1、(NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS.WARIWIElum)ll-ORIGINALLY ISSUEDQ 1942 asAdvance Restricted ReportVZNT)-TUNNEZINVESTIGA1ICINOF CONTROL-SURFACECHARACTERISTICS. VII - A MEDIUM AERODYNAkC BALANCE 03TWO NOSESHAPES USED WITH A 30-PT-CHORDFLAPQNANl?ACA0015AIRFOILBy Riohard 1. Sears,and H. Page
2、 Hoard, Jr.Lengley Memorial Aeronautical IaboratozyWASHINGTONNACA WARTIME REPORTSarereprintsofpapersorim issuedtaproviderapiddistributionofadvanceresearchresultstoanauthorizedgrouprequiringthemforthewarefEort.Iheywerepre-viouslyheldunderasecuritystatusbutarenowunclassified.Someofthesereportswerenott
3、ech-nicallyedited.Allhavebeenreproducedwithoutchangeinordertoexpeditegeneraldistribution.L- 44aProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-3 11760136553041 :.4.0NATIONAL ADVISORY 00MMITTEE FOR AERONAUTICSADVANCE RESTRICTED REPORTWIND-TUNNEL INVES
4、TIGATION 03CONTROL-SURFACEI CHARACTERISTICS2 VII - A MEDIUM AERODYNAMIC BALANCE 03TWO NOSEASHAPES USED WITH A 30-PERCZNT-CHORDFLAP ON AN NACA 0015 AIRFOILBy Richard I. Sears and H. Page Hoggard, Jr.SUMU.RYForce-test measurements in two-dimensional flow havebeen made in the NACA 4- by 6-foot vertical
5、 tunnel of,tkmcharacteristics of an NACA 0015 airfoil with a balanaed”flap having a chord 30 percent of the airfoil chord and aflap-nose overhang 35 percent of the flap chord. The ef-feot on the aerodynamic section characteristics of the .shape of the flap-nose overhang and the gap at the flapnose w
6、as investigated. A few tests were made to deter-mine the effectiveness of a 20-percent-flap-chord tab onthe balanced control surface.The test results, presented in the form of aerody- namic seotion coefficients, indicate that the lift effec-tiveness of the flap was praotioall.y identical with thatof
7、 a similar flap previously tested on the NAOA 0009 air-foil and with that of a plain, unbalanced flap of the samechord on either airfoil. The slope.of the curve of hinge-moment coefficient as a function of angle of attaok waspositive over a smal range of angles of attack when thegap at the flap nose
8、 was unsealed. With a blunt-noseflap the variation of flap hinge-moment coefficient withflap deflection was about one-third, and tvith a medium-nose flap, about one-half that of a plain unbalanced flapof the same ohord on the same airfoil. The flap-noseoverhang was more effeotive as a balancing devi
9、ce whenthe gap at the flap nose was unsealed than when it wassealed.,.,Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2IHTRODUC!I!ION.The l?ACA has.instituted an extensive two-dimensional-flow investigation of the aerodynamic section characteris-tic
10、s of control surfaces in an effort to provide experi-mental data for design purposes and to determine the typesof flap arrangement best suited. for use as a control sur-face. In the first phase of this investigation the pres-sure distribution of the NACA 0Q09 irfofl with many sizesof plain flap ad t
11、ab was experimentally determined. !lheresults of these tests have been summarized in eference1, which preonts par.meters fo? determining some of thecharacteristics of a thin symmetrical airfoil with a plainflap of any chord,The second phase of the two-dimensional-flol investi-gation consisted. of fo
12、rce-test meastirernents of the charac-teristics of an NACA 0009 airfoil with a 30-percent-air-foil-chord fap Laving various amounts of aerod.yni,c bal-ance, various flap-nose shapes, .atidvarious sizes of gapat the flap nose. The reeults”of these tests are reportedin references 2, 3, 4, and 5. The-e
13、ffects of various cir-cular, elliptical and beveled trailing edges on hg hingemoment of a flap of thickened profile on the NACA 0009airfoil were investigated and the results are-presentedin reference 6.A series of tests has been undertaken to providedata for the NACfi 0015 airfoil vitli flap arrange
14、mentssimilar to those al.retidytested on the NACA 0009 airfoil. “The aerodynamic section charatiteristics of an ITACA 0015airfoil with a.30-percent-airfoil-chord (0.30c) plain “flap with a 20-percent-flap-chord (0.20cf) tab are givenin reference 7. The present paper presents the aerody-namic section
15、 characteristics of an NACA 0015 airfoilhaving a 0,30c flap with s 0035cf aerodynamic balance ofblunt and medium nose shaRes and a 0.20cf plain tab.APPARATUS AND MODXL.,The tests were made in the NACA 4- by 6-foot verticaltunnel described in reference 8. The test section ofthis tunnel has been conve
16、rted from the original open,circular, 5-foot-diameter jet to a closed, rectangular,.“.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-:;. . . 3an aerodynamic helanoe that exzjcdel forward of ths flep-hinga a,xis36 percent of the fl:lJchord. !Z%is tal
17、.aaoehiii”:h% th!sqntieof th flap was 0.5 of 1 percent ofth,eair.foil.c,h,p.rdand for tke seale-ap tssts it wag “ftlle-d wi “lgk.“,.- - -.,-. - -.:,. .,. ,-.,.6chtaThe subscripts outside the parenthesis indicate thefactors held constant when measuring the parameter.PrecisionThe accuracy of the data
18、$,sindicated by the devia-tion from zero of lift and moment coefficients at zeroangle of attack. The maximum error in effective angle ofattack et zero lift appears to be a%out *0.2. Flap de- ,flections were set to within *0.2. Tunnel corrections,experimentally determined in the 4- by 6-foot vertical
19、tunnel , were applied only to lift. The hinge moments$therefore, are probably slightly higher than would he ob-tained in free air and, consea.uently, the values pre-sented are considered to be conservative. The increments -,of drag should he reasonably independent of tunnel effect,although the absol
20、ute value is subject to an unknown cor-rection. Inaccuracies in the seotion data presented arethought to be negligible relative to inaccuracies thatwill be incurred in the application of the data to finiteairfoils.Presentation of DataThe aerodyni,c gectjj.oncharacteristics of the NACA0015 airfoil wi
21、th a balanced flap of %lunt and mediumnose shapes are presented in figures 2 and 3 as funotionsof airfoil section lift coefficients. Figures 2(a) and3(a) present the characteristics with the gap at the flPnose sealed; figures 2(b) and 3(b) present the character-istics with the gap equal to 0.005c. I
22、ncrements of dragcoefficient caused by deflection of the flap are pre-sented as a function of flap deflection at various anglesof attack in figure 4 for the arrangements of flap tested.The characteristics of a 0.20cf tab on the balanced flap-.with both blunt and medium flap-nose shapes are presented
23、in figures 5 and 6. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-7,.DISCUSSION OF AERODYNNIIC SE.CTION CHARACT!XRISTICSLiftRigures 2 and 3 indicate that the lift curves of theITAC4.0015 airfoil for the various flap deflections are ofthe same gener
24、al shape as those for the NACA 0009 airfoil(reference 5)0 At aay given flap deflection, however,the angle of attack at which the airfoil stalls is about5 greeter for the thicker airfoil than for the thinnerairfoil and, consequently, the maximum lift coefficient0$ the thicker airfoil is greater by ab
25、out 0.4. This ef-fect may be attrilnzted to the greater nose radius on thethicker airfoil.The slope of the lift curve ca is listed in tableIII for each combinaton of flap-nose shape and gap. Thevalue of ct was practically independent of the flap-anose shapes tested and decreased appreciably when the
26、 gapat the flap nose was unsealed. This fact is in agreementwith the results for the NACA 0009 eirfoil (reference 5).3oth with the gap sealed and unsealed, however, the slopefor the thicker airfoil vas somewhat less than. that forthe thinner airfoil.The effectiveness of thg flap in producing lift1()
27、axo.cl is tabulated for small flap deflections in table111. A comparison with the data of reference 7 indicatesthat the sealed flap with a 0.35cf overhang gave the samelift effectiveness as the plain flap. This result is inagreement with previous teets of balanced flaps on theI?ACA 0009 airfoil (ref
28、erences 2, 3, 4, and 5). A com-parison of the gresent data with the data of these ref-erences indicates that the lift effectiveness of the flapon the thicker airfoil is practically identical with thatfor the same chord flap on the thinner airfoil the relatire values, however, should %e iadogendent o
29、ftunnel effect. The increments of drag coefficient weredetermined ?)y deducting the drag ccefficieat of the air-foil with flap -d ta3 neutral from the drag coefficientwith flap deflected, all other factors being constant. .Provided by IHSNot for ResaleNo reproduction or networking permitted without
30、license from IHS-,-,-., . .-11m.=i-=!-AThe minimum profile drag of the airfoil vith a blunt-nose balanced flap was the same as that for the airfoilwith a plain flap (reference 7). The ninimum profile drago: the airfoil was greater by 0.0011 with the madium-noseoverhag than with the blunt-nose overha
31、ng. Ri6mre 4 in-dicate that the increments of profile-drag coefficientcause? hy flap deflection were of nearly the same magni-tude for”both the blunt and the medium nose-flap shapes.ith the gap unsealed the inurements of drag were gener-ally greater than with the gap sealed.-. Ta% Characteristics -,
32、. ,The increents of lift and flap hinge-nomerit coeffi-cients caused hy tal d.efleation, presented in.figures 5 .and. 6, iere obtained,%y theincrements caused _bytah defledtionliave been shown %y.pr?vious tests referents ) to e nearly irid.apendent offlap deflection. COUCLtiSIONS . .“Ehe result% of
33、the ,tesrtgof the”NA(YA0015 ,ai.rfoilvith a hal”anced flap having a Uhord 30 percent of theairfoil chord and a flap-nose overhang 35 percent of theflaD chord indicate the following conclusions when com-“pard with the rssults of previous tests of a similar“flap on the NACA 0009 airfoil: . .1. The slo
34、pe of thelift curve for. the NACA 0015airfoil was found to be independent of the flap-nose -shapeb tested and decreased appreciably when the gap atthe flak nose was unsealed. With the gap both sealed“and unsealed the lift-curve slopes for the NACA 0015airfoil were somewhat less than those for the lT
35、ACA 0009airfoil.tProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. . . - = =.,., .“.”. . .,. .: .-.,. . .,-,., ,.122. The lift effectiveness of the flap with an over-hang having a chord 35 percent of the flap chord on theNAOA 0015 airfoil was practic
36、ally identical with that ofthe similar flap on the NACA 0009 airfoil and with thatof the plain flap on either airfoil.3, The lift effectiveness of the flap with a sealedgap was independent of the nose shapes tested. The re-duction in lift effectiveness when a gap was introducedwas greater with the m
37、edium nose shape than with the bluntnose shape.4. When deflected in conjunction with the angle- of .attack, the blunt-nose flap lost all lift effectivenesswhen deflected greater than 15, but the medium-nose flapwas somewhat effective to 25. When deflected in opposi-tion to the angle of attackl the f
38、lap with either noseshape was effective to 25.5. The rate of change of flap section hinge-momentcoefficient with angle of attack was much smaller for theflap having an overhang 35 percent of the flap chord onthe NACA 0015 airfoil than for the similar flap on theNACA 0009 airfoil. The curves for the
39、thicker airfoilwere not so nearly linear as those for the thinner air-foil. Because of this nonlinearity, these values applyfor only a small range of angles of attack.6. The rate of change of flap section hinge-momentcoefficient with flap deflection was practically the samefor the balanced flap on %
40、oth the IIACA 0009 and the NAOA0015 airfoils.7. Unsealing the gap at the nose of the flap in-creased the balance effectiveness for flaps with both the%lunt and the medium nose shapes, The rate of change offlap section hinge-moment coefficient with angle of attackbecame positive over a small range of
41、 angles of attack.8. The curves of pitching-moment coefficient indi-cate that the aerodynamic center of the airfoil was 10+cated at the 0.23-chord station for the gap-sealed con-dition and approximately at the 0.23-chord point with theunsealed gap.9, The minimum profile drag of the airfoil with ablu
42、nt-nose balanced flap as the se as that for theplain flap, but with the medium-nose balance the minimumprofile-drag coefficient was increased by 0.0011. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1310. The increments of flap hinge-monent coeffi
43、cientcaused by tab deflection on the balanced flap were slightlySm81.er at nest angles of attack than those caused by atal op the plai,n flap. ,Langley Menorial Aeronautical Laboratory,l;,tionalAdvisory Committee for Aeronautics,Langley .iel, ?a.,.,:. ,. .,.,. . . .,. .Provided by IHSNot for ResaleN
44、o reproduction or networking permitted without license from IHS-,-,-14REF13RENCES1.2.3.4.5.6.7.8.Ames , Milton 3., Jr., and Sears, Richard I.:Determination of Control-Surface Charactvistiosfrom NACA Plain-Flap and labData. Rep. . 721,3?ACA, 1941,Sears, Richard I.: Wind-!l%nnel Investigation ofOontro
45、l-Surface Characteristics. I - Effect ofGap On the Aerodynamic Characteristics of an NACA0009 Airfoil with a 30-Percent-Chord Plain Flap.NACA A.R.R., June 1941.Sears, Richard I., and Hoggard, H. page Jr. : Wind-Tunnel Investigation of Control-Surface Character-istics. II - A Large Aerodynamic Balanc
46、e of Varl-ous Nose Shapes with a 30-Percent-Chord Flap on anNACA 0009 Airfoil. NACA A.R.R., Aug. 1941.Ames, Milton B., Jr.: Wind-Tunnel Investigation ofControl-Surfaoe Characteristics. III - A SmallAerodynamic Balance of Various Nose Shapes Usedwith a 30-Percent-Chord Flap on an NACA 0009 Air-foil.
47、NACA A.811.O1$16)Lowersurfaceo-2.37 -S.27-4.44-5.25-5.85-6.68a717.17-7.43-7.50-7.25-6.62-5.70-4.58-3.28-1.81.-1.01(-.16.)oL. E. radius: 2.48Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-16TABLE II.- STATIONS AND ORDINATES0.35cf 0V3RHANGStati On(per
48、cent c)o.15a71 901.902.903.904.906.908.9010.9013.0014.67FOR MEDIUM-NOSEOrdinate(percent c)o.902.122.923.453.804.074.404504.454.274.06Fair to NACA 0015profile to trailing edgeNose radius = 1.75 percent c. .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.17.TABLE III.- PARAMIWER VALUES NOR 0.300 YLAPWITH 0.35cf OVERHANG ON NACA 0015 A.IRI?OIL.,.Parameters.-Blunt nose shapeGapsealed0,093-.58-.00190039.020-.160Gap0.00
