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

€

P

S

9

L

8

6

01

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21

€I

PI

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I'

Z'

€.

P.

G.

2 9' 2

L' % p. 3

8' &

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I .I

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ust

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p

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I .4

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1.0

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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