1、-, .-,.:, j$k.:,.*: -fleeted 13.50 within the airfoil contour in order to pro-vide a Bmoother S1O% entry, and also completely removed.An angle-of-attaok range from 6 to the angle ofattaclc for maximum lift was covered in 2 Increment foreach test. No data were obtained for angles of attackabove the s
2、tall because of the unsteady confiltion of themodel= Lift , drag, and pitching moment were measured ateach angle of attack.RESULTS AND DISCUSSIONCoefficients and SymbolsAll the test results are given In standard eectionnondimenelonal coefficient form corrected for tunnewalleffect and turbulence as e
3、zplained in reference 1.section lift coefficient (I+JN)Od section profile-drag coefficient (do/qo)oCm(a. c.)o eection pitchinmoment coefficient aboutaerodynamic center of plain airfoil 1.(a, c.)o /qc?Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6
4、1%)0 -msection pltahiag-moment coefficientat maximum section lift coefficientclm8%Cdreinwheretdo%.c.)ocTPandReIt1maximum 8ection lift coefficientminimum section profile-drag coefficientsection liftsection profle dragsection pitahing moment about aerodynamiccenter of platn airfoildynamic pressure.( )
5、LpVazchord of basic airfoil with flap fully retractedvelocity, feet per eecondmas= density of aireffective Reynolds =Umberdistance from aerodynamic center of airfoilto center of pressure of tail, expressedin airfoil chordsangle of attack for infinite aepect ratiofore-flap deflection, measured betwee
6、nfore-flap chord and airfoil chordrearflap deflection, measured between rear-flap chord and airfoil chorddistance from airfoil upper-surface llp tofore-flap-nose point, measured parallelto alrfoll chord and posltlve when fore- .flap-nose point ie ahead of lipProvided by IHSNot for ResaleNo reproduct
7、ion or networking permitted without license from IHS-,-,-Y. . 7b. , “.YI -”“dttitbnce from airfoil uppem-surface llp tofore-flap-nose point, measured perpendi-cular to airfoil chord and positive whenfore-flap-nose point 5s below lip.aYadietance from fore-flap trailing edge torear-flap-nose point, me
8、asured parallelto alrfoll chord and positive when rear-flanose point is ahead of fore-flap 1.:-trailing edge ,.distance from fore-flap trailing edge torear-flap-nose point, measured perpendi-cular to airfoil chord and positive whenrear-flap nose Is below fore-flap trailingedgePrecisionThe accuracy o
9、f the various measurement is %ellevedto be within the following limlts:ao, degreee . , a71 . . , . . a71 . . . . . . . a71 . +OOl.-c +0. 03ma= ,m.9;* a71 . 9 a71 s a71 a71 a71 9 . . . a71 . . . a , . . .Cm(a. ca)o . . . . . . . . . . . . . . . . *0.003ad a71 . . . a71 . . a71 .“. . a71 . . . a71 a71
10、 , . . +o,of)o” “Cmin .+0. 0006“%(01= 1.) a71 .“ “ “ “ “ “ Q“ a71 . a71 .- .m. . 8 9 a71 a71Bfl and 8fa, degrees . . . . . . . . . . . . . +0.2,-Elapposition. . , . . . . . . ,-, . . . . . j,XOOOlc”Mo corrections were “determlnd (ar applieii) for the “effect of the airfoil or flap. fittings bocatits
11、eof thelarge number of tee%a required,. It.is. believkd that .their “.effect, howerer, 1semall and that the relative values ofthe resulte would not be appreciably affeoted.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Plain AirfoilThe complete aero
12、dynamic section characteristicsof the plain I?ACA 23012 airfoil (from reference 1) areprssented in figure 3. Inasmuch ae these data havepreviously been discussed (reference 1), no furthere+lap Ahead of lip-. -;Below lip “bposition (perc:;:r;rfoll (pere:r:rfoil Ctmax1 2 3 2=742 2 2I3.153 2 2 3.30In a
13、lmoet all caeee, the highest value of maximum seotionlift coefficient for the flap-deflection range investi-gated was obtained at afa = 60.Erom the contours of rear-flap-noOe position forClmaxt a designer should be able to determine the bestpath to be followed by the rear flap at all deflectionswith
14、in the range testOd, fro a consideration of Orilymaximum seotion lift coefficient. The range of flappoeitlon8 covered. tia believed sufficient to allow farany deviation or compromises from the Best llftn path.Complete aerodynamic section characteristics for theoptimum rear-flanose poslton for both l
15、ift and drag=t each foreflap deflection and position will oe pre-sented subsequently in this report.Minimum Srofile da.- Contours of rear-fle.p-nooeposition for values of minimum section profile-drag co-efficient at specific seotion lift coefficients and flap .deflections are presented In figures 7
16、to 9 for the three sfore-flap positions. A comparison of the contour of flure 7(a with the section profile-drag characteristicsof the plain airfoil (fig. 3) indicates that the plainairfoil gives the lower drag.at seotion lift c.oeffiaientsof 1,5 or iese.At position 1, the oontours of Cd are presente
17、donly for valuee of 8f of 10, 20, ad 30, since itIs believed that the lrger flap deflections at this po-sition would not he used because the co”rrespondlng cdo values are quite high. Inasmuch as all the contours ateaoh of the three fore-flap positions wsre not closedabout the Indioated optimum rear-
18、flanose positione, itie apparent that a sufficient range of rear-flap positionswas not covered and that the true optimum values may exietat some other positions. The contours also indicate thatProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10more th
19、an one region of relatively low drag exists forBeveral rearflap deflection. AB anticipated, the min-imum section profil-drag hoefficlent increased withdeflection of the rear flap at any given lift coeffL-clent. At the Oame lift coefficient and rear-flap deflection, values of profile-drag coefficient
20、 became lossas the fore flap waa extended; for example, at cl = 1G5,6f= = 300, an optimum value of cd. of 0s050 was ob-tained at position 2 as compared to a value of 0,063 atposition 1, and at cl = 2.5, 8fa = 50, fian optimumvalue of cd. of 0.103 was obtained at position 3 ascompared to a value of 0
21、.117 at position 2. The optimumrear-flanose position moved forward and up, closer tothe fore-flap lip ag the fore flap was extended and alaoas the rear flap was deflected.Mor all these contours (figs. 7 to 9), In each p-sitlon of the fore flap at hgh lift coefficients andflap deflections, a given mo
22、vement of the rear-flap+nosepoint caused a greater change in the value of cdoeInasmuch as the rear-flap-nose positions for maxi-mum lift and minimum drag generally do not coincide, acompromise is necessary; therefore complete aerodynamicsectiou aheracterletlcg are presented for both conditions.Pltch
23、in ou9n.- The contours of rear-flap-noseposition-for. valuefa of Cm(a,c. o) at specific flapdeflections and lift coefficients are presented in fig-ures 10 to 12 for each of the three fore-flap positions-Because the positive increment of lift usually obtainedwith increased flap deflection has: its ce
24、ntroid fartherto the rear than doee an equal lift Increment obtainedby increased angle of attack, an Increase in the negativepitching moment of the airfoil is anticipated when theflap is defectedm The contours for cm(a.c.)o tend,therefore, to close near the region of the rear-flanoseposition for max
25、imum lift, and the positions of the rear-flap nose for maximum lift and maximum pitching momentueually coincide.The negative section pitchinmoment coefficientsusually Increased with lift coefficient and flap deflec-tion and the change in Cm(a. c.)o for a given change inProvided by IHSNot for ResaleN
26、o reproduction or networking permitted without license from IHS-,-,-11w. rea-flap.+mee. p,ostlon .bec.a-melarger ae both thesevariablea “Inareaaede At a g%;m lift coefffclknt; -the -negat+e valueta of m(a.c.)m also Incrsased as thefore flap was extended and d;flected. It appears de-irable therefore
27、to use the minimum flap deflectlo”n orextension necemeary to obtain a given lift coeftlclentmWith” these comtours of rear-flap position for “Cma. a.)n available (figs. 10 to .12), a demigner candetermin or anticipate the seotlon pftching-moment C-efflciente to be encountered within the range of posl
28、tlons and deflections Invamtigated,Aerodynamic Section Characteristic of SelectedOptimum ConfiguratlonOThe complete aerodynamic eection characterietice ofthe airfoil with the optimum-lift and cptimum-drag p-sltions of the rear flap at each flap deflection and ateach of the three selected fore-flap p
29、ositions are prsented in figures 13 to 15. These figures indicate thatthe lift-curve slcpes decreased with increased flap de-flection. The angle of attack for a75aximum lift usuallydecreased with Increamed flap deflection at each poeition,but in some Instances remained practltially onnstaht, Itwill
30、be noted that the aerodynamic section characteristicsfor optimum lift for 8fa = 70 are preseuted only fcrposition 3 (fig, 15(a), Teet.s were made at 8fa = Glo”In both positicns 2 and 3, but Insufficient data wereobtained to present the characteristics for the optimumrear-flap position for poeitlon 2
31、 or the contours foreither fore flap poeition; however, at posltlon 3, fromdata gathered at 8f = 700 and other deflections, Itis believed that theaoptimum-llft position of the rearflap wae attained. The aerodynamic characteristics aretherefore given.Yhe section pitchinmoment coefficients in genaralI
32、ncreaeed negatively with the rear-flap deflection andae the fore flap was extended. The slopes of the sectionpltchln+moment curvee wero negative at low angles ofattack and low flap deflections and were usually positiveat high angles of attack and htgh flap deflections. At.Provided by IHSNot for Resa
33、leNo reproduction or networking permitted without license from IHS-,-,-12high section llft coefficients, lower negatie valuesof m(a, c,)o wereethkrefore sometimes obtained witha large flap deflection than with a small one. Tt willbe noted in figures 13 and 14 that at 6f= = 50 and 60,respectively, th
34、e position of the rear flip for maximumlift coinoidbs with that for minimum drag, indicatingthis position to be best from both considerations. Infigures 13(a) and 14(a), the irregularities in the curvesIndioate that changing flow conditions existed at 8f=60Increment of tiaxlmum Section Lift Coeffici
35、ent.- The -effeot of flap deflection on Act for each of themaxthree fore flap positions is indicated in figure 16.The increment of maximum section lift coefficient, basedon the maximum section lift coefficient of the plain air-foil, increased not only with rear-flap deflection butalso as the fore fl
36、ap was extendeil and deflected.The values of “lmax for the optimum-lift reaflap positions are higher than those for optimum dragexcept at position 1, 8f = 50,a and position 2,8f= = 60, where the two values coincide. The maximumincrement within the range investigated at each fore-flapposition occurre
37、d at Sf = oo, except for the optimdrag curve of position 1? The maximum Increment, whichwas obtained at position 3, was about 1.75, In position1 “lmax Increased only slightly for rear-flap deflec-tions above 30, and in position 3, the decrease inACImm wag fairly small between 8f = 60 and 70.athis di
38、fference Inad amounted to as much as Omb2 nt cl = 2-9, At sectionli!?t coofficiente le6s than 1-6 and higher than 3.1 thepolars for optimup lift and optimum drag, however, almostcoincide.A comparison of the seotlon pitchinmoment coeffi-cients at the maximum section lift coeffiolents for thevarlou6 f
39、lap arrangements preciously disouesed is givenin figure 19. The variation of 1m(ac cm) ith0 cImax01max appears to be dependent upon.flap arrangement-The arran ement reported herein gave higher” +alues of . Fm(a*QL than any of the slotted flaps but its .,maxvalues are approximately equal to those of
40、the”Fowlerarrangement- -.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-14The 10BS of airplane maximum section lift coeffcient in trmming the alrfoll se”otion pltohinmomentcoefficient is given by the expression1Cm(a.cm)o,=tLoss of Clmax =tail langth
41、r ItCurves of loss of Clmax for tall lengths It of 2, 30and 5 airfoil chord lengths are presented tn figure 19and can be used for determining the effective maximum “section ltft coefficient.Effect of Various Modifications onAerodynamic Section CharacterleticBEffect of moving the two flaps as a unit
42、- In fi -a71urea 20 and 21 are presented the aerodynamic section char-acteristics of the airfoil showing the effect of movingthe rear flap and fore flap A as a unit. Figure 20 indi-cates that a O.OIC dleplacement of the flaps upward pekpendicular to the airfoil chord had only a small advergeeffect;
43、however, a O.OIC movement of the flaps downwardwas quite critical because greatly decreased values ofc and Increased values of cd. were obtained.The effect of a forward movement of OOOIC of theflaps Is shown in figure 21; only a slight effect In theaerodynamic characteristics was obtained.Brom these
44、 dataz It is indicated that some positionsand deflections of the flaps are quite critical: that 1s,a movement of as little as O.OIC may appreciably alter thecharacteristics obtained.Effect of the airfoil lower lim.- The effect of de- .flector removing the lower llp of the airfoil fromits normal posi
45、tion is Indicated in figures 22 and 23for different flap configurations. It ie indicated infigures 22 and 23 that slightly more favorable sectioncharacteristics may be obtained by removing or deflootingthe lip. The profile drag appears to be slightly lesswith the lip off than with the lip deflected.
46、 Such aresult Indicates that a smoother slot entry ahead of theflaps mar be desirable. Although no data were obtainedat emall flap deflections, It is probable that the-. . ., -,.-,. ,Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1?.15smoother slot
47、entry would be even more favorable underDnuoh aonddti.ons. ,-. . - . .,., - -ff,- The effeot of for-flapBize on the” aerodypamio section oharaoteristlas Ie shownin figure 24. A oompartson of the section charaoterltics of the airfoil for one configuration with fore flapB and” two roughly comparable c
48、onfigurations with foreflap A Indioates that the size of the fore flap has n- “tlaeable but small effects. The characteristics forthe optimum position of fore flap B indicate values ogOa, dol and m(a.oj)o sltghtly greater than thoseof fore flap A at all angles of attaok. With fore flapB, a value of Clmax of 3.35 wag obtained, which 18only 0.05 greaten than the cmax obtained with foreflap A, The configuration with the smaller fore flapthat Is more.nearly geometrically similar to that of the larger fore flap (
