1、REPORT 941PREDICTION OF THE EFFECTS OF PROPELLER OPERATION ON THE STATIC LONGITUDINALSTABILITY OF SINGLE-ENGINE TRACTOR MONOPLANES WITH FLAPS RETRACTEDBy JOSEPHiVEILand WILLIAMC. SLEmLW,Jr.SUMMARYThe effects of propeller operation cm the static longitudinalstability of ti”ngle-engine tractor monopla
2、nes are analyzed,and a simple method is presented for computing power-onpitching-moment curres for $ap-retracted jlight conditions.The methods erolred are based on the results of powered-modelwind-tunnel inrestigatiom+ of 28 model configurations. Cor-relation curres are presented from which the ejlx
3、ts of power onthe douvumsh orer the tail and the stabilizer effecticenem canbe rapidly predicted. Tle procedures dereloped enable pre-diction of power-on longitudinal stability characterietiea thatare generally in rery good agreement ur”th experiment.INTRODUCTIONThe prediction of the el%3ct9of prope
4、ller operation on thestatic Iongitudimd stability and controI characteristics ofsingle-engine tractor airpIanes has been the object of manyinvestigations. Successful methods have been dewlopedfor estimating the direct propeller forces and the effects ofslipstream on the wing-fuselage characteristics
5、 (references 1to 4). Attempts to predict the compIex changes in flowat the tail pkne, however, have been somewhat Iess success-ful, primariIy because many of the eady researchers werehindered by insufficient. experimenhd data for developingmethods of proved general applicability.During the war years
6、 an appreciable amount of experi-mental data pertaining to power effects on static longi-tudinal stability -was obtained. An analysis of these datasuggested the possibilities of a semiempiricrd approach tothe probIem of determining the effects of power on the taiIcontribution to stability. This appr
7、oach has been folIowedin the present report and a simple, rapid method for deter-mining the effects of power on the tail contribution ispresented. Use of the procedures deveIoped permit theaccurate prediction of power-on longitudinal stability andtrim characteristics. No anaIysis has been made for t
8、heflapdeflected condition.SYMBOLSc. lift coefficientc. pitching-moment coefficientCmac aerage section pitching-moment coefficient aboutaerodynamic center for wing section immersed tislipstreamthrustcoeflkient (Thrust/pV17)thrust coefficient corresponding to power-off liftcoefficientincrement of thru
9、st coefficient from power-off con-dition to a specified power conditionairspeed, feet per secondFIir dem=ity, slugs per cubic footpropdler disk area, square feet-area of wing or tail, square feetspan of wing or tad, feetpropeIIer-blade section chord, feetpropelIer diameter, feetpropeIIer radius, fee
10、tradius to any propeIIer bIade element, feetviing mean aerodpmmic chord, feetwing root chord at plane of symmet, feetwing chord at break for wings hav compusitepIan forms, feet chord at theoretical tip, feet%0 chord at spanwise station 0.50R or 0.75R fromairplane center line, feetviing aspect ratiow
11、ing taper ratio (cJc, for wings having linear taper)distance from reference center of gratity to thrustIine measured perpendicular to thrust line (posi-tive when e.g. is above thrust line), feetdistance from reference center of grm-ity to propellercenter line measured paraIIel to thrust line, feetdi
12、stance from reference center of gravity to elevatorhinge line, feetdistance from eIevator hinge line to thrust linemeasured perpendicular to thrust line (positivewhen eIevator hinge Line is above thrust line, feetangIe of attack, radians unless otherwise denotedpropeller blade angle, degreesstabiliz
13、er setting with r=pect to thrust line (positivevihen traiIing edge is down), degreeseIemtor setting with respect to chord Iine of stabiker(positive when trailing edge is down), degreeseffective angle of dommvash at horizontal taiI, degreesincrement of povier+ff dow-mvash at horizontal tailfrom zero
14、lift down-wash, degreespower-off downwash angIe at zero lift399Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-REPORT 941NATIONAL ADVISORYCOMMITTEEFOR AERONAUTICS400cpti derivative ofrwpect toradiansCY$O vake of CyI$propeller normal-force coefllcient
15、 witha.e of inclination of thrust line. infor T,=OS.F.F. abbreviation for propeIIer side-force factorf ratio of i?ytti to Cyl#fo ratio of Cy#$for power-off value of Te to Cy,+0F empiricaI taper-ratio factorR, dCm()ratio of power-on stabilizer effectiveness -dt, ,dm()ta power-off stabilizer effective
16、ness R, dCmratio of power-on elevator effectiveness ()m. ,()dCto power-off elevator effectiveness 60A change in a quantity due to powerSubscripts :TetPPowMithrust lineelevatorhorizontal tailpropellerpower onpower offwingwing-fuselage combinationimmersed in slipstreamBASIS OF ANALYSISThe method of co
17、mputing power-on pitching moments,which is outlined herek, is b figures 3 (a) and 4 (a) are for Iow-speed propellers having thick, cambered blades; figures 3 (b)and 4 (b) are for high-speed propellers having thin, wideblades; plan-form curves of propellers on which figures 3and 4 are based may be fo
18、und in figure 4 of rcfcrcnco 1,The term ck/da, the upwash factor, is obtained from figure 5.Slipstream effect on wing-fuselage characteristics,. -Thomethod most widely used for computing the increase in winglift due to the slipstream is given by SmcIt and Davies inreference 3. This method required s
19、everal succcssivo approx-imations, however, to obtain final power-on lift cocffwicntswhen T. varies with CL. An approximtite formula has I.)ccndeveloped which is shorter than that of rcfcrencc 3 and whichrequires onIy a single estimation to obtain t.hc find value ofACLM;thus an appreciable amount of
20、 computing time issaved. This equation is given by(3)where c= is the wing chord at spanwisc station 0.75R fromairplane center line for wings behind single rotating propcllcmor 0.501? for wings behind dual rotating propellers.Thrus t-=oe fficien t, TcFKWEE2.Varlntionoffwlth 7%Provided by IHSNot for R
21、esaleNo reproduction or networking permitted without license from IHS-,-,-PREDICTION OF PROPELLER EFFECTS ON STATIC LONGITUDINAL SABIL OF SINGLE-ENGJNE MONOPIANS b(s)Ha.miltnn Handard 316S-6Fopdkrwkh O.lWdinmew sPInneGS.F.F.- but the chief effect is probably caused by the aheredwing span load distri
22、bution brought about by the passageof the prope.Uer slipstream over the wing. Although appre-ciable downwash may exist behind an ie.dated propeller atan angle of atta however, d was believed to b a moresignificant factor than a for use in the correlation inasmuchas a71 depends on tail location and u
23、sually varies Iinearly witha up to fairly high lift coefficients. The assumption wasmade that a tail well out of tho power+ff maximum down-wash fieId wouId also be favorably bcated in the power-ondown-wash field for configurations within the range ofgeometry of the models presented.Provided by IHSNo
24、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-PREDICTION OF PROPELLER EFFECTS ON STATIC LONGITUllINAL SABILITY OF SINGLE-ENGINE MONOPL4XES 4072.01.61.2/-,:SKETCHA plot
25、 of the parameter (AT.)d against the experimentalAe obtained from stabilizer and tad-off wind-tunnel data for28 model conrations is show-n in figure 9 (a). The dash-line cur-ma in the e indicate the approximate accuracyProvided by IHSNot for ResaleNo reproduction or networking permitted without lice
26、nse from IHS-,-,-408 REPORT 94INATIONAL AINTSORY COMMITTEE FOR AERONAUTICS.28Curve ciSiSdm detemin oionof equdkm - ,.- -.242 / Model1938. iVood,Donald H.: Tests of Nacelle-propeller CombhlatIons InVarious Positions with Reference to Wmge. Part I. ThickWing-N. A.C.A. CowIcd Nacelle-Tractor Propollcr.
27、 NACARep. 415, 1932.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-PREDICTION OF PROPELLEB EFFECTS ON STATIC LONGITUDINAL STABILITY OF SINGLE-ENGINE MONOPIAN13S 415Provided by IHSNot for ResaleNo reproduction or networking permitted without license
28、from IHS-,-,-416 REPORT 941NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS 1 Test , CcmpufedI I I I I 1 I IIo(c) Comparison of comfmtd and esrnentfd etleots of poweronthe neutti pcdntsmd tail.CMe.wcdynamic-canter 10CMOUFIGGRE14.Caneluded.TABLE 1.GEOMETRIC CHARAOTERISTIH OF MODEL “COIGURATIONS USED IN CR
29、RELATIONShim aer w rmt wgregkModelNACA airfoilseone%!% %:p %kwrWingroot Wingbrink WingtiI-I mt o,4- . .1 P.462 7.a9.40 L810 1.2S3 -7.61 1.210 0.242L02fl m 2-21f3 -.242 66,2-216 :+.842 b666!lo1.021 .464. . . .416.s4 L ml ;%!23016 k; .a2!z3B2H 6.34 :2L 021 .! M (L6W L 021 .4P4: 6.24 230161.69323016L 0
30、21 IA#Ill2m14=7Ly% 7.66 L2XI 1.6752aL a767.4s9 L 360.6s3 2416 4412 6.26 .4126L m . -1.WI.mo 2216 - 5.91 .4462m924 :2 ;Z.-. .SmL 1% W -m6 -.nl6.91 .445(m%wf). . . 6.50 .W26 la 18 a4m(modfiled)2024 - L 047(rlP(ft)center ofgraetifytibhingennq It-a096-095-.w.095-.095.005.oas.IYJ5.w-.Iw5.m-.180-.0s6-.W.m
31、.w.W6-.066.004.053-.Io3.059.om.072i%.016.W6.-.TsS hefghtabove thrnstlfnc dt(d)Ia71 Pkehfng-moment eoeftkfents W on same Z. and model pvot kstfoo 88 fw mtxieIs l Cr,-Olfl (EG s (s). Sbme S33.-65.S hr model 21, . 4 (a)k ud tooormctCrJt,.Rii1$?khdgqPiC“pLW58L 10381.lmbL !2329L 24376L304JIL46b7n$w0.0918
32、.0344.o!b32.m31.0301-.0378-.oa22g$gg0:$40b. 645.s.7381.98111,18771.6574$=z-a OLm-.1306-.1741-.2120. 24!32-42$86-.8320iiigam4m4114nnTABLE 111.RANGE OF GEOMETRIC-CHARACTERISTICSOF MODELS INCLUDED IN CORRELATION*Gcometrio peremeterWIn.gtwpcft ratfo I 5.17(mel I OM*CKMN)IWfng taper Lutio I 027b(model19)
33、 I 1.M(mrdc 171 IPmpellerdiemekW!rlg mm I 0.217(mdel 24) I 0.354(modelXJ) IHefghtoftsUabovethrust Unepropellerdiemeter 0.042 (mwlel 11) 0.418(model 15) ITeilmenWhlg Spsn I 0.322(model 19) I 0.623(mod(d 3) ITa.UlenhMean oerodynemk chordHeightofthroetline above wing mot cbonlPrweller dlemeter -SE=Dlstenw of propeller ehesd of wing rcmt ohordRoot ehurd I 0.490(mcdel 18)I0.206(model X)IProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
