1、REPORT No. 658TESTS OF TWO FULL-SCALE PROPELLERS WITH DIFFERENT PITCH DISTRIBUTIONS,AT BLADE ANGLES UP TO 60By DAVID BIRM.iM and EDTIN P. HARTMANSUMMARYho S-blade 10oot propellers were operated in jiontoj a liquid-cooled en”nenacelle. Tite propellers diferedonly in p“tch distribution; one had normal
2、 distribution(nearly constant p“tchfor a blade angle of 16 at 0.76radius), and the other had the pitch of the tip ectionsdecreasedwith respect to that for the shank sections (bladeangle of 36 for nearly constant pitch distrz”butior,). Pro-peller bladeangles at 0.75Rjrona 16 to 60, correspondingto de
3、sign speeds up to 600 miles per hour, were investi-gated.The results indicated that the propultice eficieney at ablade angle of 60 was about 9 percent less tha:nthe mati-muna aalue of 86 percent, which occurred at a blade angleof aboui 30. Tle ejiciency at a blade angle of 60 wasincreased about 7 pe
4、rcent by correctingfor the eect of asp”nner and, at a blade angle of 30, about $3percent.T7Mpeak efitiencieg for the propeller huuing the uxzshed-out pitch distm”butionwere slightly lesg than for the normalpropeller but the take-of ejhiency was generally higher.INTRODUCTIONTests of full-scale propek
5、-s made at the X. . only the results for the two extreme pitch dia-tributiona tith the liquid-cooled engine nacelle aretherefore reported.In tiew of the fact that propeller spinners are verybeneficial for high-speed airplanes equipped withliquid-cooled engine nacehs, the results of the testaof the p
6、ropelk with the standard pitch distributionat a blade angle of 15 are ako given for the spinnercondition.827Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-328 REPORT NQ. 656-NATIONAL. ADVISORY CCWMITTEEFQR AERONAUTICSAPPARATUS AND METHODSThe propell
7、er-research tunnel has been modifiedsince the description of reference 2 was written to theextent of installing an electric.motor to drive the tunnelpropeller and. of replacing te balance. with a moremodern one capable of R radfusto the tip; r, stationmdtus;b, ssct!onchord; b,swtlon thfck-nw II, gso
8、rnetrlopitch.and a comparison of the pitch distributions is given infigure 5.The method of testing in the propeller-research tun-nel consists in maintaining the propeller speed constantand increasing the tunne speed in steps up to thomaxurn value of 115 miles per hour. Higher valuesof lnD are obtain
9、ed by reducing the engine speeduntil zero thrust is reached. The tests were run at tipspeeds of 525 feet per second and k to avoid com-plications arising from compressibility. The standardinitial testing propeller speed of 1,000 r. p. m. couldnot be maintained for the higher blade-angle settingsProv
10、ided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TWO FULL-SCALE PROPELLERS WITH - - - -.1JIJflMlffiN1 YlUtl JJMLIU.B lJ1lW.Nt3 329owing to the limitation of engine power. The follow-ing schedule was adhered h:Propeller apeeti for tunnelspeed below 116 mil
11、es per hourBladeangle(de%) lnKhim,e,d mdedeayle ,MCr(yymg apecd15 1,000 40 70020 1,000 45 70025 8CK) 50 65020 800 55 60035 800 60 560For _linD values higher than can be obtained fromthe foregoing schedule, the approximate t-t propeIIerspeed may be computed from t,herelationr. p. m. =Fydwhere K= 1,00
12、0 for T7=115 miles per hour and D= 10feet.An analysis of results from tests with the spinner forpropeller blade angles of 15,25, and 35 indicated thatthe effect of the spinner could be trardated into a dragvalue independent of the blade angle (5.5 pounds at100 miIes per hour). The rewdts without the
13、 spinnerwere consequently corrected for the effect of the spinnerby the formulaAC,= O.OO1O75(V/nD)2instead of making additional tests with the spinner.Any erroreincidental to this process are considered to bewithin the experimental error. This formtia appliesonly to the conditions of the present tes
14、ts.The spinner was regarded as a part of the body; thereduction in drag of 5.5 pounds at 100 miks per hourwas therefore primarily due to enclosing the hubportions of the propeller.RESULTS AND DISCUSSIONThe results are reduced to the usual coefficients ofthrust., power, and propulsive ef6ciency defin
15、ed aseffective thrust TADc= D, Dengine povrer0.= ,Dc. vV=c. mwhereT, tension in propeller shaft, pounds.AD, change in body drag due to slipstream, pounds.p,mass density of the air, slugs per cubic foot.nj propeller speed, r. p. s.D, propeer chneter, feet.l“, air speed, feet per second.Charts for sel
16、ecting or designing propellers are givenin the form of C, against and V/nD,Lines of constant thrust coefficient have been super-posed on the power-coedlicient curves to facilitatethrust computations at alI air speeds for tied-pitch andcontrollable propellers. For an outline of the methods,see refere
17、nce 3.The test results are given in the form of charts infigures 6 to 17. These results have aIso been tabulatedPr/RFmmE t +0 .2 .4 .8 .8 LO /.2 L4 1.6 L8 2.0 EL? 2.4 2,6 2,8 3.0 3.2 3,4 38 3.8 4,o 4.2 4,4 4.6V/nDFmrmBL5.-ThrusGooeflMent ctmes for propeller 6SS9 wfth nplnnw. CNwCJlProvided by IHSNot
18、 for ResaleNo reproduction or networking permitted without license from IHS-,-,-coCua.68.64.60.56.52.48.44.40.36G.32,28.24,20.16.12.08.040 ridz,oFmuBB 16.-PowoLmt cxmremfor propaks LWE?-9wltb nne8.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TWO F
19、ULL-SCALE PROPELLERS WITH DIFFERENT PITCH DISTRIBUTIONS 3375.0.8v.4 40uwvG2.0/.(7Q /.o .20 3!0 4.0 50 beyond thisvalue there is a small loss. The reasons for this condi-tion are apparent in figures 19.and 20, wherein a comp-arison is made of the propeller characteristics for threeeffective pitch-dia
20、meter ratios for zero thrust. It maybe noted that propeller 5868X2 does not stall so soonwith increasing angle of attack (decreasing V/nD) asdoes propeller 5868-9, which accounts for the gain ineficiency. The efficiency ccmrputed for the take-offcriterion is taken at a value of_V/nD of one-fourth th
21、atfor hh speed. l?ropeIIer 5868-X, consequently has ahigher take-off efficiency for conditions where theV/nD for stall coinoides with the takeoff criterionV/nD wd has a lower efficiency when the vahws do notcoincide. The delayed and abrupt stalling character-istic noted for propeller 5868-X2 is evid
22、entiy due tothe fact that more of the bade elements stall at thesame time than for propeller 58689.Limitations and application of the test data,In viewof the fact that the present tests were run at relativelylow tip and twmel speeds, the effect of comprcesibility,which enters the problem at higher s
23、peeds, should notbe fcygotten. It is pointed out in rcferencc 5 thatcorrections to the propeller chara.cterist.icsfor tho take-off condition shouId be made for tip spec_dsabove about0.5 the speed of sound.-Eadier tests (reference 6) had indicated that noappreciable loss in efficiency was evident at
24、tip speedsbelow about 0.9 the speed of sound for the high-speedcondimon. Later evidence shows that this value appliesonly to forward speeds up to 200 or 300 miles per hour.Figure 21 is a plot of the true speeds of each propellersection for a true tip speed of 1,000 feet per second(approximately 0.9
25、the speed of sound at sea level) nndfor dithrent flight speeds. The curve of the sectionspeeds corresponding h the compressibility stall wassomputed from airfoil data given in references 7 and 8md from other high-speed airfoil data not published.An arbitrary correction for thee-dimensional flow wasD
26、ade for the tip sections to bring the airfoil and tho?ropach ropellw seciknI I I I IJ? ffor dferenf fligh speeds-Computed secfion speed Of fhecompressibility sfull for see-level flighf700 II 1 1)m Ctark Y-f Hp;e v/5& . / fm / / +, /e /q 400 /GMO . / /3 1/ /$ 300 f /J 300 /$ / a, Arbitrary correcfimf
27、or ihree-dimensiona/flow of fhe fip200/m/ao,o .2 .4 .6 .8 Jor/RFmrmx 21.Curve9 showing true W* of propsller 6wtforu for a tfp * of MOOf. p. m and dlffarent flfght spealx aho comrmtadwtkm SW* at the eompres4-blllty stall.CONCLUSIONSThe propulsive d3hiency at a blade angle of 60 vm.sabout 9 percent Im
28、s than the maximum value of 86percent, which occsurredat a blade angle of about 30.The efficiency at a blade angIe of 60 was incrmeedabout 7 peroent by correcting for the effect of a spinnerand at a blade angle of 30, about 3 percent.An attempt to improve the propulsive efficiency ofpropellers set a
29、t high blade angles by reducing thegeometric pitch of the tip sections with respect to theshank sections (namely, increasing the blade gle fornearly oonstant pitch distribution from 15 to 35)resulted in a small loss in the bigh+peed efficiency and again in the take-off efficiency for low blade angle
30、s.The blade-angle range covered in this report isapplicable to flight conditions up to about 500 milesper hour at sea level and about 425 miles per hour at35,OOOfeet, provided that comprwsibility effeots at theblade tips and shanks do not become critical.LANGLEY MEMORIAL AERONAUTICAL LABORATORY,NATI
31、ONAL JbVISORY COMMImnEFOR AERONAUTICS,LANGLEY FIELD, VA., April IJ, 1838.,-1“i.rue&ee& of &OLJlkr iechbk I1- Cmnpuied sechon kped fII .compressibifify sfuli t+o .2 .4 .6 .8 I.orjlfFIOUESZ2.-Bladeaectlon aPeaIs owraspa!dfng to hkh+-p=d opsratfon at “ bkxleangle, and cmnpated serdfrm crItfml spead9 fo
32、z dh.lamnt althxdw. ProLarSSS-9 with apInner.1.2.3.4.6.6.7.8.REFERENCESLesley, E. P., and Reid, Elliott G.: Tests of Five MetalModel Propellers with Varioue Pitch Distributions in a FreeWiid Stream and in Combination with a Model VE-7FuasIage. T. R. No. 326, N. A. C.& 1929.Weiuk, Fred E., and Wood,
33、Donald H.: The Twenty-FootPropeller Research TunneI of the National Advisory Clmm-mittee for Aeronautic. T. R. No. 800, N. A. C. A., 192%Biermann, David, and Hartman, Edwin P.: Tests of FiveFull-Scale Propellers in the Prwmnce of a Radial and aLiquid-Cooled Engine NacelIer Including Tsats of Two Spi
34、n-ners. T. R. No. 642, N. A. C. A., 1938.Anon.: Comparison of Wind Tunnel Tests with Flight Testson a Number of Detachable Blade Propellers Made from. .the same PIan Form. A. C. I. C., vol. VII, No. 632 (A. C!.T. R. No. 2943), 1920.Biermann, David, and Hartman, Edwin P.: The Effect ofComprwibiLity o
35、n Eight Full-scale Propellem Operating inthe Take-Off and Climbing Range. T. R. No. 639, N. A.C. A., 1938.Wood, Donald H.: FuU-Scale” Tests of Metal Propellers atHigh Tip Speeds. T. It. No. 375, N. A. C. A., 1931.Stack, John: The N. A. C. A. HighSpeed Wind Tunnel andTeds of Six Propeller Sections. T. R. No. 463, N. A. C. A.,1933.Lindsey, W. F.: Dmg of Cylinders of Simple Shapes. T. R.No. 619, N. A. C. , 1933.!2691424%23Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
