NASA NACA-TN-3307-1954 An investigation of a wing-propeller configuration employing large-chord plain flaps and large-diameter propellers for low-speed flight and vertical take-off.pdf

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1、I-NATIONALADVISORY COMMITTEEFOR AERONAUTICSTECHNICAL NOTE 3307AN INVESTIGATION OF A WING-PROPELLER CONFIGURAONEMPLOYING LARGE -CHORD PLAIN FLAPS AND LARGE -DLAMETER PROPELLERS FORLOW-SPEED FLIGHT ANDVERTICAL TAKE -OFFBy Richard E. Kuhn and John W. DraperLangley Aeronautical LaboratoryLangley Field,

2、Va.WashingtonDecemtir 1954AFMDCProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECHLIBRARYKAFB,NMNATIONAL ADVISORY COMMITTEE FOR AERONAUTICS I!lllllllllllllulllilul!llIIOLL304TECHNICAL NOTE 3307AN INVESTIGATIONOF A WING-PROPELLER CONFIGURATIONEMPLOYI

3、NG LARGE-CHORD PLAIN FLAPS ANDLARGEDLMETER PROPELLERS FORLOW-SPEED FLIGHT ANDVERTICAL TAKE-OFFBy Richard E. Kuhn and John W. DraperSLMMARYAn investigationof the effactiveness of a wing equipped with lsrge-. chord plain flaps and auxilisry vanes in rotating the thrust vector oftwo large-diameterprope

4、llers through the large angles required for ver-tical take-off and low-speed flight has been conducted in the Langley.300 MPH7- by 10-foot tunnel. The semispan model used was equipped witha 60-percent-chord flap, a -percent-chord flap, and two large-diameteroverlapping propellers.Under static-thrust

5、 conditions, a maximum upward rotation of theeffective thrust vector of 450 was obtained with the 60-percent-chordflap deflected no and the -percent-chord flap deflected no. Withthe addition of two auxiliary vanes, the upward deflection of the thrustvector was increased to 6P. With this configuratio

6、n,vertical take-offcould be made with a take-off attitude of 23 and at airplane weights upto 95 percent of the thrust. A method is presented for calculating thelift due to flap deflection and slipstream for small flap deflectionsif the lift due to flap deflection at zero thrust and the lift due tofl

7、ap deflection at zero forwsrd speed are known.INTRODUt!TIONThe practical utilization of the helicopter has indicated the use-fulness of aircraft that are capable of operating from very small bases.The advantages to be gained with aircraft that incorporate the small-.field capabilities of the helicop

8、ter and the high-speed potential ofconventional airplanes we readily apparent. Numerous designs have beenproposed for achieving these advantages If lift is to be produced, Itis necessary to give amass of air per unit time a downward velocity.!.!,IProvided by IHSNot for ResaleNo reproduction or netwo

9、rking permitted without license from IHS-,-,-2The helicopter uses a large rotor to deflect a largetime downward at a relatively low velocity; however,having the rotor axis approximatelyPerpendicular toNACATN 3307mass of air per unit .the consequenceofthe flight path .-seriously limits the high-speed

10、 potential of the helicopter. uReference 1 reports satisfactoryflight tests of a configurationwith which hovering and vertical landings and take-offs were made possibleby turning the slipstreamof relatively lsrge-diemeterpropellers down- .-ward by means of a cascade of vanes. The configurationwas de

11、signedsolely to demonstrate the feasibilityof this approach and to study thestability and control problems in hovering and in vertical take-off andlanding. No provision was msde for forward flight.The present i.nvk?stigationwas undertaken to determine the effective-ness of a monoplane wing equipped

12、with plain flaps for deflecting theslipstreamthrough large angles and thereby providing appreciable liftat low forward speeds. The effectivenessof auxiliary vanes, in combina-tion with the plain flaps, h deflection of the slipstreamthrough thelarge turning angles required for vertical take-off was a

13、lso investigated.When aand moments.COEFTICIENTSAND SYMWLS.wing is located in the slipstreamof a propeller, large forcescan be produced even,though the free-stream velocity decreasesto zero. For this condition, coefficientsbased on the free-stream dynamicpressure approach infinity and therefore becom

14、e meaningless. It appearsappropriate,therefore, to base the coefficientson the dynemic pressurein the slipstream. The coefficientsbased on this principle are indicated “-in the present paper by the use of a double prime snd are defined in thissection. The positive sense of the forces,.moments,and an

15、gles determinedfor the static-thrusttests is shown in figure 1. For the tests at for-ward speeds, the usual convention for forces-was used; that is, the liftand longitudinalforce were taken perpendicular and parallel, respectively,to the free stream.CL liftL1l liftcm”coefficientbased onLcoefficient,

16、 - “q“s/2Lfree-streamdynsmic pressure, qs/2pitching-moment coefficient, it- moment .q“eS/2%P”Propeller pitching moment *propeller pitching-moment coefficient,q“sF .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 3307 3cNp” propeer normal-forc

17、e coefficient, Propeller normal force. q“swTc“Abc. dDhL“Nqq“rlongitudinal-forcecoefficient, Witutid forceTthrust coefficient, - D2“ :aspect ratiowing spau, ft; also, propeller bladewing chord, ft(3s/2chord, ftgfb/2mean aerodynamic chord, so c2dy, ftslipstream diameter at leading edge of wing, f%prop

18、eller tiameter, ftpropeller-blade thickness, ftlift, lbnumber of propellerspvzfree-stream dynamic pressure, lb/sq ft2Tdynamic pressure in slipstream, q + lb/sq ft $4radius to propeller blade element, ftradius to propeller tip, ftProvided by IHSNot for ResaleNo reproduction or networking permitted wi

19、thout license from IHS-,-,-4sTvAVwYaP$.75RafeEE“Ptwice semispan-wingarea, sq ftthrust per propeller,free-streamvelocity,incrementof velocityairplanespanwiseangle ofweight, lb.distqnce fromattack, degpropeller-bladepropeller-bladeangle,lbPt/Bec!.nslipstream.wing rootdegNACATN 3507.“due to thrustangle

20、 at 0.75 radius, degflap deflection, deginclinationof resultant force vector at zero forward speed,arc tan Q -is 0.8x 106.-.aerodynamic a71.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NA.CATN 3307 7In order to minimize the time required for the t

21、ests, the operatingconditionswere chosen so that only two propeller blade-sngle settingswere required. A blade angle of however, they have been applied throughout the entire angle-of-attack range. The lift coefficient for the power-off condition wasused in correcting all data.Corrections to the free

22、-stream dynsmic pressure for the effects ofthe model blockage have not been applied in reduc the data. Thesecorrections are negligible in the low angle-of-attackrange but becomeof increasing importance as the drag increases at the higher am.glesofattack and higher flap deflections. The correction ca

23、n be estimated bythe method of reference 4 and applied as follows:( 0.036 1qcorrected= %easured 1+ - !%“ - c” Cos a (0”613)cIProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 NACA TN 3307REDUCTION OF DATA “The data obtained in this investigationwould

24、 be applicable to thetype of flight operation illustrated in figure 8. A flight of this typebinvolves zero forward speed for tske-off and landlng, where the generatedlifi is obtained from the thrust of the propellers. In this flight COI-Pdition, the use of free-streem dynamic pressure in reducing th

25、e data tocoefficient form would result in extremely high coefficientsas the free-streem dynsmic pressure is reduced to low values. At zero forwsrd speed,the coefficientswould always be infinite and therefore meaningless. Forthe condttion in which the wing is largely immersed in the slipstream ofa pr

26、opeller, the forces would be expected to be largely determined by thedynamic pressure in the slipstream. It appears appropriate, therefore,to base the coefficientson the dynsmic pressure in the slipstream. Withthis system the coefficientsapproach their normal value as the speed isincreased and Qso h

27、ave a finite value at zero forward speed. The thrustcoefficient Tc”to unity at zeroThe .MMiCpropellerwhere %incrementpeller atthrustapproaches zero as the speed is increased and is equalforward speed.pressure in the slipstreen can be computed from the .by the simple momentum theory as follows:is the

28、 mass flow through the propeller and AVO is theof velocity due to thrust at a great distance behind the pro-zero angle of attack. The terms can be rearranged as follows:(AVG0)2 T2 +VAVGO -= oZD24Solvlng by the quadratic equation yields.Provided by IHSNot for ResaleNo reproduction or networking permi

29、tted without license from IHS-,-,-NACA TN 3307.sBy deftiition, t! Tr,i-L Some other useful relationshipsThe abovehave been=-+“;:can be expressed as:= 1 - Tc”Tc“(1)(2) ,(3)(4)relations have been derived forapplied to the data through thean angle of attack of 0 butangle-of-attackrange.The results of t

30、hefigures:RESULTS AND DISCUSSIONinvestigation are presentedt Static thrust conditions:Plain-flap configurations ; . . . . . . . . . . .Auxiliary-vane configuration . . . . . . . . . in the followingFigures. . . . . . . 9-1o. . . . . . 1.1-12Provided by IHSNot for ResaleNo reproduction or networking

31、permitted without license from IHS-,-,-10 NACA TN 33Q7Figures .Tests with forwsrd speed:Two propellers operating30-percent-chordflap . . . . . . . . . . . . . . . . . . . .s13-18- and 64)-percent-chordflaps . . . . . . . . . . . . . . . 19-22 _. ._.Inboard propeller operati (30-percent-chordflap) .

32、. . . . . 23-26Effect of flap deflection and thrust coefficientonlift characteristics . . . . . . . . . . . . . . . . . . . . 27-28I *V+(V+AV)sti e“term represents the Uft due to deflecting the mass ofthe propeller slipstreams and the second term representsdeflecting the slipstreams themselves. For

33、small anglesof downwash sin E“ = d d in coefficient form .57*3. where d is thew In terms ofpropeller slipstream dismeter at the wing (ref. 2).tltethrust coefficient,L JAt Tc” = O,%tan=2 CLwhere CR is the induced-dreg coefficientDi = 2AFor small angles, then,given by*E = 2(5+a71Provided by IHSNot for

34、 ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 3307ac2(7.3)ae a5f=a5f fillAt Tc“ = 1.0 and small flap deflections,he“= however,have no consistent effect on the normal-forceProvided by IHSNot for ResaleNo reproduction or networking permitted without license from I

35、HS-,-,-16coefficient.far ahead ofThe propellers ofthe wing where theNACATN 3307the test model were located relatively 8upwash due to the wing would be small.The operation of the propeller in the presence of the wing is seen 4almost to double the pitching moment of the propeller as comparedwiththat o

36、f the isolatedpropeller (fig. 30).Deflection of the flaps pro-duces a further increase in the propeller pitching moment.-.Theseincreases cannot be attributed to an increase in wing-induced upwashat the propeller disk because an increase in upwash should produce corre- .spending increases in propelle

37、r normal force. It is probable that theseincreases in pitching moment are due to a change h tk velocity throughthe upper and lower portions (relativeto the wing-chord plane) of thepropeller,disk. An increase in velocity over the wing (upperpart of thepropeller disk) would tend to decrease the thrust

38、 from the upper part of.the disk. Conversely, a decrease in veloci through the lower half ofthe disk would increase the thrust of this part of the propeller, whichresults in an increase In the nose-up pitching moment of the propellerwith increasing angle of attack and with increasing flap deflection

39、. The propeller pitching mcment can be regarded as an effective dis- aplacement of the thrust of the propeller axis. The effective locationof the thrust vector is presented in figure 31 and was determined fromthe pitching-momentdata of figure 30 by the following relationship: 9cl illustrate the appl

40、ication of the.data and to permi% a %rethorough analysis of the results. A wing loading W/S of 40 pounds persquare foot and a drag coefficientof 0.01 for the fuselage and otherparts of the airplane not representedby the model were assumed. Theflight plan was assumed to start with the auxiliary vanes

41、 extended and(flaps deflected 30 = 2 and *60 = 600 for vertical take-off at an)aikplane attitude of 23 (dataof fig. 11). The airplane attitude wasthen reduced to a lower angle, for example 50, after which the vanes,the 60-percent-chordflap, and the 30-percent-chordflap were retracted,in that order.P

42、rovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACAliftm 3307The thrust coefficient required for zero longitudinalcoefficient available for various flap configurations“17force and thewere determinedby cross-plottingthe longitudinal force and lift coe

43、fficients againstti.rustcoefficient as in figure 32. The forward velocities,associatedwith these conditions are calculatedby the expressionThe thrustplotted againstcoefficient required and lift coefficient available areforward speed in figure 33. Unfortunatx?ly,the failureof one of the blades in the

44、 outboard propeller terminated the test hthe tunnel before the tests of the auxiliary-vane configuration at theintermediatethrust coefficients could be performed.The performance of the present configuration, in which the propellerthrust is used for vertical take-off by deflecting the slipstream down

45、-ward with the w- and vanes, is compared in figures 33 to 35 with theperformance of the configuration of reference 2 in which the entire wingand propeller are rotated from vertical for take-off to horizontal forcruising flight. The present configuration requires somewhat lowerthrust coefficients and

46、 lower thrust horsepower for level flight at lowforward speeds (figs. 33 and ). The power required was calculatedlythe method of reference 2. The power required for take-off is somewhathigher for the present configurationbecause of the losses associatedwith turning the slipstream downward. These los

47、ses do not appear exces-sive, however, and can probably be reduced in a more efficient design.For either configuration, if a high-speed propeller efficiency of 0.85and a static thrust efficiency of 0.65 is assumed, there wi be suffi-cient power available for take-off if the airplane is designed for

48、aspeed of the order of 400 mph.The pitching moments that would have to be balancedby some auxiliarymeans are presented in figure 35, along .th the corresponding effectivemoment armof the center of lift “/”. The diving ments associatedwith the present configuration are appreciably larger than the nose-upmoments for the configuration of reference 2. Also, at zero forwardspeed, the present configurationhas a large diving moment while thepitching mment for the configuration of reference 2 wo