A History LessonWalter Extra designed aerobatic light air-

craft from the outset for unlimited aerobaticcompetition flying. The original woodenwing Extra 230 was designed by Walter tomeet the requirements of competition pilotswithin the Swiss Aero Club. First flightoccurred during 1983. Unusually for an air-craft of its type, the Extra 230 features awooden wing with Dacron covering, while ason other aerobatic competition aircraft the230's wing has 0∞ incidence for sustainedinverted flight. Production of the 230 ceasedin 1990 when Extra was experiencing diffi-culties in sourcing the correct type of wood.Design work on the larger, two seat Extra 300began in early 1987, culminating in the firstflight of a prototype on May 6 1988 and cer-tification in May 1990. Production began inOctober 1988.

Small numbers of Extra 260s were alsobuilt in the early 1990s. These aircraft wereessentially downsized Extra 300s with seat-ing for a pilot only and powered by a 195kW(260hp) IO540 flat six. The Extra 260 was notcertified and the six that were built wereable to fly only under special permits.

The single seat Extra 300S first flew onMarch 4 1992 and was certificated that samemonth. The 300S differs from the 300 in hav-ing a single seat, shorter wingspan and morepowerful ailerons, while retaining the samepower plant and basic fuselage. The 300L hasa low mounted wing. The strengthened 330Lhas a 245kW (330hp) AEIO-580 and largercontrol surfaces, and first flew in January1998.

Throughout its evolution, and variousforms, the Extra has featured in world cham-pionships around the globe and has earnedits place as one of the most capable aerobat-ic aircraft on the planet.

Precision Aerobatics Extra 330LI guess any aircraft that has so many vari-

ations and the capability of unlimited aero-batics as well as the inherent stability of thisaircrafts design features, is going to be a pop-ular plane to model, particularly for thoseIMAC, 3D and freestyle junkies. It is to dateavailable in many models of all sizes, and allconstruction types.

I first laid eyes on the Precision Aerobatics35% Extra 330L some time ago whilst visitingPA on another matter. I have to admit, myknees went weak and I believe my voice mayhave squeaked like an adolescent. It was justlike the first time I laid eyes on mywife…..love at first sight. If the shear size ofit isn’t enough to impress you, the lines, flair,colours and overall quality command a pres-ence that is hard to ignore. Despite theseaspects of this model though, the thing thatimpressed me the most was the construction.When the hatch is opened, what greets theeye is nothing short of a work of art. Theintricate interlocking and tight fitting of parts,the well thought out gear trays and general

layout all point to a well researched andplanned model. This should not be surprising asthe plans for this particular aircraft havestretched over some 4years and has been alabour of love for the company over that time.

I will talk more in depth about the flying alittle later, but lets just say from the outset thatthis is a serious competition model. Designed toexcel particularly in freestyle, it has raised evensome very hard to impress eyebrows. BillHempel, a well known competitor from theStates has had one, and loved it so much, heoffered to provide PA with a video. Sadly onlyone video was captured before it died prema-turely due to radio failure and that was an earlysetup flight, before he started to “wring it out”.Young Kyle, “The Alien” also from the stateshas electrified his one, and his video can alsobe downloaded of the Precision Aerobatics Website. It should be noted that Kyle’s’ video isactually the maiden flight, taken at the end of acompetition weekend and his CG wasout…(don’t know which way, just “out”).Viewing this particular footage will indeedmake you love the plane (and hate thepilot…….and any other young punk who canfly a plane like that….) And to top it off two ofthem will be entering this years up and comingTucson Shootout, one of the worlds most pres-tigious annual aerobatic events held in theStates. My point? This is a serious aircraft withserious potential, not your average “large ARF”that’s been up-sized to take a 100cc engine.

The Set UpThere are several things to consider when

setting up a large scale plane with multiple ser-vos that are ganged to provide lots of torque forthe big control surfaces. Firstly, there’s thepower supply. Running 8 high torque, powerhungry digital servos along with a ninth servofor throttle and a tenth signal to a smoker etc, allneeds good reliable power and plenty of it. I

chose to use 2 x 7.4v 2200mAh Lipoly batteriesrun through a power regulator in tandem. Ofcourse this amount of current cannot be traf-ficked through your receiver so some sort ofpower distributor is going to be required. Themuch acclaimed Emcotech Mini RV5 was chosenas it accepts power from the two batteries andsends it directly to the servo along with the sig-nal from the receiver. The Mini RV5 has manymore features of course but that’s a review all ofits own. All I’ll say for now is this unit isdesigned with safety in mind and has backupover backup. Now down to servos. Hitec was onthe menu, so 4 X 5645MG working in pairs wereused on the ailerons, and 4 X 5945MG used onthe rudder and elevators. The latter are very fastat 0.13 sec/60 deg and stall at 13kg. I wouldconsider using these all round on the next oneas I believe they are worth the extra money. Amighty mini was used for the throttle.

The kit comes without hardware which iscommon on a plane such as this, as many mod-elers have their own preferred ways of settingsomething up. PA have however, put together ahardware package that not only has very highquality components, but is offered to Extra cus-tomers for only $168. This is incredible value asthe items would add up to over $300 if boughtseparately elsewhere. The ball links are Germanmade, as is the pull pull rudder cable pack. Allnuts, bolts, pushrods, servo horns, control horns,etc are all included. They have also made avail-able a package containing all the extension leadsrequired and another to include all plumbing.The extension leads are heavy duty with spiralwound wires to reduce noise emission, and theplugs are high contact to reduce voltage drop. Inow use these leads on all my aircraft. A veryattractive offer is made for those that wish to pur-chase the 3W or DA options as well.

At the business end of my Extra, a ZDZ 80ccengine was chosen exhausting through a JMBcanister. Bolted to the spinning end of the ZDZis a Mejlik 26 X 10 prop finished with a beauti-ful carbon fiber spinner. A Simplex smoke sys-tem completes the set up. For weights sake, theoptional Carbon Fiber wing and stab tubes werepurchased along with some very nice purposemade PA wing bags.

The BuildI will state from the outset that this was my

most enjoyable build to date, but more about thatlater. The instruction manual is one of the bestI’ve seen with very clear photos and goodmethodology. It goes without saying that a modelof this size is more than an evening’s work to puttogether. This is indeed a project to be taken seri-ously with thought and patience put into everystep, however some have reported building it inno more than four days! Due to the size andnature of the model, I’m not going to go on toomuch about how each step is followed as thisreview needn’t be an instruction manual of itsown, rather I’ll describe the process as a whole.

Essentially the build itself is not much morecomplicated than the everyday 60-90 size ARFin that all the intricate hard work is done foryou. However as with any large scale plane,there are some additional things to be takeninto consideration, such as the vibration of a 9-10HP motor that’s going up front, the copiousamount of force required to deflect those largecontrol surfaces, and the high G forces you areno doubt going to inflict on the model. Forinstance, a snap roll can pull around 17G (sub-jective of course), so that custom made batteryrack you want to install (not that you need to in

this model), needs to be able to take not200grams, but 3.4kg plus. Those push rods andlinkages all need the same consideration.

The other notable difference with a buildsuch as this is that everything is designed to lastforever, therefore each step of the build needsto be approached from that angle. For example,I know of many large planes like this that outlive the servos, whereas on your smaller mod-els, it is almost always the other way around.This means that each item must be installed ina very permanent fashion; extension leadsshould be cable tied, heat shrunk, and evenloomed where necessary; all nuts should bethread locked etc. Do not be afraid to also goover the entire airframe to check glue joints andother crucial aspects. Remember, even the high-est quality plane becomes 100% your responsi-bility once it’s airborne. Therefore take carewith each step.

There are several unique aspects to this par-ticular kit, one being the double carbon fiberglued in control horns. These have been care-fully designed to maintain good geometry, withthe pivot point directly in line with the hingepoint. They fit into slots and epoxy into place,becoming an integrated part of the control sur-face. With a ball link fitted between the twoparallel horns, an extremely rigid and strongconnection is achieved. The elevator servos aremounted inside the stabilizer and are accessedthrough the root rib. This again allows for goodgeometry eliminating the need for the push rodhaving to run through two opposing arcs. Thecontrol surfaces are hinged with point hingesand come pre drilled and trial fitted. All that isrequired is to remove and epoxy each one inthe usual fashion.

With my particular set up, using the ZDZ80cc I made the choice to alter things a little,adding 27mm to the fire wall (thereby movingthe engine forward by the same amount) andmoving the rudder servo tray forward one bay.

This was to achieve the correct CG with thelighter power option, especially with a canisterthat has its own center of gravity which sits fur-ther back than a Pitts style. This particularaspect is often counteracted by the extra weightof the canister and header, but still something toconsider when setting up a model of thisnature. Bear in mind that set up with the DA100 or similar, these changes are not necessary,but don’t be afraid to personalize a model likethis if you feel the need or have reason to.

The kit comes ‘canister ready’ which is animportant option for many these days withmore and more emphasis on noise and therestriction there of. However, because thismodel is designed to take a large range ofpower and muffler options, there is most likelysome additional work that will be required ifinboard canisters are used. It really depends onwhat you decide to fit in there and how youwant to set it up as to the work you may needto do. A look on the build and support forumon RCU will give many examples of the differ-ent ways of accomplishing this, so there reallyis no guess work. Being of wooden construc-tion, any work you choose to do is delightfullysimple and the easy access from the top alsohelps. On mine, I moved the fuel tank tray upfor the canister, (I believe subsequent produc-tion runs will have this as standard) and backover the wing tube to allow room for smoketray and then boxed in the compartment below.

The Emcotech Mini RV5 was installed on themore than adequate gear tray, using four sili-cone tube stalks to absorb vibration. Anotheraccepted method to do this is to build a sepa-rate tray and string it off four rubber bands thatspan the model. High current power leads runfrom the two LiPo batteries up front to thepower unit and charge leads are piggy backedoff those leads. I used standard 2.5mm powerplugs from Dick Smith Electronics as they fitteddirectly into spare fuel dot holes in the fuse.The unique digital remote on/off switch sup-plied with the Emcotech fits into the standardcutouts on the fuselage.

Servo installation is fairly straight forward,but again, be sure that connections are securedand clipped, and leads are zip tied to the air-frame. To get those impressive 3D rates out ofthe control surfaces, I used the PA carbon fiberservo horns that are included in the hardwarepack. There are other options out there, butbeware of a couple of things. Most importantly,when using footed ball links, the enormous off-set side loading can cause a twist flex in thearm. I have encountered this before on severaltypes of long arms and while it doesn’t neces-sarily lead to the demise of your model, it doesaffect performance and is in every way undesir-

able. Carbon fiber on the other hand is far moreridged and is able to resist higher twist forces.The other thing I like is the fact that you can tapout the hole and screw in the center bolt andthen lock nut it in tight. The ball joints thatcome with the optional hardware pack aremade in Germany and are of the highest quali-ty. Again, these are very critical items and noshortcuts can be afforded.

As I said at the outset, this is by far the mostenjoyable build I have had to date. All the hardwork is done for you, which sets this aside frommost on the market. The slots are there for thecontrol horns, the holes are there for hingepoints, switches, fuel dots, and vents. The place-ment of all these are well thought out and thegeometry for each is spot on. Working out yourown geometry can take hours, so it’s an impor-tant feature to have that done for you. While thisExtra could be built in just a few days with gooduse of time (and without my particular mods) Iwas happy to take my time and savor the expe-rience. The high quality of all the componentspromotes a high standard of set up, so enjoy it.

ProgrammingSix of the nine servos are ganged into pairs

so it is very important to synchronize them.With the Hitec digitals, a programmer can bepurchased to take care of that. Others utilizematchboxes or the like to achieve this, butwhatever is used, they need to be synchronizedto stop them fighting each other. Huge amountsof current can be drained not to mention thestrain on the servos if this is not done properly.The next step is to set the end points or deflec-tion of each control surface using my 3D prothrow meter. On mine I set the elevators to 40degrees up and down for high rates, aileronswere 35 and rudder was 45. All dual rates wereset to 30% for low rates and 60% for mid rates.I always set the expo so that the central 1/3 of

the stick has similar throws in all three settingsto allow smooth flying in all flight modes. Thisis a personal choice that works for me, but ofcourse everyone’s different.

The FlyingFor me, the test flight date came on the

8/09/06. Arrangements were made for a friendof mine to meet me at the field, for safety’ssake, and to be my “wheel chocks” for the runup. As usual with a model of this nature, I set itup at the field and conducted a thorough pretest flight check. I don’t mind spending a cou-ple of hours on this if need be before the maid-en flight as there are several things that shouldbe carefully checked. It may sound silly, but itcan be the simple things that catch you out. Ihave seen models go down on maiden flightsfrom things like engines coming loose becausethe bolts were not tightened properly, extensionleads coming out of servos, batteries comingloose, wheel axles coming loose and even servocontrol horns screws being left out. The latterhappened remarkably easily. The builder hadpush fitted the horns on ‘temporarily’ until theservos were powered up to check that theywere central, he just forgot to come back to it!While perhaps most of us who have been onthe hobby for many years have lost a model dueto some sort of neglect at the building stage, forthe sheer safety risk alone, as well as the invest-ment, one really does have to be sure on amodel like this. The last thing I re-checked wasthe CG…….bang on center of wing tube (thiswill no doubt be pushed back later).

Once I was comfortable with everything, theengine was test run again, batteries weretopped up, and she was taxied out to the flight-line. The ZDZ running through the JMB canistersounded great on the taxi way, a mixturebetween a deep but quiet rumble and a throatygrowl. I have to admit, on the maiden flight ofany giant scale, I always need to take a coupleof deep breaths before opening the throttle. Shewas opened up, and after a takeoff roll of about3metres, she was well and truly airborne andtracking straight ahead with only a couple ofclicks to the right. What a plane! I had heardothers speak of how nice this thing was to fly,but it has to be experienced to be believed. Sheflies so light, it’s incredible. The ZDZ 80 hadbags of power and plenty of authority in thevertical, and seemed to handle the stop/starts inthe up lines with out any trouble. This was thefirst flight, so not to tempt fate, I kept it to fair-ly sedate routine. Landing was effortless, but Iwas caught out by the distance it floats once inground effect, and I used more ground than Ianticipated. Landing roll was about Ω that oftakeoff, and ground speed was extremely slow.

I gave it a quick check over to make surenothing was about to fall off, wings and stabincluded, then three more short flights fol-lowed. As the light was failing, and the nastycross wind was picking up, we all thought itbest to wrap it up and leave the “trainingwheels” on till next weekend.

The next weekend . . . . .WindyThe weekend after that . .RainyThe one after that . . . . . .Windy & rainyI’m sure most of you can relate to the

agony of sitting by the window and lookingout at flight inhibiting weather, but threeweeks??! Come on! While I was house boundthough, quietly rethinking my recent decisionto move from Australia to New Zealand,where the grass is always green…(‘cause itdoesn’t stop raining) ….I made a few smallalterations. I moved the CG back some15mm, stripped out a little bit of weight thatdidn’t justify itself, and reinforced the firewall with small bits if aluminum angle. Thelatter was done purely on account of theamount taken out of the ply firewall to fit thatbig ZDZ carby through, and would be unnec-essary on other installations. Lastly I wentover the covering again with an iron to getrid of a few wrinkles. It is covered with highquality Oracover, but even that sometimesneeds a bit of work till it’s acclimatized.

Finally some good weather came ourway...(pheeeew)… and eager as a beaver Iwas out there, Extra under my arm….wellthree trips with both arms really. Anyhow,time to wring this baby out. Despite the factthat everything had been checked, rechecked

and triple checked, over the past 3 weeks, aquick pre flight was conducted before taxiingout (the full size boys do it and so shouldwe). This time there was no holdingback…and boy did she perform! Walls werea heart stopper, harriers were super easy,hovering, it does it all with ease. As this planeis built primarily around freestyle parameters,it performs 3D like a natural. OK, it wasn’tquite the same as “The Alien”, Kyle Woyshnisvideo, but that’s partly the pilot I’m sure. TheZDZ 80cc with the Mejlik puts out 50lb ofthrust and the plane weighs 25lb. This givesa thrust to weight of a healthy 2:1, but I knowothers that want more. In any case, pullingout of a hover was a snatch, holding a knifeedge was beautiful, including high alpha, andwaterfalls were a piece of cake. Rudder cou-pling is non existent, (but that does dependon the CG placement) and rolls are nice andaxial. A little bit of rudder may be mixed into throttle later but certainly not a big prob-lem, and again this is affected by individualset ups, such as prop size and pitch.

All in all, this thing is a winner and I don’tbelieve anyone fortunate enough to acquireone would regret it. A comment often madeabout this plane is that “it’s a 35% that flieslike a 42%” which is testimony itself of itsattributes. It is the lightest aircraft with thebiggest wing area in its class and I would bequite happy to let go of all the other planes inthe hanger and settle for this baby, it does itall. If you are in the market for a big, serious-ly aerobatic aircraft, I would have no reserva-tions recommending this one to anyone.