NASA NACA-TN-2775-1952 Effect of linear spanwise variations of twist and circular-arc camber on low-speed static stability rolling and yawing characteristics of a 45 degree sweptba《扭曲.pdf

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1、NATIONALADVISORY COMMITTEEFOR AERONAUTICSTECENICAL NOTE 2775EFFECT OF LINEAR SPANWISE VARIATIONS OF TWISTAND CIRCULAR-ARC CAMBER ON LOW-SPEED STATIC STABILY,ROLLING, AND YAWING CKARACTERHTICS OF A 45 SWEPTBACKWING OF ASPECT RATIO 4 AND TAPER RATIO 0.6By Byron M. JaquetLangley Aeronautical Laboratory

2、Langley Field, Va.WashingtonAugust 1952TECI-HWCM WWARYAFL 2811.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NMIllllllllllllllllllilllll:llllll011b58b7lU.PNATIONAL ADVISORY COMMITTEE FOR AJ?J?ONAUTICSTECRNICAL NOTE 2775EFFECT OF

3、LINEAR SPANWISE VARIATIONS OF TWISTAND CIRCULAR-ARC CAMBER ON LOW-SPEED STATIC STABILITY,ROLHNG, AND YAWING CHARACTERISTICS OF A 45 SWEPTBACKWING OF ASPECT RATIO 4 ANDTAPER RATIO 0.6By Byron M. Jaquet .suMMARYAn investigation at law scale has been made in the Langley stil-ity tunnel in order to dete

4、rmine the effect of linear spanwise varia-tions of twist smd circular-arc caniberon the low-speed aerodynamicchsracteristics and static-stability and rotary-stability (rolling andyawing) derivatives of a wing of aspect ratio 4, taper ratio O.6, andwith 45 sweepback of the quarter-chord line.Results

5、of the investigation indicate that twist or camber pro-duced only small changes in the maximum lift coefficient. A combinationof csnber and twist was nmre effective than twist alone in providingan increase in the maximum lift-to-drag ratio in the mderate lift-coefficient range for the ngsinvestigate

6、d. The variation of staticlongitudinal stability through the lift-coefficient range was less forthe twisted wing than for the twisted end caniberedor plane wing.A combination of twist and csmibergenerally extended the initiallinesr range of several of ths static- and rotary-stability derivativesto a

7、 higher ld.ftcoefficient and, although these effects were small,higher Remolds numbers may result in larger effects.INTRODUCTIONOne of the disadvantages encountered.in the use of sweptback wingsis the premature stall of the tip region which causes the variations ofthe aerodynamic parameters to depar

8、t from their initial linear trends atlow angles of attack (refs. 1 and 2). These nonlinearities often leadto difficulty in dynsmic stability. Twist, caniber,or a combination ofthe two is sometimes incorporated in swept wings in order to provide aProvided by IHSNot for ResaleNo reproduction or networ

9、king permitted without license from IHS-,-,-more satisfactory spanwise load distribution. These factors would also “be expected to extend the initial linear range of those parametersdependent primarily on the spanwise load distribution of the wing tohigher angles of attack. nThe effect of linear sps

10、nwise viations of twist and a combinationof twist and circular-arc camber on the low-speed static-stability androtary-stabilityderivatives (rolling end yawing) of a wing with45 sweepback of the quarter-chord line, an aspect ratio of 4, and ataper ratio of 0.6 were determined in this investigation. A

11、n indicationof the effect of camber was attained by a comparison of the data for thetwisted wing with that for the twisted and cambered wings. Also includedwas the determination of the effect of leading-edge roughness on the.aerodynamic characteristics of the wings at zero angle of sideslip.The pres

12、ent investigation is a part of a research program beingmade in the Langley stability tunnel in order to determine the effectof various geometric parameters on the static- and rotary-stabilityderivatives of wings and airplane configurations.SYMBOISThe system of stability axes, with the origin at the

13、projection ofthe quarter-chordpoint of the mean aerodynamic chord on the plane ofsynnnetry,is used throughout the paper. The positive directions of theforces, moments, and angular displacements are shown in figure 1. The vsymbols and coefficientsused herein are defined as follows:A aspect ratio, b2/

14、S .b wing span, fts wing area, sq ftc local chord parallel to plane of symmetry, ftr/2mean aerodynamic chord, so c2dy, ftCr root chord, ftCt tip chord, ftx taper ratio, ct/crProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3CLCDCy. cm.spanwise distanc

15、e measured from, andof symmetry, ftperpendicular to, plaqeangle of attack of root-chord line, degangle of twist about -percent-chord line, measured withrespect to root-chord line and in a plane parallel to planeof symmetry, deg; positive when trailing edge is downcamber angle, angle between chord li

16、nemean camber line at 75-percent-chordeffective twist sngle, G + 6, degand line tangent topoint, degangle of sweepback of qusrter-chord line, degangle of sideslip, degsngle of yaw, degfree-stream velocity, fpsmass density of air, slugs/cu ftyawing angular velocity, radians/seerolling angular velocit

17、y, radians/seelateral flight-path curvature, radianswing-tip helix angle, radianslift coefficient, P$sdrag coefficient, Q-+s2lateral-force coefficient, *.AEJ+Mpitching-moment coefficient, $V%Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 NACATN 27

18、75cl rolling-momentCn yawing-momentD drag, lbcoefficient, *Pap3 mNcoefficient, Pav SbY lateral force, lbM pitching moment, ft-lbL rolling moment, ft-lbN yawing moment, ft-lbL/D ratio of lift to dragacnCnp =aflacyCy =P apacnCnp .#Jhow-ever, at moderate and high lift coefficients, twist increased the

19、dragconsiderably. Addition of 3 of ca?riberto the twisted wing almostcanceled this increase.Wing 3 had the highest value of L/D (fig. 6), whereas wing 2 hadonly a slightly higher”valueof L/D than the plane wing (wing 1).Wing 3 maintained a value of L/D higher thsn that of the other wingsthroughout t

20、he moderate lift-coefficientrange.CL2 ffigo 6) h= frequentlyA rapid rise in the expression CD-=,been used as an indication of the lift coefficient at which separationeffects become evident and, thus, the slopes of curves of derivativessre likely to change.a rapid rise in CD -wing.A small increase in

21、 the lift coefficient whereCL2 occurs was noted for the twisted and camberedXAPitching-moment characteristics.-Twist caused a large positiveincrement in the pitching-nmment coefficient (due to a forward andinboard movement of the center of pressure) through nnst of the lift-.coefficient range, where

22、as csmber, as indicated by a comparison ofwings 2 and 3, caused a negative increment (due to a rearward and out-board movement of the center of pressure) which was large at low lift.coefficients and decreased as the Lift coefficient icreased (fig. 5).The variation of stability through the lift-coeff

23、icient range was lessfor the twisted wing than for the plane or twisted and cambered wing.Effect of transition strips.- A comparison of figures 5, 6, 7, and 8shows that fixing the transition at the leading edge of the wing decreasedthe maximum lift coefficient smd the msximum value of L/D and caused

24、 anincrease in the value of CD at low lift coefficients. The maximum liftcoefficient of wings 2 and 3 was more sensitive to the roughness along theleading edge; this fact indicates that these wings might be more sensi-tive to an increase in Reynolds number.Fixing transition at the wing leading edge

25、caused a forward movementof the aerodynamic center for each wing, as is evident from the change inslope of Cm plotted against CL. (Compare figs. 5 and 7.)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 NACA TN 2775Static Lateral Stability Character

26、isticsTwist and camber had insignificanteffects on the variation of CyBad CnB with CL (fig. 9).The variation of CtP with CL (fig. 9,)for the plane wing islinear up to about the sane lift coefficient as that at which there isCL2a rapid rise in CD - with increase in CL (fig. 6). Incorporating a linear

27、 twist variation had little effect on the linesr range of thece of CZP plotted against CLO Combining camber with twist extendsthe linear range of the curve by about CL = 0.10. It should be notedthat the test Reynolds number was low (0.895 x l and that perhapsgreater effects of twist or caniberwould

28、be realized at higher Reynoldsnumbers.Twist and camber had essentiallyno effect on the value of CZBat 10W lift coefficients. The addition of camber to the twisted wingcaused a large increase in ths value cl at moderate and high liftBcoefficients;hence, it was indicated thatthecamber in wing 3 caused

29、the load near the tips to be retained at higher angles of attack than forwings 1 or 2. The increments in CIP in the moderate lift-coefficientrange due to twist or camber are larger than the increments caused byadding one of several vertical tails to a wing-fuselage combinationa71having the same wing

30、 as wing 1. (See ref.,5=).a71Figure 10 is included to illustratethe variation of Cy, Cn)and Cz with for angles of sideslip greater than those (p = *50)used to determine Cy , Cn and CIP.PP The lift coefficients for eachwing are different for a given angle of attack.Rolling CharacteristicsTwist or a c

31、ombination of twist and caniberproduced only minorchanges in the values of Cyp, Cnp) and “Cl at low and high liftPcoefficientsbut produced large changes in these derivatives at moderatelift coefficients (fig. 11) where the flow over the wings is changingfrom potential to separated flow. The small ef

32、fects of twist and camberon Cnp at low lift coefficients may be significantwith regard to the .lateral dynamic stability of an airplane. A combination of twist.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-u NACATN 2775.and camber extended the init

33、ial linear range of CYP and C%“w linear range of these derivatives isgenerally smaller than thatc2by the curves of CD - (fig. 6) or the linear range of Clp,Theindicatedprob-ably as a result of a higher angle of attack on the descending tip ofthe rolling wing. Camber increased the damping in roll sli

34、ghtly at lowlift coefficients but caused a rapid decrease at about CL = 0.25, whichcan be associated with the decrease in C% that .occu at approximatelythe same lift coefficient. (See fig. 5.) At high lift coefficients,camber increased the damping in roll.The increments in the rolling derivatives at

35、 rnderate lift coef-ficients due to twist or camber sre considerably larger than the incre-ments caused by the addition of any one of several vertical tails to awing-fuselage combination having the same wing as wing 1. (See ref. 6.)Yawing CharacteristicsTwist and camber produced changes in the yawin

36、g derivatives(fig. 1.2)unlike those produced in the rolling derivatives (fig. 11).Twist or camber produced lsrge changes in the rolling derivatives onlyat moderate llft coefficients,whereas, for yawing derivatives, twistor camber produced essentially constant increments in the yawing deriva-. tives

37、throughout the lift-coefficient range.The changes in cYr caused by twist or camber are probably insignif-.icant when the dynamic stability of an airplane is being considered; how-ever, the changes in Cnr and Clr due to twist or camber maybe signif-icant. The increments in Czr due to twist or camber

38、in the nnderatelift-coefficientrange are greater than the increments produced by addingsny one of several vertical tails to a wing-fuselage combination havingawing the same as wing 1 (ref. 7). Neither twist nor camber extendedthe linear part of the curve of Czr plotted against CL; however, athigher

39、Reynolds numbers, twist or cmiber,effects on the linear part of the curve.CONCLUSIONSor both, might have larger. An investigation at low scale made in the Ia.ngleystability tunnelto detepnine the effect of linear spanwise variations OZ twist andcircular-arc camber on the low-speed aerodynamic charac

40、teristics and.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NACATN 2775static- end rotary-stabilityderivatives of a wing with 45 sweepback of .the quarter-chord line, an aspect ratio of 4, and a taper ratio of 0.6led to the following conclusions

41、:v1. Twist or csmber produced only small changes in the maximum liftcoefficient. A conibinationof csmber and”twist was more effective thantwist alone in providing an increase in the maximum lift-to-dragratioin the moderate lift-coefficientrange.2. The variation of static longitudinal stability throu

42、gh the lift-coefficient range was less for the twisted wing than for the plane wingor the twisted and cambered wing.3. A combination of twist and camber generally extended the initiallinear range of several of the static- and rotary-stability derivativesto a higher lift coefficient and, although the

43、se effects were rathersmall, higher Reyholds numbers may result in larger effects.Langley Aeronautical Laboratory,National Advisory Committee for Aeronautics,Langley Field, Vs., June 18, 1952.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN277

44、5 11. REFmmxs. 1. Cempbell, John P., and Goodman,Estimating the Rolling MomentTN 1984, 1949.2. Toll, Thomas A., snd Queijo, M.Alex: A Semiempirical Method forDue to Yawing of Airplanes. NACAJ.: Approximate Relations and Chartsfor Low-Speed-Stability Derivatives of Swept Wings. NACA TN 1581,1948a71 .

45、3. MacLachlan, Robert, and Letko, William: Correlation of Two Experi-mental Methods of Determining the Rolling Characteristics of UnsweptWings. NACA4. Bird, John D.,Fuselage anda Swept-WingTN 1309, 1947.Jaquet, Byron M., and Cowan, John W.: Effect ofTail Surfaces on W-Speed Yawing Characteristics of

46、Model as Determined in Curved-Flow Test Section ofLsngley Stability Tunnel. NACA TN 2483, 1951. (Supersedes NACAm L8G13.) .5. eijo, M. J., and Wolhart, Walter D.: Experimental Investigation ofthe Effect of Vertical-Tail Size and Length and of Fuselage Shapeand Length on the Static Lateral Stability

47、Characteristics of aModel With 45 Sweptback Wing and Tail Surfaces. NACA Rep. 1049,1951. (Supersedes”NACATli2168.). 6. Wolhe,rt,Walter D.: Influence of Wing and Fuselage on the Vertical-Tail Contribution to the Low-Speed Rolling Derivatives of MidwingAirplane Models With 45 Sweptback Surfaces. NACA

48、TN 2%7, 19517. Letko, William: Effect of Vertical-Tail Area and Length on the YawingStability Characteristics of a Model Having a 45 Sweptback Wing.NACATN 2358, 1951.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-T#BLllImm aETIom ormmAT22CA 65AOJ8 thickn.a dlstritmtti_. q+ Y.M.281SJ1.W51.68432.=502.8133.3753.938;:%37.62s:%-r.3137.m8.h389.009.$3Io.mlo.6ea11.aI LE. rd. -,=a3y, in.161.loa.095.0020.046 in.-0.360.04Tlp c1winex b.l.om1.361.702.ob2.382.723,063,bo3,744,024.b2;:E%6.EJ6M6.20rd of=a 2y, h.“LRoof sectionCumben?dtIp sec