NASA NACA-WR-L-301-1941 Wind-tunnel investigation of control-surface characteristics III - a small aerodynamic balance of various nose shapes used with a 30-percent-chord flap on a.pdf

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1、t.a(b:!J.i-1,1,)ff/,.I,-.IL-IiARR Au-, . -Y .-. ,. .- -., .- , .-,. -_ _- _, :, . . . . . . .-. : ;.,.:. .-, . . .L“ ,- ,. ,.,. . . . . . -, . . ,.-. “., ,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3 1176013649943. .WIND-TUNNEL INVESTIGATION OE

2、 COIITROL-SURFACE CWWCTERISTICS111 - A SWILL AERODYNAMIC BALANCE OF VARIOUS NOSE SHAPESUSED WITH A 30-PERCENT-CHORD FLAP ON AM NACA 0009 AIRFOILBy Milton B. Ames, Jr.SUMWRYTests have been made in the NACA 4-,by 6-foot verticalwind tunnel of an NACA 0009 airfoil with a 30-percent-chordflap having a s

3、mall amount of aerodynamic balance.- In theinvestigation the effect of balance nose shape and gap atthe nose of the flap has been determined. A few tests weremade to determine the effectiveness of a tab on the bal-anced surface. The complete section aerodpamic character-istics of some of the arrange

4、m.snts tested are given. Apartial analysis of the data has been made, and the results arediscussed.The results indicate that, in general, the lift effec-tiveness of the flap was unaffected by the addition of asmall ount of aerodynamic overhang, and the balance ef-fectiveness of the flap was increase

5、d. The blunt-noseshape gave the greatest reduction in flap section hinge-moment. coefficient for moderate flap deflections, but forflap deflections greater than 200 the medium flap nose wasthe most effective in this respect. The presence of a gapat the flap nose reduced the lift effectiveness and th

6、ebalance effectiveness of the flap for all of the test con-ditions except when the angle of attack and the flap de-flection mere botb positive. The effects caused by thepresence of a gap increased as the taper of the flap noseshape increased. The characteristics of the tab were gen-erally unaffected

7、 by,aerodynamic overhang and flap noseshape. The minimum profile-drag coefficient of the air-foil with the flap having the most tapered nose shape wasabout 15 percent greater than for the airfoil with theblunt nose flap.Provided by IHSNot for ResaleNo reproduction or networking permitted without lic

8、ense from IHS-,-,-.2 .lNTRODUOTIONThe recent increases in speed and size of airplaneshave produced control forces of such magnitude that ithas becone increasingly important to reduce hinge momentson the controls and thus to reduce the forces on the con-trol stick. In an effort to obtain a satisfacto

9、ry solu-tion of the problem, the NACA has instituted an extensiveinvestigation to determine the aerodynamic characteristicsof control surfaces and to present adequate data for con-trol-surface design. -Because a conventional control sur-face is merely a flap on an airfoil, these tvo terms areused sy

10、nonymously. As a part of this investigation, someof the effects of flap nose shape and gap on a typicalhorizontal tail of finite span were determined in the “full-scale tunnel and are reported in reference 1. .The more basic part of”the investigation is, howeverbeing made in.a tvo-dimensional flow.

11、The first part ofthe two-dimensional flow investigation was the determina-tion of the section characteristics for airfoil-flap com-binations using plain flaps with sealed gaps at the flapnose. Flaps of various sizes from O to 100 percent ofthe airfoil chord were tested. (See references 2, 3, and4.)

12、The data presented in references 2, 3, and 4 haveeen analyzed and parameters for determining the charac-teristics of a thin symmetrical airfoil with a plain flapof any chord and with the gap at the flap nose sealed aregiven in reference 5. The results of force tests of aplain flap with various gaps

13、at the flap nose are presented ,in reference 6.The present report gives the results of tests of an . Iairfoil having a 30-percent-chord flap with a 20-percent-flap-chord overhang and a 20-percent-flap chord tab. Thetests were made to determine the effect of various flapnose shapes and several sizes

14、of gap at the flap nose onthe aerodynamic characteristics of the airfoil-flap-tabcombination. In order that the data might be made imme-diately available, only a very limited analysis of the ,.results has beeh made. .- -v-. ,.-.,.:-. =. .$ .- , .%;-.;,- -r,:-.-.,.; .:/.;,.,.“.: . . . “-. . . . .-4-

15、,., , ,. .- . +. : ,“ ., :Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3APPARaTUS MD MODELThe tests were made in the NACA 4- by 6-foot verticald wind tunnel (reference 7) , modified as described in ref-0y erence 2 for force tests of a model in a t

16、wo-dimensional1=1 flow. A three-component balance system has been installedin the tunnel. On this balance the aerodynamic forces oflift and drag and the pitching moments are measured inde-pendently and simultaneously. ghe hinge moments of theflap and the tab are measured with special torque-rod bal-

17、ances built into the model.The 2-foot-chord by 4-foot-span model was the samemodel used for the investigation in reference 6, but withmodifications so that tests could be made with a smalloverhanging balance on the flap. (See fig. 13) The modelwas made of laminated mahogany to the NACA 0009 profile,

18、the stations and ordinates of which are given in table I.The flap chord, measured from the flap-hinge axis to the.airfoil trailing edge, is 30 percent of the airfoil chord.The overhanging balance ahead of the flap-hinge axis is20 percent of the flap chord. The flap nose shape andthe gap between the

19、flap nose and the airfoil were variedby detachable flap nose blocks and airfoil tail blocksahead of the flap nose. The nose shapes tested are shownin figure 1 and were developed to give a systematic variat-ion of flap nose shape profile. The stations and ordi-nates for the various flap nose shapes a

20、re given in table11. The nose shapes are identified by numbers O, 8, 20,28, 28A, and 31 to indicate the approximate degrees theflap may be deflected before the 0.20cf overhanging flapnose protrudes beyond the contour of the airfoil profile:Nose shapes 8, 20, 28, and 31 are modified conic sections.No

21、se 28A is an application of a nose profile used in thetests of reference 1. The blunt nose, nose shape O, wasobtained, by making the leading-edge radius approximatelyone-half the airfoil section thickness at the radius cen-ter. The tab was made of brass,. and the nose radius isapproximately one-half

22、 the airfoil thickness at the tab-hinge axis. The gap between the tab and the flap wasfixed at 0.1 of 1 percent of the airfoil chord.The model, when mounted in the tunnel, completelyspanned the test section. With this type of installation,two-dimensional flow is approximated and the section char-act

23、eristics of the airfoil, flap, apd tab can be deter-mined. The model was attached to the balance frame byProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 .torque tubes, which extended through the sides of the tun-nel. (S6.8 refer8hce 2.) The angle o

24、f attack was set from.outside the tunnel by rotating the torque tubes with anelectric drive. Flap and tab deflections were set insidethe tunnel and -were held by ”frictiori clamps onthe torquerods whichwere used ii measuring the hinge moments. “., TESTS.The tests were made at a dynamic pressure .of

25、15 poundsper square foot which corresponds to an air velocity ofabout 76miles per hcr at standard sea-levl conditions.The effective Reynolcls number of te testswas “approxi-mately. 2,.760,000. (Effective Reynolds nlunber“= testReynolds number X turbulence” factor. The tur%ulence fac-tor. 9f the + by

26、 6-foot vertical tunel is 1.93.). . . .The six-flap no%e shapes. were tested “first with,the ,tab neutral anti the”gaat the. flap nose 0.5 of l.percentof the airfoil chord.: The preliminary results indicatedthat a satisfactry .investigat ion of flap nose shape char-acteristics could be Rade by testi

27、ng ocly the blunt-noseshape, O, the tiediua-nose shape, 20, and the sharp-noseShape, 31, arid these nose shapes will hereafter Veref,erredto as blunt ,.mediun; and sharp. . Accordingly, the tebtswere continued with the Q.005c gap and the three flap noseshapes previously mentioned to .det”erminqthe e

28、ffects offlap nose shape variation on the characteristics of a“O.ZOcf ta%. The t“edtsof the blunt-i medium-, and sharp-nose sha-pes.were”finally ,ext.ended to determine the effectsof gap sizes “atthe “flap”nose of 0.00Ic, “O.O1OC, and withthe gap sealed. Lift, hence the values presented are consider

29、ed to be conserva-tive. The increments of drag coefficients should be reansonably independent of”tunnel effect, although the abso-lute values of drag coefficient are subject to an undeter-mined correction. Inaccuracies in the airfoil and flapsection data presented are thought to be negligible rela-

30、,tive to the inaccuracies that will be incurred in the ap-plication of the data to finite airfoils. .Summary of Test Results In order that the results for the tests of the vari- .ous model configurations may be more easily found, a table has been prepared giving the-model arrangements tested andthe

31、figure numbers for the plots of the corresponding data.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Flapnose shape(Medium),(sharp),BluntMediumsharpBluntMediumShRrpGap size“o.005CsealedO.oolc0.005CO.olocsealedO.oolc0.005CO.olocsealedO.oolco.005C0.O

32、locFlap deflection(deg)0,5,10,15,20,25,30,45 0,10,25O,5,1O,15,2O,25,3OO,5,1O,15,2O,25,3O0,5,10,15,20,25,30l!abdeflection(deg)o,+10#15#20#30,-10,-15,-20,-30:esultsfig.)2a,h10,13all,12,13b3a3b3C3d4a4114C4d5a5b5C5dProvided by IHSNot for ResaleNo reproduction or networking permitted without license from

33、 IHS-,-,-.,DISCUSS IOI1.*!Che airfoil section lift coefficients and the flapsection hinge-mom”ent coefficients of the NAIXi 0009 airfoilwith a 0.30c flap having an aerodynamic overhang of 0.20cfand a gap of 0.005c at the flap nose are plotted againstangle of attack for the flap neutral in figure 2(a

34、), andagainst flap deflections for several angles of attack infigure 2(b), to show the effect of six variations of flapnose shape. The data in figures 2(a) and (b) indicatethat the effect of flap nose shape could be determinedsatisfactorily by considering only the O or blunt-, 20 ormedium-, and 31 o

35、r sharp-flap nose shapes. For this rea-son only the points for the blunt-”, medium-, and sharp-.flap nose shapes have been faired. The results of thetests to determine the section characteristics of the air-foil and blunt nose flap haviag the gap at the flap nosesealed are given in figure 3(a), with

36、 a gap of 0.00Ic in .figure 3(b), with a gap of 0.005c in figure 3(c), and witha gap of O.O1OC in figure 3(d). In figures 4(a), (b), . (c), and (d) and figures 5(a), (b) , (c) , and (d) the re-sults of tests for the various gap conditions for the flapwith medium- and sharp-flap nose shapes, respecti

37、vely arepresented. . .Lift -J act()The slope of the airfoil section lift “curve, ,00in agreement ith the results in reference 1, was only fslightly affected by variations of flap nose shape. (Seefi, 2(a).) The value of (ac )=Z was about 0.010 (fig. Z(a)which is in agreement with the value obtained i

38、n reference6. The most noticeable effect of the gap on cm was thereduction in (Cm)(5, the sealed-gapcoudition at ao= 0 proved to he the best arrangementfor all values of 6%greater than 20 with the mediumnose flap, where wit the O.O1OC gap the values of ACLwere the highest. Yor the high-positive angl

39、e-of-attackcondition the sealed gap vas best for the sharp nose flapat all flap deflections, while the medium nose flap at .values of 8f greater than 15 gave higher values of Aciwith the O.OIOc gap than with the gap sealed. The bestresults for the high angle-of-attack condition and theblunt nose fla

40、p were obtained with the 0.005c gap.Effect of flap nose shape.- As a result of the fore-going analysis, the flaps witn the blunt-, medium-, andsharp-nose shayes with gaps sealed were compared to givean indication of the effect of nose shape on the balanceeffectiveness. This comparison is shown in fi

41、gure 9.For angles of attack of -8 and 0 and at all positiveflap deflections up to about 20, the blunt-nose shapegave the least increment in flap hinge-moment coefficientfor a given lift coefficient iacrement. At no= 80 theblunt nose flap with a sealed gap was onl slightly %etterthan the other shapes

42、 for flap deflections up to 10, fromwhich point it became the poorest shape. If the gap at the nose of the blunt flap was 0.005c, however, this flapshape would be superior to the otheriflap shapes forvalues of .:“., ;“1:,.-: . . ., -,. : ,. -., . . . .-: ,.-, . . - . . . . ,- .,. ”.-,.Provided by IH

43、SNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-13.-l0q-ld.-nose shape and sealed-gap condition as a basis, the incre-ments of profile-drag coefficient with the medium-flapnose shape and sealed gap was about 0.0008, while with thesharp-nose shape and sealed gap th

44、e increment in profile-drag coefficient was 0.0015. Because of a relativelylarge unhewn tunnel correction, the drag coefficientscannot be considered as ai.)solute; however, the relativevalues should be independent of tunnel effects. .ParametersThe use of aerodynamic parameters (reference 5) is adire

45、ct means by which the characteristics of the differentflap nose shapes and the various amounts of aerodynamic%alance may be compared. while it is not within the scopeof this paper to make a complete analysis by this method,it is important that, in general, the effects of flapaerodynamic overhang, no

46、se shape, and gap on the parame-ters be treated.In agreement with the resizlts of reference 6, thevalue of ()%ao . : . “ , ; $+,. . . . . . . . . . . . . -,.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. . - - “,17. .TABLE 1.- 0RDIAT3SStations and

47、 ordinatesri Stationso1.252.5%5101523253040506073809095100100FOR NACA 0009 AIRFOILin percent of wing chord. IUpperI Lowerufae“+surfaceo1.42a962.6?3.153.614.014*3Q4.464.504.353.973.422.751.971.C9.60(.10)o0-1.42-1.96-2.67-3.15.-3.51-4.01-4.30-4.46-4.50-4.35-3.97-3.42-2.75-1.97-1.09,-(:;)0L. 3. radius:

48、 0.89Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.!2AELE II.- I?LAP NOSE SEAJ?E.Stations and ordinates for 0.30c flap with0.20cf overhang on NACA 0009 airfoilRose sapeStations(percent c)o.25,501.!)02.092.743.004.005.006.006.757.007.738.006.509.009.5010.2510.QNose rad0j8”120j2828A31Ordinzites .(percent c)o-1.161.582.10-2.402.582.702.71-2.“682.+*$:*Q+g%!.zJ2.411.45.0.55.791.131.59-1.932.182.412.52-2.