REPORT No. 375

FULL-SCALE TESTS OF METAL PROPELLERS AT HIGH TIP SPEEDS

BY DONALD H. ‘WOOD

SUMMARY

Thi8 repori dew-ihe8 te8t8of 10julkale metal propeller8 of seixral thicknew ratio8 at oarious tip speeds up

to IJ60 feet per 8econd. ITie testg were made in the

Propeller Research Tunnel of the National ~dui80ry

Committeefor Aeronuutic8 at Langley Field, ‘Virginia..

% results indicate no 10S8of ej%ieny up to tip 8peed8

of approxirnate~y1,000 feet per 8econd. ~boc~ thi8 tip

~peed the loiMI%at a rate of abotd 10 per cent per 100

feet per 8econd increase relative io the ej’ioi+mcyat the

lower 8peed8for propeller8 of pitch diumeter ratios 0.S

to 0~. Propellers huving sectim of small thickne8s

ratio can be run at 8@htly higher speeds than thick ones

before beginning to lo8e ej’kienoy.

INTRODUCTION

As a result of extensive researohj the design of aircraft propellers can be cmried out now with satisfactory accuracy in most instances. There yet remain

some phases of the problem, such as the design of

propellem to operate at high tip speeds, for which available data are contradictory.

The forces acting on a body moving uniformly in a

fluid depend mainly on the size, shape, and orientation

of the body; its speed; the properti= of the fluid; and

in some cases the value of the earth’s attraction. By

means of the “Theory of Dimensions” given in standard textboob (Reference 7), it is shown that the force

on a body varies m

where

p= density of the fluid,

V=veIooity of the body relative to the fluid,

L=any characteristic length of the body,

v= coefficient of kinematic viscosity,

c =velocity of sound in the fluid,

g-acceleration due to gravity,

f =function.

The fit part onIy of the above expression (pV L’)

is given definitely by dimensional theory and was formerly used in expressing the law of variation of the

rai+ance of bodies. The force is also a function of a

number of nondimensiomd expressions, three of which

The tit of time ~-,

are given in the brackets. P

commonIy known as Reynokls number, is now known

.-

.—

to be of great importance, part.i&darlyin passing from

model to full scale. The second Q

()

~ is mainly of

importance whare the body is mowing near the free

surface of the fluid. It would apply in the case of

boats, since wavw might be produced. In aerodynmoica this function maybe negjectedj since the bodies

move in the interior of the fluid. The functions

()

p W L2 and ~ contain the ~portant variables

p, P, L, 1? in most probkms in aeronautics. In

propeIIm, however, where the blade tips may operate

at speeds near or above the velocity of sound, the third

(9 term vzithin the bracket ~ becomes of importance.

As the velocity of the propeller tip approaches the

speed of sound, the density of the fluid in the vicinity

of the body is appreciably changed. We therefore

speak of the effeot of this function as the ‘{ compressib$ty eflect.“ C1earlythe separation of the functions

is mere~yfor convenience of discussion; in fact-,W the

vtiables operate simultaneously in a ghren case.

When the propeller tip speeds approaoh the velooity

of sound as t+ey do with modern directdxhe, highpowered engines, the theory of propeller action is SW

incomplete, and test redta are so dependent on scaIe

that the designer is on less fim ground. Mmy model

teats made for the Br@h Aeronautical Researoh

Committee are reported in Reference 1. A few tests

reported in Reference 6 were made with a fdkcale

propelIer up to tip speeds of 900 feet per second. It is

apparent from an examination of all the9e test results

that the model propelkrs have, throughout the range

of the tests, krger losses in efR&ncy at high tip speeds

than the fulkcale propellers. The rewdb of a number

of tests of airfoiIsat high speeds reported in References

2, 3, 4, and 5 indicate that the loss of tiectivenew of

-.

propellers at high speeds is due to the ohange in airfoiI

characteristic.s. The fact that the results of some of “‘—

the recent model tests made at higher values of Reynohla hTumber than the tit tests, and the fulkoale

tats, also at high valu= of ReymoMs Number, indicate

les loss of &imcy, leads to the occlusion that the “ - _

Reynolds Number is interrelated with the “ compressibility effect” in such a way that the “compressibility tiect” is IS at higher Reynolds Numbem than

at low.

237
238 REPORT NATIONAL ADVIBORY

Because of this interrelation and also in view of the

wsll-lmown discrepancies between model and full-scale

propeller tests, particularly the efleot of the different

deflections, it seemed advisable to secure some directly

applicable resulti from tests of full-size propellers.

Many full-scale tests have been made in the PropeUer

Research Tunnel of the National Adtioly Committee

for Aeronautics, and the results have been reported as

they became avaiIable. The present tests relating

directly to the tip-speed problem are a continuation of

this work. Ten propellers were tested at tip speeds

from 500 to 1,360 feet per second. Of the 10, 4 were

of standard plan form and thickness and the other 6

COMMItiEE I’OR” AERONAUTICS

I

was accomplished by circulating water from a large

tank on the floor below, instead of using a radiator.

The fuselage as arranged for testing is showu in _

Figure 1.

The 10 propellers used in this investigation inchdcd

two series of three propellers each. They wero 9 feet

6 inches in diameter and were designed to havo a

constant thickness ratio over a major por~ion of the

blade. .Theseratios were 0.06,0.08, and 0.10. In one

series the section was the standard modifiod R. A.I?.-6

propeller section, and in the other the Clark Y section

were of standard form, but were of d.Merent thick- ]

‘ formed by making all ordinates in the same ratio to

the maximum ordinate as they are in the Clark Y

airfoil. In addition four standard propellere were

.

nesses and sections, three thickness b each of two

sections. The results of over 160 tests made on these

propellers are here reported.

APPARATUSAND METHODS

The Propeller Research Tunnel with its At equipment and methods has been described in Reference 8.

The regular ted-fuselage and torque dynamometer

were used in these tests, The standard metal fuselage

framework containing the torque dynamometer wassurrcmnded by a fabric-covwed wood fuselage simulating that of an airplane, A Curtiss D–12, 435-hors+

power engine was mounted on the forward plate. The

whole was supported on the reguIarbalance with water

and gas connections carried up from the floor. CooIing

tested. Two had narrow tips and two, wide tips. One

of each was 9 feet in diameter and the other one,

geometrically similar, was 9 feet 6 inches in diameter.

For ca.weniencej thase propellers are designated

R-6, R-8, R-10; C--6, G-8, C-10; S-TV-9.5, S-N-9.5,

S-W-9, and S-N-9, the letter C meaning Clark Y and

R meaning R.A.F.-6 modified. The numbers 6, 8,

and 10 represent the thicknw ratios 0.06, 0.08, and

0.10. S, W, and N signify standard, wide, and

narrow, respectively. The numbers 9.5 and 9 are the

diameters.

Tliereference tiible correlates these designations with

the drawing numbers, which may be familiar to some

readers. The diameter, section, and thickness ratio

are * given.
FULL-SCALE TESTS Ol? METKL PROPELLERS AT HIGH TIP SPIJFiOS 239

REFERENCE TABLE Figure 2 is a drawing of propeller C-6 and is typicgl

of the six special propellers, since they ace all of the

same pkm form. Figure 3 shows the stmdard widetip propeHer (S-W+I.5) and Figure 4 the standard

narrow-tip propeller (S–N-9.5). The blade width,

thickness, and pitch diameter ratios are gim.u in the

nondimensiomd curves of F~ES 5 md 6. From these

curvm and the section ordinates given in F~ge 7, any

of the propeIIerblades can be laid out.

—

—

,

I Figm4.

~

0:10.

O.m. Om.

O.1o.

?-4

vargiug.

Veryhlg. Vllrylng.

5

:.:.. -

Y

F.

—.

6ModF. 6Mod--

F. 6Mod_ -+

G&----------- ~ Qft.-dh

c-a--.--- ak-ofn.

c-lo . ...-.-—-- =9 ~ft.-6fn.

R-a... 21% Oft.+k g&.-.____ 2124 eft.-l3f.n.

...-.— 2123 ‘a[L-6 in.

CIerk

Clark

Chrk

B.A.

B.A.

B.A.

.-

.—

S-W-9.5-.—.—— 4

9[L-afm

a-N46.._ % 9IL-6fn. S-W—9— S-N–9—__— ]% :E!k

R .L

R.&

R. A.

R. A. .-

,:.- —

Ftfchk fiqwed wifhWe mgfe of 9.8-at42”sfafbn

FIQUIU!l-Ropetler C-6

ORDINATES OF SECTIONS AT VARIOUS EADII FOR METAL PROPELLEE BLADE.

.-

-.

.-

9.6 feet&meter,rkht-knd (@.2)

L I 4s”r 84” r

24,, ~ I

! 10”, m-r. m“ r

s

,upper Lowar T

L.4wer UrJper Lmfer

Inch Inch Inek

&’a 0.15 O.M

.I?a .23 .0s

.06 .20 X)J

.C!a .42

.m .= .m .C1 .U .m .CI .50 .m .W .4 .m

.m .40 .W :% :%

.m .al .W .12 .(UI

I

Low’et Upw JInek

an

.16

.22

.29

.86

.W

.M

-as .29 .2a .M.C3

- mier

7-Inche8 Inch

0. . ..- . . ..—-.— 0.00 o-m

2.6 . . . . ----------- .~ .!a

5.............—- .E4 .44

10........-....–. l.ls .59

‘20-------------- 1.4

do.-._—------- Lsa ::

40---------------- L% .78

60---------------- L Bl .70

do................ LS8 ::

?u..-..----------- lJJ

w.......... .._- .42

w ...... ........ .. .54 .%

II&C;7 IB@8

am .14 .51

.n .70

AJ i~ .36 L19

.ati L16

.33 M&

.ao

.26 .75 .!31 .12 :=

IUCA aa6 .M-10 .04

.m

.m.al

.m.al .W.W.Cm

Iti

R29

.41

.83

.75

.92

.95

.Q3

:%

.ml

.42

.23

rick meh

km a22 .12 .81

.m .43

.Ca .s6

.m .70

.m .72

.m .n

.m .&l

.m .m .00 .G

.= :% I .17

Inch Id

au am

:; r ::

.m .2J

.al , .32

.m; ..m .al, .Z

.m .23 .W .19

.m .19

.m .K

Inch

O.ca

.04

.02

%

.m

.m

.m

.m.00

.m.W

InCk

am

.09

.12

.la

.m.Za

.m.19 .16

.13

.Cc

.05

Inck

am . .

.%.01

.m.fnl .W

.m.W.W

.m

.m

hchea

O.Ii

.60

i!!

L29

L413

L46

L39

L27

LM

.=

.51

. —-

.—.

+’, -.

Rd. L. E........ .72

Rad.TEE.. . ...- .2L

Cfhmd------- 6-20

I

. u .15 !

.12 , .L7J I

.m .04

.16 .01 .OI i

.01 .-OT .OL .O1

.Ofi

.OI

a.49 —-

.— ---

.

a standard design practice md has some advanttge in

reducing propeller-body interference.

.-—

The six propellers of the series were tested at their ...

designed pitch (9.6° at 0.75E) and the thinnest one in

each series was tdso tested at 6.8° at 0.75R. The 9-

foot diameter standard propellers were tested at 10°

at 0.75R and the 9-foot 6-inch diameter propellers at

6.8° at 0.75R. These low pitches were necessmy to

secure I@h tip speeds with the engine power and tunnel .—

air speed available.

We note that the designed pitch of the six special

propellers is practictiy constant with radius, except for

a slight washout toward the hub. When the blade

setting is changed, the pitch diameter ratio is no longer

ccmtant with radius and the pitch distribution is as

shown. The standard propellers have newly a constant pitch when set for a ~ of 0.5 at 0.75R. At the

settings used there is a washout of pitch toward the tip

as vd as toward the hub. Thii variation of pitch is
240 REPORT NATIONAIJ ADYtSORY COMMITTE E FOR AERONAUTICS

In these tests, the engine revolutions per minute were

held conetant throughout the entire range of sir speeds.

Separate tats ware made at invervsls of 200 r. p. m.

from 1,000 to 2,000, and at intervals of 100 r. p. m.

from 2,oOOto the highest speed that could be obtained,

2,700 r. p. m. in one or two cases.

Simultaneous readings were taken of the thrust,

torque, air speed, revolutions per minute, and deflection

at the 42-inch radius. Six yawheads pkwed behind

the propeller were connected to a photographicallyrecording multiple manometer, which took reoords at

the same time. The data obtained from this instmment are being used to compute the airfod characteristics of the propeller sections. This information will

be issued in a later report. Separate tests wore made

to determine the drag of the fuselage and supports

with the propeller removed.

FKQUBB&—PropeIlerS-W-O.5

ORDINATES OF SEOTIONS AT VARIOUS RADII FOR METAL PROPELLER BLADE

9.5ft. diameter,rfght-hmrd(SS.3)

I w r 12”r

w’ r

upper

Upw Lam Um Lower

hwhm Ii& ImLhg Ip4 Iir&c

2.5.......-. __---- .--. _.___– a62

L------------------------------------ .44

-_..j i!! .M .80 :21 .70

30-.-...-.------..—.. L lb 4J

.- . . . . . . . ..--..--... _.._..-—__...-..-./ yJ ~g ;6J .M #

3...: . . . . . . . . . . . . ..-. --. .. ———-— .-—---

40

M .---------------------------—-––-------1 . . ..-. .- . . . ..-.. ------------------------------- k: f $; :E ;:

W.- . . . . . . . ..-... —---.-— ----------------- L=

m........- ... ... --------------------------- -1 L 17 LW :E :F3

w ....-...-.- ....-. -_.-.-.. -_-.. -__---.—. .s9 :; AJ .67

W_ ......__... —_.. -_.—. —.__...-._..._.. i .66 .23 :%’ .42

-----------------------------W-I Find.L. E.._. ..-_. ._._. ._.-_ -------

Rad. T. E..

Chord.._.. _.--- ....._.. .---_ ..__.

N,, ~

UPW

Inch

aaa .M.76

.m

.95

.94

.90

.Sa

.70

:~

.10

.U?

!Jy, ~ 30”r 4P r

Upw upper upper

hch Iuch Inch

:: am CL20

.m ~~

.n

:ti .46

:: .63

.62 :;

:E .00

.67 .m .42

.47

:Z :%

..37 :X .17

‘It .00 .03

:% .0s .04

1 I I

7.60 7.Ed 7.06 &m

J?”

W r

up*

Inch

0.14

.al

.27

.X2

.84

.34

.82

.20

:%

.12

:%

-iii

64”r

Upfw

Inch

a 02

.a9

.11

.16

.1s

.19

.19

.18

;~;

.11

.01

.Oi

-iz

The ohordfs dfvldd Into IOM@ parts or statfom, VrIththeone at the kadlng O@ snhdfvldedfnto helwa and quarters. S WUSIS

stationsfn psr writ of ohord,fromthe lmd!’mgsdge+

The horizontal form which is read on the balance

may be either a thryst or a drag. This force R may

be considered as made up of the three horizontal

components:

T= the thrust of the propder while operating in

front of the body (the tension in the crank

shaft) .

D= the dra of the body alone (without propeller7 at the same dynamic pressure.

AD= the change in drag of the body due to the

action of the propeller slip stream.

so that

R= T–D–AD, (1)

—

To obtain the propu~lve efficiency, which includes

the propeIIer-body interference, an effective thrust is

used which is defined as

Effective thrust = T– Ul,

or from (1) =Z?+D.

-.

The power was ocsmputeddireotly from the measured

torque and revolutions per minute. An accurately

calibrated tachometer W& used and the engine was

eritirely enclosed by cowling, so that no corrections for

the aIip stream torque reaction on the engine were

necessary.
FULL-SCALJJ TESTS OF NETAL PROPEIIIZWIS AT ~GH TIP SPEEDS Ml

RESULTS The above coeflkients were first plotted against the

coefbient ~~ and a fair curve drawn through the The results are given in _ 8 to 33, inclusive,

and in Table 1. The measured values me reduced to

the usual coefficients of thrust, power, and propulsive

efficiency.

effective thrust

c,= ~n=D4

c.=

input power

p nSDE

effectivethrust X velocity of advance q=

input power

where

~= propelIer diameter

and

n= revolutions per unit time

points. A typical set of such plots is given in Figures

8 to 16, inclusive. Ths are fairly representative of

al the tests and indicate the scatt.e~m of the twt

points, which & one measure of the accuracy of the

testing. The torsional deflections computed from the

tunnel measurements are also plotted on these figures.

AU the deflections were uniformly emalI, averaging

about -i-%0, although there were some higher vahms

y

at low values of ~~. These small deflections are in

:.—

contrast to those found in earlierpropeller tests, which

gave much higher deilectione. Most of this is acThese coefficients are nondimensional and any counted for by the low pitch of these propellers.

homogeneous system of units maybe used.

FIWJ’EB4.-PropeIferS-N-9A

ORD~ATES OF SECTIONS AT VARIOU8 RAJJJl FOE =TAL =OpELLER3~ES

9.6fsetcfismetar,rkht-frsnd0%3.4

.-

Is- r

1

24” r

Upper Upper

Inck LA

0: g au

.46

.n .eo

.92 .72

.m

% .75

.92

.s4 ::

.%

:ti .43

.64 .2-I

—_

.Io .m

.07 .06

SW r

upper

Inrh

o. m

.s7

.50

.60

.66

.62

.60

.53

.47 .s6

.22

.M

.05

-

W r

Jmr

Inch

0.21

:%

.4s

.61

.50

.4s

.44

.s

.Za

.18

.(E.

.CFi

7.M

c

4Wr ‘64”r L

Uppsr ppsr

Iurh ‘ Imrh

0.11 O.G’

.16 .10

.!21i .IS

.m .111

.~ I .17

.~ I .17 .% t .16

.16

:% .M

.15

.09 ::

t

-+ ::

Femrr

Inrh

IL16

.22

..30

.M

.38

::

.36

::

.16

.IM

.W

-Gi

s

1 I

Uplm IOJliWupper LQTiel

IncLhc4; Inc&; Imiw

===4 ~: ,; ::

+A. . . . . . . . . . . ..-. --—. ---.——

& . . . ____________

lo.-...-–-— ——

! L

m–-_...__-_--—_--—_——— I.xl 1.87

m.........-—--—-.–-–-——— LZ3 L46 L44

do...........-. ..- .. _______ L73 14S L48

m..-.-..---.-.-—————— L6d ! LB L87

m....-.. --.--- .. ....--––-—-—--

m.–-- .... ..-_. -—---..-. -..-___– i% Lo?’

81.____ —_-—--—--

W.........-—..— -----1 ::

, :: ,:;

Inc,b

:2J

.6a

.64

.67

.06

.64

:i$

..28

.2a

—

_—.-

ESKLL. E....-..-.--.-.–-–-.—-–——’ La

Itad. T. E.-- ....-. --.-. -.--— ------------- I I

::

Chord------- ——

‘: I ‘m

!I%e chordk divfdsd into 10sqnafmrfriorStStf~~~ me ~ atm _ edeod~d~ ~toh~= ~d q~t~. s @I@

Stationsinpsrcemtof chordfr omlesdfwdaw.

‘“d‘“m 7.67

The faired curves of C’~, CP, and q were retraced given in Figures 19 to 30, hcltive. The close sp~i%

with the curves for all revroIutionspeeds for any one of these curves may lead to comhaion, but comparisons

propeller on the same sheet. The (.% and (7Pcurves between them’ are made on supplementary curves to

from the above-mentioned typical set me given in be discussed later.

Figures 17 and 18. -M the e%iciency curves are

-— -
242 REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

Values of the

curve9 are given

ooeflioients read from these faired they would add bulk to the report and

in Table I. From these data the very useful purpose.

.07

.06

.05

.04

g

H

.03

.02

,01

0

T1

.

i?

FmuRE6.—B1adeformwuvw (C andR pro@era)

lbdlmrreter

%E&& tidth

Hadd$thiclmess

R- tfurad+

.08 .30

\

.6’

.07 Z8 R .7

.06 .24 6

.05 .20 5

t I 1 r I 1 I \\ I

t

m Wd-d--l

.02 .~

I N 1 ~ I I

.0/ .04 ~J

o 00

J 2 .3 .4 47 .6 .7 .8 .9 LOO

5

FIGURE6.–Blade form curves (S Propelka)

;~dfm#er

b=! ladewidth

;:~~~.hfckn~

R-tip IWuna.:

wouId serve no

curva may be replotted if one desires. The observed A comparison of the data at different tip speeds~can

data, though kept on file, have not been given, since be made from the cross plots of Figures 31,32, and 33.
FULL-SCAIJE TESTS OJ? NUITAIJ PROPELLERS AT HIGH TIP SPEEDS 243 .,

These plots give the maximum efE&ncy and relative

matium efficiency plotted against “tip speed”

~. -ar cross plots at other values of ~ lead

to the same conchsions and, therefore, need not be

ghn here.

DISCUSSION

Strictly speaking, tip speed should be defined as the

speed of the tip of the propeller along the hehcal path

traversed by it with reference to the air. This is equal

to the square root of the sum of the squa= of the

forward speed and of the speed of the tip in the plane

of rotation. At the low pitchee necessarily employed,

this -ralue differs very little (2 per cent maximum)

fmm the tip speed (m~n) due to the rotation alone.

For a ~ of 1.4 the difference is 10 per c~t, which i9

quite appreciable. We shall consider the term “tip

speed” as meaning the tip speed of the propeller (rlh)

due to rotation alone. Attention is ca&d h the fact

that in special racing propeks with high forward and

rotational speeds at high pitch angk, the actuaI tip

speed would have a somewhat greater value, and due

allowance should be made for this fact in applying the

results.

h mamiuation of the curves for aU the propeUem

reveals similar characteristics for each. The thrust

coetlicients, Figure 17, increase with increase of tip

speed up to a certain point and then decrease. There

is aLsoa crossing over of the cm-me so that the dynamic

pitch is lowered as the tip speed increases: This

crossing over appears almost as a fixed point up to the

speed where the thrust coefficient dropsl and then the

curves seem to shift to the left. The point of crossover is very close to the ~$ of maximum eilbiency.

The power coefEiciwds CF increase continuously with

tip speed, at first slowly and then more rapidly.

The change is also greater in magnitude at the lower

Talues of --J. (Fig. 18.) Computations indicate

that the smaII changa in the vahms of the thrust and

power coefEcieuts that occur as the tip speed is

increased up to the “ crit.icaItip speed” are due to the

deflections of the blades.

One would ~ect that, with the thrust and power

coefkients increasing, the e.flk.iency would not be

seriously affected. In fact, the changes in thrust and

power coeflicientaare at so sIowarate that the eftloiemy

is practically unaffected up to a certain speed. O?igs.

19 to 30, inclusive.) This point is more clearly

demonstrated in the cross plots of the maximum

efficiency against the tip speed of Figures 31 to 33,

imdusive. Clearly the dkiency is constant up to a

tip speed varying from 95o to 1050 feet per second.

The higher speed corraponcls ta the thinnest pro11

pelIers and the lower speed to the thickest propdler;

thin and thick referring to thickness chord ratio and

not actual thiclmmas.

The actual “peak” efficiency varied with the tbiokrwss ratio. In the case of the C series the thickest

propeller (C?-1O)had about 3 per cent higher eficiency

than the thinnest (C?-6) (72 per cent against 69 per

cent). With the R series the thinnwt propek (R-6)

had about 3 per cent more efficiency than the thickest

(R-1O) (66 per cent against 63 per cent). This difference in efficiency can be .sx@ined by the fact that

the R section is a poorer ‘airfoil than the Clark Y;

that is, the L/Zl ratio is lower for the R section than

for the Clark Y, especially at the low angles of attack

at which the sections me operating near “peak” efficiency. Since the L/D ratio of sections is a more important factor at lo-ivpitch settings than at high pitch

settinga, a 10VWXeflhiency would be expected from the

Leacfnq t I

=k!e h

.3.4-5~.7J9=5J i

S7.ATION [RL.LW251051 f12t.3 1.41.51 .s[.71-8[ s IRE

Ck7Q/?#AZORRIJO ~ .4/1.59179W5V.Ooj.slsf..sfilE71.745ei .351,U77

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ST4TI0.W z5L051. / 1.2 1.3 1.41.5 1.6 [.7 I-5’ IS I I

u?

L&%$2%%l-” 15%ER%WWW R3KW 5’

Propelferseciionbased on Clerk-Y

Rmmx 7.—Pm@ler rectlono@nates (C andR sec+ions)

R propellers. The mgle of zero Lifthas a lower value

for a thick airfoiI than for a thin one. The dynamic

pitch of a propehr will therefore increase with rm

increase of the thickness ratio with a resulting increase

in the “peak” efficiency because of the higher pitch.

The L/D ratio of the R section decreases so rapidly

with increase of thickness ratio that the advantage of

the higher pitch is overcome; and the thickest R propeller is the least efficient. On the other hand, the

decrease of the L/D ratio with increase in thickness is

less rapid for the C section. Hence, the thickest C

propeIler is the most efficient:

We note that the “peak” efficiency occurs at about

the same vfdue of ~D with the three R prope~ers. on

the other hand, the thinnest C propelkr “peaks” at ‘r7

a higher vahe of ~ and the two thicker C propders

--

at successively higher vaIues of ~~. The @ of

attack for mtium L/D ratio is lower for the C section than for the R section. Therefore, “peak” effi-

&ncy occurs at a higher value of ~~ for propellers

with c sections.

..—

...=

---

— +—

_.----

—

. .

--

. ---

—
244 REPORT NATIONAL M)VISORY COMIWTT’E13 FOR MZRONAUTICS

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FIQUBE8.—PropelIer R-6 set 9.6”at 0.76R.1,003r, p. m. FIOGRE9.—Propeller R-8 set 9,6° at 0.76R.1,203r. p. m.

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FIQURX10.—PmpeDe.rR-8 set9.6”at 0.76R.1,400r, p.m. Fmurm 11,—PropeUerR-8 set 9.6”at 0.76R.l,W r. p.m.
FULL-SCMJ3 T73STS OF METAL PROPEKJXIRS AT KU3H TTP SPEEDS 245

v

.07 .7

d

Q

C5

-1,

FIGCREl!L-RopeUer R-S eet 9.F at 0.76IL 1#00r. II. m.

-IT

Au!lti

0

0 J .2 .3 .4 .5 .6 ‘

~

nD

Pmcm 13.-Pror4Jler B-S set 9.@@ 0.7SR. 2JJWr. p. m.
246 REPORT NATIONAL ADVISORY

The fact that the C series propellers are about 6 per

cent more ef%cient than the R series might be taken

v

i%

FIGURE16.-Propellsr R-S set 9.6° at 0.75R.~W?l r, p.m.

to indicate a superiority of the Clark Y section for

propellers. These same propellers have been tested at

.07

.06

.05

.04

.03

c,

.02

.OJ

o

-.01

-,020

J .2 .3 ;4 .5 .6 .7

v

a

‘GmE17”-Ttit -Crent ‘s”:“ ‘m~er ‘4 m‘“~ at‘“’m”

other pitch settings up to 27° and the data are given

in Reference 9. The latter tests show that this advantage for the C1ark Y section disappears at the

COMMITTEE FOR AERONAUTICS

higher pitches where the L/D ratio is a less important

factor thm it is at lower pitches. In fact the R propellers appear superior at low values of ~~; i. e., high

angles of attack of the sections, where the Clark Y

section is inferior to the R section.

The- standard propellers have a higher efficiency for

the narrow than for the wide blades, since the sections

of the narrow propehrs have somewhat lower thickness ratios than the wide propellms ovm most of the

blade. (Fig. 6.) The tip thickness ratios are higher

on the other hand, and the tests show that the efficiency starts to drop at a lower tip speed tkm for the

wide blade wit~ the lower thickness ratio tip, The – ““–

average thickness ratio of these propellers is about-the

same as the ratio for the R-6 propelIer. The efficiency,

as would be expected, is about the same as that of the

R-6 Etthe same setting.

Referring again to the CT and CP curves, we note

that the speed of change or “critical speed” coincides

.03

—

c, I

, I I I I I l-%k

I f I 1 I I ! I I I I

00,,. -,

.2 “.3 # 5

v“

n>

‘&3mE IS.-pOWer CO@2klltVS. $- Pro@ler R-S set 9.6”at 0.7sR.

with that speed at which CT begins to drop and cp

to inc$ease rapidly. Above this “critical speed” there

is fit a gradual drop in eficiency shown by the bend

in th&curves (figs. 31 to 33, inclusive) and then a

rapid drop up to the limit of the tests. Test points

were not taken at close enough intervals to eatublieh

absolutely the shape of the bend, but there is no

reason to suppose that it did not follow the curve

througl the points.

The constancy of the, efficiency up to a certain tip “~

speed”suggeste the use of a ratio which we shall designate herein ‘(relative efficiency.” This is defined as

the riiiio of the efllciency at any tip speed to the efficiency at tip speeds lower than the ‘tcriticaI speed.”

Curves of relative efficiency are given at the top of .

Figurs 31 to 33, inclusive. This plotting places the _

various propellers on a fair basis for comparison; any

differences of efficiency that- they may have had at

low speeds are avoided. The striking feature of them

curves is.their similar elopes. From these curves one

sees mat, on the average, the efficiency of the propellers is unaffected by tip speeds of 1,000 feet per

—

second, but that at higher speeds the relative efficiency
FULL-SW TESTS OF XDITAL PROPELIJZRS AT HIGH TIP SPEEDS 247

i=%

PIGUZZ 19.—EI3chncy w. ~D. Propeller C-6 S& 9.6°at 0.75R.

.6 I 1 f /1/ .

//~;’ “ 7

A’ L-

.-

!060-1 r.p

I I I / //1 ,

..

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.6

S

5

FIGGE=3J.-EfO.ciencYvs.#D. Pro@er C-Snet9.@ at .?’5R.

.

.

-.

‘Fmmu 21.—Em&ncy m.:. Propeller C-IO set9S at.7tJL F1~m@22—E6iclerrcy vs. ~- Prq@lsr R-6 set 9.LPat .76R.

.
248 REPORT NATIONAIJ ADVISORY COMMI’ITEE FOR ~RONAUTICS

.

.7

6

.5

\

4

v

.3

.2

B ,

J

o ./ .2 .3 4 5 6

v

nii

FIGURE!Z3.-H%Cb3Y VS.$- PropeUer R-S mt ‘W at .76R.

0 ./ .2 .3 .4 .5 .6

x?

7

.,40U- [600 --- 9

f-l -.

6

I

.

.5

t

,4

T 1800.

.3 ,

.2

\l:l

I

i

0. ./ .2 .3 4 .5 .6

x? in

FIWIM z-i.-maclenoy~. +D” Prmeller R-10aet9.@at.76R.

.7

“1 I I i I I I I [ 1 I 1 I

?Ooo I I

1

I I

I

.0

.5

I I \\\lA. nl ,, ! ! 1 4

.2

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I I I I I I I 1! ,11,11I 1 I

II 1! 1111 o J .2 .3 .4 .5 .6

v

%0

FIwJax 2s.-EmciemY m. ~. Propeller C-6 sat6S at .76R.
17uLL-SCALE TESTS OF METAL PROPELLERS AT HIGH TIP SPEEDS 249

.

0 J .2 .3 .4 .5 .6

v

a

FIQIJEE ~.–EffiCiWlCy VS. ;;- Pmpeller E-W-9.6 set 6.S” at .76R.

.0 J .2 .3 .4 .5 .6

w

‘Fin

i%

F-rwJEz z3.-Emcierw VS. ~. ProPWer @-N+.5 W 6S at .75R.

7

‘1111111

I I I film-iaoo+vY /

...._

..

FIGUBE !Z9.-lMkienCY =. ~D. Pm@Ier S-W-9 set IF at .7M?.

S9300-32-17 .

I?I13m So.-mciency vs. + Prc@ier S-WE setI&at.7SR.
250 REPORT NATIONAL ADVISORY COMMWI’EE FOR AERONAUTICS

drops at a rate of about 10 per cent per an increase of

100 feet per second. These vrduee are easily recalled

and agree very well with the facts, but the reader is

reminded that they apply onIy h these low-pitch

propellem,

One or two other points axe mentioned in passing.

The comparisons between the propellers have. be~g.

Frmxm S1.-Compruteon of roaxtmrrmeftlofenotmat varfoae tip spaede. Prop911erW

set 6.$ and 9.fP at .75R. Propellem C-S and 10setO.@at.76i7.

Fmurts 92.-Oomparfaonofmaxlmmnef.?kfencfwat verkm tip sW. Propeller R-6 eat6.8° end 9JT’at .76R. Prop@Iera R-S and 10sat 9.6° at .76R.

made on the basis of “peak” efficiency, since it is one

of the most importamtpointe of action of the propeller,

We sJso riots that this point of maximum efficiency

v.

moves to lower values of :D- as the speed increases.

The change in efficiency near the “peak” is so smalJ

that a comparison at constant-value of ~ would show

the s~me result as was obtained at the “peak.” If

comparisons between the propellers are made at lower

values of ~~? one will find that similar reductions of

efficiency occur, as is evident from the curves. The

drop will be somewhat more rapid, because all tho

efficiency points must gradualIy converge and reach

zero At zero :D. The values of ~~ above peak cficiency are of little practical importance, Any comparisons here are likely to be erratic because of the —.

rapid change in efficiency with change of ~. In the

Al

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10 /2

Fmum8S.-Cc3n_n olmexfnmrn eftlcfenclm at varfous tlp~eads. Pro.

pallemS-9.5 set 6.&cd .76R. PropellersS-9 set W U .7fiR

case of a ‘plane diving at high speed, the decrease in

dynamic pitch and smaII increase in power at #o

higher speeds i@icate that a higher negative thrust

may be expected than one would estimate from the

reeuh of low tip speed tests.

A phenomenon of little importtince in the measurements, but of ‘&eat practical importance, is the production of noise. Even with the confining and damping action of the walls of the large tunnel building, thb

noise at speeds above 1,000 feet per second was disagreeable more than hfdf a mile away, and could be

heard more than a mile and a half away. Within the

test chamber a most penetrating sound prevailed,

which could not be rendered agreeable by any known

methods or by new ones devised for the occasion. Tho

whole structure vibrated, effectively shaking down any

dust and loosening all insecure parts. The observem

noticed, however, that the cockpit was the least objectionable location and any point in the plane of the
FULL-SCALE TESTS OF METAL PROPELLERS AT HIGH TIP SPEEDS 251

propel~erand ahead of it, the worst. A change in the

characteristic roar of the engine and swish of the propeller appeared quite suddenly at about the “ mitica~

speed.” At higher speeds a high-pitched unearthly

whine prevailed. This fact indicated that the speed

at which the ticiency begins to drop can be predicted

quite closely from this change in the characteristic

sound. A study of the problem of noise is now being

made at this laboratory with a view to isolating the

predominant frequencies and developing means for

their elimination.

Theoretical discussions of compressibility involve the

velocity of sound in air. At this ~elocity complications appear in the usual theory. In fact, it is commonly supposed that the velocity of sound is the &k

ical point in the speed of bodies. This is about 1,115

feet per second at 60° F. The fact that the test results

show a lower “critical speed” (950 feet to 11050feet

per second) is explained by the circumstance that there

are points in the fluid, over the top of the bladw, where

the velocity is greater than the relative -ielocity between the free air and propeIIer tips, on which our

calculations are based. This conclusicm is substantiated by the fact that the thick propellers which have

the highest intake velociti= also have the lowest

‘~critical speed.”

FinalIy, the rewdb of these tests confirm those of the

earlier full-scale tests of Reference 6 so far as the latter

apply. They also agree qualitatively with the results

of the airfoiI tests of Referent= 2 to 5, inchsi-re;

namely, that thin sections are 1S affected by high

speeds. These airfoil tests also indicate that at high

speeds a section in the shape of a circular segment is

superior to others. The agreement between results of

the tests of the standard sections and the propeller test

results leads to the conchsion that there might be some

advantage in building a propeller with Rections which

are segments of circles near the tips, gradually running

into standard sections along the blades. It is hoped

to take this matter up in later teds.

Most of the practical questions concerning high-tipspeed propellers me answered by these tests, since they

were made under full-scale conditions. Their lack of

agreement with the rwdts of model tests may be

traced to the fact that the importance of scaIe increases

at very high speeds.

The question may arise, “Are the results of these

twts with low pitch diameter ratios applicable to propellers of the pitches normally used?” While the low

pitches and velocities were, unfortunately, made necessary by the limitations of wind tunnel equipment,

clearly the high relative veloaties of prope~er and air

were actually obtained. It is to be expected that.,near

maximum efficiency, the angles of attack of most of the

sections of a propeller will be about the same, whaterer

the pitch. The classical Drzetiecki blade-demerit

theory of propellers shows that the ideal eliiciency of a

propeller section is

tan ~

~=tan (Q+7)

where TT

r= radius of the section

By substitutingin thisequation the measured vaks

of efficiencyq and the values of @ computed from the

vahws of -$;I TAM of T can be obtained. On the

assumption that, at matium efficiency,m@es of

attack are constant for all pitches, these dues of ~

wiII appIy to other pitches. By substituting these

values of T and new values of Oa tabIe can be prepared

or curves plotted showing the mdue of efficiency for

any pitch at any tip speed. This computation is but

slightly modified by the later -rortex theory of Glauert.

Other ways of making this transfer to other pitches

may suggest themselves to individua~ designers.

The most reasonable conchwion developed from these

tests is that high tip speeds are to be avoided; first-,

because of the disagreeable phyaio~ogical effects, and.

second, because of the lowered eficiency. Since noise

is one of the serious problems of aeronautics, energetic

efforts m being made to reduce or eliminate it. Attempts to reduce the noise of high-speed propellem

promise little succes Wlt.h the increase in the number of geared engines driving large sIow propellers the

advantages ,of high pitch as welI as lower speed me

realized. There will still be some use of high-tip-speed

propellers and the data at hand will be useful in the

analysis and deeign of such types.

CONCLUSIONS

—

1. The e&kn.cyof standardmetalpropellers ispract.icaIIyunaffected by tip speed up to 1,000fset per second.

2. Above a tip speed of 1,000 feet per second, the

ef&iency, relative to that at lower speeds, falls off; for

propellers of low pitoh (6.S0and 9.6° at 0.75R), at a rate

of about 10 per cent per 100feet per second bcresse.

3. Propellers with low thickness ratio tips can be

operated at slightly higher tip speeds than thick tip

propeIlem without loss of efficiency.

4. Tip speeds approaching the veloci~ of sound, or

above it, are to be avoided not only because of the loss

of efficiency, but because of the disagreeable sound at

these high speeda.

LAKGLEY klEMOEIAL AERONAUTICAL LABORATORY,

~ATIONAL i%DVISORY CO=I~EE FOB AERONAUTICS,

LANGLEY FIELD, VA., AToremher6, 1930.

-.
262 REPORT NATIONAL ADVISORI- COMMI’ITEE FOR AERONAUTICS

REFERENCES

British Aeronautical Researoh Committee: Reports and

Memoranda Nos. 884, 1086, 1091, 1123, 1124, 1134, and

1174.

Briggs, L. J., Hull, G. F., and Ihyden, H. L.: Aerodynamic

Characteristics of Airfoils at- High Speeds, N, A. C. A.

Teohnical Report No. 207, 1925.

Caldwell, F. W., and Falea, E. N.: Wind Tunnel Studies in

Aerodynamic Phenomena at High Speed, N. A. C. A.

Technical Report No. 33, 1920.

Briggs, L. J., and Dryden, H. L.: Pressure Distribution over

Airfoils at High Speeds. N. A. C. A. Technical Report

No. 255, 1927.

Briggs, L, J., and Dryden, H. L,: Aerodynamic Characteristic of Twenty-Four Airfoils at High Speeda. N. A. C. A.

Technical Report No. 319, 1929.

Weick, Fred E.: Full Soale Tesk-on a Thin Ivletal P~opeller

at Various Tip Speeds. N. A. C. A. Technioal Report No.

302, 1928.

Cowley, W. L., and Levy, H.: Aeronautics in Theory and

Experiment, Chapter IV. Longmans, Green and Co., 1918.

Weick, Fred E., and Wood, Donald H.: The Twenty-Footi

Propeller Research Tunnel of the National Advisory Committee for Aeronautics. N. A. C. A. Teohnical Report No.

300, 1928.

Freeman, Hugh B.: Comparison of Full Scale Propellers

Having R. A. F. 6 and Clark Y Airfoil sections. N. A. C.

A. Teohnioal Report No. 378, 1931.

TABLE I

FINAL ADJUSTED COEFFICIENTS

PROPELLER C-6 8ET 9.6” AT 0.76R

TABLE I—Continued

FINAL ADJUSTED COEFFICIENTS< ontinued

PROPELLER C-b SET 9.6” AT 0.75&-Oontimr@

1.

2.

3.

4.

5.

6.

7.

8.

9.

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2,166r. p. m. 2,%3)r. p. m.

0.10 0.0670

.0646

:E . (U97

.26 W&

:: .0311

.40 IO&

.46

.m . (WI

.66 ---... -..,

:;: a M12 am

.06W ,0247

.20 .OW . 02a6

.25 . 047s .0216

.bo .0406 .0192

.66 .a224 . olm

.40 .0144

.45 :% .0117

.EO .C4ra7 .OCW

0.242

.s64

.469

.666

.626

.08s

.6s0

.854

.liw

am

:g

%

.26

.46

.46

.66

acw

.0697

. 0M2

; p7&

:%2

.0165

.ml

a 267

.SIU

.460

.662

.6M

%

.s46

..536 — ---
FULIJ+CALE TESTS OF METAL PROPELLERS AT HIGH TIP SPEEDS 253

TABLE I—Continued TABLE I—Continued

FINAL ADJUSTED COEFFICIENT&Continued

PROPELLEE C-10 SET LOOAT 0.76.E

FINAL ADJUSTED COEFFICIENTS-Continued —

PROPELLER R-6 SET 0.6° AT 0.i5R-COnthmed

l,MO r. p. m

v

I

CT

I

CP Z—D

1,401r. p. m. I@ r. p. m.

—-— .-—

v

n—D

a 10

.15

.20

.25

:% m;;

CT CP v

0.0656 0.Olsi :2J

.am . Oms

. M49 .0179 .022

.0392 . Caio .576

.0a80 .0150 .622

.0145 :s .m29 :Z .0142 .Om .W2

.0)7s .Om .452

0.10

.16

O::SPSI o:sf&

.al .0611

.021

.0m2 :E := .OIW

.35 .0176

dz& . O13U

:: .0126

:: -.-.:? _.:

am

.Xia

.4s5

.602

.623

.874

.707

. 7al

. no

.640

0.10

.16

.fa

.25

.al

::

.46

:~

o.LMo7 0.0214

.0564 .0216

.0510 ; ~4

.0406

.040-s .0195

. m47 . Olm

.02s6 .0102

.0222 .Ola’a

. Olctl .0113

.rcm .00752

0.258

.399

.4M

.%4

.627

. 67a

.7M

.7!4

.7CS

.65

0.10

..15

:Z

.s0

.66

::

.s

: ~i Q Olm

. OEM

.0460 . owl

.0402 .0174

.a?42 . Olui

.Ozs .0133

. ms

: E7 .0111

. IXT6 .0m4

Il!m

.409

.6C0

.m

:!2?

.646

.605

.46a

I

I@Or. p.m.

l@l r. 9. m. 2@0 r. p. m. 1,40)r. p. m.

(tlo

.16

..ZI

.25

:8

.40

-46

.60

,

CLlo O.om o.01E3

.16 . 05s1 .0196

.20 . 04irl . mm

.23 .0414

.60 .0351 %%

.0zs5

:ti .0217 :$%

.45 IO& . Olu

.53 .02$4

a 225

.40i

.6C0

.m

.62a

:E.E%E

.435

: ~o aoza

.0221

.050i .0210

.0(42 .0195

.cm .0179

.LWO .OILU

.02z7 .0139

.0146 .0U2

.(056 .0059

0.20s

.2a2

.484

.;g

:&l

.90)

0.2s5

.W2

. 4ss

.665

.629

.676

.707

.72

.m

.66

0.1o

.la

.20

.26

.s0

%

.45

.60

.65

!@) r. D.m. 2#Ylr. p.m.

--

1#30r. p. m. !2J03r. p. m. O.1o CLW6 I

.M .05io ,

.20 . 052s

.aa .0463:

.24 .ma

.2.a .CW6 ;

.40 .02a2 ,

.45

.03 :&#[

a 0240

.022a

:~

.0192

.Olm

.0142

.0u3

.Im2

a 10

.16

.20

.%

.X1

.a6

.40

.46

.m

a 10

.15

.20

.25

::

.40

.45

.50

.66

U&5 O.mas

.0265

.0552 .0223

. w .0217

.0427 :12g

.0262

.0295 .0167

.02?0 .0144

.0155 .0109

.m .Woa

am

.8W

.4s4

.66s

.627

.675

.ml

.72)

.71

.647

0.10

.16

.m

.25

.al

.65

.40

.45

.60

.56

I O.W i

.Oma ;

.0546

.04!z3 !

A&I

J180aI

.0147

.alm

0.0256

. m2

.0247

.0287

.0224

.0236

. Olm

.0147

.0M7

.CMo

ams

. a47

.442

.625

. W

.647

.SW

.710

.ss6

.6ss

,

2#31r. p.m. 2@l r. p. m.

a 10

.16

.20

.!25

:%

.40

.46

aosm

.0357

. ml

.0466

.0a90

. mls

.LYQ6

.0U40

aom I

.0261,

.0240

.022s

.0z06

. 0M2

.0160

.0116

aao Clmn[ llouo am9

. Olsl

::

.672

I

-ml I -01* .64s ZZ12r. p. m &—

_=

—-

Ltm?is az?a

.02i2 . U9

.0252 .405

.0251 . 4i2

.0236 .6a4

. Om .575

. 01S7 .605

. Olm . m

.0107 . 5i4

0.10

. M

.2)

.E

.20

.s5

.40

.45

.50

.66

0.06

:=

.Owu

. 04a5

.I-nn

.lm4

.0233

. OIEO

.W5

0.!226

:2

.501

.Ea

.m.647

.em

.615

.267

a 10

.15

.20

.!26

.W

.as

.40

.46

.50

PRO PELLER R-S SET 9.@ AT 0.76.R

-

1,001r. p. m. 1

1,2(Mr. p. m.

a 10 11o563 a mm ama a 10

.15 .0524

u& am a2a6

. Ols’s .40a .16

.20 -0476 .Olua .4Q2

.0199

.Sil

. 4C3

.26 ;C& .0190

. @is9

.659

. Olw

.Za

. 4ea

. 04s4

.Su . 01s1 .tca

. olP4

.X1

.669

.aa

.mia .ms4

.0167 .&u .&l .W.19

.607

.40 :Pti .0152 xig

.0170

.4Q

.&26

.45 .017 . ma7

.0244 .m64 . 6s4

.45 . OH%

.50 .01a2 . m15 .477 .60 .0106

.634

:E t .m

I

MO r. p.m.

a 10

.15

.!21

.25

.S1

.35

.4!I

.46

.60

a Lm5 I

.0567

.0517

:%x

.Lu40

.6274

. Om

.01

U?&

. om7

.025a

.0242

.O!a

. Olm

. Ouu

.m

0.22

. m

. S7

.455

.605

%

.5s3

.51

l“” u t F

-—

1,401r. p. m.

:% 0.10

.16

.494 .m

.Wo .25

.6M .al

.6M .36

.634 .40

.E31 .45

.A-o .W

!

a232 a 10

.W6 .16

.4ss .20

.500 .2s

.620 .30

.m$ .65

.53s .40

.W .46

.466 .50

m r. p. m.

-.

aw

.433

.491

.W

.Om

.6a6

.C3b

: Y=

a 10

.15

.nl

.25

.33

.65

:i!

.50

aoaia 0.0202

.Oml

ii% . ON

.042s . Olm

.OsOa .mm

. 0s07 .0169

.0241 .OM2

.Om .ola4

.01(0 .Duo

1~ r. p. m.

-

PRO PELLEE R-6 SET 9@ AT 0.75R

1,(C41r. p. m. 1,203r. p. m.

2pJl r. p. m.

am

.409

.SM

.575

.626

.650

.654

.5m

.4R1

a 10

.15

.m

.25

.al

.aa

.4Q

.46

.Eo

:Cs&

.M40

:%%

.Om

.0210

.0147

. Wm

O.m

.4!M

:%

.62s

.Ek9

.647

.s26

.465

an LIIM& a 01S4

.01s2

:: .0441 .0176

.26 .W .01676

.CB2a . 0E8

% J3z& .0145

.012J

:: . 0M6 .0110

.m .0?i7 .m

am aom [ ao2u3

.15 .O.S6A I .0214

“.20 .0506, J_Eck&

.O-w

:: X3& . 01S8

. Olia

.40 .0247 . 01!!3

.46 . am . ola4

.50 . Om .0110

U6&I

.Omo

.0474

.0410

.Ow

.02m

.01s1

.C067

.— —

.-

----

-
254 REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

TABLE I—Continued

FINAL ADJUSTED COEFFICIENTS--Continued

PROPELLER R-8 SET O.OOAT 0.76R-Contimred

TABLE I—Continued

FINAL ADJUSTED COEFFICIENTS-Continued

PROPELLER C-6 SET 6S AT 0.7SR-C!ontlmred

alm r. p. IR 2#Or. m.p. @OOr.p.m. 1,600r. p. m.

11T’ Cr C!r

~D

0.10 a 0615 0.0261

.la .0576 . @247

.m .0240

.!4s :!?%

.30 .0412 :%%

.35 .OW

.40 .0276 :%%

.45 . 01!?4 .0155

.50 .0101 .0123

4=-l-4- Cr CP

. —

0.0614 o.02Ml

.05n

. Ma :%

.0464 .02W

.04@l .0222

. ma Jl&

.0255

.0177 .0164

.0@3 .0134 m

v

a

CT CP v

\ g 0.0414 c1OB3 o.3%

.CW7 .0124 .444

.20 .0313 .one .530

.25 .0257 .0109 .6%)

.30 .0195 .(m95 .615

.25 .Ol!a .W76 .520

.40 .Wl) .0051 .4n

Q

0.246

.350

.443

.515

.69s

g

. W4

o.m

“:FQ .487

. Ml

.576

.50s

.618

.350

alo

.16

.20

.23

:%

.40

“:$

0.10 0:p& o.Olm a 324

.16 .0125 .441

.Z1 . owls . Olm . @al

.25 .0257 .0100 .590

.2Q .0191 .619

. as .0137 :% .CJxl

.40 .W7 . W4s . 4?6

I I 1#30 r.p.m, 2JO0 r. “p.m.

2,3CQ r. p.m.

0:;: aw 0::J

.0877

,20 .0324 : :;3

:3 ~ :!% .0m6

. C47b

.40j :IR5 .@149

a 10 ao452 0:M)

.16

.20 :% .0128

.25 .0116

.20 .01s% .0097

.35 .Om .am

.40 .KUt .W43

am

,438

.52A)

.54M

.618

.bs$

.am

I

1 I

—“

:%

.504

.576

. M3

, M6

.m

2JOOr. p.m. 2J~ r. “p.m,

PROPELLER R-10SET 0.6°AT 0.7SR

0.10 a 0471

.15 .0414

.20 I

%/&J [

::

.35 .o127 !

.40 .W47

!

i“o155

.0146

.01.34

.0119

.0290

.0076

.rm43I

a 204

.42d

. a!x

.593

.6.13

.690

.203

0.10

. M

..ZI

.26

.30

.35

.40

0.0464

.0418

.0555

,0284

.Omu

.0136

.K135

0.0159

.0153

.0141

.0124

.0104

.ma

.(04!35

l,@31r. p. m. 1,203r. p. m.

0.10 acw 0.0216 0.270

,15 .0&s9 .0214 .391

.20 .0507 .Oml .430

.28 .547

.30 :%% ! :%% .595

.35 .0$42I ,0192 .628

.40 Cr283i . Olm .620

.45 :0231

.W .oleQ [ : :;% :E

a 10 0.060s 0.0219 0.278

.1s .CE82 .0216

.!al

.391

.0510 .0213 .480

.% A& .Om .547

.22 .0202 .505

.0347 .0195

:!l .0202

.&#

.0130 .63$!

.45

.IK1

.0172 .axl

:%% .0152 .536 a266

.805

.451

.&la

.5M

.406

—.

,..

.—.

2,300r. p.m. 2,400r. p. m,

a 10

.16

%

.W

.85

a 0470

.MS

.Wr4

. Om

.0165

.C#4

a 0M3

.0172

. 0U8

.0136

.0110

. owl

CLg 0.0469 0.0171

.0418 .0163

.al .0355 .01s0

.25 .0270 .0124

.al .0197 .0107

.85 .0110 .Own

.40 ,0018 .0051

a 274

.284

.474

.5M

.m

.m

.141

1,4UIr. p. m.

0.05’36 0.0214

. 05f2 .0218

.0515 .0211

.Mao: .Oims

.0407:

.0350i :%

.wx43I ; :pa

.0217i

.0149! .0145

1,600r.R.m

o.0+310 0.0216

.0570 .0215

.0523 .0214

.04!?4 .0212

.MO

.0353 %%

. @at! . 0L32

.0220 .018$

.0155 . OWJ

0.282

%

.562

:%

.632

:%

0.10

.15

.m

.2.5

.%’

.40

.43

SW

o. %2

.6S2

.4s9

.552

.003

.628

.633

.m

.518

0.10

.la

.2)

.25

. .

.;

.40

:ti

2,S33r. p.m. 2@0 r. p. m.

0.0176 a350

.0114 .45s

am lug 0.0164 0.400

.25 .0143 .442

.0159 .0118 . 4ao

~ :R .0041 .0041 . a12

I,W r. p. m. 2$00r. p. m. 1 I I

.

2,700r. p. m,

0.10

.15

.20

.25

.32

.35

,40

.45

.50

0.0624 0. 023a 0:pJ

; ~2 .0234

. m2 .4ea

,04a5

.0425 : E7 :%

.0363 .0204 :~

.0297 . Ola$

.0230 .0170 :~

. Olal , . Olw

., 0.10

:.U

.:3

.,..

.%.40

.45

.C41

0.0930 0.0202 0:‘2&

JJ5& .0359

. 02s2

.04w %i

. Ma :K .5?4

,0876 .0220 .503

. O!m .803

%% .0133 .678

. Olao .0161 .4s7

..

—

PROPELLER R-6 8ET 6.& AT 0.75R ...

.-

.

1,000r. p. m. .— 1! l,XMr.‘p.m.

23UI r. p. m.

I I I

0.10 :$36: ~ ~&6 a334

.16 .aa

.!al .0387 .0207 I .402

.0437 .0256

:: .0429

.476

.0242 .581

.35 .03e4 .0229 .556

.40 .03m .0212 .E412

.46 ,0191

.50 := i

t

.0169 :%

a 10

.15

.Z1

.25

.XJ

. .

.8

,: .45

“.&l

aow : g7m2

.0654

.Oall .0204

,0461 .02b7

,0404 .0247

.Wo .0221

.02?a :=

.0191

.0108 . OIM

a 316

:!%

.449

.4$4)

.516

.518

.470

.%46

.i- ,

1,420r. p. m,

~’” 1,620r. II. m,

0.10

.15

:3

.30

.65

.40

0.0416

.N.67

.CK!1O

.0231

.Olaa

.0125

.00!15

Lla& 1

am’ 0.04zI 0.0130

.15 .aM8

~ 62;

.516

; Cii

. m12

.& :% j!2#

.816

.0112

. 5m .20

.864

. Olw

.616 .35

. bm

.0125 .ma7

.X@ ,

.tn4

.40! .0055 .0072 .305

PROPELLER O-6 SET 6.8” AT 0.75R

1,003r. p. m.

II

1,2Wr. p. m. ..>—

—~11 .. 1 .1 I --

0:~ ao4c8

.W33

.20 . 031a

.23 A&2

.al

.85 .0140

.40 .0074

Q 0145 0:ho

.0167

. Olm .614

.0118 ,5M

.0124

.COm :E

.W73 .n4

.=
FTJLL+SCALE TESTS OF METAL PEOPELLJIRS AT HIGH TIP SPEEDS 255

TABLE I-Continued

FINAL ADJUSTED ~EFFIC~N~orttinued

TABLE I--Continued

FINAL ADJUSTED COEFFICIENTS-Conthnwci -- ..-—

PROPELLER B-6 SET 6&AT 0.75R-ContinuW PEOPELLEB 6-W-9.6 SET 6.8”AT 0.761i-CoE.thmcd

. — .—

2200 r. p. m. 2$00 r. p. m.

I

3 [ G Cr I

t

.—

CT

I

Cr

I

T

..-—

--1- Cr 1

c?

CLOIW

. OIsl

. 01s

.0124 .0107

. 00DL

.00T3

. . .. . —-.

,..

am amm Rozm 0.H6

.10 N42& .216

:&% .m4

:: .Olm .s4s

:Z .0170

% . Olio . Olm :E

.a5 .0m2 . 0L32 .217

0.10

.15

.20

.26

.30

.66

.40

: ~n

.0347

.0272

.019s

. Olx

.CuM6

a W-4 o.Oms llzaJ

.0414 .0165

. 0s46 .0142 .4s0

.6M

:% :M

.0111 .0021 :%

.

,-

,-- -

.......

I I --

2#13 2#30 r. Q.in. PROPELLEB S-N-9.6 SET .9S AT 0.76R. r. p.m. II -——

l,MI r. p. m. 0.046s CL0179 0.266 0.1o h M61 o.ols4 0.251

. Olm .2CS .m -Mos .0172 .352

:% . Olm .4m .m .m26 . Olm .427

.0264 . Olsa .4m .35 .02m .0127 .466

. 01s4 .0114 .494 .s0 .0167 .0116 .4s2

.M96 .mQ4 .M7 .66 .Mi7 -m .!WI

wr. p.m. I 2#00r.P.m.

0.0L59 : 01911s’0.!235 0.10 CLOW 0.Olm am

.mm .s32: .16 .0s77 .Olss .MI

.mm .Olm .693 .20 XC&’ .m66 .872

.023s .0142 .0 .26 .0147 .m

.0162 .6i4: .s3 .0146 .0126

:%! .2M

.Ms

.m32 .66 .M66 .0104 .lm

E03r,

ao5 a M9s

.10 . WI

.15 A%&

.!a

.=

.s0 %J

.s5

.46 .Oms

L m.

o.Olm o. Ma

.0118 .814

.0116 .493

.0111 . 6W

.mrm .M3

:CK& .m

.621

. lm76 .25s

a 10

.15

.20

:&

.65

___

.. .-:

Cm9& a 0110 am

.0111 .630 ‘

. rm6 .0110 .44

.0m2 . 01C6 .622

.02s5 . 0W4

.0165 .0m7 :%

. mm .Omi .5m

.0m5 .mi4 .851

ao5

.10

.16

.XJ

.25

.60

.65

.40

---

.-=..

a 10

.15

.26

.25

:%

l,Zll r. p. m. 1,40) r. p. m. -— —

~ :)4 a 176

.6M

.0113

; 1#111 :E

.67-I

.(XXS A-&

.0m7

. M74 .349

am

.10

.15

.al

.26

.s0

.25

.40

aum

:%%

.02m

.M44

.01s7

.m26

.OWI

:o& ]

.0117

.0118

:& I

.60s6

.Ooio

PRC)PELLER 6-W-9.6 8ET lk~ AT 0.i5R.

800r. p.m.. l,Kk)r. p.m.

.

—A

aa6

.10

.16

.21

.25

.s0

.s5

:2

0.0476

.042

.CMo2

. mE4

.C@Y1

.0240

. Olsl

.0117

.M4S

aauo a 170

. Olm . m

.0140 . 4s1

. OIW

.mM I %

.01a7 .670

. m17 :~i

:&%? I .267

ao6 o.% [ ao~ a UT7

.10 . .0146 .810

.15 :0293/ .mm :g

.m .rma .0186

.25 .Ozm .0160 ;664

.60 .0227 -mm .6!3

.66 . 0M?4 .Ouo .6M

.40 .mm . m95 .4M

-—

1$60r. p. m 1~ r. p. m.

.-

ao5 0.0451 0.0124 0.16s

.10 . W16 .0160 .6M

.15 .(Ss6 .0M5 .=

.m . muo . 0U9 .6m

.25 .0251 .mlo .5m

.30 .0191 .O1oo .676

.&s .Olm .msa .6M

.40 .W.2 .M72 .345

am aw o. oIm 0.176

.10 J-1& .Olm .s23

.Olal .444

:ti .mm .0117 .624

.25 .0250 .0110 .E@

.0191 . Olal .673

:%’ . 01% . 6M

.46 .0062 :%% I .W1

I

1#00 r. p. m. I,4M r. p. m.

mm

. m

.426

.tm

.E46

.660

.6m

.265

ao5

.10

.16

.m

.26

.20

.s5

.40

a m9

.am

.426

.607

. Lw51

.655

.601

.m

aos

.10

.15

.m

.28

.tia

.65

.46

.

I 1

I

2,011r. p. m.

1

2#0 r. p. m.

rIi:$4&g o. oIm a M4

.M60 .272

.M62 : pbubl .360

.0s21 .461

.0%6 . mm .m5

. Olm .0111 .4m

.0107 .mm .2S5

.Oom .mis .164

am.

.10

.15

:E.20

.35

.40

0.0$64

.M25

. m%

.0s23

.0m3

. Olm

. Om

.Wi8

a 0160

. 0M6

. OHS

.Ol!B

. Oils

. OIM

.WI

.0075

a 166

.Xs

.41!J

.M5

.ma

.560

.4ss

.6M

MY) r. R. m. 1$00 r. p. m. —

ao6’ .O. M62 a om a 165

.10 .0427 . Olm . MO

.15 .Ma6 . Olm .426

.m .0836 . Olm .Ea3

.25 .0277 .0E7 .646

.02141 .0117 .(W

:3 .0148 Xl& .4m

.40 .mis ~ .361

ao5

.10

.L5

.m

.25

.al

.a5

.46

——

2JO0 r. p. m. 2#M r. p. m.

2JX43r. p. m. 2@l r

ac8

.lo

.M

.22

.%

.20

.as

aow a OHS am

.Cnls .0172 .!M

.mm .0161 .%

.Mai .m49 .4!X

.0225 . Olm .4%!

.oM1 .mls .4U

.0M4 .O1o1 -201

aow

.041s

. Mm

.02$3

.0m2

.Olxi

.mm

ao6

.10

.15

.2)

.2S

AJ

o. Ml

.7ict

.ti

.&

.E4

:2

.Sm

am Q0566

.lo .04s6

.M .0426

.3

.26 :%%

.s0 .0m6

.23 .0133

.40 .004s

~II 0.14

.!2%

. Olm .3SI

. 0L59 .45!

. m46 .6M

. Olm .ml

. 0U5 .C1

-m .2X

2$M r. p. m.

2,400 r. p. m. 2@0 r. p. m.

ao5 amso amm am

.10 .0476 .0107 .24

.S6 .0413 . 01S6 . aw

.m .0245 .Cam .6%

.26 .02i6 . Olm .4s

.24 . Olm .0140 .4a

.s3 .0102 ::) .29

.40 .0039 .m

aw a 0624 :Qz& am

.lo .0M6 .2a

.15 .0403 . Olm . au

.m .0?3s .01S4 .2a

.26 m# . 0M3 .247

.20 .0144 .26

.86 .m . Olz .24

ac6

.10

.16

.m

.25

.60

.s3

a 04io

.0423

.CG60

.02m

.M25

. Olm

.m76

6..

. m75

. Olm

. m44

.Olm

. 01Q2

o. Ifi

.22

.Sol

.261

.29

.tm

.m
256

FINAL

REPORT NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS

TABLE I-Contiiued

ADJUSTED COEFFICIENTS-Continued

PROPELLER S-W-S SET lLP AT 0.7JSE.

TABLE I-Continued

FINAL ADJUSTED COEFFICIENTS—Continued

PROPELLER S-N-LISET 10° AT 0,75R-Contfnnod

1,400r. p.m. l,XIOr. p.m.

CT

K

CP

1,’220 r, p.DL 1,4Wr. p.m.

CT ~

nD

CLIJ

:E

.60

.86

.40

.46

.60

.M 1

G CP v

0.0676 0.. O.%a

.a5a7 .402

.04m .0199

.0440 . 01% %J

.m87 . Olas

.M27 .0177 .646

.0266 .0161 .662

.0193 .0143 .62a

.0120 .m% .682

.0032 .0100 .341

n—D

v CP I ~ v

m v

r12JJ

.4M

.666

.026

.607

.677

.540

.550

.300

— —

aom CL%

. 01!38

.01s5 .4Q2

.0191 .664

. 01a4 .619

.0175 :%

.0162

.0147 .6a7

. Ol!w .653

.0104 .407

0.10

.16

.m

.2J

. So

,36

AcJ

,M

.65

am

.16

.%

.an

.26

.40

.46

.C4

.65

cLo& a 0179

.Olm

.0442 .0130

.a327 .0176

.m47 ;m3

.02s2

.0267 ;~lJJ

.0172

.0110 ,Olcm

.0042 .0077

ao532 a01S2 :fi

.04m .0182

.04m .0182

.0400

.600

.Oln .678

,0247 . Olea .667

.0!B9 ,0160 .674

.0230 .0136 .676

.0167 .0117 .641

.0101 .0024 .667

.003a . mio .2W

1,6CUI p.m. l@30r. pc m, 1,0) r. p. m. l@O r. p. m.

-

0.10

::

.2JI

.35

.40

.45

. .

.2

a 10

.16

.X1

::

.S6

.40

.46

.60

.66

0.297

.407

.496

.Ms

.620

.659

.mb

.628

.653

.2QLI

0.0538 0.Crm

.0562 .0207

.0439 .0202

.0t4b .01s8

.02s8 .0153

.03x .0177

.ml .0160

.0124 .0141

.0125 .0118

.0352 .m

aob50

.Uc3

.0456

.0402

.0247

;&#

.0100

.lxB6

0:~

.26

.23

.30

:!!

.46

.60

.66

o.05m

; O&;

, 041s

.M90

.02aa

.0236 .0166

. Olal

. ml

:;!

.20

.26

.&l

.26

.40

,43

AJ

0.2s7

.4ao

.489

.684

.612

.640

.6M

.618

.682

.640

a.ma

.40U

.491

. ml

.612

&

.620

. Eao

.811

I

2@2 r. p. m.

,

2,1C0r. p. m.

1 1

2,0XIr. p. m. 2J01r. p. m,

0.0339 0.0234

.05s7 :%! :% .Oxo

.0128

.0340 . Olsa

.0270 .OMb

.0183 .0144

,0122 . 011s

.0248 .m

0:;:

.X1

.26

.2$

.35

.4(I

.46

:%

Lla7!&

.4s0

, MQ

.618

.660

.666

.618

.617

.281

:IJ

.m.%

.30

.26

.40

.45

.60

0:M&

.0546

.04sb

. IM3

.W8

.0270

.Olw

. Ol!a)

R23S

.269

.4M

.649

.616

.855

.654

.6.2S

.603

0.1o

::

.ab

.30

.86

.40

.46

.60

aobsa

.0b2e

. 0M2

.0430

.0274

.0311

.0245

.0176 .

.0106

a 10

. lb

.20

.26

. ao

.86

.40

.46

.&a

aoma

.0627

. 04E3

.0436

.0279

. mm

.0232

. 01s3

. moo

:Z&

.4a

.646

.ml

.65(I

:%

.610

1

2JOI r. P.m. 2#M r. p.m.

2,X76r. p. m. 2@0 r. P. m.

::

:E.30

.26

.40

.46

0:~ a 232

. 3s4

.422

:&l . 4@a

.0z16 .669

; y& .608

.W

. Ola .656

aoaba

.0232

.0244

.0232

.0217

.0196.

.0172

.0144

. Olla

0. 06?7 0.0229 0.241

.0232 ;%

:% .0222

Al& j2& .622

.bm

.CL210 .0172 .820

.0241 .0151 .640

.0182 . Ol!n .670

a 10

. S6

.!M

.26

.60

.36

:2

.60

0.0640

.0599

.0660

. 04S6

.0420

.0268

.02M

.0196

.0124

a 10

.15

.20

.23

.&l

.36

.40

.46

0.ma

.0696

.Osm

. IM96

.0430

.Ow

.02s6

.020b

a 0%’6 :g

.026a

.m58 .423

.0242 .603

.0227 .667

.0x16 .614

. Oleo .636

.0162 .S@3

2,402r, p. m,

0.0560 0. Omo a 817

. obo5 ;@& .404

.0450 .433

. a284 . oa14 .bm

. C@lo .ms .676

.0222 .Olso .680

2,WI r. p. m.

Z4C0r. p. m 2JO0r. p. m.

0.16

.20

.26

.20

.35

.40

a 16 a 0610 0.0276 a am

. OJ62

:% :% :%

.24 %% .0232 :g

.M4b .OxrJ

:E A& .0182 .mo

,46 . OIM .648 2,600r, p. m.

PROPELLER S-N-S SET 10° AT 0.7bR .

0:g 0.0258 0.0221 0:~

; :29; .0126

.40 . olm .511

II I,C03 r. p.m.

ams

.402

.496

.669

.824

.893

.672

.641

.549

,296

3tll r. p. m.

a 10 a 0513

.16 .0434

.24 .0450

.x

.X1 :%%

.26

,40 :&#

. Olm

:2 .0118

.65 . W48

IUEJ a IO : p&

.16

.603 .0446

.674 .% .0402

.621 .20 .0364

.640 .36 .02Q(l

.s20 .40 .0240

.681 .45 .0179

.4s2 .60 .0115

,266 .6-s .w4a

: M&

. Olaa

.0177

.0178

.0160

.0166

.0140

.0120

.W36

Oyg

.0130

.om

.0170

.0168

.0142

. 0M3

.0105

.0080

1