NASA NACA-ACR-4B28-1944 Wind-tunnel investigation of control-surface characteristics XVIII - a linked overhang aerodynamic balance《对操纵面特性18的风洞研究 连接悬垂空气动力天平》.pdf

1、c-. . ._.r%_-(:-.-.-,.,-,;,: ., -,. -.-.=., , -. . , .,.,:.,!?,-)-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-oInx7to remain neutral when the flap was deflected, may be usedas a basis for judging the effect of the various linkedbalances on the l

2、ift curves. As shown by figure 4, thelift and hinge-moment characteristics of the simulatedplain flap changed very little when the gap at the noseof the sealed 0.75cf overhang was filled to form an air-foil of true contour ahead of the hinge axis. The liftcurves for the plain flap are typical of the

3、 lift curvesfor low-drag airfoil sections (references and 6),Figures 4 to 22 indioatie,thatthe linked balanceaffected the lift and hinge-moment characteristics in themanner anticipated, Increments of lift caused by flapdeflections less than 10 were n?arly the same for alllengths of overhang tested r

4、egardless of rate of balancedeflection. The l.CNMf overhang with d6bd6f = 1.00did, however, give a slightly greater increment of liftat bf ?$10 than the plain flap. At Pf E 10,therefore, little air-flow separation presumably occurredover the upper surface of the flap or balance for anyarrangement of

5、 balance tested. .At f 100, the increments of ltft produced byflap deflection were greatly affected by the length andrate of deflection of the balance. For each length ofbalanoe, the lift characteristics at large deflectionsimpboved as the rate of balance deflection with flap de-flection was decreas

6、ed from d6bd5f = 1.00. With the0.75cf and l.OOcf linked balances, for low values ofdObd6f, the lift obtainable throughout the angle-of-attack range for flap deflections greater than 1,0wasequal to and often greater than with the plainflap.With the “0.50cf linked balance, however, the.lift obtain-abl

7、e fon flap deflections greater than 10 was generallynot quite so great as that produced by the plain flap,Unsealing the gap at the nose of the balance wasfound to have an adverse effect on lift characteristicsof the flaps with large overhangs (figs. 15 to 22 andtable I).The data presented in figure

8、23 for the three linkedbalances, the conventional 0.50cf overhang balance(d6bd6f = 1.00), and the plain flap are for a stralght-contour flap and were obtained from the present investi-gation. The data for the conventional 0.35cf overhangProvided by IHSNot for ResaleNo reproduction or networking perm

9、itted without license from IHS-,-,-.8balance were for a cuspedflwp.lzndwere-obtained fromreference b. These data clearly indicate that a flapwith a litied balance is capable of producing muoh higher lift than a flap highly balanced by a conventional over- “hang and slightly higher.lift than an.unbal

10、anced plaintlap. .-. . ., . . qIt,is to be expected that .a0.30c flap with internalbalance capable of giving hge-iuotiqnt characteristics $0comparable with those of the linked balancesof figure could not be deflected more than *20 because of spacelimitation in the balance chamber. The-lift character

11、Istics of such an internally bdan.d flap would thereforebe expected to be the sameas.f. the sealed plain flaplimited to *20 deflection. . .The hinge-moment curves forthe plain flap (fig, 4)are typical of those For low-drag airfoil sections (ref-erences 5 and 6). The rapid change in hinge-moment .co

12、eflioientwith angle of attack at anes of attack nead”the airfoil stall was typical of all balance arrangements tested, The plain and balanced tlaps previously testes on the NACA 6-009 airfoil (figs, 97 to 106 of reference 2) o .had hinge-moment curves similarly affected by air-flowseparation.In the

13、present tests, wth gap unsealemo:t of thehinge-moment curves with the .75cf and 1,00cf overhangsbecame und.esiralynonlinear with change in angle ofatta. The than.gsdueto gap in the variation of hinge-moment with flap deflection was not so great,With some linked-balance arrangements including thatwit

14、h the overhang balance rigidly attached to the flap inorder tk.at C6bdbf = 1.00 and also with the unbalancedplain flapj”a violent oscillation of the flap occurred at .certain anghs of attack at large flap deflections, Allranges in which this oscillation of the flap existed arenoted by dashed lines i

15、n the hinge-moment curves of Zig-ures 4.to 22. The flaps with the linked-balance arrmge-ments th”atgave closely balaiicedhingemoments were .“entirely free from oscillation, A linked balance thusprovides one means of eliminating these flap oscillations.It Is believed that oscillations of the flap cou

16、ldoocur with many conventional blwt-nose overhangs. TheaeProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-9.oscillations have not been evident on models previouslytested in the NACA 4- by 6-foot vertical tunnel becausethe flaps have been restrained in

17、 deflection by a stiff.strain gage; the flap of the present modelwas restrained,ohowever, by only a limber torque rod. Similar oscilla-tions have been noticed.on ailerons tested in the2 LMAL 7- by 10-foot tunnel (reference 7).The hinge-moment characteristics of flaps with twoof the linked balces tes

18、ted are compared in figwe 24on the basis of lift with those of a cusped flap having aconventional 0.35cf overhang (reference 5). A fhp withconventional overhang greater than 0.35cf might have. .given, at low deflections, hinge,moWents more.nearly equivalent to those f klw Iinked.balance but the lift

19、 .atlarge deflections would W 1ss$ thm that for the 0,35cfoverhang. It does not seem probable, therefore, that thevariation of hinge-mbment coefficient with lift coeffi-cient for the linked-balance flap as shown in figure 24can be reproduced by conventional types of aerodjmicbalance on a 0.30c flap.

20、 . .The hinge-moment parameters Cha and ChG for thevarious arrangements of linked balance tested weremeasured at a. =6f= 0 from the curves of figures 4to 22 and plotted in figure 25 as functions of rate ofbalance deflection d6bd5f. The large positive incre-ment in cha with gap is clearly evident fig

21、ure 25.For the 0.75cf balance unsealing the gap did notchange ch .(j . “-,Drag .“ -.At ab,=#Ohe tinim eitheron the ground or in flight. Adjustments can thus easilybe made-to correct undesirable hinge-moment character-istics caused by surface irregularities or-changes-incontour.CONCLUSIONSThe results

22、 of tests of an NACA 66-009 airfoil witha 0.30-airfoil-chord straight-contour flap having variousarrangements of overhang balance linked to deflect moreslowly than the flap indicated the following conclusions:1. A flap with linked balance was capable of pro-ducing as highly balanced hinge moments as

23、 a flap withother types of aerodynamic balance. At the same time,the linked-balance flap was capable of producing slightlyhigher lift than an unbalanced or internally balanced flapof equal ohord and much higher lilt than a flap of equalchord balanced by a conventional overhang.Provided by IHSNot for

24、 ResaleNo reproduction or networking permitted without license from IHS-,-,-“.122. The lift and drag data indicated that increasingthe length of”the flap overhang and causing it to deflectmore slowly to maintain nearly equivalent highly balancedhinge moments tended to delay air-flow separation overt

25、iheflap and balance, especially at large flap deflec-tions. The increase in minimum drag caused.by a largelinked overhang was,the ssme as that caused by a smallblunt-nose overhang of conventional type.3* Both the lift and the hinge-moment character-istics of a control surface with large overhang bal

26、ancewere adversely affected by the presence of a gap at thenose of the balance.4. The hinge-moment characteristics of a controlsurface with a linked overhang could easily be adjustedeither in flight or on the ground by.changing the lengthof a link or a pivot location in the linkage system ofone or m

27、ore spanwise sections of the overhang balanc.Langley Memorial Aeronautical Laboratory,National Adtisory Committee for Aeronautics,Langley Field, Va.“. . . . . - .,. .- . . . %. , . ._.-; .:.-. . . . . . . . . . . . ,. :- - -. : .,:.,.,1,. ,Figure 3.-Oalculatedcharacteristicsof linlmgeSysteqs.Flapdef

28、lection,bf,ldegProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.“Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license f

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31、rovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-L A I I II 1 I I I 1 I I 1 I t t I t I, , , , .1 , ,1 I I t I 1 1 I 1 I 1 I 1 I 11I Ii-lb al/)Ak#?dLKm/7/tlcklWcl-=! U!AD:I$. a71U qq41&Lvjswqd.jzlz“Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-+ I I + I 1 I 1 I t 1 , , t ,.! :, ., I I ! I I I I.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-