1、. _. -t_._,%_,_i_.-_,-, _._ -_ ._- . . # -_-.:_ -_ , _ ._.I_-_ _- :._:“_:_, “-_:_-“-,/_._-_* _,_ / Ik_,/1/ I _/“/“ XI/“ /I/ / / / / /,/“ /./ I8 /2 /6 20ArTgle of a#ock. _, de(?I Ill_e,deCJI_ I I;._:_-_/ /.I.- ./ / I-z_/ -30/“ I i/ III II It II IIiI!11fill24 28 37FlovaI 9.-NormI_-lor_ ecemctent _nst
2、angte of attack at val_ous elevatordeflections for taft surface 9.I/-_ jx/ -_- /f-/./ ?_-/./J/,Fo./,/,/./!/_/ /J/V_f,/V /,I X_/,5./q,/V/_-_/ / /“ “ / I“/ I/II l L_I-8 -4 0 4 8 12 16 20Ancj/e of attack, otr, de_FIGUBg lO.-Normal.force cce_cient against angle of attack at various elevaordeflections fo
3、r tail _urface lO,Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AERODYI_AMIC CHARACTERISTICS OF HORIZONTAL TAIL SURFACES 7.a / / /;s. ., ._/ 17_ -o_ /./_: , i , / /_o / -“7 / /_-.2 / / I1,.“ / 2“/ /-.6 / I“ i/ /-o /-8 -4 0 4 8 12 /6 20Angle of arra
4、ck,_, degFiouRr.I7.-Norma-foreeeoeffeie,t_slnstantrleofattackatvariouselevatordeflections fortaft surface 17.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AERODYNAMIC CHARACTERISTICS OF HORIZONTAL TAIL SURFACES 9Some correlation between experimenta
5、l results andtheory has been attempted. The normal force can beexpressed (reference 4) in the formThe value of k, or dCN/da, depends mainly on theaspect ratio. According to lifting-line theory, thisgations (references 6 and 7) for wings and plates oflow aspect ratio with rounded tips. The observedre
6、ductions in slope, however, somewhat exceed thesepredictions, probably because of the effects of the cut-outs, generally built to accommodate the rudder, andof the gaps between stabilizer and elevator.The effect of the cut-out is strikingly shown by the/.0.8_2/-.6_J/deg /z./?/i/ /“0/II I-_0 -/0 0 I0
7、,T,FJovax I8,-Normal-foree coe_clent q sinst elevator deBect|on atvsrlo_s angles of attack for tall surface 1.1/I0“ _ _ I / F “/ I / /f /I , / /1/. “ s.l _1 I !/ .I / f i“ i/ /“ t1/ iIo / o/ ,t .11/ / ,-i/III I-40 -30 -20 -/0I II-30 -_0 -I0def/ec#/on, Be,Fiaual 19._Normal-fotce coefficientat,atnst e
8、levator deflection at variousangles of attack for tail surface 2.FlOUgl _.-Norm_-foree coefllcicnt against elevatordeflection at vsrlous an Illes of attack for tall surface 3.slope should be approximately ao/(1 57.3ao_+_ . Figure21 shows, however, that the slope decreases much morerapidly with aspec
9、t ratio than does the value of thisexpression. Such behavior has been predicted byPrandtl and by Blenk (reference 5) from theoreticalconsiderations and has been observed in other investi-comparisons in figures 22 and 23. In both cases, theslope of the lift curve was reduced about 2 percent bythe cut
10、-out; whereas, if aspect ratio were the soledetermining factor, the slope would have been increasedby about 4 percent. The net reduction in dC,v,/da,due to the cut-outs, was thus about 6 percent in thesecases.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from I
11、HS-,-,-I0 REPORT NO. 688-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS.08y.02O3 4 5 8 7 8 5Aspecf /of o, AFlOUil 2l.-Variation of the parameter k with aspect ratio and comparison withtheory,.8/.e y , 1Yt_.3 / i- No cut-outcur-our,20 I I“ /;./ /,t/0 /-./ /,/-4 0 4 8 12Angle of offock, _f ,deg/6 2OF;GUa
12、Z 2_.-Effeet of s cut-out on the normal-force eoe_etent of a GSttlnlzen 409airfoil (reference 2),y/-oy- I ./r/the gap tested was narrow and of themost favorable type, being between a rounded concavetrailing edge on the stabilizer and a rounded convexleading edge on the elevator. In the work on flaps
13、reported in reference 8, the effect of the gap was easilymeasurable. The gap tested was a 0.0032 spacebetween a flat trailing edge on the airfoil and a roundedleading edge on the flap. In the flight experimentsreported in reference 9, sealing the gap greatly improvedthe maneuverability and the landi
14、ng characteristics ofthe airplane; the gap, however, was of unusually poordesign, consisting of a 0.02c gap between a roundedconvex trailing edge on the stabilizer and a roundedconvex leading edge on the elevator.The normal-force curves for tail surfaces 2 and 3with and without end plates are shown
15、in figure 24.For the two twin-rudder tails (figs. 2 and 3), the valueof dCs/da, is about 0.074, which is considerably higherthan that for any of the other tail planes. Accordingto the theory of wings with end plates (r_ference 10),dC_ a.ra0X57.3lq ,rAin which r is a factor given by the curve of figu
16、re 25as a function of h/b, the ratio of the height of the endplate to the tail span. For tails 2 and 3, h/b,=0.32 sothat, from figure 25, r=0.63. Considering ao=0.093,it follows from equation (2) that dCn/da,= 0.074, whichis in agreement with the experimental value.The parameter r (equation (1) is t
17、he ratio of theeffectiveness of a change in elevator angle $, to that ofa change in tail angle a,. It is a function mainly ofthe ratio of the elevator area to the total tail areaS,/S,; however, it also depends to some extent on therelative balance area Sb/So, the nature of the gap, andthe plan form.
18、 The experimental values of r for the 17tail surfaces are plotted against So/S, in figure 26.Three different curves have been drawn through thepoints for three different values of S_S,. These curvesapply to tail surfaces in which the gap between theelevator and the stabilizer is open. It appears tha
19、tsealing the gap may increase the value of r by about 1Cpercent. For comparison, the theoretical curve (ref-erence 4) is given.The maximum normal force of the horizontal tailsurfaces is of particular interest for airplanes charac-terized by early center-section stalls or large groundeffects on the d
20、ownwash. For these cases, the flowmay break away on the upper surface of the stabilizerwhen the elevator is deflected upward_ Stalling on thelower surface of the stabilizer, with the elevator de-LO.8.8 I.2.6.5 0 .I ._ .3 .4 .5h“S;FIO_lUB_.-Vsrlatfon of t,_ paramet_ r with the rstio of the height of
21、theend plateto tim ta/l spLu.dCsI I I I Iflop To,/surface Iit“ foil chord v . ,! Z, $1-,_,4.C.A.Z30/Z ._Oc * _ , i 4,5,6/0. o , ,; /0 J- . -.ZO.-. ! ./-4-.ao. _ “ “i tz I.Theoreflcol- - e,. ,;-/3,/,4-(fh_ airfoils; 4 /5,/6, 17r-ef_,et_ce 4J, i I/,/i/7/“I/ .-0,-/a,o0 .Z .4 .6Elevafol- area _Y,Toi/-$u
22、ffoce oleo“ -_FzaUR_“26.-Values of the parameter r for various ratios of elevator area t_ tall sur-face sreLProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-12 REPORT 1_O. 688-NATIONAL ADVISORy COMMITTEE FOR AERONAUTICSflected upward, may possibly occ
23、ur when the airplaneis near the maximum permissible speed with partial-s i Jrail 8urfoce.03E o / t Im, 4 and 5tlO 10 I!x 124 15.18, owdl7 “ “ a Clark Y e/rfoil / twihb plain flops /.020/A/q/oi/0 ./ .2 .3 .4 .5 ._Elevator oreo ,_Tail-surfoce oreo _-FXOOLt _.-Variat/on of 4Cx,14_. with the rst/o ot el
24、evator ares to ta/l-surf_lSrel.8.4.2JO-.6-301 lToil _-fcc-eo 4o 5o 6/ /J-_0 -I0 0 I0 20 30Elevafcw clef/cobon, _, .deqFLOUR= 28.-Increment of maximum normal-force eoemoient against elevator deflec-tion for tails with offset-hinge balance.span flaps fully deflected. This particular flight con-dition
25、may occur when an airplane is waved off duringan attempted landing on an aircraft carrier or takes offimmediately after landing with flaps down. It ismost desirable that the elevator effectiveness be main-rained at the stall. Values of dC_,=/d_, taken be-tween elevator deflections of 10 and - 10 , a
26、re plottedagainst So/S, in figure 27, together with similar data foro SUF OCR-Oo J/j/“/r/SJJj,l_ _lO 0 lO 20E/evo_or deflection, 8o , deqF1OURI 29,-Increment of maximum normal-force coefficient against elevator deflec-tion for tails with overhung balance.plain flaps on the Clark Y airfoil. The value
27、s of themaximum normal-force coe_cients are given for mostof the tail surfaces in figures 1 to 17.The considerable scatter cf the points in figure 27may be attributed to the many factors upon which themaximum force depends. One important variable isprobably the section thickness; thus, in the analog
28、ous_.253_ F-_ . : _:._ _Flouaz 30.-Diagram showing elevator in deflected position on ta/l surfaces 4, 5.and 6.case of flapped airless, the flap effectiveness has beenshown (reference 8) to increase with thickness.The gap between the elevator and the stabilizer isalso an important variable. Results o
29、btained withflapped wings showed that the increment of maximumlift due to deflecting 0.20c flaps is reduced 20 to 30percent by a gap of only 0.003c between a convex lead-ing edge on the flap and a flat trailing edge on the airfoil(reference 8).Provided by IHSNot for ResaleNo reproduction or networki
30、ng permitted without license from IHS-,-,-AERODYNAMICCHARACTERISTICSOF HORIZONTALTAIL SURFACE8 13Comparison of the results for tall surfaces 4, 5, and6 (fig. 28) and for tail surfaces 7, 8, and 9 (fig. 29) showsthe effect of elevator balance on the elevator effective-ness at maximum normal force. Fo
31、r the largest offset-hinge balance (fig. 28), the elevator effectiveness beginsto decrease after about 10 deflection, and increasingthe deflection beyond 20 has little effect. The discon-tinuity in the surface caused by the protrusion of thebalance (shown in fig. 30) probably induces the stall inthi
32、s case: For the overhang, or horn, type of balance(fig. 29), the effectiveness of the elevator is maintainedup to 30. deflection. The rate of increase of the maxi-mum normal force with elevator deflection is lower,however, than for the offset-hinge balance.The range of Reynolds Numbers over which th
33、e datafor elevator effectiveness are valid is unknown. Flaptests made in the N. A. C. A. 7- by 10-foot and variable-density wind tunnels (references 8 and 11) indicate,however, that the increment of maximum lift due toflap deflection is not greatly affected by the ReynoldsNumber.ELEVATOR HINGE MOMEN
34、TSThe hinge-moment coefficients are plotted againstelevator deflection in figures 31 to 46 for different valuesof angle of attack of the tail surface. No hinge mo-ments were measured for tail surface 1. The curvesare smoothest, in general, for unstalled conditions andfor elevators without balances.
35、Increasing either a,or L into the stalled range is generally accompanied bya marked variation, usually a sharp increase, in thehinge moment.The theoretical hinge-moment coefficients for thinairfoils are derived in reference 4 for elevators withoutbalance. They are expressed in the formC_.=uC_+v_. (3
36、)and theoretical curves are given for u and v as functionsof the ratio eJc,. The theoretical values of u derivedfrom thin-airfoil theory, however, are somewhat higherthan the theoretical values corresponding to airfoils offinite thickness. Thus, hinge-moment calculations forc,/,-0.3, based on the th
37、eoretical pressure distribu-tions for the N. A. C. k. 0006 and N. A. C. k. 0018 air-foil sections, gave values for u abo0t 0.89 and 0.73,respectively, of those given by thin-airfoil theory.In the present analysis, experimental values for u andv were found from the curves of figures 31 to 46. Thus/_c
38、/ac_. /_c,AThese experimental values, for tail surfaces withoutbalanced elevators, are plotted against SJS, in figures47 and 48, which also show the theoretical curves fromreference 4. The values of u fall considerably belowthe theoretical curve but the values of v are in fairagreement with the theo
39、ry. The gap between theelevator and the stabilizer as well as the nonuniformdistribution of c./c, across the span of the tail doubtlesscontributes to the scatter of the points on figures 47and 48.Reduction of hinge moments by shifting the hingeback along the elevator (offset-hinge balance) is illus-
40、trated by tail surfaces 4, 5, and 6 (fig. 49). Theeffectiveness of the overhang type of balance in reduc-ing hinge moments is shown in figures 37 and 38.The flight experiments of reference 9 showed that, byclosing the gap between the elevator and the stabilizer,the tail effectiveness was increased a
41、nd the stick forceswere much reduced. The gap in the case tested, how-ever, was unusually wide.DRAGSeveral plots of drag coefficient Co against ac aregiven in figures 50 to 54. They exhibit the usualparabolic increase with angle of attack and the sharprise after the angle of stall; however, the incr
42、ease in allcases considerably exceeds that corresponding to theusual induced-drag equation, C_ -CL2-_-_. This largerdrag is attributed to the large tip losses of the surfacesof low aspect ratio.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-14 REPOR
43、T NO. 688-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS-.I,.24./6._ .080.24./6108-.Id“-.24I _o I I I! _ “ i I lI _. _ I- (_)-(b)-ll! 0/0_30IIt-“II,IIIIItLI Ii-28 -24 -20 -/6 -/2 -8 -4 0 4 8 12 16Elevator de,elect/on, 6e, degt! II,lIilI1ItII1_IIIIIII1I-t-LII20 2_ 28(a) FloU_z 31.-Taft sur- (b) Flou_c 3
44、9.-Tail sur- (c) FZG_.Z 33.-Tail sur-face 2 face 3. face 4.Elevator h_lllg_-moment coefficient against elevator deflection at various angles of attack for tail surfaces:2, 3, and 4.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-15AERODYNAMIC CHARACT
45、ERISTICS OF HORIZONTAL TAIL SURFACES24-.24.161_-.08-.16-.3P.08-,/-(b) -1-/6 -/B -8 -4 O 4 8 /2 16 20E/evafor“ deflech_. 6e .(:leg(a) FIouRz 34.-Tail sur- (b) Ft_t, iz 35.-Tai! sur- (c) Ftr, t_Rz 38.-Tai! sur-face 5. faoe 8. face 7.Elevator hinge-moment coefficient against elevator deflection at vari
46、ous angles of attack for tail surfaces 5, 6, and 7.222647_40-3-2 -24 -20_24.24 _ _ _- (c)- _ _ 1_ “_“24 =)8Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-16 REPORT NO. 688-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS-24 -L_O -/6 -M .8 -4 0 4 8 12 16
47、20 24Etevofor“ de?lecfion, _ ,deg(a) FlOURZ 37.-Ta|l sur (b) Floullc 38.-Tail sur- (c) FKOURZ 30.-Tail sur-face 8. face 9. face 10.Elevator hlnge-moment coefficient agaiust elevator deflection at various angles of attack for tall surfaces 8, 9, and I0.Provided by IHSNot for ResaleNo reproduction or
48、networking permitted without license from IHS-,-,-AERODYNAMIC CHARACTERISTICS OF HORIZONTAL TAIL SURFACES 17.24./6.08-./6t- (a -III II-_ I I i ,._-.24-32,Z4./6_. .08_o08- -(b) “L_ I-L./6 “_“_ “_ i _0 7“- _!_ _._-_ t_,deg-_ _ oi-?-._sji_ -“_5“ I-.06- c)-li, It-28 -24l-20 -16 -12II-8 -4 0 4 B 12 /8 20 24Elevalor deflecf/on,6,.deg(a) FIGU.12.08.
