v . Auburn University Libraries
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File D 52.43/130
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'-- 3 1706 025 85130 9
MATERIEL DIVISION REPORT, SERIAL No. 2783
PUBLISHED BY THE CHIEF OF THE AIR CORPS. WASHINGTON, D. C.
Vol. VI September 15, 1927 No. 595
COMPARISON OF FLIGHT TESTS OF A NUMBER OF
WOOD PROPELLERS WITH WIND TUNNEL TESTS
ON A SERIES OF WOOD PROPELLER MODELS
(AIRPLANE BRANCH REPORT )
Prepared by Frank W. Caldwell
Materiel Division, Air Corps
Wright Field, Dayton, Ohio
April 16. 1927
UNITED Sf A TFS
GOVERNMENT PRINTING OFFICE
WASHINGTON
1928
Ralph Brown oraugho
LIBRARY
MAY 2 8 Z013
Non·Depoitorv
Auburn University
I
'
CERTIFICATE: By direction of the Secretary of War the matter contained
herein is published as administrative information and is required for the proper
transaction of the public business.
(II)
COMPARISON OF FLIGHT TESTS OF A NUMBER OF WOOD
PROPELLERS WITH WIND TUNNEL TESTS ON A SERIES
OF WOOD PROPELLER MODELS
The engineering division constructed a series of
30 model wood propellers of a uniform planform and
had wind tunnel tests made on these models at Leland
Stanford University. The power coefficients for this
series of models is shown in graphic form in Propeller
Research Report No. 8, McCook Field Serial No. 2226,
pages 11 and 12.
It was desired to find whether any consistent relation
could be established between the power coefficient
of a large number of wood propellers designed at the
engineering division and tested in flight and the power
coefficients of the model propellers.
For this purpo e a representative station for the
full-size propellers was taken at 0.75 times the tip
radius and the angle of attack, ratio of Vi/V at the
tip and the power coefficient P 0 was computed for
the full-size propeller. The power absorbed by the
propeller had to be obtained from the engine power
curve.
The power coefficient obtained in this way was then
compared with the power coefficient for a model having
the same ratio of V1/V and the same angle of
attack. The ratio of these two values of P 0 was
adopted as a scale coefficient.
All of the model propellers were designed with an
aspect ratio of 6. Where the aspect ratio of the full size
propeller was other than 6 the power coefficient
was corrected in proportion to the aspect ratio so as
to reduce the value to an aspect ratio of 6.
When the camber ratio of the full-size propeller was
different from the camber ratio of the model, the actual
angle of attack was increased to an angle having the
same lift coefficient as the standard camber ratios.
Propeller No ________ _________ _ 037643
Engine ________________________ Wright E-2
Airplane ___ -------____________ TW-5
Plane speed (m. p. b.)__________ l15
Propeller (r.p.m.) ___ __________ 1, 720
Planform______________________ 1
34923
Wright E-2
TW-5
ll4
1, 755
1
7.03
The empirical assumption is frequently made that
the power coefficient per blade for the four-bladed
propellers is 0.95 times the power coefficient per blade
for the identical two-bladed propellers at the same
value of Vi/V and angle of attack. The scale factor
for four-bladed propellers was therefore corrected by
dividing by 0.95.
The scale factor is shown plotted against the value
of Vi/V and also against the angle of attack at the
representative ~tation .
In general the scale factor seems to decrea e somewhat
with increase of Vi/V and with increase of angle
of attack, though the results arc not sufficiently consistent
to establish thi trend.
o consistent relation between the scale factor and
the size of the body behind the propeller could be
established.
There are a number of probable causes for the inconsistency
of these results; the most important is
probably the unequal tor~ional deflection of the propeller
blades due to inequahties in the material and
due to variations in torsional stresses. There is
probably a very considerable error due to assumptions
as to the engine horsepower. A third very important
cause of discrepancy is the instrumental and observational
error in flight-test data which were taken at
random over a considerable period of time.
It would probably be poss.ible to obtain more consistent
results from tests of the metal propellers designed
at the engineering divi ion on account of the homogeneity
of the aluminum alloy and on account of t he
greater consistency of the torsional stresses in the type
of design being used for aluminum-alloy propellers.
X-48407
Liberty 12, G'd 5:3
LWF-T-3
104.18
1, 117
3
6
X--49702
Liberty 12, G'd 3:2
Dll-4-B
II
1, 166
3
6
X--49558
Liberty 12, G'd 2:1
DH-4-B
121. 3
918
3
6
X-52385
Curtiss D-12
PW-8
Aspect ratio___________________ 6. 96
Increase in camber_ ___________ - --- - -------- - Minim um camber --- ----- --- ---- - -- -- ------------ -- ------ ---------- ----------
1-c. g,
7
353
increased . 01
Engine (b.b.p.)_______________ 172 175 448 440 448
Propeller diameter (feet)_______ 8. 5 8. 5 14 12 13. 83
Blade anglo at 0.75 radius____ __ 17. 5 16. 2 13. 5 17. 2 21. 0
V1/V=V1/r nD________________ . 22 . 2138 .1863 . 2360 . 2672
Vt/0.75.,,. nD------------------ . 2935 . 285 . 2485 . 3145 . 3562
q, at0.75 radius________________ 16. 336° 15. 917° 13. 950° 17. 450° 19. 600°
Angle of attack (Bla-q,)_______ +L 114° +o. 283° - . 45° -. 25° 1. 40°
0.984 1.043
Increase in angle due to camber_ ------- -- - ---- ------------------------ -------------------- -------------------- --------------------
Actual P 0 per blBde___________ .0380 .0363 .0307 .0555 .0575
P • per blade from model tests__ . 0225 . 0200 . 0156 . 0205 . 0285
Correction for aspect ratio_____ . 0194 . 0171 -------------------- ----------- ---- --- -- --- --------------- --
Po actual
Scale factor P. modei---------- . 980 1. 062 1. 352
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Propeller o _____________ _ X-49408 X-49963 X-54025 X-52312 X-47328 X-19740
Engine ____________________ Liberty 12, G'd 2:L ... Liberty 12, G'd 5:3 ____ Liberty 12, G'd 5:3 ____ Packard 2,500, G'd Sidney Sidney
2:1. Jaguar. Jaguar.
Airplane___________________ LWF-T-3 Douglas C-1 Douglas C-1 XLB-1 DH-4-B DR-4-B
Plane speed (m. p. h.l---- - 108. 3 122 122 124. 5 109. 7 lll. 9
Propeller (r.p.m.) ________ --------------- --------- -------------------- ------------- - ------ ---------------------- ----------------------------- -
Planform ___ __________ _____ 3 3 3 c. g. 3 3 3
Aspect ratio__ _____________ 6 6 6 6 6 5. 535
Increase in camber_ ___ _____ -- ---------------------------------------------------------------------'--------------------------------------------
Engine (b. h. p.)__________ 450 448 410 830 350 348
Propeller diameter (feet)___ 15 13. 666 13. 333 15. 5 JO. 33 9. 5
Blade angle at 0.75 radius__ 15° 15° 19. 75° 17° 15. 8° 17. 5°
V1/V=Y1/.,,nD_____________ .2125 .2235 .2595 .2225 .1943 .2166
Vi/0.75 .-nD ____ ----------- . 2838 . 298 . 346 . 297 . 2592 . 289
1> at 0.75 radius_----------- 15. 85 16. 60 19.10 16. 55 14. 53 16. 13
Angle of attack (Bla-<f>) __ -0.85 -1.40 +o. 65 +o. 45 +i.267 +i.367
Increase in a due to cam- ber_ ______ _______________________________________ -- ____________ --- ___ -- __________ _________ ___ ________ ----- _____ _______ _____ --- --- -- ___ ---- __ Actual Pc per blade_______ .0348 .0386 .052 .0455 .042 .0632
Pc per blade from model
tests_____________________ .0165 .0152 .025 .0212 .0203 .0228
Correction for aspect ratio_ ----------- ------------ - ------------------------ ______ ------ ------------ -- ------------ __ ------ ------------ . 0247
Pc actual
ScalefactorP,model·----- 1.054 1.27 1.04 1.072 1.034 1.28
Propeller No._---------------------------------- -- X-47269 X-43153 X-43003 I (4 blades)
X-43429
(4 blades)
X-47331
Eugine·---- ------------------- --- -------------- --- Liberty 12 Wright H-3 L. C. W-1-A Wright Radial Lawrance J-1
Dayton Wright
PS-1
no
Airplane----------------- -- ----------------------- - LWF-T-3 R-3 Verville GA-2 I PA-1
Plane speed (m. p. h.)_ ---- -- ----- - ---------------- 94. 6
PPlraoupfeollremr _(_r_. _p_._ _m__.)_._ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- -----------__- -_-_ _- -_-_ 1, 6501
Aspect ratio.-------------- ---- ----------- -- ------- 7
Increase in camber __ ------------ ---- -------------- 353
Engine (b. b. p.l------------------------------- --- 423
Propeller diameter (feetl--------------------------- 10. 5
Blade angle at 0.75 radius______ ___ _________________ 12
V 1/V = V1/rnD ___ ------ ----- - ------ ---------------- . 1527
Vi/0.75 .. nn_______________________________________ . 2035
<f> at 0.75 radius------------------------------------ ll. 50°
Angle of attack (Bla-<f>)------- ------------------- +o. 50
Increase in a due to camber________________________ • 0374
Actual P, per blade--- -- -------------------------- . 0374
Pc per blade from model tests_________________ __ ___ . 0145
Correction for aspect ratio _________________________ --------------
P, actual
Scale factor Pc model _________ ------------------__ 1. 29
191
2, 100
1
7
353
381
8
23. 3
. 3175
. 423
22. 93°
+o. 367
1.167
.0633
.034
. 0292
1.088
Propeller No--------- --- - ------------- X-4i743 (4 blades) X-47465
104. 5
1, 610
3
6
7. 7
765
ll. 5
12. 5
.158
. 2105
ll. 88°
+o. 617
. 257
. 0453
. 0158
1. 432
X-482ll
I
I
Engine.----------------------------- -- Liberty 12 Liberty 12 inverted Liberty 12 inverted
Des. for Loening.
Airplane ... ---------------------------- L\\"F- T-3 Amp. test on DH-4 Loening COA-1
Plane speed (m. p. h.)_ ___ _____________ 98. 7 105 117. 7
Propeller (r. p. m.l---- --- ------------- 1, 795 I, 760 I, 780
Planform _____ _________ ____ _________ ___ 3 3 3
Aspect ratio___________________________ 6 5 6
Increase in camber ____________________ -------------- ------------ ---- - - ---- -- --------------- ---- -----
Engine (b. h. p.l------ -- --------------• 440 435 440
~l~~l~~g1~aa'fg~~ ~~~i~s:::::::::::::: i 1g: ~0 180167 200167
V,/V = V1/ irnD .. --------------------- -' .1464 . 204 . 226
\'1/0.75,.. nD ___________________________ , .1952 . 272 . 3012
1> at0.75 radius_ __________ _____________ 11. 05° 15. 216° 16. 766°
Angle of attack (Bl a-<f>l-------------- -1. 25° +2. 784° +3. 234°
Increase in a due to camber. ____ ______ ------- --------- ----- ·----------------------------------------
124
1, 615
3
6
7. 7
362. 6
8.167
22. 2
.263
.3506
19. 32°
+2. 0
. 257
.0600
.0342
0.877
37593
Liberty 12
DH-4
125
1,680
3
7.045
253
41
9. 833
16. 7°
. 2115
.282
15. 75°
+o. 95°
1. 783
1, 960
3
5.4
222.6
6. 75
18.4
. 2322
.310
17. 23°
+1.167
. 0522
. 024
.0266
1.0300
X-47269
Liberty 12
Douglas C-1
115. 8
1, 790
3
6
445
10. 5
12°
.1722
. 2296
12. 933°
-0. 933°
X-42985
Packard 2025
VCP-R-1
186
1, 960
1
7
353
580
9. 167
22
. 2892
. 3855
21. ogo
+0.92
1.167
.0600
. 0332
. 02466
o. 9035
X-47269
Liberty 12
NBS-4
101. 2
1, 705
3
6
Minimum
camber.
424
10. 5
IL 7°
.1584
. 2112
11. 967°
-0. 267°
Actual Pc per blade_ __________________ . 0302 . 0542 . 054 .046 . 0309 . 0343
P, per blade from model tests__________ . 0105 . 0255 . 0295
Correction fw. a;gt-;:
1
ratio.----------- -,- ----------___ . 0306 ---- -- -- - -------- __ -- -- -
Scale factor P, modei------------------ 1. 438 . 932 . 963
. 0232
. 0187
1. 273
. 0135 . 0137
1. 145 1. 25
5
Propeller No ___ ___ ----------------------------- -- -------- X-47269 X-47269 X-47ir,9 X-47269 047315
Engine- ------ -------·----------------------------- --- - ---- Liberty 12 Liberty 12 Liberty 12 Liberty 12 Liberty 12 Liberty 12
Airplane_________________________________ __ ________ ________ DH-4 DH-4 DJI-4 DH-4 DH-4 NBS-4
Plane speed (m. p. h.)------------------------------------- 79. 2 92 JOO. 5 117. 6 112. 25 99. 4
Propeller (r.p.m.)- -- -- - ------------------- --------------- I, 650 1, 700 1, 730 l , 800 l, 800 1, 680
Plan(orm_____ _____ ___________________________ _____________ 3 3 a 3 3 3
Aspect ratio-------------------------------------------- --- 6 6 6 6 6 6
Increase in camber-------------------------------------------------------------------------------------------------------------------·---------
Engine (b. h. P->--------- --------------------------------- 4ll 422. 5 429 440 440 418
Propeller diameter (!eet)----------------------------- -- ---- 10. 5 10. 5 JO. 5 10. 5 JO. 5 JO. 33
Blade angle at 0.75 radius.. __ ---------------------- --- ------ 11. 7 11. 7 JJ. 7 11. 7 11. 7 !3. 6
V1{V =V1/..- nD -------------------------------------------- . 1279 . 1440 . 1550 . 173 .1 661 .16()()
Vi/0.75,.. nD----------------------------- ' ----------------- .1704 . 1920 . 2065 . 2316 . 2215 . 2133
4> at 0.75 radius---·----------------------------------·---- - · 9. 66° 10. 86° 11. 66° 13.16° 12. 50° 12. 33°
Angle of attack (Rla-<J>l--- -- ------------------ ----------- +2.034 +.834 +.034 -1.466 -.800 1.267
Increase in a due to camber ____ ____ ______________________ ----------------------------------------- ------ ------ --- ----------------------------
Aetna! Pa per blade_. - ------------------------------------ . 0362 . 0345 . 0328 . 0300 . 0300 . 0372
P • per blade from model test -------------------------- ____ . 0145 . 0144 . 0140 . 0127 . 0125 . 0166
Correction for aspect ratio- ----- ------------------------------------------- ----- ----------------------------------------------------- -------- --
p, actual
Scale factor Pa modei---------- ---------------------------- 1. 249 1.194 1.171 1.181 J. 200 1.120
P ropeller r o ___________ ---- - - - - -- -- - - -- - -- - -- - - - - - _ -- _____ _ 047315 047315 047315 037643 X-44923 X-43799
Engine--------- ---- --- -------- -- -------------------------- Liberty 12 Liberty 12 Liberty 12 Wright E Wright R-1 Wright E
Airplane---------------------- ----------------- ---- -------- DH-4 XA-1 DJI-4 VE-9 DH-4 VE-9
~~~~~1~~;(~. ~~nP.i ~L: :::::::::::::::::::: :::::: :::::::: 1, ~~- 35
1. m· 2
1, ~!b· 4
1. ii~· 6
1. ~- 2
2, ~ Planform________ __________ __________________ ______ __ ______ 3 3 3 l 3 1
Aspect ratio_______ _______ _______ __ ___ ____ __ _______________ 6 6 6 6. 9 6 7
Increase in camber ·------- ------ --- -- - -- ---------- ------- - ------------------------------------------------- ------- - -------------·-------------
Engine (b. h. P-l------ ----- -------------- --------------- - -- 427 424 430 434 418 209
Propeller diameter (!eet)----------------------------------- JO. 33 JO. 33 JO. 33 8.1; J0.16 7. 83
Blade angle at 0.75 radius __ ___ ---------------------------- 13. 6 13. 6 13. 6 17. 3 14. 5 17
Vi/V = Vif,.-nD •. ------------- ---- --- ----------- ------- ----- . l 5 .1928 . 1732 . 222 .187 . 214
Vi/0.75,.-nD- -------- ------------------------------ - ---- --- - . 2466 . 257 . 231 . 29fi . 249 . 285
.pat 0.75 radius.------- ------ --- --- - ----------------------- 13. 85° 14. 416° 13.166° 16. 50° 14° 15. 934°
Angle of attack (Bla-<J>l---------- - ------------------------ -0. 25° -0. 816° +o. 434° +o. 800° +o. 50° +J. 066°
Increase in a due to camber _______________________________ ---------- --- --------------- ---- ---- -- ----------------------------------------------
Actual P. per blade____ ____ ______________ ____ ____ ______ ____ . 0363 . 0368 . 0360 . 0880 . 0408 . 035
Pc per blade Crom model tests____________ __________________ . 016 . 0151 . 0175 . 0220 . 0182 . 021
Correction for aspect ratio.-------------------------------- ---------- ---- __ ------------ ------ -------- . 0193 ---------· --- - . 01 7
P, actual
Scale !actor P, model·------------------------------- ----- - 1.135 1. 22 1. 00 1.14 1.12 1.162
Propeller No_--------------------------------------------- X-52983 070899 070899 070899 X-45827 (4 blades)
X-47465
Engine---------------------------------- ------------ - --- -- Wright E Wright E Wright E Wright E Liberty 12 Liberty 12
Airplane.--------------------- ----------------------------- PT-! P '.r-1 PT-1 PT-1 DH-4 DII-4
Plane speed (m. p. h.l---------- -- ------------------------- 99. 4 102 104. 2 101. 6 119. 37 117. 7
Propeller (r. p . m.l---------------------------------------- 1, 920 1, 920 2, 100 1, 850 1, 760 l, 480
Planform__________ ________________ ______ __________________ l 1-c. g. 1-c. g. I 1 3
.Aspect ratio----------------------------- --- --------------- 7 6. 05 6. 05 6 7 5
Increase in camber·--------------- -------- -- ---------------------- - -------------------- --------------------------- - 353 --------------
Eugine (b. h . P->------------------------------------------ 202 210 218 197 434 368
Propeller diameter (fcetl- ---------------- -- --------------- 8. 333 8. 666 8. 666 9. 0 10 8.166
Blade angle at 0.75 radius •• -------------------------------- 14 13. 5 11. 5 13. 2 14 18. 25
V1/V=V1/"nD--------------------------------------------- .1736 .1712 .1602 .1708 .190 . 2513
V1/0.75rnD------------------------------ ------ ------------ . 2315 . 2282 . 2140 . 2275 . 2535 . 3350
.pat 0.75 radius.------------------------------------------- 13. 033° 12. 85° 12. 083° 12. 816 14. 233 18. 516
Angle or attack (Bla-<J>l---------------------------------- o. 967 o. 650 -o. 583 +o. 384 -0. 233 -0. 266
Increase in a due to camber_ ___________________________ ____ ---------------------------------------------------- --------- ----- --- ------------ ---
Actual P, per blade--------------------------------------- . 036 . 0302 . 024 .1)26 . 0395 . 0605
p, per blade from model tests______________________________ • 0175 . 0165 . 0132 . 0162 . 0162 . 0220
Correction for aspect ratio.--------------- --- -------------- . 0150 . 0164. . 0131 -------------- . 0139 . 0264.
P. actual
Scale factor P •model-------------------------------------- 1. 20 • 9225 .916 .803 1. 412 1. 204
Propeller No ---- ---- --------------------------------------
(4 Blades)
X-47465
6
(4 Blades)
X-48211 X-52385 X-24705 X-24705
Engine----- -------- --- ------------------------------------ Liberty 12 Liberty 12 Curtiss D-12 Wright 300 Wright 300 Wright 300
Airplane----- ---- --- ---------- -------------------- - - ------- COA-1 COA-1 PW-9 XBI-A XBI-A XBI-A
Plane speed (m. p. h.l-------------------------------------- 118. 91 121. 2 133. 8 126 72 122
Planform___________ _____ ____ _______ _______________________ 3 3 1 3 3 1
Aspect ratio __ __ _________ :__ _______________________________ 5 6 7 6. 06 6. 06 7. 2
Increase in cambe'----- --- ----------------- -- ----- -- ------- --------- - ---- --- - - - - - ------ 35% 7. 7% 7. 7% 25%
Engine (h. h. p.l -- ------ --------- -- -- ------------- -- ------ - 4.32 422 430 359 320 359
Propeller diameter (feetl---- - --- --------------------------- 8.166 8. 166 8. 666 8. 666 8. 666 9
Blade angle at 0.75 radius_________________________________ _ 18. 25° 10. 80° 15. 20° 17. 40° 17. 40° 15. 60°
V1/V=V1/,,. nD-------------------------------------------- . 2322 . 2443 . 180 . 2148 . 1328 . 1806
:~n~; r~~ius--==:::::::::::::::::::::::::::::::::::::::::: 17: ~0 rs: l:0 13: ~2 16°
2865 ld~0 ld~g~
Angle of attack (Bla-1>) ---- - - ------- - - -------- --- ---- -- -- + 1. 017 + 1. 734 + 1. 70 + 1. 40 +6. 234 +2. 067
Increase in a due to camber _______________ _________________ ------- -------------- -- -------------------------------------------------------------
Actual p, per blade----- ------- ------- ------------------- - .0545 . 0586 . 0319 . 0540 . 0600 • 0440
P, per blade from model tests______________________________ . 024 . 027 . 0225 . 0231 . 0228 . 0230
Correction for aspect ratio_--------- ---- ----- - - ------------ . 0288 . 0286 . 0193 . 0228 . 0227 . 0192
Scale factor ~: :'~~:\ ---- - ------------ -- ------------------ . 944 1.142 . 8265 1. 180 1. 321 1.148
Propeller No __ ___ _______ -- -- ------------- - ------- -- X-23501
Engine. __ - - - - -- -- --- - - --- -- --- -- -- - -- _: ___ - -- - - -- --
~J~~~a~;eed (iii~ ii.- ii~i::::::: :: : :: ::: : : : : : : : : : : : : : : :
Planform. ----- - --- - - ---·- -- -- ----- ----- - ---- - - - - -- - -
Aspect ratio.--------------------------------------_
Increase in camber_ ___ ----- - -----------------------
Engine (b. h. p.) __ • --------- ---- ------------------PBrlaodpeel
alenrg dleia amt e0t.7e5r r(afedeituls- --_-_-_-_-_-__-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_- -_
V1/V = V 1/,..nD ___ --- ______ ----- -- -- ------- ---- ------
: '~~· l.~5~~dius: :: : : : : : : : : : : : : : : : : : : : : :: : : : : : : : : : : : :
Angle of attack (Bla-1>l----------------------------
Wright 300
XBl-.A.
68
1
7.2
25%
332
9
15. 6
. 1216
.162
9. 20°
X-24705
P ackard 1237
PWl-A
134
3
6.06
7. 73
356
8.666
17. 4
- 230
X-24705
Packard 1237
PWl-.A.
88
3
6. 06
7.7%
317
X-19925
Wright 300
DH-4
115
1
6. 96
357
9.166
15. 7
.1868
.249
13. 983°
1. 717°
X-47511
Curtiss D-12
PW-9
160
1
7
35%
412
8. 166
19.6
. 2502
.334
18. 466°
1.134°
X-47511
Curtiss D-12
PW-9
163
1
7
35%
448
8.166
19. 6
.2492
.332
18. 366°
1. 234°
Increase in a due to camber _________ __ ____________ _
Actual P, per blade--------------------------------
6.40°
. 833
- 0521
. 0215
. 0172
. 3065
17. 033° o. 367°
- 2565
- 0535
8. 666
17.4
.1688
- 225
12. 683°
4. 717°
- 2565
- 0665 --------_-04i5- ----------_-ij545· ----------:0547
p , per blade from model tests ________ __ ____________ _ .0222
. 0219
. 0255
. 0252
- 0203 - 026 - 026
Correction for aspect ratiO ------------ - ------------- - 0175 . 0223 - 0223
Scale factor ~: ::~ ------------------------------ 1.455 1. 219 1. 320 1. 188 1. 220 1. 225
Propeller NO--------- -- __ ----- --- __ --------_ --- --_ --- --- --- ------- ___ _ X-47511 37593 37593 37593
Engine.---------------------------- - --- - -------- ------- --------------- Curtis D-12 Liberty 12 Liberty 12 Liberty 12
Airplane--------------------------------- -- -------- -- --------- -------- PW-8 DH-4 DH-4 DH-4
PPllaannfeo srpme e_d__ (_m__._ _p :._h_._l_-_-_-_-_-_-_-_-_-_-_-_-_-_--_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-__- 161l 109. 32 118. 63 121. 63
Aspect ratio· ------- - -- - ----- --- ---- -- - -- --------- ------ --- ------------ 7 7. 045 7. 045 7. 045
Increase in camber---------------------------- -------- ---------------- 35% 25% 25% 25%
Engine (h. b. P-l------- - ------------------ ---------------- ----- - ----- - 447 405 412 414
Propeller diameter (feet)------------------ -- ---- ------------ --- - ------ 8.166 9. 833 9. 833 9. 833
Blade angle at 0. 75 ra dius __ - ------------- - --- - -------------- -- --- ----- 19. 6° 16. 6° 16. 6° 16. 6°
V1/V=V1/,,nD --------- ---------------- ---- - ------------------ ---- ---- . 2495 .192 . 2045 . 2082
Vi/0.75 ,,-nn ___ --- - ------------ ------- ------ ----------------- - ----- --- - . 3326 . 256 . 273 . 278
1> at O 75 radius ______ _____ ________ --- - ------ ------------ -- -- --- - -- ___ 18. 40° 14. 366° 14. 966° 15. 533°
Angle of attack (Bla-1>)------ --- --- ------ - - -- ------------- ---------- +1. 20° +2. 234 + L 634 + 1. 067
Increase Ill a due to camber_ __ ______________________ ·- ------------------------------------- ---------------------------- ----- ----
Actual P, per blade---- - ----------- ------------------------------ -- --- . 0562 . 0512 . 0495 . 0485
p, per blade from model tests-- - ----------- --------------------- ------ . 026 . 0225 . 0221 . 0215
Correction for aspect ratio ___ _____ ___________ ·------------- --- - ---- --- . 0223 . 0192 . 0189 . 0183
P, actu al
Scale factor p, model·--------------- ---------------------------- ------ 1. 26 1. 335 1. 312 1. 320
0
X-53359
Curtiss D-12
PW-9
142
c. g.
7
35%
428
8. 75
16. 2°
.193
- 2575
14.433°
1. 767
1. 167
. 0316
. 0246
. 0211
1. 498
Air Service Information Circulars
