research memorandum/67531/metadc64421/m... · dual propeller are relatively independent of blade...
TRANSCRIPT
RM L50D21
RESEARCH MEMORANDUM
INVESTIGATION OF THE NACA 3-(3)(05) -05 EIGHT-BLADE
DUAL-ROTATING PROPELLER AT FORWARD MACH
NUMBERS T 0 0 . 9 2 5
By Rober t J. Platt, Jr. and Robert A. Shumaker
Langley Aeronautical Laboratory Langley A i r Force Base, Va.
i s + : . . h':; : d . ; r . i & , i . ' :,: ' c, 7 >if F:?&- , ;jr'
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
WASHINGTON June 19, 1950
NACA RM LWD21
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
RESEARCH MEMORANDUM
INVESTIGATION OF THE NACA 3-(3)(O?)-O? EIGHT-BLADE
DUAL-ROTATING PROPELW AT FORWARD MACH
NUMBERS TO 0.923
By Robert J . P l a t t , Jr. and Robert A . Shumaker
SUMMARY
Force tes t s were made on an NACA 3-( 3) ( 0 5 ) -05 e ight -b lade dua l - r o t a t i n g p r o p e l l e r i n t h e Langley 8- foot high-speed tunne l . The t e s t s covered a blade-angle range from 5 5 O t o 80° a t forward Mach numbers t o 0.925.
The r e s u l t s i n d i c a t e t h a t good e f f i c i e n c i e s can be obta ined a t high subsonic forward Mach numbers by opera t ion a t h igh b lade angles; a t a f r o n t - p r o p e l l e r blade-angle s e t t i n g of 75', t h e maximum e f f i c i e n c y was 87 percent a t a Mach n m b e r of 0.80, and 79 pe rcen t a t a Mach number of 0.85. L i t t l e or no e f f i c i e n c y ga in could be r e a l i z e d by increas ing t h e b lade angle beyond 73'.
INTRODUCTION
The NACA i s conducting a gene ra l i n v e s t i g a t i o n t o s tudy t h e e f f e c t s of compress ib i l i t y , des ign camber, b lade sweep, th ickness r a t i o , and dua l r o t a t i o n on p r o p e l l e r performance a t t r anson ic speeds. Resu l t s of t h e f i r s t t w o phases of t h i s i nves t iga t ion , dea l ing wi th t h e e f f e c t s of compress ib i l i t y and design camber on performance, were presented i n re ferences 1 and 2; b lade sweep, in re fe rences 3 and 4; and th ickness r a t i o , i n re ferences 5 and 6.
Seve ra l i n v e s t i g a t i o n s have been made t o s tudy t h e e f f e c t of d u a l r o t a t i o n on p r o p e l l e r performance, b u t a l l have been l i m i t e d t o low f o r - ward Mach numbers. Resu l t s of t hese i n v e s t i g a t i o n s show t h a t t h e maxi- mum e f f i c i e n c y of a dua l - ro t a t ing p r o p e l l e r i s g r e a t e r than t h a t of a comparable s i n g l e - r o t a t i n g p r o p e l l e r a t h igh values o f advance r a t i o ( r e fe rences 7 and 8 ) . much s m l l e r s l i p s t r eam r o t a t i o n losses of the dua l p r o p e l l e r .
This gain i n e f f i c i e n c y can be a t t r i b u t e d t o t h e
2 NACA RM L50D21
The r e s u l t s of r e fe rence 9 i n d i c a t e t h a t t h e induced l o s s e s of a dua l p r o p e l l e r a r e r e l a t i v e l y independent of b lade load d i s t r i b u t i o n . A dua l p r o p e l l e r t h e r e f o r e could be designed t o c a r r y , without loss of e f f i c i e n c y , a g r e a t e r load on t h e inboard s e c t i o n s and a smal le r load on t h e outboard s e c t i o n s than would be requi red f o r an optimum s i n g l e - r o t a t i n g p r o p e l l e r . Such a d u a l p r o p e l l e r , operated a t a h igh advance r a t i o , should be w e l l s u i t e d f o r opera t ion a t h igh subsonic forward Mach numbers, s ince bo th t h e lower r o t a t i o n a l speed and reduced outboard loading would tend t o de lay t h e compress ib i l i t y loss. A p r o p e l l e r of /
t h i s type has been designed and t e s t e d by t h e NACA i n t h e Langley 8- foot high-speed tunnel .
Presented he re in a r e t h e f o r c e - t e s t r e s u l t s for t h e NACA 3-( 3) ( 0 5 ) -05 e ight -b lade d u a l - r o t a t i n g p r o p e l l e r f o r b lade angles from 55' t o 80° a t forward Mach numbers t o 0.925. Only a l i m i t e d a n a l y s i s of t h e fo rce - t e s t r e s u l t s i s presented a t t h i s t i m e t o expedi te pub l i ca t ion of t h e b a s i c p r o p e l l e r r e s u l t s . Large-scale p l o t s of t h e b a s i c p r o p e l l e r char- a c t e r i s t i c s ( f i g s . 6 and 7) a r e a v a i l a b l e on r eques t t o t h e NACA.
b
c Z
C
2d
cP
C pF
R cP
SYMBOLS
b lade s e c t i o n chord, f e e t
s e c t i o n l i f t c o e f f i c i e n t
design l i f t c o e f f i c i e n t
t o t a l power c o e f f i c i e n t
f r o n t power coeff i c i e n t
r e a r power c o e f f i c i e n t
( Pn:3D5)
( pn:D5)
NACA RM LWD21 3
cT
D
h
J
M
n
P
R
T
T C
V
vO
( , c D 4 ) t o t a l t h r u s t c o e f f i c i e n t
p rope l l e r diameter, f e e t
maximum thickness of blade sec t ion , f e e t
(2) advance r a t i o
tunnel datum (forward) Mach number ( tunne l Mach number uncor- r ec t ed f o r tunnel-wall c o n s t r a i n t )
p rope l l e r r o t a t i o n a l speed, r p s
power absorbed by p rope l l e r , foot-pounds pe r second
(G) dynamic pressure, pounds pe r square f o o t
rad ius t o p rope l l e r t i p , f e e t
t h r u s t , pounds
(4 t h r u s t disc-loading c o e f f i c i e n t
tunnel-datum ve loc i ty ( tunne l ve loc i ty uncorrected f o r tunnel- wa l l c o n s t r a i n t ) , f e e t per second
equivalent f r e e - a i r ve loc i ty (tunnel-datum ve loc i ty cor rec ted f o r tunnel-wall c o n s t r a i n t ) , f e e t per second
4
B s e c t i o n b lade angle , degrees
NACA RM LPD21
s e c t i o n b lade angle ’0.75R a t 0.75 t i p r ad ius , degrees
‘1 e f f i c i e n c y (y) m a x i m u m e f f i c iency ‘ma,
P a i r dens i ty , slugs pe r cubic f o o t
Sub s c r i p t s :
F f r o n t p r o p e l l e r
R r e a r p r o p e l l e r
APPARATUS
T e s t equipment. - The p r o p e l l e r dynamometer descr ibed i n r e fe rence 1 was modified t o permit a dua l p r o p e l l e r t o be t e s t e d . These modifica- t i o n s cons i s t ed of t h e removal of t h e f l e x i b l e coupling between t h e d r i v e s h a f t s of t h e two dynamometer uni ts , t h e add i t ion of a thrust-measuring u n i t t o t h e f r o n t dynamometer, and t h e add i t ion of a tachometer t o permit t h e measurement of t h e r o t a t i o n a l speed of each p r o p e l l e r . A ske tch of t h e 800-horsepower p r o p e l l e r dynamometer, which was i n s t a l l e d i n t h e Langley 8- foot high-speed tunnel , i s shown i n f i g u r e 1.
The var iable-frequency power r equ i r ed t o d r i v e t h e f o u r dynamometer motors was obtained from a s i n g l e motor-generator s e t . Therefore , d i f - f e r ences i n loading between t h e f r o n t and r e a r p r o p e l l e r s , coupled wi th d i f f e r e n c e s i n t h e motor c h a r a c t e r i s t i c s , r e s u l t e d i n unequal r o t a t i o n a l speeds of t h e two p r o p e l l e r s . This d i f f e r e n c e i n r o t a t i o n a l speed amounted t o a maximum of 1.7 pe rcen t .
P r o p e l l e r . - The 3-foot-diameter dua l - ro t a t ing p r o p e l l e r cons i s t ed of e i g h t b lades : f o u r i n t h e f r o n t p r o p e l l e r and f o u r of oppos i te hand i n t h e r e a r p r o p e l l e r . t h e p r o p e l l e r diameter was used. c e n t e r l i n e s was 6 inches.
A l a r g e sp inner wi th a diameter 36 percent of The d i s t ance between t h e p r o p e l l e r
The f r o n t and r e a r b l ades d i f f e r e d s l i g h t l y i n t w i s t , as shown by t h e blade-form curves of f i g u r e 2 . In o t h e r r e s p e c t s t h e design of t h e
NACA RM L50D21
f r o n t and r e a r b lades w a s ident ica l . . NACA 16 - se r i e s a i r f o i l s ec t ions were used throughout. A photograph of a b lade is shown i n f i g u r e 3. The o f f s e t of t h e b lade a t t h e roo t was intended t o counterac t t h e torque-force bending moment a t t h e high b lade angle f o r which t h e pro- p e l l e r w a s designed.
The p r o p e l l e r was designed f o r an advance r a t i o of 7.13 and a t o t a l power c o e f f i c i e n t of 6.48. The t i p Mach number a t such a high advance r a t i o was only about 9 percent g r e a t e r than t h e forward Mach number. The design b lade angle of t h e p r o p e l l e r w a s approximately 77'.
The b lade loading f o r which t h e e ight -b lade dua l p r o p e l l e r w a s designed i s shown i n f igure 4. A l s o shown f o r comparison i s t h e mini- mum induced-energy-loss loading of an e ight -b lade s i n g l e - r o t a t i n g pro- p e l l e r a t t h e same advance r a t i o of 7.15. It is ev ident t h a t t he d u a l p r o p e l l e r was designed t o c a r r y more load on t h e inboard b lade sec t ions and less load outboard than would be c a r r i e d by a s i n g l e - r o t a t i n g pro- p e l l e r of minimum induced energy l o s s .
TESTS
Each run was made a t a f i x e d value of t unne l Mach number and b lade- angle s e t t i n g , with the r o t a t i o n a l speed var ied t o cover a range of advance r a t i o . The d i f f e rence i n b lade angle between t h e f r o n t and r e a r p r o p e l l e r s w a s chosen t o produce approximately equal power absorpt ion a t
6
Forward M a d nmber , M
NACA RM L 3 0 D 2 1
53
.60 ~-
~ - -
peak eff ic iency. The range of blade angle and Mach number covered is given in t h e following tab le :
65 63.3 70 68.2 75 73 80 772
0*35 .
- - I
65
70
85
90
?F' 'R
55 53.7
55 53.7
55 53.7
55 53.7
Blade angle a t 0 . 7 y ( d e d
I 1
60 58.5
60 58.5
60 58.5 60 60
60 58.5
60 58.;
60 58.5 60 60
65 63.31.70 68.2173 73 I - - ---- 65 63.3 70 68.2 75 73 80 7 7 2
REDUCTION OF DATA
Propel le r t h r u s t . - The determination of the separate t h r u s t s of f r o n t and r e a r propel le rs would have required the measurement of the pressure e x i s t i n g between the frmt and r e a r spinners a t each operating condition. pickups proved unsuccessful; therefore , only the over -a l l t h r u s t could be determined. Propel le r t h r u s t as used herein i s defined as the sum
An attempt t o measure t h i s pressure with e l e c t r i c a l pressure
NACA RM L P D 2 1 7
of t h e two a x i a l s h a f t f o r c e s produced by t h e sp inne r - to - t ip po r t ion of t h e b lades . T h e method used t o determine t h r u s t t a r e s and evalua te t h e p r o p e l l e r t h r u s t i s similar t o t h a t used f o r a s i n g l e - r o t a t i n g p r o p e l l e r a s descr ibed i n r e fe rence 1.
P r o p e l l e r torque.- The ind ica t ed torques of t h e f r o n t and rear pro- p e l l e r s were co r rec t ed f o r sp inner t a r e s . and dependent only on r o t a t i o n a l speed.
These c o r r e c t i o n s were small
Tunnel-wall co r rec t ion . - The d a t a (except f o r Mach number) have been co r rec t ed f o r t h e e f f e c t of tunnel -wal l c o n s t r a i n t on v e l o c i t y a t t h e p r o p e l l e r t e s t plane by t h e theory of r e fe rence 10. r e c t i o n i s shown i n f i g u r e 5. A few experimental checks of t h i s cor -
This v e l o c i t y cor -
r e c t i o n were made by t h e method of r e fe rence 1; good agreement was obtained.
RESULTS AND DISCUSSION
The o v e r - a l l p r o p e l l e r c h a r a c t e r i s t i c s a r e presented i n f i g u r e 6 f o r each t e s t value of tunnel-datum Mach number. f i c i e n t CT and t o t a l power c o e f f i c i e n t C p a r e based on t h e f r o n t - p r o p e l l e r r o t a t i o n a l speed. p l o t t e d a g a i n s t t h e advance r a t i o of t h e f r o n t p r o p e l l e r . of t h e f r o n t - p r o p e l l e r t i p Mach number with i t s advance r a t i o i s included i n t h e f i g u r e . A s used he re in , t h e tunnel-datum Mach number M i s n o t co r rec t ed f o r tunnel -wal l c o n s t r a i n t . The f r e e - a i r Mach number, however, can be obtained by applying t h e v e l o c i t y co r rec t ion , presented i n f i g - ure 5 , t o t h e tunnel-datum Mach number. The c o r r e c t i o n w i l l be a m a x i - mum a t a tunnel-datum Mach number of 0.925, a b lade angle of 6 5 O , and an advance r a t i o of 3.85. number i s 1.2 percent and t h e f r e e - a i r Mach number becomes 0.914.
The t o t a l t h r u s t coef-
These c o e f f i c i e n t s and t h e e f f i c i e n c y are The v a r i a t i o n
A t t h i s p o i n t , t h e c o r r e c t i o n t o t h e Mach
The ind iv idua l power c o e f f i c i e n t s of t h e d u a l p r o p e l l e r a r e shown i n f i g u r e 7. The f r o n t - p r o p e l l e r power c o e f f i c i e n t C i s based on
t h e f r o n t - p r o p e l l e r r o t a t i o n a l speed nF and p l o t t e d a g a i n s t t h e f r o n t -
p r o p e l l e r advance r a t i o JF. The r e a r - p r o p e l l e r power c o e f f i c i e n t is
pF
shown i n two forms: C i s based on nR and p l o t t e d aga ins t JR; pR
% and p l o t t e d a g a i n s t . The r e l a t i o n JF whereas C t i s based on pR
8 NACA RM L50D21
between t h e t o t a l power c o e f f i c i e n t presented i n f i g u r e 6 and t h e ind i - v idua l power c o e f f i c i e n t s presented i n f i g u r e 7 i s
cp = cpF + CPRl The e f f e c t of forward Mach number on t h e maximum e f f i c i e n c y of t h e
d u a l p r o p e l l e r i s shown i n f i g u r e 8 f o r s e v e r a l b lade angles . Mach numbers t h e maximum e f f i c i e n c y i s about 90 percent for f r o n t - p r o p e l l e r blade-angle s e t t i n g s from 65' t o 7 5 O . e f f i c i e n c y of about 85 percent a t t h e h ighes t t e s t b lade angle of 80° i s probably t h e r e s u l t of an unfavorable geometry of t h e f o r c e vec to r s , which tends t o magnify t h e e f f e c t of p r o f i l e drag.
A t low
The r e l a t i v e l y low
A s has been shown previous ly f o r s i n g l e - r o t a t i n g p r o p e l l e r s , increas ing t h e b lade angle delays t o h igher Mach numbers t h e e f f i c i e n c y loss due t o compress ib i l i t y e f f e c t s . The r e s u l t s show, however, t h a t l i t t l e or no e f f i c i e n c y ga in can be r e a l i z e d by inc reas ing t h e f r o n t - p r o p e l l e r blade-angle s e t t i n g beyond 75'. angle s e t t i n g of 7 5 O , which i s very nea r t h e design angle , t h e maximum e f f i c i e n c y i s 87 percent a t a Mach number of 0.80 and 79 percent a t a Mach number of 0.85. angle e n t a i l s , however, a reduct ion i n t h e power which can be absorbed. This , of course, i s a r e s u l t of t h e low r o t a t i o n a l speed of t h e p r o p e l l e r .
For a f r o n t p r o p e l l e r b lade-
Operation of a p r o p e l l e r a t such a h igh b lade
The maximum e f f i c i ency i s p l o t t e d i n f i g u r e 9 aga ins t t h e f r o n t - p r o p e l l e r advance r a t i o JF Good e f f i c i e n c i e s a r e obta ined a t h igh va lues of advance r a t i o up t o forward Mach numbers as h igh a s 0.85. A t t h e h ighes t t e s t Mach numbers of 0.90 and 0.925, t h e d a t a i n d i c a t e t h a t opera t ion a t lower values of ad-vance r a t i o i s necessary f o r b e s t e f f i c i e n c y . This e f f e c t i s s i m i l a r t o t h a t p rev ious ly found f o r s i n g l e - r o t a t i n g p r o p e l l e r s .
for each t e s t value of forward Mach number.
The e f f e c t of small changes i n t h e r e a r - p r o p e l l e r b lade angle on t h e dua l -p rope l l e r c h a r a c t e r i s t i c s i s shown i n f i g u r e 10 f o r a f r o n t b lade angle of 75'. A t a Mach number of 0.70 t h e r e i s no measurable change i n f r o n t - p r o p e l l e r power c o e f f i c i e n t f o r t h e range of r e a r - p r o p e l l e r b lade angles inves t iga t ed . number of 0.90, t h e r e a r p r o p e l l e r does inf luence t h e f r o n t - p r o p e l l e r power absorp t ion ; a decrease i n t h e r e a r - p r o p e l l e r b lade angle causes a s l i g h t increase i n t h e f r o n t - p r o p e l l e r power c o e f f i c i e n t .
However, a t t h e s u p e r c r i t i c a l Mach
More l imi t ed d a t a of a s i m i l a r type a r e shown i n f i g u r e 11 f o r a f r o n t - p r o p e l l e r b lade angle of 60'. l i t t l e in f luence on t h e f r o n t - p r o p e l l e r power c o e f f i c i e n t a t a Mach number of 0.70. i t s e f f e c t i s pronounced.
The r e a r p r o p e l l e r appears t o have
However, a t t h e high s u p e r c r i t i c a l Mach number of 0.83,
9 MACA RM LwD21
The d i f fe rences i n maximum ove r -a l l e f f i c i ency a t t he various r e a r - p rope l l e r blade-angle s e t t i n g s , shown i n f i g u r e s 10 and 11, a r e be l ieved t o be within t h e experimental accuracy.
CONCLUSIONS
Force- tes t r e s u l t s f o r t he NACA 3-( 3) ( 0 5 ) -05 eight-blade dua l pro- p e l l e r a t Mach numbers t o 0.925 ind ica ted the following conclusions:
1. Good e f f i c i e n c i e s were obtained a t high subsonic forward Mach numbers by operation a t high blade angles; a t a f ron t -p rope l l e r blade- angle s e t t i n g of 7 5 O , t he maximum e f f i c i ency was 87 percent a t a Mach number of 0.80 and 79 percent a t a Mach n m b e r of 0.85.
2. L i t t l e o r no e f f i c i ency gain could be r ea l i zed by increasing the blade angle beyond 75'.
Langley Aeronautical Laboratory National Advisory Committee f o r Aeronautics
Langley A i r Force Base, V a .
10
REFERENCES
NACA RM L5OD21
1. Delano, James B . , and Camel , Melvin M . : Inves t iga t ion of t h e NACA 4-(5) (08)-03 Two-Blade Propel le r a t Forward Mach Numbers t o 0.925. NACA RM L ~ G O & , 1949
2. Delano, James B . , and Morgan, Francis G . , Jr.: Inves t iga t ion of t he NACA 4- (3) (08) -03 Two-Blade Propel le r a t Forward Mach Numbers t o 0.925. NACA E(M ~9106, 1949.
3. Delano, James B . , and Harrison, Daniel E . : I nves t iga t ion o f t h e NACA 4- (4) (06) -04 Two-Blade Propel le r a t Forward Mach Numbers t o 0.925. NACA RM L9107, 1949.
4. Delano, James B . , and Harrison, Daniel E . : I nves t iga t ion of t h e NACA 4 - (4 ) (06)-057-45A and NACA 4 - ( 4 ) (06) -057-45B Two-Blade Swept P rope l l e r s a t Forward Mach Numbers t o 0.925. NACA RM L9L05, 1950.
5. Delano, James B . , and Camnel, Melvin M . : Inves t iga t ion o f NACA 4-(0)(03)-045 and NACA 4-(0)(08)-045 Two-Blsde Propel le rs a t Forward Mach Numbers t o 0.925. NACA RM L9L06a, 1950.
6. Carmel, Melvin M . , and M i l i l l o , Joseph R . : I nves t iga t ion of t h e NACA 4-(0) (03) -045 Two-Blade Propel le r a t Forward Mach Numbers t o 0.925. NACA RM L5OA3la, 1950.
7. Biermann, David, and Hartman, Edwin P . : Wind-Tunnel Tes ts of Four- and Six-Blade Single- and Dual-Rotating Tractor Propel le rs . NACA Rep. 747, 1942.
8. Lesley, E . P . : Tandem A i r P rope l le rs - 11. NACA TN 822, 1941.
9. Gilman, Jean, Jr.: Wind-Tunnel Tes ts and Analysis o f Two lO-Foot-. Dicmeter Six-Blade Dual-Rotating Tractor P rope l l e r s Di f fe r ing i n P i t ch Di s t r ibu t ion . NACA TN 1634, 1948.
10. Young, A. D . : Note on the Application of t h e Linear Per turba t ion Theory t o Determine t h e Effec t of Compressibil i ty on Wind Tunnel Constraint on a Propel le r . RAE TN No. Aero. 1539, Nov. 1944. (Also ava i l ab le as R . & M. No. 2113, B r i t i s h A.R.C., 1944.)
Tunnel w a l l r
Figure 1.- Test apparatus.
.o
'5
. w
0
. Q'
2.02 s g *% i s 0
86
82
78
74
70
66
Blade staz%~7, v/R Figure 2.- Blade-form curves for NACA 3-(3) (O5)-O5 dual propeller.
'
NACA RM L5OD21
Figure 3 - Photograph o f NACA 3- (3) ( 0 5 ) -05 p r o p e l l e r blade.
/13
L O
.8
I
b Cr
.6
*4
2
0 ,2 .3 -4 0 '
5 / a d e
I I
t
Figure 4.- Comparison of design blade-loading of NACA 3-(3)(0>)-05 dua l propeller with blade-loading of optimum single-rotating propeller.
0 U iu
bQG6
,992
8988
I 7 Y
Fi&e 3. - Tunnel-wall-interference correction for 3-foot-diameter propeller in Langley 8-foot high-speed tunnel.
.
1.4
I .3
1.2
I . I
1.0
.9
I- O. .8 c C
0 .- .- 'c .7 0
c
.6 1 I-
.5
.4
14
13
12
I I
10
9
a * 8
7 Q)
0
L
$ 6 a"
5
4
- - I
0
1.5 LL
5 i
. t
1.0 2 $
.5 3 5 n
O F
I .oo
.75 F s
.50 :G c
w-
5 .25
0 0 2 4 6 8 10 12 14 16 18
Advance ratio, JF
(a) M = 0.35.
Figure 6.- Characteristics of NACA 3-(3)(05)-05 eight-blade dual-rotating propeller.
8 Iv P
1.4
I .3
12
I. I
1.0
.9
I- 0 - .8 c c Q)
0 .- .- + .7 0
c cn
r 2 .6 I-
.5
.4
.3
.2
.I
0
14
13
12
I I
10
9
8
7
6
5
4
3
2
I
0 0 2 4
1.5 ,,- 5 c
L
1.0 2 G
.5 3 Zi CL
O F
1.00
.75 F >;
50 14 c
'c
5 .25
0 6 8 10 12 14 16 18
Advance ratio, JF
(b) M = 0.53.
Figure 6.- Continued.
(
I .4
1.3
I .2
1 . 1
I .o
.9
I- 0
* .8 c c W
0 .- .- ‘c
.7 s 2 .6 4-
r t-
.5
.4
.3
.2
. I
0
14
13
12
I I
10
9
8
7
6
5
4
3
2
I
n
1.5 LL
I 4-
L
1.0 x $
.5 3 *
z CL
O F
1.00
75 1 s
.50 :4 0 c Q)
rc
;5 .25
0 = 0 2 4 6 8 10 12 14 16 18
Advance ratio, JF
( c ) M = 0.60.
Figure 6.- Continued.
!5 Ln 0 U Iu P
I .4
1.3
I .2
1 . 1
I .o
.9
.8
.7
.6
.5
.4
.3
.2
.I
0
a 0
L 0) 3 a
14
13
12
I I
10
9
8
7
6
5
4
3
2
I
0 0 2 4 6 . 8 10 12 14 16 18
Advance ratio, JF
Iv 0
1.5 LL
z c
.5 3 z n
O F
1.00
.75 1 2;
50 14 E Q,
LL-
5 .25
r
( d ) M = 0.65.
Figure 6. - Continued.
0
.
,
1.4
1.3
1.2
1 . 1 I I
1.0 10
.9 9
+ a 2 . 8 0 . 8 t 0)
0
c + t
0 .- .- .- .-
*-
- , . 7 % 7 0 0
.5 5
.4
.3
.2
_ I
8
4
0 2 4 6 8 10 12 14 16 18 Advance ratio, JF
( e ) M = 0.70.
Figure 6.- Continued.
*<Loo = N (J)
'O!lDi a3UDApv
81 91 PI 01 8 9 P Z 0 1 W
I
2
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9
L
8
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Z'
€.
P.
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2 9' 2
L' % p. 3
8' &
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I .I
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a
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ust
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nt,
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-
-
-
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bb
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is
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io
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-
iu
ic
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Pow
er c
oeffi
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p
z II 0
a3 0 .
I .4
1.3
! .2
1 . 1
1.0
14
13
12
I I
10
I- 0
w- a, 0
c In
-c 2
I-
9 9
a 0
u 0
1.5
4 8 I0 12 14 16 18 2 Advance ratio, JF
(h) M = 0.85.
Figure 6.- Continued.
1.4
1.3
1.2
1 . 1
I .o
.9
.8
.7
.6
.5
.4
.3
.2
.I
0
a 0 c c a, .- Y- Lc
W
0 L W 3 a"
14
13
12
I I
10
9
8
7
6
5
4
3
2
I
0 0 2 4 6 8 10 12 14 16 18
Advance ratio, JF
(i) M = 0.90.
Figure 6.- Continued.
1.5 LL
z i
c
1.0 2
.5 3
Oi=
5 r" n
I .8D
.75 F s V c
.50:: rc
;5 .25
'0
t? Ln 0 U Tu t-
I .4
1.3
1.2
1 . 1
I .o
.9
I- 0, .8 + c 0)
0 .- .- z .7 0
4- 2 .6 I- r
.5
.4
.3
.2
.I
0
14
13
12
I 1
10
9
< 8 + c 0 .- 5 7
$ 6 2
0
L
5
4
3
2
I
0
( 3 ) M = 0.925.
Figure 6. - Concluded.
F u1 0
7
6
5
4
3
2
I
0
ratio based on nF Power coefficient and advance
0 2 4 6 8 10 12 14 16 18 Advance ratios, JF and JR
(a) M = 0.35.
Figure 7. - Individual power coefficient curves of NACA 3-( 3)(03)-05 eight-blade dual-rotating propeller.
H
b 0 U
2 4 6 8 I 0 12 14 Advance ratios, Jp and dR
P
7
6
5
2
0 tj rc
7
6
5
4
3
2
I
0 0 2 6 10
Advance ratios, JF and JR
( d ) M = 0.65.
Figure 7.- Continued.
12 14 16
W 0
7
6
5 of a 0 '13
0
$4 LL a 0
Advance ratios, JF and JR
(e) M = 0.70.
Figure ' . - Continued.
t? ul ,o U Iu I-J
7
6
5 c1c n
0 -0
0
E4 0.
LL n 0 ui + (u
0
0)
0
0)
.- E 3
L
3 2
2
I
0 C
Adww fa&%+ and JR - -
( f ) M = 0.7'1:.
Figure 7.- Continued.
W Tu
t+ ul 0 U m t-l
I
7
6
5 ar a
0 Q
0
ar a
a 0.
LL
0
4
3
H tn 0 U
b t
0
2
I
I
0
Advance ratios, JF and JR
(g) M = o.~o. Figure 7.- Continued,
7
6
5
Power coefficient and ratio based on nF
____- Power coetficient and ratio based on n a
. . . . . . --, .. -. .. -. . . . . . . . . . .
. . , .
. , I . - . . .
LL a 0 vi c C
0
Q)
0
.- E 3
2
I
0 0 2 4 '0 12 14 16 18
Advance ratios. JF and JR
(h) M = 0.85. H L ' ul 0
P 8 Figure 7.- Continued,
Advance rot'=, + and- JR
(i) M = 0.90.
Figure 7.- Continued.
- - _
F
Q
,
e C J
P Lf +- I .
_I_---.
1
Figure 9.- Variation of maximum efficiency with advance r a t i o f o r NACA 3- (3) (05) -05 eight-blade dual propeller
/
Advunce ruth,
(a) Individual power c o e f f i c i e n t s
Figure 10.- E f f e c t o f s m d l variations i n rear b lade angle f o r a f r o n t b lade angle o f 75'.
. /
3
, JF
(b) Over-all propeller characteristics.
F i v e 10.- Concluded.
58.5
Advance rat io, JF.
(a) Individual power coef f ic ien ts
Figure 11.- Effect of small variat ions in r e a r blade angle for a front blade angle of 60’.
W
32 33 3 4 J5 36 37 38 357 40 41 42 43 32 3 3 J# J5 3'6 37 38 3 40 -
Advance rat io, JF
(b) Over-all propel ler characteristics.
Figure 11.- Concluded.
U
Mach Number Ef fec t s - Propel le rs 1.5.2.5
Inves t iga t ion of t h e NACA 3 - ( 3 ) ( 0 5 ) - 0 3 Eight-Blade Dual-Rotating Propel le r a t Forward Mach Numbers t o 0.925.
By Robert J. P l a t t , Jr. and Robert A . Shumaker
NACA RM ~ 5 0 ~ 2 1 June 1950
P l a t t , Robert J., Jr., and Shumaker, Robert A.
Inves t iga t ion of t he NACA 3 - ( 3 ) ( 0 5 ) - 0 3 Eight-Blade Dual-Rotating Propel le r a t Forward Mach Numbers t o 0.925.
By Robert J. P l a t t , Jr. and Robert A. Shumaker
NACA RM L3OD21 June 1950
Propel le rs , Dual Rotation 1.3.2.7
Inves t iga t ion of t he NACA 3-(3) (03)-0> Eight-Blade Dual-Rotating Propel le r at Forward Mach Numbers t o 0.925.
By Robert J. P l a t t , Jr. and Robert A. Shumaker
NACA RM ~ 5 0 ~ 2 1 June 1950
Abstract
I
Force-test r e s u l t s are presented f o r t he NACA 3-( 3) ( O 5 ) - O 5 eight-blade dual propel le r , which was designed f o r a blade angle of a p p r o x h a t e l y 75'. The t e s t : covered a blade-angle range from 55' t o 80° a t Mach number: t o 0.925. Some da ta on t h e e f f e c t of small changes i n the rear -propel le r blade angle a r e included. Good e f f i c i enc ie s were obtained a t high subsonic Mach numbers by operation at high blade angles.
Ab s t ra'et
Force-test r e s u l t s a r e presented f o r the NACA 3-( 3)(05)-03 eight-blade dual propel le r , which w a s designed f o r a blade angle of approximate1 75'. The t e s t s covered a blade-angle range from 55' t o 80 a t Mach numbers t o 0.925. Some da ta on the e f f e c t of small changes i n the rear-prope.ller blade angle a r e included. Good e f f i c i e n c i e s were o b t a h e d a t high subsonic Mach numbers by operation a t high blade angles.
B
Abstract
Force- tes t r e s u l t s a r e presented f o r t he NACA 3-(3) (05) -05 eight-blade dual propel le r , which w a s designed f o r a blade angle of approximate1;Y 75'. The t e s t s covered a blade-angle range from 55' t o 80 a t Mach numbers t o 0.925. Some da ta on t h e e f f e c t of small changes i n t he rear -propel le r blade angle a r e included. Good e f f i c i e n c i e s were obtained a t high subsonic Mach numbers by operation a t high blade angles.
NACA RM ~ 5 0 ~ 2 1