NASA NACA-RM-L7K07-1948 Flight characteristics at low speed of delta-wing models《三角形机翼模型低速时的飞行特性》.pdf

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1、:A aspect ratio _b_Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RMNo. L7KO7 3A sweepback of leading edge, degreesk taper ratio _RTi_ chord_ootc ordkX radius of gyration of model about principal longitudinalaxis of inertia, feetky radius of gy

2、ration of model about principal lateral axisof inertia, feetkZ radius of gyration of model about principal normal axisof inertia, feetp rolling angular velocity, radians per secondp mass density of air, slug per cubic footangle of attack, degreesB angle of sideslip, degrees8e elevon deflection, degr

3、ees, subscripts r and Z denoteright and left elevon deflection, respectivelyT inclination of principal longitudinal axis of inertiarelative to longitudinal body axis, degrees, positivewhen forward end of principal axis is above longitudinalbody axisCL lift coefficient _-_-CD drag coefficient _-_-jCL

4、ater_ force)Cy lateral-force coefficient q$Cm pitching-moment coefficient _Pitching moment_. -)(Rolling moment_C _ rolling-moment coefficient _ _b “J(Yawing mome ntbCn yawing-moment coefficient qSb #Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 N

5、ACA RM No. LTK07CLmax maximum llft coefficient_CZa change of rolling-moment coefficient produced by elevonsas ailerons_Cna change of yawing-moment coefficient produced by elevonsas aileronsCv rate of change of lateral-force coefficient with angle ofIBsideslip in degrees _C rate of change of rolling-

6、moment coefficient with angle of“sideslip in degreesC_ rate of change of yawing-_oment coefficient with angle ofC rate of change of rolling-moment coefficient with rollingvelocity factor in radiansAPPARATUS AND TESTSThe present investigation consisted of tests in the Langley free-flight tunnel, whic

7、h ts described in reference 4, to determine thestability and control characteristics of each of the nine models shownin figures i to 9- The models were simple flying-_Ing models with avertical tall at the trailing edge of the wing but with no fuselage orhorizontal tail. The airfoil used on the wings

8、 was a flat_-platetype,a sketch of which is shown in figure 10. This airfoil was used becauseit was simple to build and because, at low scale, the aerodynamiccharacteristics of delta wings have been found to be virtually independ-ent of the airfoil section. This characteristic was indicated bycompar

9、ison of the delta-_ing data from reference 3 with some unpublishedGerman data on a similar series of delta wings with NACA 0012 profilesand with some unpublished data on a 60 sweptback delta wing with anNACA 0015-64 airfoil.The control surfaces were constant-chord plain flaps at thetrailing edge of

10、the wing. These surfaces were of the type generallyProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM No. LTK07 5called elevons; that is, the two surfaces were deflected up and downtogether to serve as elevators and were deflected differentially

11、 toserve as ailerons.The vertical tails used on the models varied in size but weregeometrically similar having an aspect ratio of 2, taper ratio of 0.5,and no sweep of the 0.5 chord llne. The vertical tail arrangementsused on each of the models are illustrated in figures 1 to 9. Thesearrangements co

12、nsisted of a single tail in the plane of symmetry onall of the models except model 2. This model was the first one testedand used a single tail in the plane of symmetry or two of these tailsat the wing tips which doubled the tail area. Model 2 was the onlyone equipped with a movable rudder.Inasmuch

13、as the present investigation was of an exploratory natureand there was no precedent to indicate what mass characteristics themodels should have, the models were simply ballasted to obtain eitherof the two center-of-gravity positions which were used during the tests.No attempt to adjust the weight or

14、 moments of inertia was made. Themass characteristics of the models, given in figures 1 to 9, weremeasured when the models were ballasted for the rearward of the twocenter-of-gravlty positions which were used during the tests. Thisrearward center-of-gravity position isshown on the figures.Photograph

15、s of two of the models flying in the test section ofthe Langley free-flight tunnel are shown as figur_ ll.Each of the models was flight-tested over as wide a range oflift coefficient as possible with two center-of-gravity positions andwith various vertical tail arrangements in order to determine qua

16、li-tatively the stability and control characteristics and the generalflight behavior. General flight behavior is the term used to describethe over-all flying characteristics of a model and indicates the easewith which the model can be flown, both for straight and level flightand for performance of t

17、he mild maneuvers possible in the Langleyfree-flight tunnel. Any abnormal characteristics of the model aregenerally Judged as unsatisfactory general flight behavior, inasmuchas they are disconcerting to the free-fllght-tunnel pilots._ Ineffect, then, the general flight behavior is much the same as t

18、hepilots opinion or “fee_ of an airplane and indicates whetherstability and controllability are properly proportioned.All the flight tests were made in power-off gliding flight.The range of llft coefficient which could be covered in fllghttestswas limited by the maximum speed of the tunnel which det

19、ermined theloweat possible lift coefficient. The highest lift coefficient wasProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 NACA RM No. L7K07determined by the stall, by maximnm glide angle of the tunnel, or bypoor flying characteristics. The two c

20、enter-of-gravity positionscorresponded to approximately 0.05 and O.10 static mar_in at moderatelift coefficients (CL_ 0.6).Force tests of each of the models were made to determine thestatic stability and control characteristics over the entire speedrange. All of the forces and moments were measured

21、with reference tothe stability axes which are shown in figure 12 and to the rearwardcente_-of-gravity positions which are shown in flg_ares 1 to 9. Thevalues of the stability derivatives CyB, C_, and Cn_ weredetermined from force tests made at angles of yaw of 5 and -5.All the force tests rwere made

22、 at a dynamic pressure of 3.0 pounds persquare foot which gave values of Reynolds number from 402,000to 1,156,000 based on the mean aerodynamic chords of the wings.Tests were made to determine the damplng-in-roll parameter CZpfor models h and 5 by the method described in reference 5_. Thevalues of C

23、Zp for the other models were available and were takenfrom reference 3.RESULTS AND DISCL_SIONInterpretation of ResultsThe results of the force tests of som_ of the wings tested havebeen compared with som_ unpublished data on a delta wing having60 sweepback which was tested in the Langley full-scale t

24、urn,el.The full-scale wing had a sharp leading edge which tended to producethe same. type of flow as that encountered at low scale. Good agree-ment was obtained between the llft, drag, and static stabilitycharacteristics of the low-scale models and the full-scale wing wltha sharp leading edge. The r

25、esults of the present low-scalefllghttests of deltawings, therefore, should give a fairly good indicationof the flight characteristics to be expected of full-scale deltawings having sharp leading edges and si_larmass characteristics.The sharp leading edge on the full-scale wing, incidentally, gavehl

26、ghermax_mnmlift values than were obtained with a round leadingedge. Thus it appears that the free-flight-tunnel models simulatethe more practical case.The effects of changes in the mass characteristics on theflying characteristics of these delta-wlng models were not determined.Some unpublished data

27、from free-fllght-tunnel tests of heavierProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA RM No. LTK07 7delta-wlng models have indicated that increases in wing loading oftwo times and increases in moments of inertia of about four times donot have

28、an appreciable effect on flying characteristics.Presentation of ResultsThe results of the force tests and damping-in-roll tests of thenine models are presented in figures 1 to 9 where all of the measuredaerodynamdc characteristics of a model are presented in the samefigure. These figures are placed

29、in the body of the paper alongwlth the results and discussion so that the complete results (forceand flight) for each model may be presented together. The results ofthe tests are also summarized briefly in table I in order to facili,tate a comparison of the models. _is type of presentation has beenu

30、sed because it appeared that the tests did not cover enough configu-rations to Justify many general conclusions regarding the effects ofsweep and aspect ratio on the flying characteristics of delta wings.Inasmuch as the tests were made with such simplified models, it doesnot appear that predictions

31、of the flying characteristics of full-scale delta-wing airplanes are Justifled at the present time. Noattempt has been made, therefore, to interpret the model results interms of full-scale characteristics.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,

32、-,-8 I_ACA_ No. LTKO7.B,_E_- n.-20-.I i._._ ,5-3 1.6 “lZ _-A/r ,-W -_/ W =2.42 kx “-,5/6(/ _ S =2.67 kr=6.800 S I0 IS 20 25 30 ,9S 40 .I 0 _1 =2 A =3.00 kz=8.08oc Cm X : 0 z :-_.8o _ .zo o O4 .075.OO2 a2o e-_-C_- _ o _J_“-_:_2:004 .-04 _ /er.C;t_l_ .Oa- - I0 -30- - 0 -20t4, .002 -0-.004 ,04.002 ,A-

33、.-_- _ _ (302o o=00_ -.OZ.:=004 ,5 /,5 -.04_.006 .05_ .0_ (de_)(_Z)A I_0 _,.,9 0- o -20.004 -002 ,st/,s-Od_ O 0 .067 4_ %o _o -so.004 I j2Dc _ Al - 0 -40.oo_ ,_ _- _., _-.002 0 , 0 .2 W- .6 .8 I0 12 14 16 0 .2 . ,6 .8 I0 12. 14 16Ca eLFigure 3- Aerodynamic eha_ae_erietlos of model 3-Provided by IHSN

34、ot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACAP$_No. LTKO 7 13Model 3Longitudinal stability and control.-The longitudinal stability and controlcharacteristics of the model were unsatisfactory because of an excessivevariation of static longitudinal stability wi

35、th lift coefficient. Thisvariation is indicated by the pitching-moment data from the force tests whichshow a change in static margin dCm/dC L of about 0.2 over the range of liftcoefficient. When the center of gravity of the model was in the rearwardposition the longitudinal stability was unsatisfact

36、ory at low lift coefficientsbecause of low static longitudinal stability. The static longitudinal stabilityincreased with increasing lift coefficient, however, and the longitudinalstability was satisfactory at moderate and high lift coefficients. When thecenter of gravity was in the forward position

37、 the model had sufficient staticlongitudinal stability at low lift coefficients, but because of the increasein static stability with increasing lift coefficient, the elevens-could nottrim out the large pitching moments at high lift coefficients and could nottrim the model to lift coefficients above

38、a value of about 0.75.In addition to these longitudinal stability and control troubles thevariation of glide angle with lift coefficient caused the same difficultiesas were encountered with model 1. These difficulties are discussed in detailfor model 1.IThe model was not flown at the stall, but the

39、force-test data indicatethat it was statically stable at the stall.Lateral stabilit_ and control.-The model, with either vertical tail,had good lateral stability over the speed range covered in the flight testsCL = 0.21 to 0.83), and the stability of the lateral oscillations appearedto increase with

40、 increasing lift coefficient.The latral control characteristics were good at lift coefficients belowa value of 0.70. At higher lift coefficients, however, the response of themodel to the controls was weak. This weakness might be attributed partly tothe large adverse yawing moments (fig. 3) caused by

41、 the short-span, wide-chordelevens used on this model. The adverse yawing due to elevens and the higheffective dihedral of this model evidently caused large rolling moments whichopposed the eleven rolling moments at high lift coefficients and thus reducedthe rolling effectiveness of the elevens.Gene

42、ral flight behavior.-The general flight behavior of the model wasunsatisfactory because of the excessive variation of static longitudinalstability with lift coefficient. This variation caused the model to haveunsatisfactory longitudinal stability at low lift coefficients when thecenter of gravity wa

43、s in the rearwardposition or caused the elevens to beinadequate for trimming to high lift coefficients when the center of gravitywas in the forward position. Although some intermediate center of gravitymight give satisfactory flight behavior over the entire speed range, thisplan form does not seem t

44、o be practical for tailless airplanes because of thelimited allowable center-of-gravity movement.The lateral flight behavior was good at lift coefficients below 0.70 butwas only fair at higher lift coefficients because of the decrease in theeffectiveness of the lateral controls.Provided by IHSNot fo

45、r ResaleNo reproduction or networking permitted without license from IHS-,-,-14 NACA RM No. L7K07.44.6k i_7.s_.=/ ,_ 25/.61,4g“l IA VV= 2.d._- _x=,2.670 5 /(9 /5 20 2S 30 ,35 40 ./ 0 -/ .2 _ =2.6F #y= _6oC Cm A =a Az=8.86k : 0 _=4.0:2 0-0-0.04 _.02=002 =02o06 0 O_ .0(9 (dec)rn-,0_ 0- 0 -13.00 A . ,I

46、 0 _.0_ - 6 -Iq-_-_T_Dr-“ .1o _ 4_ 4,.to_ (de_)(de-,-m_ 10“ _OZ - O- 0 -2-0o _c_-4_ _ -_l,.S .IO .m /o -3o,0 0 ,06 -_ “1“I 7_ a .IO ,06 i.004- _, _ _ o-0 0 -. OOZ -.02 0 .2 .4 ,6 .8 10 12 14 16 0 .2 .4 .6 .0 10 /2 /At 16ct CLFigure 6.- Aerodynamlo oharaoterlstloeof model 6.Provided by IHSNot for Res

47、aleNo reproduction or networking permitted without license from IHS-,-,-NACA RM No. L7K07 19Model 6Longitudinal stabilit_ and control.-The longitudinal stabilityand control characteristics of the model, with either center-of-gravl_typosition, were fairly good over the speed range covered in the flig

48、httests _(CL = 0.23 to 0.90_. The same difficulties in establishingtrim conditions and flying the model were encountered as wereencountered with model i. The model was not flown at the stall, butthe force-test data show static longitudinal instability at the stall.Lateral stabilit_ and control.-The model had fair lateralstability at lift coefficients below 0.32 wlth either vertical tail.A constant-amplitude rolling oscillation similar to that obtainedwith _Todel 5