1、,.COMMITIEE FORL“- 290( ,._-.:,”,-Glqd $n thetunel in order that force-test measurements of lift, drag,and pitching mmant may be made. The hinge moments ofboth flaps”were measured with eletrically indicatiw,cantilever-b, wirestrain gages.The 2-foot-chord by.+foot-span mode (fig! 1) wasmade of lamina
2、ted mahogany to the NACA 0009 airfoil con- htour. t!h forward and rearward flaps were alo built ofmahogany end their- respective chords were 20 perceqt ofthe airfoil chord (0.20c) and 15 percent of the airfot -chord (0015c), The 0.0050 gaps btween the airfoil andthe forward f14p and betweqn the $orw
3、ard and th,. . -. f. . .y. :,. ,., .-%.-,1”.:,.,.“;“., - . . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-,-. -3-. flaps were sealed with grease f-or some tests and wereleft open for others, TESTSThe NACA 0009 airfoil with the 0.20c forward flapa
4、nd the 0.15c rearward flap! when mounted in the tunnelscompletely spanned the test section. With this type oftest installation, two-dimensional flow is approximatedand the section characteristics of the model may be de- “termied. The model was attached to the balance frameby torque tu-oes that exten
5、ded through the sides of theturmel. The angle of attack was set from outside thetunne by rotating the trque tules with “an electricdrive. Defections of each flap were qet insidq the tun-nel by templets and were held by friction “c3amps.The tests were made at a Qneuic preesure of 15 poundsper square
6、foot, which corresponds to a velocity of about76 miles per hour. I-heeffeotive Reynolds number of the -tests was approximately .2,760,000. (Effective Reynoldsnumber = test eynoid number X turbulence factor. Theturoulence factor for the NcA 4- oy Ct .airfoil section lift coefficient (z/qc)Cdo airfoil
7、 sectio profile-drag coefficient (do/qc)cm airfoil section pitchivgwmowent coefficient (m/qca)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. -.- .-+ - A.- -7 -L,- =. ,fi.k, - - -._. A, . . . . . . ,.-.- -,-,. . . . . . . . . . . .,. *:” ,., . . .
8、. . .,.,. . . . . . .forward-flap section hinge-moment, coefficient (hl/qc48) ,forward-flap eection binge-moment coeffic.iet (hl/qca)rearwa.rd-f.lap sactio hinge-moment coefficient (h8/qcaa)rearward-flap s.stio hiqga-oment coefficient (he/qc8)control-stick fog pE3.) Zt$qge-momerit coefficient(E. . +
9、 : -.,. .,., . . . . . . .+ .-. . ,J- . . WN. ”?-:.=% -, . . .,. . .:, . . . ,. .,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-68 deflection of an aerodynamically equivalent tiingle-flap control surface having a deflection equal tothat of the con
10、trol stick. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. ._ ._. .-. . - - -36The subscriptsoutside theparameters tidicatethe factorsmeasurement of the parsmed%rs.parentheses around theheld constant during theT“ similar characteristicsof the air
11、foilwith the r%zward flap sealed and neutral for variousdeflections of the unsealed and sealed forward flap arepressnied in figure 6. Figures 7and 8 show comparisoncumes of the lift available from given flap deflectionsand of the stick hinge moment required to produco givenlift izmremen-tsfor O.50c,
12、O.30c,O.20c, O.15cplainflaps and for severel arre.ngomentsof double plain flaps.Comparisons similarto those of figwes 7 and 8 are givenQ tables 1 and II in tho form of the variom lift andh+mment yerameiers, wlch are cplicabiO ovOr onlya small ren of U and 5. A comp.miacn of the dmgdaracterist:c5 of
13、the various singlm and double flqp atem an-.e.- u! e.! - , , . . . . -. . - . . . .+,.- -.-+-+;. ,.,. .;-“:“- .;:)ou tha data presented in rs:erence 7. 1:.9L ifteffetivonec of both flnps decrease.dw-aerit-he gep a.tthenose wa3 unseale, Tie fortvad flap showed a c.till frrtherdecrease in “l”lft”effec
14、tiveness but the rearward flap dtdnet vben ooth gaps were cpen. The effe”ctivenese of aGoubie-flap combination K,tiybe expressed in ters of theffetieness of each fla P.nd the relatie rates of de-f19ct5c)G. Thu S-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license fr
15、om IHS-,-,-* ;.“.8“.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-9“angle of attack, all flaps of this group produce aloutthe same positive lift. A 0.15c single flap producesconsiderably more lift when deflected positively 60 atzero and positive an
16、gles of attack than does a 0,30c flapdeflected 30. At a large negative angle of attack, theQ.30c flap roduces greaterlift.H3nge MomentsThe test points for the.flap hinge-moment coefficientsplotted in figur,es 3 to 5 are in some cases somewhat errati-cally dispersed about the faired curves. A large p
17、art ofthis dispersion was caused by continued improper function-ing of the electrical strain-gage units that were used inmeasuring the hinge gwments. In fairing the curves some ofthe test points beliaved to be in error have been disre-garded. It was not considered north the time and the effortrequir
18、ed to check eah doubtful hinge-moment test pointbecause, for this investigation, lift rather than hinge-moment characteristics were of primary importance. Thehinge-moment curves of figure 3(e) for ba = 200 and of,figure 3(f) for 62 = 25d appear to be in error, althoughthe tes,ts were repsated throug
19、hout the angle-of-attackrange. Jt is lelieved that the data presented adequatelydefine the hinge-moment characteristics of the unbalancedflaps tested. .The hinge moments of the 0.20c and the 0.15c flapschange very little with angle of attack for low flap de-flections; hence, these small-chord flaps
20、have very littlefloating tendency. At large positive deflections, thahinge moments change rapidly froin a large negative valueat zero and positive lifts to almost zero at large negativelifts. This rapid change of hinge-moment coefficient oc-curs ia the same lift range and at the same large flapdefle
21、ctions for which the slope of the lift curve ctbecomes excessively steep. Whether the hinge-momentcoefficient will reach a sufficiently large positive valueat large, stalled, negative angles of attack to give rudderlock remains a subject for further investigation. Thesedata indicate that, at the neg
22、ative stall, the hinge-momentcoefficient for all positive deflections is nearly zero?Even if the control surface should blow over at the stall,therefore, little force would be required to bring thecontrol back to zero deflection.Provided by IHSNot for ResaleNo reproduction or networking permitted wi
23、thout license from IHS-,-,-. .10The-hinge-moment slopes measured at small anglea oattack and at small ciefleotions are presented in table Ifor various gap conditions. The slopes cha and chfor the flaps with sealed gaps are in close agreement withthos-e predicted from the parameters presented in refe
24、rence7. The slopes given in table I can be used to estimatereletive characteristics of double-flap control systemsof the tpe considered. In dealing With the hinge moments”of double-flap systemst it is convenient to compute thestick hinge monent, which in effect is the hinge moment ofan aerodyne.mica
25、lly equivalent single-flap control surfacehaving a deflection equal to the deflection of the controlstick. The stick hinge-moment coefficient based on air- Jfoil chord is then .(2)It can bb ehown that the rate of change of stick.hinge-moment coefficient with stick deflection is. .(3) !lhe values of
26、the hinge-moment terms dbech 1w:. 61 .“Chl58 dt5aand ch + ch88 ah of equation (3) can be.read directly1 2Z,Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-11.from the cves press.n-ted in fi6res 3 to 6, The rate “of.change of stick-+i.pge-moment coeff
27、icient with angle of .attack may be expressed as“ The par theeffects of control chord and mechanical advantage havebeen taken into account byequations (1) and (2). TableII indicates that, although the value of cH for aa0.50C plain flap can be reduced by using A 0.50c doubleflap, the rearward flap of
28、 the combination was too smallto give an appreciable reduction in c=%” Because/ (.)has been reduced without a comparable reductionC%a 58in()c% therefore, no extrapolation of the curvesto highe.c lift is justified without increasing the slopeof the Vho-!.ecuTve In accordance wth the consequent in-cre
29、ase mechenicaj. advantage of the control surface overthe cotol stick. Conversely, if these curves are short-ened by decreasing 81tiaxt and hence cmaxt a corre-sponding decrease in the slope of eachcurve can be. .realized.The data shown in figure-8 indicate that, for positiyedeflections at attitudes
30、which are critical for rudder .(ao = 0 a?d 80), the stickliinge moment of 0.50c flapis many times as great as that of a 0.20c double flan. Atattitudes that are critical for elevator .(ao = -.120),however, the stick hinge moments of the double-flaparrangements lie between those of the 0.50c and the 0
31、.30cplain flaps. It should _be-noted that small hinge momentsare obtained from the 0.30c and the 0.50c flaps a-t U. = -12only b,ecause of the large floating tendencies of these flaps;whereas the 0.20c double flaps do not float appreciably.At a. = 6, the floati.tigtendency of the large-chord singlefl
32、ap acts to increase the stick hinge moment. The stickhinge moments of the 0.50c, the 0.30c, and the 0.20c singleflaps increase suddenly when a preliminary air-flow separation apparently occurs at about tliemiddle of the de-flection range; whereas the cHe-curve for the double flapis nearly linear. At
33、 small deflections, the Q.20c doubleflap has about the same stick hinge moment as the 0.20csingle flap but, at large deflections, the stick hingemoment of the double flap is decidedly less. This fact istrue with either sealed or open gaps. With open gaps, thehinge-moment curves for the double flap a
34、re nearly coinci-dent regardless of the relative rate of deflection of thetwo flaps d6a,/d81. lfith sealed gaps, the double flapProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-f14tended to give less stick hinge moment when the rearwardflap moved fast
35、er than the forward one. Table II indicatesthat, when d81/d8 was adjusted to give the same cfor each arrangement, however, the stick-moment parameterswere about the same.Although the stick hinge moments of the 0.20c doubleplain flap are much smaller than those of the 0.50c and0.30c plain flaps, they
36、 are not small enough for use asrudders or elevators on large high-speed airplanes. Thedouble flap is, however, well. adapted for use with theoverhang (inset hinge) or the internal type of aerodynamicbalance. It is believed that tests of such arrangementsare warranted on the basis of the promising r
37、esults ob-tained from the present investigation. A small-chordbalanced double flap of large lift effectiveness shouldmake a desirable aileron because the aileron span may bedecreased in proportion to the iucreased lift effective-ness and there%y may permit the use of large-span high-lift devices on
38、the v?.ng.,DragThe drag of each single- and double-flap arrangement:tested has been plotted for unstalled angles of attack infigures 3 to 6. A cross plot of drag data at an aagle ofattack of 0 is presented in figure 9 for tarious single-and double-flap arrangements. Unfortunately, no profile-drag da
39、ta for-a 0.50c flap were available for comparison.Figure 9 shows that, with sealed gap and at small liftcoefficients (c : “; . :-, .,” . .,. . .- ,. .-,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-“J6-4-0-/z-/6woreFig. .3d3.- Coriz%wed- ,.,-, ;-
40、- -, . . .:. . ,., ,. ., ,., .j. . . . . .,., ,.-., -,. -. .:, ,., : ., . ., :, , . . ., ., ,. ” ,. ,. ,., , :-, “ . . . - . . . . . . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IMCA Fig. 3e716”f120-? 04.%5 -8- .,.,._ . ?. .-, , .:. , . . . . .
41、 . .,. -. ”. . ., . , ,; ,. . . . . . . . ,=Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.0fNACA.080. G(e) Concluded. d, .20?. Rgure 3.-Cont%wed,- -. - _ . . . ., .- .,.:,.-. . , , . . . . . . . . ., .-. - -+. . . . . ,. . . . .-, -.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
