weights

Empty

Loaded

345,5k9

585.5kg

761 lb

l,290lb

Performance

)!1ar speed

Cruise speed

Range

Ceiiing

l95kn/h

I Tgkntiit

l50km

4,600m

l2lmph

illmph

93 miles

I 5,091 [r

fumanent

One l00kg (220|b) bomb

Deployment

None. A total ofthree Ta-Go aircralt were constructed: \'lizuyama's own

protot!?e aircraft thatwas destroyed by fire prior to flight, the one built

and flown at Kokusai, and the Tachikawa Ta-Go which remained

incomplete at the end ofthe !var.

21

Interest in airborne forces can be traced as farback as 1917 because they can provide sev-

eral tactical advantages. Being air dropped,parachute troops can be deployed into areasnot easily accessible by ground forces as wellas bypassing defences meant to hinder orrepel attacks from specific avenues ofapproach. Also, the ability to place troopsanyr,vhere on the battlefield requires theenemy to use assets to protect against suchoperations, thereby spreading defendingforces thinner. Such advantages come at acost, however. Airborne forces tlpically donot have the firepower of comparable groundforces nor the ability to remain independentfor long before outside support must beobtained.

Airborne troops were used by all of themajor waning powers in World War 2 andspecial equipment and weapons were cre-ated for use by these units in an attempt toprovide them with heavier firepower. Artillerysuch as the US fumy M1A1 75mm pack how-itzer and the German 7.5cm LG 40 recoillessgun were air-droppable and the troops usedmodified or special small arms such as the US

Maeda Ku-6

M1A1 .30cal carbine and the Japanese Type 2

Paratroop rifle. Despite such weapons, air-borne forces were deficient in one criticalarea: armoured vehicles. The ability to pro-vide airborne troops with armoured supportsuch as tanks was one sought by all the war-ring powers and tank designs did emerge.The key problem was how to send in thetanks with the troops during an operation.One of the first solutions was the glider tank.

The Japanese would create and utilise air-borne forces during World War 2. The IJA

called their forces the Teishin Dan (Raiding

Brigades) while the IJN had the Rikusentai.Both would be used first in 1942 during thefighting in the Dutch East Indies. Unlike theGermans, British and Americans, the Japan-ese did not provide their paratroopers with asignificant amount of specialised healyweapons. ln part, this may have been due tothe fact that the Japanese parachute forceswould rarely be used in their designated role.Instead, much of their fighting would be doneas light infantry (much like the GermanFallschirmjiigers). Nevertheless, the IJA andIJN were considering ways to improve the

striking power of their paratroopers and onesuch plan was a tank borne into battle onwings.

ln 1943, the IJA set the wheels in motion toinvestigate a flying tank. The tumy Head Avi-ation Office in league with the Fourth ArmyResearch Department drafted the initial con-cept for the weapon. The aviation researchsection of Maeda was tasked with producingthe wings that would form the glider portionof the weapon and the Army Head AviationOffice assigned the designation Ku-6 to theglider. The tank was to be designed and builtby Mitsubishi and called the So-Ra (or Sora-

Sha, literally'sky tank'). To ensure there wasno confusion, the Army Head Aviation Officecalled the entire combination the Kuro-Sha(taking the 'Ku' from Ku-6 with 'ro' meaning 6and the 'Sha' for tank).

Mitsubishi's So-Ra was, due to the purposefor which it was intended, a tankette design.With a crew of two (driver/pilot and the com-mander/gunner), the So-Ra was to weigh2,812kg (3.1 tons). The turret was set behindthe driver/pilot compartment and was pro-vided with three large, hinged ports to allow

v U^/ lltu

E

J

Zo

22 JaparuEsE SEcnnr PRoLEcrs: ExprRIr'rrltaL AIRcRnrr op rHE IJA axo IJN 1939-1945

some measure of vision for landing. Armourwas likely very light and was certainly less

than the 6mm-12mm armour protection ofthe Type 95 Ha-Go light tank then being used

by Japanese airborne forces. Three weaponfits were proposed for the So-Ra. The first was

a 37mm cannon (such as the 37mm Type 94

used in the Ha-Go), the second consisted ofamachine gun armament (either a light

weapon like the 7.7mm Type 97 machine gun

or a heavier calibre) and the third was aflamethrower. Power was to come from an

air-cooled engine producing 50hp that was

estimated to give the So-Ra a maximum roadspeed of 42kmlh (26mph).

The glider portion, the Maeda Ku-6, has

been interpreted in at least two ways sincethe original design is not known, the docu-ments either having not survived the war or

have yet to be discovered. One version shows

the wings secured to the So-Ra at the hull, on

either side of the turret, with a tail boom fitted

to the rear of the tank. A horizontal stabilisersat on top of the vertical stabiliser. The dri-ver/pilot moved the control surfaces via wires

that ran into the tank. On the hull front was

the tow cable attachment point. The second

version has the So-Ra fitted with struts on the

hull sides. Atop the struts was the main wingto which twin tail booms were fitted with alow mounted horizontal stabiliser connectingthe vertical stabilisers. ln essence, the So-Ra

would hang below the wing. On landing, the

tank would shed the wings and move into

action with the paratrooPers.

By 1945, the Ku-6 had been completed and

Mitsubishi had produced a full scale mock-upof the So-Ra. Flight testing was conducted for

a brief period and it is likely that the mock-upwas used, suitably weighted to simulate the

2,812kg (3.1 tons) of an operational So-Ra.

The So-Ra was to be towed by a MitsubishiKi-21 bomber. Tests soon showed the diffi-

culty of the concept. The Kuro-Sha sufferedfrom in-flight control problems, the driver/pilot had poor vision and landing was

extremely difficult. Another concern was that

the So-Ra could not stand up to heavier and

more powerful tanks. Any usefulness the

Ku-6 may have possessed was minimisedwith the advent of the Kokusai Ku-7 Man-

azuru (meaning 'Crane') glider that began

development in 1942. First flown in August

1944, the Ku-7 was able to carry a 7,257kg (8

ton) tank within its fuselage which was more

than enough to hold the 6,7l3kg (7.4 tons) ofthe Ha-Go light tank. With the Kuro-Sha's

problems evident, the IJA terminated any fur-

therworkon the Kuro-Shafavouring the Ku-7'

IMpsRrar- hpnNesE AnuY

Maeda Ku-6 - data

Contemporaries

AntonovA-40 (or KT for Kryl'ya Tanka, flying tank) (Russia), Raoul

Hafnels Rotabuggy and Rotatank (UK), Baynes Bat (UK), John Waller

Christie's M1932 (US)

Specifications are based on the second t)atialion of lhe Kuro'Sha,

Lith the So-Ra beneath the uing,

Type Glider (Ku-6)

Powerplant

Dimensions

Span

Length

Height

Wing area

21.97m

14.96m

2.98m

59,99m'

72.lft

4l.gfr

9.8ft

645.83ft'

Weights

Loaded (wjth the So-Ra)

Performance

Mar glide speed 108mph

Tankette (So-Ra)

Trvo

Powerplant

One 4-cylinder, air-cooled, gasoline engine developing 50hp at 2,400rp

4,200kg

l74km/h

Type

Crew

Dinensions

widrh

Length

Height

1.43m

4.05m

1,88m

4.nt

I 3.3f1

6.2fr

Weights

Loaded 2,90Okg

Performance

Nla\ speed 26mph

Armament

One 37mm cannon, machine gun ot flamethrower

Deployment

None. Only one prototlpe built and flown.

23

Manshfl Ki-98

In late i942, the Koku Hombu was looking fora number of new aircraft tlpes as improve-ments on those in seruice. These included a

hear,y fighter capable of conducting ground

attack operations and a high-altitude fighter.Nakajima and Tachikawa were tasked withthe latter, coming up with designs that wouldlater result in the Ki-87 and Ki-94 respectively(see Pages 28 and 53). For the former,

Kawasaki attracted the interest of the Koku

Hombu with their multi-role Ki-i02. However,

Kawasaki's design was not to go uncontestedand the competition would come from a rela-

tively small aviation company.Manshlkoku HikOki Seizo K.K. - the

Manchurian Aeroplane Manufacturing Com-pany Ltd., and better kno'uvn as Manshu, acontraction of the kanji 'Man' in Manshukokuand 'Hi' in Hikdki-was founded in 1938. Man-shr-r was a subsidiary of Nakajima Hikdki K.K.

and produced the Nakajima Ki-27 (code-

named Nate by the Allies) and the NakajimaKi-84 (Frank) for the company. Manshuwould produce few of their own designs

and only one ever saw service, the Ki-79

advanced trainer. Manshu's main plant waslocated in Harbin in the Japanese puppetstate of Mdnzhdugu6. On learning of the KokuHombu's desire for new aircraft, Manshusought to put together a proposal to meet thefighter requirement. The company assignedtheir two best men to the project, engineersNoda and Hayashi, and what resulted was anaircraft that was far from the conventionaltypes Manshl had worked on in the past.

The aircraft was a single-engine fighterwith a pusher, twin-boom configuration. The

heart of the plane was to be a MitsubishiHa-211-lll 18-cylinder, air-cooled radialengine fitted within the fuselage and behindthe cockpit. The four-bladed propeller, situ-ated at the very rear of the fuselage, was dri-ven by a 2m (6.5ft) long extension shaft. Inorder to maintain a well streamlined airframeno air scoops were used; instead, flush inletswere fitted along the top of the fuselagebehind the canopv. To increase the flow ofairto the engine, a fan driven by the engine wasinstalled. Flush outlets forward of the pro-peller completed the air circuit across the

24 JnpenEse Sncnsr PnoLecrs: ExpeRnrnxteL AIRcnapr oF rHE IJA,qNo IJN 1939-1945

engine. The thin wings were mounted lowand on each wing was a boom that ended inan ovoid vertical stabiliser. A single, highmounted horizontal stabiliser connected thetwo tails.

A tricycle landing gear system was used, thenose gear retracting backwards into a wheelwell that ran underneath the cockpit. Each ofthe two main wheels retracted into theirrespective tail booms. As the aircraft sat veryhigh offthe ground, the pilot had to access thecockpit via a hatch in the nose wheel well. Ifthe pilot had to bail out, he had two choices.He could leave in a conventional fashion, buthad to contend with both the twin tails andhorizontal stabiliser along with the propeller.Manshu recommended that the pilot egressthrough the hatch out of the bottom of the air-craft. This method allowed the pilot to avoidbeing dashed on the tail but still had to con-tend with the propeller. Nevertheless, thechances of lowering the nose gear, slidingdown and out through the hatch in a strickenplane were slim and Manshtr were aware ofthis flaw in the design. The canopy was a bub-ble type that afforded an excellent field ofview. Forweapons, two Ho-5 20mm cannonsand one Ho-204 37mm cannon were installedin the nose. Due to the short length of the fuse-lage, the barrels for the cannons, especiallythe Ho-204, protruded out from the nose.

Once the preliminary design for the fighterhad been completed, Manshl submitted it tothe Koku Hombu. Despite the unorthodoxapproach, it was accepted as the Ki-98 andwork was allowed to proceed. Interestingly,the Koku Hombu reiected Tachikawa'sKi-94-l that was similar in concept to theKi-98. With approval in hand, the draft for theKi-98 was finalised by July 1943. Work thencommenced on a wooden mock-up that wascompleted in December. Design work con-tinued into the beginning of 1944 further refin-ing the Ki-98. A scale model of the aircraftwere constructed and sent to Japan for windtunnel testing at Rikugun KokugijutsuKenkyujo. Unfortunately for Manshd, theworsening war situation saw some of theiipersonnel called into service or shifted toother departments and this, coupled with aplethora of design revisions, saw work on theKi-98 slow down. Nevertheless, wind tunneltests showed excellent results and Manshubegan to make the preparations to constructthe first prototlpe.

In the spring of 1944, the Koku Hombuinstructed Rikugun Kokugijutsu Kenkyujo totell Manshu that the Ki-98 should be adaptedto serve as a high-altitude fighter. This they

lupEnral JaparuEse ARuv

did, sending Manshu suggestions for designchanges to the Ki-98 to make it suitable for thenew role. On receiving the news Manshrl hadto substantially alter its initial design to meetthe new demands. With strained manpowerand resources, the mandated changes set theKi-98 program further back and scupperedplans to build the prototlpe.

One of the most important changes was theneed to fit an engine with a turbosuperchargerresulting with the Ha-211-lll being replaced bythe Mitsubishi Ha-211 Ru which incorporatedthis feature. As the turbosupercharger wasexhaust driven it required the appropriateadditional piping, which, of course, was notoriginally included. The new engine wastherefore larger than the original and thismade it necessary for the fuselage to belengthened and slightly widened. As the newpropeller had a larger diameter, the twinbooms had to be moved further apart toaccommodate the blades and, by extension,the wings had to be reworked as well. Finally,the airframe had to be strengthened to supportthe heavier weight. Another alteration was tooffer the pilot a more suitable way to bail outof the aircraft. Given the extreme difficulty inhaving to drop the nose wheel to gain accessto the well hatch, the revised Ki-98 incorpo-rated explosive bolts that shed the tail unit toallow the pilot to exit more conventionally.The weapon fit remained unchanged.

With the new specifications in hand, theKi-98 design was reworked and redrafted butit would not be until October 1944 that theredesign was completed to be followed by amock-up of its revised fuselage. Manshlrexpected to have the first prototype finishedand ready for flight testing by early 1945.

These plans were dashed following a US

bombing raid on Manshu's Harbin factory on7 December 1944. lt was not until January1945 when work commenced on the Ki-98.Despite Manshu attempts to increase thepace of construction work, progress stilllagged.

At the start of August 1945, the fuselage,wings and the tail booms were completedand were ready to be assembled. However,on 8 August 1945, the Soviet Union declaredwar on Japan and initiated its invasion ofMdnzh6ugu6 the next day. With theMdnzhdugu6 Imperial fumy and the Japan-ese Kwantung Army unable to stem the tideofSoviet forces, Manshl ordered all relevantdocumenta.tion including models, mock-ups,jigs, tools and the incomplete Ki-98 to bedestroyed to prevent the aircraft and informa-tion on it being captured by the Soviets.

Manshu Ki-98 - data

Contemporaries

tukhangelskiy BSh (Russia), Saab 2l (Sweden), Vultee V.78 (US),

Bell XP-S2 (US)

Pertornance specificatians arc estimotes based on Manshi's prqections

HighAltitude Fighter

One

Powerplant

One l'litsubishi Ha-21 I Ru l8-cylinder, air-cooled radial engine uith a

turbosupercharger developing 2,200hp [or take.oif, l,960hp at

2.000m/6,56 I ft and I,750hp at 8,500m/27,887[t driring a four-bladed,

metal, 3,6n/l l.8lt diameter propeller

Type

Crew

Dimensions

Span

Length (total)

Boom length

Height

Mng area

Wing loading

Polver loading

ll,24m 36.9f1

11,39m 3i.4ft

8.26m 27.lll

4.29m 14.1ft

23.99m 258.3ft'

187.48k9tm' 38.41b/fl

2,72k{hp 6lb/hp

Weights

Empty

Loaded

3,500kg

4,500kg

7,i16 rb

9,9201b

Performance

Nlar speed

Climb

Range

Endurance

Ceiling

T3lkrni h 454mph

at 10,000m at32,81Oft

5 min 30 sec to 5,000m (16,404ft)

1,249km 776miles

2 houn l5 min at 499kn/h (310mph)

10,000m 32,808ft

Armament

One Ho-204 37mm cannon and two Ho-5 20mm cannons

Deployment

None. The only prototlpe was never compleled and was destrol'ed to

prevent capture.

25

zooEFIoezzc

n

JnpaNEse SscRsr PRoJECTs: Exprntl,lerutnL AtRcnLnr op rHE IJA nNn IJN 1939-1945

Mitsubishi Ki-73 - data

Contemporaries

Consolidated Vultee XP-8 i 'Silver Bullet' (tJS), North American P-5 1 D

'Mustang' (US). Larochkin La-l I (NATO codename fang) (Rusia),

Westland \Itvern (UK)

Specifications

Outside of the intended engine and the aircraft's role, specifications on

the Ki-73 are unknolvn

Deployment

None. The Ki-73 never advanced past the concept stase

Mitsubishi Ki-73

In 1943, the Koku Hombu issued a specifica-tion for a fighter capable of operating for longdistances in order to act as an escort forbomber formations. Despite the defensiveweapons Japanese bombers carried, theywere still vulnerable to interception. If afighter had the extended range, it would beable to protect the bomber formations bybeing able to engage enemy interceptors andallow as many bombers as possible to suliveand deliver their bomb loads. It was thisdesire that fuelled the Koku Hombu to issuetheir specification and from which Mitsubishiwould build the aircraft to meet it.

Mitsubishi's Tomio Kubo, along with engi-neers Kato, Sugiyama and Mizuno, began theinvestigation on how best to meet the specifi-cations. They settled on using a single enginedesign and the heart of it would be the Mit-subishi Ha-20311 engine. This was a 24-cylin-der, horizontal-H, liquid-cooled engine thatwas projected to generate 2,600hp. TheHa-203-ll was chosen due to its horizontal-Hconfiguration - in essence, two flat enginesplaced one on top of the other and gearedtogether (a flat engine is one in which the pis-

tons move horizontally). Each flat engine hadits own crankshaft. Although horizontal-Hengines have a poor power-to-weight ratio,they offer the advantage of being more com-pact, which made the Ha-203-ll the idealchoice for the aircraft, now designated theKi-73.

Unfortunately, Mitsubishi was having a verydifficult time with the Ha-203-ll. In fact,because of the relative complexity of the hor-

izontal-H design the engine experienced nearconstant problems during its development.Ultimately Mitsubishi was unable to over-come these difficulties and abandoned theHa-203-ll. Due to the delays and eventual can-cellation of the engine, Kubo's Ki-73 designwas abandoned even before he and his teamcould produce a mock-up, let alone a proto-tlpe. Even though the Ki-73 went nowhere,Allied intelligence was aware of this new pro-ject. Information obtained from varioussources, including captured documents, ledintelligence officers to conclude that the Ki-73would see selice. As such, in 1944, the Ki-73was assigned the codename Sfeue. As it was,noAllied pilotwould ever encounter the Ki-73in any form.

What Allied pilots might have encounteredhad the war gone on would have been the Mit-subishi Ki-83. Not discouraged by the Ki-73'sdemise, Kubo would go on to design the twin-engine Ki-83 to meet Koku Hombu's specifi-cation. The result was a highly capable aircraftthatwould have provided a challenge toAlliedair power. However, only four Ki-83 proto-types were built before the end of the war.

Very little is known to show what the Ki-73looked like. The artwork depicted for theKi-73 in this book is based on an interpreta-tion of the Ki-73 printed in Richard Bueschel's1966 bookJopanese Code Names. The illus-tration was based on the Ki-83 on theassumption that Tomio Kubo would haveused aspects of the Ki-73 in the Ki-83. Sfeue isshown here in the markings and colours ofthe l0lstSentai.

zI

?E

lnrpsnraL JapeNesE ARI'ry 27

Nakajima Ki-87

cI

==

. .::rrrr.r..i..::.,:l.i::ilai:1@

t**,.{ffi$.;s . ::.,

Altitude is a maior factor in an engine's per-

formance and, by extension, the aircraft as a

whole. Known as density altitude, the higher

the altitude, the less dense the air. The effects

of this manifest themsleves in lower wing lift,

a reduction in propeller efficiency and

reduced horsepower output from the engine.

As such, a plane that was not designed to

operate in such conditions suffers accord-

ingly. The Koku Hombu sought an answer to

the problem and Nakaiima looked to provide

the solution. The result was the Ki-87.

In mid-1942, the Koku Hombu drew uP a

set of specifications for a high-altitude fighter.

These called for a plane capable of operating

at high altitude, heavily armed with a maxi-

mum range of 3,000km (1,864 miles) and

capable of 800km/h (497mph). Examination

of the specifications called into question the

viability of meeting such performance expec-

tations. After deliberation, they were revised.

The role remained the same but the speed

requirement was dropped entirely to the

point that no mention was made at all for a

minimum or marimum speed. The range

requirement was adjusted to one hour of loi-

ter flight time in addition to a half hour ofcombat flight time up to 800kmih (497 miles)from the airfield that the aircraft operatedfrom. Finally, a hear,y armament requirement

called for two 30mm cannons and two 20mm

cannons.With these new specifications, Nakajima

'uvas contracted in November 1942 to produce

three prototypes and seven pre-production

aircraft for the IJA. The proiot)'pes were to be

completed betrveen November 1944 and Jan-

uary 1945 rvith the pre-production planes fin-

ished between February and April 1945. The

design of the Ki-87 rvas headed by Kunihiro

Aoki.Nakajima initially selected the Nakajima

[Ha-44] 1l l8-cylinder radial engine as the

heartof the Ki-87. The IHa-44] 21 (known also

as the Ha-219 Ru) was also considered but

the [Ha-44] 11 would be the engine used in

the first prototype. Both engines were rated at

2,400hp and each used a turbosuperchargerthat would maintain and enhance the

engine's power output at altitude. A turbosu-percharger is an air compressor used to force

air induction to the engine. It does this by

having a turbine and a compressor linked

together via a shared axle. Engine exhaust

spins the turbine which in turn spins the com-pressor which draws in outside air, com-presses it and then directs the air to the intakemanifold of the engine. This compressed air,

delivered at high pressure, results in more air

reaching the cylinders for combustion. The

net effect of this is that at higher altitudeswhere the air is thinner, the turbosuper-charger allows the engine to function as if itwas at a lower altitude where the air is heav-

ier and thus engine performance is not

adversely affected. A benefit of this is that

because the air is thinner at higher altitudes'

there is less drag on the aircraft and since the

turbosupercharger preserues the horsepowerof the engine, overall speed is improved'

A sizable portion of the aircraft's forward

fuselage was taken up by the [Ha-44] 11

engine assembly and the large turbosuper-charger',vas fitted to the starboard side of the

fuselage, just ahead of the cockpit. To cool

the engine, a sixteen-bladed fan was mated

to the four-bladed, constant speed propeller,

turning at 1 50 per cent of the propeller speed.

2g Jap.qxpsE StcREr PRorEcrs: EtpERruENral AtRcRapr ol rnE IJA lr'rp IJN 1939-1945

The engine reduction gear ratio was set at0.578. As the Ki-87 was designed for high alti-tude operation, the pilot was to be providedwith a pressurised cockpit (though the proto-t!?e was not equipped with one).

For weapons, Nakajima kept to the specifi-cations mounting a 20mm Ho-5 cannon ineach wing root, synchronised to fire throughthe propeller, and a 30mm Ho-155 cannon ineach wing to the outside of the main landinggear wheel wells. Ammunition was stored inthe inner wing near the fuselage. Hydraulicpressure was used to load the cannons andthey were fired by electrical triggers. Ifrequired, provision was made to carry a250k9 (551 lb) bomb or a drop tank along thecentreline. Because of the heavy weapon fitand to ensure enough room for the self-seal-ing wing fuel tanks, Nakajima designed alanding gear arrangement that was rare inJapanese aircraft development - the mainlanding gear struts would retract backwardsand the wheels would rotate 90" to fit flushinto the wheel wells.

Given the task the Ki-87 had to perform,Nakajima provided a degree of protection forthe pilot in the form of 66mm thick, bulletproofglass in the front of the canopy and backprotection via armour plate 16mm thick. Toextend the range of the Ki-87, two 300 litre (79

gallon) drop tanks could be fitted under eachwing beside the landing gear wells. The pilotcould jettison them via electrically controlledreleases and these could be used in conjunc-tion with centreline payloads.

As work progressed on the Ki-87, the IJA

saw fit to change the design by insisting thatthe turbosupercharger be placed in the rearof the fuselage beginning with the third pre-production Ki-87. Nakajima protested against

I

z>.

@*

Iupnnrlr. .llplnssn ARuv 29

T}?e

Crerv

Nakajima Ki-87 - data

Contemp0raries SukhoiSu-l(Rusia)

Be.,use the Ki-E7 u)as nat flou)n b its fulllbilit!, Ihe pelomance

\/u/r'tl ' 0rr ('/.lltdl, s ma4e bt \ohtjinu

the change but could do little to sway the IJA

on the matter. In addition, the third prototypeKi-87 would have a reduction gear ratio set at

0.43i and the seventh pre-production Ki-87

was to feature a cooling fan that spun faster to

facilitate enhanced engine cooling.Despite the worsening war situation, Naka-

jima was able to complete the first prototype,

c/n 8701, by February 1945 rolling it out fromtheir Ota Plant. Problems wiih the electricalsystem that operated the landing gear and dif-

ficulties with the turbosupercharger delayed

flight testing. It was not until April 1945 that

the Ki-87 was able to take to the air. Due to the

issues wiih the landing gear, Nakajima for-

bade the test pilot from retracting the maingear lest it fail in the up position, thereby dam-aging or destroying the Ki-87 vuith the resul-

tant belly landing. This, however, preventedany chance of a thorough evaluation of the

Ki-87's top speed and iull manoeuvrability.Consequently, there was no attempt to mon-itor and collect performance data. During the

five flights the prototype did make, the pilot

reported good handling characteristics and iiwas thought that the Ki-87 was superior incomparison to the Nakajima Ki-84 Hayate(Gale).

Even as testing of the Ki-87 was underwaywith work continuing to meet the IJA turbo-supercharger position requirement, Naka-jima designers developed the Ki-87-ll.

Replacing the IHa-44] 11 would be the Naka-jima [Ha-46] 11 (known also as the Ha-219)

that could provide 3,000hp. The turbosuper-charger was situated in the belly of the fuse-

lage as demanded by the IJA. Performanceestimates showed a 4 per cent increase inspeed compared to the Ki-87.

Ultimately, the Ki-87's design team failed toovercome the problems with its engine.

Because they were unable to solve difficultieswith both the turbosupercharger and the

IHa-44] 1 1 aswell as the temperamental land-

ing gear system, the Ki-87 would make nomore test flights. When hostilities ceased the

other two prototypes remained incompleteand the Ki-87-ll rvas still on the drawing board.

Hish-Altitude Interceptor

0ne

Poserplant One trakajima lHa.lll I l, l8'olindeL. ail'cooled

rad ial developing 2,100hp lor take-ofl 2.20|)hp at l ,r00m' l -020ft, 2.050hp

at 6.000m1 I 9.685|t and 1 ,8i0hp at 1 0.i00m ,i1, l50il and diiYing a constant

speed, l.bladed propellei

Dimensions

Span

Length

Height

\\iing area

\\iing loading

Po*'er loading

l3.llm

I L79nr

1.18m

2i.99m'

2l6.29ksrm

2.35kq'hp

.t l.l.)fr

38.7ir

ll.itr2i9.8ft,

11.3 lbrfr

5.2 lbrhp

Il'eights

Empt\

Loaded

\larimrtm

l,387kg

i.632kg

6.100k11

9,62Ib

I 2.116 lb

13,1J8tb

Perfornrance

\lar specd

Endurance

Climb

Ceilinq

i0Tkmrh

at I l,i]il()nt

2 hoLrs

1l min l2 sec to 10,000rn (32.8J0it)

l2,85rn 12,liii1

l39mph

al ll6.090li

=

=>.

E{LEZfumament

Tu o 3()nm Ho-i ii cannons, Tu o 20mm Ho.5 cannons and ptorision ior

one i5l lb bomb

Deplolment

fone.0nlvone Ki-87t\as completed and test fl01\nuith h\0 Othels

incomplete beiore the trarended.

Sunivors

\akarinra Ki-8i (FE-1iii)

This n as the onh Ki-87 to flr. havinq the sctial 8i0 l. CaptuLtd at the I.lA aiL

base at Chofu, the Ki-87 (nicknaned 'Big Bot br the nlen \\ h0 sas the

larqe aircraft) nas crated and shipped to the ll5, appearinq on l0 \latch

l916 at \lA\lA. Under iestoration fot the museurn. lhe Ki'8i sas s00n

rnovcd lo Park Ridqe. Hotret er. ailer I \lav l9J9 (lhe last nriiten report

docunleniing the airciaft) all trace oithe Ki"87 disappcared, a likehvlctim

oithe cutters torch.

Nakajima Ki-87 (FE.l55)

It has been surmised that FE-15; \\as, in fact, altpogiaphical enot nlade

0n a Iater rep0il concerning Ft-157 ftec belo$j, On thc flip side, it mai

be that the FE-155 enhr \\as a cOrrection and that FE-l;7 as listed on the

earlierLeport nas designated in enor. In either case,Onlr hl0 ofthe Ki'8i

aircraft reached the L'S.

Nakajinra Ki-8i (FE-lri)

FE-157 u,as, most likeh, the sccond 0lthe two remaining Ki'87 protottpes

found incomplete u'hcn the trai endtd. Listed as FE'l 57 on l0 trlarch

1916 at \1A[1A. lhc plane uould lati'r reappear 0n a ] August l916 report

as FE.155 and uas located at lhe A0A\1C in Netraik. \en Jetsev.

\o lurthcr trace of this Ki-s7 e)iists aiter the AuqLrst report and the aircraft

nas most piobablr sctapped.

30 I.rparuesr SEcirEr Pno.lEcrs: EtpEnlntElltel AtRcnanr oF THE IJA AND IJN 1939-1945

By 1945, Japan was reeling from one defeatafter another in the face of the Allied advance.With the possibility of an Allied invasionlooming in the minds of Japanese militaryleaders and planners, several means to repelthe invaders were considered, investigated,and in some cases, allowed to proceedtowards a finalisation. One of the ideas devel-oped was to use aircraft for shimbu (suicide)missions against the invasion fleet. Airworthyaircraft of any type were to be thrown againstAllied shipping. In order for the missions tosucceed, wave attacks were envisioned,involving scores of aircraft. Sheer numberswould ensure successful hits on naval shipsand landing craft even in the face of hearyanti-aircraft fire and c.ombat air patrols. Evenone aircraft that struck a ship had the poten-tial to cause significant damage. Such massattacks, however, led to the conclusion thatthe available pool of aircraft would quickly bedepleted. Thus, it was clear that an airplanehad to be designed that could be built rapidlyto swell the number of aircraft available forthese shimptr missions. It was Nakajima thatwould provide one answer.

On 20 January 1945, the IJA issued specifi-cations for an aircraft that could be built bysemi-skilled labour, would use very few warcritical materials, had the ability to accept anyradial engine with a 800hp to l,300hp rating,was easy to maintain in the field, was able tocarryat least one bomb and had a maximumspeed of at least 340kmih (2llmph) withlanding gear and 51skm/h (320mph) withoutlanding gear. Nakajima was tasked with mak-ing the specifications a reality and engineerAori Kunihiro was assigned the project. Kuni-hiro would have assistance from the MitakaKenkyujo (Mitaka Research Institute) and OtaSeisakusho K.K. (Ota Manufacturing Co Ltd).

Because semi-skilled workers would beused to build Kunihiro's aircraft, the Ki- 1 I 5 Kowas simplicity itself. The fuselage used a steel

In'lpEntel JapaxEss ARlrv

Nakajima Ki-l 15 Tsurugi

structure with steel panelling and centre sec-tions with tin used for the engine cowling.The tail was made of wood with fabric cover-ing while the slightly swept wings were ofmetal with stressed skinning on the outerwing surfaces. The Ki-I15 Ko could accept avariety of radial engines and to simplify theinstallation only four bolts were used tosecure the engine to the fuselage. The Naka-jima [Ha-35] 23 (Ha-25) radial engine wasused on the prototype Ki-l15 Ko and wouldbe found on the subsequent production air-craft. The pilot was provided with an opencockpit with simple instruments and con-trols. A crude aiming sight was provided as

well. The landing gear could be jettisoned

after take-off, had no suspension outside ofthe balloon tyres and was made out of pipes.For weapons, the Ki- 1 1 5 Ko carried only a sin-gle bomb and this was held in a recess underthe fuselage between the wings. The heaviestbomb that could be carried weighed 800kg(1,764Ib) and the bomb had no provision forrelease from the cockpit.

In March 1945, the prototype of the Ki-l 15

Ko, called the Tsurugi (which means'sword'or 'sabre'), was rolled out and flight testingcommenced. As soon as the trials had startedproblems began to surface. The landing gear

contributed to poor ground handling and thiswas compounded by the poor view affordedthe pilot. Once in the air, the flight character-istics of the Ki- 1 1 5 Ko were anything but stel-lar and even skilled test pilots had somedifficulty in flying the aircraft, let alone a pilotwith minimal training. Nevertheless, given

the mission of the Ki-1 15, flight trials contin-ued while modifications were investigated toimprove the aircraft. By June 1945, the initialflight testing was completed. Two furtherchanges were made to the Ki-l l5 Ko and thisinvolved adding suspension to the landinggear and including auxiliary flaps to theinboard trailing edge of the wings. Production

models of the Ki-l15 were to be fitted withtwo solid-fuel rockets, one under each wing.The purpose of the rockets was to boost thespeed of the airclaft during the final, terminaldive on the target. With the Ki-l 15 Ko deemedacceptable, Nakajima began production ofthe Tsurugi at both their lwate and Ota plants.The IJA anticipated that 8,000 aircraft permonth would be assembled from productionlines scattered throughout Japan.

Even with production underway, stepswere being taken to further simplify theKi-115. To save on precious metals, the wingsof the Ki-115 Ko would be replaced withwooden versions and the wing areaincreased. To better address pilot vision, thecockpit would be moved forwards. The ver-sion of the Tsurugi was to be designated theKi-l15 Otsu. A variation of the Ki-l15 Ko wasthe Ki-115-lll (also known as the Ki-l15 Hei).The only two modifications was the provisionof a bomb release and cockpit being movedeven further forwards. But even these modelswould not be the end because the Ki-230, afurther development of the Ki-l 15, was alsoinvestigated.

The IJN, having learned of the new plane,

became interested in the Ki-l 15 and sought toproduce it for themselves. To facilitate this,Nakajima provided Showa Hikdki K.K.(Showa Aeroplane Co Ltd) with two Ki-115

Ko aircraft. In IJN service, the aircraft was tobe called the Toka, meaning Wisteria. Showawas to adapt the design to accept any num-ber of IJN radial engines from older, refur-bished motors to ones then in current seruice.

By the time ihe war ended, Nakajima hadonly been able to produce 104 of the Ki-l15Ko (22 from the Iwate plant and 82 from theOta plant) and none would be used in anger.Neither the Ki-115 Otsu, Ki-115-lll or theKi-230 would be constructed, remaining for-ever as design board projects. Likel,r,ise,

Showa had no time to produce the Toka.

z

31

Japa:resE Slcrrrt Pno:Ecls: Etprnlttlt"rt,tl Arncnalr on rHe IJA lln IJN 1939-1945

z2F

oE

treE

ocFE

Nakajima Ki-l 15 Tsurugi - data

T}?e

Crew

Contemporaries

Bell XP-77 (US), Blohm und Voss BV40 (German.-v), Zeppelin 'Fliegende

Panzerfaust' (Germanrl, \'lessenchmitt N'le328 (Germanv).

['leserschmitt P 1104 (Germany)

Spe' ilkutioni in purpnthc:es ate lor lhe Ki-l l5 lt:u Ki-t ljlll and aty

estimates onlj. The Toha uauld harc had simi[at dimensions though the

ueights and speeduould hate uaried dependingonthe engine used.

Survivors

Nakajima Ki-i 15 Ko Tsurugi (FE-156)

One offour caplured at Nakajima's No.l plant in Ota. Gunma Prelecture,

this Ki-l i 5 Ko Gerial I 002) uas listed on the ['1Al{A I August 1946 report

as being in storage and was moved to Park Ridge in September 1919.

Luckl'enough to sunive the scrap heap, the Ki-1 15 Ko is cunentl.-v in

storage, unrestored and in poor condition at the Paul. E. Garber iacility

in Suitland-Silver Hill, i\4anland (pictured lelt).

Nakajima Ki-ll5 Ko

Apparentlv another surviving Ki-l 15 Ko is beinq restored in Japan but

there are felv, ifan,v details. on luho is restoring the aircraft nor the

history of the Ki-1 I5 involved.

in 1991, tlo other Ki'l l5 aircraft irere reporled to be found in.lapan,

one in Kanda and the other in Koganei. \\ho has them and in u'hat

condition is neither knoun nor conllrmed.

Nakajima Ki-230 - data (estimated)

Special AitackAucrall

0ne

Powerplant One Nakajima IHa-351 23, 14-cllinder, air-cooled

radial engine developing 1,1 30hp for lake-off and 980hp al 6,000nr/

l9.o85ll (.ame engine rrar to be u.ed in rhe Ki-l l;0r.u Ki-l l5-l1l

Dimensions

Span

Length

Height

\Ving area

lVing loading

Polver Ioading

(0tsuilll)

(0tsu/lll)

(Otsu/lll)

(0bu/ilr)

(0tsu/lll)

(0tsuilll)

8.59m

9.69m

8.53m

8,53m

3.29m

3.29m

12.39m'

11.49m'

207.99kgim'

181.13k9/m'

2.3lkghp

2.3lko'hp

28.2ft

31.8ft

28.0ft

28.0ft

t0.8ft

10.8ft

133.4ft.

156.0f1

42.6lbrft'

37.1 lbrfl'

5.1 lbihp

5.1 lbihp

T}?e

Crew

Suic;de Attack Aircraft

One

Powerplant

One l4-cvlinder, air-cooled radial engine developing at Ieast 1.100hp.

Weights

Emptv

Loaded

l'larimum

Dimensions

Span

Lenglh

Height

\\ring area

39,69m

8.47m

3.29m

13.09m'

1.8ft

'27.811

10.8ft

I 4 t.Ofr

3,61 5 lb

3,2;lb

s,6881b

;,7981b

6,319 1b

1,640k9

(Otsuilll) l,69{)kg

2,580k9

(0lsurlll) 2,630kg

2,880k9

Weights

Empt!

Loaded

l,700kg

2,400kg

3,747tb

5,291 lb

Performance

trlal speed

Cruise speed

Range

Ceiling

5;lknlh

at 2,800m

620knih

(0tsurlll) at5,800m

300kni/h

l,l99km

(Otsu/lll) l,l99km

6,500m

(Otsu/lll) 6,500m

312mph

at 9,i86it

385mph

at 19,028it

186mph

715 miles

745 miles

21,32511

21,32;ft

Performance

\'lai speed

Range

Ceiling

557knl'h

at 2.800m

I.l99km

6.500m

346mph

at 9,185ft

745 miles

21.325fr

Armam€nt One 250kg (55 I lb), 500kg ( I, I 02 lb) or 800kg

(1,i64 lb) bomb Game ior the Ki-l I 5 Otsu/Ki-l l;-llD

Armament

One 250kg (5i1 lb) or 500kg (l.l 02 lb) bomb

Deplolment

None, A total oi 105 Ki-1 I5 Ko aircralt rvere built but none saw combat

No Ki-l l5 Otsu. Ki-i l5lll, Ki-230 or Toka aircrafl $erc construcled.

t&,

lupERrnr- .lapallesE ARl,lv JJ

Nakajima Ki-201 Karyu

ip?!G

The Ki-201 depicted here sports the colours of the

244th Sentai, one of the more successful Japanese

home defence air units.

As a result of the development of the Naka-jima Kitsuka for the IJN, Japan's first turbojet-powered aircraft to fly (see Page 114),

Nakajima rvas in the position of being the

leader in the fledgling iet aircraft field. Seek-

ing to expand on that position, Nakajima tookit upon themselves to offer a jet that rvould be

superior to the Kitsuka. This rvas to make the

most of rvhat little data was received fromGermany on the N'lesserschmitt N4e 262. Withthe Kitsuka under development for the IJN'

Nakajimaprovided the IJAwith their proposal

for rvhat was to be ihe definitive Japanese

version of the Me262, the Ki-201 Karyu, the

Fire Dragon.Depending on the source, the IJA was or

was not interested in developing its own jet

aircraft. However, evidence supports the fact

that the IJA wished to have its own jet-pow-

ered fighter or was looking to have an optionshould the Ki-202 and fighter variant of the

Kiisuka not meet their expectations. In Octo-

ber 1944, ihe Japanese embassy informed the

Germans that the IJA would be the producer

of the Me 262 and requested reports and pro-jections for the production of 100 and 500 air-

craft a month. It was known that the wartimemanufacturing capability of Japan could notproduce an exact copy of the Me262 and

adaptations '"vould have to be made toaccommodate .lapanese capabilities. Naka-jima sought to provide that answer.

The genesis of the Ki-201 took place on 12

January 1945 rvith the formation of the design

team led by Nakaiima engineer Iwao

Shibuya. Unlike the Kitsuka proiect, from the

outset Shibuya designed the Karyu as a

fighter. ln addition, Shibuya realised that the

aerodynamics of the Me 262had been tested

and felt assured that by applying as much of

the design of the N4e 262 into the Karytt as r,vas

possible rvould result in an aircraft that wouldneed minimal testing before production was

staited. This idea was shown to good effectin the development of the Mitsubishi J8M

Syusui.

Shibuya had the same access to the Me 262

information as the IJN. It consisted of sketches

34 JApANESE SrcnEr Puo:Ecrs: ExpEnr:uenrll AIncRnnr or rna IJA AND IJN 1939-1945

.der',t-,-

IlrprnrnI- JnpnNEse ARlrv 35

Fighter

One

Type

Crew

Nakajima Ki-201 Karyu- data

Contemp0raries Messerschmitt \1e 262A'la (Germany), Avia S'92

Turbina (Czechoslovakia)

Powerplant

Trvo Ne 230 arial-florv turbojets rated at 885kg (1,951 lb) of static thrusl

each; later, t1v0 Ne 130 arial-florv turbojets rated at 908kg (2,002 lb) of

static thrust each

and drawings of the Me 262A-1 and little else'

Whereas the Kitsuka only bore a superficialresemblance to the Me262, Shibuya's design

would seek to match the Me 262 as much as

possible. Shibuya and his team may have had

little, if any, contact with the Kitsuka develop-

ers despite being in the same company. The

first draft of the Karyu nearly matched the

dimensions of the Me 262. However, it fea-

tured a straight wing as opposed to the swept

wing of the German jet. This was quickly

changed and the revised Karyuwas largerand

heavier than the Me262, but replaced the

straight wing with a gently swept wing'Initial design work, including wind tunnel

testing, was completed in June 1945' For all

intents and purposes, the Ki-201 was a larger

derivative of the Me 262. That it was bigger

and heavier than the German jet may point toadaptations the Japanese had to make in

order to produce the Karyrr. For example, the

Japanese did not have the experienced fabri-

cators to make the thin, sheet steel used in

the nose of the Me 262. The result was that the

Karyr-r's nose had to make do with duralumin

',vhich was heavier. In addition, it is certainthat the Karyr1 incorporated simplifications to

accommodate production by semi-skilledlabour and construction using less criticalwar materials. The latter was borne out by the

intense interest by the Japanese in obtainingthe German process for making plywood(and likely the bonding glues as well) whichthe Germans used in their aviation industry

because, although Japan was lacking in avia-

tion metals by the close of the war, they had

ample access to wood.The Karlu was initially slated to be fitted

with Ne 230 a-rial-flow turbojet engines each

rated at 85kg (1,951 lb) thrust. These were cal-

culated to push the Kary-r at a maximumspeed of 812km/h (504mph). However, itwasalso planned that once they became avail-

able, the Ne 230 engines would be switchedfor the improved Ne 130 axial-flow turboiets.

Projected to produce 908kg (2,001 Ib) of

thrust each, the calculated speed of the Karyu

with the Ne 130s was a maximum 852km/h(529mph).

For armament, the Karyu was fitted withtwo Ho-l55-ll 30mm cannons and two Ho-5

20mm cannons. On the chance that the IJN

might acquire the Ki-201, provision was also

made to use two Type 5 30mm cannons and

two Type 99 20mm cannons. More notablewas that the Karyrlwas slated to be equippedwith the Ta-Ki 15 airborne intercept radar.

Used in coniunction with the Ta-Chi 13

ground control radar, the Karyl could be

guided to its targets by ground controllerswith a 153km (95 mile) radius. Such a system

would have been a benefit in lowJight, night

or poor flying weather interceptions. In addi-

tion to the cannon fits, the Karyu was to be

capable of carrying a 800kg (1,7631b) or

500kg (1,102Ib) bomb.With the initial progress of the IJN's J8M

Syusui program, which would provide the IJA

with the Ki-200 and the subsequent IJA Ki-202

Syusui-kai project, IJA interest in the Ki-201

looked to have waned. The result was delays

in further developing the Karyu. Nakajimawanted to have the final design of the Ki-201

completed by July 1945 with more advanced

testing underway by August. The first proto-

type of the Karyu was to be completed and

ready for flight trails by December 1945, and in

addition, a further 18 examples of the Ki-201

were to be built and delivered by March 1946.

Despite the delays, work commenced on

the prototl,pe. Nakajima's Mitaka plant,

which was located on the western edge ofToky6, was the facility for the prototlpeKi-201's construction. Regular production ofthe Ki-201 was intended to be carried out at

the Kurosawaiiri Research Works No.2l situ-

ated near Kitakami, in Iwate Prefecture, in

Honshu. The fuselage for ihe Karyu was

nearly complete when Japan surrendered on

15 August 1945. With the surrender, work on

the Ki-201 ceased. Itwould be nearly 30years

before the next Japanese designed and built

iet fighter would fly, this being the MitsubishiF-1 which first flew on 3 June 1975.

Dimensions

Span

Length

Heighl

Winq area

13.68m

I L49m

4.05m

23.96m

44.9fr

37.7fr

13.3ft

258|t:

Weights

Empt]

Loaded

Overload

4,495k9

7,021kg

8,492k9

9,9l0tb

15,478 lb

18,722Ib

Performance

I'lax speed

(Ne 230)

(Ne 130)

Landing speed

Mar dive speed

Take-off distance

Range at 60110 thrust

Fuel capacitv

Climb (Ne 230)

(xe 130)

(Ne230)

(Ne 130)

Ceiling

812kmih 504mph

at 10,000m at 32,808ft

845km/h 525mph

at 10,000m a|32,8081t

l6lkm/h lOOmph

1,006kn1,h 625mph

945m

1,588m

987km

3,l00it loaded

5.209ft in overload

613 miles

at 7,995m at 26,2301t

2.200 to 2,590 litres 560 to 684 sallons

6 min 54 sec to 6,000m (19,685it)

6 min l7 sec to 6,000m (19,685ft)

l4 min 56 sec to 10,000m (32,808f1)

l3 min l5 sec ro 10,000m (32,808ft)

12,000m 39,370ft

Amament

Tlro Ho-l55ll 30mm cannons and tivo Ho-5 2Omm cannonsi one

1,763 lb bomb or one I,I02 lb bomb; proposed \a\ version to be fi tted

rvith hlo Tlpe 5 30mm cannons and hvo Tlpe 99 20mm cannons

Deployment

NOne. The protot\pe Ki-201 rvas incomplete by the close of the war'

36 J.qpeNEse Secnsr Pnorscrs: ExpenrN,rlNral AIRcnapt oF rHE IJA AND IJN 1939-1945

Rikugun Ki-93

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At the time the Ki-93 was conceived the warsituation for Japan was dire. The mainlandwas suffering from near daily B-29 raids andlooming on the horizon was the anticipatedUS invasion of Japan. A means to counter theB-29s as well as to attackAllied invasion shipswas needed. The resulting Ki-93 would be afirst and a last for Rikugun and Japan.

When Rikugun Kokugijutsu Kenkyujobegan the design research for the Ki-93, thegoal was to provide an aircraft that could pro-vide a platform for anti-bomber operationsand anti-shipping missions. In both cases theaircraft had to be able to absorb damagewhen flying in the face of interceptors, thedefensive machine guns of the bombers, andthe anti-aircraft weapons of ships.

Two versions of the all-metal Ki-93 were tobe constructed. The first, the Ki-93-l Ko, wasthe heary fighter that would combatbombers. The second was the Ki-93-l Otsuand this was the anti-shipping model. TheMitsubishi Ha-211 radial engine was consid-

ered at first to power the Ki-93 but both mod-els were ultimately powered by two Mit-subishi Ha-214 18-cylinder, air-cooled radialengines, each providing a maximum of2,400hp. In order to give the aircraft a mea-sure of survivability in the face of enemy fire,armour plating was used. The pilot was pro-vided with five armour plates, each 12mmthick. Two plates were placed just forward ofthe cockpit in the nose, one on each side ofthe pilot and the fifth would protect his back.The front glazing was composed of 70mmthick bullet proof glass. The rear gunner wasalso protected by a 12mm armour plate, offer-ing defence from rounds being fired at theKi-93 from behind. Likewise, the fuselage fueltanks were given a measure of protectionfrom incoming fire via an 8mm thick armourplate. Each engine was also provided witharmour plating in the nacelles. Should thearmour protecting the fuel tanks be pene-trated, each tank was self-sealing and, toprevent fuel fires, had an automatic fire

IupERtar- JapaNesE AnN,ry JI

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38 .lapar-EsE SrcnEr Pno.lncrs: Ext'ERIntEllal AtncRnn oF rHE IJA ,qNn IJN 1939-1945

Tlpe

Rikugun Ki-93 - data

Contemporaries

Henschel Hs I29B-3.,\\ a (GemanlJ, \'lessenchmitt ['le 110A-]rLl{

(Cermanr'). Tupoler, ANT-46 (Russia), North American B.25G Mitchell

(tS), Bell YFlll Airacuda (LrS), Curtiss XP-71 (ltS). de Havilland

\'losquilo FB ['lk.X\rlll (tJK)

Heal'Fighter (Ki.93l Ko) and

Ground Atlack Aircraft [Ki-93-l Ohu)

Tuo

Po$'€rplant

Tu,o tr{itsubishi Ha-214, l8-olinder, air.cooled radials, dereloping

2.100hp for take-ofi, l.9i0hp at 1,500mi 1,92011 and 1,73l.)hp at

8.1i2mi27,72-qit: each engine drole a ti-bladed. metal propeller

extinguishing system. Finally, a defensivearmament, consisting of a single 72.7mmHo-103 machine gun was fitted in a rear firingposition to be operated by the second crew-man.

The differencc in the two versions rvas inthe offensive weapon fits, both mounted inventral gondolas. The Ki-93-l Ko wasequipped with a powerful 57mm Ho-401 can-non and this was backed up by two 20mmHo-5 cannons (although one initial design didaway with the two Ho-5 cannons and used asingle 37mm cannon with 40 rounds ofammunition). It was anticipated that theHo-401 cannon would inflict enough damagewith a single hit to cripple or shoot down aB-29. The Ho-401 could fire 90 rounds perminute with a muzzle velocity of 518.2mlsec(1,700f1/sec). For the Ki-93-t Otsu, the large75mm Type 88 cannon was fitted. Theweapon was an adaptation of the Type 88

anti-aircraft gun that had been modified foruse on aircraft. Besides the Ki-93, thisweapon rvas also used operationally in the

Mitsubishi Ki-109 (flown by the 107th Sentai).The Type 88 had to be hand loaded by thesecond crewman. In addition to the cannonthe Ki-93-l Otsu would carry two 250k9(551Ib) bombs.

Rikugun had Dai-lchi Rihugun Kokusho,located in Tachikawa (r'vhich is about 24

miles from the centre of Tdkyd), construct theKi-93. The first prototype in the Ki-93-l Ko con-figurationwas completed byApril 1945. In thesame month the aircraft successfully took tothc air making it the first Rikugun aircraft to bebuilt and flown. However, further flight testingwas hampered by the war situation, so muchso that the test program was never com-pleted. Despite the lvorsening conditions inJapan and delays with the flights of the firstprototype the second aircraft in the Ki-93-lOtsu configuration was completed. However,it'"vould never fly.

With the surrender of Japan, the Ki-93

would become the last hear,y fighter andground attack aircraft to be built during thewar.

Dimensions

Span

Length

Height

\\ring area

Wing loading

Pouer loading

18.98m

l4.20nr

1.81m

5.1.74nr

18.l.80kgim

2,22kq,'hp

62.3iI

{6.6fl

15.9ft

589.3ft,

39.9 lbiir

4.9lbrhp

lVeights

Emptv

Loaded

7,686k9

10,660kg

16,94;lb

23,501 lb

Performance

l\'1a:i speed

Cruise speed

Range

Endurance

Clirnb

Ceiling

otc

;625kmrh

at 8,300nr

350kmih

3.000km

6 houn

4 min l8 sec to 3.000m (9,810f1)

9 min 3 sec to 6,1)00m (l9,fi8Sfl)

I 2.049m 39.;30tt

fumament

One 57mm Ho-101 cannon with 20 rounds 0f ammunition, hro 20mm

Ho-5 cannons n ith 300 rounds ol ammunilion per gun and one 1 2. Tmnr

Ho-1 03 machine gun iljth 400 rounds of ammunition (Ki-93.1 Ko); One

75mm lipe 88 cannon, one l2,imn Ho-103 machine gun and tuo

250kg (551 1b.) bombs (Ki-931 Otsu)

Deplolment

\one. Tuo Ki-93 prototipes (one of each lersion) rrere produced but

did not enler producti0n belore the end 0f lhe \rar.

Survivors

Rikugun Ki-93.1 Otsu (FE-152)

The second protollpe that had not flou'n bv the end oi thc narrvas

taken at uhat is present dal Takahagi in lbaraki Prelecture. The aircrail

was craled and arriled at I'lA['lA being listed on ]0 \'{arch 19{6. It was tcr

be restored for displav and this began on September 1!116. Moied to

Park RiJge on ld 5eplember lu 10. All lrar * ut lh" Lirr:i-l 0l'u .topped

at Park Ridge in 1949.

388nrph

at 27.230ft

2liniph

1.861 miles

x+-G €E

IupEnrnl Japa\sse AR\,rv 39

Rikugun K-202 Syusui- Kai

JapaNEsr SEcnEr PRotscrs: ExpEntnEIltnL AtRcnapr on rHs IJA eNo IJN 1 939-l 945

The IJA was not satisfied with the Ki-200 (the

IJA designation for the Mitsubishi J8M1 Syusui

- See Page 96). They felt that the IJN's plans toadopt and adapt the Messerschmitt Me l638as the J8Ml would amount to the same, if notmore, effort and development compared tocreating a new design based on, but not a

direct adaptation of, the Me 1638. Although theIJA attempted to make the IJN see their point-of-view, the IJN pushed aside such plans, forg-ing ahead with their J8M program. Thus, theIJA took it upon themselves to design the bet-ter aircraft they had wanted from the outset.

The IJA saw a main flaw in the Ki-200 thatresulted in aspects of the plane's performancethat they found unacceptable: the limited fuelcapacity. Because of this, combat endurancewas reduced and fuel was rapidly consumedby the KRl0 (Toku-Ro 2) engine. Even with theIJN's proposed J8M2, which removed a Tlpe 5

30mm cannon to make way for more fuel, theIJA felt that the endurance was still insufficient.Starting in 1945, Rikugun Kokugijitsu Kenkyujobegan the process of developing the IJA's ownrocket aircraft using the Me 1638 as a template.This development was in secret and the desig-nation given to the aircraft was the Ki-202Syusui-Kai which meant 'Autumn Water -Improved'.

The IJA took the obvious route andincreased the fuel capacity by stretching thefuselage to make room for larger fuel tanks.They also planned to use an improved motor,but exactly what power plant depends onwhich source is referred to. Two main optionsappear. One was the KR10 as used in theKi-200 that developed 1,500kg (3,3061b) ofthrust, but with a secondary rocket added pro-viding a further 400kg (881 lb) of thrust. Theother motor was the KR20, which may also beknown as the Mitsubishi Toku-Ro.3. The KR20promised 2,000kg (4,409 lb) of total thrust andmay have been fitted with a cruise chamber.This is a secondary combustion chamberwhich was typically mounted above or belowthe main combustion chamber. The purposeof having two such chambers is that the mainone (or both if necessary) can be used for fullpower needs such as take-off and rapidascent, while the cruise chamber has a lowerthrust output and can be employed for normalcruise speeds once the plane is aloft and themain chamber shut off. The benefit of this isthe conservation of fuel, allowing the plane toremain airborne and in action longer.Wartime Allied intelligence reports stated thatthe Germans had provided data to the Japan-ese on the Walther HWK 509C rocket motorwhich used a cruise chamber. lf this was so,

Il,tpERrnr- Japaruesr Anuv

then the KR20 was most likely the Japanesedevelopment of the HWK 509C motor and theanswer the IJA was looking for in extendingthe range of the Ki-202. Contemporary illustra-tions of the Ki-202 clearly show some form ofa secondary means of thrust. As a stop-gapmeasure, the Ki-202 could have accepted theKR10 motor if problems arose with the devel-opment and production of the KR20 and thus

any delays in flight testing could have beenavoided.

Although the Ki-202 was larger than theKi-200, no attempt was made to include alanding gear system. Like the Ki-200, theKi-202 retained a central landing skid, tailwheel and would use the iettisonablewheeled dolly for take-off and ground han-dling. No provision for catapult launching is

known to have been considered as a means toconserve fuel that would have been con-sumed during normal take-off procedures.

For weapons, the Ki-202 was slated to usetwo Ho-155 30mm cannons, one mounted inthe each wing root, the same as the Ki-200.

Insofar as the larger size and motor, theKi-202 was estimated to have an endurance of10 minutes and 28 seconds, whereby theKi-202 was calculated to achieve 5 minutesand 30 seconds. With a near doubling of theendurance time, this would have allowed theKi-202 to remain in combat for a longer periodor, at the least, extend its operational radius. Itwas projected that the final design of theKi-202 would be completed by February 1945

with construction of the first prototype com-mencing shortly afterwards. The first test flightwas scheduled forAugust 1945.

As it was, the Ki-202 design would remainjust that, a design. When the war ended, nometal had been cut on the Ki202 prototy?enor was a mock-up even constructed. In part,the Ki-202 program may have hinged on thesuccess or failure of the J8Ml. The technicalissues in producing the KRl0 in a reliable formmost likely stymied work on the KR20, whichwas to be the main powerplant for the Ki-202.The problems with the KR10 delayed flighttesting of the J8M1 until July 1945 and eventhen, a fuel system failure caused the crash ofthe Syusui during its maiden flight. This set

back the J8M1 further still and although thefuel system problem was corrected, the warended before any further flights could bemade. Had the J8M1 succeeded and the IJA

version, the Ki-200, entered service, it is likelydevelopment of the Ki-202 would have rapidlyproceeded and had it succeeded, the IJA

would have offered it to the IJN. If accepted,the designation would have been the J8M3.

Rikugun Ki-202 Syusui-Kai - data

Contemporaries

Messerschmitti\'le l63C-1a (Cermanr)

Type

Crew

Interceptori Fighter

0ne

Powerplant (planned)

0ne Toku-R0.3 (KR20) bi-iuel rocket motor producing 2,000kg (4,4091b)

0f thrust $ith supplemenlary r0cket 0r cruise chamber producing 100kg

(880Ib) olthrust

Dimensions

Span

Length

Heighl

Wing area

Wing loading

9,72m 31,9ft

7.68m 25.2f1

2.74m gft

18.39m: l98ll:

272.43k9i11' 55.8ib/ft'

Weights

Empty

Loaded

Nlaximum loaded

l,6lgkg

3.384k9

5.01 5kg

3.5691b

7,4601b

I l,057lb

Performance (estimated by Rikugun)

Mal speed

Landing speed

Range

Climb

900kmih 559mph

at 10,000m at32.808i1

l32krD-h 82mph

i0 min 28 sec ofendurance

I min 21 sec to 2.000m (6.561|t)

2 min 0 sec to 4,000m (l3,l23ft)

2 min 34 sec to 6,000m (19,685it)

3 min 2 sec to 8.000m (26,246ft)

3 min 26 sec to 10,000m (32,8081t)

12,000m 39,370ftCeiling

Armament

Tn'o Ho-i55 30mm cannon

Deployment

None. The Ki-202 did not advance berond the design board.

41

E=gz

42 J.qp,qr,lEsE SEcnor PRorEcrs: ExpnRrunrutnL Atncnnrr on rns IJA ar'"o IJN 1939-1945

Type

Crew

Kogiken Plan I - data (estimated)

Contemporaries Arado P.530 light bomber (Germany), BeJI P-39

Airacobra fighter (US), Caudron C.670 light bomber (France), Farman

N.C.223 heary bomber (France), Messerschmitt Me 210 and 410 heary

fighter (Germany), Piaggio P.l 19 fighter (ltaly), Potez 63 heavy fighter

(France), Yakovlev Yak-2 light bomber (Russia).

Tlpe A Heary Fighter

0ne

Powerplant One Nakajima Ha-45 l8.cylinder, air-cooled radial

engine developing l,480hp for lake-offand l,460hp at 5,800m (19,028ft),

driving a four-bladed metal propeller

Rikugun Kogiken Series

Without doubt, war often provides for rapidadvancements in military technology. Thekey driver of this is the need for a weapon thatis superior to those used by the opposition. Inthe majority of cases, improvements inweapons come about because one partici-pant fields a weapon that the other partici-pants have no answer for or cannotadequately counter with currently availableweapons. This, then, spurs development ofan equal or better weapon and the cyclerepeats - an arms race! In some cases, devel-opment of a weapon does not result fromactually encountering new developments onthe battlefield. Instead, study of what couldbe encountered in the future, coupled withwhat can reasonably be advanced in terms oftechnology, provides the required emphasisfor development - in essence, an attempt tosecond-guess likely developments so that ifand when they manifest themselves theanswer will already be in place. It was the lat-ter that prompted the IJA's Rikugun Kokugi-jutsu Kenkyujo to initiate a series of studiesand plans for a host of aircraft suitable tomeet different roles.

In the summer of 1941, Kogiken (a con-traction of Kokugijutsu Kenkyujo) formed agroup headed by aeronautical engineer Lieu-tenant Commander Ando Sheigo. The taskput to Sheigo and his group of engineers wasto study Japanese aviation technology interms of what was possible at present and inthe near future. In addition, some effort wasto be spent on reviewing the aircraft technol-ogy of other countries. From the results ofthese studies, the group was to assemble anddraft proposals for aircraft to fill various rolesthat could take advantage of future innova-tion. In all there were four roles or classes ofaircraft the Kogiken group had to producedesigns for: heavy fighter, light bomber,heavy bomber and reconnaissance. Therewas a fifth class, that of high speed, but meth-ods to achieve high speed aircraft were often

incorporated into designs in the other fourclasses. In addition to Kogiken, the IJA's twobiggest aircraft providers, Tachikawa andKawasaki, were also invited to participate insome of the studies and tender their owndesigns.

A central theme in all of the Kogiken air-craft was the use of only a select group ofengines. The two most prominent were theNakajima Ha-45 and the Mitsubishi Ha-211-ll,both of which were l8-cylinder, air-cooledradial engines. At the time of the Kogikenstudy, these engines were still in develop-ment but were expected to be operational inthe very near future. Another factor concern-ing the engines was that, in some cases, thedesigns were built around the ability toreplace the radial power unit with an inlineengine without significant modifications. Theprimary inline engines were the Daimler-Benz D8601 and DB605. The former waslicence built in Japan as the Kawasaki Ha-40.

By the close of September the designswere nearing completion. Since there wereno performance requirements or specifica-tions applied to any of the classes of aircraft,this essentially left the engineers anddesigners with free rein to come up withaircraft they thought would be suitable forthe roles. In many cases this led to aircraftconcepts that featured, at least for theJapanese, unconventional mechanisms andapproaches. Each aircraft was designated as

a plan with each plan grouped by theirrespective class.

The first class, the hear,y fighter, had fourmain designs, all Kogiken creations. Twowere for a single-engine aircraft while theother two were twin-engine concepts. Thefirst was the Kogiken Plan I Type A heavyfighter. Outwardly it was a fairly conventionalaircraft. It used low mounted, thin laminarflow wings but in order to reduce drag theHa-45 engine was placed within the fuselage,along the aircraft's centre of gravity. This, in

Dimensions

Span

Length

Height

Wing area

9.32m

8.71m

3,29m

14.59m?

30.6fr

28.6ft

10.8ft

l5i.t ft?

Weights

Empty

Loaded

2,29lkg

3,l40kg

5,0501b

6,922Ib

Performance

Ma\ speed

Mar range

699kn/h

at 5,800m

599km

434mph

at 19,028ft

3i2 miies plus I hour

Armament

One 37mm Ho-203 cannon or one 20mm Ho-5 cannon and four l2.7mm

Ho-103 machine guns

KogikenPlanl-data

Type B Heary Fighter

0ne

Powerplant One Nakajima Ha.45 lS.cylinder, air.cooled radial

engine developing l,480hp for take-off and l,460hp at 5,800ni/l 9,028f1,

driving a four-bladed metal propeller

Type

Crew

Dimensions

Span

Length

Height

Winq area

9,32m

8.86m

3.68m

14.59m'?

30.6ft

29. lfr

l 2.1 ft

157.lfl!

Weights

Empty

Loaded

2,295kn1,t' 5,0591b

3,205ks i,065lb

Performance

Mar speed

Ma{ range

699kn/h 434mph

at5,800m at 19,028ft

599km 372 miles plus I hour

Armament

One 20mm Ho-5 cannon, four l2,7rnm Ho.l03 machine guns and hvo

7.7mm Type 89 Model 2 machine quns

zJfKogiken Plan I Type A heavy fighter (in the colours

of the 2nd Chutai, 48th Sentai)

IuprRrnr- JnpeNEsE Anruy 43

KogikenPlanl-data z

Uj

Tlpe:

Crelv:

Trpe A Long Range Hearl Fightet

Trvo

Kogiken Plan I Type A Long Range Heavy Fighter(in the colours of the lst Chutai, l8th Sentai).

Powerplant: Trvo ['litsubishi Ha-2 I I ll I 8.ct ]inder, air-cooled

radial engines developing 2.100hp for take-off, each driving a four

bladed metal propeller

Dimensions

Span:

Lengih:

Height:

Wrng Area:

15,97m

I 1.97m

N/A

44.99m'

i2.1ft

39.3ft

181.3f1

Weights

Empt.v:

Loaded:

Armament

One 20mm Ho-S cannon and thlee 12.imm Ho-103 machine guns

Kogiken Plan II - data

essencer put the motor approximately in themiddle of the aircraft. The cockpit was situ-ated ahead of the engine, the four-bladedpropeller being driven via a 2.5m (8.2ft) longextension shaft. For weapons, either a 37mmHo-203 cannon or a 20mm Ho-S cannon wasto be fitted, firing through the propeller hubwith two 12.7mm Ho-103 machine guns in thenose and one in each wing. Perhaps as anoversight, the design of the fighter made noprovision for cooling the internal engine.Mention was made that the fighter wouldhave been equipped with a Type 3 radio sys-

tem and provision was made to use the antic-ipated Nakajima 2,000hp Ha-145 l8-cylinderradial engine. Finally, the aircraft was to use aretractable tricycle landing gear.

The Kogiken Plan I Type B Hear,y Fighterplan used the same fuselage shape and wingsas the Type A but this time the Ha-45 enginewas moved towards the nose, needing only a

Kogiken Plan III - data

1.45m(4.7f|) extension shaft, and the cockpitwas moved to the back behind the wings.Gone was the tricycle landing gear, replacedwith a more conventional retractable maingear and tail wheel arrangement. The healyarmament of the Type A was modified for theType B with one Ho-5 cannon firing throughthe hub, four Ho-103 machine guns (two inthe nose on either side of the engine, one ineach wing) and two 7.7mm Type 89 Model 2

machine guns situated just forward of thecockpit. A Type 3 radio was also to beincluded for the pilot.

The second pair of plans fell into the role oflong range heavy fighters. In both cases, theaircraft bore a striking resemblance to theGerman Messerschmitt Bf 110 although theinfluence may have come from closer tohome in the civilian Mitsubishi Otori(Phoenix) long range communication aircraftbuilt in 1936 for the Asahi Shimbun newspa-

Kogiken PIan III - data

N/A

9,100k9 20,231b

Performance

\'lax Speed:

\'la\ Rang€:

Climb:

Ceiling:

699krn'h 434mph

1,000km 2,{85miles

8 min to 6,000m (19,685i1)

ll.500m 37.729f1

Type

Crerv

Tlpe

Crew

Light Bombei

Three

T}?e Light Bomber

Crew Three

Revised Light Bomber

Three

Powerplant Two Nakajima Ha-39 l8-cylinder, watercooled

radial engines, each developing l,760hp at 3,000mi 9,812ft ddving a

lour'bladed metal propeller

Powerplant Tno Xakajima Ha-15 18-olindet, air.cooled radial

engines, each developing l.160hp at 5,800nrt19,028fi driting a lour

bladed metai propeller

Powerplant

Tno Nakajima Ha-45 l8.o'linder, air-cooled radial engines,

each developing l,480hp driving a four-bladed metal propeller

Dimensions

Span

Lenglh

Height

Wing area

i4.59m

10.69m

3.77m

31,99m'

47.9fr

35. I fr

I 2.4ft

344.4ft.

Dimemions

Span

Lengih

Height

Wing area

l,1,l4m

10.85m

3.77m

26.59m'

l6,4tt

35.6fr

i2.4fr

286.3ft,

Dimensions

Span

Length

Height

Wing area

14.14m 46.4it

9.96m 32.711

3.77m 12.411

26.59m' 286.3ft

Weights

EmptI

Loaded

Weights

Emptl'

Loaded

Weights

Emptv

Loaded

5,303kg

i,5l(]kg

1 1,691 lb

16.556Ih

1,6i Okg

6,6tOkg

10.163Ib

l4.52lb

4.480kg 9,8761b

6,480kg 14,2851b

Performance

N{ar speed

['la\ range

649km/h

at 3,000m

t,400km

Speed

403mph \'lax speed

at 9,812ft

869 miles plus J hour ['1a: range

7l0km h

at 5,800m

l,40Okm

SPeed

44lmph l\'lax speed

at 19.02Sft

869 miles plus 1.5 hours \'lar tange

7l0kn-!-h 441mph

at 5.800m at 19,028f1

l,400km 869milesplusl.5hours

fumament

Tno 7.7mm Trpe 89 machine guns; normal bomb load of 300kg (661 lb)

to a marimum ol400kg (881 Ib)

Armament

Two 7.?mm Trpe 89 machine guns: normal bomb load of 300kg (661 lb)

to a ma'iimum oi400kg (881 lb)

fumament

Tn o 7,7mm Trpe 89 machine guns; normal bomb load of 300k9 (661 lb)

to a marimum ol.100kg (881 lb)

44 JepaxEsE Secnsr Pno;ecrs: Expenll,lnNrar- AIRcnlpr oF rHE IJA AND IJN 1939-1945

Tlpe

Crew

zi

O

Kogiken Plan V Revised Light Bomber(in the colours of the lst Chutai, 2lst Sentai).

Kogiken PlanVI - data

Hear--r Bomber

Forrr

Powerplant

Four liitsubishi Ha-21 ]ll 18.cllinder. air-cooled radial engines, each

developing 2,i00hp driling a iouFbladed metal propeller

&{!;e"e"-

per. Bothwere twin-engine designs and fittedwith the Ha-211-ll radial although the Ha-145

and the Kawasaki Ha-l40 12-cylinder, liquidcooled inline engine were also considered. Atthis time, the latter was a projected develop-ment of the Ha-40 engine, which as notedwas a licence-built version of the GermanDaimler-Benz DB60lA. They each carried a

crew of two. The Kogiken Plan I Type A LongRange Hear,y Fighter carried an armament ofone 20mm Ho-5 cannon and two 12.7mmHo-103 machine guns in the nose with a rearfiring Ho-103 for the second crewman. TheKogiken Plan I Type B Long Range HearyFighter was identical to the Type A but fea-tured a slightly different weapon fit. Itretained the two forward firing Ho-103

machine guns but would either add a secondHo-5 in the nose or swap both Ho-5 weaponsfor two 30mm cannons, perhaps based onthe 30mm Ho-155 that would eventually

KogikenPlanV-data

Dimensions

Span

Length

Height

Winc area

22,09m 72.51t

17.09m 56.lft

5.12m 16.8tt

61.00m' 656,5f1'

evolve from the Ho-S. A variation of the TypeB, the Plan II Long Range Fighter, had aslightly redesigned wing that reduced thewing area from 44.99m' (484.3ft') down to41.99m' (452f1'). A final variation, the Plan IIILong Range Fighter, reduced the crew glaz-

ing and fitted a remote controlled Ho-103machine gun in the tail.

The light bomber plans would feature anapproach that would not be repeated in sub-sequent Japanese designs. The Kogiken PlanII Light Bomber used two airframes con-nected by a wing centre section. The verticalstabilisers were connected by a single hori-zontal stabiliser. The pilot and crewman sat ina cockpit on the left airframe while a thirdcrewman had a station in the right. The mainlanding gear retracted outwards into theouter wing panels. Buried in each airframewas a Nakajima Ha-39, l8-cylinder, watercooled radial engine that developed l,760hp

Kogiken PlanV- data

Weights

Empt\,

Loaded

9,0r3kg 19,958lb

l5,l98kg 33,505Ib

Performance

\'lar speed

\'lax range

i20kmih 447mph

at 6.000m at l9,68ill

3,000km 1,864 miles plus 2 hours

Armament

One 7.7mm Tlpe 89 machine gun, one J 2.7mm Ho-103 machine gun

and fourteen 50kg (l l0lb) bombs, eight l00kg (220lb) bombs, two

250kg (551 lb) bombs or one 500k9 (1,102 lb) bomb

Kogiken Plan I Type A - data

High Speed Hean Bombcr

Four

Powerplant

Four Mitsubishi Ha.21 IJI lS-c.vlinder, air'cooled radial engines,

each developing 2.100hp driling a fourbladed melal propeller

T}?e

Crew

Tlpe

Crew

Type

Crew

Light Bomber

Three

Revised Light Bomber

Trvo

Dimensions

Span

Length

Height

Wing area

Wing loading

Poiver loading

826.33m 6,4ft

19.78m 64,9ft

5,09m i6.7fl

88.00m' 947,2ft'

2l9.7kgim' 45lbril'

2.76k9hp 6.1 lbihp

Powerplant

Two Nakajima Ha.45 l8-cylinder, air-cooled radral engines,

each developing 1,480hp drir,ing a fourbladed metal propeller

Powerplant

Trvo tr'litsubishi Ha-21 l-ll l8-cilinder, air-cooled radial engines,

each developing 2,l00hp driling a lour-bladed metal propelier

Dimensions

Span

Length

Height

Wing area

l4.l4m

10.48m

3,77m

26.59m'

46.4fr

34.4fr

12.4fi

286.3ft,

Dimensions

Span

Length

Height

Wing area

14,23m

i0.63m

3.71m

26.59m'

46.7|t

31.9ft

12.2t1

286.3ft.

Weights

Emptl

Loaded

Useful load

12.510k9 27,645lb

19.310kg 42,637]b

6,800k9 14,991 lb

Weights

Emptr

Loaded

Weights

Empty

Loaded

4,480m

6,18Oks

9,8761b

14,285lb

4,138k99,7841b

6.445kg/14,208 1b

463mph Climb

at 19.685ft

869 miles plus 1,5 hours ['lar range

684kmft 125mph

at 8.500m at 27,887it

5l5knh 320mph

at 8,500m at 27,887f1

3 min I sec to 3,500m (l l.l82lt)

6 min 3 sec to 5,000m (l6.40llt)

3,000km/1,861 miles

Performance

\'lar speed

Cruise speed

Performance

Mar speed

['lar range

71Oknh

at 6,000m

l.400km

Performance

\'lal speed 746krn,h

at 6,000m

l,400km

44Jmph

at 19,685ft

869 miles plus 1,5 hours \'la,r range

Armament

Trvo 7.7mm Tlpe 89 machine guns, 300kg (661 lb) in bombs

fumament

One 7.7mm Tlpe 89 machine gun and 250kg (551 lb) in bombs

Armament

Two 7.7mm Trpe 89 machine guns. one l2.7mm Ho-103 machine gun

and up to l,500kg (3.306Ib) ofbornbs

IupERrar- JapaNEse Anuv 45

Type

Crew

Kogiken Plan I Type B - data

High Speed Heary Bomber

Four

Powerplant four Mitsubishi Ha-21 l-ll l8-cylinder, air-cooled radial

engines, each developing 2,l00hp driving a four-bladed metal propeller

and drove a four-bladed propeller via anextension shaft. It was proposed that a sur-face evaporation cooling system be usedwhich consisted of a network of piping thatwould take the steam produced by theengines as the water circulated through themout into the wings where the cooler airwouldcondense the steam back into water that wasthen recycled through the engines. The mainbenefit from this method of cooling was thatit allowed for a more streamlined fuselagewhich increased air speed. Typical of early

war Japanese light bombers, the armamentwas light consisting of two 7.7mm Type 89

machine guns. For bombs, a regular payloadof 300kg (661 lb) could be carried with a max-imum of 400kg (881 lb).

The Kogiken Plan III Light Bomber wasbasically identical to Plan II. The main changewas the replacement of the Ha-39 engineswith the Ha-45 and the latter were situateddeeper into the fuselages requiring a .83m(2.7ft) long extension shaft. Without the com-plex cooling system of Plan II, Plan III was

Dimensions

Span

Length

Height

Wing area

Wing loading

Power loading

28.19m

20.66m

5,18m

99.00m'

221.66kg/m'

3.l2kg/hp

92.5ft

6i.8ft

I 7fr

1,065.6ft'

45.4 rb/fr,

6.9tb,hp

Weights

Empty

Loaded

Useful load

l3,0sOkg

2t,985kg

8,895k9

28,858Ib

48,468Ib

l9,6l0tb

Performance

Max speed

Cruise speed

Climb

Max range

660krnh 4lOmph

at8,500m at27,88ift

495km,/ir 307mph

at8,500m at27,887ft

4 min 8 sec ro 3,000m (9,842ft)

8 min 0 sec to 5,000m (16,404ft)

4,000km 2,485 miles

fumament Two 7.imm Type 89 machine guns, one l2.7mm

Ho-103 machine gun and up to l,500kg (3,306|b) ofbombs

Kogiken Plan II - data

High Speed Heary Bomber

Five

Powerplant Four Mitsubishi Ha-2 I l-ll I 8-cylinder, ait-cooled radiai

engines, each developing 2,l00hp driving a four-bladed metal propeller

Type

Crew

Dimensions

Span

Length

Height

Wng area

Wng loading

Power loading

27.09m 88,9ft

20.54m 67.4f1

5.33m l7.5ft

98,00m' 968.7ft1

219.70kg/m: 4slb/tf

2.8lkg,/trp 6,2lb,hp

Weights

Empty

Loaded

Uselul load

12,805k9

21,985k9

6,975kg

28,2301b

48,468tb

l5,3ntb

Speed

Max speed

Cruise speed

Climb

Max range

680krnh 422mph

at 8,500m at 27,887ft

509krilh 3l6mph

at 8,500m at 27,887ft

4 min 0 sec to 3,000m (9,842ft)

6 min 4 sec ro 5,000m (16,404ft)

3,000km 1,864 miles

Armament One i.imm Type 89 machine gun, three l2.7mm

Ho-103 machine guns and up to l,500kg (3,306 lb) of bombs

zJf

aJ

Kogiken Plan III Revked Light Bomber.

46 JapeNssr SecRnr PRo.lecrs: ExpERruEnrrl ArncRnnt oF rHE IJA AND IJN 1939-1945

smaller, lighter and faster. In addition, the

canopy for the third crewman was madeflush with the fuselage and was provided witha ventral fairing to facilitate bombing orreconnaissance duties. The propellers werefitted with ducted spinners to help cool the

engines. The Kogiken Plan III Revised LightBomber was a version of the Plan lll but withthe Ha-45 radials placed in a conventionalfashion in the nose - the ducted spinners

were left out. Another light bomber, the

Kogiken Plan V Light Bomber, shared a simi-larity to the Plan III Revised but whereas the

twin airframes were of the same length,

the Plan V had the right airframe shorter tothe point that the propeller spun behind the

one on the left airframe. The canopy for thepilot and second crewman was also length-

ened. The Kogiken Plan V Revised LightBomber broke away from the previous

designs. The twin airframe scheme wasdropped and an engine was placed in a large

nacelle in each wing. The Ha-211-ll engine

was specified but the Ha-45 could also be

used. The crew was reduced to two and the

armament was dropped to a single 7.7mmType 89 machine gun while the bomb pay-

load was lowered to 250kg (551 lb).

Kawasaki - data

Type

Crew

High Speed Healy Bombet

Four to Five

Powerplant

Tu'o Kalvasaki Ha-110 24-cvlinder, liquid-cooled inverted V engines,

each developing l.350hp driving a iourbladed metal propeller

In the heary bomber class, only one stan-

dard healy bomber design was completed by

Kogiken and this was the Kogiken Plan VI

Heavy Bomber. The fuselage was conven-

tional and was reminiscent of the solid nosed

Junkers Ju88 bombers although the Plan VI

had longer glazing over the compartment forthe crew of four. The similarities ended there.

Set into each wing was a nacelle that housed

two engines driving two propellers in a push-

pull configuration. Originally Ha-45 radial

engines were planned but the Ha-211-ll was

the engine of choice. The design could have

been adapted to take the forthcoming Mit-

subishi Ha-214 18-cylinder air cooled radial orthe Kawasaki Ha-201 which was made fromtwo Ha-40 12-cylinderinline engines mountedin tandem and was under development at the

time. Defensive armament was light consist-

ing of a single 7.7mm Type 89 machine gun

and a 12.7mm Ho-103 machine gun. A vari-

able bomb load could be carried dependingon the mission. A slight variation of the Plan VI

increased the wing area to 69.99m': (753.4f1').

There was far more activity in the highspeed healy bomber category. Here,

Tachikawa and Kawasaki made proposals as

well as Kogiken. The Kogiken Plan I Type A

High Speed Healy Bomber was similar to the

Plan lV Healy Bomber but was larger. Instead

of a conventional empennage, the Plan I Type

A used a horizontal stabiliser ending inrounded vertical stabilisers. The glazing forthe four man crew was longer and the fuse-

lagewas more streamlined. The same engine

and engine arrangement was used but the

nacelles had a slightly improved shape. For

defence, two 7.7mm Type 89 machine guns

and one 12.7mm Ho-l03 machine gun werefitted and a maximum bomb load of 1,500kg(3,306Ib) could be carried. The Kogiken Plan

I Tlpe B High Speed Heavy Bomberwas basi-

cally identical save it was larger and had alonger range. The final design from Kogiken,

the Plan Il High Speed Heavy Bomber, wasslightly smaller and lighter than the Tlpe B butadded a fifth crew member and beefed up

the defensive armament to three Ho-103

machine guns and one Type 89 machine gun.

The Kawasaki High Speed Healy Bomberwas the smallest of all the designs in the class'

Consequently, its performance was less and

carried a lighter bomb load and defensive

armament. Instead of the Ha-21 1-ll engines itused two Ha- 1 40 24-cylinder, inverted V inlineengines, which again were two Ha-40

engines placed in tandem. It was also uniquein using the 7.92mm Type 98 machine gun inits defensive armament fit. Tachikawa'sdesigns, the Plan I, Plan II and Plan III High

Speed Healy Bombers, were all variations on

the same theme with minor differences

TachikawaPlanl-data

High Speed Hearv Bomber

Six

Powerplant Four Nakajima Ha'145 l8-cllinder, air'cooled radial

engines, each developing 2,000hp driving a four-bladed metal propeller

T}?e

Crew

Dimensions

Span

Length

Height

Wing area

\\iing loading

Porver loading

24.47n 80.3f1

1i.67m 58lt

4,45m 14.6ft

85.00m' 9l4.9ft'

223.6lkgim: ,15.8lb/fl'

3.19kgihp 7,71b/hp

Weights

Emptt'

Loaded

Useful load

9,540k9

19,000k9

9,460k9

21,032 lb

41,887 lb

20.8551b

Performance

l\'lai speed

Cruise speed

Climb

\'lari range

ijS4knL'h 425mph

at9,300m al30,51lft

480krn'h 298mph

at 9,300m ai 30,51 lft

N/A

4,899km 3,041 miles

Armament

Trqo 7.7mm Ttpe 89 machine guns, one 2Omm Ho-5 cannon and up to

l,500kg (3,306lb) of bombs

Tachikawa Plan II - data

High Speed Hean Bomber

N/A

Powerplant Four Nakajima Ha-115 l8'cllinder, air'cooled radial

engines, each developing 2,000hp driving a four-bladed metal propeller

Tne

Crew

Dimensions

Span

Length

Height

Wing area

Wing Ioading

Polver Ioading

l9.l7m 62.91t

14.87m 48.8ft

N/A

48.00m: 5l6.6ft:

199.69k9m' 40.9lb/fr

3.40k9hp i,Slb/hp

Dimensions

Span

Length

Height

Wing area

Wing Ioading

Polrer loading

28.49m 93,5ft

N1A

N/A

80.00m' 861.1ft'

223.61kg/m) 45.8lb/ftr

3.3lkgihp 7.31b/hpWeights

Empty

Loaded

lxeiul load

6,1 70kg

9,590k9

3,420k9

13,6021b

21,142tb

7,5391b Weights

Empty

Loaded

Lseiul load

N/A

17,900k9

N/APerformance

Mar speed

Cruise speed

Climb

['lax range

580kn-/h

at 6,000m

6l Okn h

at 7,500m

400krdh

al 7,500m

N/A

3,000m

360mph

at 19,685ft

379mph

at 24,606ft

248mph

at 21,606f1

1,864 miles

Performance

Max speed

Cruise speed

Ciimb

Nlari range

694knr,t 43lmph

at 9,300m at 30.51 llt

490kmih 304mph

at9,300m at30,51lft

N/A

5,049km 3,137 miles

Armament ltuo 7.92rn6 T1,pe g8 machine guns, one l2.7mm

Ho-103 machine gun and up to l,000kg (2,204 tb) of bombs

IupERIel JnpaNEss ARIaY 47

Up lo l,000kg (2,204Ib) olbombs

Type

Crew

Kogiken Plan IV- data

Reconnaissance Plane

Two

Powerplant Two Nakajima Ha-45 l8"cylinder, air-cooled radial

endnes, each developing l,480hp driving a four-bladed metal propellet

between them. The key changes from theKogiken plans were the engines used. The

Plan I and Plan II bombers used four Ha-145

radials while the Plan III used only two of the

Mitsubishi Ha-21 IMB 18-cylinder, air-cooledradial engines. Of all the designs, the

Tachikawa Plan I had the largest crew com-pliment at six men.

In the reconnaissance class, three primary

designs emerged, all by Kogiken. Each ofthem simply followed trends set in the fighterand bomber classes. The Kogiken Plan IV

Reconnaissance Plane was essentially theKogiken Plan III Revised Light Bomberadapted for the reconnaissance role. Not sur-prisingly, the Kogiken Plan IV Revised Recon-

naissance Plane was derived from theKogiken Plan V Revised Light Bomber. TheKogiken Plan MII High Speed Reconrnis-sance Plane was based on the Kogiken PbnM Heavy Bomber but had a highly strearrrlined fuselage with nearly flush glazing orrcrthe crew compartment. As was typical ofearly Japanese reconnaissance aircraft tlre

Dinenslon$

Span

Lenglh

Height

Wng area

Wing loading

Power loading

14.47m

10.33m

3.74m

30.00m'

N/A

N/A

47.'ft

33.gft

12.3fr

301.3[r,

Welghts

Empty

Loaded

Useful load

4,59lkg l0,l2l lb

7,367kg 16,241 lb

N/A

Perfonnance

Max speed

Cruise speed

Climb

Max range

705km/h 438mph

at6,000m at 19,685ft

N/A

NiA

3,000km 1,864 miles plus 2 hours

One 7.7mm Type 89 machine gun

Kogiken Plan IV Revised - data

Reconnaissance Plane

Two

Powerplant Two Nakajima Ha-45 l8-cylinder, air.cooled radial

engines, each developing l,480hp driving a four-bladed metal propellet

Type

Crew

Dirnensions

Span

Length

Height

Wing area

Mng loading

Power loadinq

14.47m 4l.5lt

10.69m 35.lft

3.59m 11.8ft

30.00m'? 30l.3ft'

N/A

N/A

Welghts

Empty

Loaded

llseful load

4,426Yq 9,7571b

7,202W 15,8771b

N/A

Performance

Max speed

Cruise speed

Climb

Max range

7l5km/h 444mph

at6,000m at 19,685ft

N/A

N/A

3,000km 1,864 miles plus 2 hours

Koglken Plan II HighSpeed Heary Bomber(in the colours of thelst Chutal, 83rd Sental).

z

One 7.7mm Type 89 machine gun

48 JApeNEss SEcnrr PRo;Ecrs: ExpERttrlEntnL Atncnnpr oF rHE IJA AND IJN 1939-1945

defensive armament was extremely light forall of these planes.

None of the Kogiken aircraft would be con-structed. In part, this was due to the designsusing technology that was either in develop-ment or not yet available. Another factor wasthe unorthodox nature of many of the aircraftdrafted - one might liken the Kogiken aircraftto the results of a brainstorming with minimalrestrictions on what might be deemed possi-ble. Nevertheless, the studywas not awastedeffort and it is certainly reasonable to pre-

sume that the information provided valuabledata and worthwhile methods for subse-quent IJA aircraft. For example, the KawasakiKi-64 would use the Ha-201 coupled enginewith a surface evaporation cooling system.Another example was the Kawasaki Ki-88which was to use a fuselage-buried Ha-I40engine that drove the propeller via an exten-sion shaft. The Mitsubishi Ki-46-lll (code-named Dinah by the Allies) may have alsobenefitted from some of the aerodynamicstreamlining studies done by Kogiken.

Tachikawa Plan III - data

High Speed Heary Bomber

Forr

Powerplant

Tlro l'litsubishi Ha-21 iNlB l8-c,llinder, air-cooled radial engines,

each developine 2,200hp drivine a fourbladed metal propeller

Type

Crew

Dimensions

Span

Length

Height

Wing area

Wing Ioading

Polver loading

24.38m 80ft

l7.58m 57.71t

4,81m 15,8ft

66.00m' 710.4ftr

219.70k9/m: 45lb/ftj

4.12k9/hp 9.1 lbihpz

-Weights

Empty

Loaded

Useful ioad

17,8021b

31.967 lb

13,743 lb

8,075k9

14,500k9

6,234kg

Kogiken Plan VIII HighSpeed ReconnaissancePlane (in the colours of the

.:ti 2nd Chutai, Slst Sentai).

Performance

['lar speed

Cruise speed

Climb

tr'lar range

64lknth 398mph

at 8,500m at 27,887f1

499km/h 3lOmph

at 8.500m at 27,8871t

N/A

4,999km 3,106 miles

Armament Tlvo 7,7mm Type 89 machine guns, one l2.7mm

Ho-103 machine gun and up to 1.500kg (3,306 lb) of bombs

Kogiken Plan IV Revised - data

Reconnaissance Plane

Trvo

Powerplant

Four Mitsubishi Ha-21 l-ll l8-cylinder, air-cooled radial engines, each

developing 2,l00hp driving a four-bladed metal propeller

Type

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading

Pon'er loading

17.67m 58ft

l3.l0m 43ft

3.56m I l.7ft

61,00m' 656,5ft

N/A

N/A

Weights

Emptv

Loaded

llsefrrl load

7,420k9 16,3581b

9,9i0kg 21,8471b

N/A

Performance

Mar speed

Cruise speed

CIimb

Nlar range

775kn/h 48imph

at 6,000m at l9,685ft

N/A

N1A

3.000km 1.864 miles plus 2 hours

Deployment \one olthe Rikugun Kogiken plans progressed

be\'ond the planninq staqe.

IuprRrnr- J.rparussr ARl,ry 49

oE

z

In 1939, a specification was drawn up thatcalled for an aircraft capable of conductinglong range reconnaissance and it wasTachikawa that answered the call to providesuch a plane. However, the resulting Ki-74would find itself both a victim of developmentdelays and the changing fortunes of war.In the spring of 1939, the Koku Hombu issued

a specification for a long range reconnais-

sance aircraft that could muster a range of5,000km (3,107 miles) and a cruise speed ofat least 280mph. The reason for this request

was to provide a plane capable of operatingfrom bases in Manchuria and flying to the

west of Lake Baikal. The lake, the deepest inthe world, is located north of Mongolia, nearthe southern Siberian city of Irkutsk. Certainlythe intent was to monitor Russian and theirallied Mongolian forces, especially in the face

of Japanese defeats at the Battle of Lake

Khasan in 1938 and the Battle of Khalkhin Gol

in 1939, both at the hands of the Soviets.

Tachikawa submitted a proposal to meet the

Tachikawa K-74

Koku Hombu's specifications, drawn up by

the design team led by Dr. H. Kimura. The ini-tial design for the Ki-74 was drafted in 1939.

To achieve the required performance,Kimura selected two Mitsubishi Ha-214M

radial engines. Each engine developed2,400hp and would drive a six-bladed pro-peller. It was the pressure cabin for the Ki74that would be the stumbling block to finalis-

ing the design.Even before the Ki-74 was conceived, work

on developing a pressure cabin for use inhigh-altitude aircraft was being conducted by

Tachikawa. The purpose of such a cabin wasto maintain air pressure for the crew whenoperating at altitudes in which the outside airpressure is much lower and the air thinner.Cabin pressurisation is desired for aircraft fly-

ing higher than 3,048m (10,000ft) and doingso provided the crewwith a much more com-fortable working environment that did notrequire the use of oxygen and flight gear toprotect against the cold. It also prevented

, ..I,:rtt,:::_:t::t:,1-;ila

conditions like hypoxia, barotrauma and alti-tude/decompression sickness. Two designswere built that would test pressure cabin con-cepts. The first was the Tachikawa Ki-77.

Conceived as a plane to make a non-stopflight from Toky6 to New York, work on the

Ki-77 began in 1940. For the Ki-77, Dr. Kimurautilised a sealed crew cabin but one whichwas not pressurised. The belief was that the

cabin would keep in the oxygen but in testingit failed to meet expectations and the crewhad to wear their oxygen masks constantly.

With the poor showing of the Ki-77 cabin,

Tachikawa tested a fully pressurised cabin inthe Tachikawa SS-1. The SS-1 was a modifi-cation of the Army Type LO transport whichitself was a licence built version of the Lock-heed Model i4 Super Electra (codenamed

Thelma by the Allies). Work on the SS-1 also

began in 1940 and the one and only examplewas completed in May 1943 with subsequenttesting providing excellent data on pres-

srrrised crew cabins.

i ii1,-

50 Jep,qNtEss Sscntr PRo:Ects: ExprRtluENral AIRcRlpt or rHe IJA,qNo IJN 1939-1945

otcz-

The research into pressure cabins and theconstruction of the Ki-77 and SS-1 delayed theKi-74 project so badly that work on it washalted; once it became obvious that the cabinfor the new plane would not be ready theentire project was shelved. No prototype wasproduced.

However, towards the close of 1941, theKi-74 project was resurrected in order toinvestigate the possibility of adapting thedesign to suit the role of a long range, high alti-tude bomber and reconnaissance platform.One such bombing mission envisioned wasagainst the United States. To meet such arequirement, adjustments had to be made tothe initial reconnaissance-only Ki-74 design.Armour was incorporated along with self-sealing fuel tanks.In addition, the appropriateapparatus for bombing was introduced.Finally, the initial Ha-214M radial engineswere replaced by two Mitsubishi Ha-211-lradial engines, each producing 2,200hp.

Once the redesign was completed it was pre-sented to the Koku Hombu who approved itin September 1942 ordering three prototypes.

It was not until March 1944 that the firstKi-74 prototype was completed, but the othertwo aircraft were ready soon afterwards. Thelatter two aircraft differed from the first Ki-74only in the fact that they used the MitsubishiHa-211-l Ru engines that incorporated turbo-superchargers. With the completion of theauthorised batch ofthree aircraft, flight testingof the Ki-74 began. Handling was consideredacceptable but the Ha-211-l and the Ha-211-l

Ru engines were proving to be temperamen-tal and prone to mechanical problems. A fur-ther thirteen pre-production aircraft wereordered, but due to the severe problems withthe engines it was decided to replace themwith Mitsubishi Ha-104 Ru radials. While theHa-104 Ruwas more reliable italso developedless horsepower, in fact only 2,000hp.

IvprRrar- JapalesE Ann'rv 5l

Type

Crew

Tachikawa Ki-74 - data

Contemporaries Dornier Do217P-0 (German,v), Dornier Do3l7

(Germanv). Focke-Wulf Fw I 9 I (Cermany), Junkers Ju 86P and Ju 86R

(Cermanv), Junken Ju 388 Sttirtebeker (Germanv), BOK'l I (Russia),

De Harilland l\'losquito B,Nlk XVI (UK)

Hilh-Altitude, Long-Range Reconnaissance/Bombet

Five

Powerplant I First Prototlpe I Trvo l'litsubishi Ha'2 I I J, I 8-

cvlinder, air-cooled radial engines rated at 2,200hp ior take'off, 2,070hp

at 1,000nr3,280ft and 1,93Ohp at 5,000d16,405ft1 ISecond and Third

Prototlpes and Fourlh Pre-production Ki-741 Two N'lilsubishi Ha'21 ll Ru

l8.cvlinder, air-cooled radial engines rated at 2,200hp for take-ofi,

2,070hp at 1,000rry3,280ft and l,72Ohp at 9,500n13 l, I 70ft; I Remaining

aircraftl Tn'o l{itsubishi Ha-101 Ru l8-cvlinder, air-cooled radial engines

ratcd at 2.000hp lor take-off, l,900hp at 2.000n'6,560ft and l,750hp at

6,00Onr/19,68ift; all engines spun lout"bladed propellers

The Ki-74 as built was a mid-wing mono-plane. The pressure cabin made up themaiority of the front of the aircraft with the

bomb bay underneath. The use of the pres-

sure cabin necessitated smaller windowarrangements (as opposed to more conven-

tional glazing) and the flight deck was offset

to the port side of the fuselage. The aircrafthad a crew of five which consisted of the

bombardier, pilot, co-pilot, navigator/radiooperator and gunner. All were housed withinthe cabin with the bombardier in the nose,

the pilot and co-pilot on the flight deck and

the navigator/radio operator and gunner instations behind the flight deck. Because the

Ki-74 was expected to operate at high-

altitude where interception would be diffi-cult, the plane carried a very minimal arma-

ment consisting of a tail mounted l2.7mmHo-103 machine gun that was fired by thegunnervia remote control. Although the Ki-74

was not a dedicated bomber, it carried a

payload of 1,000kg (2,205 lb) of bombs whichwas comparable to IJA bombers then inservice.

As construction commenced on the pre-

production Ki-74s, plans were formulated toput them to use. When a number of Ki-74s

had been built, they were to be assembled

into shotai (a flight comprised of three air-

craft) and massed to conduct bombing mis-sions against the US airbases in Saipan fromwhich B-29 Superfortresses operated.

While the bulk of the Ki-74s were con-structed as bombers and reconnaissanceplatforms, another task was proposed. Withmuch of the communication between Japan

and Germany severed by the Allies, especiallyby sea, a plan was made to use a Ki-74 fornon-stop flights to and from Germany. In1944, the fourth pre-production Ki-74 wasremoved from the line and underwent modi-fications to allow it to accomplish such a feat.

Higher powered Ha-211-l-Ru engines wereutilised and fuelwas carried to enable the air-

craft to fly up to 12,000km (7,456 miles) - suf-

ficient to fly from Tokyo to Berlin. In addition,all non-essential equipment was removedand the flight deck was reallocated to the

middle of the fuselage and lengthened. The

modified Ki-74 would never make such a

flight as Germany surrendered to the Alliesbefore it could make the first attempt. The fif-

teen Ki-74s were never to see combat, in partbecause the flight testing of the twelveremaining pre-production aircraft was notcompleted before the end of Japan's part inWorld War 2.

Prior to the end of hostilities, two furthervariants of the Ki-74 were proposed. The first

adapted the Ki-74 to a transport role but this

was soon discarded. The second was the

Ki-74-ll which would have been a dedicatedbombing platform. As such, the Ki-74-ll was a

redesignwhich showed some big differencesto the Ki-74. The foremost alteration was thepressure cabin which was smaller and keptforward of the wings within the fuselage. This

allowed for a deeper bomb bay that wasneeded to carry the planned 2,000kg(4,4101b) bomb load. Due to the heavierweight, the operating range was estimated tobe 7,144km (4,439 miles) (in comparison tothe 8,000km/4,971 miles of the Ki-74).

Because of the heavier bomb load, the

Ki-74-ll was to be supported on a twin tyred

front landing gear. The wings for the Ki-74-ll

were to be more slender than the Ki-74 forhigh-altitude operation and instead of the sin-gle tail mounted machine gun, two machineguns or cannons were to be used, Two Mit-

subishi Ha-l04-Ru engines would power the

bomber, but like the transport concept, the

Ki-74-ll was abandoned and did not advancebeyond the design stage.

Thanks to its long development history the

US was aware of the Ki-74. The main thingthey did not know was the role. Thinking thatthe Ki-74 was a fighter it was assigned the

codename Pdf. It was not until May 1945 thatthe true role of the Ki-74 was discovered andso the codename was changed Io Patsy.

Dimensions

Span

Length

Height

\\jing area

lVing loading

Porver loading

26.97m

I /.b4m

5.09m

80.00m'

242,65k9m

4.39kghp

88,5fr

57.9ft

l6.7ft

86l.llfr,

49,7lbifr:

9.7lb/hp

Weights

Empty

Loaded

10.200k9

19,400kg

22,1871b

42,770tb

Performance

Mar speed

Cruise speed

iT0knxh 351mph

at 8.500m at 27,890it

101kmi'h 249mph

al 8,000m at 26,21iit

8,000km 4.971 miles

l7 min to 8,000m (26.245f1)

12,000m 39,370fr

Armament One remote-controlled l2,7mm H0'103 machine

qun in the taili l,000kg (2,205Ib) ofbombs

Deployment Did not see senice. 16 buill (3 prototlpes. 1 long

range transc0nlinental aircrait. l2 pre-production aircrall),

Survivors

Tachikawa Ki-74 (FE-2206)

This luas one olfour total K-74 b0mbers captured al the end 0f lhe r|ar,

Two rvere taken at Tachikala's facton lvhile the remainderrvere

obtained from the IJA's test centre at Tama Airfield (nowYokota Air

Base in Fussa, Japan). All lour Gee belolv) rvere listed on the l0 \'larch

1916 report. FE-2206 rvas listed as being a! AOAMC on I August 1946 but

lvas later relegated for disposal.

Tachikawa Ki-74 (FE-2207)

This example was at [']A\'lA in storage as listed on the I Augusl 1916

manifest. It $as later slated fol transfel to the Park Ridge storage facilit\

in September 1946 but no furlher trace oi FE-2207 remains and rvas

most likelv scrapped.

Tachikarva Ki-74 (FE-2208)

Like FE-2206, this Ki-74 uas housed at AOA\'IC 0n I August 1946 and

mei the same fate.

Tachikau'a Ki-74 (FEJ209)

F8"2209 rvas the third Ki-74 kept at AOAMC and joined the previous hro

aircraft on the scrapheap.

Range

Climb

Ceiling

Iczfz

52 Jepnlrlsr SrcnEr PRo:Ects: ExpERIuENtaL ArRcRanr oF THE IJA AND IJN 1939-1945

In the summer of 1942, the Koku Hombuwasformulating specifications for a fighter thatsupported a healy armament and couldoperate at high altitude. After settling on thespecifications, the Koku Hombu approachedTachikawa and Nakajima and asked eachfirm to produce a design to meet theserequirements.

The specifications for the fighter included amaximum speed of 800km/h (497mph) and arange of 3,000km (1,864 miles). The KokuHombu knew the demands were high, per-haps even impossible to obtain, and so askedTachikawa and Nakajima to put forward pro-posals to meet the demands. But they handi-capped Tachikawa by allowing Nakajima toignore the range requirement. As such, Naka-jima could concern themselves with makingtheir design fast without worrying about howfar it could operate. Undeterred, Tachikawa'sdesigners set about the task of coming upwith a concept that would achieve what theKoku Hombu asked for. What resulted was adeparture from the conventional.

It was decided that two Mitsubishi Ha-211

Ru (Ha-43 Ru), 18-cylinder, air-cooled radialengines should be used placed in the fuse-

Il,rpsnrnL JapaNssu ARN,rv

Tachikawa Ki-94-I

lage in a push-pull configuration. The keyadvantage this offered was a reduction indrag over a more conventional, wingmounted engine arrangement. Secondly, thecentreline thrust symmetry of the aircraftwould be maintained in case of engine failurewhich, in turn, allowed for nearly no loss ofcontrol. Each engine was to drive a four-bladed propeller. A twin-boom arrangementwas mated to the low mounted wings. Forweapons, a 30mm Ho-l55 cannon was fitted

into each wing while a 37mm Ho-2044 can-non was situated directly below the Ho-155,

installed in the tail boom. If required, theKi-94-l would be capable of carrying up to500kg (1,102 lb) of bombs. The Ki-941 was touse a pressurised cockpit for the pilot and fea-tured a tricycle landing gear.

Once the Ki-94-l was finalised, constructionbegan on a wooden mock-up to be com-pleted in October 1943. Tachikawa theninvited representatives from the Koku

ccz

Ecv

rq# l

53

Tachikawa Ki-94-l - data

Coniemporaries

,lunkers EF I l 2 [Germanv), l upolev A\T-23 (Russia)

Because tlte Ki-911 uas nercr buill, the specificltions arc based ot1

Tadtihaua's final rlesign plans and estinlated perfonnance,

T}?e

Crew

Healr Fighter

One

Porverplant tu'o llitsubishi Ha-21 I Ru (Ha.43 Ru) l8-cvlindcr,

air-coolcd radial enginesi rated at 2,700hp at l.r00mll.921ft. 2,800hp at

2.800mi9,186ft and 1,7;0hp at 10,;00m'34.448f1; each engine drole a

lourbladed. VDM propeller. lhc fronl hal ing a 3.3m (10.8) diametet, the

iear a 3.4m (l 1.1 it) diameter

Dimensions

Span

Lenqth

Heisht

\\ring area

\\'rng loadinl

Pouer loading

12.U6m 42,211

1;l.04ni 12.8ft

3.8{m l2.6fl

36.99m 398 2ft'

237,7ik{'m {8.ilbrlt

2.4!lkq'hp 5.5 lbrhP

l\'eights

Empt"v

Loaded

6.500ke

8.800kg

11,330lb

19,400lb

Performance

\'1a\ speed

Range

Mar range

Endurancc

l\'1ar cndurance

Climb

Ceiling

7Slknr h 185mph

at 10.000rn at 32,810ft

i.r20km 9ll miles

2,Jl9km l,r6irmiles

2.i hours

5 hours

9 min 56 sec to 10 000m (i12,80811)

11,0001im lr.93lft

fumament

Tuo 57mm Ho-101 cannons, t\\'0 37mm Ho-201 cannons, hro 30mm

Ho-15 cannons and up to 500kg (1.102]b) ofbombs

Deplolment

None. Did not advance past a mock-up

Hombu to visit and inspect the Ki-94-1. Oninspection and review, Tachikawa was to bedisappointed when the design was rejectedoutright. The Koku Hombu inspectors foundthe Ki-94-l to be too unorthodox, too complexto build and that Tachikawa's performanceestimates were optimistic.

Tachikawa, however, did not give up onthe Ki-94-l and reworked the aircraft into a

heaw fighter that was designated the Riku-

gun Kogiken Ki-104. To bcost the armament,two 57mm Ho-401 cannons were added.Unfortunately, this design was also rejected.With the rejection of the high altitude fighterand the subsequent heavy fighter revision,Tachikawa finally abandoned the Ki-94-1.

Tachikawa did not wish to let Nakajima'sdesign against the high altitude fighter speci-fications, the Ki-87, go unchallenged. Theresult was the Ki-94-ll.

zf:

Ecz==

54 Japar'-Esl Sectte't PRo.tscts: ExpnRtl,tgxral AtncRnpt oF THE IJA AND IJN 1939-1945

T'archilkarva Kit- $4- [n

)i)

Type

Crew

Tachikawa Ki-94-ll - data

Contemporaries

Focke-WullFw190Vl8tUl (Germany), Focke-Wulf Tal52H (Germany),

l\,'likoyan-Gurevich MiG-3D (Rusia), l\'liko)an-Gutevich l-220 and I-230

series (Russia),Yakovlev I-28 (Russia), Polikarpov ITP(l\'l-2) (Russia),

Yakovlev Yak-3PD and Yak-3TK (Rusia)

Because the Ki-9411 uas neDet floun, the spedfications oe based on

Tachihaua's estimated puformance,

High-Aliitude Fighter

0ne

Powerplant One Nakajima IHa-441 13 (Ha-219), l&cylinder

radial engine, developing 2.450hp for take-off, fitted with a Ru-204

turb0supercharger, dd\'ing a c0nstant speed, f0ur-bladed metal propeller

In October 1943, the Koku Hombu rejectedTachikawa's radical, twin engine, twin-boom, push-pull fighter, the company'sanswer to the Koku Hombu's request for ahigh-altitude fighter. Tachikawa was told theKi-94-l was unconventional, complex and itsestimated performance specifications wereoptimistic. The rejeciion left Nakajima's Ki-87

the sole contender for the specification,something Tachikawa was not going to lethappen.

Soon after the rejection Tachikawa utilisedthe same specifications given to Nakajima toplan a revised design. Whereas Tachikawahad to meet the Koku Hombu's 3,000m (1,864

mile) range requirement and a 800km/h(497mph) maximum speed, Nakajima onlyhad to contend with meeting the speed max-imum. Unbridled by the range issue,

Tachikawa engineers went about the task ofproducing a design capable of matching and

exceeding the Ki-87.

Knowing that the Koku Hombu wouldlikely reject anything out of the ordinary inconcept, a more conventional approach wastaken. The man behind the revised aircraftwas Tatsuo Hasegawa. Retained from theKi94-l was the pressurised cockpit for thepilot but everything else was redesigned. Thenew project used a standard configuration fora single-engine, all-metal fighter to ensureacceptance by the Koku Hombu. The power-plant selected for the plane was the Nakajima

IHa-441 l3 (Ha-219), 18-cylinder radial enginethat was rated at 2,450hp. The engine wasequipped with a fan cooled, exhaust drivenRu-204 turbosupercharger that was situated

on the underside of the fuselage. Originally, itwas planned that a six-bladed propellershould be used. However, testing showedthat when in operation a blur was created bythe spinning prop, obscuring the pilot's for-ward vision. Therefore, a four-bladed pro-peller was selected. For weapons the aircrafthad a similar cannon armament as theKi-94-1, but this was downgraded to twoHo-l55 30mm cannons and two Ho-5 20mmcannons with one of each calibre cannon fit-ted into each wing. The wings were a typicallaminar flow-type with the cockpit situatedbehind the trailing edges of the wings. As thedimensions show, the new design was fairlylarge by Japanese standards, even supersed-ing Nakajima's Ki-87 in size.

With the drafts completed, Tachikawapresented them to the Koku Hombu. Afterreview, the design was accepted as theKi-g4-ll and Tachikawa received the order toproduce a static test airframe, three proto-types and 18 pre-production aircraft. As soonas approval was received for the Ki-g4-ll,work began on the construction of the firsttwo prototlpes with the first to be completedby 20 July 1945. However, this date would notbe met as delays in production caused theprogram to fall behind schedule which, inturn, delayed the final completion of the first

Ki-94-il.Tachikawa scheduled the first flight for 18

August 1 945. However, on I 5 August 1 945, thewar ended forJapan and the Ki-94-ll was pre-vented from making any flights. The end ofthe war meant that the second prototype wasnever completed.

Dimensions

Span

Length

Height

Wng area

Wing loading

Porver loading

13.99m

I 1.97m

4.60m

27.99m]

230.45k9/m'

2.63kg/trp

45.9ft

39.3ft

l5.tfr

301.3fr,

47.2tbllt,

5.8lb,hp

Weights

Empty

Loaded

4,690k9

6,450ks

10,3401b

14,220 lb

Performance

['lax speed

Range

Climb

Senice ceiling

720kn/h 447mph

at 10,000m at 32,808ft

2,200km 1,367miles

I 7 min 38 sec ro 10,000m (32,8081r)

14,250m 46,751ft

Armament

Two 30mm Ho-155 cannons, h\'0 20mm Ho-5 cannons and either hto

30kg (66 lb) air{o"air rockets or one 500kg (1,102 lb) bomb

Deployment

None. One prototlpe was completed with a second under construction

lvhen the war ended,

Survivors

Tachikarva Ki-9111 (FE-150)

This was the first protot1pe and lvas surrendered at Tachikalva's facility

nearTokyo. Delivered to trlAl'lA lor storage and evenlual senicing, it

was listed on a i 0 March I 946 manifest of aircraft available for aviation

industry eraluation. 0n I August 1946, the Ki-9411 was still at [,1A['lA but

n0 eiforlu'as made t0 restore it although it lvas designated for display al

NAS['I, September 1946 sarv the start ol restOration rvork ior displav

pueoses and the project lvas to be completed by 18 Septembet I946.

The last kno$'n whereabouh oithe Ki-94-ll rvas in Patk Ridge in 1949.

oIozf

56 .lnpnNess SrcRrl PRo:scrs: ExpenlntsNrnl AIncRnrt oF THE IJA AND IJN 1939-1945

InrpERral hp,qn EsE ARr'tv 57

Tachikawa Ki-162 and Other IJAJet Projects

It was only after January 1945 that the Japan-

ese were given access to the very latest Ger-

man jet technology. Prior to that, access

came only after German equipment hadachieved operational status. Thus, in the

beginning of 1944, the Japanese were madeaware of the MesserschmittMe262 iet fighterand Me 163 rocket-powered interceptor longafter thev were flying. Consequently, it wasnot long before official requests for data

came from Japanese representatives inBerlin. In the subsequent negotiations theGermans were told that only the IJAwould be

building the Japanese version of the Me 262,

the Nakajima Ki-201 Karyu, the developmentof which began in January 1945. But evenbefore this, the IJA began to formulate jet

designs of its own, spurred by the release oftechnical information by the Germans.

In late 1944, the IJA initiated a study for a sin-

gle engine jet fighter and the task was given tothe Tachikawa Dai-lchi Rikugun Kokusho.

The IJA's Captain Hayashi and Captain Yasuda

assembled and led two teams to research the

concept and begin design. The one restrictionimposed was the requirememt for at least a

half hour's endurance. At this time, only the

Ne l2 series of turbojets was available. The

Ne12, a development of an earlier projectcalled the Ne 10, was found to be too healy. Alighter model, the Ne 128, was produced inlimited numbers until the Ne 20 turbolet wasfirst tested in March 1945. This engine provedto be superior to the Ne 128.

The problem facing both Hayashi and

Yasudawas that performance and enduranceon a par with a twin engine design had to be

achieved using only a single power unit. Withthe Ne 128 unacceptable, both of theselooked to the projected developments of theNe 20. These included the IshikawajimaNe 130, Nakaiima Ne230 and the N4itsubishi

Ne 330 turbojets because theywere expectedto produce improved thrust over the Ne 20.

The depiction of the 'Tachikawa Ki-I62' shownhere is displayed in the colours of the 23rdIndependent Chutai, operating in Okinawa, 1945.

J

zo

,K,,t

t

IntpERral JlpnNpss Anl,rv 59

With at least the basic dimensions of the tur-bojet in mind, each team got to work draftingtheir designs for the jet fighter. Two conceptsemerged from both teams towards the mid-dle of 1945.

Hayashi's team took the turbojet andplaced it inside the fuselage near the tail. Thefuselage was to be fairly slender in shape withthe cockpit forward of the low mounted wingswhich were to be placed about mid-fuselage.The aircraft was to have a nose intake with theturbojet's exhaust being vented out throughthe tailpipe or rear of the fuselage. Yasuda'sgroup took the turbojet and placed it on top ofthe fuselage. As opposed to Hayashi's moreslender aircraft, the Yasuda design had a

shorter and wider fuselage. As a result of theengine being on top, this eliminated the pos-

sibility of a conventional tail stabiliser arrange-ment and thus each tailplane ended in a

vertical stabiliser. Yasuda felt that with theengine outside the fuselage, the nose couldthen be used to carry armament allowing forimproved and concentrated accuracy.Yasuda's design was very reminiscent of theHeinkel He 162 Volksjdger.

At this juncture, the Volksjiiger will be dis-cussed briefly. The He 162 was designed as a

fighter that could be built quickly with semi-skilled or unskilled labour, using few war crit-ical materials and only a single turbojet. Thisenabled the He 162 to be turned out morequickly than the more complex Me 262 thenin service. The He 162 began with the Volk-sjiiger competition, but as Heinkel had theinside track with Deputy of the Reich Ministryof Armament and War Production, Karl-OttoSaur, who also happened to be the managingdirector for Heinkel, the study for the He 162

was already underway. By the time the othercompeting designs were submitted for thecompetition, the mock-up of the He 162 wasalready under construction. Little surprise thecontract for the Volksjziger went to Heinkel inSeptember 1944. On 6 December 1944, theHe 162 Vl flew for the first time.

The He 162 used a light metal monocoquefuselage with a moulded plywood nose. Thehigh-mounted wing was one piece, made ofwood and plywood skinning with metal wingtips. The two tailplanes sported vertical sta-

bilisers on their ends. Only four bolts securedthe wings to the fuselage. A single BMW003A-l Sturm turbojet sat atop the fuselagejust behind the cockpit and to help him aban-don the aircraft in an emergency, the pilotwas provided with an eiection seat. Forweapons, two MG 151 20mm cannons werefitted with 120 rounds per gun. The top speedof the He 162 was 905km/h (562mph) at6,000m (19,690ft) with a 438km (272 mile)radius at full power.

In January 1945, Erprobungskommando162 was created to field test the He 162 and onFebruary 6 I/JG 1 was ordered to convert tothe jet fighter. The He 162 was an unforgivingaircraft but in the hands of a skilled pilot it wasan exceptional dogfighter. Pilots were told toavoid combat with Allied aircraft, however inlate April and early May, I/JG 1 scored a hand-ful of aerial victories. This was tempered bythe loss of 13 aircraft and 10 pilots, mostly dueto accidents. The only other unit activated,the 1.(Volkssturm)/JG 1 at Sagan-Kupper,never received their He 162 fighters and thiswas fortunate. The pilots of this unit were toonly receive training in the He 1625, a gliderversion ofthe He 162 that had no engine, non-retractable landing gear and a rudimentarysecond cockpit for the instructor. After a fewgliding flights, the untrained pilot wasexpected to fly the jet powered He 162 andthe results would have been disastrous. A fly-able two-seat He 162 known as the Doppel-sitzer, fitted with a second cockpit for theinstructor at the expense of the cannons andammunition, oxygen system and fuel capac-ity, was not completed by the end of the warin Europe.

On 15 April 1945, the Oberkommando derLuftwaffe approved the release of specifica-tions and production data for the He 162 tothe Japanese. A delegation of IJN officialsstudied the Hel62 and visited Heinkel'sHe 162 production line in Rostock, Germany.Impressed with the aircraft, the Japanesequickly requested technical data on thefighter. Of course, by this stage of the war forGermany there was no way that physicalblueprints, production tools, jigs or a sampleHe 162 could be shipped to Japan. Instead,the only means available to rapidly send infor-mation on the jet was via wireless transmis-sion - i.e., radio. To help facilitate thetransmission of the data, CommanderYoshioNagamori used a datum line (a fixed, mea-surable line, used as a reference from whichangular or linear measurements are taken) tomeasure the He 162 and transmitted theresulting dimensions to Japan. Only a portionof the data Nagamori sent was received inJapan.

Even though parts of the measurements forthe He 162 made it to the Japanese mainland,enough was received to begin making use ofthe informaiion, filling in the gaps, revisingthe design to suit Japanese production capa-bility and compiling the drafts needed torealise the aircraft. Even though the IJN wasthe branch that obtained the He 162 data, itappeared that it would be the IJA who wouldproduce it. In addition to developing the air-craft from the data, plans were made to beginproduction.

Whether Captain Yasuda and his teamused the He 162 as their influence or arrivedat a similar design by coincidence may neverbe known. But the IJA would reject Yasuda'sfighter and instead selected CaptainHayashi's design for continued work. Per-haps it was felt that with the acquisition of theHe 162, Yasuda's design was redundant. WithHayashi's aircraft approved, he and his teammoved forward with refining the design andconstructing a prototype. However, by August1945 when hostilities ceased, none of theIJA's iet programs were ready to fly. NeitherHayashi's jet nor the Japanese version of theHe 162 would progress past the initial designstage. Only the Nakajima Ki-201 ever made itto the construction phase which, by the endof the war, amounted to a single incompletefuselage.

As a note, 'Ki-162' has been used by someas the designation for the Japanese producedHe 162. There is no historical evidence to sup-port this although it is not without precedent,such as the case with the proposed MitsubishiKi-90 that was to be the Japanese version ofthe Junkers Ju90. In addition, one may see

the full name as the 'Tachikawa Ki-162'. It isnot unreasonable to believe that Tachikawamay have played a part in assessing theHe 162 data given that the IJA had theTachikawa Dai-lchi Rikugun Kokusho andthe Rikagun Kokugijutsu Kenkyujo (also atTachikawa) at their disposal. WhetherTachikawa would have actually built the pro-duction Japanese He 162 is not known.

Tachikawa Ki-162 - data

Contemporaries

Blohm und Voss P.22li0l (Germany), Republic F-84 Thunderjet (US),

Heinkel He 162 (Germanv), Arado 8.580 (Germanv), BMW Slrahljtiger I

(Germany), Heinkel P.1073 (Germany), Henschel Hs 132 (Germany),

Anlonov SKh (Russia)

Specifirations

Very little is known olthe jet designs created bvYasuda or Hayashi and

thus no specification inlonnation has surfaced. Likelvise, since there

was little t;me to act on the He 162 data, there is no information on rvhat

the speciflcations \r,ould have been for the Japanese version though it

nould not be unreasonable t0 conclude the dimensions and

periomance nould have been similar to lhe Cerman jet.

Deplo)'ment

None. \one of the jet fighters got past the design stage

60 JnpnNEsE SEcRET PRo:ecrs: Expgnrnrsnr.qr- ArRcnapr or rus IJA aNo IJN 1939-1945

Kawanishi Baika

The invasion of the Japanese home islandswas a genuine threat to Japanese militaryplanners. Operation Downfall was the Alliedplan to launch the final blow against Japan.This consisted of the capture of Kyrlshl(Operation Olympic) that would provide thejump-off point for the invasion of Honshl,near Tokyo (Operation Coronet). Given thegeography of Japan, Japanese military lead-ership was able to narrow the likely avenuesof attack. To that end, Operation Ketsugdwasformulated. A critical component of the oper-ation was special attack units and theyneeded aircraft in mass numbers to succeedin repelling the invasion. This provided thespark for the Kawanishi Baika.

On 2 July 1944, the Kaigun Koku Hombuissued a directive to Kawanishi Kokuki K.K. toproduce a special attack aircraft. The designwas to be a replacement for the Kugisho OkaModel 11 and Model 22 as well as the specialattack version of the Nakajima Kitsuka. Thenew aircraft, called the Baika (meaning PlumBlossom), needed to be constructed from as

Imperial Japanese NaW

much non-critical war materials as possible

and be of simple design to allow for produc-tion by unskilled or semi-skilled labour insmall, scattered workshops. These demandswere a result of the relentless Allied bombingof Japanese industry and that Allied navalforces had a stranglehold on imports of rawmaterials needed to sustain the Japanese mil-itary. To meet this directive, Professors lchir0Tani and Taichiro Ogawa, both of the Aero-nautical Institute of the T6kyo lmperial Uni-versity, began to study a means to achieve therequirements of the task before them, sup-ported by Kawanishi.

The engine for the Baika, the Maru Ka-10pulsejet, was derived from the German ArgusAs 109-014 pulsejet, the technical plans for ithaving been delivered to Japan via subma-rine in 1944. The Aeronautical lnstitute of theT6ky0 Imperial University studied the designand in time developed the Ka-10. A pulsejet is

a simplistic engine that operates by mixing airthat is taken into the engine via a shuttered orvalve intake with fuel that is then ignited inthe combustion chamber. The force of theexplosion closes the intake and thus the

resulting gas can onlybe expelled through theexhaust and forward thrust is generated. This

cycle, or pulse, is repeated over and over upto 45 times per second in the case of the ArgusAr 109-014.

A pulsejet has four main benefits. Firstly,due to the simple nature of the engine it canbe easily built. Secondly, it can use low grade

fuels. Third, pulsejets offer reduced mainte-nance. Finally, they have a lower cost per unitwhen compared to other engines. However,the pulsejet does have three major flaws - itis not fuel efficient and, due to the operatingnature of the engine, it is noisy and generates

significant vibration.The choice in using the pulseiet for the

Baika was clear. With the situation for Japanbeing what it was in late 1944 and into 1945,

the Ka-10 offered a far less complex enginethan a turbojet or piston engine. This meant itcould be built in greater numbers by unskilledor semi-skilled labourers. Because it coulduse low grade gasoline it put less of a strain onthe supply chain struggling to provide morerefined aviation fuel. Tani and Ogawa did findthat the Ka-10 suffered from having a short

z!

U

InrpsRrer- Jeperupse Navv 6l

selvice life in regard to its fuelvalve. They alsohad concerns that the high noise of theengine would provide enough advance warn-ing that countermeasures could be set or sent

up to combat the Baika. Finally, it wasrealised that the vibration caused by the

engine would put a strain on the aircraft, per-

haps causing failures in the aircraft's struc-

ture. The benefits, however, outweighed the

disadvantages and work on the Baika designproceeded.

A meeting was called on 5 August 1945 tobe held at the Aeronautical Institute of theTdkyd Imperial University. It was attended byAdmiral Wata and Admiral Katahira from theKaigun Koku Hombu, professors Naganishi,

Ogawa and Kihara of the Aeronautical Insti-

tute, and Chairman Katachiro of Kawanishi.In the discussions, the Baika was selectedover the rival Krigisho Oka Model 43B, the lat-

ter being seen as too complex to build innumbers quickly, especially since it used theNe 20 turbojet. Some revisions, specifically insimplifying the design, resulted in two ver-

sions of the Baika being discussed. As theBaika was to be used to defend the homeisland, launch rails were to be constructedthat would use a solid fuel rocket to hurl theBaika into the air. The second version incor-porated a simple landing gear and it wasdecided that the Baika with the landing gear

would be used for training pilots before theyconverted to the rail launched Baika. After all,given the mission of shimprl attacks on Alliedinvasion ships, the pilot would not be return-ing and would have no need of landing gear.

At the conclusion of the meeting, Kawanishiwas given an order for one Baika prototypeand ten two-seat trainers. The company wasgiven a deadline of September to have thefinalised design completed as well as a pro-duction plan finished. Mass production wasto begin in October 1945.

Kawanishi was given the following specifi-cations for the Baika:

length of no more than 8.5m (27.8ft)

height of no more than 4m (l3.1ft)

width, with folded wings, of no more than

3.6m (1 1.8ft)

speed, with the Ka-l0, must be at least

463kn/h (287mph) at sea level

a ceiling of 2,000m (6,561ft)

range of at least l30km (80 miles)

100kg (220Ib) explosive payload

As the Baikawas developed, three versions ofthe aircraft emerged. Two were similarexcept for the cockpit placement. Despite the

initial direction that the Baika would be raillaunched, all versions used landing gear. The

first version, or Type I, had the Ka-10 pulsejetdirectly above and behind the cockpit - this

resulted in a fairing that enveloped a portionof the front support strut for the engine. Thesecond version, the Type II, moved the Ka-10

further back, eliminating the need for the fair-ing. The final version, or Type III, placed theKa-10 below the fuselage instead of above it.

With the first two, the ad.iustment of thepulsejet may be due to maintain the centre ofgravity on the aircraft. Facilitating pilot egress

was likely not the reason for the move. Theneed for landing gear suggests that raillaunching was not the only means to get theBaika airborne. Towing or using rocket boost-

ers may have been considered or the use ofthe landing gear may have simply been fortraining use only. It is probable that the land-ing gear could be iettisoned to improve aero-

dynamics. The Type III, with the underslungengine, would suggest that it was to be car-ried by a parent aircraft much in the mannerof the Oka in addition to rail launching. It isunknown what the two-seat trainer versionwould have looked like. It is not unreason-able to assume that the warhead would havebeen removed and a second cockpit installedwith ballast simulating the warhead, muchlike the Krlgisho oka Model 43 K-l Kai, thetwo-seat trainer for the Oka.

Initially, the Baika featured 8mm of armourprotection for the pilot and although this onlyprotected his back, it was a means to allowfor some modicum of defence against inter-ceptors firing from behind rather than groundfire. However, this was changed and thearmour was removed, allowing for anincrease in the warhead size up to 250kg(551 lb). While this did result in a reduction ofrange, it was not seen as a detriment given

that the likely engagement distances wouldbe rather less than 130km (80 miles).

On 6 August 1945, another meeting on theBaika was called. Masayama Takeuchi of theKaigun Koku Hombu had concerns in regardto its construction and sought to have theBaika built from as little war-critical materialas possible, meaning that wood would beused wherever possible. The Baika also hadto have passable handling characteristics inthe air to give the pilot the best opportunity tostrike his target. Beginning on 8 August 1945,

a team of 60 men was assembled at Kawan-ishi to oversee development and productionof the Baika to be led by engineer Tamenobu.It all came too late for on 15 August hostilitiescame to a close and the Baika project cameto an end before it had left the drawing board.

As anote, some sources make the case thatthe German Fieseler Fi 103R Reichenberg,

the manned version of the Fi 103 (V-1), wasan influence for the Baika. There are US intel-ligence reports which indicate that the Japan-ese were well aware of the Fi 103 by October

1943 and that one was obtained in November1944. These reports also suggest that theJapanese were very interested in the airlaunching techniques for the weapon.Another report indicates that the Japanesealso knew ofthe Reichenberg project. A 1946

USMF report shows the Baika as a copy ofthe Fi 103R. Finally, a manifest of cargo on theJapanese submarine I-29 (the same that car-ried data on the Messerschmitt Me 1638 andMe262; see the Mitsubishi J8M Slusui chapterfor more information) listed a single Fi 103

fuselage as being onboard. The contempo-rary illustrations of the Baika today (including

the one here) are derived from the drawingsof the aircraft made by Technical Comman-der Eiichi Iwaya in the 1953 Japanese bookKoku Gijutsu No Zenbo. Whether the Baikawas truly inspired by the Fi l03R or was sim-ply an independent design may never beknown for certain.

Kawanishi Baika - data

Contemporaries

Fieseler Fi 103R Reichenberq (Germany)

Tlpe SpecialAttackAjrcraft

Crew One

Powerplant

One I'lanr Ka-10 pulse jet; rated at 360kg (i91lb) olthrust

Dimensions

Span

Length

Height, unknown

\Ving area

6.58m 21.6ft

6.97m 22.91t

up to 3,99n/l3.llt by requirements

7.58mr 81.6ft1

Weights

Emptl

Loaded

Armament

1,653 lb

3,152 lb

750k9

1,430ks

One 250kg (551 lb) rvarhead

Performance

I\'lrx speed

Cruise speed

Range

Climb

Ceiling

Fuel capacih

648kn/h

at 2.000m

185kn,h

at 6,000m

278km

2,000m

600 iitres

402mph

at 6,56lft

30lmph

at l9,68iit

172 miles

3 min 55 sec to 2,000m,'6.561|t

6,56tfl

158 gallons

Deplolment

\one. Did not advance past the drawinq board,

62 JapaNsss StcnEr PRoJECTS: ExprRrrurENteL AIRcRnrr oF rHE IJA AND IJN 1939-1945

Kawanishi HllK Soku

By 1944, Japan was hard pressed to fuel her

'uvar machine with the raw materials it des-perately needed. Being an island, only twomeans were available for Japan to receiveore, fuel and other vital materials from whatholdings Japan had left. The first was by sea

and the second was by air. The sea route wasfraught with risk due to the US Nary and Alliedsubmarine and warship presence in thePacific. Thus, delivering cargo by air, whilealso not without risk, appeared a betteroption, despite the lower tonnage capacity incomparison to sea-going freighters. There-fore, the Kaigun Koku Hombu asked Kawan-ishi to design what would be one of only ahandful of dedicated transport seaplanes ofthe war.

The IJN knew full well the impact the US

Nar,y's unrestricted submarine warfare doc-trine was having, which made merchantships the primary target. By the end of thewar, 1,200 Japanese merchant ships hadbeen sent to the bottom along with five mil-lion tons of cargo. In part this was due to poorconvoy methods and protection by the IJN,

but also because the US had broken theJapanese merchant marine cipher (the 'marucode'). Hence, moving cargo by sea wouldmore often than not result in the shippingbeing located and sunk. ln 1944, shippinglosses were at their highest and by 1945,

while they did decline, it was because fewerships were moving on the open ocean.

The desperation for fuel and other warmaterials was illustrated by the IJA's KokusaiKi-105 Otori (meaning Phoenix), the twin-engine version of the Kokusai Ku-7 Manazuru(Crane) transport glider. The IJA planned touse the Ki-l05 as a fuel tanker which wouldfly from Japan to the Sumatra oil fields inIndonesia, load up with fuel and then return.However, to make the return trip the Ki-l05would consume some 80 per cent of the fuelby the time the aircraft returned to Japan. TheIJN looked for a better solution with a largetransport capable of carrying a significantcargo load. Because a large expanse of oceanhad to be crossed in order to reach what fewterritories the Japanese still held, the IJN

desired to have a seaplane to do the job. InJanuary 1944, the IJN asked Kawanishi todevelop such an aircraft.

Kawanishi was a leader in flying boatdevelopment and had gained most of itsexperience in designing large sea going air-craft. Two of their most successful designswere the Kawanishi H6K (codenamed Mauisby the Allies) and the H8K (Emily), with thelatter arguably the best flying boat of World

War 2. The company was also not lacking incargo flying boat design having modified the

H6K to serve as a transport as the H6K2-L andH6K4-L. Even the HSKwas adapted as a trans-port, the H8K2-L Seikl (or Clear Sky). Kawan-ishi had also been working on the design ofthe K-60, a long-range transport flying boat.

With these credentials, Kawanishi was able

to capitalise on their knowledge to begin the

design of the Hl1K Soku (Blue Sky) for the

IJN.Kawanishi was instructed by the IJN to use

as muchwood as possible in the constructionof the Soku since a flying boat of such size

would have consumed a large amount of pre-

cious alloys needed for other aircraft such as

fighters. Within Kawanishi, the Soku wascalled the I(X-8 and the initial design draftwas processed rapidly. The aircraft drewheavily from the H8K being a high-wing, can-tilever monoplane but overall, the Soku wasmuch larger. The keel of the Soku was nearlyidentical to the H8K. To power the flying boatfour Mitsubishi MK4Q Kasei 22 (Ha-32-22)

radials, each developing 1,85Ohp, wereselected with two perwing. As ordered by theIJN, both the fuselage/hull and the wingswere to be built of wood and under each wingwould be a non-retractable float. The Sokuhad two decks. The lower deck could accom-modate up to eighty fully equipped soldiersincluding a number of vehicles or a compa-rable amount of cargo. A smaller, upper deckhoused quarters for the crew of five. The

main departure from the H8K transports wasthat the Soku utilised a split nose that washinged to allow the two nose sections to beopened outward to each side of the fuselage,providing ready access to the lower deck.This facilitated easier loading and unloadingincreasing the speed and ease of these pro-cedures. As a measure of protection the Sokuwas to be fitted with three 13mm Type 2

machine guns.Kawanishi presented the KX-8 to the IJN

and the design was accepted. Authorisationwas given to construct a full scale woodenmock-up of the Soku now designaied theHl 1K1 for inspection before Kawanishi couldproceed with the actual prototype. Construc-tion of the mock-up commenced at the portof Komatsujima in the city of Komatsushimaon the island of Shikoku (the smallest of thefour main islands making up Japan). This

area was selected by Kawanishi because ithad access to the Seto Inland Sea which,once the prototlpe was built, would beneeded to undertake sea and flight trials.Unfortunately for the Soku, the deteriorating

IupEnrnl JapaNesE Navv n.1

war picture saw delay after delay affect theconstruction of the mock-up. To add to theproblem, Kawanishi was instructed by the IJN

in 1945 to reduce production of the H8K andinstead, concentrate on building the Kawan-ishi NlK2-J Shiden-Kai fighter. Together,these factors would see the mock-upapproaching its completion in April 1945,

well over a year after the design had beeninitiated.

On I April 1945, bombing raids conductedon targets along the Seto Inland Sea saw thenearly completed Soku mock-up destroyed.With this loss, all further work on the Sokudesign was shelved.

Kawanishi HllK Soku - data

Contemporaries

Blohm und Voss BV222 Wking (Germany), Blohm und Vos BV238

(Germany), Dornier Do 214 (Germany), Boeing C-98/B-134 (US),

Consolidated PB2Y-3R Coronado (US), Martin JRM-l Mars (US), Martin

PBM{R Mariner (US), SikorskyVS"44 Lrcalibur (US), Convair R3Y

Tradewind (US), Short Sandringham (UK), Short Solent (UK)

Because the Hl I Kl uos not built, the specifications giDen arc estim1tes

made by KauanishL

Transport Flying Boat

Five

Powerplant

Four Mitsubishi MK4Q Kasei 22 (Ha-32-22) l4-cylinder, air-cooled ndial

engines developing I,850hp for take-off, l,680hp at 6,886ft and l,550hp

at 5,500m/18,044ft; each engine drove a 4.3m (14, lft) diameter, four-

bladed, altematinq stroke propeller

Type

Crew

Dinensions

Span

Length

Height

Wing area

Wng loading

Power loading

47.97m 157.4ft

37,70m 123.7fi,

12.55m 4l.2it

289,95m'? 3,12lft?

l56.i2lg/mr 32.1 lb/ft)

6.l2k9hp l3.slb,ftp

Weights

Empty

Loaded

Useful load

26,405ks 58,2131b

45,550kg 100,4201b

19,095kg 42,0971b

Performance

Mar speed

Cruise speed

Landing speed

Range

Climb

Ceiling

4i0krnt' 292mph

at 5,000m at 16,404ft

369km/h 229mph

l44km/h 89mph

3,890km 2,417 miles

I I min 30 sec to 3,000m (9,842tt)

N/A

zJf

UJ

Armament

Three l3mm Tlpe 2 machine guns with 200 rounds of ammunition per

gun

Deplolm€nt

None. The Hl I Kl Soku did not advance past the mock-up stage

64 Jnpnnrsr SscRer Pno.lrcrs: ExptRrn,teNtaL AtRcRapr oF rHE IJA AND IJN 1939-1945

There are a few Japanese wartime aircraftsuch as the Kugisho Tenga jet bomber thatremain shrouded in mystery to this day. TheKawanishi K-200 most certainly falls into thiscategory, a design that had it proceededwould have resulted in the first turbojet pow-ered flying boat.

Very little is known of the genesis of theK-200. Kawanishi may have beenapproached by the IJN to initiate the projector Kawanishi may have undertaken thedesign themselves to see if a flying boat couldbe constructed using the new jet enginesbeing designed following the success of theNe 20 turbojet. Towards the close of the war,Kawanishi was developing two other largeflying boats: the Kawanishi K-60 and theKawanishi Hl lK Soku. Both of these were atthe behest of the IJN so it may not be unrea-sonable to assume that the IJN also askedKawanishi if they could add a jet powered fly-ing boat to the mix. Exactly when Kawanishibegan to study the prospect of the K-200 is notknown though 1945 is the likelyyear.

Depending on the source, the K-200 waseither to be the replacement for all IJN flyingboats in service or the K-200 was to be a car-rier for a Japanese atomic weapon. The for-mer assumption would likely have dependedon the performance of the K-200 had it beenbuilt. Certainly the prospect of the K-200 didnot deter other flying boat projects such as

the K-60 nor improvements of the H8Kalready in use. If the K-200 was to be such areplacement for operational flying boats andproved superior to them, it most likely wouldnot have entered widespread service until1946. As far as the latter, the K-200 would haveneeded capabilities that exceeded flying boatdesigns then in service in order to serve as a

means to drop an atomic weapon on the US.

It has been suggested that the NakajimaFugaku was also devised to carry an atomicweapon but there is no support for thisnotion. The same may be said for the K-200.

One can speculate as to whether the K-200

would have been any more successful in pen-etrating US coastal defences than a high flyingbomber. As we shall see, the K-200 may havehad a flaw that would have made any suchuse all but impossible.

What the definitive shape of the K-200 wasto be is open to conjecture. Certainly Kawan-ishi would have utilised their successes withthe H8K and to a lesser degree with theKawanishi H6K (codenamed Mouls) as afoundation for the K-200. As such, it is likelythat the hull design would have followed asimilar pattern. One speculative illustration of

IupnRrnr. .hplllEsE Nlvv

Kawanishi K-200

the K-200 shows a hull not unlike the H6K butdeeper, though not to the extent of the H8K. Aconventional tail akin to the H8K was usedbut the horizontal stabilisers were mountedhalfway up the vertical stabiliser. The wingsappeared very similar to the HSK and were fit-ted to the hull in a like position, this being onthe top of the hull and, at least for the K-200,

nearly central mounted on the hull. Interest-ingly, the K-200 was illustrated with fixedwing floats, which contrasted with theretractable floats used by the H8K3 as a

means to increase speed. Perhaps such a

modification would have been consideredfor the K-200 as well.

The K-200 is shown as having an armamentlayout similar to the H8K1. If this was the case,

a Type 99 20mm cannon was fitted in a tailturret and in the top mounted turret forwardof the wings. On either side of the forwardbow was a blister that would have beenarmed either with the Type 99 cannon or aType 92 7.7mm machine gun. Finally, a Type99 cannon would have been fitted in the bow.The K-200 was also probably able to carry apayload of bombs, depth charges or torpe-does.

As far as propulsion, the K-200 was to use

six turbojets. Theywere to be mounted on topof the wings with each turbojet housed in aseparate nacelle. Grouped in sets of three, theengines were fitted to each side of the hull ontop of the wings. The reason for this was tominimise the amount of sea spray ingested bythe engines during use. If the K-200 was ofsimilar dimensions to the H8K, then the tur-bojet engines would have to move somethingin the region of 24,948kg/55,000Ib of weightwhen the K-200 was fully loaded. If the Ne 330

turbojet was the engine of choice, all sixwould produce a combined thrust of7,800kg/l 7,196Ib. This may have been suffi-cient to give the K-200 a speed superior to theH8K2, which topped out at 467km/h(290mph).

Where the K-200 may have come up shortis in terms of its range. Six turbojets wouldhave required a significant amount of fuel inorder to give the flying boat a useful opera-tional radius. As an example, the Ne 20 turbo-jet consumed around 740kg (1,630Ib) of fuelper hour. The Nakajima Kitsuka, which usedtwo Ne 20 engines, carried a maximum of1,447kg (3,190lb) of fuel (and without droptanks only 723.5k9/1,5951b) and therefore, atits cruise speed, could muster a 824km (512

mile) operational range. If the Ne 330 con-sumed approximately 2,535k9 (5,588Ib) offuel per hour at full thrust, then six would

require at least 1 5,028kg (33,528 lb) of fuel forapproximately one hour of operation at max-imum speed. Flying at a cruise speed would,of course, extend the operating range.Options to attempt to save weight may haveincluded removing any armour, stripping thedefensive armament and/or constructing theaircraft from wood as was the plan for theHllK Soku. Even with such measures theK-200 would have been hard pressed tomatch, let alone exceed, the range of the H8Kor more conventional piston engine flyingboats.

It is not known how far Kawanishi studiedthe feasibility of the K-200, if at all. Withresources allocated to the H8K, the HllKSoku and the K-60 among other projects,

Kawanishi designers may have put the K-200

to one side pending availability of turboietssufficient to warrant the effort in developingthe flying boat. Aside from anything else, evena reliable turbojet such as the Ne 20 couldonly muster four to five hours of operationbefore it would suffer from problems. It mayhave been seen that preliminary perfor-mance estimates fell short of expectationsand offered no significant advantage overdesigns currently in use or projected to enterservice. Finally, a lack of materials necessaryto construct the K-200 may have played a rolein sidelining the design; the engine and con-struction material issue saw the K-60 groundto a halt and this mayverywell have extendedto the K-200. Regardless of the reasons, theK-200 would never be anything more than aconcept.

As a side note, following the war it wasplanned to construct a civilian version for useby Japan Airlines.

Kawanishi K-200 - data

Contemporaries

Beriev R-l (Russia), l'larlin P6\,1 Seama$er (US)

Specifications

There is n0 exact information available on the Kan'anishi K-200.

Deployment

None. The K-200 existed only as a concept orpaper design.

65

The K-200 depicted here is basedon a contemporaryJapaneseillustration of the flying boat whicbitself is a conjecture on what theK-200 may have looked like.

JApANESE SrcREr PRo:Ects: ExpgntllENreL AtnCnnrr oF rHE IJA AND IJN 1939-1945

Every aircraft creator seeks to reduce drag intheir designs. The definition of drag is theforce that resists movement through a fluid,which, of course, includes air. The more drag,the slower the aircraft moves through the airdue to the resistance. Drag cannot be com-pletely removed from a design, but even inthe earlyyears of aviation various methods forminimising drag were investigated and manydifferent solutions were tried. Not surpris-ingly, such applications were valued by thoseproviding the military with aircraft and inJapan, prior to the outbreak of hostilities withthe US, the Dai-lchi Kaigun Kok[ Gijutsu-showould study such efforts in an attempt to pro-duce fast flying aircraft.

Form drag is the component caused by theshape of the body moving through the air.Therefore, when designing an aircraft theform and shape of the plane is one of themost important factors a designer has to con-sider. The wider the cross section, the moredrag is produced. Having significant formdrag results in lower speeds because thefaster the aircraft moves through the air, themore drag force is applied to the aircraft.

KugishO High-Speed Proj ects

Therefore, in order to realise higher airspeeds, the designer must take steps toreduce drag and thereby lower the amount ofdrag force slowing the aircraft down.

Before World War I some aircraft design-ers appreciated the need to reduce drag. Thisoften took the form of fuselages that hadclean lines in an attempt to remove protru-sions and also to streamline propeller hubs tohelp them cut through the airmore efficiently.The best example would be the 1912 Deper-dussin that won the Gordon Bennett race inChicago, Illinois, which became the first air-plane to exceed 16lkm/h (l00mph) (in 1913

a later model of the plane would achieve205km/h (l27mph).

At the beginning of World War I , few of themajor combat aircraft utilised significant dragreducing methods. Exhaust stacks, radiators,protruding machine guns, wire bracing, strutsand engines only partially cowled predominated. One of the few exceptions was theMorane-Saulnier N'Bullet'. Nevertheless, therapid pace of combat aircraft developmentduringWorldWar 1 sawdesigners looking forways to increase speed as a means to get the

edge over the enemy. The Albatross D seriesand the Roland 'Walfisch'would epitomisethose efforts.

Following World War 1, the resurgence inair racing such as the Schneider Trophy inEurope and the National Air Races in Americasaw rapid advances in aerodynamics anddrag reduction to produce fast flying racingaircraft for competition. Aircraft such as theCurtiss R2C-1 Na'"y Racer, the AdolpheBernard'Ferbois' (capturing the world speedrecord of 45lkm/h (280mph) in 1924), GlosterIII, Supermarine S.5, Kirkham-Williams Racer(which, unofficially, flew to a speed of51gkm/h (322mph) in 1927) and the Savoia-Marchetti S.65 typified high performance raceaircraft. The benefits of these innovationswere not lost on military aircraft designers.

With the war clouds looming on the hori-zon, the seeds planted by the air racers of the1920s and early 1930s were germinating inthe aircraft used by the air forces of the majorpowers. Designs by Curtiss for the US ArmyAir Force were influenced by the Curtiss rac-ers while the retractable landing gear of the1920 Dayton Wright RB racer would become

The DB 60lA engine aircraft,

z

o-Joezzo

In'tprRrer- Jnpar{Ese Nnvy

The NKIB engine design,

b/

a hallmark of Grumman aircraft such as the

F2F. In Great Britain, R. J. Mitchellwould drawheavily from his experience designingSchneider Trophy racers to build the Super-

marine Type 300 which would eventuallyevolve into the Spitfire. In Italy, Mario Castoldi,lead designer for Macci, would turn his skillsin constructing racing aircraft to producingfighters for the Regia Aeronautica with typessuch as the Macci C.202 Folgore.

Japan, like other countries, sought to pro-duce racing aircraft and planes designed tobeat world speed records. An early examplewas the Emi 16 Fuii-go built by Itoh HikokiKenyusho (ltoh Aeroplane Research Studio),which from 1920 was used in Japanese com-petitions, and the contemporary racing air-

craft from Shirato Hikoki Kenkyusho.

Kawanishi was not far behind with the K-2

speed racer which, despite extreme mea-sures to minimise drag, suffered from a drag-

inducing radiator mounted on top of the

fuselage. The K-2 achieved an unofficialspeed of 258km/h (160mph) in a flight madeon 31 July 192 1 . Other refinements in aerody-

namics could be seen in the Kawasaki Ki-28

of 1935 which, despite its advantages inspeed, climb and acceleration, was not suc-

cessful in attracting IJA contracts.In 1 938, a group of designers sought to pro-

duce a high-speed aircraft to challenge theworld air speed record. Once war had brokenout this aircraft, called the Ken lll, was soon

taken over by the IJA. Redesignated the Ki-78,

its development was continued underKawasaki. During this time, it may have beenthe IJN who decided to conduct its own stud-

ies of high speed aircraft with Kugishoassigned the task of doing so. Whether thestudies were initiated in response to the IJA's

own high-speed aircraft project is unknownbui the prevalent aircraft design philosophy ofboth the IJN and the IJA prior to the war wasof speed, agility and range at the expense offi repower, durability and protection.

Kugisho examined over half a dozenaspects of aerodynamics in order to producedata on what would be needed to realise an

aircraft capable of significant speed. One

area of research was the main wings. The

shape of a wing is one of the more criticalaspects of aircraft design. Factors such as

wing loading, expected air speeds, angles ofattack and the intended use of the aircraft allinfluence how the wing is shaped. For highspeeds, a low aspect ratio wing is often con-sidered. Typically, these are short span wingswith the benefits of higher manoeuvrabilityand less drag. In addition, having a backwardsweep to the wing also lowers drag. The dragmost associated with wings is termedinduced drag, which is caused by wing tip

vortices that change how the air flows overthe wings. This change results in less and less

lift which then requires a higher and higherangle of attack to compensate and, from this,induced drag results. Elliptical wings offerless induced drag than more conventionalstraight wings. However, low aspect ratiowings are more prone to larger vortices

because they cannot be spread out across alonger wing. Krlgisho's study on wing shapeswas the likely result of testing various airfoilsin a wind tunnel to determine their effective-ness and record the results.

Another aspect Klgishd engineers reviewedwere the merits and flaws of using either aninline or a radial engine and how each tlpereduced the form drag. In both cases the engi-neers drew up two concept aircraft and eachmade use of streamlining. Streamlining is theprocess of shaping an object, in this case, afuselage, to increase its speed by reducingthe sources of drag. One concept used the1,159hp Daimler-Benz DB 601A, a 12-cylinder,

inverted-V, liquid-cooled, inline engine. This

engine would be licence built for the IJN as

the Aichi AEl Atsuta (the 'A' stood for Aichi,'E' for liquid-cooled and 'l' for first liquid-cooled engine; Atsuta was a holy shrine inAichi Prefecture) and for the IJA as the Ha-40

before it was renamed the [Ha-60] 22. Thesecond concept aircraft used a 1,000hp Naka-

iima NKlB Sakae 11 whichwas a 14-cylinder,air-cooled, radial engine. This engine was a

licence version of the Gnome-Rhdne l4K Mis-tral Major (in engine nomenclature, the 'N'was for Nakaiima, 'K' for air-cooled, '1'as thefirst air-cooled engine, while the 'B'was forthe second version of the NKl; Sakae meansprosperity in Japanese).

Kugisho would use the same basic air-frame for the engine study. It consisted of awell streamlined fuselage with the pilotmounted in a cockpit set behind the wing andjust forward of the vertical stabiliser. This stylewas found in a number of racing aircraft suchas the American GeeBee Rl and Geebee Z.

Both used a standard tail-siiter configurationfor the landing gear. The concept equippedwith the DB 601A engine had a fuselage shape

that was not unlike the Kawasaki Ki-61 Hien(meaning Swallow; codenamed lony by the

Allies) which would appear in prototype formin December 1941 . The wings were mountedlow on the fuselage. The fuselage appear-

ance was due to the inverted-V engine which,by design, offered lower height, weight and

lengthwhen compared io more conventionalmotors. By contrast, the concept using the

NKlB had a more ovoid fuselage shape, the

result of the height of the radial engine. To

maintain the aerodynamic streamlining a

large spinner was used. Also, in contrast to

the DB 601A equipped design, the wings weremounted mid-fuselage.

Kugishd would not produce any direct pro-totype aircraft from either concept. lnstead,the results of the various studies were likelykept available as reference for engineers toaccess as a means of obtaining data on theaerodynamic problem. Perhaps Krlgish6 inhindsight considered themselves fortunate tonot have expended additional expense andeffort in producing working prototypes given

the failure of the IJA's Ki-78, a program thatlingered on into 1944 and never met its designgoals.

The DB 601A engine aircraft is shown in thecolours originally used on a Mitsubishi A6M3,

serial 3032, tail code V-190 of the TainanKokutai. It was found on Buna Airfield on 27

December 1942 in disrepair. lt was a presen-

tation aircraft donated by Sadahei, a civilianvolunteer group. The Hukuko number was874. The NKIB engine design is painted in thestandard training orange used on prototypes

and trainer aircraft.

Kugisho High-Speed Aircraft Project - data

Contemporaries

Messerschmitt ['le 209 (Cermanv)

High.Speed Aircralt

0ne

Powerplant OneDaimler-BenzDB60lA,l2-c\'linder,inverted-V,

liquid-cooled, inline engine developing l,l59hp or one Nakajima NKIB

Sakae I I 14-c$inder, air-cooled, radial engine developing 1.000hp

Twe

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading

Polrer loadinq

N/A

(DB60lA) 6.91m

(NKIB) 6.97m

N/A

N/A

N/A

ti/A

22.711

22.91r

Weights (approximate)

Empty (DB601A) 1,600kg

(NKlB) l,289kg

Loaded (DB60lA) l,900kg

(NKtB) l,6s9kg

Fuel&oiln'eight (DB60lA) 2lskg

(NKIB) 270k9

3,527.31b

2,841.7 lb

4,188.7 lb

3.657.41b

473.9Ib

595.2Ib

Performance

Mar speed

Range

Climb

Ceiling

\1A

\1A

\/A

N/A

Deplolment

None. Both Kngisho designs existed on paper only

68 JeplruEst SEcnsr PRo.lEcrs: Expnnnrlrvral ArRcRalr on rHe IJA nno IJN 1939-1945

Kugish6 M)ff6

The development of the KyushuJTWShindenwas an ambitious undertaking. CaptainMasaoki Tsuruno, the man behind the Shin-den, needed to confirm the handling charac-teristics of a canard aircraft beforeproceeding further with the plans and con-struction of the J7W itself. To do this, he com-missioned Klgish6 to design and build threegliders that were based on his JTWI aircraftplans. The result was the MXY6.

Krlgisho drew up the design of the MXY6

with the assistance of Captain Tsuruno. Con-structed entirely of wood, the MXY6 featureda slightly swept wing, vertical stabilisers fittedinside of the wing ailerons and canardsmounted along the nose of the fuselage. Thebraced tricycle landing gear was fixed andprovided with suspension. Once the MXY6

was finalised, construction was entrusted toChigasaki Seizo K.K. and they had completedthe three gliders by the fall of 1943. Flight tri-als got under way soon thereafter and theMXY6 was found to have good handling char-acteristics which provided verification to theconcept of the J7W.

For further testing, one of the three gliders

was modified by having a small engineinstalled in the rear of the fuselage in thesame pusher configuration as the proposedJ7W. The engine, a Nihon Hainenki Semi 11

([Ha-901 1l), allowed the handling underpower to be studied as opposed to unpow-ered flight only. Following the conclusion ofthe testing of both the unpowered and porv-

ered MXY6, the validation of the canarddesign provided the needed proof of conceptand as such the IJN instructed Kyushu to pro-ceed with the J7W Shinden.

Kugisho MXYG - data

Contemporaries

Hamburger Ha l4l-0 (Germany), FGP 227 (Oermany), Goppingen Gti 9

(Germany), Horton Ho IllB and Ho lV (Germany), Berlin B 9 (Cermanv),

Junkers Ju 49 (Germany), Lippisch DM- I (Gemany), DFS I 94 (German])

Proofof Concept Glider

One

Powerplant Unpowered except lot one modified rvith a Nihon

Hainenki Semi I I ([Ha-90] i l) 4'cylinder, air-cooled engine developing

22hp and driving a two-bladed, flred stroke wooden propeller

Type

Crew

Dimensions

Span

Length

Height

Wing area

ll,l2m

9,63m

4.20m

20.49m'

36.sft

31.6ft

13.8ft

220,6fr'

Weights

l.oaded 640kg 1,410 lb

Perfornance

Mar glide speed

The profile shown is based on one of the MXY6gliders found at Atsugi in September 1945.The paint is training orange as normally usedon experimental and training aircraft,

Deployment

None, The N'IXY6 was purely a proof0fconcept glider

zooF

o

zzo

IupeRrer- Jap,qNEss Nnvv 69

The Oka Model I I depicted here uses markingscommonly seen on deployed aircraft.

Oka Model ll - data

Special Attacker

0ne

Powerplant Three Tlpe 4 Mark I Model 20 solid fuel rockets,

each developing 267kg (588 lb) of thru$, for a total of 80lkg (1,764|b)

Kugisho M)ff7 Oka

'No longer can we hope to sink the numeri-cally superior enemy carriers through ordi-nary attack methods. I urge the use of specialattack units to crash dive their aircraft and I

ask to be placed in command of them.'These words by IJN Captain Eiichiro Jyo,

commander of the carrier Chiyoda, reflecteda mood he had observed in some of his pilotsand men. Their feelings were that to carry onwith conventional tactics was doomed to fail-ure. While death in combat was worthy, adeath that did no good was shameful andwould not serve the Emperor or Japan. Jyo'swords, written in a memo to Rear AdmiralSoemu Obayashi and Vice Admiral JisaburoOzawa, would be the catalyst for the forma-tion of special attack units and from this anew weapon would arise that would becomethe only purpose-built special attack aircraftto see operational combat service duringWorld War 2: the Krlgisho MXYT Oka.

Vice Admiral Takijiro Onishi is most oftencredited with officially forming and organis-ing the special attack units, the first of whichbecame operational in October 1944. A piv-

otal man in the formation of the IJN's

Rikusentai (airbome troops), Onishi was also

eccentric which did not always endear him tohis superiors and so, prior to his assuming

command of the IJN land air forces in the

Philippines, he served as a supply officer.Speaking to the officers of the 201stAir Group,

Onishi stated that because of the limitedresources only a Mitsubishi A6M Reisen witha 250k9 (551 lb) bomb that was crashed intoenemy ships would suffice in slowing the US

fleet. From this began the rise of the IJN spe-cial attack force, the Shimpu Tokubetsu

Kdgekitai. Their story, as well as that of theIJA's Shimbu Tokubetsu Kdgekitai, is beyondthe scope of this book (however, for thoseinterested there is a wealth of material avail-able on the subject such as David Brown'sKamikaze and Earl Rice's Komikazes).

The majority of the shimpu missions wereflovrm using types already in service. In addi-tion to the Reisen, the Kugish6 D4Y Suisei(meaning 'Comet'but known to the Allies as

Judy),Kawasaki Ki48 (l/y), Nakaiima Ki-49

Donryu (meaning 'Storm Dragon'but calledHelen by the Allies), Aichi D3A (Va1) andmany others were modified, sometimesheavily, and used against the Allies, but nonewere specifically built from the ground up forshimprl (suicide) operations. It would be IJN

Ensign Mitsuo Ota, a transport pilot flying withthe 405th Kdkr.rtai, who put forward a designfor a piloted glide bomb.

Ota's concept was not the only one thatcalled for a dedicated shimpu aircraft. Otherideas were considered such as the ShowaToka (see elsewhere in this book on theNakajima Ki-l15 Tsurugi for more informa-tion), but what set Ota's idea apart was thathe wanted to have the explosive payload car-ried internally as opposed to fitting an exter-nal bomb. Also, the aircraft had to be carriedand released by a parent plane and rocketboosters would be used to speed theapproach and terminal dive onto the target.

Ota did not have any aeronautical engineer-ing experience and would not have been ableto present a definitive plan for his aircraft. Inorder to help his cause, Ota sought andreceived assistance from the Aeronautical

ZoO

oz6

Type

Crew

Dinensions

Span

Length

Height

Wing area

Wing loading

Power loading

5l2m

6.06m

Ll5m

5,99m'

356.90kg/m'

2.67kg,/t'p

I 6,8ft

l9.gft

3.8ft

64.sfr'

73.1 lblt5,9lb,t'p

Weights

Empty

Loaded

Useful load

440kg

2,140.5k9

65Okg

970rb

4,il8tb

l,433lb

Perfornance

Max speed

Dive speed

Cruise speed

Max nnge

Ceiling

649kn/h

at 3,505m

927km,h

462krl/it

at 3,500m

37km

8,250m

403mph

at 11,500ft.

576mph

287mph

at ll,482ft

23 miles

27,066ft

Armament

1,200k9 (2,646Ib) Tri-Nitroaminol explosive warhead

Z0 JepnxEse SEcnrr Pno;Ecrs: ExpsRrN4sNreL ArRcRepr oF rHE IJA nruo IJN 1939-1945

Research Institute of the University of Tokyo.Professor Taichiro Ogawa headed the studyof Ota's conceptwhile Hidemasa Kimurapro-vided the basic design ofthe aircraft and evenproduced models that were wind tunneltested. Within weeks, the proposal for Ota'sdesign was drafted, the design illustratedand performance estimates presented alongwith the data obtained from the wind tunneltesting.

In August 1 944, Ota brought his proposal tothe attention of Lieutenant CommanderTadanao Miki. Miki was the department headof the aircraft design section of the Dai-lchiKaigun K6ku Gijutsu-sho. lt is said that whenMiki reviewed Ota's concept he was takenaback and shocked at the idea of putting meninto piloted bombs. However, by this time thepolicy of shimprl tactics had been approvedand regardless of how Miki felt personally hecould not deny the submission. Miki placedthe design before the Naval General Staff on 5August 1944. Air Staff Officer Minuro Genda,after looking over Ota's plan, approved theconcept and instructed chief of staff AdmiralKoshiro Oikawa to set the wheels in motionfor turning the design into reality. Perhaps itwas ironic that the task of starting the devel-opment of the aircraft fell to Miki. Kugishowas the organisation that would develop theaircraft, which was given the initial designa-tion MXY7. Miki assembled a team of engi-neers led by three men, Masao Yamana,Tadanao Mitsugi and Rokuro Hattori, and theybegan drafting and refining the MXYT design.

The MXYT was essentially a glider bombwith a pilot providing the guidance. Therewere several specific factors involved in theMXY7, most of whichwere out of necessity. Inorder to conserve war materials, the MXYZ

was to be constructed using wood as well as

non-critical metals such as aluminium, if nec-essary. It was expected that pilots with mini-mal skill would be required to fly the machineand therefore the aircraft had to possess goodhandling and manoeuvrability to ensure asuccessful strike. Not surprisingly, instrumen-tation for the MXYT was kept to the bare min-imum. The aircraft also had to be simple toconstruct so as to allow rapid mass produc-tion by semi-skilled and unskilled labour.

The MXYT's primary mission was anti-ship.The flight profile began with the MXYT beingcarried aloft by a modified Mitsubishi G4M

bomber. At the point where it was withinrange of the target, the G4M would releasethe MXYZ which would then glide towardsthe intended victim. During the approach thepilot would ignite the rocket motors in therear of the plane to increase its speed andclose in to the target as quickly as possible.This would minimise the chances of inter-

Il,IprRIal, JnparvEse Nlvv

ception and present a fast moving target todefending anti-aircraft gunners.

Miki and his team completed the design ofthe MXYZ in weeks and by the end of Sep-

tember 1944 ten MXYT had been completedand were ready for testing. The aircraft wasthen renamed the Oka Model I l, Oka mean-ing 'Cherry Blossom'. A 1,200kg (2,6461b)

explosive charge was fitted into the nose andfive fuses were installed, one in the nose andthe remaining four on the rear plate of thecharge. The fuses were armed by the pilotfrom inside the cockpit and they could be set

to explode on impact or the detonation couldbe delayed by up to 1.5 seconds to allow theOka to penetrate the target (such as a shiphull) and explode inside. The carrier for theOka was the Mitsubishi G4M, known to theAllies as Beffy. A number of G4M2a Model 24B

and 24C bombers were modified by havingtheir bomb bay doors removed to be replacedby the required shackles to hold the Oka.

These modified carriers were redesignatedG4M2e Model 24J. However, the Oka's loadedweight of 2,140kg (4,718Ib) far exceeded thebomber's standard load of 1,000kg (2,205 lb)and as a consequence the G4M2e sufferedfrom poor handling and performance.

As the Oka did not take-off on its own norwas it anticipated that it would fly at speedsunder 322kmlh (200mph), the wings werekept very short. For propulsion, three Type 4Mark I Model 20 solid fuel rockets wereinstalled in the tail of the fuselage. Eachrocket could produce up to 267k9 (588Ib) ofthrust for a total of 801kg (1,764Ib). The pilotcould activate them as he saw fit and couldfire them one by one or all three at once. Totalburn time for each rocket was 8-10 seconds.Given that the Oka would have to fly throughsignificant anti-aircraft fire as it approachedits target as well as the possible aerial inter-ception by Allied fighter cover, the pilot wasafforded protection through armour plate. A19mm strip of plating was fitted along theunderside of the fuselage near to the pilot'sfeet while his bucket seat had between 8mmand 15mm of armour, the majority protectinghis back.

As discussed above, the instrumentationwas kept to a minimum. The instrumentpanel contained the altimeter, compass, atti-tude indicator (artificial horizon), airspeedindicator, arming handle for the fuses and therocket motor ignition switches.

With the ten available MXYT prototypes,

flight testing was to commence in October1944. However, the IJN did not want to waitfor the results of the tests and in September,Rear Admiral Jiro Saba, director of theKrigisho Naval Aeronautical Research Labo-ratory, went to Lieutenant CommanderYokei

Oka Model 2l - data

Special Attacker

0ne

Powerplant Three Tlpe 4 I'lark I l'lodel 20 solid luel rockets,

each developing 267k9 (588Ib) oflhrust, for a total of80lkg (1,764Ib)

Type

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading

Polver loadrng

4.llm l3.5lt

6.88m 22.6ft

l.l2m 3.7ft

3.99m' 43ft:

399.78kg/m' 8l.glbift'

l.99kg/hp 4.41b,t'p

Weights

Empt".v

Loaded

Usefui load

535kg

l,60Okg

9lsks

I,l 79 lb

3,527Ib

2.01 7 lb

Performance

N'lar speed

Cruise speed

[,lax range

Ceiling

642kmih 399mph

at4,000m al l3,l25ft

413kryh 275mph

at 4,000m at l3,l25ft

I llkm 69 miles

8,500kg 27,8871t

600kg (1.322 lb) explosive rvarhead

Oka Model 22 - data

Type

Crew

Special Attacker

0ne

Powerplant

One Tsu-1 I therrnojet developinq 200ke (440 lb) of thrust

Dimensions

Span

Length

Height

Wing area

Wing loading

Power loading

4,llm i3.5fl

6.88m 22.6f1

Ll2m 3.71t

3.99m' 43ft'

401.82k9m' 82.3lbiit:

7,98ks/hp l7.6lbihp

Weights

EmpLv

Loaded

IJsehrl load

545kg 1.201 lb

l,450kg 3,1971b

965kg 2,1271b

Performance

I'lar speed

Cruise speed

IIar range

Ceiling

Fuel capacitl

Oil capacit-v

445knlrh 276mph

at 4.000m at l3,l25ft

427knyh 265mph

at3,500m at ll,482ft

l60km 99 miles

8,i00m 27,887ft

290 litres 76.6 gailons

l0 litres 2.6 gallons

71

600kq 0,322 lb) explosh'e rvarhead

Type

Crew

Oka Model 33 - data

Special Attacker

0ne

Powerplant

One Ne 20 arial-florv turbolet developing 475kg (1,047 lb) of thrust or

one Ne I28 jet eneine developing 320k9 (705lb) oilhrust

I\,latsurra at the Munitions Ministry to sort outthe arrangements for opening production ofthe Oka. Matsurra, who shared a similar dis-taste of the suicide concept to Miki, saw to itthat much of the production was handled bymilitary contractors to maintain secrecy andnot by the private aviation industry. As such,Krigishd would build the Oka at Dai-lchi Kai-gun K6kir Gijutsu-sho as well as at Dai-lchiKaigun Kokusho, and two sub-contractors,Nippon Hikoki K.K. in Yokohama and FujiHikdki K.K. in Kanegawa, would provide wingand tail assemblies. It was expected that 100

Oka aircraft would be ready by November1944.

The first unpowered flight tests of the Okabegan at the Sagami fusenal located inSagamihara in Kanagawa Prefecture. To

begin with, unmanned, unpowered flightswere conducted to assess the Oka's flightcharacteristics and these were followed soonafterwards by unmanned, powered flighttests. All of the Oka drops were made fromthe C4M2e bombers with the Okas beingdirected out into Sagami Bay. Flight testingwas then moved to Kashimi in Saga Prefec-ture which was near the IJN base in Sasebo inNagasaki Prefecture. At Kashimi, the firstmanned flight of an Oka took place on 31

October 1944 with Lieutenant KazutoshiNagano (other sources have his last name as

Nagoro) at the controls. The particular Okathat Nagano was to fly was the prototype forthe Oka K-1 trainer. In place of the warheadand the three rocket motors were tanks hold-ing water as ballast that simulated the com-bat weight of the Oka. Since there was noroom for a conventional landing gear, a cen-tral landing skid was fitted to the underside ofthe fuselage and under each wing tip wererounded skids to protect the wings and pre-

vent them from digging into the ground onlanding. Prior to landing, the water was to bejettisoned which slowed the landing speed to223knt/h (138mph). For Nagano's flight, arocket booster was fitted to the underside ofeach wing. At 3,505m (11,500ft) Nagano wasreleased from the G4M2e bomber andentered a good, stable glide. A few minutesinto the flight, Nagano activated the boosterrockets and almost immediately the Okabegan to yaw. Nagano quickly jettisoned therockets and the problem disappeared. The

remainder of the flight went perfectly,Nagano bringing the Oka down withoutmishap after releasing the water ballast. Sub-

sequent investigation showed that uneventhrust from the rockets caused the yawingand Nagano is said to have stated that the Okahandled better than a Reisen.

As flight testing and production of the Okagot underway, 721st Kokutai was formed at

Hyakurigahara Airfield on 1 October 1944

under the command of Commander Moto-haru Okamura with Lieutenant CommanderGoro Nonaka and Lieutenant CommanderKunihiro Iwaki as his operations officers. Theunit was nicknamed the Jinrai Butai, translat-ing as 'Thunder God Corps'. Through Octoberthe unit received hundreds of volunteers.Those who were too old, married or wereonly sons, or those with significant familyresponsibilities, were rejected for the JinraiButai, leaving 600 pilots to be accepted intothe unit. The 721st Kikotai consisted of the708th Hikotai and the 711th Hikotai, eachwith18 G4M2e bombers. The 306th Hikotai andthe 308th Hikotai were assigned the task ofescorting the Oka carrying bombers, eachsquadron maintaining 36 Mitsubishi A6MReisen fighters. The unit's initial l0 Oka air-craft were supplemented by some 40 Mit-subishi A6M5 Reisens fitted with 250kg(551lb) bombs.

Flight testing of the Oka continued through-out November. These tests showed thatwhen dropped from 5,944m (19,500ft) at a

downward glide angle of 5.5' the Oka couldachieve a range of 60km (37 miles) at a speedof 317km/h (230mph). In anearlyvertical diveit was clocked at over 966km/h (600mph).

However, under combat conditions the Okacould manage 25 to 29km (15 to 18 miles).Based on the tests and flight experience, amission profile was developed for the Oka'sdeployment. Flying at a height between6,096m and 8,230m (20,000f1 and 27,000f1),

the G4M2e would release the Oka when itwas within 1 7 to 33km (10 to 20 miles) of thetarget. The pilot would then enter a shallowglide with an airspeed of between 371km/hand 45lkm/h (230mph and 280mph). At apoint about 8 to 12km (5 to 7 miles) from thetarget, and from an altitude of approximately3,505m (l 1 ,500ft), the pilot would activate therocket boosters increasing the speed to649km/h (403mph). Prior to striking the tar-get, he would put the Oka into a 50'dive thatwould take the speed up to nearly 934km/h(580mph). At the last moment, the pilotwould pull up the nose to strike the ship at thewaterline.

Oka pilot training was soon underway. Typ-ically, the pilotwould use a Reisen to practicethe Oka attack routine flying the fighter withthe engine switched off. For many, they onlyhad the opportunity to become familiar withthe Oka while it sat on the ground. A few werefortunate to make an unpowered flight usingone of the MXYT trainer prototypes. As

expected, accidents occurred and on 13

November 1944, the Oka claimed its firstcasualty. Lieutenant Tsutomu Kariya exe-cuted a perfect drop from 2,987m (9,800ft)

Dimensions

Span

Length

Height

Wing area

Wing loading

Power loading

4.99m

i.l9m

1.15m

5.99m'

382.78k9/m:

4.76kgtrp

16,4fr

23.6ft

3.8fr

64,5fr'

78,4lb/fr,

I 0.5 lbi/t'p

Weights

Empty

Loaded

Usefui load

N/A

2,300k9

N/A

Performance

Max speed

(Ne20)

Cruise speed

\'lar range

Ceiling

Fue) capacity

0il capacity

643knl/tt

at 4,000m

N/A

2l2km

N/A

250 litres

N/A

399mph

at 13,1251t

132 miles

66 gallons

Armamenl

800kg (1,763 lb) explosive warhead

Oka Model 43A- data (estimated)

Special Attacker

0ne

Powerplant

One Ne 20 axialflow turbojet developing 475kg (1,047Ib) oi thrust

Type

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading

Power loading

8.99m 29,5ft

8.16m 26.8ft

1.12m 3.7ft

12.99m: l39.9lt'

193.83kg/mr 39,ilb/it'

5.30k9hp l1,7lb/hp

Weights

Empty

Loaded

Useful load

N/A

2,520k9 5,5551b

N/A

Performance

Mar speed

Cruise speed

Nlax range

Ceiling

Fuel capacitv

0il capacity

596km/h 370mph

at4,000m at l3,l25ft

N/A

200km l24miles

N/A

400 litres 105.6 gallons

16 litres 4,2 gallons

Armament

800kg (1,763Ib) explosive warhead

72 JlpnruEsn SecnEr PnoJscrs: ExpsRIN4ENraL AIRcnapr oF rHE IJA AND IJN 1939-1945

:-

!zzc

and was bringing the Oka down for a landing.He inadvertently released the water ballastfrom the nose tank, leaving the rear tank full.This immediately caused the nose to pitchup, putting the Oka into a stall that Kariya wasunable to recover from, the plane crashinginto the ground. Kariya was pulled from thewreckage but within a few hours had diedfrom his injuries.

By December 1944, Ktgisho had produced151 Okas and the Dai-lchi Kaigun Kokushoproduction was also well under way.Attempts were made to deploy the Oka lounits outside of the Japanese home islands.Fifty were dispatched to the Philippinesaboard the carrier Shinono, but on 29 Novem-ber 1944 the ship was sunk en route. Only ahandful would reach other bases, notably inOkinawa and Singapore, and none would see

combat. Even though the 721st had yet to see

combat, there were some who realised thatthe G4M2e bomber would be easy targets forenemy fighters and the odds of actuallyreaching the target were small. Conse-quently, morale dropped as the Oka was seenas a waste of a pilot who could be used to bet-ter effect elsewhere. The vulnerability of theG4M2e was vividly displayed when the 721stwent into battle for the first time on 2l March1945. Attacking US Task Group 58.1, all 18

bombers (of which 15 were Oka carriers)were shot out of the sky by US Nar,y fightersalong with their fighter escort before theycould getwithin attack range. Again, the storyof this and subsequent Oka missions arebeyond the scope of this book but the inter-ested reader can find many excellent sourcesof information on the topic.

Inrpenral JepeNesE Navv

Following the Oka's disastrous debut,reviews of gun camera footage from the US

Navy fighters and from pilot debriefingsrevealed the existence of the newweapon forthe first time to the Allies. At first it wasthought that the Oka was simply a large, anti-ship bomb. This would change when four tosix examples were captured near KadenaAir-field after the Allied victory at Okinawa. Onlythen was the aircraft's true nature madeknown to Allied intelligence. The Oka wassubsequently given the codename Baha bythe Allies, the word baka meaning 'fool' inJapanese.

Production of the Oka Model l1 ceased inMarch 1945 with the Dai-lchi Kaigun KdklGijutsu-sho having built 155 and the Dai-lchiKaigun Kokusho constructed a total of 600.

One Oka Model 11 was fitted with sheet steelwings made by Nakajima but no other exam-ples were produced with this feature. To helpimprove the training regimen, once the Dai-

Ichi Kaigun Koku Gijutsu-sho had completedtheir run Oka production was switched to theOka MXYZ K-1 trainer. In all, 45 of the K-lwould be completed and placed into the pilottraining program.

Clearly, the G4M2e carrier aircraft was tooslow and easy prey for defending Alliedfighter protection. In addition, the short rangeof the Oka Model 1l compounded the prob-lem. Consequently, Krlgisho decided to utilisethe superior Klgisho P1Y Ginga (Allied code-name Fronces) as the carrier aircraft and alsoto give the Oka a longer range. This adapta-tion was called the Oka Model 22.

The primary change in the Oka Model 22

was the use of the Tsu-11 thermojet engine in

Oka Model 22 in the colours of the example foundat the close of the war and now on display at theSmithsonian Air and Space Museum.

Oka Model 43B - data (estimated)

T1pe SpecialAttacker

Crew One

Pow€rplant One Ne20 axial-flon turbojel developing 175kg

(1,047Ib) olthrust: one Tlpe I tr'lark I \'lodel 20 solid luel rocket.

deleloping 256kg (565Ib) of thrust

Dimensions

Span

Length

Height

Wing area

Wing loading

Pouerloading

8.99m 29.5f1

8.16m 26.8fi

1,12m 3.7ft

12.99m: 139.9ftr

l74.79kgim, 35.8lbrfr

5.18kgihp 12.1 lbihp

Weights

Emptl

Loaded

Useful load

i,l50kg

2,270kg

I,l20kg

2.535tb

5.0011b

2,4691b

Performance

llar speed

Cruise speed

i\'lax range

Ceiling

Fuel capacitl

0il capacitl

556kmih

at 4,000m

NlA

277km

300 litres

16 litrcs

315mph

at l3.l25it

172 miles

79.2 gallons

4.2 gallons

Armament

800kg (1,763 lb) explosir,e narhead

l,)

Type

Crew

Oka Model 53 - data (estimated)

Special Attacket

One (or none)

Powerplant

One Ne20 arial-florv turbojei developing 475kg (1,047Ib) ofthrust; one

Trpe 4 \'lark I solid iuel rocket, developing 267kg (;88lb) 0f thrust

place of the rocket boosters. This consisted ofa 100hp Hitachi Hatsukaze [Ha-I1-11] l1 4-

cylinder, inverted inline engine driving a sin-gle-stage compressor. Fuel was injected intothe compressed air that was then ignited, pro-ducing up to 200kg (440 lb) of thrust. To com-pensate for the weight of the engine and fuel,

the warhead had to be reduced to 600kg(l,323 lb). Finally, as the PlYwas smaller thanthe G4M2e, it was necessary to reduce thewing span by lm (3.2ft), although the lengthof the Oka Model 22 was increased by .8m(2.6ft). These changes improved its range ofup to 129km (80 miles), although 65km (40

miles) or less was considered achievableunder combat conditions. A rocket boostercould be fitted to the underside of the fuse-lage to increase speed during the terminaldive.

Once the design of the Oka Model 22 wasfinalised, Ktgisho began a production run of50 aircraft even before flight testing wasunderway. Aichi Kokuki K.K. was contractedto construct a further 200 Model 22 aircraft,but due to US B-29 bomber raids Aichi's pro-duction lines would never enter operation.Once the first handful of Oka Model 22 aircrafthad been made available their testing began.Thanks to its short wings, a high siall speed of334kmih (207mph) and high landing speedmade a soft landing impossible. Test pilotswere instructed to abandon the Oka ratherthan make a landing. Lieutenant KazutoshiNagano took the Oka Model 22upfor the first

time on 26 June 1945. The flight would also behis last. After being released from a modifiedKugisho PlYl at 3,658m (12,000ft), the Okawent out of control (another source states

that the wing rocket boosters fired acciden-tally, causing the Oka to crash into the Ginga,

damaging the Oka's controls). With no abilityto regain level flight from the plummetingOka, Nagano was able to extract himself fromthe stricken aircraft but his parachute onlypartially opened before he hit the ground andwas killed. A second test model was ready inAugust 1945 but the war ended before it couldfly. Although fifty Oka Model 22s were built,the carrier, the Kr-rgishd P1Y3 Model 33, wouldnever leave the drawing board. The com-pleted Oka Model 22 were retained in Japan

for use against the expected Allied invasionforce.

K0gishO continued to investigate ways toimprove the performance of the Oka and a

series of models were planned around the

KugishO Ne 20 turbojet. The first was the OkaModel 33 which was simply the Oka Model 22

enlarged to accept the Ne20 (or as one

source states using the Ne12B.iet engines

that had been built prior to the shift to theNe20 development). For a carrier, Kugisho

planned on using the Nakajima G8M1 Renzan(known as RrTa to the Allies) but with the fail-

ure of the Renzan to enter production, theOka Model 33 was quickly shelved withoutany prototype being constructed. This wasfollowed by the Oka Model 43A. Larger indimensions in comparison to the Oka Model22, rhe Oka Model 43A was designed to belaunched from submarines such as the Sen

Toku class. To facilitate storage on such boatsthe wings were foldable, but with the Allies incomplete control of the seas the oka Model43A was soon put aside and work begun onthe oka Model 43B instead.

This version was designed to operate fromcaves and launched by a catapult. It retainedthe folding wings to allow the productionlines to be set up in cramped, undergroundsites or caves as well. Unlike the previousmodels, the oka Model 43B was all metal,used a central skid and in order to better facil-itate target penetration the pilot could iettisonthe wing tips. Like the Oka Model 22, a rocketbooster could be carried under the fuselage.A full scale wooden mock-up was completedin June 1945 and was promptly approved forproduction. Aichi were tasked with construc-tion of the Oka Model 43B at their Gifu and

Oyaki factories but the war ended before thefirst prototype was completed. However, a

catapult ramp was built at Takeyama, nearYokohama, and pilots destined for the OkaModel 43B were being given instructions oncatapult launching as theywaited for their air-craft to be delivered.

A hybrid Oka was considered which wascalled the Oka Model 2 1 . The Tsu- 1 I enginewas to be removed from the Oka Model 22 tobe replaced by the standard rocket boostersystem as used on the Oka Model ll. Thismay have been contemplated as productionof the Tsu-l1 engine was slow and was notkeeping pace with the Oka Model 22. Theproposal, however, never proceeded past asingle prototype.

Whereas all previous Okas, with the excep-tion of the Models 43A and 43B, requiredmodified bombers to carry them aloft and

launch, the Ne 20 turbojet equipped OkaModel 53 was designed to be towed into the

air. As such any aircraft, with the addition of a

tow line and having enough power, could be

used to tow the Oka Model 53 into the air.Nothing came of this design due to the end ofthe war. However, it is worth noting that somecontemporary illustrations show the OkaModel 53 without a cockpit, which would turnthe type into a glider bomb. For guidance, it is

speculated that upon release from the towaircraft, it was either radio controlled from aparent plane or used infrared or acoustichoming to guide itself to the target. This con-

Dirnensions

Span

Length

Height

Wing area

Winq loadins

Porver Ioading

6.43m

7.77m

1.43m

8,99m'

N/A

N/A

21,lft

25.5fr

4.7ft

96.8fr,

Weights

Empty

Loaded

Useful load

N/A

NlA

N/A

Performance

N'lar speed

Cruise speed

l,la\ range

Ceiling

Fuel capacitt

Oil capacitv

NlA

N/A

277km

N1A

400 litres

l6 litres

172 miles

105.6 gallons

4.2 gallons

Amament

600ke (1.322lb) erplosire warhead

Oka K-l - data

Type

Crew

Trainer

0ne

Powerplant

Dimensions

Span

Length

Height

Wing area

5.12m

6.06m

l,l2m

6,00m'

l6.8ft

19.9ft

3.7fr

64,6fr

Weights

EmpI

Loaded

Uselul load

730k9

2,l20kg

l50kg

1,6091b

1,673tb

330Ib

Performance

['lar speed

Cruise speed

Landing speed

N/A

l47krilh

200k'ri,"h

9imph

l24mph

T4 JepnNssE SscnEr PRo;Ecrs: ExpeRrn'rEnral ArncRnnr oF THE IJA AND IJN 1939-1945

cept has not been verified in rvartime Japan-ese sources and could be post-rvar conjec-ture.

A derivative of the MXYT K-1 rvas plannedand this rvas known as the Oka Modcl 43 K-lKai Wakazakura (meaning 'Young Cherry' in.lapanese). This was to be the definitiveIr';rinel lol pilots destined for operalional Okamodels. A second cockpit r'vas installed in thenose in place of the warhead, flaps were fit-ted to the rvings to help with landing and, likethe K-l, the Nlodel 43 had a central landingskid with wing bumpers. It also included asingle Type 4 Mark I Model 20 rockct in thetail to allorv the student to get a taste ofporvered flight. By the close of the r.var onlytrvo of the Wakazakura trainers had beencompleted.

Perhaps one of the more unusual uses forthe Oka occurred in Singapore. The handfulof oka Model I 1 aircraft that were received byunits in Singapore rvere, for the most part,groi,rnded because they did not not have thcir

G4M2e parent aircraft. In order to get someuse from the Okas, mcchanics planned to fitthem lvith floats cannibalised from unser-viceable or available floatplanes such as theAichi E13A (hnown as Joke to the Allies). It isnot knorvn exactly horv the lloats r,vere to beinstalled but crudc fittings could have beenfabricated to attach a float under each ,"ving.

It is belicrcd that lhe float cquipped Okaswere to be positioned along the Straits ofJohor that separate Johor from Singapore andbe used in conjunction ',vith Shinyo specialattack boats. Another unknor,vn is holv theylvould have performed given the short burntime of thc rocket boosters let alone handlingqualities across watcr. It can be surmised thatperformance rvould have been very poor. Bycomparison, thc German Tornado attackboat used two floats fi-om a JunkersJu 52l3mg5e and rvas pon'ered by an Argus109-014 pulse-jet. Trials rvould prove a failureas the boat could not operate on anything butcalm seas rr illroul cap5isinq.

Oka +3 K-l Kai - data

Ttpe

Cren

Trainel

Ino

Ponerplant

0ne Tvpc 1 \lark 1 -solld hrel r0cket. de\elopinq 26llq (ritjlb) ollhm,'l

Dirnensions

Span

L.enqth

Heiqht

\\ inq iirea

i.l2rn

6.0lin

Ll2nr

!A

16.8fr

19.ltil

I ift

iVeights

lnrplr

Loaded

I setul load

ll+kq

El{)kg

llilkg

t,.lt 1l lb

t,i.q; lb

i{ii llr

Performance

\l:u -pce d

Cruisc spccd

Landirr! spcd

!Al2llkm h

\,A

E0mph

fumament \one

l'.itl'.'.

Iuprrir,ql JaparEsn Nlvy 75

E=Jdz-

Oka Model 43 K-l Kai

shown in the

standard orange huefor training andexperimental aircraft.

K-l Ktgisho MXYT Oka - data

Contemporaries Daimler-Benz Projekt E and Prolekt F (Germany),

Messerschmitt N{e 328C (0ermanl)

Deplolrnent

\raried. The oka I'lodel I I and NIX\'7 K"l san'operational seruice. The

Oka \lodel 22 u as deplor ed bul did not .ee acriOn. Ihe oka luodel 2 I

remained a single protot\De. The oka I'lodel 138 protot\pe uas incom-

plete at rvar's end. The oka N'lodel 33, 43A and 53 remained designs

0nh" The oka ['10del 43 K-l Kai $'as too late to be issued to training

units.

Survivors

Kugisho MXYT oka (FE-N50)

The 'N' is assumed to signifr 'Nalr' as in the US Narr'. therebv denoting

the LrS Narryu'as evaluating this parliculal aircraft. This MXYT was listed

on a l0 l'larch 10 1946 repofi allou'ing il to be released t0 a\iation indus-

try. 0n 1 August 1 I 916, an inventorr reported it at \'lA['1A and bv I 8 Sep-

tember i916 \\'as slated lor lhe museum and storage at Park Ridge. No

further trace ofthe [JXY7 is kno$n.

K0gisho oka \'lode1 I I (no tail number assigned)

One of a number oiOka aircrait taken t0 lhe US, this one, serial number

1019, was obtained bI Ed$ ard \'lahonev. li $as restored and remains on

displav at his Planes ol Fame Museum in Valle, Arizona.

Kngisho oka Model I 1

Bearing the serial 1018, this oka is currenth'on displa| at the l'larine

Corp. Barp qron1 , o. near I rianqle. \'irqinia.

Kugisho oka N'lodel I 1

Originallv this okawas in the collection oithe \iictoryAjr l'luseum ]Ocated

in l\'lundelern, Illinors. It closed ils doors in 1984 and the aircraft lvas sold

off, It ruas lasl obtained by the Yanks Air I'luseum in Chino, Calilornia.

K[gish6 oka ]\'lodel 1 I

Shipped to India in September 1947 bt'the No,4 Squadron of the Indian

Arr Force lollou'ing their duties in Japan as pa( of the British Common-

nealth Occupation Forces, the Oka is cunentlv on display in the Indian

Air Force Museum at Palam Air Force Station, Nen Delhi, India.

K[gisho oka \'lodel I I

Another Oka in England, this time drsplaled at the FleetAirArm

Museum in Yeorilton. Somersel, LK.

Kngisho oka Model I 1

This example olthe oka is in the collection ofthe tr'luseum ofScience

and industry in \'lanchester, UK, $'ith the registration number ol

11996.53.10. Since 1961, this Oka has passed through a number olmuse

ums beiore ii reached its currenl lOcatiOn.

Kugisho oka tr'lodel I I

This oka is housed in the collection 0f the Deience Lrplosive Ordnance

Disposal School. The school is cunentll located in Chattenden, Kent, but

is to be relocated t0 St. George's Barracks, Bicester in Oxfordshire, UK.

K[gish0 oka Model I I

The lourih oka in the British Isles is on display at the Rolal Air Force

\luseum at Cosiord in Shropshire. Prior to this, it uas housed at the

Rocket Propulsion Establishment in\\restcott, Buckinghamshire.

Kugisho oka Model I I

This, the onl,-v knom genuine oka in Japan (a replica is used at the

Yasukuni Shrine in Chiroda. Tokroar nell a. lhe Okd Paik in Ka.hima

Citr, Ibaraki Prefecture), is currently housed at ImmaAir Base, a Japan-

ese Air Self.Deience Force facilit.v in lruma, Saitama Prefecture. During

the \4ar it rvas at the IJA base IrumagarvaAirfield,

Kugisho oka l\'lodel 22

Restored and on displa,r'at the Smithsonian Air and Space l,luseum.

K[gisho I'IXY7 K-l

\Vith a serial number of 5100, the \lXY7 K-l is housed in the Nary

l'luseum at the Washington Naly Yard in Washington, D.C.

Kugish6 MXYT K-l

This lrainer is cunenth on display at the National N'luseum of lhe United

Siates Air Force, located on the proped\' 0f the WrighlPattersonAir

Force Base in Riverside, Ohio, which is just outside 0fDavton. Ohio. At

one Iime itha. pdinted a' an operalional Oka but ha" rince been

retumed t0 the orange colour scheme ofa trainer,

Kogisho oka l\,lodel {3 K-1 Kai

At present. this trainer bearing the serial number 6l is in st0rage and

unrestored at the Paul E. Garber facility.

(Noie: The Kugish0 oka \'lodel I I displa.ved at the Wings ofEagles

museum in Horseheads, NY, is a replica,)

76 Japallrse SEcnnr PRoJECTS: Explnlr'tEnraL AIRcRntr oF rHE IJA AND IJN 1939-1945

The design and development ol the Mitsubishi

J8Ml Syusui presented a challenge. Despite the

information available to the Japanese on theMesserschmitt Me 1638, upon which the J8M1

was based, the concept of a tailless fighter, let

alone a rocket powered one, was new and

untested. What was required was a means toverify the design of the J8M1 and in doing so

provide a way to train pilots who would be fly-

ing a plane that was unlike any they had everflown before.

Therefore, Kugishd was given the task of cre-

ating a glider that was to be a copy of the J8Ml.The main purpose was to assess the flight char-acteristics of the tailless fighter given that the

Japanese did not have extensive experiencewith such aircraft. Data collected from flying

the glider would in turn be reviewed andapplied to the J8M1 fighter prior to series pro-

duction. In addition to seruing as a proof of con-cept vehicle, the glider would provide themeans to train new pilots in flying the aircraftsince it was like no other fighter then in servicein the IJN and IJA. By using the glider as a

trainer, pilots could better transition to the J8M 1

and therefore minimise operational mistakes.Krigisho assigned the glider construction,

called the MXY8 Akigusa (meaning 'AutumnGrass'), to engineer Hidemasa Kimura. Kimura

utilised wood with some cloth covered sur-

faces in the design of the MXY8 and ensuredthat the glider was a near exact replica of theJBM1 in order to provide the most accurateflight data once testing got under way. By the

close of 1944, the first MXYS was finished andanother two were nearing completion.

In December, the first MXY8 was taken to the

airfield located in Hyakurigahara, which is

about 79km (49 miles) northeast of Toky6. Itwas here that the tJN's Hyakurigahara AirGroup was stationed, operating in the defenceof Toky6. Also at the airfield was the 312th

Kokritai, a newly formed unit that was to be

equipped with the J8Ml once it entered pro-

duction. As such the 31 2th Kdkt-ttai was the per-

fect group to begin testing the MXY8. The first

tlight, scheduled for 8 December 1944, wasgiven to Commander One. Unfortunately, One

was taken ill and was unable to fly so the mis-

sion was assigned to Lieutenant-CommanderToyohiko Inuzuka. On the day of the flight,lnuzuka climbed into the cockpit of the MXYS

and once secure, a Kyrishir K1OWl of the 312th

Kdkr-rtai took the glider into the sky. At altitudeInuzuka was released from the tow plane andbegan his descent. After successfully bringing

MXYS shown in the orange colouration as used ontrainers and experimental aircraft.

InpsRraL JapnrlrsE Navv

Kugisho MXYS and MXY9

the glider down, Inuzuka gave the MXY8 high

marks, having found the handling and flight

characteristics to be very acceptable.The IJA, who were also slated to fly the J8M1

as the Ki-200, was provided with the secondMXY8. Delivered to the Rikugun KokuyijutsuKenkyujo, the pilot selected to test the MXY8 for

the IJAwas Colonel Aramaki, and like Inuzuka,

he felt that the MXY8 performed well. The onlynotable deficiency to be found by both Inuzukaand Aramaki was the tendency for the MXY8 to

nose over into a dive. The third MXY8 to be builtwas delivered to the Naval Air Force.

The first MXYS did not match the combatweisht of the J8M1. To this end the IJN wantedto modify the MXY8 so that it incorporated bal-

last tanks'nvhich could hold enough water to

fully simulate the combat weight of the J8NII

and be the definitive production model for use

in training pilots. With the completion of the ini-

tial three MXY8 gliders by Klgisho, a number ofmanufacturers were organised to begin the

production of the revised 'hear'y' MXY8 glider tomeet the training needs of the 312th Kokutaiand other units that would be flying the J8M1

and Ki-200. Maeda KOk[ Kenkyujo was tasked

with producing the MXY8 for the IJN and the

MXYS was to be built for the IJA by Yokoi Kokti

K.K. as the Ku-l3.Further flight testing by the 312th Kdklrtai

found that the MXY8 experienced aileron flutterat speeds above 295km/h (183mph) (as a side

note, the same problem was encountered inthe Messerschmitt Me 163A Vl first prototlpeduring testing). This and other minor problems

were noted, analysed and corrected, and the

flutter issue was resolved by closing the gap

between the wing and the aileron (the Me 163A

Vl was rebalanced). In the meantime, the

MXY8 was being flown by NavalAir Force pilots

at the Kashiwa airfield in Chiba Prefecture.However, the pilots were less enthusiastic on

the design, especially after a crash involving

one of the gliders that severely injured the pilot.

Regardless, the Kaigun Koku Hombu assessed

all of the data from the test flights and formally

approved the MXY8 on March 1945 and workproceeded with full production of the MXY8

and Ku-13 that continued until the end of the

Klgisho MXY8 - data

Contemporaries \lesserschmilt I{e 1635, Hcinkel He l62S (Cermanr')

Data is fot tlrc ,\lXY8. The specrficotions also applt lo the fahoi Ku'l 3.

trio specific datais at:ailable on the \IXYS Shuha,

Proof ol ConcepliTraining Glider

0ne

Potrerplant

T}?e

Crew

Dimensions

Span

Length

Height

Wing area

9.50m 31.2ft

5.82m lg.lft

2.16rn Lift

17.6im 190ft

lVeights

Emptr

Loadcd

90jkg 1,99;lb

l.037kg 2,286Ib

Performance

\lax glide speed

\'lax tou' spced

Lnknown

295knrh l83mph

Deplolment Kugisho built the thiee prolott pe MX\'8 gliden, \laeda

constructed .ll to r4 \'lX\'8 trainers rvhile Yokoi produced 6 Ku-13 train'

ers. A number of l\'1XY8 gliders wcre operated bl the 312th Koklrtai.

\0 \'l\\9 $as constructed and the pr0ject remained a design onlt.

Another version of the glider was investi-gated by the IJN. Whereas the MXY8 was

unpowered, the new version would have some

means of propulsion. Designated the MXY9

Shuka (meaning 'Autumn Fire'), the newdesign was to be an advanced trainer which,because it had the means to propel itself whenit was airborne, would provide training with amodicum of power and offer longer flight

times. It was envisioned that once training inthe MXY8 was completed, pilots would transi-

tion to the MXY9 for advanced training before

moving to the JSMl or Ki-200. The propulsion

method proposed was the Tsu-l1 thermojet.This was the same engine as used in the

Ktgisho Oka Model 22 (see Page 70). However,

the MXY9 was neverrealised.

z

77

zooI

3odzzo

Given the expanse of the Japanese empire by1942, the IJN found that they had a need for along range reconnaissance aircraft that couldoperate from land bases and fly at high speedto render it immune to interception. In thesame year, the IJN issued a 17-shi specifica-tion for just such a plane and Kugisho lookedto provide the response.

The 1942 17-shi specification called for theaircraft to have a maximum speed of667km/h (414mph) at 6,000m (19,685f1) alongwith a mission profile of long range recon-naissance. The speed requirement stemmedfrom the need to be able to avoid intercep-tion; the intelligence it gathered would beuseless if the aircraft was shot down before itcould return to base. The initial design, theRlYl Gyoun (meaning'Dawn Cloud'; othersources use Seiun, meaning 'Blue Cloud'),bore the designation Y-30 and was to bedeveloped around a new Mitsubishi, 24-cylin-der, liquid-cooled engine that was projectedto produce 2,500hp. However, delivery of theengine was not expected to be rapid and in

Kugisho R2Y Keiun

order to proceed with the RlYl, K[gishOdecided to utilise two Mitsubishi MK10Aradial engines. In so doing, the RlY1 took onthe appearance of the Kugishd P1Y1 Gingaand with the use of two radials and the result-ine drag imposed by them the RlYl's calcu-lated performance was projected to fallbelow the 17-shi specification. Consequently,all work on the RlYl ended and the projectwas abandoned.

Even as Ktgisho was working on the RlYl,they were developing another design, the Y-

40, which was the result of an evaluation ofthe Heinkel He 119, two examples being pur-chased from Germany in 1940.

The He 119 was an attempt to create a fast,

unarmed reconnaissance aircraft whose highspeed would enable it to avoid interceptionand elude pursuit. To accomplish this, theHe1l9 used radical concepts to minimisedrag and thus enhance speed performance. Apair of Daimler-Benz DB 601 engines coupledtogether drove a single propeller shaft. Theengines were placed in the rear of the He I 19

fuselage with the shaft running forward,through the middle of the cockpit, spinning afour-bladed propeller in the nose. To cool thepaired powerplants, the He 119 used a wingsurface evaporation system in which steamfrom the engines was circulated through thewings where it cooled and condensed backto liquid where it was pumped back to theengines. To cool the engines when on theground or during take-off and landing (due tothe lack of sufficient airflow across the wingsat such times), a supplementary radiator wasinstalled under the forward fuselage. TheHe 119 Vl first prototype attained a top speedof 565km/h (351mph) at 4,500m (14,765ft).

Unfortunately, Heinkel was forced intoadding armament to the He 119 but this wasdone in a very minimal fashion. The V2, witha full functional bomb bay, was able to reachspeeds of up to 585km/h (363mph) at 4,500m(14,765f1). The V4 was used as a recordbreaker, briefly holding the record for speedwith a 1,000kg (2,205Ib) payload on a closed1,000km (621 mile) circuit with the average

78 hplruEse SrcRsr Pno:Ecrs: ExpEnn'rpNraL ArRcRnnr oF THE IJA arun IJN 1939-1945

speed of 504.97km/h (313.78mph). Later theV4 was wrecked in a crash during an attemptto better that time. The record was set on 22

November I 937 and the successful aeroplanewas listed as the 'He 606'. The V3 was built as

a float-plane, intended to best the 1,000km(621 mile) seaplane speed record. Ultimately,the V5 through to the V8 would be the lastHe 119 aircraft built because the Luftwaffeshowed no further interest in the aircraft.

Following testing in the summer of 1938, adelegation from the IJN was able to inspectthe He119 at Marienehe in Germany. TheJapanese were most impressed by the rangeoffered by the He 119 as well as its speed. Ofinterest were the coupled DB601 engines.After reporting their positive findings, ninetechnicians from the Dai-lchi Kaigun KokrlGijutsu-sho flew from Japan to Germany tostudy the He 119 further. Commander HideoTsukada arranged to obtain the manufactur-ing licence for the He 119 and also the pur-chase of the He 119 V7 and V8. Both aircraftwere crated for shipment and sent to Japanarriving in May 1940. Reassembled at Kasum-igaura, Krlgishd began flight trials under theleadership of Major Shoichi Suzuki. Duringthe brief trials, one He 1 l9 was lost to landinggear failure (the He 1 19 used a special,retracting telescopic oleo leg in order for thelong landing gear to fit into the wings). In theend plans to manufacture the He 1 19 in Japandid not come to fruition.

Although the He 119 was rejected, the studyof this aircraft resulted in the development ofthe Y-40. Like the He 119, the Y-40 was to be afast, unarmed two-seat reconnaissance air-craft using coupled engines placed within thefuselage behind the cockpit and driving a pro-peller via an extension shaft. The IJN's l8-shispecifications for a long range reconnais-sance aircraft were based on the Y-40.

The Y-40 project, by now called the R2Y1

Keiun (meaning 'Beautiful Cloud'), was ledby Commander Shiro Otsuki and his designteam made good progress. The Keiun was tobe equipped with two Aichi Atsuta 30 enginescoupled together in a combination known as

the Aichi IHa-701 10. The 24-cylinder, liquid-cooled IHa-701 10 was rated at amaximum of3,400hp and drove, via the extension shaft, a6-bladed propeller. The Keiun did not use thesame method of cooling as the He1l9.Instead, it relied on air intakes and a radiatorbath underneath the fuselage, and it also dif-fered from the He 119 in that the Keiun useda tricycle landing gear system and was not atail sitter.

By the fall of 1944, the war situation forJapan was deteriorating. With the loss of terri-tory to the advancing Allies, the IJN no longersaw a need for a long range reconnaissance

Il,Ipenral JepnnEsp Navv

aircraft. Following the defeat of the Japanesein the Marianas Islands (following OperationForager), the fate of the Keiun was all butsealed. The IJN had no need for such a planeas existing designs would be adequate for thedwindling Japanese holdings. In addition, theneed for fighters and bombers was rathermore urgent than reconnaissance aircraft.

But Otsuki and KDgishO did not let theKeiun fall by the wayside. In late 1944,

Klgishd approached the IJN and informedthem that the R2Y1's airframe was readilyadaptable to other roles, including that of afast attack bomber. To heighten the interest,itwas proposed that the IHa-70] 10 engine bereplaced with two Mitsubishi Ne330 axial-flow turbojets, each of the engines beingslung under the wings in nacelles. The fuse-lage space vacated by the Aichi engine wouldbe replaced with fuel tanks. For weapons, theaircraft would carry one 1,800kg (7641b

bomb) and have a cannon armament in thenose. With the introduction of the Ne330engines, the maximum speed was expectedto be 495mph, superior to the projected720kmlh (447mph) top speed of the Aichiengine model. With these advantages inmind, the IJN approved that work shouldbegin on designing the R2Y2, the turbojetpowered Keiun which was sometimesreferred to as the Keiun-Kai, as well as per-mitting the R2Y1 to be completed as an air-frame demonstrator to test the handlingcharacteristics.

In April 1945, the first prototlpe of the R2Y1

was completed and moved to Kisarazu inChiba Prefecture to begin flight testing. Initialtaxi trials, conducted by KugishO test pilotTereoka, showed that the nose wheel had abad shimmy when in motion and the Aichiengine was prone to overheating. The latterwas either due to a lack of airflow through theradiators and inlets during taxi tests orthrough a poorly designed cooling system.Nevertheless, despite the problems testing ofthe Keiun continued.

On 8 May 1945, Lieutenalrt-CommanderKitajima, another Kr-rgisho test pilot, took theKeiun on its first flight. Kitajima noticed thatthe oil temperature was rising rapidly and he

cut short the flight, landing the Keiun beforethe engine suffered damage. Mechanics andengineers continued to try and solve the cool-ing problems, but a few days later the enginecaught fire during ground testing, completelydestroying the power unit. Then before theKeiun could be returned to Krigish6 to receivea new engine, the aircraft was destroyed by aUS bombing raid.

Even before the destruction of the firstR2Y1, a second was being constructed anddesign work for the R2Y2 was underway.

Contemporary sources show no less thanfour versions for how the R2Y2 may ultimatelyhave appeared. The first had the Ne330engines in underwing nacelles. The secondversion showed the two engines buriedwithin the fuselage with wing root air intakesand narrow jet nozzles. The third removedthe wing intakes and replaced them with anose intake, but it retained the narrow noz-zles. Finally, the fourthwas similar to the thirdsave that the engine nozzles were larger. Thefirst design is considered by most to be the ini-tial R2Y2 concept while the other three aresubject to debate. In part, this is due to thefact that the Japanese had very little time toexplore various installations of turboiets inairframes. The easiest means to place turbo-jets on aircraft was by using nacelles and thiswas seen in the Nakajima Kitsuka, NakaiimaKi-201 Karyu and proposed Klgishd Tengaand Kawanishi K-200.

Even the Germans with their turbojet expe-rience did not fully understand the effects ofa long nose intake feeding a high perfor-mance jet buried in a combat fighter's fuse-lage. Messerschmitt, when they began tostudy how to start the P.1 101 second genera-

tion jet fighter, catalogued the obstacles thatneeded to be overcome. They included theeffects of engine operation on the fuselageintegrity, ensuring the nose intake was prop-erly positioned and shaped for maximum air-flow, making sure the intake tube was madeas smooth as possible to minimise air restric-tions, how to protect the rear of the aircraftfrom the heat generated by the exhaustthrust, the effects of reduced airflow on thrustdue to flight angles and more. The Germanswere at least able to devote some time toinvestigating these problems and providingsolutions to them. This was time however,that the Japanese simply did not have. Upuntil the construction of the P.1101 Vl and theplanned Focke-Wulf Ta 183, all of thewartime jet designs flown by the Luftwaffehad nacelle mounted turbojets. The Japan-ese may not have been made fully prily to thelatest German jet engine technology as it per-

tained to long intakes before the war ended.It is within reason to suggest that the R2Y2

with the wing root intakes could have beenunder consideration since it would be a logi-cal development, especially since suchintake arrangements were not entirely new.The third and fourth designs may or may nothave been post-war conjecture.

Unfortunately for Klgisho and the IJN, theR2Y2 would never be brought to full produc-tion. With the end of the war, the secondR2Yl prototype remained incomplete and theR2Y2 would forever remain a design boardaircraft.

79

Klgisho R2Y Keiun - data

Contemporaries

\'lesserschmitt Me 509 (GermanD, Tupolev Tu-91 (NAT0 codename

Boot) (Rusia), l'leserschmitt P, I 100 (Germany)

The specificot[ons in parcnthesis ate for the R2Y2 aith the underulng

turbojets,

z

F

Type

Crew

Long range reconnaissance airclaft (altack aircraft)

Tu'o

Powerplant OneAjchi[Ha-70] 10,24-c1'linder,liquid-cooled

engine developing 3,400hp at take-offand 3,l00hp at 3.000rn/9.845it

driving a 6-bladed metal propeller (trvo Ne330 arial-flow turbojeh

developing l,320kg/2,9 I 0 lb of thrust each)

Dimensions

Span

Length

Height

Wing area

Wing loading

Power loading

13.99m 45.9ft

13.99m 45.9ft

13,01m 42.8ft

13.04m 42.8ft

4.23m 13.9ft

4.23m 13.9ft

33.99m' 365.9ft'

33.99m' 365.9ft'

238.26k9/m' 48.81b/ftl

269.99k9tm' 55.3ib/fl'

2,35k9/hp 5.21b/hp

3,22k9hp 7,1 lb/hp

(R2YD

(R2Ya

(R2YD

(R2YD

(R2Y2)

(R2Y2)

Weights

Empty

Loaded

Fuel capacitv

(R2\2)

(R2YD

(R2YD

6,0l5kg 13,261 lb

5,700k9 12,5661b

9,400kg 20,i231b

9,950kg 21,9351b

1.515 litres ,li I gallons

3,2 l8 lilres 850 gallons

Performance

NIa\ speed

(R2Y2)

Cruise speed

Landing speed

(R2YD

Range

IR2YD

Climb

(R2YD

Ceiling

(R2Y2)

20kn'h 447mph

at 10,000m at32,8l0ft

797kn/h 495mph

at mean sea level, estimated

464knvh 288mph

at4,000m at l3,l25ft

l66km/h lO3mph

158kn/h 98mph

3,l39km 1,950 miles

l.269km 788miles

I0 min to 10,000m (32,81Oft)

7 min to 10,000m (32,810it)

| 1,700m

10,700m

38,385fI

35.104f1

fumament

None (one 800k#1,764Ib bomb and a batten'of fomatd fiilng cannon)

Note

Concerning the three other R2Y2 jet variants rvilh internal engines, little is

documented and much is open to conjecture. In some instances, the tdng

span. length, height and wing area are listed as being the same for the

R2Y1 but the speed is given as being a marimum oi800knr'/h (497mph).

Deployment

None. One prOt0tlpe 0[the R2Yl was built and flom while the second

R2Yl prototvDe was unfinished by the end of the nar, The R2Y2 slal'ed

on the design board,

80 .hp.qrrlEsE SEcREt PRorscrs: ExpsRIttpNral AIncRerr oF rHE IJA AND IJN 1939-1945

Kiigisho Tenga

Of the many Japanese experimental aircraftof World War 2, perhaps none is more of amystery than the Kugish6 Tenga. The Tenga(which can mean the Milky Way as one trans-lation of the kanji) was to be a first for Japan:a turbojet powered bomber. To realise thisambition as quickly as possible, the Japaneseintended to use one of their latest and bestbomber designs - the Klgisho PlY Ginga('ginga' also means MilkyWay) - as the basisfor the Tenga.

If one examines the aircraft available to theJapanese during the war, the distinct lack ofa medium bomber quickly becomes evident.Whereas most of the warring powers oper-ated medium bombers (for example, theMartin B-26 Marauder, the Junkers Ju88 orthe Vickers Wellington), the Japanese werevery late in bringing such aircraft to the front.The IJA brought the Ki-67 Hiryu mediumbomber into service in 1944 and so the IJN

looked to the Klgish6 PIY Ginga as theiranswer to the need for a medium bomber.

Development of the Ginga began in 1940 as

the Dai-lchi Kaigun Koku Gijutsu-sho'sattempt to meet a 1S-Shi specification for amedium bomber capable of high speeds, theability to conduct low-level bombing and tor-pedo missions, and the capability to performdive bombing. With Tadanao Mitsuzi andMasao Yamana at the helm the Y-20, as theGingawas called at this stage, emerged as anaerodynamically clean, mid-wing, twin-engine design. Despite its relatively smallsize, the Ginga had fourteen fuel tanks (ofwhich only eight had some protection frombattle damage), a modicum of armour for thepilot (which consisted of a 20mm thick platebehind his head), a light defensive armamentof a 7.7mm machine gun in the nose and inthe rear of the cockpit, and the ability to carrya single 800kg (1,764 lb) torpedo or two 500kg(1,102 lb) bombs. With the two NakajimaHomare I 1 18-cylinder, air-cooled radialengines developing 1,280hp each, speed wasestimated at 556km/h (345mph).

The first prototype was completed inAugust 1943 and flight testing began shortlyafterwards. Test pilots found that the Gingapossessed excellent speed and also dis-played good handling qualities. Groundcrews on the other hand had anything butgood things to say about the aircraft. TheHomare 11 engines and the hydraulic systemused in the Ginga were a constant mainte-nance hassle, requiring far more time andeffort to maintain than was considered rea-sonable. So bad were the problems, the IJN

postponed its acceptance of the aircraft.

Despite the problems production got mov-ing and design changes saw the machineguns replaced with Type 99 Model 1 20mmcannons and l3mm Type 2 machine guns.

Other changes included revised engine cowl-ings, replacing the retractable tail wheel witha fixed wheel, moving from flush riveting tofl at-head riveting, incorporating a bullet-proofpanel in the windshield and also replacingthe Homare 11 engines with the Homare 12

which could produce 1,825hp.

After these modifications, the IJN finallyaccepted the PlYl Ginga bomber into ser-vice. But the type was still nagged by prob-lems, notably the Homare 12 engines whichrarely produced the horsepower they wererated for. Such issues delayed the Gingaentering combat until the spring of 1945. Eventhough the Ginga would see battle for a meresix months the design nevertheless proved tobe a capable medium bomber and onewhich the Allies respected when theyencountered it. When the Allies first heard ofthe plane they thought it was a healy fighterand assigned the codename Francr's to it(after Francis 'Fran' Williams of the MaterialSection of the Directorate of Intelligence,Allied Air Forces, Southwest Pacific Area).However, when the Ginga was finally spottedafter 1943, itwas realised that itwas abomberand the name was changed to the feminineversion of Francis - Frances.

The Ginga was developed into several vari-ants and there were plans to use the bomberas a carrier for the Oka Model 21 and OkaModel 22 suicide aircraft. Kawanishi built anight-fighter/intruder version as the PlY2-S,which entered service with the IJN as theKyokko (meaning 'Aurora') in the summer of1944. The Kyokko was fitted with MitsubishiKasei 25a 1,850hp, 14-cylinder radialsbecause the Homare 12 could not be assem-bled fast enough to meet demand. Weaponsincluded two forward oblique mounted20mm Type 99 Model 2 cannons firingupwards and the nose cannon was removed.First flown in July 1944, it was found that theKyokko did not perform well at the high alti-tudes where the Boeing B-29s roamed. Thisrevelation was so disappointing that theupward firing cannons were removed andthe Kyokko returned to its bomber role as theGinga Model 16 (P1Y2). Nakajima also built asimilar night-fighter version as the P1Yl-SByakko (which meant 'White Light'). TheByakko fared little better than the Kyokko anddid not see service. Other modifications andplans included upgrading the engines to theHomare 23, Kasei 25c orthe Mitsubishi MK9A,

8tIn'tpERrnr- JnpaNEse Navv

the idea of an attack model with ten to sixteenforward firing 20mm cannons and using steeland wood in the aircraft's construction. The

most interesting was the P1Y3 Model 33. This

version was to be built from the ground up tocarry the Oka and would have had a specialbomb bay to accept the oka Model 21 or 22

with increased wing span and an enlargedfuselage. The PlY3 never left the drawingboard.

With the Ginga's success in terms of per-formance, it's easy to see why there wasinterest in converting it to turbojet power. The

concept of the Tenga was certainly real. But

outside of the name and the basic intent toreplace the radial engines with turbojets,nothing else is known. Therefore, one has to

review other designs to make assumptionson what kind of task the Japanese might have

faced in making the Tenga a flying reality.The first point to consider would be that the

Kugishd Ne20 turboiets, then in productionfor use in the Nakajima Kitsuka, would nothave been sufficient to provide the Tengawith any meaningful speed if mounted oneper wing. One Ne 20 produced 487kg(l,074Ib) of static thrustand two could propelthe Kitsuka to 623km/h (387mph), which wasnot particularly signifi cant over conventionalhigh-performance propeller driven aircraft.The Kitsuka was a much lighter aircraft and a

twin turboiet Tenga using Ne20s would nothave been feasible.

It would have needed some of the pro-jected advances in the Ne20's developmentto come closer to reality to provide the Tenga

with a meaningful system of propulsion. The

Ne 30 turbojetwas expected to generate up to850k9 (1,873Ib) of thrust (better than the Ger-

man BI\,fW 003 turbojet rated at

800k9/1,763Ib) while the IshikawaiimaNe 130 was projected to produce 900kg(1,984Ib) of static thrust, comparable to the

Junkers Jumo 004 engine. The NakajimaNe 230 and the Mitsubishi Ne 330 were esti-mated to be able to produce 885kg (1,951 lb)and l,300kg (2,866|b) of thrust respectivelywith the Ne 230 sacrificing thrust for a lighterweight.

It is said that the Ne 30 would have been the

initial choice to power the Tenga had it beenavailable. ln comparison, the German Aradotu234B jet bomber used two Jumo 004

engines. Itwas similarin size to the PlYl, the

notable differences being a smaller wingspan, the loaded weight was nearly 680kg(1,500Ib) lighter and the tu234B had far less

wing area. Together, the two Jumo 004

engines could move the Ar2348 at speeds upto 742kmlh (46lmph). Certainly, two Ne30engines would not have provided such aspeed when mounted to the PlYl but it

would have been the logical starting point.

Quite possibly, RATO units may have beenneeded to boost the Tenga off the ground.

Clearly the Ne 130 would have been a betterselection and with the Ne 330, the Tengawould have enjoyed a noticeable speedimprovement. Problems with the develop-ment of the Ne 30 engine are cited as a reason

for the Tenga project being cancelled.Indeed, the Ne 30, an off-shoot from the Ne 12

program, never advanced, being surpassed

by the Ne 20, Ne 1 30, Ne 230 and Ne 330 devel-

opments.But could the basic airframe of the Ginga

be used with radial engines replacing withturbojets? It may have been attempted had

the Tenga advanced in design. Even changing

the radials for turbojets would have necessi-

tated fairly significant adjustments in thewings to accommodate them but at least

redesigning a wing to accept turbojets is asimpler task than redesigning the entireaircraft.

However, if one examines the history ofcombat aircraft, you would be hard pressed

to find a conventional combustion enginedbomber switching to jet power merely bychanging the engines and adiusting thewings. For instance, not even among thedozens of jet bomber projects undertaken bythe Germans did a piston-engined bomberswitch its engines for turboiets without heavy

modifications, if at all. One such examplewas the Messerschmitt Me 264 which usedfour Junkers Jumo 9-21 1 radial engines whenthe first prototype was flight tested. However,

the proposed four turbojet engined versionbore little resemblance to the original design.

Perhaps the only notable propeller to tur-

bojet design created byadaptating an existingairframe was the Russian Tupolev Tu-12

whose heritage was owed to the Tu-2, one ofthe premiere Soviet light bombers. Built from1941 through 1948, the Tu-2 possessed fast

speed, excellent agility and had a substantial

weapon fit and bomb carrying capacity.

When Tupolev answered the call to producea jet bomber, he took the Tu-2 as the basis forhis Tu-12. He used the fuselage, wings and

tailplane of the Tu-2 and adapted them to suitthe installation of two Rolls-Royce Nene-l tur-bojets and the higher speeds that wouldresult. Although one can certainly see the lin-eage of the Tu-2 in the Tu-l2, the aircraft stillrequired a general redesign to cope with the

new engines and the associated handlingcharacteristics and was not simply a case ofswapping the radial engines for turbojets. The

design of the Tu-l2 began in 1946 and the first

flight took place in June 1947.

It is not unreasonable to conclude that the

initial Tenga designers may have tried to

utilise as much of the Ginga as possible, offer-ing the benefit of an airframe already in pro-duction with proven aitworthYcharacteristics. This would have reduceddevelopment time when the need for such a

bomber was most urgent. It would have alsoserved as a starting point for aerodynamictesting. Still, when one reviews the jetbomber proposals of other nations, the num-ber of piston engine to jet engine conceptscan be counted on a single hand. For themaiority, the jet bomber was designed fromthe ground up instead of being adapted froman exisiting aircraft. The designers of the

Tenga may have come to the same conclu-sion had they had the opportunity to continuetheir work. If so, the final Tenga design andprototlpe may have borne little resemblanceto the Ginga with which it shares its name.

Kugish6 Tenga - data

Contemporaries

Arado Ar234 Blitz (Germany), Heinkel He 343 (Cermany),

NorthAmerican B-45 Tornado (US), Illushin IL-22 (Russia)

Therc is no exact infomat:nn ouailable on the specilications for the

Kitgish1 Tenga. The dato prouided belou is based on the Tenga haD[ng

used the PIY Ginga abfiame ptetty much aefuotlm, apot't fr\m the

change of engines (as the Tengo [s often depicted). Et)en then,

information is fragmentary and subject to guessoorh,

Medium Bomber

Three

Powerplant (planned)

Two Ne 30 turbojets producing 850kg (l,8i3 lb) of thrust each

Type

Crew

Dimensions

Span

Length

Height

Wing area

19.99m

14.99m

4.29m

55,00m' 592ft'

(likely to be different with turbojets)

Performance

Ma\ speed

Range

Climb

Ceiling

Armament

Two 20mm cannons or l3mm machine guns, one in the nose, the other

rear firing; one 800kg (1,764Ib) torpedo or behveen l,000kg to l,560kg

(2,205Ib to 3,525Ib) ofbombs

Deplolment

None. The Tenga existed onlyas a paper design.

65,6ft

49.2fr

l4.lft

N/A

N/A

Weights

Empty

Loaded

N/A

N/A

N/A

N/A

82 JeperuEsn SEcRET PRoJECTS: ExpenrunntnL Atncnepr oF rHE IJA ar.ro IJN 1939-1945

s\f\

83Iuppnnl .lnpANsss NA.w

In 1943, the IJN issued an l8-shi specificationthat included the requirement for a new inter-ceptor. Japanese aircraft tasked with inter-ception roles had by this time begun to be

eclipsed by the newest Allied fighters and the

IJN sought to ensure their edge was main-tained. Three contenders submitted theirdesigns and it would be Kyrlshrl's that was the

most radical of them all: the J7W Shinden.The man behind the Shinden ('Magnificent

Lightning') was Captain Masaoki Tsuruno, amember of the Technical Staff of the IJN. Tsu-

runo conceived an interceptor that made use

of a configuration rarely seen at the time of his

design work, a design with canard fore-planes. Canards were not a new concept,even in 1943. They were seen as far back as

I 91 0 with a Gabriel and Charles Voisin design

and later a Bleriot tail-first aircraft had incor-porated canards. (Both planes used the term'canard'which in French means 'duck'- the

1910 Canard Voisin and the 1911 Bl6riot'Canard'). Canards would sporadicallyappear in experimental aircraft right up toWorld War 2, examples being the 1929 Raab-

Katzenstein Rakate, the 1931 Focke-WulfEnte (the 'Duck') and the 1937 Beltrame Col-

ibri. Tsuruno felt canards could offer a num-ber of advantages such as reducing the

chances of stalling, improved controllabilityand manoeuvrability and easing some con-struction concerns such as the engine instal-

lation and control linkage arrangements.Besides the canards, Tsuruno introduced

another feature in the Shinden that was cer-

tainly new to the Japanese - the use of a tur-

bojet to power the aircraft. Of course,Tsuruno understood that a more conven-

tional piston-engine would have to be used

until such time as a suitable turboiet becameavailable, but a turbojet was incorporatedinto his original design to ensure that the tran-

sition r,vould not present any difficulties. Atthis time, the Shinden was known as the X- I 8.

By the time Tsuruno's initial layout for the

Shinden was complete the IJN had already

issued its late 1943 18-shi specifications forthree classes of aircraft. The first of these cov-

ered an air superiority fighter (18-shi Ko), the

second for an interceptor (18-shi Otsu) and

the third for a night fighter (18-shi Hei). For

the 18-shi Otsu competition, both Nakajimaand Kawanishi had submitted designs: the

single-engine J6K1 Jinpu ('Squall') and the

twin-engine J5Ni Tenrai (or'Heavenly Thun-

der') respectively. These entries were based

on the rather sparse directives of the specifi-cation which called for a top speed of665km/h (413mph), a climb to 8,000m

Kyushu J?W Shinden

(26,246f1) in nine minutes and the ability tocarry at least two 30mm cannons. To go withthese two proiects, Tsuruno introduced the

Shinden to the IJN as a third competitor.Despite some opposition to the design, the

IJN was intrigued enough to accept the Shin-

den proposal. However, the design had toshow promise and the canard configurationneeded to be proven before the IJN wouldauthorise further development. Therefore,

Tsuruno designed a glider based on his Shin-

den concept as a means to test the canardproperties and handling. Kugisho was com-missioned to build three gliders which werecalled the MXY6. Further details on MXY6

development can be found on page 69. The

initial, positive results achieved with the

MXY6 convinced the IJN to move forwardwith the Shinden project even before the

completion of the glider testing by authorisingtwo prototypes of the J7W1.

The IJN gave the Shinden project to Kyushit

Hikoki K.K. even though Kyltshu had no expe-rience with high performance aircraft, letalone one like the Shinden. Unlike othermaior manufacturers however, Kyushrl's

research facilities, personnel and productioncapacity were not heavily taxed by the needs

of the Japanese war machine. To assist

Kyushl, the IJN placed a team from the Dai-

Ichi Kaigun K6kr1 Gijutsu-shd as well as Tsu-runo himself at the disposal of Kyushu

engineers and managers to bolster theircapability in handling the program.

With everything in position work com-menced on the first prototlpe in June 1944.

The heart of the JTW1 was the MitsubishiMK9D ([Ha-43]) 12 l8-cylinder radial engine

boosted by a supercharger. Although Tsurunowanted to use a turbojet he rejected theNe 12B (TR-12) as insufficient in terms ofthrust production. And since further turbojetdevelopments were projected to showimproved performance, the Shinden woulduse this radial engine until such time as a suit-

able turbojet was available. The Mitsubishi

engine and its superchargerwere mounted inthe rear of the fuselage. A six-bladed, metalSumitomo VDM propeller was mated to the

engine through an extension shaft and placedin a pusher configuration. If required the pro-peller could be jettisoned to effect pilot bail-out. On each side of the fuselage were airintakes for cooling the engine. The mainwings were swept and on each was mounteda vertical stabiliser situated in approximatelythe middle of the wing. The pilot sat in a cock-pit in the centre of the fuselage while the

canards were mounted on the nose. A tricy-

cle landing gearwas employed, the front tyre

being 550xl50mm and the two main tyres

being 725x200mm in size.

The Shinden would carry four Type 5

30mm cannons. The Type 5, while heavierthan the earlier Type 2 30mm gun, possessed

a higher rate of fire at 500 rounds per minuteand had a higher muzzle velocity. Each can-

non was provided with 66 rounds. With less

than eight seconds of 30mm rounds per gun,

one hit would be sufficient to cripple and

shoot dow,n a fighter or bomber, thereforethere was little ammunition to waste. There-

fore, there were two Type 1 7.92mm machineguns, one on either side of the gun camera, infront of the nose. The purpose of these guns

was not offensive but to serve as a ranging

weapon for the cannons. Upon lining of his

target, the pilot would fire a short burst frornthe machine guns. If the rounds struck the tar-get, he would fire a burst from the cannonsand be reasonably assured of a hit, therebyconserving the precious cannon ammuni-tion. Each Type I was provided with 75

rounds of ammunition in a saddle drum mag-

azine. It should be noted that sources oftenlist the two Type I weapons for training pur-poses, i.e. for practice and gunnery training,not gun laying. While certainly possible, gun

laying would seem more plausible due to the

rapid ammunition consumption of the Type 5

cannons and in training there is no real rea-

son why machine guns would be used as a

substitute for cannons. For payload, the Shin-den had a modest bomb carrying capacity of120kg (264Ib).

BySeptember 1944, amodel of the Shindenwas being tested in a wind tunnel to assess its

aerodynamic properties of the shape andplanforms. With the results deemed accept-able, the first metal was cut on the prototypeat the Kyushu Haruda factory located inFukuoka City. By May 1945, the Shinden wasnearly complete although it lacked the

canopy, landing gear fairings, much of the

main wings and other components. As theMK9D ([Ha-43]) 12 was alreadyinstalled, test-ing of the powerplant commenced and trials

showed that a cooling problem existed, prob-

ably in part because no airflow was reachingthe engine during static testing.

In June 1945, the first prototype was fin-ished but the armament was not fitted.Instead, weights simulating the Type 5 can-

nons were installed in the nose. Flight testing

was to commence immediately although theproblem with the engine cooling would delaythe first flight until 3 July. Tsuruno would be

the first to fly the Shinden. The aircraft was to

g4 JapanEsr SEcnEr PRo;Ecrs: ExpsnrMeNrar- AIRcnerr op rre IJA eNo IJN 1939-1945

!o

=2

IupEnraL Japai'ress Nnvv 85

.laplrinsE Srcner Pnotrcls: Erprnrnrsr"r'aL Arrtcnanr crr. rrrn I.JA axo I.lN 1939-1945

oozf

IuprnrnL JapnxEsE Nevv 87

KyushuJZW Shinden - data

take-off from the Mushiroda Airport inFukuoka City. The engine was started andTsuruno climbed into the cockpit. On releas-ing the brakes and commencing to taxi, theShinden showed an unexpected heavytorque pulling to the right. Surprised, Tsuranowas unable to stop the plane swerving off therunway where the propeller touched theground bending several of the blades by as

much as 28cm (1 1 inches). In addition, a por-tion of the right wing's vertical stabiliser wasalso damaged. The accident would delayflight testing for nearly a month while repairswere made. To prevent the propeller fromstriking the ground, tail wheels, as used onthe KyushD Kl 1W Shiragiku trainer, were fit-ted to the bottom of the vertical stabilisers.

On 3 August 1945, the Shinden was pre-pared for flight. Only 38 litres (10 gallons) offuel were loaded with 80 litres (21 gallons) oflubricating oil. The weights simulating the

cannons remained. The flight would be madeby Kyushu's Yoshitaka Miyaishi. With thetorque now a known issue, Miyaishi was ableto compensate and the Shinden successfullytook to the air for the first time. The flight wasfor a very short duration and the aircraft wasnot taken above 400m (1,312ft). On landingMiyaishi reported that the take-off was rela-tively easy but rudder rise was experienced at185km/h (1lSmph) with the plane lifting offthe ground at l93km/h (120mph). As heclimbed pushing the speed Io 222krn/h(l38mph), ttre pull to the right caused by thetorque from the propeller was very notice-able. After levelling off at 400m (1,312ft) andat a maximum speed of 16lmph, the pullwasstill a problem. He also found the landing tobe atrickyprocess. The Shindenwas found tohave a relatively fast landing speed at240krn/h (149mph) and because of thetorque pull and the inclination of the nose,bringing the Shinden down was not a simpletask.

A second flight was made on 6 August 1945

with Miyaishi at the controls. Manoeuvrabilitywas the mdn focus of the test, though the air-craftwas flown up to 491m (1,61Oft). The pilotfound that during the climb the nose wantedto dip. Again, the pull to the right was evidentand during landing if a slight rudder up posi-

tion was applied the nose would pop up just

before touchdoum. It was also discoveredthat the oil temperature rose as the flightwenton and a means to rectify the problem wouldhave to be found.

On 8 August 1945, the third and final flightof the Shinden took place with Miyaishi at thecontrols. At lg3km/h (l20mph), the nosewheel left the runway and at 203km/h(126mph) the plane lifted off. Miyaishi notedthat the nose tended to drop regardless ofhow fast or slow the engine revolutions were.He also found that even with the nose down,the Shinden still flew horizontally with alevel track and slight application of the rud-der. Landing speed was again 240km/h(149mph).

In total, the first Shinden logged between30 and 45 minutes in the air. In addition to theproblems already noted, Miyaishi com-plained of strong vibrations in the fuselage, inpart due to the engine torque and from theextension shaft that mated the propeller tothe engine. With the flight results, Kyushuengineers set about the process of solving thetorque and vibration problems as well as thecooling concerns.

However, even before the Shinden tookflight the IJN was desperately in need of ahigh performance interceptor. The Kawan-ishi J6Kl Jinpu failed to show any improve-ment over the Kawanishi NlK2-J Shiden-Kai

Contemporaries Performance

Cuniss-Wright XP-55 Ascender (US), Henschel P,75 (Germany), Gotha Mar speed

Co P.50/l (Germany), Henschel P.87 (Germanv), Messerschmitt P.1 I l0

Ente (Oermany), Miles M.35 and M,39B Libellula (UK), Mikoyan-

Curevich MiG-S Uika (Russia), Arnbrosini SS,4 (ltaly)

The spec[f[cations in parenthesis ae for the JM2 Shinden-Kai in uhich Cruise speed

the standad lM I aifrcme is used,

Interceptor

One Landing speed

Take-offlength

Landing length

Range

Endurance

Climb

Ceiling

Powerplant One Mitsubishi MK9D (lHa-431) 12, l8-cylinder,

air-cooled radial engine, developing 2,l30hp at take-off, 2,020hp at

I,l80n/3,870ft and l,160hp at 8,700n/28,545f1, driving a sk-bladed,

altemating stroke propeller (one Ne 130 arjal-flow turbojet developing

900kg/1,984lb of thru$)

750km,h 466mph

at 8,700m at 28,545fi

800krnh 497mph

(J7W2) atl0,000m at32,8081t

424knlh 263mph

at4,000m at 13,125f1

449km^ 279mph

(J7W2) at6,000m atl9,685ft

240kn/h l49mph

560m 1,837ft

580m 1,902ft

85lkm 529 miles

2.5 hours

10 min 40 sec to 8,000m (26,245ft)

12,000m 39,370[t

Type

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading

Power loading

(JiWD

(r7wD

(J7WD

I L09m

ll,09m

9,63m

9.63m

3.90m

3.90m

20.49m'

20.49m'

241.19k9/m'

240.2lkgln'

2,40kgArp

5.44kg/ttp

36.4ft

36.4fr

3L6ft

3 l.6ft

I 2,8fr

12.8ft

220.65ft!

220.65fr'

49.4tb/tt,

49.2 tb/ft,

5,3lb,tp

l2.0lb/hp

(JiWD

(Jiw2)

(J7w2)

Armament

FourTlpe 5 30mm cannons with 66 rounds per cannon, two Tlpe I

7.92mm ranging machine guns wilh 75 rounds perweapon with the

capacity to carry two 60kg (132 Ib) bombs or four30kg (66lb) bombs

Deployment

None, Two JTWl Shinden aircraft lvere produced. Although the aircraft

was ordered into produclion, no further examples had been constructed

bv the end ofthe war. The J7W2 remained a design only.

SuMvors

Kiush[ JilVl Shinden (FE-326)

This was the second Shinden prototpe and lvas captuled at Ky.rshu's

main factory. It was jisted on the aviation industry Ielease report on

l0 March 1946 and to undergo restoralion at I\'IAMA by I August 1946.

FE.326 was moved to Park Ridqe in September 1946. 0f note is the

Shindenwas provided with a stipulation that it should be housed in such

a way that it could be quickly removed from storage ifan engine and

other parls were to be obtained to bring it to flight status. This never

happened but the Shinden was lortunate enough to escape the cutting

torch and was moved to the Paul. E. Garber facilitywhete it cunently

remains in pieces and unrestored (see page 86),

Weights

Empty

Loaded

Ma,c Ioaded

Useful load

3,525kg

(J7W2) 3,465k9

4,950k9

(J7W2) 4,930kg

5,272k9

l,425kg

(J7W2) l,a6skg

i,771 lb

7,6391b

10,912tb

10,868rb

ll,62tb3,141 lb

3,229tb

88 JnpnNsss Sscnnr PRo.lrcrs: ExpERrn,teNrlL ArRcRnpr oF THE IJA AND IJN 1939-1945

(meaning 'Violet Lightning', known to theAllies as George) and the NakajimaJ5Nl Ten-rai was proving to be a disappointment by thetime flight trials commenced in July 1944.

With the failure of these two entries for the18-shi specification, the IJN ordered the JTWlShinden into production in May 1944 and in sodoing made the b,pe the only canard configu-ration aircraft to achieve this status duringWorld War 2. By September 1944, the pro-duction plans had been formulated withKyushu's Zasshonokuma factory expected toturn out 30 Shindens per month while Naka-jima's Handa plant would produce 120 Shin-dens each month. In light of the war situation,such production numbers would have beenvery difficult to meet. As it was, the war endedbefore production could get going.

In addition to the Iirst prototype, the secondmachine was also completed but it did not flybefore the end of hostilities. The war's endmeant that the modifications required to cor-rect the problems found during ground andflight testing were never made. As a side note,nearly four decades later Colonel BobThacker would construct a radio controlledflying model of the Shinden. His initial proto-type showed the same pull problem as theoriginal Shinden resulting in two crashes thatrequired the complete rebuilding of themodel each time. To solve this problem,Thacker placed the front canards at 7.5" pos-itive incidence, adiusted the centre of gravityand pointed the extension shaft for the pro-peller 3" to the right and 4.5" down from thezero thrust line. The pull problem was suc-cessfully eliminated by these adjustmentsand the Kyushri engineers may have foundthe same solution had they had the time toimplement it.

The Shinden was not an easy aircraft to fly.Given the configuration of the aircraft, itwould have required a skilled pilot to use incombat and Japan's forces were low onexperienced pilots by the time the Shindenwould have entered service. The same prob-lem would plague the Germans when theirhigh performance turboiet fighters werecoming into operational use.

The end of the war also spelled the end ofthe J7W2 Shinden-Kai. This was to be the tur-boiet-equipped version of the Shinden. Theuse of the radial engine had been a stop gapuntil a suitable turbojet was available. TheNe 128 was reiected as its power was consid-ered too low to effectively propel the aircraft.In any case, work was by this time under wayon the Kugisho Ne 20 turbojet that was basedon the German BMW 0034, engine, the onlyturbojet built and flown in aJapanese aircraft:the Nakajima Kitsuka (page 114). The J7W2was to use the Ne 130 turbojet, also based on

IupEnreL Japer{Ess Nevy

the BMW 003A, which was being developedby Ishikawajima-Shibaura. The Ne 130 was tohave produced nearly double the thrust oftheNe20; however, the Nel30 would not beready by the close of the war and as such theJ7W2 remained a design board aircraft. Thereis speculation concerning what the J7W2would have looked like. One suggestion is

that the J7W2 would have been the J7W1with the Mitsubishi radial replaced with theNe 130 turbojet. A second suggestion con-cerns the fact that without the need for pro-

peller clearance the Shinden could dispensewith the tall landing gear, thus lowering theheight of the aircraft. Aside from modifyingthe landing gear, the vertical stabilisers, fuse-lage and canopy shape may also haverequired adjustment. It is likely that haddevelopment of the J7W2 commenced withthe availability of the Ne 130, a J7W1 airframewould have been adapted to accept theengine and testing conducted on this, withother modifications coming into play as a pro-duction J7W2 was standardised.

zo

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g0 Jlp,qr-nse Sucnrl Pno;rcls: Err,EnnrE:lrAr. Alttcnalr op lrrE IJA,qrn IJN 1939-1945

Mitsubishi GZM Taizan

f- F,.rg$ *{:a;:'&...

6,043km (3,749 miles) this r,vas insufficient toattack targets in the United States or, ifrequired, deep into Russia. Folloi'r'ing thisrevier'v, the Kaigun Koku Hombu put forth the16-shi specification for an attack bomber.Only trvo key specifications rvere stated. Thefirst'uvas that the marimurn speed had to beat least 580km/h (36lmph) and the secondr'vas a maximum range of at least 7,340km(4,598 miles). Nlitsubishi set about the task ofdesigning a bomber capable of meeting theserequirements.

Initially, Mitsubishi engineer Kiro Honjo(who designed the G3UI and G4N{) proposedthat the 16-shi bomber should be of afour engine design. Within Mitsubishi thebomber was knor,vn as the M-tj0. His pro-posal, however, was flatly rejected by theKaigun Koku Hombu. Instead, anotherNlitsubishi engineer, Kijiro Takahashi, put for-rvard his own design for the l6-shi bomber

. ::'.t:;@#F€e?

-""{"*

The illustration of lhe GTMI provided in this bookis based upon Kijiro Takahashi's design. It issholvn in the colours of the Yokosuka Kdkutai,

whicli upon revierv rvas allor'ved to proceed.Takahashi's version of the NI-60 \,vas to use

trvo 'Nu' engines. The Nu engine r,vas a 24-

cylinder, horizontal-H, liquid-cooled engine.Simply put, a horizontal-H cngine is trvo flatengines placed one on top of the other andgeared together (a flat cngine is one in n'hichthe pistons move horizontally). Despite hav-ing a poor porver to rveight ratio, they ofTer theadvantage of being more compact and,because of this, Takahashi elected to usethem on his bomber. Each engine n'as ratedat 2,200hp at 5,000m (16,404ft).

In appearance, Tahahershi's bomber bore astrong resernblance to the Heinkel He 177

Greif (German fbr 'Giiffon') heavy bomberthat first flerv on l9 November 1939. 'lhe nose

Prior to the start of World War 2, there weremen rvho foresaw the need for long rangestrategic bombers capable of striking acrossvast distances. Men like GeneralleutnantWalter Wever of Germany who pushed i.vithurgency the need for such bombers despitethe veritable wall of opposition to suchendeavours. This r,vas also the case in Japanrvhere it was clear that aggression against theUnited States would require the capability ofhitting the US. Therefore in 1941, the KaigunKoku Hombu issued its 16-shi specificationfor a long range bomber.

A review of bombers in service',vith the IJNby 1941 showed that none were capable ofcrossing the Pacific to attack distant targets.At the time, the Mitsubishi G3NI (codenamedlVe// by the Allies) was being phased out to bereplaced by the Mitsubishi C4M (known as

Betty Io the Allies and Hamaki or'Cigar'to theJapanese). Although the G4N41 had a range of

Irrpenral JapaNEsE Nariv

z

a

zz

wi

r l!}* ?

*

91

Type

Crew

Mitsubishi G7M Taizan - data

Contemporaries

Bri$ol Buckineham (UK), Lockheed P2V Neptune (US), Junken Ju 88H-

1 and H-2 (Germanl, Junkers Ju 288A (Gemany)

The specificotions for the GTM\ Taizan are baed on the design

dimensions Tnd estimated performance of the linal G7M1 proposal as

deriuedbl Mitsubishi.

Long-Range Bombet

Seven

Powerplant Trvo ['litsubishi MKI0A (Ha'42'l 1) lS'cylinder, ait-

cooled radial engines developing 2,000hp ior take'off, 1,8 I Ohp at 2,200m

(7,21 7ft) and l,720hp at 5,400m (l 7,7l6fi); each engine drove a metal,

four-bladed, alternating stroke propeller with a 4.5m (l4.7it) diameter

was rounded and fully glazed, a style unlikeany Japanese bomber then in service. The

wings were mounted mid-fuselage, eachwing sporting the Nu engine in awell-stream-lined nacelle. On top of the fuselage, fore and

aft of the wings, was a turret for a portion ofthe defensive armament. A fairly spacious tailgunner position was fitted beneath the verti-

cal stabiliser on the underside of the fuselage

with a rear facing ventral gun station. A rela-

tive rarity in Japanese bomber design was the

tricycle landing gear. Takahashi's perfor-

mance estimates put the normal operationalrange at 6,412km (3,984 miles) which, with alighter payload, could meet the 16-shi specifi-

cation. The maximum speed would have

been 555km/h (345mph) with a relativelylight defensive weapon armament of twoType 99 20mm cannons and two TYPe 97

7.7mm machine guns.

Unfortunately for Takahashi, OperationBarbarossa, the German invasion of the

Soviet Union on 22 June 1 941 , would prevent

the required machine tools and equipment toproduce the Nu engine from being exportedto Japan. Without the powerplant, the design

was doomed. With Takahashi's proposal hav-

ing fallen by the wayside, Kiro Honlo resumedcontrol of the M-60 proiect. This time, instead

of a four-engine bomber, Honio would utilisetwo engines and base his design heavily onthe G4M.

The G7M Taizan (meaning'Great Mountain')as the design was later designated was to use

two 18-cylinder, air-cooled radial engines, the

Mitsubishi MKl0A (Ha-42-11), developing

2,000hp each. The wings were mounted mid-way on the fuselage and the aircraft was to be

constructed of metal with fabric covering the

ailerons and rudders. It was anticipated that

the Taizan would carry the same 800kg

(1,764Ib) bomb load as the G4M1 but unlikethe Hamaki, the Taizan would have a far more

poient defensive armament as the bomberwould operate far from fighter protection. This

step also took into account the shortcomings in

the G4M1's protection. Of course, using less

powerful engines and a heavier weapon fitcaused a revision in performance when com-

pared to Takahashi's design. A 31 October 1942

performance estimate gave ihe G7M1 a range

of 5,559km (3,454miles) ataspeedof 518km/h(322mph) at 5,000m (16,404ft) with a weapon

fit of two Type 99 20mm cannons, two Type 2

13mm machine guns and two Type 1 7.9mm

machine guns. However, as work on the G7M1

proceeded and the design underwent furthertesting, these estimates would continue to be

revised. Unfortunately for Mitsubishi, the

revised estimates did not see any expected

improvements to the performance but rather

some deterioration.

By 1942, Mitsubishi had completed the

bomber's design and were ready to constructa full size wooden mock-up of the GTMI

Taizan, which was in due course completed.Unfortunately, the Kaigun Koku Hombu hadnow issued a 17-shi specification for a

bomber that Kawanishi was developing as

the K-100 (which some sources designate as

the G9K Gunzan, meaning'Mountain Group',

but this has never been verified; othersources have the G9K as a 1944 19-shi

bomber project). Mitsubishi was instructed to

halt all further work on the G7M1 until the

K-100 could be evaluated.Kawanishi completed the initial design of

the K-100 bomber and the Kaigun Koku

Hombu reviewed it along with the G7M1 in

the summer of 1943. By this time, the GTMI

had suffered further range performance

reductions, dropping from a proposed nor-mal range of 3,705km to 2,778km (2,302 miles

to 1,726 miles). This was caused in part by the

heavier armament compared to the initial fit,

removing the two Type 1 machine guns and

adding three more Type 2 machine guns tomake a total of six Type 2s. This was, to adegree, tempered by a higher speed of544km/h (344mph) at 5,000m (16,404ft).

Based on the projected performances of

both aircraft, it was felt that neither design

would be suitable either for the 16-shi or the

17-shi specifications. The Kaigun Koku Hombuwas critical of the G7M1's design for concen-

trating much of the defensive weaponry in the

frontal arc of the bomber, thereby reducing the

aircraft's defences in the side and rear arcs. In

addition, it was considered that the actual per-

formance of the G7M1 would likely have been

little, if at all, better than the operational G4M 1 .

Another nail in the coffin for the G7M1 was the

fact that the Kaigun Koku Hombu was looking

to four-engine bombers as the real means to

achieve the necessary range (at least

8,816km/5,478 miles, allowing for a one waytrip from Tdkyd to Los Angeles). In fact as early

as 1938 the IJN had asked Nakajima to produce

a four-engine bomber, the G5N Shinzan('Mountain Recess') which was based on an

imported Douglas DC-4E.

With the Kaigun Koku Hombu showing no

interest in the G7M, Mitsubishi shelved all fur-

ther work on the bomber. Ironically, the G5N

Shinzan would prove a failure and had aworse range than the G4M. Onlywith the con-

struction of the four-engine Nakajima G8N1

Renzan ('Mountain Range') which first flew in

October 1944 would the original l6-shi range

specification be met. By then, the need for

such bombers had passed as attention had

turned to defending Japan and fighters/inter-ceptors were required.

Dimensions

Span

Length

Height

Wing area

Wing loading

Power loading

25.00m

20.00m

6.09m

N/A

N/A

3.99kg/hp

82.Ofr

65.6fr

20,0ft

8.8lb/hp

Weights

Empty

Loaded

Lselul load

Bomb load

10,60Okg

16,000kg

5,400kg

800ks

23,368lb

35,273Ib

l l,904lb

l,764lb marimum

Performance

Max speed

Norma) range

\'lar range

Climb

Ceiling

Fuel capacily

544knth

at 5,000m

2,799km

7,400km

344mph

at 26.246ft

1,739 miles

4,598 miles

l0 min to 10,000m (32,808f1)

N/A

4,497 littes l,188 gallons

Armament

Six 13mm Type 2 machine guns, two mounted in each oi hvo upper

luselage tunets (one fOnvard. One alt of the wings) and two in aventral,

rear firing position: hvo 2Omm Tlpe 99 \'lodel 2 cannons, one mOunted

in the nose, the othel in the tail

Deployment

\one, Awooden mock-up was built befole the Taizan project was

cancelled.

92 JApANESE SEcRET Pno:Ects: ExpeRIntEIrtteL ArncRnnr OF THE IJA AND IJN 1939-1945

The concept of the J4M Senden ('Flashing

Lightning') was born of the need for a highperformance interceptor that could operateat high altitude. The main catalyst for this wasthe American Boeing B-17 Flying Fortress.The bomber, in action in the Pacific Theatrefrom 1941 to 1943, proved to be difficult tointercept since it normally flew at heights thatoperational Japanese fighters could not reachor attain with difficulty. Even if an interceptionwas achieved, the B-17 carried a formidabledefensive armament with which to protectitself. To a lesser extent, the ConsolidatedB-24 Liberator was also a factor when itbegan to replace the B-17s still remaining inthe Pacific. ln 1942, two companies, Mit-subishi and Kawanishi, were given a 17-shi

Otsu specification by the Kaigun KokuHombu to develop an aircraft to meet theneed for a high altitude, high performanceaircraft.

Mitsubishi Jukogyo K.K.'s response to the17-shi Otsu directive was anything but con-

Iupnnrlr. .llpnxEse Nlvv

Mitsubishi J4M Senden

ventional when compared to Kawanishi'sdesign, the J3K1. The proposed plane, knownwithin the company as the M-70, was a mono-plane pusher design that featured twinbooms connected to vertical stabilisers by alow mounted horizontal stabiliser. Thebooms were slung under the low, fuselagemounted wings. The heart of the aircraft wasto be the Mitsubishi [Ha-431 12 MK9D tur-bocharged, radial engine. Rated at 1,650hp at8,000m (26,246fr), it was projected that thisengine would push the Senden to a top speedof 704km/h (437mph) via its six bladed pro-peller. For weapons, there was a Type 5

30mm cannon and two Type 99 20mm can-nons. All three were arranged in the fuselagenose with the Type 5 being centrally mountedand the two Type 99 cannons on either side ofthe fuselage. If required, the aircraft couldcarry a small bomb load of up to 120kg(2641b). Mounted across the top of the fuse-lage behind the cockpitwere inlets to feed airto the turbocharger and engine. The purpose

of the turbochargerwas to boost the manifoldpressure on the engine over and above oper-ating pressures at sea level as a means tomaintain and improve performance at alti-tude. For landing gear, the Senden had a tri-cycle arrangement with the nose gear

retracting into the fuselage and the mainwheels being housed in the booms. The pilotsat in the glazed nose of the aircraft in a cock-pit that was blended into the fuselage. Themajority of the Senden was constructed ofmetal with fabric being used on the ruddersand ailerons.

The Senden came in two versions. The firstwas the project described above while thesecond variation replaced the blended cock-pit with a bubble canopy to improve thepilot's radius of vision. It also removed theprotruding inlets and replaced them with twobands of flush inlets thatwrapped around thefuselage, the first being directly behind thecockpit and the second around the enginearea just past the wings. Finally, the horizon-

oEoz=

93

Mitsubishi J4M Senden - data

Contemporaries

Focke"Wulf mit BMW 803 (Germanl'), Vultee XP-54 'Su,oose Goose'

(US), Belyayev EOI (Russia), Bell XP-59 (lS)

Specifications in parentheses rcfet to lhe J4Ml Project 2 Senden only

Fighter/lnterceptol

0ne

Powerplant One l'litsubishi (Ha-43) N'IK9D iS-cylindet, air-

cooled radial deleloping 2, I 00hp at engine start, l,900hp at 2,000m

(6,561fi) and l,650hp at 8,000m (26,246t1), driving a alternating stroke,

six bladed propellerrvith a 3.2m (l0.5ft) diameter

oEozf

Tlpe

Crew

Dimension

Span

Length

12,49m

12.98

12.49m

3,47m

22.00m'

24,69m'

l99.69kgh'

197.73kg/m'

4lft

42.6fr

4lfr

I l,4ll

236.8ft,

265.8ft:

40.9lbifr

40.5lb/ft

(J4M4)

He;ght

Wing area

(J4M4)

Wing loading

(J4M4)

tal stabiliser was moved to the top of the ver-tical stabilisers. The remainder of the aircraftwas basically the same between the two ver-sions. The blended cockpitversion is creditedas the J4M1 Project 1 while the second, withthe bubble canopy and modified inlets, is

sometimes referred to as the J4M4 Project 2.

After analysing the two designs, Mitsubishiselected the original configuration, the J4M1,

to develop further. To confirm their initial pro-jections, a full scale model was constructedin 1943 and put to the test in a wind tunnel.Unfortunately for Mitsubishi, the tests provedto be a disappointment. Performance projec-tions based on the testing were below the ini-tial calculations and problems with the MK9D

in terms of not reaching its horsepower ratingonly added to the concerns.

However, the Kaigun Koku Hombu and theIJN ensured that Mitsubishi would not have toconcern themselves further with the Senden.

ln 1943 as Mitsubishi was working on theSenden, the Kaigun Koku Hombu issued an18-shi Otsu specification. From it, the KyushlJZW Shinden resulted (page 84 for details).With the 18-shi Otsu requirements being simi-lar to the 17-shi Otsu specifications and withthe J7W showing far more promise and having

the support of the IJN, Mitsubishi were told tocease work on the Senden and instead furtherdevelop the Mitsubishi AZM Reppr-r ('Hurri-

cane') to meet the 17-shi Otsu standards. The

result was the A7M3-J Model 34 Rifuku (Land

Wind) that had not advanced beyond thedesign phase before the war ended.

Despite the fact that the J4M Senden did notprogress past a wind tunnel model, US airintelligence was aware of the design mainlythrough captured documentation. In the Jan-uary 1945 issue of the US RecognitionJournal,the J4M Senden was announced as a possible

adversary in the coming weeks of the war.No artist renderings of the Senden wereincluded in the article. The J4M was given thecodename Luhe in anticipation of Alliedpilots encountering the aircraft in combat,something which was never to occur.

As a note, although there are artist impres-sions of a iet-powered Senden (as shownhere) there is no evidence to support thenotion the J4M was ever revived or consid-ered for turbojet power as there were otherdesigns being considered (for example, theJ7W2 and the Ki-201) which offered betterprospects and capability.

Weights

Empty

Loaded

Mar loaded

(J41\'r4) 3,400kg

4,400kg

(J4Nr4) 4,486kg

[J1\'r4) s,25sks

7,195.7 lb

9,700.3Ib

9,889,91b

1 1,585.2 tb

Performance

Nlax speed

(J4M4)

Cruise speed

(J4N{4)

Landing speed (J4M4)

Endurance

Climb

(J4l\'14)

Ceiling

l5 min to 8,000m (26, 2461t)

l0 min to 8,000m (26, 24 6ir)

756knlh

at 8,000m

703krn'h

at 8.000m

462knv'h

199knttir

l47kr["h

2.2 horus

470mph

at 26, 246ft

436mph

at 26, 2461t

287mph

3l0mph

91mph

12,000m

(J4\'r4) 11,000m

39,370it

36,089ft

Armament

One Type 5 30mm cannon with 100 rounds of ammunition and t$'0

Tlpe 99 20mm cannons rdth 200 rounds ofammunition each: ptovision

for hvo 30kg (66 lb) bombs or hto 60kg (132 lb) bombs

Deployment

The Senden did not advance past a wind tunnel model.

cI

z-

94 Japnrursl SpcnEr PRo;Ecrs: ExprnlutEnteL AtRcRepr oF rHE IJA AND IJN 1939-1945

o

oz=

InrpERrer- Jnpar.rEsE Navv 95

oIozl2

In 1943, the Japanese were only too wellaware of a threat looming on the horizon.That threat was the Boeing B-29 Super-

fortress. Witii ttre development of the B-29

starting in 1939, the Japanese were in no

doubt that once ihe bomber entered produc-

tion it rvould eventually appear over Japan,

The problem for the Japanese was that theydid not have an effective countermeasureagainst the B-29 and feared theywould not be

able to have one ready in time for its antici-pated arrival. Fortunately, the answer wasfound in one of the most radical fighters ever

to achieve operational status.

Towards the middle of 1943, representa-

tives of the Japanese military in Berlin werenotified of the development and progress ofthe Messerschmitt Me 163, a point defenceinterceptor powered by a rocket engine.

Interest was expressed immediately. In shortorder Japanese attach6s from the IJN and the

IJA visited Bad Zwischenahn in Germanywhere Erprobungskommando 16 was sta-

tioned. This unit had been created earlier in1943 to develop Me 163 combat tactics,

Mitsubishi J8M Syusui

deployment and training as well as the coor-dination of the various contractors and test

centres involved in development and pro-duction of the Me 163. During the tour EKdo16 personnel explained to the Japanese the

temperamental nature of the Walther HWK5094 rocket motor and the dangerous and

explosive properties of the two fuels themotor used. This did nothing to dissuade theJapanese who saw the answer to their needs

right before their eyes. To them, the benefitsof an interceptor able to climb rapidly andpossessing a very high speed overrode any

concerns about the fuels or the engine. The

Japanese wasted no time in entering negoti-ations to obtain the N{e 1638.

However, not everyone was in agreementabout the value of the Me 163. Detailed reports

had been sent to Japan from Germany regard-

ing the findings of the attaches which overall

were positive; nevertheless, some argued that

it would not be possible to produce the fuels

the aircraft required in sufficient quantity to

support operational requirements. Otherscriticised the unorthodox nature of the Me 163

and that developing such a plane and its

engine would consume much neededresources. Despite these objections, the sup-porters for the Me 163 won out.

The Japanese swiftly and successfullynegotiated the licences to manufacture boththe Me 1638 as well as its HWK 509A rocketmotor. The motor licence alone cost theJapanese 20 million Reichsmarks. In additionto the two licences, Germany was to providecomplete blueprints for the Me l638 and the

HWK 509A, manufacturing data for the air-

craft and engine, one complete Me 1638,

three HWK 509A motors, and two sets of sub-

assemblies and components by no later than1 March 1944. Also, Japanese militaryattach6s in Berlin were to be notified of any

improvements to the Me 163 design so

changes could be incorporated into the

Japanese version. The Japanese also

requested to oversee the manufacturingprocesses for the Me 1638 and the rocketmotor as well as being allowed to study and

review Luftwaffe operational procedures forthe fighter. Three submarines were tasked

96 JapaNesE SecRsr PRoJECIs: ExpsRIltlNlal Alncnnrr oF rHE lJA,qro IJN 1939-1945

with shipping the materials to Japan - theRO-500, RO-501 and I-29.

RO-500 was still named U-511 when itdeparted from Lorient in France on 10 May1943 bound for Penang, Malaysia. Aboardwere four Japanese including Vice AdmiralNaokuni Nomura and Major Tam Otsu Sugitaof the IJA medical service. AIso aboard wasthe data for the Me 1638. During the transit,U-511 was named Satsuki 1 ('satsuki' mean-ing the month of May). On 16 July, U-511

reached Penang where Nomura, Sugita andthe otherJapanese passengers disembarkedand returned to Japan by air. U-51 1 departedPenang for Kure, Japan, on 24 July 1943 andarrived in Kure on 7 August 1943 where thesubmarine was presented to the IJN as theRO-500.

RO-501, a Type IXC/40 submarine, was for-mally U-1224. On 15 February 1944, U-1224rvas handed over to the IJN who gave it thename Satsuki 2, and on February 28, it wascommissioned into the Imperial Nar,y as

RO-501 with Lieutenant Commander Noritaas captain. On 30 March 1944, RO-501

departed from Kiel, Germany, with the man-ufacturing data and blueprints for the\'le 1638 among other cargo. At 7.00pm on 13

\'lay 1944, north west of the Cape VerdeIslands, the USS Francis M. Robinson, a Buck-ley class destroyer escort, reported a sonarcontact 755m (825 yards) from the ship. TheFrancis M. Robinson immediately initiated anattack, launching 24 Mark 10 Hedgehogbombs and five salvos of Mark 8 depthcharges. Sonar reported four explosions sig-

nifi'ing the death of the RO-501.

l-29 of the Imperial Japanese Narry

departed from Lorient, France, on 16 April1944. She caried on board a HWK 5094rocket motor, the fuselage of a Fieseler Fi 103

and a Junkers Jumo 0044 turbojet, again withother cargo. Technical Commander EiichiIrvaya, a passenger, carried with him theplans for the Me163B and Me262 whileanotherpassenger, Captain Matsui, had plansfor accelerators used for rocket launching.Between the two of them, they also had plansfor a glider bomb and radar equipment. On 14

July 1944, the I-29 arrived safely in Singapore.Here, Iwaya and Matsui disembarked, alongrvith a portion of their documents, and con-tinued on to T6kyo by air. On 15 July, Alliedcode breakers intercepted a message fromBerlin to T6kyo regarding the cargo that theI-29 carried and on 26 July 1944 aI 5:00pmnear the western entrance of the BalintangChannel, Luzon Strait, the USS Sarofish spot-ted the I-29 on the surface. She fired four tor-pedoes and three struck the Japanesesubmarine. I-29 sank almost immediately andonly one sailor survived who swam to a

lrrpERrnr- JepeNess Navv

nearby Philippine island and reported theloss.

Technical Commander Eiichi lwaya, uponleaving the I-29, did not take all of the docu-mentation he had for the Me 1638 (or theMe 262) and the loss of the I-29, along withthat of the RO-501, delivered a major blow tothe development program. However, theinformation Iwaya had preserved, combinedwith what was received from the RO-500, wasenough to keep the project alive and in July1 944 the IJN issued a I 9-shi specification for arocket powered interceptor. This decisionwas based on the analysis of the documenta-tion on hand for the Me l638 and the currentconstruction capacity and capability of the airindustry, and also down to the drive of ViceAdmiral Misao Wada who supported thedevelopment of the rocket aircraft.

Upon issuing their 19-shi specification, theKaigun Koku Hombu assigned the project toMitsubishi. Mitsubishi were initially reluctantto accept the design, but further considera-tion and the need to adapt the Me 1638 designto Japanese production capability saw themanufacturer agree. Even though the IJN wasbehind the aircraft, the IJA would also beinvolved in the development of both the air-craft and rocket motor. The Japanese rocketinterceptor was to be called the J8M1 Syusui(which means 'Autumn Water') and in IJA

service the Syusui was to be designatedKi-200.

On 27 July 1944, all personnel involved metto discuss the Syusui and it was agreed to fol-low the design plan of the Me 1638 as muchas possible. The key reason was that thedesign was proven and worked and thus crit-ical time could be saved. The same applied tothe rocket motor. A second reason for adher-ing to the Me 1638 design was that Japanesefabricators had almost no experience withthe tlpe of aircraft that the Me l638 was. Butnot everyone was in full agreement.

The IJA saw flaws in the Me 1638 and feltthat Japanese industry could not fully pro-

duce the Syusui to the specifications of theGerman aircraft. Modifications to meet thecurrent capabilities of the Japanese aviationindustrywould be required to both the rocketmotor and the aircraft which, as a conse-quence, would force changes to the design.As such the IJA argued that in the end a newdesign would be required anF/vay. The IJN,

however, would hear none of it and wasadamant that the Me 1638 design would befollowed.

Mitsubishi forged ahead with assembling ateam to develop the J8M1. The project wasled by Mijiro Takahashi at Mitsubishi's Nagoyaplant. Under Takahashi was Tetsuo Hikitawho would be the lead designer for the air-

frame. In addition to the Mitsubishi men, rep-resentatives of the Yokosuka KOkittai wereinvolved, namely Captain Kumamoto andCommander One, who was tasked with testflying the J8M1 upon completion. TechnicalCommander Eiichi Iwaya was also a part ofthe overall development team given his famil-iarity with the Me 1638 acquired during his

time in Germany. One last meeting was heldon 7 August 1944 to finalise the developmentof the Syusui and then work began.

The first stage was the wooden mock-ups.On 8 September 1944, the full scale mock-upof the cockpit was completed and on 26 Sep-

tember 1944, the mock-up of the Syusui wascompleted. Both the IJN and the IJA

inspected them and suggestions were madefor possible alterations to the design. Thesechanges were incorporated and Takahashi'steam laboured day and night to produce thedetailed blueprints for the J8Ml. Three proto-types were to be built; the first would be forload testing while the remaining two wouldbe used for the flight test program. As therocket motor was not yet available, two of theprototlpes would be weighted to simulatethe motor and fuel. To hasten construction,when one portion of the aircraft was draftedand finalised, a copy was sent to the assem-bly shop assigned to construct the compo-nent so work could begin without delay.

Externally, the J8M1 was unmistakable inits lineage but Takahashi and his group had tomake modifications as they adapted theMe 1638 design. For example, the Me 1638

used two MK 108 30mm cannons which wereheavier and shorter than the 30mm cannonsthe Japanese were to use. Fuel capacity wassimilar to the German aircraft and so were thedimensions, althorrgh the J8M1 was slightlylonger due its more pointed nose and had awider span and smaller wing area. (The

Syusui unlike the Me 1638 did not use a nose-installed generator, the space being used forradio equipment.) The wing thickness wasalso increased. The main difference, how-ever, was the weight: the Syusui was 363 to408kS (800-900Ib) lighter than the Me 1638.

This was not due to any effort to purposelylighten the Syusui as it lacked armour protec-tion for the pilot and carried less ammunitionfor its cannons than the German interceptor.For weapons, the J8M1 was to be equippedwith two Type 5 30mm cannons in the wingswhile the IJA's Ki-200 would use two Ho-155

30mm cannons or two Ho-S 20mm cannons.Because the Japanese lacked the experi-

ence in flying tailless aircraft, Krlgisho wastasked with creating a glider version of theSyusui. In part, the glider would provide per-formance data, findings from which could beincorporated into the Syusui, but would also

97

serve as a trainer for rocket aircraft pilots.

Therefore, the MXY8 Akigusa and MXY9

Shuka were developed, as described else-

where in this book on page 77.

While work was undetway on the first

three prototypes, a production plan for the

fighter was put together and was completedby October 1944. By March 1945, 155 Syusui

were to be produced with another 1,145 builtby September 1945. Ultimately, by March

1946 at least 3,600 Sylsui were anticipated to

be in service.In addition to developing the Sy[sui, Mit-

subishi was also assigned the task of creatingthe Japanese version of the Walther HWK509A rocket motor and both the IJN and the

IJA were involved in the motor program. To

assist the engineers in Mitsubishi's engine

department, personnel from the IJA's First

Army Air Arsenal engine section wereassigned to the firm. The resulting motor wascalled the KRl0 but was also known as the

Toku-Ro.2. Components for the KR10 wereconstructed by four companies: Hitachi,

Ishikawajima, Mitsubishi and Washimo.Washimo, for example, was responsible forthe fuel flow control mechanisms and the

relief valve for the Ko fuel tank.Mitsubishi faced several problems in build-

ing the KR10, the main issue being that the

HWK 509A used a nickel-chromium alloy in

the fuel injector atomiser, regulating valves

and reliefvalves. Since the Japanese did nothave access to this alloy they had to use plain

chromium steel. It was expected that the

KR10 would be ready for testing by October1944, but the lirst prototlpe exploded imme-diately when it was started for the first time,partly believed to have been caused by the

metal used. A deviation was made from the

original HWK 509A plan in that the KR10

motor used wider supports and included a

bearing in the middle for ihe Ko fuel com-pressor. This revision in the KRl0 resulted in

the KR12 but the addition of a second versionof the motor risked compounding any pro-

duction problems. Indeed, testing of the KR12

also resulted in an explosion. Mitsubishi engi-

neers discovered that a bearing seal had

failed that allowed the Ko fuel to leak into the

motor and then come into contact with the

bearing lubricant with catastrophic results.

Given that it offered no real advantage, the

KRl2 was shelved and work focused solely

on the KRl0. These accidents, their subse-

quent investigations and the resulting revi-

sions put the KR10's development further and

further behind.For fuel, the Syusui used two ingredients

which, when combined, provided the com-bustion and resultant thrust. The first, Ko, was

the Japanese version of the German fuel

T-Stoff formed from eighty per cent hydrogenperoxide with the remainder Oxyquinolineand pyrophosphates to act as stabilisers. Ko

rvas the oxidising fuel. The second, Otsu, wasthe Japanese equivalent of C-Stoff. Otsu wasthe reductant fuel and was composed ofthirty per cent hydrazine hydrate with the

remainder being methanol, water and potas-

sium-copper cyanides. Together, Ko and

Otsu were a hypergolic fuel combination,which meant that when the two fuels werecombined they spontaneously ignited. Theproblem with Ko and Otsu was that they werecolourless and, of course, when they cametogether, the result was explosive. This

required strict handling procedures and con-

tainment methods. Both fuels were stored inspecial ceramic pots. To produce both fuels,

three chemical companies were contracted.They were the IJN's First Fuel Arsenal, Mit-

subishi Kasei and Edogawa Kagaku. In the

Syusui, the fuels were stored in wing and

fuselage mounted tanks. The pilot sat

between two 91 litres (24 gallons) tanks of Ko

while behind him in the fuselage was a 961

litres (254 gallons) tank and a 8 litre (2 gallon)

tank of Ko. Each wing housed two tanks ofOtsu, the capacity of each tank in each wingbeing 64 and 197 litres (17 and 52 gallons) inthe two tanks respectively.

By December 1944, the second and thirdJ8M1s had been completed but as no engines

were ready for installation, ballast was used

to simulate the weight of the KRl0 with fullfuel tanks. Earlier, the first J8Ml had beencompleted and load tested on 1 December1944. However, the 7.9 magnitude Tonankaiearthquake that struck the Tokai region ofJapan at 1.30pm on 7 December 1944

destroyed the aircraft and the testing facilitythat housed it. The remaining J8Ml aircraftwere transferred to the IJN's First Naval AirTechnical Arsenal. From there, the aircraftwere shipped to Hyakurigahara, locatedabout 79km (49 miles) northeast of Toky6.

December would also see delays due to the

increasing B-29 bomber raids. Attacks against

Mitsubishi's Nagoya facility resulted in the

KR10 program being moved to the Dai-Juichi

Kaigun Kokusho complex at the Hiro Naval

fusenal in Kure, Hiroshima. Here, work con-tinued on the motor supervised by Professor

Kasai of the Kyushl University (although

another source states the entire engine devel-

opment group was moved to an undergroundfacility in Natsushima in Yokosuka prefec-

ture, overseen by the Dai-Juichi Kaigun

Kokusho).During testing, the KR10 delivered less

thrust than the HWK 509A. Although the

Syusui was lighter than the Me1638, whenTakahashi and Hikita completed perfor-

mance calculations for the Syrisui based on

the thrust rating of the KRl0, they found thatthe lighter weight did not totally offset the

lower thrust. Regardless, the estimated speed

and climb rate was considered exceptional.On 8 January 1945, a Nakajima B6N1

(known as Jrl/ to the Atlies) towed the Sylsuiinto the air from the Hyakurigahara airfield and

after a successful flight the design was vali-

dated. Work quickly proceeded on furtherproduction of the Sy[sui, this time with the

KR10. However, the motor program was at

least three months behind schedule and itwasnot until 11 April 1945 that the KR10 was suffi-

ciently developed to enable it to function withsome measure of reliability. With the possibil-

ity of powered flight, Captain Shibata, com-mander of the 31 2 Kokutai due to be equippedwith the J8M1, sought to speed up the process

for testing. In discussions with the S1'usui

development team it was decided that if the

KR10 could produce thrust for at least twominutes without mishap, the motor should be

fitted to the Syusui so that powered flight test-

ing could commence. 22 April1945 was set as

the deadline for the first powered flight.

Meanwhile, Germany made anotherattempt to send more material to Japan

including documents and parts for the

Me163. These items and other cargo wereloaded onboard U-864 that departed from the

Bruno U-boat pen located in Bergen, Norway,

on 5 February 1945. However, having past

Fedje the submarine developed a misfire inone of her two MAN diesel engines and itwasnecessary to return to Bergen to effectrepairs. The British submarine HMSVenturer,

dispatched to deal with U-864, spotted the

German submarine's periscope on 9 Febru-

ary 1945. Korvettenkapitiin Ralf-Reimar Wol-fram realised he was being followed and

began to take evasive action, moving in a zig-

zag fashion. James S. Launders, Venturer's

captain, decided to press home the attackand fired all four of his loaded torpedoes in a

spread pattern. U-864 crash dived, dodgedthree of the torpedoes but turned into the

fourth which struck the submarine. The

resulting explosion split U-864 into two.Unfortunately for the Sylsui, the deadline

for the KRl0 would not be met. In exhaustive

testing, another motor detonated after having

achieved two minutes of burn time. ln addi-tion, fears of B-29 raids saw the KR10 teambeing moved to the Yamakita factory com-plex in Hakome prefecture while the Mit-

subishi Syusui development group wasrelocated to the IJA research and develop-ment centre in Matsumoto in Nagano Prefec-

ture. These moves consumed preciousresearch time throughoutApril and May 1945.

Both groups were eventually able to continue

98 JapaNEse SEcREt Pno;pcls: ExpERIurnral AtRcRapr oF THE IJA axp IJN 1939-1945

c=

z-

work on the KRl0 in an attempt to enhanceits reliability and, in June, success wasachieved. A KRl0 from the Yamakita groupfunctioned for four minutes while the Mit-subishi group in Matsumoto managed threeminutes. With these motors now meeting the

two minute requirement, plans were swiftlyprepared to install the Yamakita KRl0 into aJ8Ml while the Matsumoto motor was to beplaced into another airframe that would becompleted as a Ki-200.

The J8M I 's installation was completed first

in the second week of June 1945 at Mit-subishi's Number One Plant in Nagoya. TheSyr.rsui lacked much of its operational equip-ment including weapons and was trans-ported to Yokoku airfield. This site wasfavoured because it was situated along ashoreline, which meant that if the pilot had toditch the aircraft he could do so into theocean, offering a better chance for survival as

well as possibly lessening the damage to theSyrlsui. The Syusui arrived at Yokoku at thebeginning of July and ground testing beganimmediately. Secured to the tarmac, the tailof the Sylsui was removed exposing the KRI 0

and motor running tests commenced. It wasfound that the motor did not burn fuel evenly,generating plumes of light red smoke fromthe combustion chamber as it ran. By 5 July1945, technicians and engineers had cor-rected the burn problem to the point that theKRl0was deemed readyand the Sylsui's firstpowered flightwas scheduled for 7 July 1945.

In front of a crowd of onlookers, the Syusuiwas moved to the start of the 1,200m (3,93ift)nrnway, the longer of the two at Yokoku. Itwas then fuelled with 568 litres (150 gallons)

of Ko into the fuselage tanks and 159 litres (42

gallons) of Otsu into the wing tanks as themixture ratio was approximately 10 to 3.6. At4:55pm, the pilot, Lieutenant-CommanderToyohiko Inuzuka, fired the engine andwithin I I seconds and after only 320m(1,049ft) of runway, the Syusui lifted off theground and into the air, Inuzuka releasing thedolly and raising the nose to provide a 45'angle climb. Then, at 350m (1,148ft), a puff ofblack smoke issued from the motor, sput-tered and went out. The speed that had beenbuilt up carried the Syusui up to 500m(1,640ft) where Inuzuka levelled off andbanked to the right ready to return to the run-way and land. As Inuzuka continued his righthand bank, the Syrlsui began to drift and air-speed rapidly dropped off. As he approachedthe runway, Inuzuka raised the nose of theSyrlsui to try and avoid colliding with a build-ing but it was too late. A wing clipped the sideof the building, putting the Syhsui into a crashso forceful that it broke apart, scatteringpieces across the south-west edge of the air-field. Both wings were ripped away and thefront of the aircraft was completelydestroyed. Inuzuka survived the impact andwas extracted from the wreckage. However,the extent of his injuries was so severe that hedied the following day.

No time was wasted in trying to find thecause of the motor failure. Mechanical issueswere ruled out and it was surmised that thepuff of smoke and the subsequent loss ofpower from the KR10 was due to fuel beingcut off from the motor. Miraculously, the fuel

Irr.rpsRler, JepeNesE Nnvv 99

tanks did not explode on impact and it wasfound that at least half of the fuel loaded priorto take-off remained. It was determined thatthe culprit was the fuel line from the Ko tank.

Due to poor design, when the Syusui wentinto its climb the fuel in the tank shifted awayfrom the line which starved the motor of the

needed oxidiser and thus the KRl0 cut out.While the investigationwas being carried out,

bench tests of two additional KR10 motors(one each at Matsumoto and Yamakita)resulted in both exploding. This left a single

KRl0, the one slated for the Ki-200.

Flight testing of the Syusui was suspended

until the problem with the fuel system couldbe resolved. A further four Syusui aircraft had

been completed by Mitsubishi by the time asolution was found. These changes wereincorporated into the KR10 engines thenunder development and flight testing wasscheduled to resume in late August 1945.

However, on 15 August 1945, Japan surren-dered. All further work on the Syusui ceasedand no further flights were made. At the endof the war the Ki-200 remained engineless, its

KRl0 never having been installed. Aside fromthe seven J8Ml aircraft built - including the

one to be finished as the Ki-200 - another six

were in various stages of completion. A fur-

ther four KRl0 motors had been completedwith another two nearly finished. Enough

components had been constructed to assem-ble a further twenty motors.

Another variant of the J8M had beenplanned which was called the J8M2 Syusui-

Kai. The J8M2 lost one of the Type 5 30mmcannons/ammunition to be replaced by addi-tional fuel tankage. It was hoped that thiswould increase the endurance of the aircraft.The end of hostilities would see the J8M2

remain only a preliminary design though pro-duction of the J8M2 was a certainty had itbeen completed. As mentioned earlier, the

IJA was not pleased with the Ki-200 and itwould undertake development of its ownver-sion of the J8M, the Ki-202 Sy'r-rsuiKai, to rightthe wrongs it felt were evident in the Syusui.

For more details, please see the chapter onthe Ki-202 (page 40).

A note regarding the use of Syusui as the

name for the J8M. The kanji for the aircraft(Syu and Sui) translate as 'Autumn Water'.However, Shlsui has been used in manysources with translations ranging from'Sword Stroke' or'Swinging Sword' to'Rigor-ous Sword', but the name Shrlsui is not cor-

rect. The use of Shlsui evolved from the

metaphor that Sylsui represents - the wavypattern on the metal blade of a highly sharp-

ened sword as well as the brightness of thepolished metal which reminds :tne of the

waves on a body of clear water.

Mitsubishi J8M Syusui - data

Type

Crew

Contemporaries

l'lesserschmitt Me l638 Komet (Germany)

Specificalions in parenthesis pettain to the l8M2 only and are based on

M ibubishi's est[noted data,

Interceptor/Fighter

0ne

Powerplant

One Toku-R0.2 (KRl 0) bi-fuel rOcket motor developing i,500kg

(3,30iIb) ofthrusi

Deployment

None. A total of seven J8Ml aircraft were completed with one to be

finished as a Ki-200. The 3 1 2 Kokutai were t0 receive the J8['ll had it

entered production, No J8M2 was ever built nor were any Ki-200 airctaft

Survivors

Mitsubishi J8Ml Sl'usui (FE-300)

One of three brought fiom Yokosuka on 3 November 1945, this Spsui is

aircralt N0.403 and is thought t0 have been captured at l'litsubishi's No.l

plant in Nagoya. Appearing on the l0 March 1946 report for aircraft

releasable to the aviation industry, the Sy.rsui rvould be made available

for display purposes on I August 1946 appeadng to the public in

Holllwood, California. The aircralt was later obtained and restored by

Edward Maloney for displav at the PJanes oiFame l'luseum in Chino,

California, where it remains to this day.

Mitsubishi l8M1 Slrsui (tail number 24)

After being received at NAS Patuxent River, the aircralt lvas moved to

NAS Glenvierv in Glenview, Illinois (a suburb ofChicago, Illinois), rvhere

it rvas on display by 3 October 1946. This Slusui eventually reached a

derelict state and was scrapped.

Mihubishi JSMl Syusui (tail number A"25)

Nothing is knorvn about this particular Slusui other ihan it likely ended

up as scrap.

Mitsubishi J8MI Syusui

Mitsubishi has recently restored a J8Ml and it is currentlv on display at

the company's Komaki Plant Museum. A potion of the restoration

contains components irom a badlv damaged J8M1 fuselage found in a

cave but it still required significant custom fabdcation 0f new parls to

iinish the project. Prior to Mitsubishi obtaining the fuselage, the lemains

had been on display on the grounds of the Japanese Air Self-Defence

Force's Gifu Air Base.

Ki-200 - data (estimated)

Interceptor/Fighter

0ne

Powerplant One Toku-R0.2 (KRl0) bi-fuel rocket motor

developing l,500kg (3,307Ib) of thrust

Dimensions

Span

Length

Height

Wing area

\Ving loading

9.47m

6.03m

2,68m

17.72m'

21922k9'n'

(J8MA 2l9.70kgh'

31,lfr

I 9.8fr

8.8fr

190.8ft,

44.9tbift,

45 lb/fr,

lveightE

Emptl'

(J8MD

Loaded

(J8MD

l\'larimum

Useful load

1,445k9

l,5lokg

3,000kg

3,650k9

3,870k9

3,900k9

l,545kg

2.l40ks

3,1 85 Ib

3,328tb

6,613 tb

8,046tb

8,53t lb

8,598Ib

3,406Ib

4,71 7 lb

(JrNzl

(J8[,r2)

Performance

Mar speed

Cruise speed

Landing speed

Range

Mar range

Climb

Ceiling

Fuel capacity

699krr/h

150kn/h

434mph

93mph

900krdh 559mph

at 10,000m at 32,810ft

3 min 6 sec oipowered flight

at 599km,ih 372mph

5 min 30 sec of powered flight

40 sec to 2,000m (6,561ft)

2 min 8 sec to 4,000m (l3,l23ft)

3 min 8 sec to 8,000m (26,246ft)

3 min 50 sec ro 10,000m (32,808ft)

12,000m 39,370tt

I,l8l litres (312 gallons) of Ko and

522 litres (138 gallons) of Otsu

Annament

Two Tlpe 5 30mm cannons with 53 rounds ofammunition per gun

(one Tlpe 5 cannon wilh 53 rounds ofammunition)

Type

Crew

Dimensions

Span

Length

Height

Wing area

9.47m

5.88m

2.68m

17.69m!

31.1fr

l9.3fl

8.8fr

190,5ft,

Weights

Empty

Marimum

l,505kg

3,870ks

3,317 lb

8,531 lb

Performance

Ma\ speed

Cruise speed

Range

illax range

Climb

Fuel capacity

800-900knr/tr 49l559mph

at 10,000m at 32,808f1

35lkn/h 2l8mph

2 min 30 sec otpowered flight

7 min ofpowered flight

3 min 40 sec to 10,000m (32,808it)

l, l8l litres (312 gallons) of Ko

and 522 litres (138 gallon9 otOtsu

Annament

Tlvo Ho-155 30mm cannons (or two Ho-5 2Omm cannons)

100 J,qpnrussr Slcnpr PnoLECrs: ExpsRnrsNrnr- ArRcRLpr oF THE IJA AND IJN 1 939-1 945

Mitsubishi-Payen Pa.400 and Suzukaze 2O

When Allied intelligence discovered an illus-

tration of the Suzukaze 20 in a Japanese mag-

azine, it was unlike anything so far seen in

Japanese aviation design. Despite the radicalappearance, it was felt the Suzukaze 20 was a

bona fide aircraft and might be encounteredin action. As it was, the plane was a work offiction and so the Suzukaze 20 was laterstricken from the publications on Japanese

aircraft identification and coding. However,

Allied intelligence may or may not have beena.,vare of the very real inspiration for the artist

of the Suzukaze 20.

At the time, because of the relative difficultyin obtaining information on Japanese militarymatters, intelligence services relied on vari-

ous publications such as newspapers and

magazines as a means to glean data on the

Japanese military machine. In April 1941, the

Japanese magazine Sora (translated as 'Sky')published a number of illustrations of various

aircraft in a section entitled 'Dreams of Future

Designers'. Included in the selection of art-

n'orkwas the rendition of the Suzukaze ('Cool

Breeze') 20. The 25 December 1941 issue ofthe US magazine Fllghf would also feature the

Suzukaze 20, along with three other aircraft:

the Nakaiima AT27 (codenamed Gus), the

\litsubishi T.K.4 Type 0 (codenamed Franh

IhenHarry) and the T.K.19 (codenamedJoe)'

The Suzukaze 20 would receive the code-

name Omar.The illustration of the Suzukaze 20 depicted

a single-seat fighterwith the striking feature ofhaving a cockpit blended into the vertical sta-

biliser that was itself in the form of a half-delta.

Another notable feature was the use of tworadial engines, one mounted behind the

other, driving two, contra-rotating propellers.

fumament appeared to be healy with four\\ieapons fitted in each wing. Its speed wasgiven as 769km/h (478mph), loaded weight2,858kg (6,3001b), wing area 13.37m' (144ft)and wing loading 21 4.82k9/m') (441b/ff).

As the war dragged on it became evidentthat the Suzukaze 20, along with the otherthree aircraft illustrated with it, were works offantasy and thus all four were removed fromJapanese aircraft intelligence bulletins, the

last of them disappearing by June 1943.

Despite the Suzukaze 20 being a fictional air-

craft, there was a kernel of truth behind it thatperhaps germinated in the mind of the artist

that drew the Suzukaze 20. The kernel couldhave been the works of the French aircraftdesigner, Nicholas Roland Payen.

Payen was born in France in 1914 and

became interested in aviation early in life. By

the 1 930s, he had begun to focus on the use of

IN4penInl JapaNssE NnvY

delta planforms as well as canards and ogival(bullet shaped) flight surfaces. Throughout his

life, Payen would design a large number of air-

craft in a wide array of configurations but,

despite the prolilic nature of his studies, onlytwo were built before the end of World War 2.

Both used Payen's Flechair (an English con-

traction of auion fleche or'arrow aircraft')configuration that consisted of a trapezoidal

fore-wing that housed the ailerons and a rear

delta wing which contained the horizontalcontrol surfaces. Payen had to rely on his

salesmanship to gain access to material, windtunnel time and other resources to build his

aircraft as he had little money of his own tofund projects. Of course, the nature of his

designs often made it a hard sell to the moreconservative aviation industry. The Payen

Pa.100 Fleche Volante ('Flying turow') was

his first aircraft to be built and was intended tobe a racer to compete in the Coupe Deutsch

de la Meurthe. Payen was able to borrow a180hp Regnier R6 but the engine was laterreturned. He was then able to acquire a larger

engine, a 380hp, 7-cylinder radial Gnome-

Rh6ne 7KD Titan Maior, but was too large forthe Pa.100. Payen had to seek donations(which he received) and rebuilt the Pa.l00around the 7KD to create the Pa. I 01 . Unfortu-

nately for Payen, the Pa.101 failed to meetexpectations. It finally took to the.air on 17

April 1935, but on 2TApril a hard landing brokethe port landing gear and a fire broke out inthe resulting crash gutting the Pa.101. The

accident saw Payen's flight insurance

revoked and so he went to work at the Blochfactory constructing a mock-up of the Pa.112

fighter that used two 150hp Salmson engines

in tandem buried in the fuselage. The out-

break of World War 2 saw the French militaryshow no interest in this design.

The second aircraft was the Pa.22 whichwas the test bed for Payen's proposed Pa.1 12

fighter. Originally to be powered by a ramjet,

no such engine was available and a 180hp

Regnier R6 engine was used instead. Payen

constructed the Pa.22 in 1939 and the Ger-

mans would later capture it after the invasion

of France on 12 June 1940. The Germans,

showing some interest in the design, test flewiton 18 October 1941 and found modificationswere needed to correct poor longitudinal sta-

bility. The aircraft was moved to Rechlin inGermany and after adiustments had been

made to the cockpit position and the verticalstabiliser had been rebuilt the Pa.22 flew inthe summer of 1942. After a number of short

flights, the aircraft was wrecked in a crash

landing. ThePa.22 was returned to France for

repairs and was consequently abandoned by

the Germans.Prior to the outbreak of war, the Japanese

had civilian and military personnel in France

who studied and reviewed French aviationprogress for possible use by Japan. This prac-

tice went as far back as 1919 when Japan

invited French military aviation instructors toteach the fledgling Japanese Army air force.

The French also brought with them some ofthe latest aircraft that their country had avail-

able. This training would forge a link betweenJapan and France that would last for manyyears, and it was by these means that the

Japanese would learn of Payen's work.In 1938, Payen received a letter from Mit-

subishi expressing an interest in his designs,

notably the deltawing so often used in his air-

craft concepts. A meeting was held betweenPayen, Commander Koshino and the captainof the UN coruette Sumikawa to talk aboutthe Pa.112. During the discussions the IJN

inquired as to whether the Flechair design

could be adapted to that of a two-seat, carrierborne, light bomber. The specificationsrequired the aircraft to have the ability to take-

offfrom and land on a deck space 80m (262ft)

long, to have a range of at least 800km (497

miles), be capable of carrying a 800k9

(1,763Ib) torpedo or bomb and be fitted withup to 180kg (396Ib) of armament.

Payen took the specifications and workedup a study to meet the IJN requirements. The

design was called the Payen-Mitsubishi

Pa.400. This would have used two 670hp

radial engines mounted one behind the otherdriving two, two-bladed, contra-rotating pro-pellers. For weapons, in addition to carrying

the required torpedo or bomb, a nose

mounted cannon (firing through the propeller

hub), two machine guns per rear wing and atail mounted machine gun were proposed.

Endurance was to be 1l-12 hours with a max-imum speed of 580km/h (360mph). Unlike his

other Flechair designs, Pa.400 used staggered

wings (his earlier offerings had the two wingslevel with each other). The study wasreviewed and Payen was asked by Japanese

representatives to obtain from the French gov-

ernment the authorisation to export the tech-

nical information for the Pa.400 study. This

would have allowed the Japanese to furtherdevelop the Pa.400 in Japan. The authorisa-

tion was granted on 28 September 1938,

signed by the head of the cabinet of the Min-

istry of Air. However, with the cloud of war onthe horizon, Payen decided not to send the

requested documents to Japan and it wouldappear the Japanese did not follow this up. To

t0r

p

!k

.s\-\.0.<t

N

This illustrationdepicts theSuzukaze 20 Omar.

102 Jnpnrussl SscRsr PRolEcrs: ExpenrMeNrnr- ArncRLnr oF rHE IJA AND IJN 1939-1945

all intents and purposes, the Japaneseseemed to have lost interest in the Pa.400.

Why would the Japanese show an interestin the Pa.112 and the Pa.400 only to abandonit on the brink of receiving the technical infor-mation? There were several factors which theJapanese may have become aware of uponfurther review of Payen's initial Pa.400 study.The first was that Japanese radial engines ofthe time did not have sufficient horsepowerand, more importantly, were not of the correctsize to fit into the Pa.400's fuselage. Thus, theJapanese would have had to either constructa new radial engine or adapt the Pa.400 to usea Japanese engine, radial or not. A more per-

tinent problem was the use of tandem radialengines. To make such an arrangementwork-able required a considerable feat of engineer-ing and such designs making it to prototypeform were exceedingly rare. Another factorconcerned the poor visibility afforded the pilotgiven that the cockpit was situated far back inthe fuselage which made landing a challengeat the best of times, let alone landing on amoving and rolling aircraft carrier. The rearwings and the long nose blocked side anddownward vision, a serious liability in aerialcombat, and the relatively short wingspan ofthe Pa.400 would not have offered muchagility, a trait favoured by Japanese pilots anddesigners. In addition, the Japanese may havelearned that the Pa.101 was a flawed designand since the French military paid Payen noattention may have concluded there wasnothing worth pursuing where the Pa.400 wasconcerned. Finally, it may have been the rad-

The Pa.400 depicted here is in the colours andmarkings as used on a Nakajima B5N2 torpedobomber (known as Kdt€ to the Allies) flown by PettyOfficer First Class Toshio Takahashi from thecarrier Hiry[ during the attack on Pearl Harbor.

ical design of the Pa.400 that saw more con-servative IJN officials directing Mitsubishi tofocus their efforts on more conventional air-craft projects.

Enter the Suzukaze 20. A photograph ofwhat was likely the Pa.101 appeared in Japanin a printed document in the late 1930s. Thecaption for the photograph read 'FrenchBrand New Model Pey-yan 266th. Airplane No-

mu 400 Horse Power'. The 'Pey-yan'was thephonetic spelling in Japanese of Payen while'No-mu'was the phonetic spelling for Gnome.How it got to Japan is open to speculation butthe two prevailing theories are that Payen, intrying to drum up funds for his work, made itavailable to a French diplomat to take toJapan to shop around to Japanese industry.Alternatively, the photograph was given to theIJN by Payen during the discussions over thePa.400.

The photograph - and perhaps othersources because Payen's aircraft were sholvnin pubfications such as Brll Barnes: Air Aduen-turer (from April 1935) - likely played a part inthe rendering of the Suzukaze 20. The similar-ities to Payen's designs cannot be ignored. Forone, the Suzukaze 20 utilised two radialengines in tandem driving two, contra-rotat-ing propellers. Also, the Suzukaze 20's cockpitwas blended into the large, half delta-shapedvertical stabiliser, another Payen trait seen inthe Pa.l00/Pa.101 and Pa.22. The artist likelyremoved the rear delta wing and slid the for-ward wings back and enlarged them sincetheir shape is reminiscent of the Pa.400. Withthe exception ofthe nose, the fuselage shapeof the Suzukaze 20 was similar to that of thePa.400. Even the horizontal stabilisers of theSuzukaze 20 had a delta shape, perhaps a nodto the Pa.101. However, whether or not theartist based the Suzukaze 20 on Payen'sdesigns may never be known for certain.

Mitsubishi-Payen Pa.400 - data

Contemporaries

Horton HoX (Germany), Messerschmitt P.l 106 (Germany), Lippisch

Pl3a (Germany), Bl\{W 803 engine (Germany), Wight R-2160 Tornado

engine (US), Pratt &Whitney R-4360 Wasp Maior engine (US), Butler-

Edwards'Steam Dart' (UK),Scroggs'Dart' (L'S)

for the Milubishi-Payen Pa.400, based on the des[gn study conducted

by Poyen.

Light Carier Bomber

Two

Powerplanl

Two Cnome-Rh6ne l4 M4/5 radial engines, each developing 670-680hp

marimum, driving two c0ntra-rotating, two-bladed propellers

Type

Crew

Dimensions

Span

Length

Height

Wing area

6.58m

10.00m

2.68m

25.00m'

2 1,611

p.8ft

8.8fr

269ft?

Weights

Empty

Loaded

2,1 igkg

5,860k9

4,784Ib

12.9r9rb

Speed

Max speed

Nlar speed (one engine)

Landing speed

Endurance

Ceiling

570kn/h 360mph

at 4,950m at 16,240fi

447kn/h 278mph

at 4,950m at 16,240

89km/h 55mph

I 2-14 hours

4,950m 16,240tt

Armament

Five machine guns, two in each wing and one in the tail; one cannon

firine throush the propeller hub; one 800kg (1,764 lb) torpedo or bomb

Deploynent

None. The Suzukaze 20 was a fictional aircratt while the Pa.400

remained a design only.

z

cEFJodzzo

lupEnrnl JapnNesr Navv 103

Mizuno Shinryu II

E

I

za

:*-,€: tFsffi -T'*a'!-E!t

In June 1944, the first Boeing B-29 Super-fortresses appeared over Japan. It was thestart of a bombing campaign that would see

key Japanese cities, infrastructure and indus-tries reduced to ashes through conventionaland firebombing raids. With the aircraftindustry being a priority target, the KaigunKoku Hombu looked to ways to combat theB-29 menace. One concept was a pointdefence interceptor that could quickly rise tomeet the bombers and so the Mizuno Shinryr-r

II was born. However, the development of theShinryu II (Shinryu meaning 'Divine Dragon')began with designs for a far more conven-tional craft.

In November 1944, the Kaigun KokuHombu looked into the possibilities of an air-craft to undertake shimpu missions. Whilethe mission was not unique, the fact that the

aircraft being investigated would be a gliderwas. The Kaigun Koku Hombu envisionedthat gliders would be launched with rocketboosters from caves or shore positions andpilots would guide the aircraft and the 100kg(220\b) explosive payload inside it into Alliedships or tanks should the Japanese homeislands be invaded.

The Kaigun Koku Hombu assigned the Dai-Ichi Kaigun Kdku Gijutsu-shd at Yokosuka thetask of turning the glider into reality. The pro-ject was led by Shigeki Sakakibara whostaffed a number of teams that would each beresponsible for one part of the glider. The dif-ferent sections were the wings, the fuselage,control surfaces, aerodynamic testing andtest flights once the prototype was complete.The Kaigun Koku Hombu gave instructionsthat the glider must be built from as much

104 Japnrursn Stcner PRorEcrs: ExpERruEnral Arncnarr op rHs IJA aruo IJN 1939-1945

wood as possible. This restriction wasimposed for two reasons. The first was that inusing wood and keeping the use of metal toan absolute minimum, the glider could bemanufactured in any small shop using onlywood working tools, and secondly, as a con-sequence, what metals were available wouldbe conserved for other military uses.

Much of the glider's design was conceivedby Yoshio Akita. A number of concepts werediscussed and sketched and after muchdeliberation among Akita and his teams thedesign was complete by May 1945, andMizuno, a small aircraft manufacturer, hadalmost finished the prototype. The glider wasvery simple and used a high-wing monoplaneform. The straight and flat wings were widebut had a short span and were designed toensure that the glider was easy to handlegiven that inexperienced pilots would be atthe controls. Also, the planform would beable to accommodate the rocket engines thatwere to be used to boost the glider into theair. The pilot sat in an open cockpit.

The design was sent to the Kaigun KokuHombu for review. Sakakibara studied theplans and projections and after his analysis itwas felt the glider was flawed and changeswere necessary. After these had been madethe design was approved. Work began on therevised Jinrlu as the glider was now called bythe middle of June 1945. To hasten the con-struction, the finalised blueprints and workplans for the Jinryl were drawn up even as

the components for the first prototype werebeing built. Construction of the Jinr5,u wasagain given to Mizuno. Working around theclock, the company completed two proto-types with such speed that wind tunnel test-ing of the design was still underway. In fact,the first flight of the Jinry[ occurred evenbefore the results of the testing had been pro-vided to Tonsho and Sakakibara.

Tashiichi Narabayashi was the pilot whoflew the maiden flight in mid-July 1945 at theairfield in lshioka, a city located in Ibaraki pre-fecture, about 90km (56 miles) northeast ofTokyo. The Jinryu was towed into the air by aTachikawa Ki-9 (known to the Allies as

Spruce) piloted by Saburd Fujikura, a manknown for his skill in flying gliders prior to thebeginning of the war.

For the first test, Narabayashi assessed theJinryu's handling. On landing, his opinion wasthat the gliderwas stable and possessed goodhandling characteristics. For the second flightNarabayashi would investigate the Jinryu'sdiving capability and after a few bounces onthe ground the Ki-9 and the Jinryu took off. Ata height of 2,300m (7,545f0, Narabayashiwent to cast off from the Ki-9 but found thatthe tow rope release had stuck; however, he

IvpeRrnr, JaparuesE Nnvv

was able to cut the rope and proceed with thetest flight. When Narabayashi put the Jinryuinto a dive and had reached 300km/h(186mph), the glider began to vibrate to sucha degree that he was unable to read thegauges. Pulling the nose up to bleed offspeed, Narabayashi discovered that the vibra-tions ceased. During his descent Narabayashiexamined the vibrations and after landing theissue was reviewed. The conclusion was thatthe tailwas not sufficiently reinforced and thevertical stabiliser was too small. The Jinryuwas modified by adding some strengtheningin the tail and the fitting a second stabiliser.The changes were later validated both in theair and in the wind tunnel testing of the mod-ified Jinryu model. Interestingly, before flyingthe Jinrlu, Narabayashi had suspected thatthe aircraft would have stability problemswhich, as was seen, proved to be the case.

With the handling and flight characteristicsof the Jinryu proven, the testing moved to thenext phase - that of powered flight. The gliderwas relocated to an airfield in Kasumigaura,about 19km (12 miles) north of Ishioka. Here,the Jinryu was modified to accept a group ofthree Toku-Ro 1 Type I rocket engines thattogether would produce 661 lb of thrust dur-ing a l0 second burn. Testing of the rocketarray showed two serious flaws. The first wasthe quality of the rockets that resulted in anumber of failures. The second was theinconsistency of the burn times. Narabayashinoted his concerns and forwarded them toMajor Suganuma who had been placed incharge of the Jinryl project. ln addition toexpressing his doubts about the rocketengines, he also stated that the Jinryu wouldbe unsuited for shimpu missions because,despite the changes made to the glider toimprove the flight characteristics, it was achallenging aircraft to fly. Narabayashi sug-gested that instead of being used for shimpiroperations the glider should be modified totake six rocket engines each with a 30 secondburn time. He estimated that at maximumburn the Jinryr1 could attain a speed of750km/h (466mph), and forweapons he envi-sioned that it could carry ten explosivecharges adapted from artillery shells used bythe IJA in their 100mm guns (likely the Type92). Not only did Narabayashi agree that theJinrlu could be used against tanks and shipsbut added that it could also be used to attackUS B-29 bombers. Despite the issues with therockets work continued on preparing the Jin-

ryu for powered flight.Major Suganuma, however, would become

the catalyst for the Shinry'r-r ll's continueddevelopment. Taking Narabayashi's concernsonboard, Suganuma formed a team to revisethe Jinryu and produce a design for an inter-

ceptor rather than a glider; Suganuma wasespecially interested in this idea since he hadaccess to rocket engines that promised 32 sec-

ond burn times. Two people were retainedfrom the Jinryu project: Sakakibara, the leaddesigner, and Yoshio Tonsho who would over-see the construction of the prototype. YtjirdMurakami was tasked with the aerodynamictesting of the Shinryu II. All of those assigned to

develop the Shinryu II were ordered by Sug-

anuma to maintain the utmost secrecy.

Unlike the Jinryr1, the Shinryu II was to bebuilt from the outset as an interceptor. Sakak-ibara would use a canard design that madethis the second Japanese aircraft to be devel-oped during the war with such a feature (thefirst was the Kyushrl J7W Shinden on page

84). In addition, the main wings had a plan-form similar to a cropped delta. These designfeatures were included as a means of ensur-ing stability in flight as well as good handlingcharacteristics. Since the average Japanesepilot had little experience with canardequipped aircraft, the Shinryu ll had spoilersfitted into the top of each main wing. Eachspoiler was able to rotate between 60' and 90'and if the mechanism for controlling thespoilers was damaged, they would automati-cally return to the closed position. The pilotwas provided with a canopy covered cockpit.

For power, the Shinryu II was to use fourToku-Ro 1 Type 2 rocket engines located inthe rear ofthe fuselage. Each engine provideda 30 second burn time and all together up to600kg (1,322 lb) of thrust could be delivered.Two rockets would be used to get the Shinryull airborne while the other two engines wouldbe used when making the attack. There wasa concern regarding the operating tempera-tures of the Toku Ro rockets and two meth-ods of cooling the engines were considered.The first would have utilised an air-cooledcombustion chamber that would haverequired an air inlet using a bayonet mecha-nism in order to maintain air flow across thechamber. It also would have required specificpositioning of the fuel iniectors so as not tohave the air flow disrupt the injectionprocess. The second method would useinjectors which sprayed a water and alcoholmixture onto the rocket nozzle, cooling it. Inreviewing the two solutions for cooling, it wasdetermined that the water/alcohol systemwould be the simplest to implement.

No provision was made for a wheeled land-ing gear system and design skids were used.A nose skid was provided with a basic springsuspension to absorb the landing forces.Under each wing was a non-sprung skidarrangement supported by two struts. Fortake-off the Shinryu II was to use a two-wheeled dolly similar to the one used by the

t05

MitsubishiJ8M Sylsui. Once airborne the pilotcould jettison the dolly. In addition to con-ventional runway take-off procedures, othermethods for launching the Shinryu II wereconsidered but what exactly these were is notknown. lt can be speculated that towing the

Shinryu II aloft was one consideration.Another may have been air dropping the Shin-

ryu Il in the same manner as the KugishdMXYT Oka. In both cases this may have pre-

serued two of the rocket engines whichwould have been used up had the Shinryu II

taken off from the ground.

In order to combat the B-29, which couldoperate at altitudes up to 10,241m (33,600f1),

the Shinryrl II was to be equipped with a pres-

surised cockpit or, if such a cockpit provedproblematic, the pilot would wear a pressure

suit. For weapons, the Shinryfi II was to bearmed with eight rockets. Attached to theinside of the rear landing skid arrangementwere four tubes, one on top of the other and

angled downwards, which contained the

rockets.There has been some conjecture as to the

mission objective of the Shinryu II. Somesources make the case that the Shinry,'u II wasto be used like the Oka while others come tothe conclusion that the Shinryu Il was to attackarmoured ground targets such as tanks. In

both cases these sources state that the nose ofthe Shinryir II contained an impact fused

explosive warhead and once the rocket arma-

ment was expended, the pilot would crash

the aircraft into his final target using the war-head to deliver the coup de grdce. However,

analysis of the Shinryu II shows that neithermission was likely. The aircraft would have

been far more complex to build than the

Showa Toka or Oka and the Shinryl II wasconstructed for manoeuvrability, high altitudeoperation and the means to land. In addition,using the Shinryu II for shimpu missions

against tanks makes little sense when therewere other simpler and more effective means(both already in service and under develop-ment) to eliminate armour. Perhaps this is a

case of the Jinryu glider's role being applied to

the Shinryr-r II, or an assumption based on the

fact that, like the IJN's other special attack air-

craft such as the Nakajima Kitsuka, KawanishiBaika and Showa Toka, the Shinryu II pos-

sessed no letter/numerical designation. So, by

extension, the ShinryTr II must also have beena special attack weapon. This, of course, is notto say that the pilot could not choose to use

the Shinryr-r II as a shimprl aircraft.As an interceptor, the Shinryu II had a simi-

lar role to the Mitsubishi JSM Syusui and the

Gennan Bachem Ba349 Natter for which the

Japanese were aware of and obtained data

on (although the plans never made it to

Japan). Like the J8M and Ba349 and due tothe limited range afforded by the rocketengines, the Shinryu II would have to be posi-

tioned close to targets that were likely to bebombed. And like the J8M, the Shinryu II

would have used a jettisonable wheeled dollyto take-off while firing a pair of its rocketengines. Unlike the J8M which burned up allof its fuel at once, the Shinryu ll had a secondset of rocket engines which could be used tosustain flight endurance or to increase speedduring the attack. In the same way as theBa349, the Shinryl II would be armed withrocket projectiles, likely fired as a group toaffect a spread pattern, to bring down thebomber target. Finally, akin to the J8M, oncethe fuel and ammunitionwere expended, the

Shinryr II would glide back to its base to berecovered, refuelled and rearmed.

The Shinryl II would never be builtbecause the end of the hostilities in August

1945 terminated any further work on the

design. Likewise, the Jinryu glider wouldnever fly under power. After the failure of the

rocket motors during ground tests, the warcame to a close before more suitable and reli-able motors could be acquired and tested.

Mizuno completed a total of five Jinry0 glid-

ers. As a note, Jinryu is the known name forthe f irst Mizuno glider. For the purposes of thistext, the author used Shinryu II to differentiatethe interceptor from the glider. The kanii is

the same for both spellings but is pronounceddifferently. Both translations of Jinryu and

Shinryl mean 'Divine Dragon'. Shinryl II isalso used in contemporary texts and as such,is used here for recognition purposes.

Whether the interceptor would have carriedthe same name as the glider is unknown.

Mizuno ShinrSr II - data

Contemporaries

Blohm und Vos BV40 (Germany), Zeppelin Fliegende Panzeriaust

(Germany), Heinkel P. I 077 Julia (Germanl'), Junkers EF I 27 Walli

[Germany), Messerschmitt lie l638 (Germant'), BereznyakJsat'ev BI

(Rusia)

Specilications in parenthesis arc for the Shinn'i ll and are estimates onll

Special Atlack Glider (lntercept0I)

0ne

Powerplant Three Toku-Ro Ttpe 1 rockets with a total combined

thrust of 400kg (881 lb) rvith a burn time of l0 seconds (Four Toku-Ro

Tlrpe 2 rockets rvith a total combined thrusl 0f600kg/1,322Ib lvith a burn

time of 30 seconds)

Type

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading

Pou'er loading

7,00m

7,60m

1.80m

l1m:

VA

)i/A

22,91r

21,9ft

5,9ft

I 18.4f1

tN/A)

(N/A)

Weights

Emptv

Loaded

\'laximrrm

NlA

N/A

N/A

(\/A)

(),1/A)

(N/A)

Performance

['lar speed 300knh l86mph

Cruise speed ll0kn'h 68mph

Range 4km 2 miies

Endurance (Shinnuil)1.3minutes

Ceiling 400m l,312lt

l00kg (220Ib) ofexplosive (8 unguided rockets)

Deployment None. A total of five protoptlpe Jinryu gliders were

built br' \'lizuno. The Shinryu II remained a design boatd aircrafi.

106 JnpaxEsr SEcnnr PRo;ecrs: ExpsnrueNrnr- AIncRapr oF rHE IJA AND IJN 1939-1945

IlrpEnrll JapnNsse Nevv 107

Nakajima Fugaku

Japan shared a fundamental flaw with Ger-

many in regards to not developing a bombercapable of long range missions. The lack ofthis capability is considered by some to be apivotal nail in the coffins of each country dur-ing the war. In both cases, efforts to developsuch a bomber came too late to affect the out-

come of the conflict. Although the Japanese

had considered the need for such a bomberat the outset of hostilities - as had the Ger-

mans with the disastrous Heinkel He177

Greif -verylittle happened until the need wasdire, and by then the noose was tight, chok-ing any hope for putting a long range bomberinto service.

The main cause of this apathywas the early

success in the Pacific theatre where the shortand medium range bombers then in use bythe Japanese were adequate to fulfil the

needs of the IJA and IJN. With the entry of the

United States into the war a formidable prob-lem arose. Geography put the militarymachine of the US far out of reach of Japan.

When the tide of war turned against theJapanese, it was soon realised that somemeans to attack the US mainland had to beacquired, not only to destroy the war industryof America but to ravage the civilian popula-tion centres to reduce morale and bring the

war to the US doorstep. In consequence, the

US would have to allocate or divert resources

to increase the defence of the homelandwhich would affect the war on other fronts.

As historywas to show, the Japanese did suc-

ceed in launching attacks against America,but only in the form of the Fu-Go balloonbombs and isolated attacks on the west coast

from submarinelaunched float planes. None

had much of an effect.There were some early attempts to pro-

duce a long range bomber - for example, the

Mitsubishi G7M1 Taizan (a 16-shi proiect) -plus designs that were actually built such as

the Nakajima G5N Shinzan and NakajimaG8N Renzan. The Shinzan was not a success

and the Renzan failed to reach operational

selice as a combat aircraft, let alone reachAmerica and return.

It was to be Nakajima who would attempt toprovide a strategic long range bomber capableof bringing the war to America. The manbehind the project was Chikuhei Nakaiima,

chairman and engineer of Nakajima HikdkiK.K. Motivated by his fears over the inability ofthe Japanese to reach and destroy US indus-

trial capacity, Chikuhei tried to convince the

IJN and the IJA of the need for a strategicbomber. However, officials from both services

refused to consider his ideas. Thus, withoutofficial sanction or request, Chikuhei invested

a portion of Nakajima's resources to draft

designs for a bomber that could take-off fromJapanese bases, cross the Pacific, attack tar-gets on the West Coast of America and returnto either their original bases or elsewhere inJapanese orAxis held territory. Nakaiima gave

the design work the name 'Project Z'.On 29 January 1943, Nakajima began the

ta-sk of assembling drafts and studies for the

108 .lApANEsE SEcRET PRolEcrs: ExpERItteNrnl AIRcnapr op rHE IJA arln IJN 1939-1945

design of the bomber, along with reportswhich studied the feasibility and problems ofproduction. On the completion of this stage inApril 1943, he again pitched the concept toboth the IJA and the IJN. This time, neitherselice turned Nakajima away. However,despite the information Nakajima had assem-bled for the proposed bomber, and despiteboth services now accepting the need forsuch an aircraft, the IJA and the IJN also pro-duced their own ideas. Not surprisingly, thehvo services had differing opinions on therequirements for the bomber. The IJA desireda tlpe that could operate at 9,998m (32,800ft)

and carry a heavy defensive armament. Bycontrast, the IJN wanted a bomber capable offl-v'.ing at a height of 14,996m (49,200f1), an alti-tude where interception would be minimaland thereby allowed a lighter defensive\veapon load to be carried. Furthermore, theIJN wanted the bomber to take-off fromJapan, bomb any target within the US, thenutilise bases in Germany or German held ter-ritory to land, as opposed to making a roundtrip.

Though there were a number of variationsof the aircraft during the Project Z develop-ment, three basic designs of what becamethe Fugaku emerged. The project presentedb1,' the IJA used a 'tail sitter' undercarriage,featured dual vertical stabilisers and boresome resemblance to German designs. It alsohad a rounded off nose similar to the BoeingB-29 Superfortress and Messerschmitt Me 264'Amerika' bomber. The IJN's proposeddesign used a tricycle landing gear arrange-ment and rounded nose but utilised a singlevertical stabiliser. Nakajima's proposal keptthe single vertical stabiliser but had a steppednose much like that used on the G5N Shinzann'hich the company had previously workedon.

By June 1943, Nakajima had received plansfrom the IJA and IJN, reviewed them andbegun work on drafting a final design. To con-tinue the research and further developmentand study the Project Z aircraft, the Army and\avy Aviation Technical Committee wasformed on 9 August 1943. The IJA delegationn'as headed by Captain And6. Later in August,Chikuhei Nakajima prepared a thesis entitled'Strategy for Ultimate Victory'. Chikuhei usedhis personal clout to make sure his documentreached not only IJA and IJN officials, but alsopoliticians and even Prime Minister HidekiT0j0. His thesis was laid out in six chaptersand contained Chikuhei's plan for defeatingthe US as well as defending Japan. The keycomponent was the Project Z bomber whichhe proposed could be used to destroy US air-fields as a means to deny the US the ability tolaunch raids against Japan. This suggestion

IrrpEnru Japanrse Navv

was in part due to his belief that Japanese airforces were not strong enough to repel a

bombing raid. Another facet of the thesis wasthe use of the bomber to attack the US warindustry. Without materials and oil, the US

could not produce aircraft, tanks and otherweapons. More importantly, he added, theJapanese should use the bomber to destroythe Soviet military industry as a means to sup-port Germany. This implied that Nakajimacould provide Germanywith such long rangebombers.

The Project Z bomber would employ an allmetal structure with the wings mounted inthe mid-fuselage position. The plane wasenvisioned to be powered by the NakajimaHa-54, 36-cylinder radial engine, also knownas the D.BH. The Ha-54 was, in fact, two Ha-441 8-cylinder radials paired together. It was pro-jected that the Ha-54 engine could produceup to 5,000hp and that six of these would besufficient to propel the bomber to a generousmarimum speed of 679km/h (422mph). Eachengine would drive two contra-rotating,three-bladed propellers with a 4.5m (14.7f1)

diameter. The Ha-54 engine, however, wouldnot be ready for some time (and as eventsturned out, by war's end it was still only a pro-totype engine and problems with cooling thepower unit through the use of a ducted cowl-ing were never solved). Therefore, Nakajimahad to settle for the experimental NKllA(Ha-53) which, while also in development,was expected to be ready for trials. The drar.r.back was that the NKI 1A was expected tomuster only 2,500hp and this would certainlyhave lowered the performance estimates.The introduction of the NKl1A meant that arevision of the Project Z airframe becamenecessary.

The bomber's ceiling was estimated to be1 5,000m (49,212tt) and it was believed that ahealy defensive armament was not neces-sary as the high altitude would offer protec-tion from fighter opposition. To a lesser extentthe projected speed would also reduce vul-nerability. Consequently, the bomber wouldcarry at least four Type 99 20mm cannons, butcontemporary illustrations of the bomberoften show a much heavier armament. Thismay be a result of having to settle for the lesspowerful NK11A and any speed/altitudeadvantage would have been lost, so anincreased weapon load would have beennecessary to protect the aircraft. Typically,illustrations show two cannon mounted inthe tail, two in the nose, two twin-cannon tur-rets placed in the front and rear of the fuse-lage top and at least one belly turret.Variations included waist gunner stations. Fora normal bomb load, the bomber wasexpected to carryup to 20,000kg (44,0921b) of

Nakajima Fugaku - data

Contemporaries

Conrair B-36 Peacemaker IUS), Convair XC-99 (l,S), I{essenchmitt

['1e264 and N'le264B (Oermany), Junkers ju390 (Germany), Junkers EFl00

(Germany), Nlesserschmitt ['le P 08,01 (Germany), Tupolev Tu-4 (NATO

codenameBui/) (Russia), Tupolev Tu-85 (NATO codename Barge)

(Russia), Tupolev Tu-70 (Russia), Vickers.Armstrong Victory Bomber (UK)

Specifications in parenthesesrefer to the Fugahu specifical\'. All other

specificalionsrefer lo the primon Nahajina Project Z design.

Long range slrategic bomber

Six to ten Geven to eight)

Powerplant Six Nakajima Ha-54 36-cvlinder, air-cooled radials

developing 5.000hp at engine start, each driving two alternaling stroke,

contra-rolating three bladed propellers of 4.5m (i4.7ft) diameter/Six

Nakajima NKI lA {Ha-531 18-cllinder, air-cooled radials developins

2,500hp at engine start and each driving a altemating stroke, four-bladed

propeller ol 4,8m (l 5.7ft) diameter

Tlpe

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading,

normal

Wing loading,

loaded

Power loading,

normal

Porver loading,

loaded

Aspect Ratio

64.98m 213.2f1

(Fugaku) 62.97m 206.6ft

44.98m 147,6f1

(Fugaku) 39.98m 13l,2ft

8.77m 28.8ft

(Fugaku) 8.77m 28.8ft

352.01m: 3,766.8ft'

(Fugaku) 330.00m' 3,552ft'

348,60k9m' 71,4lb/ft'

(Fugaku) 126,91kg/n: 261bilt'

456.99k9/m' 93.61b/fl:

(Fugaku)211.89k9m' 43.4lb/fl'

5 44kgihP 12 lbih'(Fugaku) 3,76kghp 8.3lbihp

7.2lks/hp l5.9lb1hp

(Fusaku) 6.30ks/hp l3.glblhp

tz.t (NlA)

Weights

Emptv

Loaded

N'lar loaded

65.000kg 143,3001b

(Fugaku) 33,800kg 74.5161b

122,000k9 268.9631b

(Fugaku) 42,000k9 92,5941b

160,000kg 352,7391b

(Fugaku) 70,000k9 154,3231b

Performance

Mex speed

Take-olf run

Range

il'lar range

Ceiling

679krn'h 422mph

at 10,000m at 32,808f1

i79knt' 184mph

(Fugaku) at 10,000m a132,808ft

(Fugaku) 1,020m 3,347ft

16,499km 10,252 miles

(Fugaku)16,499km 10,252miles

17,999km ll,l84miles

(Fugaku)19,400km 12,054miles

15,000m 49,21211

(Fueaku) i5,000m 49p12fi

Armament

Four Tlpe 99 2Omm cannons (up to l2 cannons depending on the

source) and a marimum bomb pa,vload 0f20,000k9/44,092Ib

Deployrnent

None. The 'Project Z' and Fugaku aircralt existed onlv as paper designs.

109

bombs, but in the case of anti-shipping mis-sions, torpedoes could be carried (see

below). For attacks on the United States, thebomber would carry only up to 5,000kg(1 1,023Ib) of bombs.

As work continued on the Project Z, planswere made to assemble and house thebomber's production line. By the fall of 1943,

these plans had been completed and con-struction of the new facility had begun. ByJanuary 1944, the Project Z moniker wasdropped and changed to the Fugaku whichmeans'Mount Fuji'.

As it was, more pressing demands onNakajima resulted in less and less work beingdone on the Fugaku. To compound the prob-lem, by the time the design was nearing com-pletion, Japan was on the defensive andchances of producing the Fugaku, let aloneusing it to attackAmerica, were about nil. TheIJA believed that there was no probability ofthe Fugaku being built and therefore aban-doned the project, leaving the IJN as the soleremaining party involved. Even the Gunjushd(the Ministry of Munitions) felt the Fugakuwas impossible to realise and orderedKawanishi to design a new long rangebomber. Unfortunately, the Gunjusho failedto inform the IJA, IJN and Nakajima about theKawanishi bomber, which was known as theTB. When the new bomber project was dis-covered, a hail of protests and argumentserupted ihat hampered not only the develop-ment of the Fugaku but all long range bomberprojects including the TB r,vhich was sooncancelled.

However, it was the fall of Saipan in 1944

that sealed the Fugaku's fate. The Japaneseair forces no longer had need of a super longrange bomber and demanded more perti-nent aircraft to protect the mainland. As such,all work on the Fugaku was stopped and theplans, calculations and drafts were shelved.Work on the production facility was haltedprior to completion and left unfinished. Withthe Japanese surrender, all documentation

for the Fugaku was to be destroyed to preventthe information being handed over to theAllies. Papers on the Fugaku that survive tothis day, including a number of drafts for var-ious Project Z/Fugaku proposals, were mis-laid or kept for safe-keeping by individuals.Since the war it has been claimed that theMisawa Air Base would have been used byFugaku bombers to launch raids against theUS. While Misawa was used by the IJA andoperational IJA bombers flew from this facil-ity, there has been no definitive evidence tosupport or refute Misawa being considered as

a Fugaku base.Bombing was not the only mission that was

envisioned for the Fugaku and during the Pro-ject Z brainstorming three other conceptsarose and later formed part of Chikuhei's the-sis. The first was an attack design that had 400

Type 97 7.7mm machine guns crammed intothe aircraft. The front and the back of thebomber would accommodate 40 machineguns arranged in ten rows. The intention wasto rain thousands of rounds of bullets downon to enemy ships with the theory that aswath of destruction 45m (148ft) wide and1Okm (6.2 miles) long could be achieved by15 Fugaku aircraft. Once the decks of theseships were swept of personnel, nine Fugakubombers, each with twenty 907kg (2,000Ib)

bombs or torpedoes, would deliver the coupde grAce, covering a path 200m (656ft) wideand lkm (0.62 miles) in length with highexplosive.

Another version had the Fugaku loadedwith 96 Twe 99 20mm cannons. The frontand the back of the aircraft would contain 12

cannons arranged in eight rows whileanother 36 cannons lvere fitted on each sideof the aircraft. This particular variant was totarget enemybombers flying missions againstJapan and would use hidden basesuntouched by the Japanese airfield bombingcampaign. By flying over the enemy bomberformation and unleashing a withering fusil-lade of cannon fire, it was speculated that ten

of the cannon equipped Fugaku could bringdown 100 bombers, the area covered by thecannons from one plane being 2.5m (8.2ft)

and 3km (1.86 miles) long. A system ofground radar stations would give advancewarning of the incoming enemy bomberforce, allowing time for the Fugaku to inter-cept and destroy the bombers before theyreached Japan. This was all very impressiveon paper but had it been put into practice theresults were likely to have been less than stel-lar, especially when considering the failure ofthe Mitsubishi G6M1 heary escort fighter (aG4M converted into a gunship to providecover for bomber formations). Finally, theFugaku was considered as a transport whichwould have provided a significant healy liftcapability. It was estimated that one Fugakutransport would be able to carry 300 soldierswith full equipment, about equal to oneinfantry rifle company with a heavy weaponplatoon. Chikuhei envisioned a grandscheme of a raid against America where fourhundred transports would deposit 120,000

men (equivalent to a Japanese Army, whichequates to a US and British Corps) on US soilto take over the Seattle-Tacoma airportlocated in Washington. After landing thetroops would move overland to attack anddestroy Boeing's B-29 producing Renton Fac-

tory in Renton before returning to Japan.There is no evidence to suggest any of

these concepts made it to the final Fugakudesigns. However, if any of the three ideaswere supported, a transport may have toppedthe list for possible consideration given thelate war need for aircraft capable of bringingraw materials into Japan to feed the warindustry that was slowly being starved. As anote, although the designations G10N andG 10N I have been used in print for this aircraftfor many years, there has been no confirma-tion in historical sources that confirms thiswas the case.

I

z

110 JApAr'JESE Srcnpr PRo;Ecrs: ExpERmenr,ql ArRcRapr or rue IJA nNo IJN 1939-1945

Ioz-

lrrpnnrx- .lnplruEsE Navv l1l

In the spring of 1938, the IJN issued a 13-shi

specification for a long range fighter. Thiscame about as a result of combat experiencein China that showed that Japanese fightersdid not have the range to escort bombers onmissions deep into Chinese territory, theresult of which were high losses. What Naka-jima produced to answer the specificationwould have been a complete failure had it notbeen for one redeeming feature.

The l3-shi specification was a very strictone with a number of very demanding crite-ria. Nakajima's Katsuji Nakamura would pro-duce the initial prototype. It was anaerodynamically clean 3-seat monoplanewith low mounted wings. Each wing houseda Nakajima Sakae radial, developing 1 ,130hp.However, one wing was fitted with a Sakae 21

engine, the otherwith the Sakae 22, and theirpropellers rotated in opposite directions toreduce torque. To complement the nosearmament, twin remote controlled barbettes,each with two 7.7mm Type 97 machine guns,were placed behind the pilot's cockpit. Des-

ignated the JlNl, the first two protob,peswere delivered and put under test. A myriadof problems were noted - the plane was over-weight, the novel propeller arrangementcaused numerous difficulties, the hydraulicsystem was too complex, the barbettes weretoo difficult to aim and the entire arrange-mentwas too hear,y. To top it all off, manoeu-vrabilitywas poor and all the JlNl had goingfor it was its range.

Rejected as a hear,y fighter, the JIN wasgiven new lease of life as a reconnaissanceaircraft. Nakajima stripped the aeroplane ofits weapons and the barbettes, cut the fuelcapacity (which, in part, was made up byusing drop tanks) and replaced the Sakae 22

engine with another Sakae 21 powerplant.The armament was a single, rear firingl2.7mmType 2 machine gun to be was usedby the radio operator. Now called the J 1 N 1 -C,

following successful trials the aircraftreceived approval and entered service withreconnaissance units from August 1942. Onencountering it in combat, the Allies code-named the plane lrulng, thinking it was afighter. The IJN renamed the plane JlNl-R,equipping some examples with a turretmounting a 20mm Type 99 Model 1 cannon.

In early 1943, CommanderYasuna Kozono,who led the 251st Kdkutai operating fromVunakanau Airfield in Rabaul, Papua NewGuinea, believed that the J 1 N 1 -C would makean excellent night fighter. Mechanicsreplaced the observer's station and installedtwo 20mm Type 99 cannons that fired

Nakajima JIN Gekkd

upward and forward at a 30' angle and twoadditional cannons firing downward and for-ward at a similar angle. Called the J 1 N 1 -C Kai,

the field modification proved a success andwith that success, the IJN became interested.

In short order, Nakajima was instructed bythe IJN to produce a dedicated night fighterversion of the J1N. ByAugust 1943, the assem-bly of the first model, the JlN1-S Gekko(meaning 'Moonlight'), had begun at Naka-jima's Koizumi plant. The main changes sawthe glazing over the crew compartmentreduced and the step removed. The ringexhaust collector was also removed and theengines used individual exhaust stacks. Inaddition, it was realised that the downwardfiring cannons were ineffective and in theJ I N 1-Sa were removed. Both the J 1 N 1 -S andJ1N1-Sa were sometimes fitted with a centi-metric radar in the front of the aircraft, theexternal antenna for the set being situated onthe tip of the nose. Others had a searchlight inthe nose while a number lacked the radarand searchlight to be replaced by a single for-ward-firing 20mm Type 99 cannon.

In combat, the Gekkd proved satisfactoryagainst the Consolidated B-24 Liberator, butagainst the faster Boeing B-29 Superfortresswas hard pressed to make a single attack.Therefore, it should not be surprising that theJIN was considered as a candidate to beequipped with two turbojets. Successful as areconnaissance platform as well as a nightfighter, replacing the radial engines with tur-bojets would have provided the JIN with a

superior speed that would have served it wellin either role. A contemporary illustration ofthe turbojet equipped JI N shows the fuselageof aJl N 1-Sa. The illustration lacks the upwardfiring cannon and radar which suggests it wasequipped with the nose mounted cannon asits armament. Perhaps it may have worked inconjunction with radar and/or searchlightequipped JlNl-S and J1N1-Sa during combatmissions, or it may have been considered as

a fast special attacker fitted with two 551 lbbombs (as surviving J1N aircraft were at theend of the war). The wings seem to havebeen unaltered outside of the required mod-ifications to fit the nacelles for the turbojets.As to what iet engines were to be introducedis not known. The Klgish6 Ne 20 was cer-tainly a candidate as was the NakajimaNe 230. The adaptation of the Jl N to jet powerlvould likely have been an easier task thanthat faced by Kugisho in adapting the PlYlGinga into the turbojet bomber Tenga.

Exactly when the proposal to modify theJIN to a turbojet aircraft was made is

unknown. What is known is that it did notprogress past the drafting board.

Nakajima JIN Gekko - data

Contemporaries

Curtiss XP-87 Blackhank (US), l,lesserschmitt P.1099 (Germany)

No exact specifications ate hnoun fot the turbojet pouered I I N .

The specifications aiuen belou are for the JlNl-5.

T1pe Night Fighier

Crerv Trvo

Powerplant

Two Nakajinia ),JKlF Sakae 21 l4-cylinder, air-cooled radial, each rated

at l,J30hp for take-off, l,l00hp at 2,850m (9,350it) and 980hp at 6,000m

(19,685ft), driving a three-bladed, c0nstant speed metal propeller

Dimensions

Span

Leogth

Height

Wing area

Wing loading

Poner loading

16.97m 55.7fi

12.74m 4l.8ft

4,54m l4,9ft

40.00m' 430.;fl:

175,27k{n' 35.9lb/ft'

3.62k9/trp 8lb/hp

Weights

Empt"v

Loaded

\'larimum

t0,670Ib

i5,454Ib

I8,043Ib

4,840k9

7,01Okg

8,l84kg

Performance

Speed

Cruise speed

Climb

Range

['1ar range

Ceiling

507krrt,'h

at 5,840m

3nkn/h

at 4,000m

3l5mph

at 19,160it

207mph

at 13. I 25ft

9 min 35 sec to 5,000m (16,405ft)

2,544km 1,581 miles

3,779km 2,348miles

9.330m 30,610ft

fumament

Tlvo upnard firing 20mm Trpe 99 cannons and hvo dolr,nlard firing

2Omm Type 99 cannons installed in the luselage

Deployment

None. The turbojet porvered J1 N remained a paper project

112 Jnperuese SEcnEr PRoJecrs: ExpnRrrvrsNrnL ArncRerr oF rHE IJA AND IJN 1939-1945

b-$s-U<lN\\

{eI -.'tt:i;!

f*p

m'

,il

fl.s:,1,

,/

113lrrpEnral JnpnrriEsE Navv

oIoz-2

Even though the genesis of the turbojet beganlong before World War 2, it would take the warto accelerate the development of this newpowerplant to the point that by the close of hos-

tilities jet aircraft had been blooded in battle.

Germany can, by some, be considered theleader in turbojet technology during the war,

but the US and Britain were not far behind.

Japan, too, was not idle in producing its ownturbojet but it would take German knowledgeto give their industries a boost. One such

results was was an historic aircraft in the

annals of Japanese aviation history: the Naka-jima Kitsuka.

Because the Kitsuka (which in Japanese

means 'Wild Orange Blossom') was probablythe most important Japanese aircraft to use ajet engine as its powerplant, it seems apt toprovide a general overview of Japanese turbo-jet development in this section. The first axial-

flow turbojet was patented in 1921 by

Frenchman Ma.xime Guillaume. However, the

technology of his day was not enough io realise

a working model. In 1930, Englishman Frank

Whittle designed a turbojet using a centrifugal

Nakajima Kitsuka

compressor and, despite relatively little inter-est being shor,rn in it, he patented his concept.In 1933, German Hans von Ohain designed a

turbojet similar to Whittle's bui it would not be

until 1936 that Ernst Heinkel took an interest inthe engine and hired von Ohain to continue his

work. By March 1937, this resulted in theHeinkel HeS 1, the first German jet enginealthough in fact a hydrogen demonstrator. Thefollowing month Whittle tested his first jet

engine, the WU orWhittle Unit.Around this time, Rear Admiral Koichi Hana-

jima became aware of Whittle's work as well as

that of Secondo Campini, an Italian who began

work on a thermojet and an aircraft to use it: the

Campini Caproni N.1 in 1934. This rekindled his

interest in jet propulsion and using his position

as head of the engine division of the Dailchi Kai-

gun Koku Gijutsu-sho, saw to it ihat studies were

conducted in such engines. Hanajima reached

out to the Tdky6 Imperial University and Mit-

subishi Juk6gyd K.K. and together all manner ofrocket and iet engines were investigated such as

ramjets. To Hanajima's disappointment, littleofficiai interest was generated from the results.

1938 saw German firm BMW begin theirresearch into turboiets and the Heinkel He 178

Vl prototype was built to test the HeS 3 turbo-jet that was being developed from the earlierHeS 1. In late 1938, Messerschmitt started workon what would become the world's first ietfighter to enter squadron seruice, the Me 262. In

Japan, and despite the lack of interest beingshown in jet propulsion, Captain TokiyasuTanegashima was appointed as the head of theEngine Test and Field Support Shop of Kt1gish6.

He was issued with a meager sum to fund jet

engine research although, with the assistance

of Professor Fukusaburo Numachi, he wouldinitially focus his efforts on turboprops. Both

men were able to source the Ishikawaiima-Shibaura Turbine Company and Ebara Seizo

K.K. to help build a number of test engines that

used compressors and gas turbines, but these

labours did not bear fruit.By 1939, BMW had tested its first axial-flow

turboiet design and on 27 August of that year

the He 178 Vl made its first flight, the first tur-

bojet powered aircraft to fly. In February 1940,

the British Air Ministry ordered two examples

114 JapaxesE SEcRsr PRo;Ec'r's: ExpsRruENter- AtRcRarr oF rHE IJA ar"rl IJN 1939-1945

ofthe E.28l39 research aircraft from the GlosterAircraft Company to serve as testbed aircraftfor Whittle's engines. 1940 also saw the ltalianN.l fly forthe first time and Heinkel began glid-

ing tests of the He 280 jet fighter prototype as itrvaited for its two HeS 8 turbojets now underdevelopment (the He 280 did not enter pro-duction). November would see Junkers testthe Jumo 004 turbojet and Gloster's jet fighterproposal, the Meteor, was ordered in February1941. Also in November, Lockheed com-menced work on the L-1000 axial-flow turbo-iet, the first American jet. Finally, in December,[/hittle's W.lX turbojet, a flight ready engine,n'as tested for the first time.

Japan though, was not idle in 1940. Early inthe year, Tanegashima, with the help of the Mit-sui Seiki Kogyo K.K., created a free piston com-pressor for a gas turbine based on a Junkersdesign, but it was not a success as a means foraircraft propulsion. Another attempt was triedb1'a different department. Under the leader-ship of Lieutenant Commander Osamu\agano, head of the Kugish6 aircraft enginediv'ision, and Masanori Miyata, who led theKugishd electric parts section, built a tiny freepiston compressor gas turbine, generating onetenth of a horsepower at 1 2,000rpm that drovea magneto that lit a lamp. Despite this measureof success, apathy on the part of the IJN con-tinued to stymie progress. Tanegashima soonrealised that the Japanese industry was notcapable of constructing a free piston engineand switched his studies to axial flow jets.

On 1 5 May 1941 , the Gloster 8.28/39 flew forthe first time, but previously in April, Heinkel'sHe 280 Vl had flown under jet power on itsmaiden flight, the first jet fighter to fly. 1942 sawthe Junkers Jumo 004 under test while BMWfocused efforts on the BMW003 Sturm. Heinkeln'as instructed to concentrate on developingthe HeS 011, a turbojet that was to power thesecond generation of German jets. On l8 July,the Messerschmitt Me 262 flew under turbojetporver, becoming the second jet fighter to fly,

and on 2 October, the American Bell XP-59

.dracomet jet fighter made its maiden flight. By

this time, Japanese engineers and scientistshad learned of the flight of the He 1 78 as proofthat an aircraft powered by a jet engine wasfeasible. This was just the boost the flagging.lapanese jet engine research desperatelyneeded.

As a result two different paths were takenu'ith renewed vigour. The first employed theprinciple of the thermojet (as used by SecondoCampini) and was called the Tsu-l 1 . While thisengine was to be selected for use in theKugisho Oka Model 22, iI was found to beunsuited as a powerplant for a iet aircraft. Thesecond route, that of a pure jet engine, waspursued further. Kugish6's Vice Admiral Misao

IrrpEnrnl JnpeNsse Nevy

Wada was the man who oversaw the develop-ment of a turbojet and the first result was the

TR-l0. This had a single stage, centrifugal com-pressor with a single stage turbine and was, inessence, built by adapting a turbosuper-charger. The engine was constructed by Ebara

Seizo K.K. When the TR-I0 was first tested inthe summer of 1943 its performance did notmeet expectations. The TR-10 was renamedthe Ne 10 and the engine was further devel-oped by adding four axial stages in front of theengine inlet. This reduced the load on the cen-trifugal compressor, lowered the engine RPM

and produced more thrust. The revised jetengine was designated the Ne 12. The problemwith the Ne 12, however, was its great weightand so steps were taken to lighten the engine,which resulted in the Ne 128.

1944 was an ominous year for Japan. Whenthe Mariana Islands of Saipan and Tinian werewrestled from the Japanese by US forces in Julyand August, Japan found herself well withinstriking distance of the Boeing B-29 Super-

fortresses. Prior to this, B-29 raids had to flyfrom remote bases in China and India and so

the bombing of Japanese targets was relativelyrare. Staging from Saipan and Tinian, B-29s

were far closer, could be more active and theJapanese were only too aware of this. In addi-tion, it was surmised that it would only be amatter of time before the main Japanese

islands were targeted for invasion. In August1944, the Kaigun Koku Hombu called for ameeting to discuss changes in air strategy to

combat the air and land threat as well as toconsider the aircraft that would be used. The

Kaigun Koku Hombu invited aircraft designersfrom both Nakajima and Kawanishi to attendand the outcome of this meeting was the pro-posal for three classes of aircraft termedKokoku Heiki (one literal translation being'Empire Weapon'). The first class, or KdkokuHeiki No.1, was the adaptation of cunent air-

craft to accept a 800kg (1,7601b) bomb withwhich their pilots would undertake shimplmissions and target enemy invasion ships. Ifthe bomb overloaded the carrying capacity ofthe aircraft, then RATO (Rocket Assisted Take-Off) units would be used to get them airborne.Kokoku Heiki No.3 was to be a conventional,radial engine aircraft designed by Kawanishi as

the Tokkoki, which would be used for shimplmissions, but this proiect was soon abandoned(perhaps because the IJN was to build the sim-ilar Nakaiima Ki-115 as the Showa Toka).It would be Kokoku Heiki No.2 which providedthe seed for the Nakajima Kitsuka. This'Empire Weapon' was to be an aircraft thatused the Tsu- 1 I and, when available, the Ne I 2

turbojet.However, three months prior to the meeting,

efforts were underway to obtain the Me 262

from Germany. In May 1944, the Japanese

negotiated for the manufacturing rights to theMe 262 and the Germans initially agreed to therelease. However, the deal was not concludeddue to the large number of modifications thatthe design was found to require after its flighttesting. It was not until July 1944 that orderswere given to provide the Japanese with blue-prints of the Me 262 fighter and the JunkersJumo 004 and BMW 003 turboiets.

On 22 July 1944, Reichsmarschall HermannGoring authorised the licensing of the Me 262

to Japan and the delivery of one sample air-craft. However, the Japanese submarine I-29

had left Lorient, France, on 16 April with a sam-ple Junkers Jumo 004 turbojet and plans for theMe 262 and BMW 003 turbojet among its cargo.Also aboard the submarine was TechnicalCommander Eiichi Iwaya who carried on hisperson a portion of the documentation on theGerman fighter and turbojets. By 14 July, theI-29 had arived in Singapore. Iwaya, seeking toreach Japan as soon as possible, disembarkedfrom I-29 and took only aportion of the Germandocumentation. From Singapore, Iwaya fl ew toTokyo. On 26 July, Allied code intercepts pin-pointed the location of I-29 and the USS Solo-/lsh sent her to the bottom near the BalintangChannel in the Luzon Strait, taking the preciouscargo with her.

When Iwaya arrived in Japan, all he pos-sessed of the German files with regards to theMe 262 and turbojets was a single copy of across-section of the BMW 003A turbojet. The

subsequent news of the loss of I-29 was acrushing blow, but not a fatal one by anymeans. In studlng the BMW 0034 document,the Japanese found it to be of a similar designto the Ne 12 but instead of the centrifugal com-pressor the German engine used an eight stage

axial-flow compressor. lt was adjudged thatthis method was superior to the Ne l2 and as

such, efforts should be concentrated on build-ing the Japanese equivalent to the BMW 003A.

Despite the decision against it, work on theNe 128 continued. Four companies wereinvolved in the development of the new turbo-jet. Each was to be provided with a copy of theBMW 003A cross-section and other availabledata and to build their own versions. Ishikawa-jima-Shibaura Turbine Company was todevelop the Ne 130, Nakajima Hikoki K.K. theNe 230, Mitsubishi JnkOgyO K.K. the Ne 330, andKlgishd would move forwards with the Ne 20.

Following the August conference with theKaigun Koku Hombu, Ken'ichi Matsumura,chief designer for Nakajima and with the assis-

tance of Kazuo Ono, produced a number ofconcept drawings for the Kokoku Heiki No.2.

Within Nakajima, the new aircraft was given

the codename Maru-Ten. On 14 September1944, IJN representatives met with Nakajima at

115

their Koizumi plant to discuss the concepts

which had been put forward. The design that

stood out was based on a description of the

Me 262 as provided by Technical CommanderEiichi Iwaya who, while in Germany, was able

to view and study the German jet. Thus, Mat-

sumura's drawing bore an outward resem-

blance to the Me262. After reviewing the

concept, the design was approved as the

Kokoku Heiki No.2. In keeping with the shimpumission of the aircraft, the initial design had no

landing gear and was to be launched from cat-

apult ramps, boosted with MTO units. The cal-

culated range was a mere 204km (127 miles)due to the designated engine, the Ne 12, whichburned fuel at a rapid rate. At sea level the esti-

mated speed was 639km/h (397mph). A single

bomb fixed to the aircraft was the only arma-

ment. Another feature was the inclusion offolding wings to allow the aircraft to be hiddenin caves and tunnels and protected frombombing attacks.

On 8 October, Kugisho ordered Kazuo

Yoshida, plant director for Nakaiima, to have a

wooden mock-up of the aircraft completedand ready for inspection by the end of the

month. In addition Nakaiima was told to have

the initial structural plans finished by the same

date. This was ordered so that production ofthe aircraft could begin without delay. Unforiu-

nately, delays would be a major problem. The

IJN promised that the Ne 12 would be ready fortesting by November 1944 and in short orderthereafter, production engines would be avail-

able. Based on this assumption, Nakajima was

to construct thirty aeroplanes by the end ofDecember 1944. Because of the rush to pro-

duce the aircraft, a myriad of problems arose

with the design which necessitated changes. Amajor issue was the lack of critical war materi-

als which required the use of substitutes and

brought additional delays. To compound theproblem, Nakajima was concerned that the

Ne 128 would not be ready despite the IJN's

promises.Meanwhile, Kugisho proceeded with the

Ne 20. The engineers were forced to use alloys

which were not to the standards of the German

engine and would be a source of problems dur-

ing testing. The design of the Ne 20 was smaller

than the BMW 003A but it retained the com-

bustion chamber shape of the German engine.

While it used the same size of burner as the

BMW 003A, it only used twelve instead of six-

teen due to the smaller size. Kugish6 woulddraft and refine the design of the Ne 20 through

December.On 9 December 1944, the IJN called a meet-

ing to discuss the progress and outlook of the

Kokoku Heiki No.2. Based on the problems

Nakajima were having with the aircraft, not to

mention the doubts about the Ne 12, the pro-

duction schedule was revised. Nakaiima wererequested to produce the first prototype by

February 1945 for use in static iesting. It was

also during this meeting that the aircraft's spec-

ifications underwent a revision. Instead of afixed bomb, the bomb could now be released

by the pilot. The role of the aircraft was also

changed. No longer was it to be used for ashimprl mission but instead for close air sup-

port, the aircraft acting as a fast attack bomber.

As a consequence ofthese changes, the design

had to incorporate a landing gear. The IJN

issued its specifications for the new iet, whichwas now called the Kitsuka, and the docu-

ments requested:Span: no more than 5.3m (17.3ft) with the wings

folded

Length: no more than 9.5m (31.1ft)

Height: no more than 3.lm (10.1ft)

Powerplant: Two Ne 12 jet engines

Maximum Speed: 513km/h (3l9mph) with

500kg (1,102Ib) bomb

Range: 204km (127 miles) with a 500kg

(l,l02lb) bomb or 278km (173 miles) with a

250kg (551 lb) bomb

Landing Speed: 148km/h (92mph)

Take-offRun: 350m (i,148ft) using two 450kg

(992Ib) RATO bottles

Manoeuwability: The aircraft had to be highly

manoeuwable, have a short turn radius and

be stable at speed to facilitate target tracking

Protectioni Shatter proof glass for the canopy.

Front windscreen to have 70mm of bullet

proof glass. 12mm of steel armour plate

below and behind the pilot. Fuel tanks to be

22mm sandwich types

Basic lnstrumentation: Tachometer, altimeter,

artificial horizon, airspeed indicator, Model O

Tlpe 1 flur gate compass, fuel pressure

gauge, oil pressure gauge, oil temperature

gauge, tail pipe temperature gauge and a pitot

tube electric heater

Basic Equipment: Type O parachute, automatic

fire extinguisher, Tipe 3 dry battery, Tlpe 3

radio receiver, Tlpe I life raft and a reserve

weight of 30kg (66.1 lb)

1945 would open with more misfortune for the

Japanese war machine. Japanese troops werepushed out of Burma from 5 January and B-29s

would bomb Tokyo the next day. Two days ear-

lier, Matsumura and Ono, along with others

involved in the Kitsuka proiect, discussed thepossibility of using the Ne 20 turbojet in place ofthe Ne 12. ln the debate, some suggested that

the Ne 20 was not as far in development than

the Ne 12 and would delay progress if used. On

the other hand, some argued that the Ne12

was not achieving significant results. In the

end, the consensus was that the Ne 12 should

remain as the powelplant only because it was

projected to be ready before the Ne 20.

On 28 January 1945, the wooden mock-up ofthe Kitsuka was finally ready for inspection at

Nakajima's Koizumi plant. Vice Admiral Misao

Wada and his staff visited the plant and

inspected the mock-up with both Matsumuraand Ono in attendance. It rn'as made clear tothe Krlgisho inspectors that the Kitsuka was avery simple aircraft that could be constructedin 7,500 man-hours. By comparison, it took15,000 man-hours to build a Mitsubishi A6M

Reisen. Following the inspection, Nakaiima

was told to make two slight adiustments to the

Kitsuka. The first involved the windscreen.

Originally, the front windscreen was roundedbut now it was desired that it should be flatpanelled. This change may have been sug-

gested to allow for the future installation of areflector gun sight because such a sight

requires flat panels to avoid sighting problems

due to canopydistortion. The second alterationwas to make the canopy slide to the rear

instead of opening to the side. At the conclu-sion of the meeting, Nakaiima was iold tocease all work on the Nakaiima J5N1 Tenrai

and the company was also informed that they

could expect the Nakajima G8Nl Renzan to be

ierminated as well. These changes in produc-

tion and development were done to speed the

coming production of the Kitsuka. The close ofJanuary also saw the final design draft of the

Ne 20 completed and almost immediatelywork began to build the first engine. Klgisho'sAero Engine Division provided 400 machinetools and engineers and labourers began to toilday and night to realise the Ne 20.

February 1945 opened with the Japanese

naval docks in Singapore targeted and

destroyed by B-29 bombers along with contin-

ued fighting in the Philippines. A second

inspection of the Kitsuka was called for on 10

February. Present at the inspection, among the

other engineers and Kugishd personnel, wereTechnical Commander Iwaya and the manwho was destined to fly the Kitsuka, Lieutenant

Commander Susumu Takaoka. The Kitsuka

was given final approval and production was to

commence at once, even before the Kitsuka

had been flight tested. The first five Kitsuka air-

craft, No.1 through No.5, were to serve as pro-

totypes and none would be fitted rvith armourplating or self-sealing fuel tanks. In addition the

first two aircraft would not to be equipped withthe bomb carrying apparatus. February wouldalso see the Ne l28 tesied for the first time.

Unfortunately for the Kitsuka, US bombingensured that production did not go smoothly.

Due to the ever increasing number of strikes

against the industrial centres of Japan, it was

felt that it was only a matter of time before the

Nakajima Koizumi plant would attract the

attention of US bombers. Therefore, on 17 Feb-

ruary, engineering staff for the Kitsuka was

116 JnpeNsse SEcnEr PRorpcrs: ExpEnrunIlral AIRcRRpT or rHE IJA nlo IJN 1939-1945

moved to Sano in Tochigi Prefecture. Despite

the move, a sizable portion of the Kitsuka com-

ponent construction remained at Koizumi

n,hile the wings, tail assembly and the centre

and aft portion of the fuselage were con-

structed by Kugisho in Yokosuka' In the face of

further bombing attacks, production was dis-

persed among silkworm factories and build-

ings in Gunma Prefecture (northwest of

I oKyoj.

\'larch arrived in a blaze of smoke and fire as

the US ramped up their incendiary bomb cam-

paign against Japan's cities. T0ky6 and Nagoya

u.ere particular targets, the burning cities light-

ing the night sky. On March 26, the first Ne 20

engine was successfully test run from a cave

set into a cliff in Yokosuka. With the success of

the Ne 20, the Kitsuka engineering team began

to seriously consider replacing the Ne 12B withthe Ne20. It was clear that the Ne20 outper-

formed the Ne 12B and, based on the higher

thrust potential, it was decided that the Kitsuka

should use the Ne 20 even if it meant a longer

delay while the engine became available.

Although the current Kitsuka production did

not yet involve the engine mountings, a revi-

sion of the aircraft design plans was required to

accommodate the Ne20. By l\4arch 31, these

revisions were complete and the Kitsuka pro-

gram entered a stage of finalitY.

With the revised Kitsuka, some of the speci-

fications were adjusted as follows:

Maximum Speed: 620km/h (385mph) with a

500kg (1,102 lb) bomb at sea level

Range: 351km (218 miles), at sea level, at full

power

Take-off Runr 500m (1,640ft) with two 450kg

(992lb) RATO bottles

Landing Speed: 92km/h (57mPh)

Bomb Load: 500kg (1,102Ib) as normalwith the

ability to carry a 800kg (l,763Ib) bomb; a Type

3 rack would be used for the larger bomb

Protection: Reduce the bullet proof glass

thickness to 50mm and add 12mm of armour

to the front of the cockpit, while the fuel tanks

would incorporate an automatic fire

suppression sYstem

Engineers working on the Ne 20 found that,

although the initial test of the engine was a suc-

cess, there were many issues to solve. At first,

the blades were prone to cracking but this was

soon overcome. An electric starter was Iitted

into the compressor spinner that could spin the

engine at 2,250rpm; the engine would reach

ma,ximum RPM within 10-15 seconds of engine

start. Gasoline was used to start the engine and

once running the fuel was switched to a pine

root distillate using 20-30 per cent gasoline.

What was becoming a problem was how to

position the tail cone. Lieutenant Commander

Osamu Nagano and his team, along with Cap-

InrpsRIal JepaNPsE NnvY

tain Tokiyasu Tanegashima, laboured to refine

the Ne 20. The worsening bombing situation saw

the Ne 20 team moving to Hadano in Kanagawa

Prefecture, a three hour drive from Yokosuka.

Set up in warehouses belonging to a

tobacco factory, the Ne 20 group comprised

10 officers and 200 men. Here, two bench

testing stations were created and Ne 20 devel-

opment and testing continued. The process

revealed numerous flaws. At one stage the

pressure of the axial-flow compressor was

found to be too low. Nagano came to the con-

clusion that the camber of the stators was not

correct and so he took them out, bent them

on an anvil and then reinstalled them. These

were tested in the second Ne 20 to be built.

Yet another difficulty arose with the thrust

bearings on the compressor which was burn-

ing out very quickly. Nagano solved the prob-

lem by revising the bearings and bearing

rings. One problem that reappeared was

blade cracking. The blades were made from

manganese-chromium-vanadium steel and

not the more suitable nickel alloy. These

blades were then welded to the disk and, as

such, the blades did not have the strength to

withstand the operating stresses of the motor'

After one to two hours of operation, cracks

would appeare on the blade roots at the point

where they connected to the disk. The solu-

tion was to thicken the blades but this low-

ered the efficiency of the engine. However,

the Ne 20 was abte to run for four or five hours

before cracks appeared and while the engine

could have run longer, there was no guaran-

tee when blade failure would occur. Withthese improved results, work began to pro-

duce a small number of engines.

25 April 1945 would see the first Kitsuka fuse-

lage completed. This was then subiected to

stress and load testing which began on 20 May,

but with the stipulation that the fuselage was

not to be damaged during tests. Nakajima was

scheduled to produce 24 Kitsuka aircraft by

June 1945 and with the availability of six Ne 20

engines. On the surface, the Kitsuka proiect

looked to be moving along. The reality was a

far different story.

On 13 June, Vice Admiral Wada held a meei-

ing to discuss the Kitsuka. Wada addressed a

number of issues that were becoming prob-

lematic. Nakajima's G8N1 Renzen program

had to be stopped in order to free up produc-

tion capacity for the Kitsuka as both a special

attack aircraft and an interceptor' More trou-

bling was that unless the stock of aluminiumwas conserved the supplywould be exhausted

by September 1945. At best, even with conser-

vation, by the close of 1945 there would be no

more aluminium available. As a result, only

steel and wood would be left and to use such

materials would, again, have caused a revision

to the Kitsuka design. The final blow was that

high grade aviation fuels would only be avail-

able for the Honrare series of radial engines' All

other engines, including the Ne 20, would have

to make do with poorer quality fuel. This, cou-

pled with defeat after defeat for the Japanese

military, cast a very serious cloud over the Kit-

suka project and some no longer saw value in

continuing with the aircraft. Others however'

had a strong desire to see the Kitsuka taken to

completion because it would put Japan into

the jet age.

On 25 June 1945, the first Kitsuka was com-

pleted but without its engines. Although exter-

nally the Kitsuka bore a resemblance to the

Me262,that was as far as it went. The wings of

the Kitsuka had a total of 13'sweepback, the

centreline of the wings being at 9"' Wing tipslots eliminated the tip stall discovered during

wind tunnel testing and split flaps and droop

ailerons were fitted to compensate for the

heavy wing loading. Nakaiima K series airfoils

were used - a K 125 airfoil at the wing root and

a K 309 airfoil at the wing tip' The wings were

Interceptor initial concepts - data

The specifications in parenthesis rcfer t0 the modified uing uariant

Interceptor

0ne

Powerplant TrvoKrigishoNe20axialflo$turboiets,

each developing 490kg (1,080Ib) oithrust

T]?e

Crew

Dimensions

Span

Lenglh

Height

Wing area

32.8fi

30.3ft

lOfr

l42fr,

l56,2ft'

10.00m

9,23m

3.01m

13.19m'

(modified) l4.5lm'

Weights

Empty

Loaded

Useful load

Fue) capacit.-v

n'ith drop tanks

3,920k9 8,612.1 lb

(modified) 2,980kg 6.569 7lb

4,l52ks 9,153.51b

(modified) 945k9 2.083.31b

725 litres 191,5 gallons

1,450 litres 383 gals

Performance (estimated)

\'loispeed 698knXh 434mPh

al 6,000m at 19,6851t

684knYh 425mPh

(modified) at 6.000m at 19,6851t

Range 608km 378 miles

at 6,000m at 19,685f1

594km 369 miles

(modilied) al 6,000m at 19,685ft

Senice ceiling l2,l00m 39,698ft

(modified) 12,300m 40.3ilft

Armament

One Tlpe 5 30mm cannon uith 50 rounds ol ammunition

117

z

=-oE

d

E

F

E

1 18 JapaNrse Secner PRo:Ecrs: ExpoRnrrrurar- Arncnapr op rne IJA aruo IJN 1 939-1 945

of double spar construction with nine mainsupport ribs, all covered with steel and duralu-min skinning. Mitsubishi A6M Reisen flaphinges were used on the trailing edge flaps andthe wing tips were fabricated from wood andsteel sheeting. The outer wing folded upwards.The Kitsuka had a slight gull wing form thanksto 5" dihedral ofthe centre span and 2" dihedralof the outerwing. All control surfaces were fab-

ric covered. The fuselage had a slight triangu-lar shape, being composed of three sections(nose, centre section and aft). The centre sec-

tion had the centre wing span built into it andmuch of this and the other two sections wereconstructed from sheet steel due to the

unavailability of duralumin in quantity. Twenty-four bulkheads were contained within the

complete fuselage with two bulkheads comingtogether where each section met, which werethen bolted together to complete the fuselage.Trvo fuel tanks were fitted, one in front of andthe other behind the cockpit. The tail of the Kit-suka was fairly conventional and the aft fuse-lage line was kept high so that the stabilisern.ould not be effected by the jet efflux. For thetricycle landing gear, the main gear (to includethe brake system) from a Mitsubishi A6M

Reisen was modified to suit the Kitsuka and the600mm x l72mm-sized wheels retracted intothe rving. The 400mm x l40mm-sized nosen'heel was taken from the tail wheel of a

KugishO P I Y Ginga and it retracted into the rearof the nose.

After being assembled the Kitsuka was thenbroken down, loaded into trucks, and movedto Nakaiima's Koizumi plant where two Ne 20

engines awaited it. By 27 June, the Kitsuka hadbeen put back together and the enginesinstalled, and two days later weight and bal-ance checks had been completed. The Kitsukau'as then declared ready for flight testing. On

30 June 30 I 945, both Ne 20 engines on the Kit-suka were started and run for a short time.Flight testing could not be conducted at the air-field at Koizumi because the runway was tooshort and had many approach restrictions. Mis-

an'a Air Base (Misawa HikdjO), in Aomori Pre-fecture 684km (425 miles) north of TdkyO, wasalso considered since it had open approachesand was rarelyvisited byAllied long range fight-ers. However, because of the great distance itn as ruled out. Finally, it was settled that the air-field at Kisarazu Air Base (Kisarazu Hikoio)ivould be the location for the first flightbecause it was far closer to Yokosuka than Mis-

arva. Once more the Kitsuka was disassem-bled, loaded into trucks, and moved to theKisarazu airfield, adjacent to Tokyo Bay.

On arrival, the Kitsukawas reassembled andmade ready for its first flight. Unfortunately, onl4 July, during engine testing, a loose nut wasingested which completely shattered the

IupenrlL .JapanEsE Navv

blades in one of the compressors. The damageto the engine was so extensive that repairswere simply not possible and replacement the

only option. This delayed the flight for manydays. As the Kitsuka was being repaired, thepersonnel for Ihe724 Kokr-rtai, which had beendesignated a special attack unit and whichwould fly the Kitsuka in selice, had beenassembled at Yokosuka after its formation on I

July 1945. On 15 July, the new unit moved toMisawa Air Base where it began training using

Aichi D3A1 and D3A2 carrier bombers (knownas Va1 to the Atlies), which had been relegatedto the training role.

On 27 July, Lieutenant Wada conductedsome successful tari tests with the Kitsuka.High speed tari tests, however, were preparedby appointed Kitsuka test pilot LieutenantCommander Susumu Takaoka. Two days afterthe initial taxi tests, Takaoka ran the Kitsuka up

to 129km/h (80mph) and then applied the

brakes to test their effectiveness. He found thattheir stopping power was not adequate,though he felt the problem was not so severe

that flight testing had to be stopped. Groundtesting was finally completed on 6 August, the

same date that Hiroshima was devastated by

the'Little Boy'atomic bomb dropped from the

B-29 'Enola Gay'. News of this strike soonreached the Kitsuka crews, technicians andengineers.

7 August 1945 would see excellent flyingconditions and the Kitsuka was made ready forflight. Weather reports stated a 24krnlh(15mph) southwest wind and a crosswindblowing from the right across the 1,692m(5,550f1) length of Runway 20 that pointed

towards Tdkyd Bay. The Kitsuka was only given

a partial fuel load to keep the weight to 3,l50kg(6,945Ib); this allowed for approximately 16

minutes of flight time. No RATO bottles werefitted so that the take-off characteristics of the

aircraft could be assessed. Takaoka climbedinto the cockpit and made ready to take-off. On

his signal the Ne 20 turbojets were started andhe was soon ta-riing out to the start of the run-way. Once there, he extended the flaps to 20"

and kept the brakes set. So as not to cause acompressor stall, Takaoka slowly eased the

engine throttles forward and when both hadreached 11,000rpm, he released the brakesand the Kitsuka began to roll. Twenty-five sec-

onds later and after a run of 725m (2,378f1), the

Kitsuka was airborne and went into the historybooks as the first Japanese jet to fly.

At 610m (2,000ft), Takaoka levelled off. He

was instructed to not retract the landing gearnor exceed 314km/h (195mph). As a test pilothe was used to hearing the roar of a conven-tional aircraft engine and used such noise as a

means to detect problems. However, Takaokawas not prepared for the whine of the turbojets

Kitsuka Special Attacker - data

Spetifintions in parctilhesis refer to the rail launched rcrsion.

Sperial Attacker

0ne

Powerplant Tno K[gisho Ne 20 arialflou'turbojets,

each developing {90kg [1,080Ib) ol thrusl

Tlpe

Crew

Dimensions

Span

Length

Heighl

\\ring area

\Ving loading

10.00m 32.811

9.23m 30,31t

3.0{m l0ft

l3.l9m 112ft'

(Rail) 270.00k9hr' 5;.3lbril

Weights

Emptl

Loaded

5.0i0.61b

7.826..1 lb

8,99.1.8 tb

2,300kg

3,550k9

(Rail) 1.080kg

Performanre (estirnated)

l\{ax speed

(Rail)

Landing speed (Rail)

Range

(Rail)

Clinb (Rail)

Ceiling

120mph

at 19,685ft

5i2mph

l06mph

362 miles

at 19,685ft

506 rnilcs. mar

at 10.000m atil2.808ft

6i6knrih

at 6,000m

888kn,h

lTlkmih

583km

at 6,000m

8llkm

I I min 50 sec to 6.000m (19,685it)

10.700m

l2.l00m

35, r 0Jfl

39,698ft

tumament Onc 250kg [55 I lb) bomb, one 500k9 (t.I 03 lb)

Oor5. or 1tu6 Type 99 2Omm cannons

Trainer Kitsuka - data

Trainer

Two (Student and lnslructor)

Pon'erplant Two Kugisho Ne 20 arial-flow lurbojeh,

each dereloping 490k9 (1,080Ib) oithru$

T)pe

Crew

Dimensions

Span

Length

Height

Winq area

10.00m

9.23m

3,04m

l3,l9m

32.8ft

30.3ft

1{)ft

l12ft,

Weights

Loaded 4,009k9 8,838,31b

Performance (estimated)

Mar speed

Landing speed

Range

Ceiling

Sen'ice ceiling

72lkn,h

at 6,000m

l66kmih

66km at

6.000m

12.000m

10.700m

148mph

at 19,685f1

l03mph

4ll miles

at 19,685f1

39,37011

35,101ft

Armament

Likeh't0 carry lhe pa_-vload as per the Kitsuka

t19

Type

Crew

Reconnaissance Kitsuka - data that told him almost nothing outside of whathis insiruments reported. He circled Kisarazu

airfield, keeping it in sight in case of a failure

and because the airspeed kept rising, Takaoka

had to constantly throttle back to keep fromexceeding the gear down speed limit. A brieftest of the control sensitivity showed that therudder was stiff, the ailerons were heary butwere working and the elevators were overlyresponsive. When his flight time was up,Takaoka was wary of how he would land. He

did not want to drop the turbojets to below6,000rpm since that risked a flameout fromwhich he would likely not recover in time.Therefore, he chose a long, shallow drop, low-ered his flaps 40'and brought the turbojetsdown to 7,000rpm. On touchdown, he onlyneeded moderate braking to bring the Kitsukato a stop using only a little under 610m (2,000ft)

of runway. Takaoka brought the Kitsuka backto the ramp amid throngs of cheering men. The

total flight time was 1l minutes. In his immedi-ate report on the flight, Takaoka stated he hadexperienced no problems with the enginesand had no recommendations for improvingthe aircraft. During his debriefing, technicianshad removed the cowlings to the Ne 20 turbo-jets and examined each engine. They found no

faults and so gave the Kitsuka clearance foranother flight, scheduled for 1 0 August 1 945.

For the second flight, more fuel was to bestored and RATO bottles used; this wouldallow for a longer flight and test the RATO unitsas boosters. Takaoka would again pilot the Kit-

suka. Prior to the flight Takaoka examined theMTO bottles which were fitted to the under-side of the fuselage and found fault with theangle at which they were set. However, toadjust them would have taken too much timeand so instead of 800kg (1,763 lb) of thrust, the

bottles were reduced to 400kg (881 lb) each.

On the day of the second flight, Allied airpower was highly active and any flighi attemptwas bound to be spotted putting the Kitsuka atrisk. Consequently, it was decided to waii untilthe following day on 10 August. However, itwould be remembered for the drafting of theImperial Rescript on the Termination of the

War by the Japanese cabinet at the behest ofEmperor Hirohito, though the populace had noknowledge of this.

1 1 August 1945 shared a similar weather pat-

tern to the day the Kitsuka had first flown. Thedifference was that several IJN and IJA officials

of high rank had arrived to witness the secondflight. Once more Takaoka climbed into thecockpit, signalled for engine start and taxiedout to the runway. As before he extended the

flaps 20", and after receiving the signal to take-

off, he slowly opened the throttles until the

engines had reached 1 l,000rpm before releas-

ing the brakes and the Kitsuka rolled fotwards.

At four seconds into the take-off roll, Takaokaactivated the RATO units. Immediately, theacceleration caused the nose of the Kitsuka topop up, the tail slamming onto the runway.Takaoka fought to get the nose down by jam-

ming the stick forwards but he received noresponse from the aircraft's elevators. The twoMTO units burned for a total of nine secondsand during eight of those seconds Takaokawas helpless and unable to correct the nose upcondition. One second prior to the units burn-ing out, the elevators finally took effect and thenose came down so hard Takaoka was surethe front tyre had blown when it contacted therunway. Takaoka felt a sense of decelerationas the Kitsuka reached the halfway point onthe runway - his speed at that point was1 66km/h/1 03mph. A second later, with the feel-ing of deceleration still present, Takaokadecided to abort the take-off and he cut thepower to the engines. Unfortunately, the brakeissue Takaoka had discovered during high-speed taxi tests now came back to haunt him.

Despite maximum application of the brakes,the Kitsuka showed no signs of slowing andTakaoka was rapidly running out of runway. As

he neared one of the taxiways, Takaoka heldthe left brake in an attempi to make the Kitsukabring its left wing down into the ground to

bleed off speed (known as a ground loop). The

Kitsuka's nose turned slightly but this then putthe aircraft on a crash course with a group ofhangars and buildings. Takaoka reversed thebraking, holding the right brake. The Kitsukacame back around onto the runway anddespite Takaoka working the brakes, it was tono avail. The aircraft ran out of tarmac andcrossed the 100m (328ft) of grass overrunbefore the landing gear caught in a drainageditch and collapsed. The Kitsuka slid along its

belly until finally coming to a halt by the edge

of the water of Tokyd Bay. The damage to theKitsuka was extensive. In addition to the man-gled landing gear, the two Ne 20 engines werebadly damaged, having been iarred from theirmounts but still remaining attached to thewings. Initial assessments suggested that the

damage was so severe the Kitsuka could not

be repaired. On the positive side, the aircraft

did not catch fire and causes of the accidentwere swiftly looked into. IJN Captain It6, whowas present for the flight, was thankful that theKitsuka did not become airborne with the nose

high attitude during the RATO burn. Had thathappened and once the RATO bottles cut out,the Kitsuka would have most likely crashedinto the ground. A motion picture camera cap-tured the flight and the film developed to see ifit could shed any light on the crash.

On 15 August, the film of the ill-fated flightwas studied but proved inconclusive as towhether or not the Kitsuka was airborne once

Reconnaissance

Tlvo (Pilot and 0bseruer)

Powerplant Trvo K0gish0 Ne20 arial-florv turbojets,

each developine 490kg (1,080Ib) ofthrust

Dimensions

Span

Length

Height

Wing area

10,00m

9,23m

3,04m

13.19m'

32.8ft

30.3ft

1oft

l42ft,

Weights

Loaded 4,24lkg 9,349,81b

Performance (estimated)

Max speed

Landing speed

Range

Ceiling

Service ceilnq

Zlktr/h 448mph

at 6,000m at 19,685ft

169kn/h lO5mph

666km 414 miles

at6,000m at 19,68511

12,000m 39,370ft

10.700m 35,104ft

fumament

None (posibl.v trvo Type 5 30mm cannons)

Interceptor definitive version - data

Type

Crew

lnterceptor

0ne

Powerplant Trvo lshikawajima Ne 130 or two Nlitsubishi Ne 330

arial-liow turbojets, each developing 900 or J,300kg (1,984Ib or 2,866Ib)

of thrust respeclively

Dimensions

Span

Length

Height

Wing area

\[ring loading

10.00m 32.8ft

9,23m 30.3ft

3.04m 10ft

l3.l9m' 142ft'

302,71k9h' 62lb/ft'

Weights

Empty

Loaded

Useiul load

6,746.1 tb

9,329.9tb

2,072.3tb

3,060k9

4,232k9

940k9

Perf ormance (estimated)

NIar speed

(Ne 130)

Landing speed

Range

443mph

ar 19,685ft

96mph

369 miles

492 miles at cruise

713km/h

ar 6,000m

I 54kr[/h

594km

792km

speed

Climb

Ceiling

I I min 18 sec ro 6,000m (19,685fr)

12,300m 40,354ft

Armament

Trvo Tlpe 5 30mm cannons or two Ho-155 30mm cannons (lJA); one

500kq (1,102 lb) or 800kg (1.763 lb) bomb (if used as a fighter-bomber)

120 JapaNEsE SEcnEr Pno:Ecrs: ExpeRtuENral ArRcnnnr oF THE IJA AND IJN 1939-1945

the RATO bottles were exhauasted, as wassuspected. This would have explained theheary impact of the front landing gear on therunway and the sense of deceleration experi-enced by Takaoka. In any case, the Kitsukarvould never fly again for at l2.00pm the Impe-rial Rescript on the Termination of the War wasbroadcast on the radio bringing World War 2 toa conclusion.

The end of the war would see none of theKitsuka production plans realised. Naka.jima,

bv the close of December 1945, was to haveproduced 200 Kitsukas. In reality, Nakajimacompleted only one with a further 22 underconstruction. The KyushuHikoki K.K. was, also

br,the end of the year, to have turned out 135

Kitsuka aircraft but was only able to begin con-struction of two aircraft, started in July 1945,

rvhich remained unfinished by the close ofhostilities. A third producer, the Sasebo Naval

.\senal (Sasebo Kaigun Kdshd), was sched-uled to have begun production of the Kitsuka inSeptember 1945 with 115 completed by theclose of December. The fourth production lineu'as to be at the Kasumigaura NavalAirArsenalu'ith the commencement of Kitsuka construc-tion scheduled for October 1945; 80 aircraftu ere to have been completed by the end ofDecember.

A number of variants of the Kitsuka wereplanned, none of which would see completioncome the capitulation. One of these was a two-seat trainer. Given the nature of the Kitsuka, itn.as appreciated that a trainer would be

required to help the conversion of pilots usedto conventional piston engined aircraft to thepeculiarities of a turbojet powered aircraft.Five of the Kitsuka airframes under productionbi' Nakajima were modified by including a sec-

ond cockpit for the instructor. Outside of theinclusion of the additional cockpit, it is

unknown exactly whai other changes weremade in the Kitsuka to accommodate it. Ifthere were a parallel to the German\le 2628-1a two-seat trainer, the rear fuel tankn-ould have been removed to make room forthe instructor's cockpit. The German solutionto the loss of fuel was to utilise the two frontbomb racks for drop tanks. Whether Nakajimaconsidered the use of drop tanks (as the Kit-suka could use them) or simply accepted thereduced endurance for the sake of expediencyis not known. The two-seat trainer would be

the only variant of the Kitsuka to reach the pro-

duction phase.

It was planned that some of the two-seaterswere to be modified for reconnaissance roles.

The instructor's cockpit was to be removedand replaced with a crew position for anobseler. He was to have a Type 96 Modet 3

radio set at his disposal for use in relaying tar-get information to other aircraft. It is unknon'n

InpeRral JapanssE Nnvv

oEozJ2

trl!if"'a

:.1

i::ti:rt1

t21

Nakajima Kitsuka - data

Contemporari€s Messerschrnitt I'le 252A-1:ftJ3 and I'le 262A-5a

(Germanl), \'lessenchmitt l\'1e 2tj2A-2aitl2 (Germanl). \'lesserschmitt

Me 2628-la (Germanr'), l\'lesserschmilt Mc 262C-1 a. ['1e 262C-2b,

and l\'le 262C-3 (German.-v)

Deplolment

None. One finished aircralt lras built bv Nakajima (hno if one counts the

airirame completed lor load testing) rvith a iudher 2l in various slages

ol conslnrction bv \\'als end.

nons would be used for self-defence and for fir-ing at the target before ramming the aircraftinto the victim using any remaining fuel andammunition as the secondary explosive ele-ment. A variant of this Kitsuka was to utilise a

200m (656ft) launch rail that Klgisho had beendesigning and which they expected to have

ready for testing by September 1945. Using arocket booster, the Kitsuka would leave thelaunch rail at 220kmih (137mph) at an acceler-ation of between three to four'g'.

In regards to lhe 724 K6kutai, wiih the end ofthe war they would never see their Kitsuka air-

craft. Ii was planned that by November 1945 theunit would have been based near Yokosuka at

a site along the Miura Peninsula, west of TokyoBay. It was expected that by then the unit wouldhave received sixteen Kitsukas. In addition, the

unit was to use one of the handfuls of Kawan-ishi E15K1 Shiun (meaning'Violet Cloud'; code-named lVorm by the Allies) reconnaissancefloatplanes, which were removed from activeservice follorn'ing their disastrous combat debutin 1944. The Shiun, operating from a nearbyhar-bour, would locate the shipping targets, markthem and then loiter in the area to broadcastradio signals. The Kitsukas would then be

rapidly launched and, by means of the radio sig-

nals received through the Kuruku system,

attack the ships at low level with bombs andramming tactics. Had the reconnaissance ver-

sion of the Kitsuka gone into production, the724 Kdkltai was to receive it as a replacementfor the far more vulnerable Shiun.

Finally, with the close of the war, none of theprojected turbojet successors to the Ne 20

would enter production. One prototlpe of theIshikawajima Ne 130 had been completed byJune 1945 but testing was unfinished by thetime the war ended. Nakajima started devel-opment of the Ne230 in May 1945 and hadthree under construction byAugust 1945. How-ever, none of the engines were completed ortested. Mitsubishi was unable to construct a

Ne 330 and so it remained on the design board.A note about the use of the name Kitsuka as

opposed to the more commonly used Kikka.Kitsuka is the proper translation of the kanjicharacters. However, it is pronounced'kikka'.Kikka was used in post-war reports as phonet-

ically it approximated to Kitsuka and thus has

become the accepted name of the aircraft.Neither name is incorrect. Also, some sourcesuse the J9Y1 (or sometimes J9N1) designationfor the Kitsuka. While logical for the intercep-tor version of the Kitsuka, there is no evidencein wartime Japanese sources to support thedesignation. One may also find the designationJ8N1 used but this is not supported.

T}?e

Crerv

Powerplant TuoK[gish0Ne20arial-flosturbojets,

each deleloping.l90kq (1,080Ib) olthrun

Sunivors

Nakajima Kitsuka (tail numbcr A.l 03)

With the loss 0f lhe onh,completed Kitsuka follo[ing its crash on I I

August 1915, examples captured bl the tls lolloning the uativete from

lhe stocks of incomplete Kitsuka aircrafl found in Nakajima and

KvushI s plants. Th;s particular Kitsuka anived at ]iAS Patuxent Rii'er

and on l8 0ctober 1946 was shipped to San Dicgo. California. The

aircraft erentuall.-v lound rts uat back to the Paul. E. Carber facilitl

nhere it is believed to be the second Kitsuka held in storage there,

Some sources hai'e the serial for this Kitsuka as 7337.

Nakaiima Kitsuka (tail number A-l 04)

Also at NAS Patuxent River u'ilh A-103, it u'as lalel shipped to NAS

\\iillou, Grove in \Villolv Crove, Pennsit'ania on 23 October 1946.

Folloning its arriral, no iurther trace of the Kitsuka is knonn.

\akaiima Kitsuka (no tail numbcr assi{ned)

This Kitsuka was received in the I S and appearcd on a storage manifesl

in 1950 bcing housed al NAS Norlolk in Noriolk, Virginia. 1n 1 960. it u,as

shipped to the Paul E. Garber facilit\'. Fron 1972 until the lacility closed

to the public. it rvas on displav hanlinl from the ceiling Gee page I 18).

Attack Bomber

0ne

Dimensions

Span

Length

Heighl

\Ving area

\\iing loading

Power Ioading

10.00m 32.8ft

5,21m I 7.2ft (rvings folded)

9.23m 30.3ft

3.04m l0ft

l3.l9m ll2ft-

268.i3kgim' S5lbrlt'

J.6kgrkg 3.7 lbllbst

Weights

Emptl

Loaded

Mar loaded

llseful load

2,300k9

3,5i0kg

4,3l2kg

1.249k9

5,0i0.61b

7,826.4Ib

9.506.3Ib

2,i53.5 lb

Performance

['1ar speed

Mar speed

'Iake-off speed

Landinq speed

Take.olflength

Climb

Ceiling

Senice ceiling

Fuel capacit.-v

Range

62lkmih 386mph at sea level

6i9kmih 122mph

at 6,000m at 19,6851t

695knrh 432mph

at 10.000m at i'l2,80llit

r09kmih 3l6rnph

at sea level, nith 500kg (l,l02lb) bomb

i48kn'h 92mph

at autight of3.95Okg (8,708.2Ib)

lsskmih 98mph

at a rveight ol2,57()kg (5.665.8Ib)

501m 1.653.5ft

u,ith RATO u'ith zero nind at

a n'eight ol 1,200m (9,259,1 lb)

1,363m 1,{71,ift

lrithout RATO rvith zero rvind at

a ueight oi 3,950kg (8,i08.2 lb)

583km 362 miles

at 6,000m at 19,685tt

888km 552 miles

at 10,000m atlJ2,808it

203km 126milcs

\\'ith ma\imum bomb load

555km 345miles

nith 551 1b bomb load

918km 589 miles at cruise speed

l2 min l6 sec to 6,000m (19,685ft)

32 min 12 sec to 10,000m (32,808ir)

12,000m 39,370ft

10,700m 35,l0llt

i25 litres 191.5 gallons

1,1i0 litres 383 gals u,ith drop lanks

if any cameras were to be fitted but itwould notbe unreasonable to conclude ihat the obselverwould at least have had a hand-held camera.

An interceptor version of the Kitsuka wasdiscussed, as previously mentioned, and anumber of general arrangements for it wereconsidered. One of these was the inclusion ofa single Type 5 30mm cannon with 50 roundsof ammunition installed in the nose. A seconddesign was to feature enlarged and extendedwings incorporating flaps and double-edgedleading slots. A more definitive interceptor wasto replace the Ne 20 engines with either Ne 130

or Ne 330 turbojets. A second cannon was to beadded in the nose. Interestingly, it appears thatif the IJA had used the Kitsuka, the Tlpe 5 can-nons would be replaced with two Ho-155

30mm cannons. This may have been a stopgapor fallback if the IJA's own Ki-201 Karyu failedto materialise. With the heavier weight thestructure of the Kitsuka, including the landinggear, would have been strengthened. A fighter-bomber model was envisioned for the defini-tive interceptor by including a fitting for a single

500ke (1 ,102 lb) or 800kg (1 ,763 lb) bomb.As originally planned, a model of the Kitsuka

lvas proposed for shimpu missions. Similar tothe Kitsuka as constructed, this version was tocarry either a 500k9 (1,102 lb) bomb, a 250kg(551 lb) bomb or two Type 99 20mm cannons.With the latter, it could be assumed the can-

Armament

0ne 500k9 (1,102 lb) or 800 (i,i63 lb) bomb

122 JapeNssr SEcRor PRoLecls: ExpsRrMeNrnL ArncRnpr oF rHE IJA AND IJN 1939-1945

I tr.-/

The Rammer

The practice of tai-atari, which literally means'body crashing', was not unique to Japan. Thedeliberate ramming of one aircraft by anotheraircraft has happened as far back as WorldWar 1 when Imperial Russian Air Force pilotPyotr Nesterov used his 1912 Morane-Saulnier monoplane to ram an Austrian Alba-tross B.ll on 26 August 1914. In World War 2,

the first ramming attack went to Lt. Col.

Leopold Pamula who used his stricken PZL

P.lic to down a Messerschmitt Bf 109 on 1

September 1939. It would be the Russians,

Germans and Japanese who would makeramming a part of their war doctrine.

O lupR ArncRapr

Other Aircraft

\\\

Whereas the Japanese would simply use

available aircraft to conduct ramming ortai-atari attacks, the Germans took it a siepfurther by producing and designing aircraftspecific to the task. One operational examplewas the Focke-Wulf Fn' l90A-8/R7. To enablethe fighter to penetrate bomber formationsthe Rammjiiger (or Sturmbocke) was fittedwith armour plating to enable it to weatherdefensive fire as well as possibly survivinga successful ram. Sturmstaffel 1 was thefirst Luftwaffe unit to operate the fighter.As the war went on and US bombers filledthe skies, and the Luftwaffe was moreand more hard pressed to stem the tide, anumber of dedicated rammer aircraft designs

The aircraft depicted here sports the colours andmarkings of the 53rd Sentai operating in defenceof the Japanese homeland.

appeared. One of them was the ZeppelinRammer.

The Rammer was a small, single seat air-craft that was towed into the air. As it wasdesigned for ramming, the constant cordmain wings were strengthened by the use ofthree tubular spars along the forward edge ofthe wings. The remainder of the aircraft wasbolstered to allow it to withstand impactforces. A single Schmidding 109-533 solid fuelrocket developing 1,000kg (2,205Ib) of thrustwas fitted into the tail and the motorprovided

z

123

a total of twelve seconds of thrust. In the nose

were fourteen R4M rockets or a single SG 1 18

battery. The cockpit was within an armouredtub providing 28mm of armour plate in the

front and sides with 20mm in the rear.

The glazing was 80mm of bulletproof glass inthe front and 40mm thick on the sides. The

method of attack was to tow the Rammerwithin .48km (0.3 of a mile) from the target

and release it. The pilot would ignite the

rocket motor to boost speed and fire off the

nose weapon at the first target before makinga ram attack on a second (or the same) tar-get. After engaging in the ram attack, the pilotwould glide back down to earth. The Ram-

mer was test flown, without power, in Janu-

ary 1945 and a pre-production batch ofsixteen aircraft was ordered. However, Zep-pelin's production facilities were destroyed

by US bombing before their constructioncould commence.

The Japanese would use aircraft already inoperational seruice for ramming attacks suchas that Kawasaki Ki-45 and even strippeddown Kawasaki Ki-61 Hein fighters. It waslong thought that Japan never developed a

dedicated rammer aircraft of its own but this

is no longer the case. Recently discovered inthe archives of the Japanese National Insti-

tute for Defence Studies is just such a project.The aircraft was a joint venture between

the IJA and the IJN, something that occurredwith more regularity towards the close of the

war. The design was based on the Syusui-

shiki Kayaku Rocketto (meaning 'AutumnWater'-type ram attack rocket), a projectstarted in March 1945 for a unmanned,remote controlled anti-bomber missile. Theplan was to ground launch the missile, guide

it remotely towards the target, engage the tar-get via ramming, and then recover the missile(if it suruived the collision) for reuse. Design

work was carried out by the Kokukyoko (the

Aeronautical Bureau) and, although a mock-up was completed, the war ended beforefinalised production plans could be com-pleted, let alone the missile ever being tested.

The missile's design borrowed heavily fromthe Mitsubishi J8M Sylsui in terms of itsshape. Interestingly, the Messerschmitt Enz-

ian anti-aircraft missile had a shape influ-enced by the company's Mel63 rocketinterceptor, of which the J8M was the Japan-

ese version (see page 96).

The piloted version used much the same

design as the missile and was a small, tailless

aircraft featuring low mounted 45' sweptwings. The fuselage was bullet shaped with alarge vertical stabiliser into which the cockpitwas blended. Located in the back of the fuse-

lage were four Type 4 Mark 1 Model 20 rock-ets, the same as those used on the Kugisho

MXYT Oka which on such a small aircraftpushed the maximum speed to an estimated1 .1 25km/h (699mph or just over Mach 0.9 1) -i.e. a transonic speed. With a speed in the

transonic range, this aircraft would have pre-

sented a formidable challenge to the Japan-

ese given that even the Germans had only iuststarted investigating the problems of high-speed flight when their jet and rocket aircraftbegan to push into such speeds with the

resultant issues of compressibility. lt is

unknown if the Japanese rammer had sweptwings because the designers understood theprinciples in relation to overcoming com-pressibility problems at transonic speeds, or ifthe shape was chosen as a means to provide

an angled cutting surface to facilitate ram-ming attacks, or as a drag reducing planform.The wings were strengthened to withstandthe high impact forces experienced whenstriking the enemy bomber. Even though the

rammer could rely on speed as a defence

when under power, it still had to contendwith the defensive armament of the B-29 andthought the pilot had some measure ofarmour plating and bulletproof glass to pro-tect him. The aircraft was certainly capable ofgliding back to base to be refuelled and

relaunched once it had conducted its attacks.

Given the small size of the plane, no landinggear was fitted. As such, it is likely the under-side of the fuselage was reinforced or had askid installed. How it was to be launched is

unknown - it could have been towed aloft,

catapult launched or perhaps even verticallylaunched.

In a ram attack, typically the tail would be

targeted because the loss of the tail assembly

would send the bomber out of control. Strik-

ing the wings and engines was another focus

of ramming attacks. Finally, the aircraft fuse-

lage was the other key area to strike. Theprobable mission profile of the rammer flying

from a ground base would include beingpositioned within very close proximity oflikely bombing targets. With the short burntime of the rockets (8-10 seconds) the air-

craft's operational radius would have beenvery limited. After launching, as bomberscame into range the pilot would attempt to

ram into either the tail or wing of the target

with the ob.iective of severing it from the fuse-

lage. If enough speed momentum remainedafter the initial hit, another ram attack wouldbe made. Should the aircraft remain in flyable

condition and if the pilot did not elect to ramhis entire plane into a target, he would returnto base where the rockets would be replaced.If the bombers were still close by, he could flyanother sortie. If the rammer was towed intothe air, the rockets would most likely have

been fired on approach and again after hitting

a target. This would provide enough power togrant a second pass with sufficient speed toallow for significant damage to be inflicted on

the bomber when it struck.However, the Japanese rammer would

remain a paperproject only. It is unclear if the

design was to be the definitive rammermodel or simplv a proposed concept.

The Rammer - data

As lhe design uls neaer buill, the specifications arc estimales based on

the oiginol design sketch and dalI.

Tlpe Rammer

Crew One

Powerplant Four Trpe 4 N'lark I l\'lodel 20 rockets rvith a

combined l, l02kg (2,232 lb) of thrust

Dimensions

Span

Length

Height

\Ving area

Wine loading

Polver loading

4.41m

2.89m

N/A

N/A

Ni/A

l4.5ft

9.5ft

Weights

Emptv

Loaded

\'larimum

N/A

N/A

N1A

Performance

Speed

Climb

Range

Endurance

Ceiling

l,l25km/h 699mph

32 seconds to 10,000m (32,808ft)

N1A

N/A

Armamenl

\one

Deployment

None. The rammer remained a design dralt only

124 JapanEss SEcnsr PRo:scrs: ExpnRrupnraL AIncRapr oF THE IJA,qto IJN 1939-1945

Kamikaze, which in Japanese means 'divinewind', was not a term used by the Japaneseto reference their special attack units butcame into common use in the West. Instead,

shimpl and shimbu were more often used byboth the IJN and the IJA respectively. May1944 would signal the beginning of dedicatedsuicide attack missions against the US andher allies. The effect of being on the receivingend of such attacks was horrific and wouldtake its toll on US sailors.

A poslwar report by the US StrategicBombing Survey bluntly stated that kamikazeattacks were effective and given the situationfor the Japanese, very practical. Statistics ofsunk and damaged US ships during thePhilippines campaign (October 1944 to Janu-ary 1945) showed that kamikaze attacks werefarmore effectual. Of course, being subjectedto such attacks wreaked havoc on morale as

rvell as a surge in mental illness. The US Naly,the focus of the majority of kamikaze attacks,saw such illness rise by 50 per cent in 1944

rvhen compared to 1941. So bad was theproblem that during the Okinawa campaign,the US Naly stopped warning crews thatkamikaze attacks were to be expected as

they only added to the sailor's stress levels.General George C. Marshall wrote in a 1945

report to the US Secretary of War that, 'TheAmerican soldier has a very active imagina-tion... and is inclined to endow the death-dealing weapons of the enemy withextraordinary qualities...' And thus the'Kamikaze Airplane'appears on the scene.

Following the close of World War 2, an illus-tration of an aircraft appeared in either Popu-Iar Mechanics or Popular Science magazine.The aircraft, labelled a kamikaze plane, was acurious mixture of what appeared to be thetail of a Mitsubishi A6M Reisen, a fuselage nottoo unlike the Nakajima Kitsuka and a canopysimilar to aircraft such as the Kawanishi N1KlKyofu (meaning 'Mighty Wind' but known as

Rex to the Allies) or the Nakajima Ki-84 Hay-

ate (meaning 'Gale'; Franh to the Allies). Even

more curious was the fact that the aircraftused air-cooled radial engines, one in eachrving, but in a pusher configuration.

The Kamikaze Airplane was said to havebeen sighted by some US Naly crew mem-bers as it flew over their ships. It was from

The Kamikaze Airplane - data

.\io specilications uere proDided fot the atct1ft.

DeploXment

\one. The Kamikaze Aircrafl $'as strictlv fictional,

The Kamikaze Airplane

their descriptions that the illustration of theaircraft was created. The result was certainlyunlike any plane then in the theatre but there

is some precedent in terms of genuine air-

craft being misidentified. One example wasthe'Kawasaki Type 97 Medium Bomber' thatwas given the codename Julia. Because ofvery inaccurate illustrations of the plane thatwere derived from awritten description,Jultawas in fact the Kawasaki Ki-48 (frly). It mayvery well be that the Kamikaze Airplane wasactually a US Grumman F7F-2N Tigercat ofwhich two US Marine Corps squadronsequipped with the plane began operatingfrom Okinawa in September 1945. One was

VMF(N) 531 while the second was a photoreconnaissance unit. With the Tigercat beingnew to the Pacific Theatre, it can be surmisedthat some sailors and crew mistook the twin-engine fighter for a Japanese plane and sub-

sequently described something other thanwhat was actually seen. However, the

Kamikaze Airplane was written off as a spec-

tre of the imaginations of sailors who had

borne the brunt of kamikaze attacks.

The Kamikaze Airplane illustrated is derived fromthe magazine artwork and is shown in the coloursof the l8th Sentai, operating from Kashiwa Airfield'Japan, spring 1945.

OrHER Arncnnpr 125

zf

UJ

The illustration provided here is an interpretationof the Tlpe 0 as described in the O.N.I. 249 manualand is shown in the colours and markings of the3rd Chutai, 26th Sentai.

Mitsubishi T.K.4 Type 0 - data

No informalion on the specifications, if ony et:er existed, is auailable for

the T.K.4or the TWe 0.

Deployment

None. The T.K.4 existed only as an illustration in a magazine while the

Type 0 was a descdption in a manual.

Mitsubishi T.K.4 Tlpe 0

At the outset of hostilities in the Pacific, Amer-ican intelligence had very little information on

.just exactly what aircraft the Japanese werefielding. In part this lack of knowledge sprangfrom poor intelligence management and cen-sorship of periodicals and other publicationsby the Japanese authorities. In scrambling todocument Japanese aviation, invariably US

intelligence officers turned to Japanese mag-azines as a means of gaining information.However, there were pitfalls to using suchsources and the Mitsubishi T.K.4 Type 0 wasjust one example.

The T.K.4 appeared in a section of theJapanese aviation magazine Sora entitled'Dreams of Future Designers'. The issue waspublished in April 1941. The T.K.4 wasdepicted as a twin-engine fighter whosedesign was rather similar to the GermanMesserschmitt Bf 1 10. The aircraft, although afighter, was shown with a glazed nose alongwith the expected glazing over the pilot andcrew positions. Each of the low mountedwings sported an inline engine in a verystreamlined cowling, each motor driving athree-bladed propeller. What weapons theT.K.4 carried was unknown nor was the crewcompliment listed, although two or threecould be estimated. Also lacking was anydata on the performance of the T.K.4.

lnformation on the T.K.4 would also appearin a US magazine. The 25 December 1941

issue of F/rghf mentioned the aircraft as atwin-engine, twin-tail monoplane fighter.From these sources, the US intelligencedetermined that the T.K.4 was a bona fidefighter that would be encountered in combat.Maior Frank T. McCoy, Jr., the head of theMaterial Section of the Directorate of Intelli-gence, Allied Air Forces, Southwest Pacific

Area, would assign the T.K.4 the codenameFranh, Iaking his ornrn first name. It wasMcCoy who arrived at the method of assign-ing names to Japanese aircraft in order tosimplify identification.

At some point, the T.K.4 Type 0 fighter tookon a completely different appearance. Whenthe Japanese Aircraft Manual, O.N.l. 249(Office of Naval Intelligence), was first pub-lished in December 1942, the Mitsubishi Type0 was no longer called the T.K.4. Although noillustration was provided in the manual, theType 0 was described as an army fighterbased on the Dutch Fokker D.)filll. TheD.XXIII was a twin-engine fighter thatmounted the engines in the fuselage in apush-pull configuration. It was also a twin-boom design that was under developmentand in flight-testing until the German inva-sion. The manual stated that the Type 0 usedtwo German BMW engines, each developing750hp, but that a redesign of the aircraftwould see it using two 1,000hp MitsubishiKinsei air-cooled radial engines. No furtherinformation was made available.

When the original T.K.4 Frank failed tomaterialise in combat, McCoy removed hisname from the T.K.4 and reassigned it to theNakajima Ki-84 Hayate (meaning 'Gale')which was a fighter very much in use, beingfirst encountered in combat in early 1944. TheType 0, as described in the O.N.l. 249 manual,was given the codename Harry after ColonelHarry Cunningham, a friend of McCoy's, whowas the intelligence officer for General EnnisWhitehead. At the time it was believed thatthe Type 0 would eventually be seen in actionbut, just like the T.K.4, it never would and theType 0 was dropped from the intelligencepublications.

126 Jlp.tr.rEso SEcnEr Pnotects: ExpnnrMenral ArRcRnpr oF rHE IJA AND IJN 1939-1945

The T.K.4 was not the only Japanese aircraftuncovered in the pages of Sora. The same'Dreams of Future Designers' article in whichthat image was unearthed also included theNakajima AT27. Several months later, the 25

December 1941 issue of Flight, a US maga-zine, would also feature these planes, alongrvith several others, lending credence to theidea that they were genuine aircraft in use bythe Japanese.

The AT27 was novel in a number ofrvays. On the outside, the fuselage wassleek and well streamlined. The wings werelow-mounted with a conventional tailplane.Inside, however, the AT27 featured twoi 2-cylinder inline engines each rated at1,250hp and was reported to obtain a mari-mum speed of 660km/h (4i0mph). Oneengine was in the nose while the otherrvas situated behind the cockpit. Contra-rotating propellers were used, the rear enginedriving its propeller via an extension shaft.To maintain the excellent aerodynamic prop-erties, the engines were reported to havebeen provided with a'steam cooling'system.This may have been a surface evaporationsystem. Such a system took the steamcreated after the water had passed throughthe engine and ran it through piping in thervings where the cooler airflorv would con-dense the steam back into water that wascycled back through the engine. The pilot

Nakajima AT27

was afforded some protection by the enginesin front and behind him but the AT27 couldalso carry additional armour not only for thepilot but for the engines as well. What tlpe ofweapons the AT27 was to carry were notknown.

Based on its appearance in the magazines.the AT27 was believed to be a bona fidefighter that could be encountered and thusAllied intelligence gave the AT27 the code-name Gus. However, the AT27 would neverbe seen or met in battle since, as was laterdiscovered, the aircraft was flctitious. Gus

was soon dropped from the Japanese aircraftintelligence rolls.

Interestingly, the AT27 was very similar tothe very real Kawasaki Ki-64 whose develop-ment began in October 1940. Both used 12-

cylinder inline engines, one in the nose andthe other behind the cockpit, driving contra-rotating propellers. In addition, both used asurface evaporation system. Perhaps bysheer coincidence, one ofthe Japanese illus-trations of the AT27 that was published inSoro and later in Flrghl showed it sporting thenumber 64 on the fuselage.

The 3-view illustration of the AT27 is in themarkings and colouration of an aircraft of the244th Sentai operating in the defence of Tarkyq1944-1945. The side view below depicts the AT27as it appeared in Sora magazine."

NakajimaAT2T - data

Contemporaries Republic XP-72 (l.S), Fisher XP-i5 Eagle (US)

Porverplant Tnol2-c1'linder,water"cooledV-engineseach

deleloping l,2i0hp and each driving a three-bladed propelleL

Fight€r

0ne

Tlpe

Crew

Dimensions

Span

Length

Height

Wing area

Wing loading

Porver loading

\,A

\1A

22.0lmr 2371t

239.23k$m' .l9lb/ft

NlA

Weights

Emptv

Loaded

Usable load

3,629kg

5,262k9

l,633kg

8,000 tb

I l,600lb

3,600 1b

Performance

['lili speed

Cruise speed

Range

Endurance

Climb

Ceiling

660kn'h

N/A

2,0l2km

N/A

NlA

NlA

1l0mph

1,250 rniles

Deplolment \one. The AT27 was purell a fictional aircralt

lt

z

l

3

OrHeR AIRcRapr t27

-*-*'d.;ry

%x1

\hF

6', _@

:in

itI

{li-

${

rili,lii1ti:trllil

t:t1

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128 JapaNgse SEcRrr PRo.lscrs: ExpeRruENlal Arncnarr op rHE IJA aruo IJN 1939-1945

S-31 Kurowashi

As we have already seen, the April 1 941 issueof Sora misled Allied intelligence over thenature and extent ofJapanese aircraft design.As the war continued, none of the four aircraftthat feature in the April issue were encoun-tered and subsequently dropped from Alliedintelligence publications. However, Soro con-tinued and so did the section responsible.How often the 'Dreams of Future Designers'portion of the magazine appeared is notknown but one issue from either I 944 or 1945

contained a design that was nothing short offantastic. This was the S-31 Kurowashi, orBlack Eagle.

The Kurowashi was a four-engine hear,y

bomber concept. What was unique about theaircraft was that all of the engines werehoused within the fuselage and theKurowashi used a push-pull configuration.Both in the front and the rear of the fuselagewere two 2,500hp, 24-cylinder, liquid cooled,inline X-engines, driving a pair of contra-rotat-ing, three-bladed propellers via a gearbox.

With this powerplant the Kurowashi was toboast a top speed of 689km/h (428mph), butsuch a powerful engine of this type would notsee service with the Japanese air forces.However, this was not for a lack of trying: itmay or may not be that the originator of theKurowashi was aware of the Yokosuka YE3

series of engines.In 1940, the IJN initiated development of

the YE3A, a 24-cylinder, liquid-cooled,X-engine that was to produce 2,500hp. AnX-engine is produced by having paired V-

block engines horizontally opposed to eachother with the cylinders in four banks drivinga common crankshaft and thus, whenviewed head-on, appearing as a 'X'. Themajor benefit to using such a configuration is

that the engine is more compact than a com-parable radial engine or standard V-engine.However, X-engines are far more complexto construct and service and are heavier. Itwas not be until October 1943 that the firstYE3B [Ha-74 Model 01] (also known as theKen No.l) was completed and tested. TheYE3B was designed to be housed inside thewing. A second model, the YE3E [Ha-74Model l1) (Ken No.2), was rated at 3,200hpand was slated to be completed in March1944. Unlike the YE3B, the YE3E wasdesigned to be housed within the fuselage. As

it was neither engine would see service by thetime the war ended. Interestingly, a survivingYE3B engine was fitted with a two-stagereduction gear and a extension shaft thatwould have been used to drive two, contra-rotating propellers.

With a wingspan of just over 33m (107ft),

the Kurowashi was by no means a small air-craft. The plane was just under 21m (70ft) inlength and a height iust shy of 6m (20ft).

These dimensions were very similar to theBoeing B-17 bomber. The Kurowashi sportedhorizontal stabilisers which ended in ovoidshaped vertical stabilisers.

The Kurowashi was certainly not lackingforweaponry. A total of eight 7.7mm machineguns and four 23mm cannons were carriedby the bomber. 7.7mm was a calibre used byboth the IJA and the IJN, but on the otherhand, the Japanese did not field a 23mm can-non in any form, either in aircraft or on theground. The IJN did use a 25mm anti-aircraftcannon (Type 96) but did not apply theweapon to aircraft. The IJA also experi-mented with a 25mm aircraft cannon butabandoned it in favour of the 30mm cartridge.Why the creator of the Kurowashi decided touse 23mm as the calibre for the cannonsremains unknown.

What is known is the novel arrangement ofthe defensive armament. Fitted directly intothe leading edge of each wing were two balltrlrrets. The outer turret contained one 23mmcannon while the inner turret sported two7.7mm machine guns. Directly oppositethese front-facing turrets was another set ofball turrets. As the trailing edge of the wingwas too thin to allow the turrets to be inter-nally mounted, each turret was fitted into theend ofa nacelle that extended from the backof the wing. Therefore, each wing was fittedwith four turrets for a total of two 23mm can-nons and four 7.7mm machine guns. To con-trol these turrets the Kurowashi relied on twogunners, the bombardier and co-pilot. Bothgunners had positions facing to the rear of theaircraft behind the bomb bay. The first gunnerstation was in the upper portion of the fuse-lage while the second was in a ventral station.Weapon sights were provided along with thecontrols to manipulate and fire the turrets.The bombardier and the co-pilot stationswere also provided with a sight and turretcontrols so that if they were not occupiedwith other duties they could man theweapons. It is likely that the bombardier andco-pilot had control of the forward facing tur-rets while the two gunners maintained con-trol over the rear facing weapons.

For its war load the Kurowashi could carryjust over 7,257kg (8 tons) of bombs, about1,814kh (2 tons) less than the Boeing B-29.

The bomb baywas divided into two and eachsection could hold six bombs to give a total oftwelve. Beneath the main bomb racks were

OlleR AtRcnapr 129

hinged panels, one per side. Each panel heldfour bombs for total of eight. When the bombbay doors opened, the bombs suspendedfrom the panels would be released and thepanels swing aside so the remainder of thebombs could drop. This arrangement wascreated to maximise the payload space avail-able. Situated directly above the bomb baywere fuel tanks and it was likely the wingsalso housed fuel.

The Kurowashi used a tricycle landing gear

system with the nose wheel retracting intothe fuselage while the main landing gear

went up into the wings. However, becauseof the healy tail and to prevent damage tothe rear propellers while on the ground orduring take-off and landing, a large,retractable tail wheelwas fitted to the back ofthe fuselage.

For its crew the bomber had five men: pilot,co-pilot, bombardier and two gunners. Oneof the gunners served as the radio operator as

the radio station was situated in front of theupper gunner's position.

It may very well be that Allied intelligencewas aware of this design and it was also likelythat by 1944-1945, intelligence officers wereno longer taking aircraft illustrated in the'Dreams of Future Designers' section in Soramagazine at face value. The Kurowashiwas acreation that would have been very difficult toexecute in reality and may not even have

been feasible.

S-31 Kurowashi - data

Contemporaries

Daimler-Benz Schnellbomber mit DB P83 0ruppenmotor (Cerman,v)

Healy Bomber

Five

Powerplant Four24-c,vlinder.liquid-cooledX-engines,each

deleloping 2,500hp, each pair driung [vo, metal 3-b]aded contra-

rotating propellers

Type

Crew

Dimensions

Span

Length

Heighl

Wing area

32.82m

21.09m

5.88m

1.33.00m'

I 07,7fr

69.2fr

I 9.3ft

1.431.6ft,

Weights

Loaded i 7,850k9 39,352 tb

Performance

['lai speed

Cruise speed

Landing speed

Range

Ceiling

FuelWeight

690knyh

;89knth

145knh

5,900km

15,100m

8,000kg

429mph

366mph

9Omph

3,666 miles

19,540ft

17,636Ib

Armament

Eight 7.7mm machine guns and four 23mm cannons (see text for

anangemenl); up to 8,000kg (l 7,636 lb) of bombs

Deployment None, The S-31 Kurottashi was purell a paper, ii

not impractical, design in a magazine,

The Kurowashi depicted here is in the markings ofthe 2nd Chutai, 62nd Sentai. Historically, this unitoperated Mitsubishi Ki-21 (SaIlyJ, Nakajima Ki-49Donryt (Helen) and Mitsubishi K-67 Hiryn(Pegry)bombers.

zooI?Jo

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130 JnpaNEss Secnor PRorecrs: ExponnrnNtaL AIRcnarr oF rHE IJA AND IJN 1939-1945

It was difficult for the US and her Allies toacquire intelligence about the Japanese warindustry as far as HUMINT (HUMan INTelli-gence) was concerned. This was due to therelative difficulty associated with either turn-ing a Japanese source or inserting a foreignspy into Japan who was capable of avoidingdetection. Once it was broken, the PURPLEcode (as used by Japanese foreign offices)and the laterJN-25 code (as itwas labelled bythe US) used by the IJN provided a wealth ofinformation and intelligence, but humanintelligence and cipher cracking were only apart of the overall processes. One avenueused prior to the war was the gathering ofpublications such as books and magazines.Besides being relatively innocuous to pur-chase in Japan, such sources could beobtained outside of Japan and were thereforeeasier to gather. It was one such publicationissued just prior to the start of hostilities thatrevealed the T.K.19 to intelligence officers.

The illustration of the T.K.l9 appeared inthe April 1941 issue of the Japanese aviationmagazine Sora in a section entitled 'Dreamsof Future Designers'. The T.K.19 showed afuselage that was elongated and ovoid inshape. More interestingly, it showed a canopythat could be lowered to fit flush with the topof the fuselage thereby eliminating the drag ofa standard canopy. This same concept wasseen in the Russian Bisnovat SK and BartiniStal'-6, both of which were high-speed air-craft whose designers were seeking military

OrHrR Arncnanr

T.K.l9

applications for their charges. Each wing ofthe T.K.l9 showed what appeared to be threeweapon ports, totalling six machine guns orcannons. There were also ducts in each of thewing roots, ostensibly to cool the engine. Aradiator bath may have been located in thenose of the aircraft. Given the flush canopy,the T.K.19 may have used a system similar tothe Stal'-6 in which for take-off and landingthe canopy hood was hinged upwards andthe pilot would raise his seat. Whether theT.K.19 used a periscope vision system forthe pilot once in flight as was proposed in theSoviet Lavochkin LL fighter was not known.

Like many of the other aircraft in this sec-tion, the T.K.19 would later appear in theAmerican magazine Flight in the 25 Decem-ber 1941 issue. The description made nomention of the more striking features of theplane as described and shown in the Japan-ese magazine. Instead, the article, which con-tained no illustration, reported the T.K.19 wasof orthodox appearance save that the aircrafthad a twin row radial engine in the rear of thefuselage and was cooled via ducts. From this,a drawing evolved that took the basic shapeof the Japanese T.K. I 9 and made it more con-ventional, to the point that it bore a slightresemblance to the Curtiss P-40 Warhawk, aplane that first flew in 1938 and one thatJapanese pilots first encountered in combatin late 1941. The changes from the JapaneseT.K.l9 included doing away with the flushcanopy (providing a more standard style seen

The T,K,l9 depicted here is shown in the colours ofthe 77th Hiko Sentai during operations in Burma,t94t-1942.

in many aircraft), moving the wings higher upthe fuselage, adding pronounced wing rootfairings that extended from the nose of theaircraft to rear of the cockpit (the latter beingset behind the wings) and having a mainlanding gear reminiscent of the Brewster F2Abut with landing gear doors. No weaponswere shown but air intakes were illustrated inthe wing roots.

From reviewing the information, US intelli-gence made the assumption that the T.K.l9was a bona fide Japanese fighter that was inservice or was soon to be in service. Thus, itwas codenamed Joe after Corporal Joe Grat-tan, one of the team members responsible forassigning codenames to Japanese aircraft.The T.K.19 failed to appeare in Japanesesources despite remaining in US intelligencebulletins. It eventually became clear that theT.K.l9 was nothing more than a fictional air-craft and Joe was removed from future intel-ligence publications.

T.Kl9 - data

No infonnation, if ony, on the specif[cations arc auailable for the T,K,]9

Deplolment

None. The T.K,19 existed only as an illustration in a magazine.

zJ

OJ

.l\q

131

Japanese Missile andGuided Munitions ProjectsThe aim of tactical missiles, specificallyguided munitions, is to increase accuracy. Ittakes a considerable amount of conventionalbombs or torpedoes to strike a ship and inflictenough damage to cripple or sink the vessel.

Likewise, anti-aircraft cannons have to put asignificant amount of shells into the air tobring down a single plane. Another benefit ofusing missiles is the measure of protectionafforded to the user by way of range. A fightercombating bombers has to attack at such arange that his weapons are effective and

therefore within range of the defensive arma-

ment of the target. The fighter also has to con-tend with escorting fighters before he even

has a chance to press home an attack on the

bomber. The same is true of attacking ships.

To improve accuracy, a torpedo or dive-

bomber has to be close enough to the ship to

ensure a hit. Of course, this also puts the air-

craft in the uncomfortable position of beingwithin range of the many anti-aircraft can-nons and machine guns carried by the ship,

as well as attack by fighters providing coverfor the vessel. Guided munitions eliminatesome or all of these problems.

Without doubt, the undisputed leader inWorld War 2 missile development was Ger-many. Missiles such as the Fieseler Fi 103 (the

V-1), EMW A4 (better known as the V-2),Ruhrstahl-Kramer X-l Fritz X and the Hen-

schel Hs 293A were used operationally with ameasure of success. This was iust the tip ofthe iceberg. Many more designs came close

to seeing seruice or were in the latter stages

of testing at the war's end. Such weaponsincluded the EMW C2 Wasserfall, Rhein-

metall-Borsig Rheintochter, Henschel Hs I 17

Schmetterling, Ruhrsahl-Kramer X-4 and

many more. The US was not lacking in missileand guided munition technology of its own.Operational weapons included the ASM-N-2

Bat, GB-l/GB-4 and the VB-1 AZON (MimuthONly). Proiects included 'Little Joe' (intended

as a ship-borne missile to combatkamikazes), the McDonnell LBD-1 Gargoyle

Weapon Systems

and the JB series of missiles. Other Allies,

such as the British and the Russians, wouldnot spend nearly as much resources on the

subiect as did the Germans and Americans.The British would squander the potential ofthe Brakemine surface-to-air missile and stall

the Fairey Stooge while the Russians wouldonly test and reject the promising KorolevType 212A (built in 1937), waiting until the

close of World War 2 to revive its missiledevelopment work. In some cases the Soviets

used the fruits of German labour as theirbasis, for example, developing the R-1/SS-I

Scunner from the V-2 missile and the Type

1OCh from the V-1 flying bomb.An example of the greater accuracy of mis-

siles and guided munitions can be seen in the27 December 27 1944 mission flown by the US

to attack the Pyinmana rail bridge in Burma.Nine VB-1 AZON guided bombs were enoughto destroy a bridge that for two years previ-ously had failed to be hit by thousands of con-ventional bombs. Likewise, the Germanswere able to successfully attack shipping tar-gets using the Henschel Hs 2934 and Fritz-X

using less aircraft and with a higher hit and killratio than if the same attacks had been madeusing conventional bombs and torpedoes.

With these benefits in mind, it is not sur-prising that Japan also devoted considerableeffort to producing such weapons themselves(while Japan did receive some German mis-sile technology, it is unknown how much of itfound its way into the IJA and IJN missile pro-grams). Both the IJA and IJN funded the

development of missiles as a means to bothcombat the bombers that tormented the

homeland and to attack Allied shipping.

The Funryu (IJN)The Funryu ('Raging Dragon') was the namegiven to the IJN's missile program that com-menced in 1943. The initial study for the Fun-

ryu was conducted by the Kaigun GijyutsuKenkyujyo (Nary Technology Laboratory) butthree other groups would review the studysoon afterwards and thev were the Dai-lchiKaigun KOku Giiutsu-shd, Dai-Ni Kayaku-Sho

(2nd Bureau of Gunpowder) and the KureKosho (Kure Arsenal). Ultimately, it would beKlgisho that was given the Funryu project inearly 1944. To accomplish the task, Ktlgishoformed the Funshin Kenkyu-Bu (Rocket

Research Bureau) and was staffed with up to200 technicians led by a research team madeup of40 officers (all engineers and/or techni-cians) from the IJN. In all, Krlgishd wouldinvestigate and put forvrard four Funrlmdesigns.

The first was the Funryu 1 and the design

was an airto-surface missile (ASM) whosespecific role was anti-shipping. Funryu 1 wasmuch like a miniature airplane. The warheadcontained 882Ib of explosive and guidancewas via radio control. Testing of the Funryu Iwas conducted with the missile beingdropped from a modified Mitsubishi G4M

bomber. However, it was seen that themeans to effectively control the missile inflight would require a significant amount oftime to perfect and with the increase in US

bombing raids against Japan, it was decidedthat efforts should be directed towards sur-

faceto-air missiles (SAMs). Thus, the Funryu

I was shelved and was to be the only ASM ofthe Funryu family.

The Funryr-r 2 was to be a SAM built arounda solid fuel rocket using a radio guidancesystem. Despite three rocket motors beingavailable already (the Ro-Tsu, Ro-Sa andRo-Ta), it was decided that a new motor wasrequired. This motor was capable of produc-ing 2,400kg (5,291 lb) of thrust during its 3.5

second burn time. The shape of the missilewas relatively simple. Four wooden wingswere fitted to the body of the missile and eachwas equipped with an elevon (elevons con-

trol both pitch and roll). Four fins, making up

the tail, were fitted to the outside of the noz-

zle for the motor. This final shape and config-uration was a result of numerous tests ofvarious missile bodies and wing/fin arrange-

ments in a wind tunnel. The radio guidance

system was initially to consist of a single

transmitter but a second was fitted to ensure

a measure of accuracy. The first transmitterwas used for target detection while the sec-

132 hpeNEsE SEcnEr Pnorscrs: ExprRruElrrnl Alncnepr or rHs IJA aNo IJN 1939-1945

ond would control and steer the missile to thetarget. To maintain attitude, the Funryu 2 con-tained two gyrocompasses and 50kg ( 1 1 0 lb)of explosive was housed in the nose. Thebasic operation consisted of the Funryu 2

being launched from a rail set at an angle of80". Once launched, radio receivers fitted inthe wings would receive signals from theground transmitter, steering the missile ontothe target.

The war situation in 1944 was starvingJapan of critical war materials and Krlgishofound they were unable to obtain the neces-sary quantity of duralumin to build the Funrlu2 prototypes. It took theft from a warehouseto obtain the required metals. Using theabsconded material, a number of Funryu 2

missiles were constructed with one beingused for continued wind tunnel testing andthe remainder used for actual field tests, thelatter being conducted near Mount Asama(located near Ueda). Testing commenced inthe spring of 1945. The first launches of theFunryu 2 were unguided, conducted solely toevaluate the rocket motor performance andthe general flight characteristics of the mis-sile. In July 1945, the first test of the Funryu 2

n'as undertaken using the radio guidance sys-

tem. With IJN personnel in attendance, theFunryu 2 successfully lifted off from thelaunch rail and was directed towards aground target. Using the radio signals, theFunryu 2 was guided to within 20m (65ft) ofthe target when impact was made. Althougha direct hit was not achieved, the test wasconsidered a success. It was to be, however,the last flight of the Funryu 2 because the warended before any further launches could bemade.

The Funryu 2 was 2.2m (7.2ft) long, .28m(0.9ft) in diameter and had a span of .88m(2.9ft). Total launch weight of the missile was3i0kg (816Ib) and its maximum ceiling was5.000m (16,404ft). The maximum speed ofthe missile at full burn was 845km/h(525mph).

Even as the Funryu 2 was being investi-gated, a variant of the missile, the Funryu 3,

rvas proposed using a liquid fuel rocket inplace of the solid fuel motor. However, initialdiscussions on the new rocket engine led tothe conclusion that there was no time orresources available to study, design, con-struct and test such a propulsion method. As

such, the Funryu 3 was shelved.With the commencement of flight testing

of the Funryu 2, work got underway onanother SAM that was to be far moreadvanced. This missile was designated theFunrlu 4. Design work was carried out byengineers from Mitsubishi and from the Air-craft Equipment Factory of Tdky6, all based in

WEapoN Svsrrn'ts

a facility in the lzu Peninsula, west of Toky6,The Funryu 4 was to be built around the TokoRo.2 (KR10) rocket engine, the very sameengine used in the Mitsubishi J8M Slusuirocket fighter. As testing of the Toko Ro.2 wasalready underway and would soon be putinto production, Mitsubishi could devote less

time to engine concerns. The Funr1,,u 4 was touse a mixture of the Ko fuels (concentratedhydrogen peroxide) and Otsu (hydrazine

hydrate solution in methyl alcohol) as used bythe J8M. The engine would provide up to1 ,500kg (3,307 lb) of thrust and move the Fun-

ryu 4 to a maximum speed of 1,099km/h(683mph).

The guidance system selected for the Fun-rlr.r 4 was far more sophisticated than thatused in the Funryu 2. Whereas the latterrelied on radio, the Funryu 4 would use radar.Two stations would be used to deliver theFunryu 4 to the target. One station wouldtrack the target while the second would trackand control the missile. The intention wasthat the two radar signals would coincide onthe target, thus bringing the missile to impact.To control the missile, a radio signal of1,000MH2 was to be used with five frequen-cies. Each frequency corresponded to con-trolling the pitch and the roll with the fifthbeing the detonation command. A variationof this system is used today known at retrans-mission homing or Track-via-Missile (WM).

Funryu 4, like the Funryu 2, used two gJ,ro-

compasses and carried wing radio receiversfor the commands sent to it from the ground.

It carried a far heavier warhead of 200kg(4401b) in comparison to the 50ke (1101b)

warhead of the Funryu 2. The shape of theFunryu 4 was also more streamlined and itonly had two of the elevon-equipped wingsand two tail fins. Launch would occur from arail set at a 45'angle.

The Funryu 4 was 4.0m (13.1ft) long, .6m(1.9ft) in diameter and its span was approxi-mately.8m (2.5ft). Fullyloaded itsweightwas1,900kg (4,1891b), range 30km (18.6 miles)and ceiling of 15,000m/49,215f1.

Nagasaki Arsenal was tasked with buildingthe Funryu 4 and this did not begin until thelate summer of 1945. The first ground test ofthe missile and its motor commenced on 16

August, but the close of the war prevented theFunryu 4 from being launched or its guidancesystem fully tested.

To prevent the Allies from learning of theFunryu developments, the IJN forbade any ofthe personnel involved with the Funry'u fromdiscussing the project with anyone. In addi-tion, documents, test data, constructed mis-siles, the launching apparatus and thefacilities in which the Funrlu was developedwere all burned and destroyed.

The I-Go (IJA)While the IJN put its focus on SAMs, the IJA's

resources went into developing Air-to-Sur-face missiles (ASMs). The culmination ofthese developments, begun in 1942 by theKoku Hombu, was the I-Go series of missiles.The majority of the research on the I-Go wascarried out by Rikugun Kokugijutsu Kenkyujolocated in Tachikawa. Once the preliminarywork for the missiles was completed, theKoku Hombu reached out to Mitsubishi,Kawasaki and the Aeronautical ResearchInstitute of Tdky6 University to commencefinal development of the I-Go as they saw fit,using the initial data assembled by Rikugun.Sumitomo Communication Industry Co. Ltd.was the provider of the autopilot and thetransmitter/receiver system for the first two I-Go missiles with T. Hayashi designing the for-mer and K. Nagamori the latter.

The I-Go-1-A (Ki-l47) was the Mitsubishiversion of the I-Go. The final design of theKi-147 was completed by the end of 1943.

Work began on the missile using a basic air-plane configuration and its construction wasmade of wood and metal. It was propelled bya rocket engine built by Nissan Jid6sha KKwhich produced 240kg (529 lb) of thrust witha burn time of 75 seconds, providing a topspeed of 550kg (342mph). The warhead wassubstantial using 800kg (1,764 lb) ofexplosivetriggered by an impact fuse. Guidance was byradio from the carrying aircraft. The firstKi-I47 missiles rnere completed in 1944 andby mid-year unguided test drops had com-menced at Ajigaura, Atami and Shiruishi. Thecarrier aircraft lvas a modified MitsubishiKi-67-l HiryU bomber. By October 1944,

guided test drops of the Ki-l47 had begun.Despite the testing, the Ki-147 did not enterproduction and only fifteen were built. TheKi-l47 had a length of 5.8m (18.9ft), a span of3.6m (1 1.8ft) and a launch weight of I,400kg(3,086 rb).

The I-Go-1-B (Ki-l48) was the Kawasaki I-Go. Smallerthan the Ki-l47, the Ki-l48 used aHTP rocket motor that developed 150kg(331 lb) of thrustr,vith an 80 second burn time.The wings were constructed of wood whilethe body and fins were made from tin. As aconsequence of the smaller size, the war-head comprised only 300kg (661 lb) of explo-sive and it used a direct-action fuse. Forguidance, the Ki-148 used the same radio sys-

tem as the Ki- 1 47. Following wind tunnel test-ing with full- and half-size models, Kawasakiproduced a number of missiles at their Gifufactory for testing to begin in late 1944. Ki-148

test launches were made from four modifiedKawasaki Ki-48-ll Otsu bombers at Ajigaura inlbaraki Prefecture. By December 1944, up to20 Ki-l48 missiles were being launched per

133

week from the bombers. Despite the rela-

tively successful testing, the Ki-148 was neverput into production and total deliveries ofthe pre-production/test Ki- 148 missiles

amounted to 180. Had the Ki-148 gone intoservice, the Kawasaki Ki-102 Otsu was to be

the designated carrier aircraft.Ki-I48 had a length of4.1m (l3.4ft), a span

of 2.6m (8.5ft) and a launch weight of 680kg(r,499Ib).

The I-Go-l-C would be the final I-Go pro-ject. The Aeronautical Research Institute ofToky6 University decided to take a com-pletely different approach to guidance.Deciding that anti-shipping would be the

main use of the I-Go-1-C, the missile dis-pensed with the radio guidance method and

instead employed a novel system that used

the shockwaves produced by naval cannonsas the means to direct the missile. In essence,the missile would guide itself to the target bysensing the shockwaves developed in the airby large naval cannons during firing. Since

shockwaves travel outwards from the can-

non, the missile could determine directionand adjust its flight path accordingly to bringit onto the target. The main benefit of the sys-

tem was that the missile was a fire-and-forgetweapon. As long as naval ships engaged inbombardment, the I-Go-l-C would be able totrack and attack them on its or,r.'n. Testing ofthe system got under way in 1945 and the ini-tial results showed promise. However, the

missile body was never built as the warended before testing of the guidance hard-ware was complete. The proposed I-Go-1-C

was to be 3.5m (11.4ft) long with a diameterof l.6ft. Other specifications for the missile,

such as its warhead size, rocket motor, per-formance and weight are still unknown. The

I-Go-l-C is sometimes called the Ki-149 butthere is no evidence to support the use of this

name.Since the Ki-147 and the Ki-148 achieved

flight testing and both used the same radioguidance system, the procedures to launchand control the missiles were basically the

same. The Ki-67 and Ki-48 bombers used inthe testing were modified to accommodatethe missile operator as well as the equipmentneeded to guide the weapon. Operationally,the missiles would be dropped at an altitudeof 1,500m (4,922f1),1lkm (6.84 miles) fromthe intended target. By the time the missilewas 5km (3.11 miles) from the target, the alti-tude varied between 30m to 150m (98ft to492ft) depending on the preset of the altime-ter. The operator would guide the missile viaa joystick and just before it passed over the

target, the missile would be put into a dive,

bringing it down onto its target. The launchingaircraft had to remain within sight of the mis-

sile and in most cases would be 4km (2.5

miles) from the target when the missile hit.

While the handling characteristics of theweapons were found to be good, analysis

showed that the missiles tended to fall either300m (984ft) short of the target or 100m(328ft) past the target. The reason forwas thatthe operator had to rely on his own vision and

clear conditions in order to guide the missile.

He was not provided with any form of special

optics nor did the missile carry a means tomark itself in flight such as using burningflares or smoke which the operator could use

to maintain sight of the weapon. The onlymeasure of this kind ever employed was a taillight which was used at night so the operatorcould track the missile. Had the Japanesegiven further consideration to the operator'sneeds, accuracy may have been improved. Afactor against the use of the Ki-147 and Ki-148

was that the launch aircraft had to be withinllkm (7 miles) of the target and had toremain in the area to proceed with the attack.With the heavyAllied air presence, getting tothe launch range would have been a formi-dable task and this may have been a factor inthe Ki-147 and Ki-I48 failing to enter service.

OTHER SYSTEMS

Kurai Aerial Torpedo No.6/No.7In April 1944, the IJN initiated a design for anair dropped, anti-submarine torpedo. Whilenot a true guided weapon, what made the

design unique was that the torpedo waswinged and once in the water, entered a cir-cular pattern as it dived down. Work on the

torpedo was carried out by the First TechnicalArsenal Branch at Kanazawa under Com-mander Fukuba. The torpedo body wasmade of wood with the exception of themetal nose. The torpedo had no means ofpropulsion, either for flight or in the water.The wooden wings, each 1.5m (4.9ft) inlength, were glued to the main torpedo bodyat a 20' upward angle. The wing span wasapproximately .9m (2.6ft) and the nose car-ried a 100kg (2201b) warhead and the totalweightwas 271kg (5971b). The wood rudderswere fixed at an 8o angle which, once in thewater, imparted the counter-clockwise circu-larpath. The rudderwas coveredwith awoodfairing to stop it affecting the freefall glide ofthe torpedo. Once the torpedo entered the

water, the aluminium pin holding the fairingon sheared off and the fairing came free.

The first tests were carried out to evaluate

the gliding properties of the torpedo. In all,

forty drops were made of which fifteen werecomplete failures, the torpedo tumbling orspinning out of control. The wings were mod-ified according to the specifications given

above, resulting in the Kurai No.6 whichimproved the gliding ability but not to a satis-

factory level. Underwater testing was con-ducted by releasing the torpedo from a boatand the results showed a 17' dive angle at a

speed of 5-6 knots. Colour dye released fromthe nose of the torpedo assisted the evalua-tors in determining how the weapon workedunderwater. The maximum depth the tor-pedo could reach before the pressure over-

came it was 100m (327f1). From the tests, itwas determined that a form of gyrostabilisa-

tion would be required.The designated carrier plane for the Kurai

was the Nakajima B6Nl and B6N2 Tenzan(known as JrI1 to the Allies). No modificationof the plane's torpedo rack was required. In

operation, the pilot had to visually sight the

target and release the torpedo from a heightof 100m (327fr). An air spun vane would armthe weapon after it was released and the tor-pedo would go into a 20o downward glide.

Once in the water, it would enter its circulardive with a diameter of 79m (260ft), makingone revolution through a depth of 79m (260ft)

after which it would continue to circle and

dive until it was crushed under pressure orhad struck the submarine before reaching100m (327ft). A magnetic proximity fuse wasto be used on the torpedo.

In all, 100 of the Kurai No.6 were built withmany of them expended in testing. Kugishd

constructed the rudders and the metal com-ponents (nose and wing braces) while theMarunimoko Company (located in Fut-sukaishi, Hiroshima Prefecture) producedthe torpedo body and wings.

The poor results of the Kurai No.6 resultedin slight modifications to the design. The wingspan was increased and the rudders madetaller and set at 6'rather than 8', and the nosewas thickened to enhance the ability of the

torpedo to penetrate a submarine hull. Thisnew model was designated the Kurai No.7

and in January 1945, eleven test drops weremade, but the weapon showed little improve-ment over the Kurai No.6. The end of the warbrought the entire proiect to a close, the engi-neers having run out of time to solve the poorgliding performance and finalise the special

fuse.Two Kr-rrai No.6 mock-ups were captured

and shipped to the US for delivery to TAIC.

What their fate was is unknown.

The Ke-GoAs the war progressed the Japanese came tosee the invasion of the home islands as averyreal threat and various means of attacking theinvasion fleet were investigated. One possi-

bilitywas abomb capable of homing in on theheat emissions of naval vessels. The plan

lB4 JnpnrvEst SEcner Pno.rncrs: ExpsRr[4eNral ArncRnrt on rnE IJA eNo IJN 1939-1945

called for the bombs to be used in nightattacks when heat signatures of the ships

would not be masked by the sun and otherambient heat sources. The project wasundertaken by the IJA and given the name Ke-

Go and work commenced in March 1944. TheFirst Military Arsenal's Omiya Department inTdkyo undertook development of the

bolometer that would detect heat in theinfrared wavelength and bench testingshowed that the mechanism was workable.In fact, the sensor could detect the heat froma man's face at 100m (328ft)! For the bomb tocarry the bolometer, three different tl,peswere investigated: the B-1,8-2 and B-3. Of thethree, only the first showed potential and theremainder rn'ere abandoned. A myriad ofmen and departments were assigned to thetask of realising the B-1. Under the MilitaryOrdnance Administration Board was MaiorFujita who oversaw the gyro and airframe,\'lajor Hizuta who also worked on the air-frame research, and Major Sonobe whoaddressed the amplifier. The Seventh MilitaryLaboratory encompassed Professor Konishiof the Shikan Gakkd in Osaka who handledthe mathematicalwork, Professor Sano of theOsaka Imperial University who conductedthe electrical design and Dr. ltakawa of theAeronautics Research Laboratory whoundertook the aerodl,namic design studies.All wind tunnel testing was held at RikugunKokugijutsu Kenky'ujo.

The first two bomb versions, the Ke-Go 101

and 102, were built in small numbers: ten andfive respectively. The hydraulic and mechan-ical linkages for operating the bomb ailerons,coupled with the use of an electric gyro thatinterfered with the bolometer (A bolometer is

a device used to measure the energy of inci-dent electromagnetic radiation and wasinvented by Samuel Pierpont Langley in1878.), saw both of these versions aban-doned. Continued study resulted in the Ke-Go 1 03, I 04 and 1 05. However, none of thesedesigns left the drawing board although the103 was to use an air gyro instead of an elec-trical version. The gyro only existed to ensurethe bomb did not spin faster than 360'in 50

seconds. The Ke-Go 106 would be the first tobe built in numbers, fifty examples in all.Overall length of the 106 was 4.7m (15.5ft)

long and the wing span was 2m (6.5ft). Fourmain fins were fitted 1.7m (5.7ft) down thelength of the bomb body with a smaller set offour fins 1.2m (3.9ft) behind the main fins,and the tail of the Ke-Go contained divebrakes. In the nose was the bolometer whilethe shape charged warhead was containedbehind it. Two strikers that protruded outfrom the nose were tipped with small pro-pellers which spun and armed the bomb after

Wnnporu SvsrsN,ts

release. The strikers seled as the impactfuse, but a delayed fuse was also installedshould the bomb strike water, in which case

it would explode beneath the waterline of aship. In short order, the Ke-Go 107 joined theprogram with a total of 30 bombs. The 107

had similar dimensions to the 106 version andweighed 726kg (1,600 lb).

The Ke-Go was guided in flight by the

bolometer. The bolometer was part of a unitthat consisted of the bolometer itself, a mir-ror, motor, distributor, amplifier, relay boxand battery. Heat sources passing through the

bolometer would strike the mirror that,

depending on where it struck, would trigger

ihe amplifier which operated the ailerons,steering the bomb towards the heat source.The use of dive brakes slowed the plummetof the bomb, allowing time for the bomb tomake adjustments in flight before impact.The ailerons could move up or down 20'. Forawarhead, the Ke-Go caruied between 200 to300kg (440 to 661 lb) ofshaped charge explo-sive, depending on the model. Perhaps inerror, a 1946 US Naly report lists the warheadas ranging from 20 to 30kg (44 to 66lb) ofexplosive which is very light for the size of theKe-Go.

With enough bombs ready and available,field testing began without the bombs con-taining any payload. The test used a floatingraft which measured 10m (32.8ft) by 20m(65.6ft) and was anchored in LakeHamanako (located in Shizuoka Prefecture).On the raft wood and coal in a 4m (13ft) by4m (13ft) pile was set alight. Both Ke-Go 106

and 107 bombs were released from altitudesvarying between 1,524m (5,000ft) and 3,048m(10,000ft) but the results proved very disap-pointing. In all, around 60 drops were madebut only 5-6 of the bombs displayed the zig-

zag flight path that indicated the bolometerwas sensing the heat from the fire and guid-

ing the bomb. The remainder simply veeredaway from the raft. The dismal results wereblamed on faulty equipment although thedata collected was not sufficient to properlyidentify the cause of the failures. It was foundthat the terminal velocity of the Ke-Go107was 539km/h (335mph). In July 1945, furthertesting ceased, though work continued onimproving the bomb.

The Ke-Go 108 was developed but it waswith the Ke-Go 109, the last to be designed, inwhich the Japanese hoped the problemswould be resolved and the bomb wouldfinally prove successful. The Ke-Go 109 bombwas 5.5m (18ft long), 5m (1.6ft) in diameter,had a wingspan of 2.9m (9.4ft) and weighed800kg (1,7641b). It was estimated that the ter-minal velocity for the Ke-Go 109 was 579km/h(360mph). lt featured a larger wing span

because the smaller span was considered tobe one of the main causes of the poor perfor-mance of the Ke-Go 106 and 107. Itwas antic-ipated that the 108 and 109 bombs would be

ready for test drops by September 1945. Ofcourse, the end of the war ensured this wouldnever happen and neither bomb was built.

Had the Ke-Go made it into service, the car-

rier was to be the Ki-67 Hiryu (codenamed

Peggy by the Allies). The bomb required aspecial brace that was fitted into the bombbay, the apex of the brace extending a fewinches past the exterior of the doors. The

bomb was secured to this and the lower wingcould fold to give ground clearance. On take-

off, a crewman had to lower the wing and didso by means of a crank that activated a servoin the bomb, which then moved the wing.The bombardier would use bombing tables

appropriate for the weight of the weapon and

on release the bomb's arming wires werepulled out along with a wire that released the

dive brakes. Typically, the bomb would be

dropped from 2,000m (6,562f1). After the

bomb was away, the Ki-67 saw a 64km/h(40mph) increase in speed.

All of the bombs were built from wood. The

only metal components consisted of the nose

cap containing the bolometer and the divebrakes. In all cases, the bomb bodies werebuilt by the Atsu Department of the NagoyaArsenal, the gyroscope by Hitachi Co., the

spring/gear parts for the timing mechanismby the Hattori Jewellery Co. and the electricalcontacts for the timing mechanism by Sumit-

omo Communications Branch.Interestingly, the US would develop a simi-

lar weapon, the VB-6 Felix. This was a 454kg(1,000|b) bomb fitted with an infrared seekerin the nose that controlled the fins and guided

the bomb. It was meant for night warfare,notably against ships at sea. The VB-6 was putinto production in 1945 but would not see ser-

vice by the close of hostilities.

135

1;::11lir;liis:

zooEF

ogzzo

From left to right, the Funrt'u 2, FunrSr 4' Ki-147'Ki-148, and the Ke-Go.

JapexrsE SrcRer Pnorncrs: Expsnrl,tnnrel Atncnanr oF rHE IJA AND IJN 1939-1945136

Specialised Bombs

Both the IJA and the IJN developed spe-cialised bomb munitions during the war,some of which remained projects while oth-ers saw service. Several were dedicated to thepractice of air-to-air bombing in which bombswere used to attack enemy bomber forma-tions. Although not a complete list, the follow-ing are some of the more interestingexamples.

Ko-DanThe Japanese expended some effort in devel-oping the Ko bomb. This was developed inresponse to obselations made by oneKobayashi of high-speed photographs of det-onations of various experimental shapedcharges. The basis of his theory was that theenergy produced by an explosion is projectedalong horizontal lines with the impact sur-face. By extension, the amount of energy cre-ated is proportional to the quantity of theexplosive used. To achieve a wider impactarea against a target, the Ko bomb had a 2mmthick rubber nose that was mated to a 2mmthick steel case. On impact the nose of thebomb would flatten and expand, therebyenlarging the surface area and increasing theeffects of the explosive pellets containedwithin. The Ko would be used against hardtargets such as concrete emplacements. Intests, a Ko bomb with 50kg (1101b) of TNTand ultropine in an even split mixture couldpenetrate a lm (3.2ft) slab of concrete andutterly destroy it. lt would take a regular 25Okg(551 lb) bomb to accomplish the same effect.A part of this concept is known as the Misz-nay-Schardin Effect and is in practice todaywith modern HESH (High Explosive SquashHead) munitions and EFP (ExplosivelyFormed Penetrator) weapons.

Mk. 7 (rJN)Conceived around 1936 by Dai-lchi KaigunKOk[ Gijutsu-sho, the Mk. 7 chemical bombwas not given priority since at the time therewas little need for such a weapon and it wasthought the work needed to bring it to fruitionwould be too great. The idea surfaced nearthe end of thewar, the Mk.7 then being denieda second time in favour of guided missiles.The design was based on the l kg (2.2 lb) prac-tice bomb. It had a rubber nose and within a

special tail was a glass bottle of Bacillus bac-teria, most likely B. anthracis, which causesanthrax. It had no fuse or explosive charge,the impact being enough to break the bottleand release the bacteria. The planned colourfor the bomb was a purple nose with a purpletail.

MK.I9 (IJN)This was an air-to-air rocket-propelled bombdesign intended for use against bomber for-mations. It weighed 7.5kg (16.5 lb). Although itwas never built, the work eventually resultedin the Mk. 28 rocket bomb.

'Silver Paper Scattering Bomb' (IJN)This was the Japanese version of the GermanDiippel, better known as 'Window'. A 2kg(4.4Ib) sheet steel cylinder was packed with200 pieces of metal coated paper measuring.3mx 8.4m (lftx 27.5ft). The bomb used a pullfuse that the crewman yanked to arm it andwas then thrown out of the aircraft, the sub-sequent charge expelling the papers into theair to act as false radar targets. This anti-radarweapon was used heavily from 1944-1945.

To-3 (IJA)Developed and produced from l94l to 1942,the To-3 was a cluster munition and initiallydesigned to combat aerial targets. However,the To-3 turned out to be more effectiveagainst ground targets. Thirty to forty To-3bomblets could be carried in a dispensingcontainer or modified underwing bomb rackscould carry several of the To-3 bomblets.Once released, either from the container orthe rack, the To-3's vane would spin, armingthe munition. Use of the To-3 was performedon a limited basis and production ended in1942.

Ta (IJA)Evolving from the To-3 was the Ta. Each Tabomb was a 40mm hollow charge weighing.33kg (.741b). It used fixed tail fins. Whenattacking airborne targets, canisters contain-ing between 30 and 76 of the Ta bombs wouldbe released. A burst fuse would open the can-isters, usually just after release, to scatter theTa bombs. The loaded canisters weighed30kg (66 lb) and 50kg (1 I 0 lb) respectively andthe Ta was first used operationally in 1943

with Japanese pilots claiming a number ofkills using the weapon. Typically, the Ta wasfar more effective when used against moredensely packed bomber formations.

Ta-105 (IJA)The Ta-105 came from the need to attackAllied shipping during the expected invasionof Japan. The Ta-105 was the Ta bombletenlarged to carry a more substantial payload.The bomblet had a 100mm hollow charge thatwas capable of penetrating up to 140mm ofarmour plate. Unlike the Ta, the Ta-l05 usedfolding tail fins that deployed upon release.Each canister contained 21 Ta-105 bomblets.

WEnporu Svsrrl,rs 137

Type 2 No.6 21-Go Model I (IJN)This munition was the IJN's version of the T

mb to a maxi-

Type 5 No.25 Mk.29 (IJN)Designed for use by special a

together, each cluster weighed 50kg (1 10 lb)and the average single engine fighter couldcarry up to four clusters. The usual tactic wasto drop the To-2 bombs into the path ofoncoming bombers. To increase the depth ofthe bomb spread, some To-2 bombs had asmaller parachute that would result in a fasterdescent. The bomb was armed with animpact fuse that, regardless of where thebomb struck, would trigger the detonation.Usually the cable would be hit by the bomberwith the bomb swinging up and against theplane, exploding the bomb. The To-2, how-ever, was not developed further because thecable was typically cut if hit by a wing, it reliedon a high altitude to be effective and the Tamunition showed far greater promise.

lt was a heavier bomblet and weighed lk the Mk.29 contained 1,100 packed in(2.21b). A canister would carry up to 40 of theModel I bomblets. Like the Ta, a fuse wouldopen the canister deploying the bombletsonto their target.

(110lb) of whi After fly-

formation, the pilot would

Type 2 No.6 2l-Go Model2 (lJN)This was the same bomblet but instead of thehollow-charge in the Model l, the Model 2

used a solid black powder charge. This

change was made because the IJN felt that an

armour piercing charge was not necessaryagainst aircraft that were typically unar-moured. This did, however, raise the weightof the Model 2 and a canister could only hold36 of the bomblets, the total weight of theloaded canister being 49kg (1 08 lb).

Type 3 No.6 Mk.3 Model I (lJN)This was basically a simplified Type 99 No.3

Mk.3 bomb as it used a wooden nose and didaway with the impact fuse. The bomb was 1 m(3.3ft) long and weighed 56kg (1241b). Itsdesign commenced in 1943 and entered ser-

vice in 1944. Colouration was the same as theType 99.

Type 3 No.6 Mk.27 Model I (IJN)Development of this anti-bomber rocketbomb began in January 1944. The cone-shaped nose contained 140 iron pelletsembedded in 4kg (8.8lb) of white phospho-rous. A 1Okg (22 lb) propellant charge movedthe bomb to a velocity of 270mlsec(885.8fVsec). On detonation the pellets werescattered in a 60" radius and the bombwas provided with the fittings for rail launch-ing by fighters. The IJN accepted it forselice in February 1945 and final testing wascompleted in April 1945. Testing was con-ducted by DaiJchi Kaigun Koku Gijutsu-sh6,the Second Powder Factory Arsenal, andKashima Bombing

) long and

Type 3 No.6 Mk.28 Model I (IJN)

Using the Mk.19 as a basis, the Mk.28 was a fired like a rocket, there was no longer a

, anti-bomber rocket bomb with a . requirement to be above the intended targetin order to use the weapon. Luckily for theAllies, the Ro-Ta was still in developmentwhen the war ended.

warhead A pro-pellant chargemum velocity of 1,3l2fVsec. Dai-lchi KaigunKdk[ Gijutsu-shd built the bomb and its

clearence testing was undertaken by Dai-lchiKaigun Kokrl Gijutsu-sho, the Second PowderFactory Arsenal, and Kashima BombingExperimental Field. Testing was completedlate in 1944 but the rocket bomb was notaccepted for service. Its length was .7m(2.3ft) and weight 7.3kg (16Ib).

rng

aircraft,

use a pull cord to detonate the bomb while itwas still attached to the aircraft. The bombcould also be released where the tail fuse

would trigger the bomb explosion. Unlikeother pellet dispersing munitions, the Mk.29

flung them at right angles to the bomb casinginstead of in a downward cone. Initial testingwas begun in 1944 but only one prototype wasair dropped and the type did not enter service.The Mk.29 was 1 .6m (5.1ft) long and weighed2s0kg (551 lb).

Type 99 No.3 Mk.3 Sango (lJN)Designed in 1938 and entering service in 1 939,

this anti-bomber bomb contained 144 whitephosphorous-filled steel pellets. Its tail finswere offset to impart spin as it fell and thisarmed the tail fuse. The fuse would then trig-ger a burster tube down the middle of thebomb, scattering the pellets. A charge in thetail ensured the pellets were directed down-wards. Should the tail fuse fail, an impact fuse

was proved in the nose of the bomb. A latermodification of the bomb added fins to thebody to impart a faster spin. For identificationpurposes the nose of the bomb was paintedsilver and the fins red. The bomb was .7m(2.3ft) long and weighed 34kg (74lb).

Ro-Ta (IJA)

One of the problems the Japanese had withusing cluster munitions was that they reliedon the attacker having a higher altitude thanthe target in order to rain the bomblets downupon them. However, manyJapanese fightersstruggled at the altitudes at which the B-29s

usually operated. The IJA sought to solve thisdilemma with the Ro-Ta. The same Tabomblets were used but the canister wasessentially a rocket that was launchedtowards the target. A timed fuse would triggeran explosive charge that scattered the Ta

bomblets. In effect, the Ro-Ta was like a buck-shot shotgun shell. Because the Ro-Ta could

To-2 (lJA)Even before the To-3 and Ta series of clusterbombs, there was the To-2 parachute bomb.Developed in 1935, the To-2 was a 1 .8m (4lb)bomb that was suspended from a length ofsteel cable that was itself connected to a silkparachute. Ten To-2 bombs were clustered

138 JepafrEss SEcRrr PRorecrs: ExpeRrupntel AtRcRrnr or rHE IJA alll IJN 1939-1945

Specialised Bombs: Fu-Go

Japan was able to achieve where Germanyfailed and that was to bomb the US mainland.On 9 September 1942, the Japanese subma-rine I-25 surfaced west of Cape Blanco, Ore-gon, and a single Kugisho E14Y1 floatplane(known as Glen Io the Allies) was assembled.Pilot Warrant Officer Nobuo Fujita andobserver Petty Officer Okuda Shoji climbedinto the plane that was loaded with two 77kg(l 70lb) incendiary bombs and took off for theUS coast, heading towards the Oregon side ofthe Siskiyou National Forest. Once over theforest, the bombs were released in the hope aforest fire would start. However, recent rains

coupled with the bombs having beendropped too low resulted in a few small firesand these quickly put out. The attack wouldbe repeated again on 29 September 1942 butonce more the results were disappointing.The first attack marked the only time in historyan enemy aircraft bombed the US but anotherplan was in the works, one far more ambitiousand ingenious, but ultimately fruitless.

The plan was called the Fu-Go, 'Fu' beingthe first kanji of the word 'fusen', meaning bal-loon. The 'Go' simply meant tlpe. Originallyconceived in 1933 by Lieutenant General Rei-

kichi Toda of the Japanese Military ScientificLaboratory, the bomb dropping balloon Fu-Go

rvas part of a series of studies into possible

new weapons. Erperiments with balloonscapable of maintaining a stable altitude wereinitially allowed to proceed but by 1935 the Fu-

Go projectwas cancelled. However, followingthe famous Doolittle raid on 8 April 1942, theFu-Go was revived as a means of exacting ret-ribution for the attack.

The Fu-Go was to have been launched fromsubmarines situated 998km (620 miles) offthe US coast. In March 1943, a 6.1m (20ft)

diameter balloon was successfully launchedand remained aloft for at least ten hours,enough to make the submarine launch planrvork. The main problem was the effect oftemperature on the hydrogen gas used in theballoon. At night and in cool temperatures, thegas pressure was reduced and the balloon lostbuoyancy while by day, in higher tempera-tures, there was the risk of the gas expandingand rupturing the gas envelope. Because ofthis launches of the balloons had to take placeeither by day or by night and not straddle thehvo times of day. However, the IJN's need forsubmarines to support operations in thePacific left no room for launching the Fu-Go

and the projectwas again cancelled inAugust1943.

Remaining undeterred, the Fu-Go engi-neers looked into a solution where the bal-loon could be launched from Japan, although

Wsnporu SvsrEus

it would now take 50-70 hours for it to traversethe Pacific Ocean and arrive over the US

mainland. General Sueyoshi Kusaba was putin command of the project to tackle the dis-

tance issue and put the Fu-Go into operationaluse.

To overcome the problem of maintainingaltitude as the balloon travelled by day andnight, a ballast mechanism was designed.This consisted of a cast aluminium ringaround which 322.51o3.2kg (5.5 to 7lb) sand-bags were secured. Fuses were fitted to pairs

of sandbags, the fuses powered by a smallbatteryand connected to aneroid barometers.When the balloon sank to an altitude ofaround 9,144m (30,000f1), the aneroid barom-eter would trigger a switch. In turn, this trig-gered a fuse which in turn would fire twosmall charges that would each release a sand-bag, one across from the other to maintainbalance. The balloon would then rise to analtitude of around 11,582m (38,000ft) where a

gas release valve set into the bottom of theenvelope discharged some of the gas to keepthe balloon from rising higher. Eventually itwould drop again triggering another release ofsandbags followed by a rise, vent and thecycle would repeat. By the time the last pair ofsandbags was dropped, it was estimated thatthe balloon should be over the US mainlandwhere its destructive payload would then bereleased.

The balloon could lift a maximum of 136kg(300Ib) at 9,144m (30,000ft). The typicalmunition payload was one Type 92 15kg(33 lb) high explosive bomb, one Type 100 Skg

(11 lb) incendiarybomb and one Type 97 12kg(26.4Ib) incendiary bomb. A 29m (64ft) fuse

was connected to a charge on the gas enve-lope and once the bombs were dropped,the fuse was lit which, in turn, destroyed theballoon.

The spherical gas envelope could store538m'(19,000ft') of hydrogen gas. The diame-ter at full inflation was 10m (33ft). Early gas

envelopes were constructed from rubberisedsilk but this was too costly to construct and theproduction Fu-Go used Washi paper madefrom the kozo bush. While Washi was inex-pensive and already produced by hand inpaper mills across Japan, there was no meansto ensure a constant level of quality. There-fore, the Fu-Go program had to developmechanical methods to make Washi as wellas laminate it. It took four to five layers ofWashi to make a gore (a segment) and 38 to

64 gores glued together to make the sphere.The adhesive used, called konnyaku-nori,was made from konnyaku, a potato. As theglue was relatively clear, colouring was addedso workers could check for evenness in theapplication. The glue also served as a sealant

to prevent gas leakage as the untreated Washiwas porous.

After being brushed with the glue, eachgore was inspected for flaws. This was doneby laying the gores over a panel of frostedglass beneath which was a light. The glue

would appear blue and any uneven applica-tions of the glue showed up as a lighter area.

All flaws were marked and patched. Once thegores had passed inspection, they were takento the final assembly area. A large room wasrequired with sharp objects padded so not torip the gas envelope. High school girls wereoften employed for assembly, using the glue

to affix the gores together to create the com-pleted gas envelope. Each girl had to ensureher nails were trimmed, that she wore gloves

and socks, and that she did not wear hair pins

as these could damage the gas envelope.

Once the envelope was finished, it was takento another building, often a sumo hall or the-

atre (buildings specific for the task were laterbuilt), and inflated to check for leakage. Aftersuccessfully passing the final inspection, theFu-Go was completed.

The finished Fu-Go had a scalloped waist-band around the gas envelope to which the 19

shroud lines, each 14m (45ft) long, weresecured. The lines were brought together and

tied into two knots from which the bombs and

the ballast system were hung.With the problem of keeping a relatively sta-

tic altitude solved, the next hurdle was todetermine where and when to launch the bal-loons. Towards the close of 1943 and into theearly part of February 1944, the Japaneselaunched balloons equipped with radioswhich were tracked so their courses could bemonitored. Two stations set up in Hokkaidoand in Chiba Prefecture could track the bal-loons only through the first portion of theirflight, but once over the open ocean all con-

tact was lost. The Japanese were aware thatthe west-to-east wind speeds were at theirpeak from November through to March, top-ping out at 298km/h (185mph). In addition, a

shortage of meteorological data on weatherpatterns over the ocean and at high altitudeslimited the ability to plan trajectories for the

balloons. While the winds were higher, it wasalso winter throughout most of the launchwindow. In addition, the balloons had to bereleased in clear, cloudless weather with littlesurface wind. If balloons were sent up in over-cast skies with precipitation laden clouds,moisture would collect on the balloons whichwould freeze at higher altitudes, addingweight resulting in the balloons being unableto reach the US. Three major launch sites

were selected: Nakoso (Fukushima Prefec-

ture), Otsu (lbaraki Prefecture) and lchinOmiya (Chiba Prefecture).

139

On 3 November 1944, the Fu-Go balloonbombing campaign was officially opened. Inall, between 9,000-10,000 balloons were avail-able and by 20 November, the first en masselaunchings had taken place. Prior to launch,the sandbag release mechanism was set

based on the estimated wind speeds toensure the balloon was over the US beforereleasing its payload. The gas envelope wasonly partially filled to allow for expansion ofthe hydrogen at an altitude of 4,877m(16,000ft). On a good day crews could launchup to 200 balloons. March 1945 would see thehighest number of balloons deployed, 3,000 inall, and the final launch was made on 20 April.Typically included in batches of balloonlaunches would be a radio equipped balloonto allow for tracking.

The first balloon was found on 4 November1944by a US Nary patrol boat. It had crashedinto the sea 106km (66 miles) southwest ofSan Pedro, California. Nothing much wasmade of it until another turned up in the sea

two weeks later. Also, balloons were found upin Montana and Wyoming and the US militaryrealised the purpose of the balloons. Federaland state agencies were put on alert (espe-

cially forest services as the threat of forest firesfrom the incendiaries was very real) and steps

were taken to prevent news of the balloonbombs reaching the general public. This wasdone to prevent panic in the populace sinceno one could be sure when or where a bal-loon would release its bombs. In addition, bykeeping the story from the press, the Japanesewould be denied any information on theeffectiveness of iheir attacks. The censorshipwas very effective and only one story con-cerning a balloon bomb was publishedappearing in Thermopolis in Wyoming. Thiswas also reported in a Chinese newspaper.From this, the Japanese judged the Fu-Go

campaign was a success and the ballooncampaign continued.

The near total shutdown of public informa-tion on the balloon bombs had one severedrawback for the Americans and that was thatthe public had no knowledge of their exis-tence and consequently were not be warnedof the dangers. The censorship would bereversed after an inevitable tragedy occurred.On 5 May 1945, near Bly, Oregon, Reverendfuchie Mitchell, his wife and five childrenfrom his church group were enjoying a picnicin a wooded area. One of the children, JoanPatzke, found a balloon stuck in a tree andtried to pull it down. The subsequent explo-sion of the bombs it carried killed all but Rev-

erend Mitchell. The deaths rvould be the onlyUS mainland casualties from enemy action.Following the incident, the censorship waslifted to ensure public safety.

The Fourth Army Air Force was tasked rviththe detection and interception of the balloons.In addition, Project Firefly was initiated toposition aircraft and troops to respond to for-est fires. Project Lightening was set upthrough the Department of Agriculture to beon alert for biological attacks against cropsand livestock. Successful interception of theballoons proved difficult owing to the highalti-tudes at which they travelled, poor ground

reporting and inadequate weather reporting(this would also hamper the ability of the US

to accurately determine launch points fromJapan). In fact, only two Fu-Gos were shotdown over the US mainland. Only US Armyand US Navy assets in the Aleutian Islands hada higher tally as the balloons often passed overthe territory. With the problems in locating theballoons, a final plan, Project Sunset, was ini-tiated to create a web of radar sites across thecoastline of Washington State. When balloonswere detected, interceptors would be scram-bled to engage them. As it turned out, the planwas put into action in April 1945, the samemonth the Japanese ceased launching the Fu-

Go. In any case, radars had a difficult time indetecting the balloons due to their low signalreturn.

The cost to produce one Fu-Go was approx-imately 10,000 yen. If the added expense ofthe design and production of the mechanicalequipment to produce Washi and the erec-tion of buildings to inspect the balloons, theprice of the Fu-Go project was high in com-parison to the results it brought. Still, Japanesepropaganda broadcasts played up the Fu-Goprior to the project being cancelled in April1945.

Ironically, on 10 March 1945, a balloon fromone of the last launchings struck a power line,resulting in the loss of power to the nuclearplant in Hansford, Washington. This plant cre-ated ihe atomic material used in the Manhat-tan Proiect's atomic bombs, which wouldultimately be used against Japan. The loss

was barely noticed as back-up systems cameonline to maintain the reactor. Another ironyoccurred on 13 March 13 when two Fu-Gos

returned to Japan, although they toucheddown without causing any damage.

In all, 296 balloon sightings or incidentswere reported across 17 US states, 5 Canadianprovinces and Mexico out of the 9,000-10,000

launched. Hundreds remain unaccounted forand even today, some may still lurk in unpop-ulated areas or in dense forest presenting a

danger to anyone encountering one.Interestingly, the British would use a similar

weapon against Germany. Called OperationOutward, hydrogen filled balloons equippedwith a trailing steel chain to short out powerlines and three 6lb incendiary devices to trig-

ger forest fires rvere launched from two sites

in England on 20 March 1942. The balloonswere of simple construction, reached a heightof 4,877m (16,000ft) and inexpensive at 35

shillings each. More of a nuisance to the Ger-

mans, the greatest triumph of the operationwas the explosion of the Bohlen power stationcaused by the failure of an overload switchwhen a balloon struck a main power line nearLeipzig. The last launch was made on 4 Sep-

tember 1944.

Post-war, the US would use Fu-Go technol-ogy in the E77 balloon bomb project.

The illustrations depict the following weapons,from left to right: canister for the Ta bomb with aTa bomb beside it, Ko-Dan rubber bomb, Type 99No.3 Mk.3 Sango and the Fu-Go.

140 JnparussE Socnlr Pno:Ecrs: ExpERruENrar- ArRcRnnr op rHE lJA,qNl IJN 1939-1945

1#

141WeapoN SvsrEus

Appendix

German Technical Exchange\Mith Japan: A Brief OverviewIt should not be surprising given Japan wasallied to Germany as part of the Axis powersthat there were numerous requests for andthe exchange of war materials between thetwo countries. What was perhaps surprisingwas that the bulk of the exchange would go

one way with very little going in the oppositedirection.

Japan's relationship with German aircraftand manufacturers went as far back as

1915 when the Isobe Kaizo Rumpler Taube,a copy of the Taube aircraft, was built andflown by the Imperial Flying Association.In the 1920s and 1930s, Heinkel and Junkerswere the dominant German firms, both ofwhose designs were much in demand bythe Japanese. Other German firms such as

Dornier, Rohrbach and Hansa-Brandenburgalso sought to make sales prior to thestart of World War 2. Before the war theJapanese military also entertained contactswith British, French and American aviationfirms.

However, with the advent of hostilities andJapan having sided with the Axis powers, thecountry no longer had access to this broadspectrum of aviation companies and aircraftdesigns. Of course, through their acquisitionsof aircraft prior to the war and their subse-quent study of aircraft design, the Japanesewere capable of producing their own indige-nous aircraftwith a good measure of success.Prior to the war beginning, and continuingthrough until 1943, the Japanese obtained a

number of German aeroplanes. Some wouldsee series production such as the BiickerBii 131 Jungmann basic training aircraft,while others were obtained for evaluation oras comparison aircraft to be pitted againstJapanese planes.

Formal agreements between Japan and

Germany did exist during this time, but it wasthe signing of the Economic Agreement ofJanuary 1943 and, later, the ManufacturingRights Agreement of March 1944, whichpaved the way for increased German techni-cal exchange. These agreements, however,restricted Japan to only acquiring technologythat Germany's war machine was fielding

operationally. This clause denied Japanaccess to the advanced research being con-ducted by Germany's war industry. In addi-tion, there were some in the Germanindustrial sector and government who werereluctant to share the fruits of their labourswith Japan. Nevertheless, Japan was able toobtain a considerable amount of war mater-ial for her army and navy forces. A third agree-ment, the Patent Rights Agreement drafted inDecember 1944, was meant to protect tech-nological advancements and prevent confis-cation ofpatents. The Japanese dragged theirfeet on the agreement and it was neversigned.

It would take a decree by ReichschancellorAdolf Hitler in January 1945 to remove therestrictions of the 1943 and 1944 agreements,following which Japan had full access to theGerman military industry including experi-mental projects. However, by this time it wastoo little, too late, because both GermanyandJapan lacked the capability to ship material toJapan by sea or by air.

Perhaps surprising given the verylong list oftechnical exchanges that left Germany forJapan is that there was very little that went theother way. Germany was content to receivecurrency in exchange for the designs anddata - Germany needed raw materials for herwar industry. One of the very few examples ofJapanese technology that was acquired byGermany was a single Nakajima E8N floatplane (codenamed Daue by the Allies) that,oddly, ended up disguised in British markingsand was used by the German merchantraider Orion. The only other occasion whenGermany attempted to acquire a Japaneseaircraft, the Mitsubishi Ki-46 (codenamedDinah), the Japanese ensured that the nego-tiations with the Luftwaffe for a manufactur-ing licence went nowhere.

Japan would receive all manner of wargoods and data from Germany during the warand it would make for a long list were every-

thing to be included. As such, the list pre-sented here is limited to aircraft andselections pertinent to the experimentalnature of the subjects in this book.

142 hpaNEse SscRtr PRoJECTS: ExpERruEllral AIRcRnnr ol rHE IJA,cNl IJN 1939-1945

Pre-World War 2 GermanAircraft Exchange (l 914-38)Dornier Do C transportln 1927, Kawasaki imported seven aircraftfrom Dornier including the Do C Komet.Although rejected by the Japanese military,Kawasaki used the Komet to fill an order forthree passenger transports from the newspa-per service Asahi Shimbun Sha. The three air-craft, known as the Kawasaki-Dornier Komet,were built from imported components.Kawasaki later imported a Dornier Merkur, anupdated Komet, leasing the aircraft as theKawasaki-Dornier Merkur to Asahi Shimbun.However, this Merkur would instead see ser-vice with the fumy as the Aikoku No. 2 afterits conversion to an ambulance. Used duringthe Manchurian Incident, the Aikoku No. 2

was very active in casualty evacuation andupon retirement became a monument.When the Russians invaded Manchuria in1945, the plane was burned by the retreatingJapanese troops.

Dornier Do J Wal flying boatIn 1 929, Kawasaki received an order for a pas-senger flying boat. As they already had animported Dornier Wal flying boat from whichto source a design, Kawasaki essentially pro-duced their own version using imported com-ponents from Dornier. A total of three werebuilt by 1930, being flown as liners for regularpassenger services.

Dornier Do N heavy bomberln 1924, the Army asked Kawasaki to producea bomber to replace types already in selice.To this end, Kawasaki enlisted Dornier andBMW as coilaborators on what would becomethe Type 87 Heavy Bomber. Dornier designedthe Do N and the plane was buitt by Kawasaki,the first completed in 1927. After a year of testing, the bomber, now called the Tlpe 87, wasaccepted into army service, the last of the 28

bombers being delivered in 1932. Kawasakiproduced the BMW VI for the Type 87 underlicence. Equipping a handful of bomberchutai, the Type 87 would see brief actioning the Manchurian Incident of 1931.

Focke-Wulf Fw42 bomberThe Fw42 was a design for a canard-equipped twin-engine bomber. Various revi-sions of the design were made with windtunnel models undergoing testing from 1932

to 1933. Once the final revision was settled, afull scale mock-up was built. The Japanesewere invited to review the mock-up, Focke-Wulf hoping to entice sales of the bomber orlicence rights. The Japanese showed no inter-est and the Fw42 was soon cancelled.

Focke-Wulf Fw2005-lAnnounced with a major publicity stunt, theFw2005-1 'Brandenburg' took off for Japanfrom Berlin, Germany, on 28 November 1938

and arrived in TOkyd in a little under 48 hours.The Japanese were impressed by the Fw200and early in 1939 the Dai Nippon KabushikiKaisha (Japan-Manchuria Aviation Company)contracted Focke-Wulf for five Fw2008 Con-dors. Attached to this was an order for a sin-gle Fw200B for the IJN as a maritimereconnaissance aircraft. However, with theoutbreak of the war in Europe, none of theseorders were fulfilled. The Allies felt, with goodreason, that Japan would soon be using theFw200 and gave it the codename Trudy.

Hansa-Brandenburg fl oat planeFour were built between 1 925 and I 926 as theAichi Type 15-ko Mi-go. Based on the Germanplane, Aichi refined the design but failed towin the Navy's competition for a reconnais-sance seaplane and so work ceased.

Hansa-Brandenburg W 33 float planeAs part of reparations from World War 1 , Ger-many sent Japan a single W 33 float plane.Highly impressed with the W 33, the IJNrequested a copy which resulted in the TypeHansa. 310 were built and served with the IJNfrom 1926 to 1928 before being retired; manywere converted to passenger float planes forcivilian use.

Heinkel HD 23 carrier fighterIn 1926, Aichi contracted Heinkel to design a

carrier fighter for entry into a Navy competi-tion io replace the Mitsubishi Type 10 fighterthen in service. Called the HD 23 by Heinkel,it was known as the Aichi Type-H CarrierFighter in Japan. Two were built by 1927 andmuch emphasis was placed on the capabilityof the plane to ditch at sea, including jettison-able landing gear and the ability for theengine to stop the propeller in the horizontalposition. However, performance-wise, theAichi Type-H Carrier Fighter showed up

their service life was short due to the adventof catapult launched seaplanes. The fewAichi Naly Type 2 aircraft were then sold tothe civilian market. Later, in 1930, three Type2 aircraft were converted to transports forcivilian use.

Heinkel HD 25 transportBuilt as the AB-1, Aichi used the Heinkel HD

25 as the basis for their entry into a 'made inJapan' passenger/transport contest operatedby the Aviation Bureau of the Department ofCommunications. The AB-1 could be con-verted to a seaplane if required and proved itsworth going on to win the contest and seeingseveral years' service in private hands.

Heinkel HD 26 single-seat float planeA single example was built by Aichi (also as

the Aichi Nar,y Type 2) while the Navy alsoacquired a Heinkel constructed HD 26. Bothwere tested in 1926, but like the two-seater,the model was made obsolete by catapults.Both aircraft were turned over for civilian use.

Heinkel HD 28 three-seat float planeThe Navy purchased one HD 28 from Heinkelin 1926. Tested by the Naly, problems withthe Lorraine-Dietrich engine saw the HD 28failing to meet expectations and in 1928 theNaly withdrew their interest in the design.

Heinkel HD 56 seaplaneTo meet a 1929 Navy need for a catapultlaunched seaplane, Aichi once more turnedto Heinkel and imported the HD 56. Meetingthe needs of the Navy after modification, itwas accepted into selice in I 931 as the AichiE3A1 beginning with the first deliveries out ofan eventual total of 12 aircraft. The E3Al sawcombat during the Sino-Japanese conflict,operating from Jintsu-class cruisers. It didnot, however, remain in service long, beingreplaced with superior aircraft. Some E3A1

seaplanes were retained by the Naly as train-ers with the remainder released to the civilianmarket.

Heinkel HD 62 three-seat float planeAichi turned to Heinkel to produce a long-range reconnaissance float plane to meet a1931 request by the Nary for just such a craft.Called the Aichi AB-5, testing showed thedesign to be sound but with room for furtherrefinement. This would result in the 48-6 of1932 which, despite being successful, wasnot accepted into selice having been beaten

a Kawasaki design.

kel He 50/He 66I 933, the Navy issued requests for a carrier

dive bomber. Aichi elected to utilise Heinkel'sHe 50 which was then entering service withclandestine military air force training units.Called the He66 for export reasons, Heinkeldelivered a single He 66 to Aichi who, aftersome modifications, submitted it to the Nar,y.

Winning the Naly's competition, the modifiedHe 66 was then licence built in Japan, enteringselice with the Naly in 1935 as the AichiD1A1. The DlAl would see action in China in

lost th-E ceff56'Tition to Naka

Heinkel HD 25 two-seat float planeLicence-built in Japan as the Aichi Navy Type

this aircraft saw service on a number of

GERnreru TEcHrurcn,I- ExcHnncn wrrH JApAN - A BnrEp OveRvrEvl 143

1937. The Allies, thinking the DlAl would bemet in battle, assigned it the codename Susre.

As it was, the DlAl remained in Japanese ser-

vice only as a trainer, having long since beenwithdrawn from frontline seruice.

Heinkel He 70

light reconnaissance bomberIn the late 1930s, a He70 was imported toJapan. Few details are available but the wingform of the He 70 would later provide the

influence for the wing design of the AichiD3A1 carrier bomber, known to the Allies as

Val.

Heinkel He I l2B-0 fighterIn 1937, the IJN was seeking new fighters tocombat the increasingly modern aircraftbeing encountered in China. Heinkel was at

the time looking to export the Hel12, a

design which was ultimately rejected by theLuftwaffe. The IJN placed an order for 30 HE

112B-0 fighters, known in Japan as the ATHelType He Air Defence Fighter. I 2 of the 30 weredelivered though Japanese pilots disliked theperformance of the plane and mechanics had

difficulties maintaining the liquid-cooledengines. As Japanese fighters of improvedcapability were entering service, theHe 1 12B-0 never saw combat and the Japan-

ese cancelled the remaining l8 aircraft. Ser-

viceable He 112B-0 were used as

instructional aircraft and as means to studyGerman manufacturing techniques. Figuringthe He l12B-0 was in active selice, the Alliescodenamed the aircraft Jeny although it wasnever encountered.

Heinkel He I 18 dive bomberWith the Luftwaffe uninterested in theHe 1 18, Heinkel found the Japanese receptiveto ihe plane. The IJN placed an order for a sin-gle He 118 to be delivered by February 1937

along with the licence to manufacture theHe 1 l8 in Japan. The IJA also purchased a sin-gle He118 for delivery by October 1937.

Known in Japan as the DXHel, HitachiSeisakusho was to be the company thatwould produce the licensed aircraft. The

He 118 V4 was shipped to Japan and

bled at Yokosuka for the IJN, but during aflight it broke up in the air and the IJN

doned the plane. The IJA received the He I

V5 months later but it too lost interest and

Heinkel received no further orders.

Junkers G 38/K5l healybomberThe Army sought to have their own version ofthe Junkers massive G 38 airliner and inSeptember 1928, Mitsubishi entered into acontract with Junkers for the design specifi-

cations, blueprints, manufacturing data andlicence to build the aircraft as a bomber,known as the K 51, the export version of theG 38. Mitsubishi sent designers to Germany in1928 to study the G 38 and production tech-niques, and by 1930, the necessary tools, jigs

and material were imported and in place.

Junkers sent a team of engineers to Japan toassist with the production. The first bomber,the Ki-20, was completed in 1 93 1 . A total of sixwere built from 1931 to 1935. Kept in secret,the general public was not made aware of theKi-20 until 1940 when three Ki-20s partici-pated in a parade fly-over. The Ki-20 did notsee action.

Junkers K 37 bomberA single K 37 bomber was imported throughSweden and was donated to the Army as

Aikoku-l. Used during the Manchurian Inci-dent, the Army was impressed with the K 37

and in 1932 asked Mitsubishi to make a simi-lar bomber. Using the K 37 as a basis and cap-italising on experience from the Ki-20, theprototype Ki-1 heavybomberwas completedin March 1933. Despite problems with theengines, the Ki-1 was adopted to replace the

old Type 87. The Ki-l-ll soon appeared in anattempt to fix issues with the Ki-l but it wasnot liked by the crews that flew it. Another air-

craft, the Ki-2 light bomber, was also builtusing the K 37 as a basis. The Ki-2 and laterKi-2-ll (both being built from 1933 to 1938)

proved very successful, seeing action inChina and later as trainers into the late 1930s.

The Allies thought the Ki-2ll was still in ser-

vice when the war began and assigned it thecodename lourse.

Junkers Ju 90 transportOn 25 July 1938, Mitsubishi entered into nego-tiations with Junkers on behalf of the IJA towork with the German company to producea bomber version of the Ju90 transport. Tenwere to be completed and flown to Japan.The IJA even allocated the designation Ki-90

for the bomber. However, Junkers eventually

Junkers Ju 160 transportThe Ju160 was an improved Junke 60,

latter having lost to 70 in

the market. Lufthansa pur-chased 1 1 Ju 160A-0 and 10 Ju 160D-0 6-pas-

senger aircraft, putting them into service in1935-36. Two would end up in Manchuria,registered as civilian aircraft. The IJN pressed

them into service as the LXJ.

L.V.G. D.IXThe D.lX provided the inspiration for theSeishiki-l which used an imported MercedesDaimler 100hp engine, later licence-built inJapan. The Seishiki-1 was completed in 1916

but the biplane's poor performance resultedin further development being cancelled.

Rohrbach R flying boatThe Nalywas very interested in the metal air-craft construction techniques used by theGerman company Rohrbach. Mitsubishi wasasked to study the techniques and the twocompanies would form Mitsubishi-RohrbachGmbH in Berlin in June 1925. A total of threeRohrbach flying boats were to be imported,the R- I , R-2 and R-3, known collectively as theMitsubishi Experimental Type-R flying boats.Although these aircraft would prove to havepoor take-off and alighting that denied themmilitary service, they did provide invaluableexperience to Mitsubishi when it came tometal stressed skin construction.

Rumpler TaubeThe Imperial Flying Association purchasedtwo Rumpler Taube aircraft prior to the out-break of World War 1. As Japan was part ofthe Entente Powers, and thus against Ger-

many, the Japanese Army bought the twoTaubes from the Association for use in actionin the Tsingtao campaign. With no aircraft,the Imperial FlyingAssociation built their ownversion of the Taube calling it the Isobe KaizoRumpler Taube. The solitary aircraft first flewin 1915 before being wrecked in a crash laterin the year. The remains were cannibalisedand used in the Ozaki Soga-go of 1917.

144 JapnNrse SEcRsr PRo;lcrs: ExptRrugNral ArRcnenl op rHe IJA AND IJN 1939-1945

World War 2 German Aircraft

Arado Ar 196 float planeIt was reported byAllied int e selvlces

the Japanese tu196 float

gest this occurred. The Germans operated asubmarine facility at Penang, Malaysia, andthe unit used the Ar 196 in Japanese colourswhich may have led to the confusion in theintelligence report.

Arado Ar234 Blitzjet reconnaissance bomberThe Ar234 was a twin-turbojet, single-seatreconnaissance bomber that entered sewicewith the Luftwaffe in September 1944. Alliedintelligence intercepted a communicationbetween Germany and Japan in March 1944that confirmed that the Japanese had data onthe Ar234. It was assumed that the datarelated to the Ar234A, which was not asadvanced as the subsequentAr2348 models.Another report went so far as to say produc-tion plans were in place to build the latestAr 234 aircraft but this was based solely on thefact another report stated that the FuG 136Nachtfee visual command indicator equip-ment (used in the Ar234P series night fight-ers) had been delivered to Japan in January1945. It would become clear that the Ar234was never produced in Japan and it isunknown exactly what data Japan didreceive on this aircraft.

Bachem Ba349 Natter rocket interceptorThe Natter (meaning 'Viper' in German) wasa rocket powered point defence interceptor -in essence, a manned rocket launched verti-cally towards enemy bombers where itwould use its high speed to avoid enemyfighters and launch a salvo of either 73mmHs217 Fohn or 55mm R4M rockets at theattacking bombers. The pilot would theneject from the 8a349 and return to earth viaparachute along with the engine portion ofthe aircraft. The Ba 349 required little in termsof critical war materials and could be con-structed by semi-skilled workers. Severalunmanned test flights were flown but the onlyrecorded manned flight ended in the death ofthe pilot. Despite a handful being deployed,none saw action. Allied intelligence surmisedthat the Japanese were provided with infor-mation on the Ba349 and they were correct.The RLM ordered Erich Bachem to give theJapanese a complete set of plans for theBa349. However, the submarine carrying thedata was lost at sea. When this transferoccurred is unknown but it would likely havebeen late in the war.

z

o

oza

Genu,qru TecHNrcaL ExcHervcp wrrH Japnru - A BnrEr OveRvrsw t45

Blohm und Voss Hal42 heavy bomberThe Ha142 (later the 8V142) was the landversion of the Ha139 float plane. Unlike thesuccessful Ha 139, the Ha 142 was, ultimately,a failure when converted from a transport toa reconnaissance bomber aircraft in 1940.

Despite this, the Blohm und Voss P.48 projectwas listed as a bomber version of the Ha 142

for Japan. Most likely, this remained a paperconcept with no further action being taken as

only four BV 142 aircraft were built before thetlpe was withdrarnn from service in 1942.

Biicker Bii 13l Jungmann trainerIn August 1942, the Japanese obtained thelicence to produce the Jungmann trainer(meaning 'Young Man' in German). TheBti 131 had been demonstrated to the Japan-ese in 1938 and a total of 22 aircraft were pur-chased from 1938 to 1939. The Japaneseattempted to make their own version of theBii 131 but the results paled in comparison tothe German aircraft and this resulted in the1942 acquisition of production rights. TheBl I 31 was produced for the IJA as the Koku-sai Ki-86a and for the IJN as the Kyushu KgWlMomiji (meaning 'Maple'). One all-woodKi-86b was completed in February 1945 butremained a prototype. All told, 339 K9W1 and1,037 Ki-86a aircraft were built from 1942

through 1945. The Allies codenamed both air-craft Cypress.

Dornier Do2l7 heavy bomberIt was reported the Japan received twoDo217 aircraft in January 1943, and that byJuly 1943 the Japanese had purchased themanufacturing licence for the bomber. How-ever, no record exists of any Do 2 1 7 being sentto Japan, nor the purchase of the licence, andso the report may have been made in error. T

to them.

Dornier Do 635long-range reconnaissance aircraftThe Do 635 was basically two Do 335 aircraftmated together by way of a centre wing sec-

tion. Conceived in mid-1944, the design of the

Do 635 was completed soon afterwards and

\Dornier Do335 Pfeil fighter bomber Heinkel Hel77A-7 bomber \The Pfeil ('turow') was a twin engine, pull&q The IJN were interested in the He 172 andpusher fighter and one of the fastest piston)'.-negotiated to produce the bomber,jn-Iapan,engine fighters of World War 2. Although a r,rn\tbHitacttl !-u!4igg it under lieente in Chiba

number of Do 335s of various makes would in1942. The major change was that the Japan-

eventually be built (and ten Do 335A-0 aircraft ese version would use four separate engines

were used in the field by Erprobungs- to avoid the plethora of problems the Ger-

kommando 335), the type did not enter ser- mans encountered with the original coupledvice with the Luftwaffe. Nevertheless, it was engine design. Sample tools were delivered to

believed that the Japanese were provided Japan by submarine but Heinkel was unablewith a description of the Do 335 in March 1945 to ship the remainder of the machining appa-

but no substantive information was released ratus and jigs and production was dropped.

the RLM ordered four prototypes and six pre-production aircraft. By the close of 1944, theDo635 was shared with the Japanese whofound the design intriguing but outside oftheir interest. The Japanese made no furthermoves to obtain the aircraft. Although windtunnel models were completed and testedand a mock-up of the cockpits were built, theDo 635 was cancelled on 5 February 1945.

Heinkel He l00D-0 fighterIn 1940, Japan paid 2.8 million Reichsmarksfor three He 100D-0 aircraft and the manufac-turing rights. It was planned to produce theHe100D-0 as the AXHeI but the war pre-

vented Heinkel from delivering the requiredjigs and tools and so production was aban-doned. Nevertheless, the Japanese were veryimpressed with the fighter and the designwas a major influence for the successfulKawasaki Ki-61 Hien. Interestingly, Alliedintelligence thought that details of a 'He 1 l3'were received by Japan in July 1943. The'Hel13'was actually the He100. A propa-ganda ruse using the few He 100s built tried tomake it appear that the type was in Germanservice and this succeeded in fooling Alliedintelligence who used the 'He 113' designa-tion in their reports.

Heinkel He I 19

The Japanese purchased the He I 19 V7 andV8 in 1940. See the chapter on the KrlgishdR2Y Keiun for more information.

Heinkel He 162 jet fighterSee the Tachikawa Ki-I62 chapter for moreinformation concerning the Japanese acqui-sition of this fishter in-A;ril oi i9+S-u\,\

One He 177A-7 was to be flown to Japan in .

1944 lo serve as a manufacturing pattern air-frame and evaluation aircraft but the bomb'erlacked the range, even after modification, iomake the flight via the route demanded by the 'Japanese running through Persia and India.

Some sources list the proposed plane as the

Hitachi 'He-Type' heavy bomber.

Heinkel He 219 Uhu night fighterThe Uhu, meaning 'owl'in German, was per-haps the most advanced night fighter to see

operational service in World War 2. TheJapanese are believed to have been aware ofthe He219 with full access to the relevantdesign data by July 1944. If this was the case,it is notknownwhat, if anything, the Japanesedid with the information.

Heinkel He277 heavy bomberThe He277 was, essentially, the He 177 withfour separate engines instead of the coupledengines which caused so many problems forHeinkel and maintenance crews. Unlike theHe177, lhe He277 would never enter pro-duction, being cancelled in July 1944 infavour of more fighters. It was believed thatfull details of IheHe277 were provided to theJapanese in March 1944. One could assumethat since the proposed Japanese version ofthe He 177 would use four separate engines,information on the He 277 would have beenofvalue.

Henschel Hs 129twin-engine ground attack aircraftThe Hs 129 was a dedicated ground attackplatform which, while having problematicengines and poor manoeuvrability, pos-

sessed excellent armour and the ability tocarry a wide array of armaments. Allied intel-ligence reported that German sources listedtwo Hs 129 aircraft for delivery to Japan some-time in 1944. Since none reached Japan, itcan be presumed that they were never dis-patched and the aircraft were used in Ger-man service.

Henschel Hs 130high-altitude medium bomberThe Hs 130 was the evolution of the Hs 128,

the latter a testbed for pressure cabins andhigh-altitude flight. Initially developed as areconnaissance platform, the Hs 130 wouldlater evolve into a bomber. Several prototypeswere constructed and tested but the type didnot enter service and was cancelled in 1944.

It was believed by Allied intelligence that the

Japanese obtained complete details on theHs130 program in July 1944. Recently pub-lished photographs showing wartime Japan-ese notes on the Hs 130, including sketches ofthe p,4essure c-abln and

-qs s o clA!"ed sys te m s,

-ednn ^ the i n te I I i gtncett

Fieseler Fi l03R Reichenberg \A US intelligence report stated that the Japan-

:€s€ w€r€ aware of the piloted versionqpf the

Fi I0$(vJ) ftying bornb and-wish66- to use

them. Codenamed'Reichenberg' by the Ger-

mans, 175 Fi 103Rs were built but the unit

146 JapnNssE SEcnnr Pno:Ecrs: ExpERIIl,tsr,JteL Alncnlpr oF THE IJA ano IJN 1939-1945

tasked with flying them, 5./KG 200 'LeonidasStaffel', would not see combat. The Fi 103R I,

II and lll were training versions - the Reichen-berg I was a single-seater without the fuguspulsejet engine, the Reichenberg II a two-seaterwith no engine and the Reichenberg IIIa single seat version but with the engine fit-ted. In all cases, ballast simulated the war-head weight. The Reichenberg IV was theoperational model. It has been suggested thatthe Reichenberg was the inspiration for theKawanishi Baika.

Fieseler Fi 156 Storcharmy cooperation/observation planeIn June 1941, Japan received one example ofthe Fi 156 for evaluation. The IJA wasimpressed with the 'Stork' and desired tohave its or,r'n version. The result was theKokusai Ki-76, codenamed Sre//a by theAllies. The Ki-76, despite the obvious similar-ity to the Fi 156, was not a direct copy as theprototlpe was completed and flying beforethe Japanese received their Fi 156. In com-parison testing, the Ki-76 was actually foundto be superior in all areas except landingdistance.

Focke-Achgelis Fa 330 Bachstelze rotorkiteThis little engine-less rotorkite (the Germanname means 'wagtail') was used by a smallnumber of German U-boats as a means toprovide increased visibility to observers whilethe submarines were on the surface. TheFa 330, after being unpacked and assembled,was tethered to the submarine and the windrvould turn the three-bladed rotor as the sub-marine moved forward. Once airborne, theobserver could see up to 25 miles instead ofthe few miles afforded to an observer in theconning tower. One intelligence report sug-gested that the Japanese may have shown aninterest in the Fa330 had they been madeaware of it.

Focke-Wulf Fwl 90A-5 fighterIn 1943, the Japanese imported one exampleof this aircraft to pit against Japanese fighterdesigns and compare their performance.Figuring that Japan would use the Fw 190 incombat, the Allies assigned the codenameFred lo the aircraft but none encountered.

-/- ,-a- _\

-,,,/ \Focke-Wulf Ta 152 high-altitude fighter iIn April 1945, the Japanese purchased the j

specifications for the Tal52 as a means te/-rapraV acquire a high-altitude ng!!g1,-How-

ever, by thirtime, there was simply no wayfor the Japanese to act on the materialobtained.

Focke-Wulf Fw l90A-5 fighter. Ted S. Nomura/Mid Visions and Antarctic Press

Gotha Go 242 transport glider/Go244 transportIn a letter dated 7 February 1944 discovered atBad Eilsen in May 1945, the Deutsche MitsuiBussan requested from the Germans designplans for both the Go242 and the Go244, lhelatter being a twin-engine version of theglider. No evidence has surfaced to suggestthat either of these craft were sent to Japan.However, it is suggested that they were theinspiration for the Kokusai Ku-7 Manazuru(meaning 'Crane') glider and the poweredversion of the Ku-7, the Kokusai Ki-105 Otori('Phoenix'). Both the Ku-7 and the Ki-105were codenam ed Buz z ard by the Allies.

Junkers Ju 52l3m transportThough the Japanese had no interest in the'Tante Ju', the Allies thought the Japanesewould be using the transport in action. Thisidea may have stemmed from a May 1939

flight made by a Ju 52l3m to Japan to bolstertrade relations. As such, the plane was code-named Inxle.

Junkers Ju 87A'Stuka' dive bomberIn 1940, a single Ju 87A was sent to Japan forevaluation. By 1939, all A models had beenwithdrawn from frontline German service,and after flight testing and study the planewas put into the collection of the Tokorozawamuseum. However, it was lost when themuseum was bombed. The Allies, believingthe Japanese would be using the Ju87,assigned it the codename lrene.

Junkers Ju88A-4 bomber

been verified and only the single Ju884,-4 isknown to have been delivered.

Junkers Ju 290 long range heavy bomberThe Ju 290 was initially a healy, four enginetransport aircraft that was reworked into along range maritime reconnaissance andbomber aircraft. It was felt that by October1943, the Japanese were in possession of thecomplete details of the Ju 290. Even if this wasthe case, it would appear the Japanese didnot act on the information and they may havebeen more interested in the Ju390. There isno evidence to suggest that the Ju 2904-7 wasever adapted as a 'nuclear' bomber for theJapanese, especially in light of the fact fewA-7 models were ever completed. Somesources suggest that Ju 290 flights were madeinto Manchuria carrying documents andother intelligence, possibly in exchange forraw materials from Japan, but informationhas never surfaced confirming these flightsand popular opinion in the face of current evi-dence is that they did not occur.

Junkers Ju 390A-l reconnaissance bomberln 1944, the IJA was very interested in thepotential of the Ju 390 as a strategic bomberand sought to obtain the rights to the aircraft.In the fall of 1944, the Japanese acquired themanufacturing licence and design plans forthe Ju3904'-1 long-range bomber reconnais-sance aircraft. By 28 February 1945, Major-General Otani of the IJAwas to have collectedthe plans and licence from the Germans butit is unknown if this ever occurred. In anycase, the Ju 390 V3, which was to be the pro-

The Japanese acquired a single example of totlpe - for the bomber reconnaissancetheJu88A-4in1940forthepurposesoftesI,.v.d65ign,WaSing and evaluating the aircraft as well as forthe study ofthe design. The Japanese had $g Junkers Ju488 Iong range bomber '\intentions of producing the bomber but ne\ The Ju488 was a design byJunkers to rapidly ,'.ertheless the Allies thought it likely they ..prgduce a long range bomber using compj---:-r-would and thus gave the Ju88 the codename nEiihf-aircratlttql in p{q4ucfion.4ofiUfn--Janice. As an aside, one intelligence report ing parts from the Ju 388K, Ju 188E, Ju 88A-15states that the Mitsubishi office in Berlin had and Ju 288C bombers, construction of twoa number of 'Ju 88K-5' (the export version of Ju 488 prototypes was begun (V401 andthe Ju88A-4) aircraft and parts shipped to V402), but prior to completion these wereJapan, perhaps in 1943, though this has never destroyed by French resistance forces in July

GEnunru TEcHnrcel ExcHANGE wrrH JApAN - A Bnren OvERvrEw t47

1944.\n November 1944, the Ju488 programwas cancelled. In January 1945, the Ju488

design was offered to Japan but neither the

IJA nor IJN took any interest in it. This rejec-tion sealed the fate of the project.

Messerschmitt Bf l09E-7 fighterIn 1941, the Japanese obtained threeBf 109E-7 fighters. These were pitted againstvarious Japanese fighter designs for compar-ison purposes. Despite the Japanese having

no intention of licence building the fighter,

lhe Allies anrlicipated thal the_y would. !.e_.- encountered in combata-nd gave the plane

lhe codename Mlfte.

Messerschmitt Bf I l0 heavy fighter

Bf I l0 the codename Doc.

Messerschmitt Me 1638 Kometrocket fighterFor detai see the chapter on the Mit-

Messerschmitt Me 209 fighterhigh-

for evaluation. After testing, no further inter-est was shown in the design.

Messerschmitt Me 262.4 Schwalbejet fighterFor more details, please see the chapter on theNakaiima Kitsuka and Nakajima Ki-201 Karyr.

Messerschmitt Me 309 fighterThe Me 309 was a failed attempt to create areplacement for the Bf 109. The tricycle land-

ing gear was cause for grief and in compari-son testing the Me 309 Vl came up short

'--against the Bf 109. Fully loaded, the Me309

offered only a marginal increase in speed overthe Bf I,09 and the latter could out turn the for-

mer. With the advent of the Focke-Wulf

Despite the failure of the Me 309, the Japanese

attempted to purchase the Me309 in 1943

prior to the termination of the program. Itwould appear that with the cancellation of theMe 309, no sales of the remaining aircraft ormanufacturing rights were offered to Japan.

Messerschmitt Me 323 Gigant transportAllied intelligence believed that the Japanesereceived plans and components for theMe323 Gigant (meaning 'Giant'), the pow-ered version of the massive Me321 Giganttransport glider. Although the Japanese wereinterested in large transports, there is no evi-

dence to suggest they had an interest in the

Me 323.

Messerschmitt Me4l0 healy fighterIt was thought by Allied intelligence that the

Germans had shared information on the

Me 410 with the Japanese in November 1942,

with other sources suggesting this occurredcloser to the end of 1943. However, no such

interest in the Me410 was shown nor wereany aircraft delivered. It may be that some

confusion was caused by the one Me 2l0A-2

that Japan did receive and was configured tothe Me410 standard.

Messerschmitt Me 509 fighterThe Me 509 rvas a planned derivative of theMe309, sharing components such as the tri-cycle landing gear. The Daimler-BenzDB6058 12-cylinder engine was housedinside the fuselage, behind the cockpit. Thepropeller was driven via an extension shaftwith the cockpit situated well forwards in thenose. The wings were mounted low on thefuselage. The Klgisho R2Y1 Keiun bears an

uncanny resemblance to the Me 509 and ithas been suggested that when the Japanese

sought the Me 309, information on the Me 509

was also provided to them. No evidence has

yet proven this, however.

50mm Bordkanone 5 (BK-5) aircraft cannonThis cannon, used operationally by the Ger-mans in the Me410A-1/U4 and Me410A-21U4heavy fighters for anti-bomber missions, gar-

nered interest from the Japanese who sawthe weapon at a Luftwaffe airfield in Posen inthe Warthegau. There is no evidence that an

example was sent to Japan.

A4 ballistic missileBetter known as the V-2, the A.4 was the firstballistic missile to be used operationally incombat. In an OSS (Office of Strategic Ser-

vices) report from September 1944, it wassaid that the Japanese had purchased thedesign plans for the 44. Another OSS reportadded that in February I 945 a Doctor Yamadaof the Chemical Research Institute broughtthe plans to Japan. It was surmised that the

Japanese were building the missile in Muk-

den (Shenyang) in Northern China for use

against targets in the Philippines and the Chi-

nese interior. However, the OSS reports

remained unverified and it was believed byother intelligence agencies that the Japanesewould not have had much interest in the A4,

let alone that they could construct it. Othersources say the Germans had no intentionof releasing information on the .A4 to the

Japanese.

Blohm und Voss BV 246 Hagelkornglider bombThe BV246 Hagelkorn (meaning'hailstone' inGerman) was a radio-guided glider bomb.1 ,100 examples of the BV 246 were built fromDecember 1943 through February 1944

before the factory producing them wasdestroved by bombing. Using a radioreceiver, the bomb also used a smoke gener-

ator to assist the operator in guiding the bombonto the target. Despite good results, it wasfelt the guidance system could be too easily

Originally, the Me 209 was designedspeed aircraft capable of breakingair speed record. In fact, the Me 209 !

Messerschmitt Bf l09E-7 fighter. Ted S. Nomura,/Mid Visions and Antarctic Press

Although the Japanese never imported the Fw.L90D and the superior performance itBf 110, Allied sources assumed that the air-.----6ffered, the Me309 was shelved with the

iiltwoun ne segn in combatand gave ihe remaining prototl,pes serving as testbeds.

worldwould

record at a speed 14km/h(469.22m Beginning withthe Me 209 V4, the design shifted to that of afighter. Despite a number of prototypes, the

Me209 was not accepted for service. Still,

Allied intelligence was positive that the Japan-

ese knew of the Me 209 and, in fact, a Japan-ese military attach6 in Berlin did recommendin 1943 that the manufacturing rights for the

aircraft be acquired as well as a sample air-

craft. It would appear this was not acted upon.

Messerschmitt Me 2l0A-2 heavy fighterOne Me 210A-2, Werk-Nr. 2350, was modifiedto the standard of the Me 410 (with the excep-tion that it retained the original Daimler-BenzDB601F engines) and sent to Japan in 1942

Other Exchange Items

t48 JnpnnpsE Secner Pno.rEcts: Expenll4sNlrll AIRcRnrr op rHn IJA arrrl IJN 1939-1945

jammed and production was not resumed.Allied intelligence believed that informationon the BV246 was made available to theJapanese prior to April 1944.

Donau-60 BolometerThe Danube-60 was an infra-red detectionsystem used to control coastal guns. It usedfour thermal sensors in parabolic disharrangements with a bolometer at each focalpoint. These dishes would detect the heatgiven off by ships, for example, through theirfunnels, and the data was then transmitted togun layers who would bring the guns to bearon the target. Zeiss produced the system atthe rate of 20-30 a month but how widespreadit was in service is unknown. That the Japan-ese may have been interested in this bolome-ter can be seen in their developments of theKe-Go (see the chapter on Japanese bombsfor more information).

Fieseler Fi 103 guided bombBetter known as the V-l or 'buzz bomb'(among many nicknames, German andAllied alike), the Fil03 was a crude cruisemissile first used in action against England.Intelligence reports claim that documenta-tion on the Fi 103 was provided to the Japan-ese in October 1943, and in November 1944,

the Japanese acquired a Fi103A. These

Japanese on the methods for airniques as practiced by III/KG 3

tech-53,

rvho fired the Fi 103 from Heinkel He 1

bombers.

Heinkel HeS 0ll turbojetThe HeS was to be the next generation of tur-bojet and was to be the powerplant of choicefor a great number of German projectdesigns, and also the first of the second gen-eration jet fighters such as the MesserschmittP 1101 and the Focke-Wulf Ta183 'Hucke-bein'. Only 19 were built before the close ofthe war and the engine never attained pro-duction status. Allied intelligence cited a l2March 1945 letter from Kurt Lammertz toDirectorWolff of Heinkel-Hirth stating that theIJN should be supplied with complete plansfor the HeS 011 engine and that it should betransferred via submarine. There is no evi-dence to show this transfer was completed.

Henschel Hs293 guided bombThe Hs 293 was an SC500 bomb onto whichwings, a tail and a rocket engine were mated.The Hs293A-1, which was the only opera-tional model, used radio signals to direct itsbomb to the target. Later test versions used

Messerschmitt Me 210 twin-engined fighter. Ted S. Nomura/Mid Msions and Antarctic Press

reports also suggest that the Japanese of a radio guided munifar more interested in air launchingthan ramps, and data was to the Henschel Hs294 guided bomb

wire-guidance as ameans to defeat jamming.The weapon entered service in 1943 and,early in that year, a Japanese delegation wasgiven a demonstration of the Hs2934-l at afield in Gartz in Germany. The Germans keptinformation on the improved, wire-guidedHs 2934-2 from the delegation. It is unknownif the Japanese acquired further informationon the weapon and Allied intelligence reportssuggest that, if they had, the Hs 293 would nothave reached service until the fall of 1945. Inaddition, one report makes the assumptionthat the Hs 293 was an influence on theKrlgisho MXYT Oka in so far as a human oper-

heavier engrnes.The Hs294A used radio guidance, theHs 2948 wire guidance and the Hs 294D usedtelevision guidance. The Hs294 failed to see

selice. However, in December 1944, IJN rep-resentatives met with German Air Ministryofficials to discuss the Hs 294 but with whatresults is unknown.

Rheinmetall-Borsig MK 108

30mm aircraft cannonKnown as the 'pneumatic hammer', the MK108 cannon was a very successful weaponencompassing heavy hitting power, ease ofmanufacturing and compactness in onepackage. Despite having a low muzzle veloc-ity which reduced range, it was used on anumber of operational German aircraft andsecret projects. The Japanese were veryinterested in manufacturing the cannon andstudied the requirements to produce it. Cap-

tured documentation in June 1943 suggestedproduction was soon to be underway as theJapanese had received examples of the MK1084-2 cannon. The MK 108 was not built inJapan.

Ruhrstahl-Kramer PC 1400X Fritz-Xguided bombThe Fritz-X was a guided munition made fromthe unguided PC 1400'Fritz'bomb. Using acruciform tail arrangement with guidablefins, the Fritz-X was directed to the target viaradio signals sent by the operator in thelaunch aircraft. To help visibility, flares wereinstalled in the tail. The munition saw selicefromAugust 1943 to the end of the warinApril1945, being relatively successful in the anti-shipping role. The Japanese were aware ofthe Fritz-X and information on the bomb wasavailable to Japan in September 1944. It isunknown if any examples were provided or ifthe Japanese pursued the weapon further.

Kramer X4 air-to-air guided

idered to be the first air-to-air missile tobe used successfully in World War 2, the X4was a short range, wire-guided, rocket-pow-ered AAM that was extensively tested afterbeing conceived at the start of 1943. The X4was test launched from a number of aircraftsuch as the Junkers Ju l88L and Focke-WulfFw190F-8 and was envisioned that theMesserschmitt Me 262 would carry the X4 intooperational service. Despite 1,300 being built- and suggestions that some were test fired inaction against American bombers - no X4saw active service. Allied intelligence ser-

vices assumed that the Japanese were awareof the X4 development but no evidence has

surfaced to confirm this.

This was an improved version of the He 293,incorporating a longer, more pointed nosq

GERuaru TEcur'rrcal ExcHaNcE wrru hpax - A BRrsn Ovnnvtew t49

Bibliography

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Donald, David. The Complete Encyclopedia ofWorld Imperial Nauy Land Attachers. Tokyd, Gakken, 2003. Speed Machines: General PIan No,2. April 1939.

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2004 Samoloty Wojskowe Swiata 1935-1945

1 5 Jan 2009. w"vwv,samoloty.ow.pVstr0 I 6.htm

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Online forums:

w"*w.j-aircraft.com

wr,wv.secretpro j ects. co.uk/forum/index. php

Peter Allen

A UK-based graphic designer, Peter rvorks in many

areas including advertising, graphics for business,

ivatercolour painting and illustrating vehicles, bothcivilian and military. He has a fondness for secret air-

craft projects, from British to Japanese, and many

more in between. E-mail: aliensnest@yahoo.com

Website : http ://wr,lw.fl itzerart.com(http//wwl,v.fl itzerart.co.uk coming soon)

Muneo Hosaka

Muneo Hosaka received a degree in art and upongraduation entered the business sector as a computergraphics artist. In 1996, he turned fieelance. Muneo's

3D aviation artwork has seen print in many Japanese

publications over the years, spanning operational air-

Artist Biographies

craft and X-planes. His drii'e comes from his desire to

see project aircraft take to the sky, if only as artwork.

Muneo was born on 29 September 1961 and currently

resides in Japan, his home country.

Website : http //ivww. ne. jp/asahilgreen/wave/

Gino Marcomini

Born on 16 June 1981 in Pirassununga, Brazil, Ginograduated from the industrial design course at Uni-

versidade Estadual Paulista in 2005. He has worked inproduct and graphic design, being master designer

on Coorperdata's Industrial Pole and is a partner ofthe Brazil based design agency Abissal Design. In

addition to design work, Gino teaches technical

courses in industrial design, mechanics and mecha-

tronics using Solidworks CAD softr,vare and 3D[ilar as

the poly modelling software. He is currently working

on his post-graduation studies at the Universidade

Federal do Paranii to be concluded in 2009.

Website: http://wmw.oxygino.com

Ted Nomura

Since 1986, Ted has lvritten and drawn over 100

comics. He is best known for the alternative history

comic series 'Families of Altered Wars' which in

recent yeals created a number of comic spin-offs,

nolably Luftwaffe: 1946, World Wor 2: 1946 and

Kamikaze: /946. In addition, he has produced a num-

ber of comic formatted technical manuals on Luftwaffe secret projects, co-authored with Justo Miranda.

Ted's work is most often published through the San

Antonio, Texas, comic publisher Antarctic Press.

JepaNrss SrcRsr PRoLscrs: ExpsRrN,rENraL Atncnarl on rHE IJA AND IJN I 939-l 945 1Sl

Ronnie OlsthoornWith over ten years of professional experience and a background inaeronautical engineering, Ronnie's aviation art boasts high levels of realismand accuracy. Every custom artwork is preceded by great amounts of researchto ensure the client gets as authentic an image as possible. Yet Ronniedoesn't lose sight of the artistic side of things and each image is

a striking visualisation of the real thing.

Ronnie's artwork has featured in and on books, magazines,model kit box tops, computer games and aviation museums.But the most rewarding work he has done were commissionsto honour veteran pilots and their families. The positive andoften emotive feedback from veteran pilots is the greatestreward any aviation artist could ask for.

To commission custom artwork, contact Ronnie on

ronnie@skyraiderSd.comor alternatively via his website at

www.slqraider3d.com

Prints of his aviation art are available through

www. di gitalaviationart. com

152 Japa\sse SEcner PRo;Ecls: ErpERruENlal ArRcRarr or rHE IJA aNn IJN 1939-1945

Japlxese SscREr Pno:rcls: ExpERtnrENrar- ArRcnapr or rHs IJA arn IJN 1939-1945 153

.'Y

C

:t

'* -..$t*,1,.*o'

o,l,rffi/-D

We develop aviation art in 3 view and

in action mode for scale kit boxes,

magazines, books, covers, framework, ...

www.duh raviationart.comcontato @eletronicmedia.com.br

o

r'LVl AL I 6l^,lra-rF

154 J,lpl.-csc Secnnr Pno.lEcts: ErpEnrttrxLeL ArtrcRlrl oriHn IJA,qxo IJN 1939-1945

HypotheticalAircraft Profiles

ln 1986, Ted Nomura self-published his comic Tigers of Tena:Families of AlteredWars under his Mind Visions label. In 2006, his

work celebrated 20 years of alternative military history in visual

form. Antarctic Press assumed the printing duties for Nomura'scomics, not only continuing Tigers of Tera buI with spin-offsincluding the popularluftuoffe: 1946, Kamikaze: 1946, and manyothers, to include several x-plane technical manuals. The latterpublications were done with the assistance of Justo Miranda.Nomura's profile artwork in this book come from his many comicsand where available, the alternate history he has given them isprovided.

Tachikawa Ki-229 as operated by the IJA. This was the Japanese version ofthe Horten Ho 229, Horten MI trainers were used by the IJA as the Ki-226.Ted S. Nomrrra-/Mind Visions and Antarctic Press

JnpnNEss SEcRET PRorrcrs: Expsnruenral ArRcRnrr on rris IJA nNr IJN 1939-1945 155

Nakajima Kitsuka (code namedlrnda)' flown byan unidentified Tokkotai unit. Ted S. Nomura/Mind Visions and Antarctic Press

Tachikawa built Ki-201 Karyu (code named lee)prototype, flown by the Fussa/Tachikawa IJA TestSquadron, September 1945. Ted S. Nomura,/

Mind Visions and Antarctic Press

Kawasaki built Ki-20I Karyu (code named lee)flown by a unidentified Japanese home defenseunit, March 1946. Ted S. Nomura,/Mind Visions and

Antarctic Press

Kawasaki Ki-88 (code namedBonnie) as brieflyoperated by the U.A. Ted S. Nomura/Mind Visions

and Antarctic Press

Tachikawa Ki-94J.Ted S. Nomura/Mind Visionsand Antarctic Press

156 JaparuEss SlcRsr PRo:tcrs: ExpsRtN,tENtaL AIncRapr oF THE IJA AND IJN 1939-1945

Tachikawa Ki-162 (code named Jan), flown by theFussa/Iachikawa IJA Test Squadron, November 14,

1945. Ted S. Nomura'/Mind Visions and AntarcticPress

Messerschmitt M e262L-2 (code named Marsfta)flown by the 58th Tokkitai, December I, 1945.Ted S. Nomura,iMind Visions and Antarctic Press

Heinkel Hel I I(code named Bess)with FieselerFi l03R-IV (codenamed Crndy) asoperated by the47th Tokkdai,December 7, 1945.Ted S. Nomura/Mind Visions andAntarctic Press

Nakajima Ki-87 (code named Jeffl) as flown byMajor Sabur0 Kurusu, Fussaflachikawa IJA TestSquadron, November 14, 1945. Ted S. Nomura,/Mind Visions and Antarctic Press

Rikugun Ki-93 (code named Dora)flown by Hauptmann Dora Oberlichlof J/KG 200, operating at the Fuesa/Tachikawa IJA Test Center,November 14,1945. Ted S. Nomura/Mind Visions and Antarctic Press

Tachikawa Ki-94-II (code named Ted) flown byLieutenant Colonel lchiro Mikasa, Fussa,/TachikawaIJA Test Squadron, November 14, 1945. Ted S.

Nomura,/Mind Visions and Antarctic Press

JnpnNesp SEcRrr PRo;rcts: ExpEnruENreL ArRcnarr oF rHE IJA AND IJN 1939-1945 157

INDEX OF PERSONALITIES

(rank, professional qualifications and political status are ignored.)

Akita, Yoshio 105

Andd 109

Aoki, Kunihiro 28,31

Aramaki 77

Campini,Secondo ll4, 115

Doi, Takeo 9, 15

Fujikura, Saburo 105

Fujita 135

Fujita, Nobuo 139

Fukuba 134

Genda, Minuro 7l

Guillaume, Ivla,{ime 114

Hanalima, Koichi l14

Hattori, Rokuro 7lHasegawa, Tatsuo 56

Hayashi 24,59,60

Hayashi, T. 133

Heinkel, Emst ll4Hikita, Tetsuo 97

Hino, Kumazo l7Hizuta 135

Honjo, Kiro 91,92Inuzuka,Toyohiko 77,99

Itakawa 135

116 120

Iwaki, Kunihiro 72

Iwaya, Eiichi 62, 97, I 15, I 16

Jyo, Eiichiro 70

Kaiya, Tsutomo 72, 73

Kasai 98

Katahira 62

Kalashiro 62

Kato 27

Kayaba,Shiro 17,18

Kihara 62

Kimura, H, 50

Kimura,Hidemasa 17,71, 77

Kitaiima 79

Kitano, Jun l5Konishi 135

Koshino 101

Kozono, Yasuna I 12

Kubo,Tomio 27

Kumamoto 97

Kusaba, Sueyoshi 139

Langley, Samuel Pierpont 135

Lorin, Ren6 l7Matsui 97

Matsumura, Ken'ichi ll5, 116

Matsurua, Yokei 7l

Merkulov, I.A. l7Miki,Tadanao 71

Mitchell, Archie 140

Mitsugi, Tadanao 7lMiyaishi, Yoshitaka 85

Miyata, Masanori ll5Mizuno 27

Mizuyama,Yoshiyrka 20,21

Nait6, Shigeki 18

Nagamori, K. 133

Nagamori, Yoshio 60

Naganishi 62

Nagano,Kazutoshi 72,74

Nagano,Osamu ll5, l17

Nakajima, Chikuhei 108

Nakamura, Katsuji ll2Narabayashi,Tashiichi 105

Noda 24

Index

Nonaka, Goro 72

Numachi,Fukusaburo ll4Obayashi, Soemu 70

Ogawa 62

Ogawa,Taichiro 17,61, 71

Ohain, Hans von I l4Okamura, Motoharu 72

Onishi, Takajho 70

One 77,97

Ono, Kazuo ll5, l16ota, Mitsuo 70

otsuki, Shiro 79

Ozawa, Jisaburo 70

Payen, Nicholas Roland l0l, 103

Poyer, H.M. 12

Saba, Jiro 7lSakakibara,Shigeki 104

Sano 135

Saur, Karl-Otto 60

Sheigo,Ando 43

Shibuya, Iwao 34

Shoii, Okuda 139

Sonobe 135

Suganuma 105

Sugiyama 27

Suzuki, Shdichi 79

Takahashi,Kijiro 91,92

Takahashi, Mijiro 97

Takaoka, Susumu ll6, 119, 120

Takeo, Tsuchii 12

Takeuchi, Masayama 62

Tamenobu 62

Tanegashima, Tokiyasu 114, ll5, ll7Tani, lchiro 6lTereoka 79

Thacker, Bob 89

Toda, Reikichi 139

T0i6, Hideki 109

Tonsho, Yoshio 105

Tsukada, Hideo 79

Tsuruno,Masaoki 69,84,85

Wada, Misao 97, I 15, I 16, I 19

Washimi,Joji 18

Wata 62

Wever, Walter 91

Whittle, Frank I 14

Yamana, Masao 71,81

Yasuda 59,60Yoshida, Kazuo l16

INDEX OFAIRCRAFT

ATHel Type He 144

AdolpheBemard'Ferbois' 67

AichiAB-l 143

AB-5 143

48-6 143

DlA 143

D3A 20,70, ll9E3A 143

El3A 75

NaryTlpe 2 143

Type lS-ko Mi-go 143

TWe H 143

Albatross D 67

Arado

Ar 196 145

Ar234 82,145

ArmvTlpeLO 50

; MHel 146

i Bachem: Ba349 Natter 106, 145

: Bartini: Stat'-6 t:t: Bell

: P-3gAiracobra l2I XP-59Airacomet ll5i Blohm und Voss

, Ha t+Z tqO

: B0elng

i B-17 Flying Fortress 93, 129

: B-29 Superfortress 15, 16, 37, 52, 74, 96, 98, 104, 106, 109, ll0, l12,

: ll5,116, |9,124,129i Brewster

: nzl t:t: Biicker

: sii t:t tqz, tqo

i Campini Caproni

I N.l l14, ll5: Consolidated

, B-24Liberator 93,112

: Curtissi P-40 warhawk l3lI nzc-t oz

r DalonWnghtRB 6?

: Deperdussin 67

: Domier

: oouz vai oo 3:5 preil tqo

: oo 6ls 146

i DocKomet 143

: oo I wd t43

, Ooru tqa

, Douglas

i c-54 sqmaster 14

: nc.qo t+, gz

: OXHet t+4

; Emi 16Fuji-go 68

, Fieseler: Fi 103R Reichenbery 62,146,147

I Fi 156 Storch I47

i Focke-Achgelis

: Fa 330 Bachstelze 147

, Focke-Wulf

I Ente 84

: nwqZ tq3

: Fw 190 123,147

I Fw 200 143

: Tal52 147

. Ta 183 79

, Fokker

I D.XXII 126

, GeeBee

:Rt0s.268: GlosterI E.28/39 1 15

: Gloster III 67

: Meleor l15

, Gotha: Go242 147

1 Go244 147

' Crumman: F2F 68

: F7F Tigercat I 25

I Hansa-Brandenburg

I W33 143

: HansGrade l7: Heinkel: HD 23 143

158 .hprNEsr SEcnor Pno.lscrs: ExpsRr[{olrrnl ArRcnntr oF THE IJA AND IJN 1939-1945

HD 25 143

HD 26 143

HD 28 143

HD 56 143

HD 62 143

He 66 143

He 70 144

He 100 146

He lll 149

He l12 144

He I l8 144

He I 19 78, 79, 146

He 162 Volksjager 60, 146

He 177 Greif 91, 108, 146

He 178 l14, ll5He 219 146

He277 146

He 280 I 15

HenschelHs 129 146

Hs 130 146

HinoKumazoHK-l 17

No,l - No.4 Kamikazi-go l7Isobe Kaizd

RumplerTaube 142,144

Junkers

G 38 144

Ju52 75,147

Ju 87 147

Ju 88 47, 81, 147

Ju 90 60, 144

Ju 160 144

Ju 290 147

Ju 390 147

.lu 488 147

K37 144

Ksl 144

Kamikaze Airplane 125

Kawanishi

Baika 61,62, I06, 147

El5KShiun 122

G9KGunzan 92

H6K 63,65H8K 63,64,65H8K2.LSeikl 63

HllKSoku 63,64,65J3K 93

J6KJinpu 84,88K-2 68

K-60 63,65K-100 92

K-200 65,66Ki.85 l4KX-8 63

NlKl Kyofu 125

NlK2-J Shiden-Kai 64, 88

TB IIOTokkoki ll5

KawasakiHighSpeedHearyBomber 47

Ki-28 68

Ki-45Toryr 9,124Ki.48 70,125,134K|-48JI otsu 133

Ki-60 IKi-61 Hein 9, 124,146

Ki-64 9, 10,49, 127

Ki-78 68

Ki.88 12, 13,49

Ki.91 14,15, 16

K-102 24,134Ki-108 16

Kayaba

Katsuodori 17, l8Ku-2 l8Ku-3 18

Ku-4 18

Ki-l28 2lKi-200 18, 19, 36,41, 77, 79, 97, 99, 100

Kirkham-WlliamsRacer 67

Kogiken

PIan ITypeAHeary Fighter 43

Plan I Tlpe A High Speed Heary Bomber 45, 47

Plan I Type A Long Range Healy Fighter 44, 45

: PlanlTypeBHearyFighter 43,44: PlanlTypeBHighSpeedHearyBomber 46,47: Plan I TWe B Long Range Healy Fighter 45

: Plan II High Speed Heary Bomber 46, 47, 48

r Plan II Light Bomber 44, 45, 46

: PIan II Long Range Healy Fighter 45

: PlanlllLightBomber 44,46,47I Plan III Long Range Heary Fighter 45

: PlanlllRevisedLightBomber 44,47,48: Plan [VReconnaissance Plane 48

: Plan IV Revised Reconnaissance Plane 48,49: Plan V Light Bomber 47

: PlanVRevisedLightBomber 45,47,48: PlanVI HealyBomber 45,47,48

: Plan Vlll High Speed Reconnaissance Plane 48, 49

i Kokusai

, Cl-Co Zt

, nle U,Vt: Ki-86Ko 21,146

i Ki.86otsu 21,146: Ki-105 Otori 63, 147

: Ku-7 Manazuru 23, 63, 147

: Ta-Go 2l, Tsu-Go 2l: fugishO

: D3Y Mydjd 20

, D4YSuisei 70

: ltqv t:s, High Speed Aircraft (DB60l) 67

: High Speed Aircraft (NKl) 67

: MX!6 69, 84

: MXYT 70,7t,72,75,76,106,124: MXY8Akigusa 77,98I MXY9Shuka i7,98, 0ur-t 72,73,7s,76

, otall'lodel | 70,71,72,7J,76, Ota MoOet Zt Zt, at, SZ

, okaModel22 7t,7J,74,76,77,91,82,|s, Oka l,loOet 3l ZZ, Zq

, Ot<a l,toAet q:l ZZ, Z+

: oka ir,todet q3g oz, 23, z4

, Ola tr,toOet qt f-t Kai Wakazakura 62, 75, 76

: oka Model 53 z4

i ltY cinga 73, 74, 81, 82, I 12, I l9, RlYl Gyoun 78

, R2Yl Keiun 78,80, 146, 148

: R2Y2 Keiun-Kai 79,80

: Tenga 65,79,81,82,83, l12

: Y-20 8t

; v-:o za

: Y-40 79

:K\TSTU: JnV Shinden 69, 84, 85, 86, 87, 88, 105

i Jnv2 shinden.Kai 88, 89, 90, 94

: KgWMomiji 146

i Kl0w 77

i Kllw 85

: x.ls 84

, Lavochkin

: u- t:t, Lochheed

I Model 1l superElectra 50I Ll1^l 144

: r-,v.c.

: D.X 144

, MacciC.202Folgore 68

Maeoa

: nn zz,z3: Manshu

: ri.zg 24

I Ki-98 24

: Martin

: 8-26 Marauder 8li Messerschmitt: Bf lo9 123, 148

: Bfll0 44,126,148

, Mel63Komet 41,59,62,77,96,97,98,124,148I Me 209 148

, Me 210 148

: Me 262 Schwalbe 34,36,59,62,97,114, l15, l16, l17, ll8, l2l,: tqa, Me 264 82, 109

, Me 309 148

: Me 323 Gigant 148

j Me 410 148

: Me 509 148

: P.l l0l 79

: Mitsubishi: A6M 68, 70, i2, I 16, I 19, 125

: A7M 94

: A7M3J Rifuku 91

, c:M st: c4\t 71,72,73.74,75,9t,92,110, G6M ilO, GTMTairan 91,92,108: J4M Senden 93, 91,95, J8M Syusui 18, 31, 36, 41, 62, i7, 96,9i, 98, 99, 100, 106, 124, 133,

| 148

r Ki-l 144

: ri-t-rr lqq

: Ki-2 t44, xi-z.u vq, fi-ZO tqq

: ri.zt z:, t:o: Ki.46 142

: ri-qo-ln qg

: fi-OZ Hlryu 81, 130, 133, 134, 135: Ki-73 27

: ri-a: zz, ri-go eo

: ri-tog tgi tt-eo gt

: tr,t.zo sl: otori qA

, Pa.400 (Payen) l0l, 103

I T.K.4 T}pe 0 101,126,127: Mizuno

Jrnrlu 105, lub

, Strinryult 104,105,106,107: Morane-Saulnier N 'Bullet' 67

:l\aKallma: nzt rct,nt,na: geN gs, trs: E8N 142

, Fugaku 65,108,109, ll0, lll, G5N Shinzan 14,92, 108, 109

: G8N Renzan 74,92, 108, l16, ll7I Gl0N I l0. ttllCekt<O ttZ, tt3, J5N Tenrai 84, 88, I 16

i J8N 122

: .lgt'l tzz: tsv tzz

'. K-27 24

Ki-44JI Hei Shoki 18

Ki-49 Donryu 70

Ki-68 14

Ki.S4Hayate 20,24,30,125,126

K-87 24,28,29,54,56Ki-87-il 30

Ki-'ll5 Hei 31,33Ki-ll5 KoTsurugi 31,32, 33, 70, ll5Ki-l l5 Otsu Tsurugi 31, 33

Ki-201 Karyu 34, 35, 36, 59, 60, 79, 94,122, 148

Ki.230 31,33Kitsuka 19,34, 79,82,89, 106, l14, ll5, l16, 117, 118, ll9, 120,

t2t, t22,125,148ProjectZ 108,109, ll0

Payen

Pa.22 101,103

Pa.l00 Fleche Volante l0lPa.10l 101,103

Pa.ll2 l0l,103Raab-Katzenstein

Rakate 84

Rammer 123,124

Rikugun

Ki-93-l Ko 37,39Ki.93-l Otsu 3i, 39

Ki-202 Sylsui-Kai 19,36,40,41, 42, 100

RohrbachR 144

Roland'Walfisch' 67

S-31 Kurorvashi 129, 130

Savoia-Marchetti5.65 67

Showa

Toka 31,33,70, 106, l15Supemarine

s,5 67

Spitfire 68

JeplnEsE SEcRrr PnorEcrs: ExpsRrN,rENreL ArRcnapr oF THE IJA AND IJN I 939-l 945 159

Type 300 68

Suzukaze 20 l0l, 102, 103

Ta-Go 20,21

TachikawaKi-g 105

Ki.74 50,51,52

Ki.74.ll 52

Ki-77 50,51

K-94 24,25

Ki-94-t 53,54,56

Ki-g4-tr 55,56Ki.l06 20

Ki-I62 59,60, 146

Plan I High Speed Heary Bomber

Plan II High Speed Heary Bomber

Plan III High Speed Healy Bomber

ss-l 50,51

Ta-Co 2lT.K.l9 101, l3lTdkyo KokuKi.l07 2l

TupolevTu-2 82

Tu-12 82

Type Hansa.3l0 143

VickersWellington 8l

YokoiKu-13 i7

Zeppelin

Rammer 123,124

INDEX OF ENGINIS

AichiAEI Atsuta 68

Ha-70 79,80

BMW

003ASturm 89, ll5Daimler-Benz

DB601A 10,43, 4s, 68, 78, 79

DB605 43

de Havilland Gipsy 18

Gnome-Rh6ne

7KD Titan Majot l0ll4KMistral Malor 68

GIRD-01 17

HeinkelHeS I ll4HeS3 l14

HeS011 ll5,149Hitachi

Ha-13 Ko 2lHa-47 21

Hatsukaze 74

IshikamjimaNe 130 36,82,89, 115,120,122

Kawasaki

Ha-40 10,43

Ha-140 12, 45,47, 49

Ha-201 10,47,49

Kayaba Model I l7JunkersJumo004 82,9i, l15

Jumo 9-21 I 82

KRl0 18, 41, 98,99, 100

KR12 98

KR20 41

Kugish6

Ne20 18, 59, 62, 65, 74, 82, 89, ll2, I 15, I 16, I 17, ll9, 120, 122

Maru Ka-10 61,62

MilsubishiHa-l0l 14

Ha-I04 Ru 51,52

Ha-lllM l4Ha-20311 27

Ha-2ll 37

Ha-2ll-l 51,52

Ha-2ll-ll 43,45,46,47,49

Ha-2l1lll 24

Ha-21 IMB 48,49

Ha-2ll Ru 25,51,52,53,54

Ha-214 14, 37,39, 47

Ha-214M 50,51

Kasei 12 14

Kasei 25C 8lMK4Q Kasei 22 63,64

MKgA 8IMKgD 84, 93,94

MKI0A 78,92

Ne330 59,65,79,80, ll5, 120, 122

Nakajima

Ha-39 44,45,46

Ha-44 109

Ha-45 43,44,45,47,48

Ha-54 109

Ha-I03 l4Ha-145 44,45, 48

Ha.219 55

Ha-219 Ru 28

Homare I I 8lHomare l2 8lHomare 23 81

Ne 230 36,82, 112,115,122

NKlBSakaell 68

NKTAMamorull 14

NKIIA 109

Sakae 2l I 12

Sakae 22 I l2Ne l0 59, ll5Ne 12 59,82, ll5, I 16

Ne l2B 59, 74,84, I 15, I 16, I l7Ne 30 82

NihonHainenkiSemill 69

Nu 91,92Rolls-Roy'ce

:'Jene-l 82

Toku-Ro.l 105,106

Toku-Ro.2 41,98,100

Toku-Ro.3 41,133

TRl0 l15

Tsu-ll 71,73,74,77, l15

Tlpe 4 Mark I Model 20 70, 71, 74, 124

WaltherHWK509A 96,97,98

HWK 509C 41

YokosukaYE3 129

INDEX OF WEAPON SYSTEMS

(as presented in the book)

ASM-N-2 Bat 132

Blohm und Voss BV 246 Hagelkorn 148

Brakemine 132

E77 140

EMWA4 132, 148

EMWC2Wasserfall 132

Fairey Stooge I 32

Fieseler Fi 103 132, 149

Fu-Go 108, 139, 140, l4lFunryu I 132

Funrp 2 132, 133

Fun4m 3 133

Funryu 4 133

GB.1 132

GB"4 132

Henschel Hs I l7 Schmetterling 132

Henschel Hs 293A 132, 149

Henschel Hs 294 149

I-Co-l-A 133,136

I-Co"l-B 133,136

I-Go-1-C 134

JB series 132

Ke-Go 134,135,136

Ki-l47 133,136

Ki-148 133,134,136Ki-149 134

Ko-Dan 137,140,141

Korolev Tlpe 2l2A 132

Kurai Aerial Torpedo No,6/No.7 134

Little Joe 132

McDonnell LBD-l Gargoyle 132

Mk.7 137

Mk.19 137

Rheinmetall-BorsigRheintdchter 132

Ro"Ta 138

Ruhrstahl-KramerX-l FrilzX 132, 149

Ruhrsahl-KramerX-4 132, 149

Silver Paper Scattering Bomb 137

SS-l Scunner 132

Syisuishiki Kayaku Rocketto 124

Ta 137,140,141

Ta-I05 137

To-2 138

To-3 137

Type 2 No.6 2l-Go Model I 138

Tlpe 2 No.6 2l-Go Model 2 138

Tlpe 3 No.6 Mk.3 Model I 138

Tlpe 3 No.6 Mk.27 Model I 138

Type 3 No.6 Mk.28 Model I 138

Type 5 No.25 Mk.29 138

Tlpe lOCh 132

T1pe 99 No.3 Mk.3 Sangd 138, 140, l4lv-l 132,149

v-2 132,148

VB.I AZON I32

VB-6 Felix 135

47,48

47,48

47,48,49

160 JeptnEss SEcnnr PRo:ecrs: ExpsRIMslNral Alncnanr oF THE IJA AND IJN 1939-1945

THE AUTHOR

Edwin M. Dyer, born 1969, has studiedmilitary technology for over 20 years,concentrating on weaponry from l9l4through 1960. In 1999, he created theHikoki:1946 website, highlighting Japaneseexperimental aircraft. In his spare time heis a World War 2 reenactor, attendingpublic events with his extensive militarycollection throughout the spring andsummer seasons. He is currently serving inthe United States Civil Air Patrol with therank of Master Sergeant.

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Kugisho \1\l tiilrr K:r_-,-i '.1\':, i..,',i -iit.tll it\pciinlentarl alircriift, desiqncd k) flight test thc Ito|iliLil1.L1l r:-,,..:: r',ir-!(i ontlle\alr"s.J7\VShintlenfiglltcr.Thr-'t:tlrarrtplesnelebuilt.t\\orlirr:r-::i:: :::iirr)i.Jr tlidcrrrilltpushercnginoarrangenlcllt. Iheprofilositorrsoncot tlrr -.,r:. - .- ,.. i' :r)LlirLl i;r a derelict state at Atsugi airfielci altei thtl.l;t1;anese surtencler

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clrlirrr-. tlrc .ailtr enqine tlr;it \\'as used in thc calh'\larr mo(icls of tl)e fanlous \lcsscischntitt1011. Ii oir ir irih it \r'JS r lot the Nar t' ltr rt thc Armt' Air Foicc that e\ enttlalh \\ ould use a iicensc-bLriit r.t ,ion of this engine in thcir Ki'6i Tonrj figlrtcr. The \an' stuck to th€) Itloxl reliiiblcra.li,1l !ir!inei foi tlrt:ir figlttct fbrce.

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