1、REPORT No. 677WIND-TUNNEL INVESTIGATION OF AN N. A. C. A 23021 AIRFOIL WITH VARIOUSARRANGEMENTS OF SLOTTED FLAPSBy CARLJ. W small change in pitchingmoment with flap deflection; 10IVforces required tooperate the flap; and freedom from possible hazard dueto icing.A very promising arrangement of a simp
2、le slotted flapdeveloped for the N. A. C. A. 23012 airfoil is reportedin reference 1. Further improvement, from a consider-ation of high lift coef6cients and low drag at Mgh andintermediate lift coefficients, was obtained by the addi-tion of an audiary slotted flap to the main fltip (ref-erence 2).
3、Another type of slotted flap, nerodynami-eaIly superior but structudy more complicated, is the-renet,ian-blindflap reported in referencc 3. Al theseflap arrangements were tested on the N. A. C. A. 23012airfoil.In the present report, the results are given of thetests of a relatively thick airfctiljth
4、e N. A. C. A. 23021,with several arrangements of 25.66-percent-chordsIottecl flaps. This investigation included two flapshapes, each of which was tested ttithseeralslot shupes.MODELSPLAIN tiEFOILThe bmic wing, or the plain airfoiI, used in thesetests was built to the N. A. C. A. 23021 proe nnd hm ac
5、hord of 3 feet and a spzmof 7 feet; the ordinates for thesection are given in table I. The model was built withsolid laminated mahogany nose and traibg-edgepieces and solid mahogany ribs. The portion betweenthe nose and the trailing edge n-ascovered with temperedwdboard. The trailing-edge section of
6、 this model waseasily removable so that the model could be quicldyaltered for k.sts of different flap arrangements.SLOTTEDFLAPSThe slotted flaps and the slot shapes were built ofsolid laminated mahogany. The slot shapes were bohedto the main airfoil in place of the solid trailing edge.The flaps were
7、 mounted on speoial hinges that permittedconsiderable hititude in the location of the flaps withrespect to the main ffirfoil.Flaps.-Two flap shapes were tested. Flap 1 (fig. 1and table I), corresponding to flap 1 of reference 1, hasrt smaU nose radius and was designed to give only asmall break in th
8、e airfoil lower surface when unreflected.It also lends itself ta use with a door to seal the break inthe lower surface of the airfoil with the flap unreflected.Flap 2 corresponds to flap 2 of reference 1, whichgave the lowest drag at high and intermediate lift co-efficients on the hT.A. C. A. 23012
9、airfoil. This flap isshown in figure 2 and its ordinates are given in table I-Thie flap shape was obtained by combining the nose of665Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-666 REPORT hO. 677NATIONAL ADVISORY COMMITTEE FOR AERONAUTICSan N. A
10、. C. A. 6330 airfoil with the trailing-edge portionof the main wing. It was designed h give low drag atintermediate and high lift coefficients.Slot shapes,-slot shape a, which was used in com-bination with both flaps, is shown in figures 1 (a) and2 (a). This slot shape was designed to give a m.humbr
11、eak in the lower surface -of the wing and, conse-quently, to have the smallest effect on the drag with theflap neutral. Slot shape b is similar to slot shape h ofreference 1, which gave the lowest drag at intermediate(a)%k“.oo ; .Olcu J.02CW(c)(a) FIw l-a (b) FlaP l-b. (r!) FlaP l-e.Fmwml.-awt.lone
12、of N. L O. A. 29021alrfot$with am.ngemente of slottd Sap 1.and high lift coefliciente for take-oil. This slot shapewas also used in combination with both flaps and isahown in figures 1 (b) and 2 (b). Slot shape c was espe-cially dqmd sc that a door could be used h close thebreak in the lower surface
13、 of the wing with the flapneutraL This slot shape was used only in combinationwith flap 1 and was similar to shape b except for theentry radius. Slot shape COhas a sharp entry, andshapes c1 and b have entry radii 1 and 2 percent of thewing chord, respectively. All the slots were designedto be sealed
14、 by the eIot lip at the etit on the upper sur-face of the wing with the flaps neutral.The modeIs were made to a tolerance of 5=0,015 inch.TESTSThe models were mounted in the closed teat sectionof the N. A. C. A. 7- by 10-foot wind tunnel so tlmt theycompletely apa.nnedthe jet except for smaII cleara
15、ncesat each end. (We references 1 and 4.) The main airfoilwas rigidly attached to the ba.hmce frame by torquetubes, which extended through the upper and the lowerboundaries of the tunnel. The ange of attack of themodel was set from outside the tunnel by rotating thetorque tubes with a calibrated dri
16、ve. Approxhntitelytwo-dimensional flow is obtained with this type of in-stallation and the section characteristics of the modelunder test can be determined.A dynamic pressure of 16.37 pounds per square footwas maintained for most of the tests, corresponding to svelocity of 80 miles per hour under st
17、andard atmospheric 56,2*I03 -(a) FIaPZ-a (b) FISP 2-b.FIGURE-!2-SeatIoneof N. A. C. A. Z1021akfoIl with armngwments of slotted flnp%conditions and to an average test ReynoMs Number ofabout 2,190,000. Because of the turbulence in the windtunnel, the effective Reynolds Number R, (reference 6)was appro
18、ximately 3,500,000. For all tests, R, is basedon the chord of the airfoil with the flap retracted and ona turhdence factor of 1.6 for the tunnel.Plain ahfoiL-Test.s were ft made of tho plainairfo over the complete angle-cf-attrtck range from6 to the stall. In addition to this test, scab-effecttests
19、were made of maximum lift coefficient over therange avai.Iablein the 7- by 10-foot wind tunnel.Slotted flaps.-With each slotted-flap arrangement,tests were made to determine the effect on minimumdrag of the breaks in the wing lower surface at the slotentrance with the flap retracted. Twts wero also
20、madeto determine the effect of the flap hinges with the flapsin their retracted positions. The tests of slotted flapsI-a, l-b, 2+, and 2b consisted in surveys of flapProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-AN N.A. C. A. 23021 M133OIL WITH SLO
21、TTED 3zAE3 667Position and deflection to determine the optimum pathof the flap from a consideration of low drag throughoutthe complete lift range and of the highest maximum liftfor each flap ddlection. TEsts were made of slottedflaps l-cO, l-cl, and 1-G along the optimum path asdetermined for slotte
22、d flap l-b. Data were obtainedfor alI tests throughout the angle-of-attack range from6 to the stall at 10 increnmuts of flap deflectionfrom 0 to 60. No data were obtained above the stallbecause of the unsteady conditions of, the model.Lift, drag, and pit-ub$1.*e0LQa* 16$- +31$am?$ .s k n P 4 .6 .8 L
23、os- iect?.mIif# coefficient qFIQUEE4-Eflect ofdot opentngs In lower eurfeea of drfoll on prodfedmg CoefEcfent.8f,(r.for all lift coefficients from zero lift to a lift coeilicientof 1.0. Slotted flaps l-q and lcL gave approximatelyconstant increments of profile-drag ccdlicient of about0.0010 and 0.00
24、12, respectively, up to a ift coefficientof 0.6, beyond which the increments increased to 0.001Sand 0.0022 at a lift coefEcient of 1.0. Slotted flapsl-ca and 2b gae about the same increment of profile-drag coefficient, 0.0014 to 0.0015, for lift coefficientsless than 0.6, beyond which the increments
25、 increasedto 0.0022 and 0.0018, respectively, at a lift coefficientof 1.0. Slotted flap Ib was inferior to all otherarrangements, the increment of proflklrag coef6cientincreasing nearly linearly from 0.0026 at zero lift to0.0030 at a lift coefficient of 1.0,It is probable that a door could be fitted
26、 to any ofthe arrangements in such a manner as to seal thebreak in the airfofl lower surface without measurablyincreasing the profile-drag coefficient of the wing withthe flap neutral over that of the phin wing.SLOTTED-FLAP ARRANGEMENTDetermination of optimum arrangements for maxi-mum lift,The data
27、presented in this section am theresults of the masimundift investigation of the variousflap-and+Iot combinations in which tile flap, at a givendeflection, was located at points over a considcwddoarea with respect to the main airfoil Tho duta aropresented as contours of the position of tho nosopoint
28、of the flap for a given lift coefficient, The mmpoint of the flap is defined as the point of tmgcncyof a line drawn perpendicuhw to tho airfofl C11Ordand tangent to the leading-edge arc of the flup whenneutral, as shown in figures I and Z,The complete maximum-lift data for slotted Ilaps1-s, lb, 2n,
29、and Z-b deflected 10, 20, 30, 40,50, af=lo”.s=- q+-1. (c) 6 2Percenf wtng chord(c) Cl-z. 61-2.V.Section aerodynamic characteristics of selected op-timum arrangements.-The complete section aero-dynamic characteristics of selected optimum arrange-ments of slotted flaps la, lb, 2-s, and 2b are givenin
30、figures 13 to 16, respectively. The optimum arrange-ments were chosen from a consideration of low drag” -coefficients at the specified lift coefficients for flapdeflections from 10 to 30 and from a consideration ofmaximum lift coefficient alone for flap deflections from40 to 60. In addition to the o
31、ptimum mmmgeme.nte,N complete data for otherpositions of the various flaps at the several flap defleg-t.ionsare avaiIable upon request.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-674 REPORT NO. 677NATIONAL ADVISORY CO.MMltiE FOR AERONAUTICS L._ 8
32、f-10.642 /At-cent wing chord (d)(b) et-l G bruaty I?J,1939. “REFERENCESWenzingm, Carl J.,” and Harris, “Thomas” A.: Wind-TunnelInvestigation of an N. A. C. “A23012”Airfoil R?th .Vti.OMArrangements of Slotted Ffaps. T. R. No. 664, N. A. C. A.,1939.Wenzinger, CarI J., and Gauvain, Wflliam E.: WincI-Tu
33、nneIInvestigation of an K. A. C. A. 28012 Airfoil with a SlottedFlap and Three Types of Auxiliarv Ffam T. R. No. 679,N. A. C. A., 1939.3. VTenainger, WA J., and Harris, Thomas A.: PreliminaryWind-Tunnel Investigation of an N. A. C. A. 23012Airfoilwith Various Arrangements of Venetian-Mind I?lws. T.
34、R.(to be published), N. A. C. A., 1940.4. Harris, Thomas A.: The 7 by 10 Foot Wiud TUIHIC1 of theNational Advfsory Commitke for Aeronautics. T. R.NO. 412,N. A. C. A., 1931.6. Jaoobs, Eastman N., and Sherman, Albert: Airfoil ScctkrnCharacteristics ss Affected by. Variations of tha ReynoldsNumber. T.
35、R. No. SS6, N. A. C. A., 1040.TABLE IORDINATES FOR AIRFOIL AND FLAP SHAPES16WOIIS and ordinate-qh PercaotofwingchordlJpmwars-4.676.147.939.1310.wu 19IL S2W11.4910.40.s.m7.696.05z 76L 62.22i m-a 14-4626. 56-6.327. 61-3J -2.3617.99 -1. s6g$ L50 -1.36. 81tio6 :% , 22I ICenterofL. E.8roL. EJWua: 4#.6. 610P6of radlua through end of chord: 0.30SL. E. radiua: LOOkrltorCartet of L E. erac12.W -0.56L. E. mdhrs: 2.S9Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
