1、CnNATIONALADVISORY COMMITTEEFOR AERONAUTICSSOME EFFECTS OFTECHNICAL NOTE 3360PROPELLER OPERATION AND LOCATIONON ABILITY OF A WING WITH PLAIN FLAPS TO DEFLECT PROPELLERSLIPSTREAMS DOWNWARD FOR VERTICAL TAKE -OFFBy John W. Draper and Richard E. KuhnLangley Aeronautical LatiratoryLangley Field, Va.Wash
2、ingtonJanuary 1955Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1A.TECH LIBRARY KAFB, NMI!llilllllllllllllllllll!lllllllliNATIONAL AIXTISORYCOMMITTEE FOR AERONAUKOoabs734TECKNICAL NOTE 3360SOME EFFECTS OF PROPELLER OPERATION AND LQCATIONON ABILITY
3、OF A WING WITH PIAIN ITAPS TO DEFLECT PROPELLERSLIPSTFJMMS IX)WNWARDEOR VERTICAL TAKE-OFFBy John W. Draper and Richard E. KuhnSKMMARYAn investigationhas been conducted to determine the effects ofseveral factors associatedwith the propeller installation on the abilityof a wing with plain flaps to def
4、lect a propeller slipstream downwsrd asa means for achieving vertical take-oft. The factors consideredwerepropeller blade angle, mode of propeller rotation, propeller location,and ratio of wing chord to propeller diameter. The investigationwasmade at zero forwsrd speed on models of semispanwings.Low
5、ering the thrust sxis appreciablybelow the wing-chord planereduced the diving moment of the flaps but had little effect on the turningangle of the slipstream or on the ratio of resultant force to thrust whenthe thrust axis was lowered only 20 percent of the propeller radius. Thebest turning effectiv
6、enesswas obtained when the propeller mode of rota-tion was such that the outboard propeller rotated against the tip vortexand the inbosrd propeller rotated in the opposite direction. On the basisof tests th flat plates of vsrious chords, the best turning angle wasobtained with a ratio of wing chord
7、to yropeller diameter equal to 1.00,which was the lsrgest ratio investigated;however, increasing the ratioof wing chord to propeller diameter from 0.75 to 1.00 led to only a smallimprovement in turning effectivenessbut caused a large Increase h thediving moment.INTRODU7HONAn tivestigation of the eff
8、ectiveness of monoplane wings and flapsin deflect= propeller slipstreams downwsrd is being conducted at theLangley Aeronautical Laboratory. A part of this investigation is reportedin references 1 and 2. The results of reference 1 indicate that a mono-plane wing equipped with plain flaps and auxiliar
9、y vanes can deflect theslipstream through the large angles approaching the angles required forvertical take-off.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACA TN 3360Results are presented herein of a limited investigationof the effects of sev
10、eral variables related to the propeller installationon the turningeffectivenessof the wing with plain flaps at zero forward speed. Thevariables investigated and reported in this paper are as follows: the .propeller blade angle, the mode of propeller rotation, the vertical posi-tion of the thrust sxi
11、s, the longitudinalposition of the propeller disk,and the ratio of wing chord to propeller diameter.sYMEOISThe data presented in this paper are based on the coefficientsgivenbelow and are presented with reference to the conventionof forces,moments, and angles shown in figme 1. It should be noted tha
12、t the coef-ficientswhich are identifiedby the double prime are based on the dynamicpressure in the propeller slipstream as discussed in references 1 and 2.In this manner, the infinite value of the coefficientsat zero forwardspeedCL”%”Cx”Tc”cEDLMis eliminated.lift coefficient, +q“s/2Mpitching-momentc
13、oefficient, q“;Nacelle diameter, ft . . . . . . . . . . . . . . . . O*33Airfoil section . . . . . . . . . . . . . . . . . . . . . .ClwkyThe tests to determine the effects of propellerblade angle and thedirection of propeller rotation were conductedwith two propeller-nacelleassembliesmounted on the t
14、img. A plan and section view of this modelis shown in figure 3. For some tests this model was equipped with twoauxiliary vanes over the hinge line at the b-percent-chord station.Details of the auxiliary-vue configurationare described in reference 1.The tests to determine the effects of propeller loc
15、ation and of the ratioof wing chord to propeller diameter were conductedby use of the setupshown in figure 4. For these tests, a single propeller was located atthe same spanwi.sestation as the inbosrd propeller shown in figure 3.Although the propeller was independentlymounted for these tests, thedir
16、ect propeller forces have been included in the data preseted.A survey of the dynamic pressure in the slipstreamwas also madewith the propeller mounted as shown in figuxe 4. For these tests, thepropeller blades were reversed so as to direct the slipstreamback alongthe motor nacelle and the suppoti me
17、mber. A rake of total-pressuretubeswas mounted on the support to measure the dynamic pressure.The investigationof the effects of the ratio of wing chord to pro- *peller dismeter was conductedwith a series of untapered wings constructedof l/2-inch plywood, with rounded leading edges and trailing edge
18、s that a71were beveled for the rearwsrd l-inch chord. This series of flat-platewings had a -inch semispan and chords of 6, 12, 18, and 24 inches.Each wing was equipped with both -percent-chord and 60-percent-chordplain flaps, and the gaps at the hinge line were sealed for all tests.The tests were co
19、nductedwith the blade-singlesetting at 8.oo.All data presented were obtained at zero forwsrd velocity, a dynamicpressme in the slipstreamequal to 8.o pounds per squ=e foot, and apropeller thrust of 25 pounds. Inasmuch as the tests were conducted understatic conditions in a large room, none of the co
20、rrectionsthat are nor-mally applicableto wind-tunnel investigationswere applied. The pitchingmoments presented are referred to the quarter chord of the mean aero-dynamic chord of the wing. Lift, longitudinalforce, and pitching momentwere measured on a balance at the root of the model. The shaft thru
21、st ofeach propeller was measured by strain gages on the beams supporti theelectric motors inside the nacelles.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 3360 5RESULTS AND DISCIEMIONThe basic data obtained with propeller blade sagles of 3
22、.7 and 8at 0.75 radi for a series of flap settings are presented in figures 5and6. The two propeller blade angles corresponded to the condition of(maximum static-thrust efficiency .75R = 80) and to the condition ofhigh ratio of thrust to torque (.75R= 3“) “ The static-thrusteffi-ciency was determine
23、d by the method of reference 2, which indicated theefficiency of the isolated propeller to be 0.63 for .B.75R= 3.7 and0.70 for .jR= * When the blades were overlapped, the efficiencieswere reduced to 0.57 and 0.65 for j3.75R= 3.70 and , respectively.Effect of praeller blade le.- The effects of blade
24、angle areshown in figuxe 6 Where the 60-percent-chordflap was set at severalfixed deflections and the deflection of the n-percent-chord flap wasvaried. With the 60-percent-chordflap deflected 60, two auxiliaryvanes were added to maintain flow over the airfoil. Figure 6(d) showsthat, for the same thr
25、ust, higher turning angles and generally higherratios of resultsnt force to thrust were obtained with a lower bladeangle. The static-thrustefficiency of the propeller, however, was con-siderably less at the lower blade angle, and in practical applicationthe mount of resultant force that can be obtai
26、ned from a given powerrather than from a given thrust is important. The effects of propellerstatic-thrustefficiency are included in the data presented in figure 6(e).The values presented represent the ratio of force to thrust that wouldbe obtained if the propeller were X20-percent efficient. Figure
27、6(e)presents a comparison of the effects of propeller blade angle on thebasis of conftsmt power and indicatesthat the maximum turning snglesare obtained with the lower blade angle but the maximum resultant forceis obtained with the higher blade angle. It would be destiable, ofcourse, to obtain both
28、maximum turning angle and maximum resultant force.The dynsmic-pressure smveyof the propeller slipstream (fig. 7)indicates that the lower blade angle produces higher velocities near theroot of the blades. It maybe possible that increases in the turningangle can be effected if the propeller could be d
29、esigned to obtain msxi-mun static-thrustefficiency and also to maintain high velocities nearthe root of the blades. In addition, extra care should be taken tomlnbize the possibility of flow separation from the rear part of thenacelles.Effect of mode of propeller rotation.- A comparison of the result
30、sfor two modes of propeller rotation with vsrious flap settings (fig. 8)indicates that, when the outbosrd propeller is rotating against the tipProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 NACATN 3360vortex (right-handrotation on right wing tip)
31、and the inboard propelleris rotating in the opposite direction, higher lift coefficients areobtained. This mode of rotation (also used in refs. 1 and 2) resultsin better turning effectimness than could be obtained with the oppositedirection of rotation, as shown in figixre8(d).TWO factors probably c
32、ontribute to this result: With the outboardpropeller rotating in such a manner as to oppose the tip vortex, the tiplosses are reduced; therefore, the lift would be expected to increase.Also, with this mode of rotation there is an upflow on the part of thewing between the nacelles which produces an i
33、ncrease in lift that prob-ably is not completely csmcelledby the downflow at the wing tip.Effect of longitudinal and vertical position of the propeller.-This phase of the investigationwas made with one propeller mounted infront of the wing with the thmxt axis parallel to the chord plsme ofthe wing (
34、fig. 4). Figure 9 shows the effect of both the vertical andthe longitudinal location of the propeller relative to the wing. Theadvantage of loweri the thrust axis (parallelto the chord plane) isindicated in the pitching-momentdata of figure g(a) where the thrust-axis position z/R of about -0.25 is s
35、ufficientto balance out thepitching moment produced by the flap deflections of bfw = ooand bf60 = no” The turning effectiveness (figs. g(b) and (c) wasvery little affectedby the vertical movement of the thrust sxistithin?cO.20R. At the larger distances from the chord plane the turningangle was decre
36、ased. For values of z/R within tO.20 there was littleeffect of the longitudinalposition x/R on the aerodynamic character-istics of the wing for the two positions investigated.Effect of ratio of wing chord to propeller diameter.- The effect ofthe ratio of wing chord to propeller diameter was investig
37、atedby meansof flat-platewings, as previously described. The results (figs. 10and 11) we presented primarily to determine trends. A direct comparisonof these data in coefficientform with those of the basic model would notbe appropriatebecause of the variations in wing geometry involved; there-fore,
38、the forces and moments for these tests are presented in pounds andfoot-pounds,respectively. The points representativeof the ratios ofwing chord to propeller diameter for the airfoil model are also presentedin these figures in pounds and foot-pounds. The tests were made at zerofrward speed (Tc” = 1.0
39、) with a slipstreamdynamic pressureq = 8.o pounds per squsre foot. The pitchi however, the improvementwas small for an increase.*Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NA.CAm 3360 7. in the ratios of wing chord to propeller diameter from 0.7
40、5 to l.CO.This range of c/D ratio shows low ratios of resultmt force to tlunstand large negative pitching moments.An investigation of someon the ability of a wing witheffects of propeller operation and locationplain sealed flaps to deflect the propellerslipstream through large angles indicate the fo
41、llowi conclusions:1. The best turning effectiveness was obtained when the propellermode of rotation was such that the outbosrd propeller rotated againstthe tip vortex (right-handrotation on right wing tip) and the inbosrdpropeller rotated in the opposite direction.2. Lowering the thrust axis below t
42、he wing-chord plane appreciablyrelieved the pitching moments produced by the flaps; moreover, a verticalposition of the thm.x% sxis within however, the improvementwas small for chord-diameter ratios between 0.75 and 1.00, and lsrge diving moments wereassociated with these larger chord-diameterratios
43、.Langley Aeronautical Laboratory,National Advisory Conmdttee for Aeronautics,Langley Field, Vs., October 8, 1954.REFERENCE1. Kuhn, Richard E., m.d Draper, John W.: m vestigation of aWi%-Propeller Configurationploying Large-Chord Plain Flaps and Large-Diameter Propellers for Low-Speed Flight and Vert
44、ical Take-Off.NACATN 3507, 1954”“ 2. Draper, Joh.nW., andKti, Richmd E.: hvestigation of the AerodyncCharacteristics of a Model Wing-Propeller Combination and of theWing and Propeller Separately at Angles of Attack Up to 90.NACATN 3304, 1954.Provided by IHSNot for ResaleNo reproduction or networking
45、 permitted without license from IHS-,-,-_/L. if) /I Resu/hnf force!Pikhing momentThrust/ Longitudinal force4.d.Figure l.- Sketch of convention used *O define positive 6ense of forces,imments, ad males.CD. . xProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IH
46、S-,-,-. ,I !IIt 425!r 1 .Figure 2j- Plan view of facility used for static-thrust-tests.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10,F 902/ 2/5I-F -LI/7 I-E.18,/67f?o%c ./5I-+272I $,-.4/ 40% cd-lFigure j.- Plan a cross-sectionalviews of mdel. (A
47、ll dimensions in*.inches.)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 33 l-l.A. . . J .-x ., L w,e ;.=_5-. . . . . -. .,.T ,-.- . + .: 3.lLLL.L ._). ,- iL-85693Figure 4.- Static-thrust setup used for tests involving changes inpropeller po
48、sition smd in ratio of wing chord to propeller diameter.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3-2 NACATN 3360cm”./o4?2/.0q“ .500CA” .5do)dego/020304050*.a -20 0 20 40 60F/up deflection, 8f30, deg(a) Pitching-moment,lift, sm.dlongitudinal-force80coefficients. .Figure 5.- Effects of flap deflection on aerodynamic characteristicsofwing in propeller slipstreamat zero forward velocity. Two propellers;Tc”.= l“O; .7X = 370; “ . 8.o pound
