REG NACA-TR-610-1937 Tests of related forward-camber airfoils in the variable-density wind tunnel.pdf

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1、_: “-_ _ “ll_“ .:_ _-_NATIONAL ADVISO Y- -MITT EFOR AERDN UTILSREPORT No. 610INOF RELATED FOR_ARD-CAMBER AIRFOILSTHE VARIABLE-DES;SITY WIND TUNNELBy EASTMAN N, JACOBS, ROBERT M. PINKERTON ln A R : NEREPRINT OF REPORT No. G10. ORIGINALLY PUBLISHED NOVEMBE_l=- i!- = ml -_ iJ ,i _ ! i= i=- ! i- :-=- L-

2、 i i _1939 = , _i: llNATIONAL TECHNICALINFORMATION SERVICE :_U.S. DEPARTMENTOFCOMMERCESPRINGFIELD,VA. Z216! _ :_-;-_._JlProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-!?_ S,_ Area, of wingb Spanc Chordb_A Aspect ratio, _ _, Angle _f_ stabilizer sett

3、ing (relative_to thrust.:- -:-._ -“1line.)_“-:- - - - ._O Resultant moment_q -Resultant ang_ar velocityVI 7-.- -_ . -R Reynolds number, p where Sis alinear dimen- :Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-N 0 T I C ETHIS DOCUMENT HAS BEEN REPR

4、ODUCED FROMTHE BEST COPY FURNISHED US BY THE SPONSOR-ING AGENCY. ALTHOUGH IT IS RECOGNIZEDTHAT CERTAIN PORTIONS ARE ILLEGIBLE, ITMA K-ASIS BEING RELEASED IN THE INTEREST OFING AVAILABLE AS MUCH INFORMATIONPOSSIBLE.:TProvided by IHSNot for ResaleNo reproduction or networking permitted without license

5、 from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-REPORT No. 610TESTS OF RELATED FORWARD-CAMBER AIRFOILSIN THE VARIABLE.DENSITY WIND TUNNELBy EASTMAN N. JACOBS, ROBERT M. PINKERTON.and HARRY GREENBERGLangley Memorial Aeronautical Laborato

6、ryREPRINT OF REPORT No. 610, OB!GiNALLY PUBLISHED NOVEMBER 1937i-br 7Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSHEADQUARTERS. NAVY BUILDING, WASHINGTON. D. C.LABORATORIES. LANGLEY FIELD. VA.Created by a

7、ct of Congress approved March 3, 1915, for the supervision and direction of th$ scientific study of the problems offlight (U. S. Code, Title 50, Sec. 15i). Its membership was increased to 15 by act approved March 2, 1929. The members areappointed by the President, and serve as such without compensat

8、ion.JOSEPH S. AMES, Ph. D., Chairman,Baltimore, Md.VNNEVAR BUSH, Sc. Dr, Vice Chairman,Washington, D. C.CHARLES G. ABBOT, Sc. D.,Secretary, Smithsonian Institution.HEsav H. AR_:OLD, Major General, United States Army,Chief of Air Corps, War Department.GEoaas H. B_ErT, Brigadier Genera, United States

9、Army,Chief Matdriel Division, Air Corps, Wright Field, Dayton,Ohio.Lr._._ J. Bazacs, Ph.D.,Director, National Bureau of Standards.CLINTON M. HESTER, A. B., LL. B.,Administrator, Civil Aeronautics Authority,ROBERT H. HINCKLEY, A. B.,Chairman, CivilAeronautics Authority.JEROME C. HUNSAKER, SC. D.,Camb

10、ridge, Mass.SYnNEY M. KRAUS, Captain, United States Navy,Bureau of Aeronautics, Navy Department.CHARLES A. LINEnERGH, LL.D.,New York City.FRANCIS W. REICHELDERFER, A, B.,Chief, Upited States Weather Bureau.JOHN H. TOWERS, Rear Admiral, United States Navy,Chief, Bureau of Aeronautics, Navy Department

11、.EDWARD WARNER, SC. D.,Greenwich, Conn.ORVILLE WRIGHT, Se. V.,Dayton, Ohio.GEORGE W. LEWIS, Director of Aeronautical ResearchJoan F. VIcIoRY, SecretaryHENRY J. E. REID, Engineer-_n-Charge, Langley Memorial Aeronautical Laboratory, Langley Field, Va.JOHN J. lEE, Technical Assistant in Europe, Paris,

12、FrancsTECHNICAL COMMITTEESAERODYNAMICS AIRCRAFT STRUCTURESPOWER PLANTS FOR AIRCRAIrr AIRCRAFT ACCIDENTSAIRCRAFT MATERIALS INVENTIONS AND DESIGNSCoordination of Research Needs of Military and Civil AviationPreparalion of Research ProgramsAllocation of ProblemsPrevention of DuplicationConsideration of

13、 InventionsLANGLEY MEMORIAL AERONAUTICAL LABORATORYLANGLEY FIELD. VA.Unified conduct, for all agencies, of scientific research on thefundamental problems of flight.OFFICE OF AERONAUTICAL INTELLIGENCEWASHINGTON. D. CoCollection, classification, compilation, and dissemination ofscientific and technica

14、l information on aeronautics.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-REPORT No. 610TESTS OF RELATED FORWARD-CAMBER AIRFOILS IN THE VARIABLE-DENSITYWIND TUNNELBy EASTMAN N. JACOBS,ROBERT M. PINKEBTON, and HARRY GBEENBEaCSUMMARYA recent investi

15、gation of numerous related airfoilsindicated that positions of camber forward of the usuallocation resulted in an increase of the maximum llft. Asan extension of this investigation, a series of forward-camber airfoils has been developed, the members of whichshow airfoil characteristics superior to t

16、hose of the airfoilspredously investigated.The primary object of the report is to present fullycorrected results for airfoils in th_ useful range o.f shapes.With the data thus made available, an airplane designermay intelligently choose the best possible airfoil-sectlonshape for a given application

17、and may predict to a reason-able degree the aerodynamic characteristics to be expectedin flight from the section shape chosen.For airfoils of moderate thickness, the optimum camberposition was Jound to correspond to that of the N. A. C. A.23012 section. A discussion is included concerning thechoice

18、of the best thickness and camber for full-scaleapplications depending on specific design conditions.Data to assist in the choice of the optimum section for adesign using split flaps were obtained by testing some ofthe better sections with trailing-edge split flaps.INTRODUCTIONThe well-known airfoil-

19、section investigations in theN. A. C. A. variable-density wind tunnel have beendirected toward studies of the effects of variations ofairfoil-section shape. Such studies are intended todetermine the range within which the best possiblesection shapes for any given application will generallybe found.

20、With the data thus made available, anairplane designer may intelligently choose ttle bestpossible airfoil-section shape for a given applicationand may predict to a reasonable degree the aerodynamiccharacteristics to be expected in flight from the sectionshape chosen.The first investigation of this s

21、eries (reference 1)gave comparable data from the standard large Rey-holds Number tests in the variable-density tunnel,which were considered as representative within theflight range, for related airfoils covering section-shapevariations in the neighborhood of commonly usedairfoils. A subsequent inves

22、tigation (references 2 and3), covered by this report, deals with airfoil sectionsdiffering from those commonly used in that the camberoccurs farther forward, i. e., nearer the leading edge.The desirability of this shape characteristic was indi-cated by the first investigation.After the mean-line sha

23、pe designated 230 had beenfound to be near the optimum (reference 2), an airfoilhaving the N. A. C. A. 23012 section was tested in theN. A. C. A. full-scale tunnel to verify the superiorityof its characteristics over those of commonly used air-foils (reference 4). This and other tests (references 5a

24、nd 6) in the full-scale tunnel also provided valuabledata on which to base an interpretation of the variable-density-tunnel data as applied to flight. In addition,a selected group of the related airfoils has been testedover a wide rahge of values of the Reynolds Number.The results of this investigat

25、ior. (reference 6) providedthe information needed to apply the standard variable-density-tunnel airfoil data to flight at any particularvalue of the flight Reynolds Number.Aside from the presentation of the important sectioncharacteristics fully corrected for application to flightat the standard val

26、ue of the Reynolds Number(effective Reynolds Number approximately 8,000,000)for all the forward-camber series of airfoils tested, oneobject of the present report is to consider possible ira.provements of the N. A. C. A. 23012 section. Thispossibility was investigated by an analysis of testresults fo

27、r a number of airfoils, the shape of whichvaried systematically from the N. A. C. A. 23012.Finally, several airfoils within the most useful range ofshapes were investigated to provide data for the various airfoils that may be chosen as most efficient in par-ticular applications.lC_fProvided by IHSNo

28、t for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 REPORT NO. 610-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSThe airfoils developed in the variable-density-tunnelinvestigations have been designated by numbers bayingfour or more digits. As explained in reference l, ttl

29、emaximum ordinate of the mean line is called the“camber“ trod the position of tile maximum ordinateis Called the “position of th_ camber.“ The airfoilsreported in reference l were design.ated by a numberhaving four digits. The first digit indicated the camberin percent of chord; the second, the shap

30、e of the meanline as indicated by the position of the camber intentl_s of the chord from the leading edge; and the lasttwo, the maximum thickness in percent of tile chord.The extension of the investigation to the forward-camber airfoils presented herein (including the airfoilsin references 2 and 3)

31、necessitated an extension of thedesignation numbers to cover the new mean-lineshapes. As before, the first digit indicates the relativemagnitude of the camber; but the second has been re-placed by a pair of digits, which together indicate themean-line shape for which position of camber is one ofthe

32、parameters; and the last two, as before, indicatethe thickness of the airfoil section. The camber, themean-line shape designation, the corresponding valuesof camber, and the position of camber for these forward-camlet airfoils are given in the following table.“. Mean-line shape designation: (second

33、and third digits)Camberdos!g- “, Position of caznbe, (Actual camber in percent ofchord)3 _ _ 2.3 2.8 a.| 4 I 3.1l 3.71 4.21-The table thus indicates, for example, that the N. A.C. A. 230 - - airfoil has the camber 1.8 percent of the_hord at 0.15c behind the leading edge.The airfoils designated by bo

34、th the four and thefive digit numbers have only one form of thicknessvariation. Changes in the form of the thickness va-riation made by altering the leading-edge radius and the= position of maximu/il thickness (see reference 7) havebeen designated by appending two additional digits: separated by a d

35、ash from the basic airfoil designation.The first of these two digits indicates the relative magni-tude of the leading-edge radius and the second indicatesthe position of the max-imum thickness in tenths ofthe chord from the leading edge. The significance ofthe leading-edge radius designation is give

36、n below:0 designates sharp leading edge.3 designates one-fourth normal leading-edgeradius.6 designates normal leading-edge radius.9 designates three or more times normal leading-edge radius.The complete system of airfoil designation is illus-trated by the following examples: The N. A. C. A. 2212(ref

37、erence 1) has a camber of 2 percent of the chordat 0.2 of the chord from the leading edge and a thicknessof 12 percent of tile chord. The N. A. C. A. 0012(reference 1) is a symmetrical airfoil having a thicknessof 12 percent of the chord. The N. A. C. A. 24012(reference 2) has a camber of approximat

38、ely 2 percentof the chord (actually 2.1 of the chord, see table I)at 0,2 of tile cord from the leading edge and a thicknes_of 12 percent of the chord. It will be noted that theN. A. C. A. 2212 and the N. A. C. A. 24012 have prac-tically the same camber, camber position, and thickness;however, the sh

39、apes of the mean-camber lines, desig-nated by the digit 2 _n one case and 40 in the other, areentirely different. Finally the N. A. C. A. 0012-64is a symmetrical airfoil having a normal leading-edgeradius and the maximum thickness at 0.4 of the chordfrom the leading edge. The N. A. C. A. 24012-33 ha

40、sthe same mean line and thickness as the N. A. C. A.24012 but has a leading-edge radius one-fourth thenormal and the maximum thickness at 0.3 of the chordfrom the leading edge.The scope of the present investigation is best indi-cated by figure 1, which gives the profiles of the air-foils tested. Of

41、the airfoils of 12 percent thicknessthere are included a group of increasing camber: 00,230, 330, 430, and 630; a group of varyirig camber posi-tion: 210, 220, 230, 240, and 250; and some variationsof camber position for airfoils more highly camberedthan the 230 series. From the results of these tes

42、ts,the camber position corresponding to the series 230,430, and 630 appeared to be best, so that in most casesvariations of section thickness are included only forthese mean-line shapes and for the symmetrical airfoils.Some variations of thickness distribution are included,and also some of the more

43、interesting airfoils with ahlgh-llft device colasisting of a 20-percent-chord full-span split flap.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TESTS OF REI,ATED FORWARD-CAMBER-AIRFOILS IN THE VARIABLE-DENSITY WIND TUNNEL 3_. _ _ _ -0006 =33006000

44、9“001200150016002121012220128301224012Z501223009 _ 43009=_3012 430 22305 4301523010_302143018430213201233012340120012-630012-6442012: 43012_ 4401_23012-3423012-64430 2-A0018 - _-_*_3009 63009 _jT_OFloOgl l.-kirfoil proflle_.630096301263015630188302_0216302164021Provided by IHSNot for ResaleNo reprod

45、uction or networking permitted without license from IHS-,-,-_L. :i_=_-_, :i_REPORT NO. 610-NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSDESCRIPTION OF AIRFOILSThe thickness variations of the airfoils are given inreferences 1 and 7. The cambered airfoils have meanlines of the form given in reference 2.

46、 Profiles of allthe airfoils presented herein are shown in figure 1.The models are of 5-inch chord and 30-inch span, ofrectangular plan form, and are constructed of duraluminas explained in reference 8.APPARATUS AND METHODThe variable-density wind tunnel, in which the testswere made, is described in

47、 reference 8: Routine meas-urements of the lift, drag, and pitching moment weremade at an effective Reynolds Number of approxi-5ta t./p_ Lvo oZ_ 095 -_2Z.5 1.31 . L V5.0 /.78 :_7.5 2.10 , uI0 _ 34 -2, 4I_ _R7 2. 73.oo v40 2.90 : -2. _95O Z.65 2 560 2.28 .,2. 870 1.83 ./. L_80 1.3/ .I. t90 .72 . . ,_

48、L 95 .40 - . 00 I00 (06) -.d _)I00 0 0,. TTg-_-2:.o%_-and to the “blocking effect“ of the model in the tunnel.These errors have since been investigated (see theappendix of reference 6) and have been eliminated bycorrecting the manometer settings used in fixing thetunnel air speed. Other errors mentioned in reference1 have been somewhat reduced.RESULTSThe data are presented (figs. 2 to 51) in a mannerthat is a slight modification of the standard graphicform used in previous reports. The left-hand portionof the plot presents the test data in the usual stan