page-tighas (r. 9-(o
TRANSCRIPT
OPEN-WATER AND CAVITATION PERFORM4ANCE
OF THE PROPELLER FOR AOE-1
by
W. H. Roundy
HYDRCMECHANICS LABORATORY
TEST AND EVALUATION REPORT
October 1962
*~ ~-(-" ~ II~ ~- ua~ ~- I -I ^--- lilar**x1
-- i l 1 1 I ll
Report 1670
TABLE OF CONTENTS
Page
ABSTRACT ............................... 1
INTRODUCTION ............................. 1
RESULTSANDDISCUSSION ........................ 2
REFEENCES .............................. 3
LIST OF FIGURES
Figure 1 - Drawing of Model Propellers 3924 and 3925 . ......... . . 4
Figure 2 - Open-Water Characteristics of Model Propellers 3924
and 3925 . . . . . . . . . ......................... . 5
Figure 3 - Visual Observations of Cavitation On propeller 3924 . . . 6
Figure 4 - Photographs of Back Cavitation on Propeller 3924 ...... 7
Figure 5 - Photographs of Face Cavitation on Propeller 3924 . . . . . 9
Figure 6 - Inception Curves of Visible Cavitation on Propeller 3924 . 10
Figure 7 - Variation in Thrust and Torque Coefficients with CavitationIndex for Propeller 3924 . . . . . . . . . . . . . . . . . 11
Figure 8 - Cavitation Characteristic Curves of Propeller 3924 . . . . 1
"m~~1~331*- 11*~11 .... .. .--.--. -fi~*-ill rra*~ srm-*r~--r~---- ----arr- m~-~ I
---------- IYIIIIYIIIIIYIIIIYYIYIIIIIYIII iilir . I m
NOTATION
bo.7 Blade section length at 0.70 radius
D Diameter of propeller
e Propeller efficiency, e KtJK *2iq
g Acceleration of gravity
vaJ Speed coefficient, J =
Tn'DKt Thrust coefficient, Kt T 4
Kq Torque coefficient, Kq = pn D
n Revolutions per unit time
P Pitch of propeller at 0.70 radius
p Static pressure at centerline of propeller
Py Vapor pressure
Q Torque
R Propeller radius
r Radial coordinate of propeller
Re Reynolds number, Re b_ V -- (0.7"**n*D)2e V
T Thrustva
V Ship speed, V - - w
Va Speed of Advance
W Average wake fraction
x r/R
v Kinematic viscosity
p Density of water
a Cavitation index, a = -
%*p v2
iii
-- 11111
IM !Ilum ' I11I il, I. IM , -W0 0 -
ABSTRACT
Test results are given for the predicted cavitation performance
in uniform inflow of the propeller designed for AOE-1. These results
are shown as inception curves of face, back, and tip vortex cavita-
tion at each design radius of the propeller. Open-water and cavita-
tion characteristic curves are also included.
INTRODUCTION
As requested by BuShips,1 a pair of model propellers (No's. 3924 and
3925) were constructed to correspond to the propellers designed for AOE-1.
Drawings and dimensional characteristics of these propellers are shown in
Figure 1.
Tests were conducted in the deep-water basin using the TB propeller
boat with 1/4-horsepower pendulum dynamometers to obtain the open-water
characteristics of both the right and left-hand propellers. Each propeller
was tested over a range of speed coefficient J, with constant rotative
speed of 13.2 rps, except at low values-of J where rpm was limited by the
capacity of the dynamometer. The open-water characteristic curves are pre-
sented in Figure 2. The open-water test was conducted at a Reynolds number
of 3.5 x 105. A check test conducted with the new 1-horsepower dynamometer
at Reynolds numbers between 3.5 x 105 and 5.9 x 105 showed no measurable
effect of Reynolds number on thrust and torque.
The right-hand propeller was tested in the 12-inch variable-pressure
water tunnel in uniform flow using a transmission type dynamometer to deter-
mine the cavitation characteristics. The test was conducted over a range
of J values from 0.4 to 1.0 in increments of 0.1 with constant angular
velocity of 26.0 rps. However the test at a J of 0.4 was run at 24.0 rps
with a corresponding lower water speed in order not to exceed the load
capacity of the dynamometer.
References are listed on page 3.
- -lo i gimillulikii
IIUU
" II 1 11, A 1111 16 ' d 6 1111
The tunnel water speed was adjusted so that the thrust with atmospheric
pressure in the tunnel was the same as that obtained from the thrust coef-
ficient Kt from the open-water curves for the same J. As the tunnel pressure
was decreased to the minimum (3.5 feet of water) by small increments of from
one to four feet of water, the thrust, torque, and pressure were measured.
When cavitation was visually observed, photographs were taken and a sketch
was made showing the type and extent of cavitation present. Sketches of
cavitation at selected values of cavitation index for the speed coefficients
tested are shown in Figure 3. Sample photographs of the cavitating propeller
are shown in Figures 4 and 5. The cavitation test results are shown in
Figures 6 through 8.
RESULTS AND DISCUSSION
Cavitation inception curves are given in Figure 6. These curves were
obtained by plotting the radial extent of cavitation as determined from the
visual observations against a for each value of J. At each J value
limiting values of a were determined from this family of curves for incre-
ments of 0.1 of the normalized radial distance x and plotted against J in
Figure 6.
These curves thus indicate the limiting value of a for the inception of
face, back, and tip vortex cavitation. That is, the area above any curve
indicates that there is no visible cavitation of that type present at the
radius indicated on the curve. Below the curve at this radius, the intensity
of cavitation increases with a decrease in a. When using this curve, the
speed coefficient and cavitation index are first computed for the desired
operating conditions. The type of cavitation will be determined by J and
the intensity of that type of cavitation will be determined by a. For
instance, with a J of 0.60 and a of o.0, back cavitation would extend from
0.5R to the blade tip. The tip vortices would also be visible.
In addition to determining the inception of cavitation, the thrust
and torque coefficients Kt and K were obtained and plotted against a for
each J tested and are included in Figure 7. A dropping off of any of these
curves from a straight line at low values of a represents a loss in thrust
1- 11111111 11
~~a~ r~rr*~,^--~~---TA9~ W~ll~~~ ----- ~R"~~""r
or torque due to cavitation. The a for the point of change gives an indica-
tion of the highest operating speed without any performance loss for the J
indicated. The cavitation characteristic curves were derived from these
curves by plotting coefficients of Kt and K for discrete values of a
against J. These curves are presented in Figure 8.
When extrapolating any of these data to ship conditions, the standard
pressure correction factor2 for the 12-inch water tunnel should be applied
to the ship cavitation index; i.e., the ship pressure p-pv should be
reduced to 85 percent of its actual value.
REFERENCES
1. BuShips ltr AOE/9440 Ser 644-173 of 6 Mar 1961.
2. Bowers, W. H., "The 12-Inch Variable Pressure Water Tunnel
Propeller Testing Procedure," David Taylor Model Basin Report 505, page 22,
(Nov 1943).
C1- " I " I~~ -- I--~ n
PROPELLERS 3924 & 3925
NUMBER OF BLADES...6 DIAMETER....... 8.697 Ins.
E.A.R. ........ 0.661 PITCH At O.7R...8.821 Ins.M.W.R . ........ 0.216 ROTATION ..3924 R.H. 3925 L.H.
B.T.F......... 0.045 DESIGNED BY BUSHIPS
P/D At 0.7R . 1.014 TESTED FOR BUSHIPS
RADOZ PIT'CH CURVEINCES myicN Es
100 4.3"1', .. 78O0WR-- -)
9S 1W I ----- - x 99 y
D 1497.;
70 3.0 ##3
S2.17 ECTED OUnJLE
40 1739- ,
37--BW .O
2D 'AM-- - - - - -.003
'Figure 1 - Drawing of Model Propellers 3924 and 3925
v e.$ -To Iu.v Ipsbeh= 2.2 to 13.2 rps
S0.0 R_ = 3.5 x 05
(0 .........
KtCA-
" 0.3
UDJ -
U) 0 1 . . . !0 . . . .:.aC-, DESI GN J
=0. 80 1 .
0 .3I C.2 0.3 0.1 _ 0.5 0.. 0.7 .C C.9
SPEED COEFFICIENT J
Figure 2 - Open-Water Characteristics of Model Propellers 3924 and 3925
0.4
0.5
0.6
0.7
0.81
7.2
4.04.0
1.6
0.9
0.9 .
0.7
0.9
0.7
1.0
1.8
CAVITATION INDEX a
1.2 2.2
2.6 3.6
CAVITATION INDEX
Figure 3 - Visual Observations of Cavitation on Propeller 3924
-6-
10.2
7.2
5.0
2.0
1.2"
1.2
16.2
10.4
7.2
,3.7
1. 6
22. 1
15.3
" i mW4---- -- ,I -1.111 -- 111, -1- -- l-, - - - --- -- ))
9.5
6.5
3.2
4.8
a= 22.1 a= 16.2 ca= 10.2 u= .Z
J= 0.4
= IS.3 a= 10.4 r= 7.2 a= 4.0
J = 0.5
Figure 4a - Photographs of Back Cavitation on Propeller 3924
-7-
_ __ --- - -~-- _~ L-~T ~=-----------~---- ----
- CP=n~-__ _1_.1_, ---
a= 7.2 a= 5.0 a= 2.7
J= 0.6
a= 0.9o= 2.0 o= 1.6 a= 1.6
J= 0.7 J= 0.81
- Photographs of Back Cavitation on Propeller 3924
-8-
Figure 4b
a= 9.'5
or= 2.7 a= 1.7 a= 1.2 a= 0.7
J= 0.9
o= 3.6 o= 2.6 a= 1.8
J= 1.0
Figure 5 - Photographs of Face Cavitation on Propeller 3924
-9-
j__ __ _ __, I r _ I - ~P~-a~-~R~ pF-~-~n";~F^~ ~Y _ ~~- -~t
~ -L-- IP--F- - ~--- P~--- ~1
40
38
36
34
32
30
26
24b
Z 20.O 7 Area of
8No Cavitation18
14
12
10
+ + ,
OPERATINGCONDITION op
2 00 . K , " .. -X = .4.
Back Cavitation --Face Cavitation
0.4 0.5 0.6 0.7 0.8 0.9 1.0
SPEED COEFFICIENT J
Figure 6 - Inception Curves of Visible Cavitation on Propeller 3924
-10-
711111311111~~ __ ~_~ _~_
4 8 12 16 20 24 28 32 36 40
CAVITATION INDEX a
Figure 7a - Variation in Thrust and Torque Coefficients withCavitation Index for Propeller 3924
-11-
-- --- -'~ YIYIIYII IYII YIYI IIYIII YIIIUYllliiirlu-
Kq
=
Kt .J = 0 0
~J= 0.40
___ ___~_~_____~.___~._______..~_ l~.~l.~ss. .... ~...~~~~~c~l~-~--~-mr- --- - -.r~- ~,--- l~-
llir ii
. 35
.30
.20
.15
. 10
.35
.30
.25
.20
.15
. 10
.35
.30
.25
S.20
.15
10N 050.35.30
.25
.20
.15
.10
.05
00 4 8 12 16 20 24 28 32 36 40
CAVITATION INDEX o
Figure 7b - Variation in Thrust and Torque Coefficients withCavitation Index for Propeller 3924
-12-
Kt J= 0.70
Kq
J= 0.81
oKt
OO , E J t J=0.91JKt -V
Y~llmh lllm
~ r rur*r a~~~~ ^3~"~~~~ n n-- rrm~
IIIl
0
U
0U
-13-
0. 7
0.6
0.5
0.4
0.3
0.2
0.1
0. 3 0.4 0.5 0.6 0.7 0.8 0.-9 1.0
SPEED COEFFICIENT J
Figure 8 - Cavitation Characteristic Curves of Propeller'3924
~q lllll ---- - --- -~--~n~*x"J~'
INITIAL DISTRIBUTION
Copies
8 CHBUSHIPS
3 Tech Info Br (Code 335)
1 Lab Management (Code 320)
1 Prelim Des (Code 420)
1 Hull Des (Code 440)
2 Prop, Shafting & Brng (Code 644)
10 ASTIA
2 CHONR
1 Library (Code 740)
1 Fluid Dyn Br (Code 438)
I -- - I - - I~C~- ---~-- -
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEF-
WA
TE
R A
ND
C
AV
ITA
TIO
N P
ER
FOR
MA
NC
E O
F T
HE
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OP
EL
LE
R
FOR
AO
E-1
, by
W.H
. R
ound
y.
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196
2.
iii,
14p.
il
lus.
, di
agrs
., gr
aphs
, ta
bles
, re
fs.
UN
CL
ASS
IFIE
D
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
per
form
ance
in u
nifo
rm i
nflo
w o
f th
e pr
opel
ler
desi
gned
for
AO
E-1
. T
hese
resu
lts
are
show
n as
inc
epti
on c
urve
s of
fac
e, b
ack,
and
tip
vort
ex c
avit
atio
n at
eac
h de
sign
rad
ius
of th
e pr
opel
ler.
O
pen-
wat
er a
nd
cavi
tati
on c
hara
cter
isti
c cu
rves
are
als
o in
clud
ed.
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEF-
WA
TE
R A
ND
CA
VIT
AT
ION
PE
RFO
RM
AN
CE
O
F T
HE
PR
OP
EL
LE
R F
OR
AO
E-1
, by
W.H
. R
ound
y.
Oct
196
2.
iii,
14p.
il
lus.
, di
agrs
., gr
aphs
, ta
bles
, re
fs.
UN
CL
ASS
IFIE
D
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
pe
rfor
man
cein
uni
form
inf
low
of
the
prop
elle
r de
sign
ed f
or A
OE
-1.
The
sere
sult
s ar
e sh
own
as i
ncep
tion
cur
ves
of f
ace,
bac
k,
and
tip
vort
ex c
avit
atio
n at
eac
h de
sign
rad
ius
of t
he p
rope
ller
. O
pen-
wat
er a
nd c
avit
atio
n ch
arac
teri
stic
cu
rves
are
als
o in
clud
ed.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
n--
Mod
el t
ests
3.
Pro
pell
ers-
-Des
ign-
-M
odel
tes
ts4.
P
rope
ller
mod
els-
-M
odel
TM
B 3
924-
8925
5.
AO
E-1
(U
.S.
fast
com
bat
supp
ort
ship
)I.
R
ound
y, W
.H.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
n--
Mod
el t
ests
8.
Pro
pell
ers-
-Des
ign-
-M
odel
tes
ts4.
P
rope
ller
mod
els-
-M
odel
TM
B 8
924-
8925
5.
AO
E-1
(U
.S.
fast
com
bat
supp
ort
ship
)I.
Rou
ndy,
W.H
.
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEY
-WA
TE
R A
ND
CA
VIT
AT
ION
PE
RFO
RM
AN
CE
O
F T
HE
PR
OP
EL
LE
R F
OR
AO
E-1
, by
W.H
. R
ound
y.
Oct
196
2.
iii,
14p.
il
lus.
, di
agrs
., gr
aphs
, ta
bles
, re
fs.
UN
CL
ASS
IFIE
D
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
per
form
ance
in u
nifo
rm i
nflo
w
of t
he p
rope
ller
des
igne
d fo
r A
OE
-1.
The
sere
sult
s ar
e sh
own
as i
ncep
tion
cur
ves
of f
ace,
bac
k, a
nd t
ipvo
rtex
cav
itat
ion
at e
ach
desi
gn r
adiu
s of
the
prop
elle
r.
Ope
n-w
ater
and
cav
itat
ion
char
acte
rist
ic
curv
es a
re a
lso i
nclu
ded.
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEF-
WA
TE
R A
ND
CA
VIT
AT
ION
PE
RFO
RM
AN
CE
O
F T
HE
PR
OP
EL
LE
R F
OR
AO
E-1
, by
W.H
. R
ound
y.
Oct
196
2.
iii,
14p.
il
lus.
, di
agrs
., gr
aphs
, ta
bles
, re
fs.
UN
CL
ASS
IFIE
D
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
per
form
ance
in u
nifo
rm i
nflo
w o
f th
e pr
opel
ler
desi
gned
for
AO
E-1
. T
hese
resu
lts
are
show
n as
inc
epti
on c
urve
s of
fac
e, b
ack,
and
tip
vort
ex c
avit
atio
n at
eac
h de
sign
rad
ius
of t
he p
rope
ller
. O
pen-
wat
er a
nd c
avit
atio
n ch
arac
teri
stic
cu
rves
are
als
o in
clud
ed.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
n--
Mod
el t
ests
3.
Pro
pell
ers-
-Des
ign-
-M
odel
tes
ts4.
P
rope
ller
mod
els-
-M
odel
TM
B 3
924-
8925
5.
AO
E-1
(U
.S.
fast
com
bat
supp
ort
ship
)I.
R
ound
y, W
.H.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
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Mod
el t
ests
3.
Pro
pell
ers-
-Des
ign-
-M
odel
tes
ts4.
P
rope
ller
mod
els-
-M
odel
TM
B 3
924-
3925
5.
AO
E-1
(U
.S.
fast
com
bat
supp
ort
ship
)I.
Rou
ndy,
W.H
.
I
--'-
---C
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEF-
WA
TE
R
AN
D C
AV
ITA
TIO
N P
ER
FOR
MA
NC
E O
F T
HE
PR
OP
EL
LE
R F
OR
AO
E-1
, by
W.H
. R
ound
y.
Oct
196
2.
iii,
14p.
il
lus.
, di
agrs
., gr
aphs
, ta
bles
, re
fs.
UN
CL
ASS
IFIE
D
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
pe
rfor
man
cein
uni
form
inf
low
of
the
prop
elle
r de
sign
ed f
or A
OE
-1.
The
sere
sult
s ar
e sh
own
as i
ncep
tion
cur
ves
of f
ace,
bac
k,
and
tip
vort
ex c
avit
atio
n at
eac
h de
sign
rad
ius
of t
he p
rope
ller
. O
pen-
wat
er a
nd c
avit
atio
n ch
arac
teri
stic
cu
rves
are
als
o in
clud
ed.
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEF-
WA
TE
R
AN
D C
AV
ITA
TIO
N P
ER
FOR
MA
NC
E
OF
TH
EP
RO
PE
LL
ER
FO
R A
OE
-1,
by W
.H.
Rou
ndy.
O
ct 1
962.
ii
i,14
p.
illu
s.,
diag
rs.,
grap
hs,
tabl
es,
refs
. U
NC
LA
SSIF
IED
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
pe
rfor
man
cein
uni
form
inf
low
of
the
prop
elle
r de
sign
ed f
or A
OE
-1.
The
sere
sult
s ar
e sh
own
as i
ncep
tion
cur
ves
of f
ace,
bac
k,
and
tip
vort
ex c
avit
atio
n at
eac
h de
sign
rad
ius
of t
he p
rope
ller
. O
pen-
wat
er a
nd c
avit
atio
n ch
arac
teri
stic
cur
ves
are
also
inc
lude
d.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
n--
Mod
el t
ests
3.
Pro
pell
ers-
-Des
ign-
-M
odel
tes
ts4.
P
rope
ller
mod
els-
-M
odel
TM
B 3
924-
8925
5.
AO
E-1
(U
.S.
fast
com
bat
supp
ort
ship
)I.
Rou
ndy,
W.H
.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-.P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
n--
Mod
el t
ests
3.
Pro
pel
lers
-Des
ign--
Mod
el t
ests
4.
Pro
pell
er m
odel
s--
Mod
el T
MB
892
4-89
255.
A
OE
-1 (
U.S
. fa
st c
omba
tsu
ppor
t sh
ip)
I.
Rou
ndy,
W.H
.
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEF-
WA
TE
R A
ND
CA
VIT
AT
ION
PE
RFO
RM
AN
CE
O
F T
HE
PR
OP
EL
LE
R
FOR
AO
E-1
, by
W.H
. R
ound
y.
Oct
196
2.
iii,
14p.
il
lus.
, di
agrs
., gr
aphs
, ta
bles
, re
fs.
UN
CL
ASS
IFIE
D
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
per
form
ance
in u
nifo
rm i
nflo
w o
f th
e pr
opel
ler
desi
gned
for
AO
E-1
. T
hese
resu
lts
are
show
n as
inc
epti
on c
urve
s of
fac
e, b
ack,
and
tip
vort
ex c
avit
atio
n at
eac
h de
sign
rad
ius
of t
he p
rope
ller
. O
pen-
wat
er a
nd c
avit
atio
n ch
arac
teri
stic
cu
rves
are
als
o i
nclu
ded.
Dav
id T
aylo
r M
odel
Bas
in.
Rep
ort
1670
.O
PEF-
WA
TE
R
AN
D C
AV
ITA
TIO
N P
ER
FOR
MA
NC
E
OF
TH
EP
RO
PE
LL
ER
FO
R A
OE
-1,
by W
.H.
Rou
ndy.
O
ct 1
962.
ii
i,14
p.
illu
s.,
diag
rs.,
grap
hs,
tabl
es,
refs
. U
NC
LA
SSIF
IED
Tes
t re
sult
s ar
e gi
ven
for
the
pred
icte
d ca
vita
tion
per
form
ance
in u
nifo
rm
infl
ow o
f th
e pr
opel
ler
desi
gned
for
AO
E-1
. T
hese
resu
lts
are
show
n as
inc
epti
on c
urve
s of
fac
e, b
ack,
and
ti
pvo
rtex
cav
itat
ion
at e
ach
desi
gn r
adiu
s of
the
prop
elle
r.
Ope
n-w
ater
and
cav
itat
ion
char
acte
rist
ic
curv
es a
re a
lso i
nclu
ded.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
n--
Mod
el t
ests
8.
Pro
pell
ers-
-Des
ign-
-M
odel
tes
ts4.
P
rope
ller
mod
els-
-M
odel
TM
B 3
924-
3925
5.
AO
E-1
(U
.S.
fast
com
bat
supp
ort
ship
)I.
R
ound
y, W
.H.
1.
Fas
t co
mba
t su
ppor
tsh
ips-
-Pro
puls
ion-
-P
redi
ctio
n2.
P
rope
ller
s--C
avit
atio
n--
Mod
el t
ests
3.
Pro
pell
ers-
-Des
ign-
-M
odel
tes
ts4.
P
rope
ller
mod
els-
-M
odel
TM
B 3
924-
8925
5.
AO
E-1
(U
.S.
fast
com
bat
supp
ort
ship
)I.
R
ound
y, W
.H.
I__
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