RESEARCH MEMORANDUM. NATIONAL.ADVISORY COMMITTEE FOR AERONAUTICS ". WASHINGTON May 23,1947 ASPECT RATIO 4 AND NACA AIRFOIL SECTIONS AT

Transcription

1 .. RESEARCH MEMORANDUM. AERODYNAMIC CHARACTERJSTICS OF A 42' SWEPT-RACK WING WITH ASPECT RATIO 4 AND NACA AIRFOIL SECTIONS AT REYNOLDS N"BZRS FROM 1,700,000 TO 9,500,000 BY Robert EL Neely and D. William Comer.. "_.. "- NATIONAL.ADVISORY COMMITTEE FOR AERONAUTICS ". WASHINGTON May 23,1947 -

2 I Winir--tuImel teets were made of a 42O ewept-back wfng to determine low-bfeed aerod.pmmic characteristics in pitch and in yaw at hi& Xeyr;olde cm?jem. The cbamcteriatica in pftca were obtained over a Reynolrie number range fron I,700,OoO to 9,!j00,000 and the. cheracteristics in yaw, fron 1,700,000 to 5,300,000. The wing hed an aspect ratio of 4, a taper.ratio of 0.625, and NACA 64,-.E sirfoil sections nom1 to the chord line'. The ning ch9,racteristica at high aqgles of attack 17em greatly influsnced. by Remolds IW;L~)GT in the reage from 1,700,000 to 5,300,000 but were ifttle affected in the mge from?,3oo,ooo to 9,50O,C30. The principal effect of icsreasing the vahe of Reynolds nupiber was to delay wing stalllng to higher angles of attack.' The r~~~hmrn lift coefficieets in the hfgher range of Reynolds number were a%out 1.1 wilthout f bpe and about 1.3 with halfxp.~~ split f'lepa deflected 60'. Abrupt tip stalling caused unstable chmges in the pitching maneni; at mxcinum lift. The effective dfhedral parasaeter C 2 varied 9 approxhmtely lhearly xith lift coeffioient at a Repolde nw&er of 5,300,000 e3a reached a maximan value near mxlmun lift of about 0.OOh without flap and with flaps. I At Reynolds numbers greater than 1,700,000 roughness in the fom of appllsd to the w-3.q~ leading edge had a large adverse effect on lift, drag, and pitching-moment characteristics. Roughness SUO reduoed the aragimum values of C2 *

3 2 Highly swept-lack wl?&38 are being emplayed as a means of Wnimieing 'conpreeeibility effect8 at high lsubkic a d eupereonic speeds. Large m0unes of Bweep have, however, presented problems in obtaining adsqmte nwrhum lift and aatisfactory stability md control character&stica at low speeb. LOW-scale keets (see, for emle, referensee 1 and 2) 3ive shown that unsatisfactory variatfons in the hw-s-peed aero-mic characteristics my be obtained, which remlt to a large exkent from the spanvlee flow of the air in the bomdary layer. Because of the dependence of bomdezy-layer bebvior on Reynolds number, the need for ae-c data at large valiies of ReyiloXs number is apprent. Accordingly, wfnd-tunnel teats hsve been made in the -gley 19-foot presours turnel, of &'particular awept-back wkqg to determine Its low-speed characterietics up to rea~lonably high valuee.of Reynolds number. The ens had a aveepback angxe of 42'; an aspect ratio of 4, and. NACA a1-112 airfofl sectidna normal to the chord line. A e r o m c characterlatic8 in pitch were determined over a Reynolds nmhr range Frcm l,r;loo,boo to 9,fiW,OOO and.aerodymmfc characterietim in yaw,. from 1,700,000 to 5.,300,000, Testa were made cf the pbfrz 'iring, *e wing ;with gartial-span split flaps, anii tine wing with a spoiler-type latefal-c'ontroldevl.ce for conditione of leading edge -0th apd leading edge rot@.. c.1;. lfft' coefficient (F) drag coefficient cy lateral-force coefficient

4 3 Lift = -z n x Y Z L M drag ( -X at zero yaw) Icngitu.llnal force lateral force vertical force rolling moment pitching moment

5 4 NACA RM No, LV14 IJ S yawing moment wing area b c C mean aerc-c chord ; meaaured parallel P a X Y parallel to plane of eymmetry local chord; measured parallel to plesle of iq mnetu longitudinal distrn-ce from leading edgi of root chord to quarter-chord Doint of each ssctlon; measured. perallel to plene of symetry epanwlse coordlnate t. P ct a. free-strem velocity maas density of air coefficient of viacoslty velocity of ~ound MODEL The plan fora of the wing Is shown in figure 2 The angle of sweep of the leading edge is 42 and the wing sectfone prpendfcular to the chord Une are WACA airfoil seatiom. The chord line of each vlng pmel le the quarter-chord line of a stxalght panel which has been rotated 40 about the quarter-chord

6 point of its root chorc. The airfoil section8 parallel to the plane of eynrmetry bate a mxinum thickilesa of. 9.6 percent chord located approximately 38 percent chord. Tae espect ratio i,a 4.01 and the b taper ratio Is 0, tize are raunced off beginning at 0.9'75g in botb p h form and. crose section. The wing ha~ 120 geometric dihedral or tvtst of the Wlft flape is 50 percent of the wing span. (See fig. 2,) The flap chora is 18.4 percent of the whg chord and the flap defiectian with remect to the hinge Une $8 &) meaeured between the wing lowar surface and the flap. The instalktion of the spoiler ia shorn in figwe 3. The height of the spoiler, 0,052 chord, 5s equal to the xlag thickness &t the chordwise station where fhe SpoileP is located.. The wing W&E conetmtcted of Wmted Itlahogany and the ffaps &x& the spoiler were of sheet mbl. The wing wa8 lacquered md sanded to obtain a -0th surface. A leadlng-edge roughne~.~ was obtained Pg amlicatim of No. 60 (0.OlL-inch mesh) carbomdwn grains to a thfn layer of skex4c over a eurface length of 8 percent chord measured from the leading edge on both upper and. lower eurfaces. The grabs covered 5 to 10 percent of the affected area. The tests were mule in the Langley l9-foot preseure tunnel.. The mount'%g of %he wing for the pitch teets is shown in figure 4 and for the yaw teets in figure 5. For the yaw teste the end. of the sapport strut wa8 shiexsd by 8 fdring formed by a pa& of a sphere to which was attache& ELP afterbody. The fairing F~GS 20 inches long, 14 inches wide, and e23ended 4 inches below the wing surface. The pitch characteristics of the smooth and rough wlnga with and wlthout eplif flaps were determiiled at zero yaw through an angle-of-attack range at the following Reynolde llumbera and Mach numbers :

7 a070,098.eo.134.i06, Six-componea% eats vere olhafned for ths wing with spciler at a RefioZa numker of 3,3OO,OOO. Stall characteristic8 Yere studied at 3ep-olbs n1mters of I, 700, wo 6, &c!,~x)o by meam cf tufts attached to the upper eurface of the wing bcgirxdng at 20 percent chord for the wlng mooth and 10 percent chord for the wing rough; however, only data at a Reynold8 nlmber of 6,800,000 are preeented herein. The aerodyna-aic charecteristice of the wtng with the leading edge both moth and. rough were obtahed thyou& an angle-of-yaw range of -10' to 25'. at eeveral angles of attack for a Reynolds nmber of 5,3OO,OOO. The lateral-stability parenetera of the smooth. wl&g with and wit.hout flap were detemined from teate mde through an 8sgle-of-attack range for yaw angles of k5o at several values of Reynolds number tetwesn 1,700,b00.&nd 5,3CO,OoO e Similar teat8 were &e with the leading edge rough at a Reydolds..number of 5,30C,OCK!. CORRECTIGES TO DATA The effect8 of the two-support system (ftg. 4) & Uft, drag, and pitching moment were detemnined by tare tet3te and the data at zero yaw have been corrected for thee0 effects. No tare teats were made to determine the effect8 of the Bin& eupzort (fig. -5), but approxlmte comctione to the lift, drag, and pitching moment In yaw have been applied.. The data have also been corrected for airetroam misalinement.

8 The Jet-bormhry corrections to the angle of attack end. drag coefficient, which were calculated'at zero yaw from reference 3, are as follows : The correction tunnel-induced The correction to the.mllinr;t-niament coefficient due to the spoiler. -. as detedned from reference-4, for an unswept wing,is.... to the pitching-moment coefficient due to the dietortion of the loading Is ACm = o.ook, Aca - -o.0lec2 All these corrections were added to the uncorrected data. No correctfon h ~ been s applied for wake blockage (reference 5). -la correcticn which 1s &ependent oa the proftls dmg ie neg.ugible for most of the data preeented. For condftions of leading edge rough or hading t&ge smoo+ih at the loweet Reynolds number, cor'recting for &e blockags would reluce the absolute ~alrres of the coefficients by approximtely 2 percent at high angles of attack. Aerodynamic Characteristics in Pitch b a The lift. chamcterietics and the rollfng-moment characteristics near maximum lift are presented in f lgure 6. At BOW of the Ugh Reynolds numbers no test data were obtained beyond the stall because

9 8 HACA RM No. L7D14 of exceaeive model' vibrat?rpn. The mm5mm.lift cwffjciente as a -functio~ of Reynolae number are plotted 3x1 figure 7.. Raar;lte of tuft eurveys at a Reynolds nlunber of 6,&3030(30 are given in figuros 8 md 9. The -p,itching-mmnt coefficients are' prceented in figure 10 aa a'fwc.t;im of lift coefficient and aha, at high angleis of attack, a8 a function of engle of attack. Drag coef - ficients are given in fig.:re 11 and ~ome informtion on the inf'luence of the drag'variations on gli3.e CbEl%CteYi8tiCEl is given in figme 12. The aercdymmic characterietics of the wing with erpoilar are ctho-m in figurers 13 to 15. Lift and stzlllx characteristics.- For the.smooth wlng, the lift-curss~peuks~lg. 'G smoth &d well rounded at the lowet Reynolds number (1,?6,0,GOO) but becoma sharyer as the Reynclds nmber fa increaeed, U2 to E? Reynolds mm'ber of 6,&?@,Cyx! the, value of C increased with increaeirg Reynolds nmber. (See Lneuc ' ' fig.''7.) The value af C decreased slightly with furthc?r J-hX increaue in Reynolds nmber. The maxilnum values of CL verb 1.12 at a' = 19' flaps on. ID9.X Kith flape off 41d 1.33 at u = 17O wlth ebtainad ' I -For the rough wing, the lift-curve peeks are wel rounded a d Reynolils number has llttlo effect on Uft. The maximum lift coefficients,of approximtely 0.98 w3.th fhpe off and 1.02 with fag5 dfl &ow' the l ~ effectfvenee~ w at C of the flap on the rough wing. L X At Re~nolds numbers greater than 4,350,000 'the ~i;mrm lift coefficieht of the rough, nfng wi.th f Upa,on mer even bwer than the maximum,lift coefficient of the smooth wing with f hp.8 off. The tuft surveys show that quite different stall p~~gressi0i'l8 were ob.tafned dependjng o n, the Reynolds number or eurface conditicrn of the wing leading edge. Stall ~tudies. for the' moth wing at R = 6,800,000 (fig. 8) ehw outflow along the rear part of the begimlng at modemte lift coefficierits. Beyond CL the wlna max stalls rather abnrptly over the onter half of the wfng. This type of stall may be dangerous. in lending.. Stalling WB.~ not alwaya symetrical, aa can be seen by the stall etudies.in figure 8 and the rolling-mament data in figure 6, The asymmetrical stall resulte from asyrmnetries in the wing and/or.tunnil air flow. The etal~.pro~eaeions for the mooth wing at the loweet Reynolde number (1,7OO,oQ.?) an8 the progreseion for the rough ving at m y Reynolde nunbere were very similar. Thle similarity is also

10 . t borne out by. tbe. force data For the rough wbg (fig. -9) and for the.mooth wlcg.at R = I, 700,OOo (data not presented) abpreciable outflow was first oktained mar the leadfag e.&e over the outer part 'of the wing. ha Che.ajngle of attack was increaaed the general dfrectlon of' the tufts on au parts of the wing moved in a clockwise dir9ctio.n on the left wing and comterclockwlse on the right wing. Any region where the direction of the tufts w a forward ~ of the perpendicnlar to the wing center line ms interpreted as E stalled.region. stalliq begas near the Leading e$& (0.10~ to 0.20~) from 50 to 75 percent of the semlspan. Stalling'progreassd gradualy resmard and famed out until, at maximum lift, only the center third of the wizg was uhstalled; No large change8 in roll- momeilt occurrsd fgr the rough wing., -.. On the basis of the tuft, surveys the 'stalling cheracteristics. of both the smooth and the rough wfngs are conaidered undesirable because.. of tip stallirrg. Pitchinq-moment chamcterist5cs.- At R = 1,700,000 and at.a moderate value of llyt coefficient, there is a declded increaee in stalility a8 determined from the krietion of pitching-moment coefficient with Uft coefficient (fig. IO}. men at angles of attack several degrees below tliat for mali~m llft umta3le changee -in pitcmng-moment coefffcient occury, w-hich result in a pitchingmonent cwe. of a decided reflexed shape * The wstable ve-riation of the pitching-moment coefficient Etpperently results from separation which occgrred premturew OIL the outer part; of the w'mg. When the Reynolds number is fncreeeed to 4;350,000 and to higher values, the pitching-mcment curves are more neariy''linear up to the l~laximum lift &nd,for these condftims, unstable changes in pitching moment resulting fron tip etauing occur after the mkfmun lift coefficient has been attained. For Reynolde numbers of 6,&O,0OO to 9,500,000, initisl test results for tke wing with no fhpe, although limited, indicate only s1~~3.l variations in pitching-moment coefficient at high anglee of att.ack; hence the king for these condltfms might be considered to have margfna1,stamlity. Check tests, in which the wing surface was observed to have deteriorated slrghtly, ahow that the wing is definitely unstable at.the stall. For desi@ coaaideratiom, ft i4 more practical to consid-er the results of the check teats a8 representative. The wing with leadfng-edge rou@;hnssa exhibits in general the same of pitching-n;oment chsmcteristics at all Reynold8 nuuibers a8 were obtained with the moth. wing at R = 1,700,000.

11 Spoiler "-.ICcharact'eristfce,- The spoi.ler,produced a mx:lmum value of Cz- of about nth flaps on at moderate anglee of attack. This value is considered Low: for. the smooth winge, ' (figs. 13 asld 14) indicate that the spoiler effectivexwe decreaaeo ae maximum lift is approache3 and that the loes In effectlvenese i~f szlrsller when tie 'flaps are on, Data for the rdugh wing wtth fhpe off (fig. 15) show that'the spoiler I,? ineffective at lift coefficients abqye'o.7. Data for the wlng with,flapa on (not preeented) show that tbe epbjler.is ineffective at lift Coefficients greater tha.il ' A e r o m c CharacterietAcs in. Yaw The htemlstabiiity parametera and Gq af the smooth wfng are plotted in figure 16 ae a function of the lift.coefficieat for eeveral valuee of' Reynolde number. Similar data,for the mugh wing are given in figure 17.for a Reynold8 &&sr of 5,3OO,OOO. The lateral-stability parameters were obtained from the teetrs msde at ' 0 and?jo yaw. Aerodylamfc characterletics throu& a range of' yaw aslgle at eeveml eklglea of attack are presented in figurea 18 and 39. c+

12 RoILltng-mmnt chamcterfat1cb;- The variation of the effective dihedral gara3neter C with lift coefficient m e greatly influenced 4 by Raynolda number, particularly when the Reynolds nuniber vas increased from 1,~0,000 to 3,OOO,OOO. (See figt 16.) When the Reynolds nmiber was incressed the linear part.of t.he curve of.. extended over a greater lift-coefficfet range and &e meximum values of G'$ were increased..for the ufng with f,laps on,>'he slope of ~ the cume of Cz 4f % wae increaeed. also. The large ecale effect shown may be cue to the parkfcular airfoil section aployed; hence, this result should not be coneidered applicable to all wtng6. At a Rep~olciis rimer of 1,720,000 and with fbp8 off (ffg. 16(a)), increased linearly wfth CL in the low lift-coefficient range CzJ, end reached a mxfmm mlue of at CL = 0.5 to 0.7. The value of (22 then decreased and finally reversed in'.sign; that i8, a.* negative. dihedml effect "8 obluafned. Wtth flaps 01 and at the increased with lift coeffi- same Remolds nrlniber (fig. -16(53:) cient to a maximum value of o.@034 at CL = 1.05 then decreased rapidly. For R = 5,360,000, %he cun%s w&re linear over most of the lift range and t h mkinum values of C obtained were -, 4 about at CI; = 0.9 with flaps off and. 0.OOw at CL = with flaps on. The change in (2% per unit chaoge in CL ia!* approximtely in the lfnear ranrge of the curves for all conditione except for the cond.ftlon of fhpe on and R = 1,720,000, for which the c-e is For this wing,the almost blunt wing tips ma;g caatrtbute 88 much as 15 percent to the value of ac, l&l. (See reference 7.f $ The variatfans of Cz with lift coefficient for the rough 4f wing at a Reynolds 'lltzm5er of.~,300;000(ffg. 17) are sinilar to those for the smooth wing st a Reynold8 number af I,720,OCO.!Phe mximim values far the rough wing are approximately 6C3.percent of those for the -0th wing at a. Reynolds. number of 5,30O,OOO The ma~cinum values were obtained near the lift coefficient at wzch '' shlling firet besn (fig. 9). Little scab effect on CZ is GZJr $

13 12 NAbA RM No. L7D14 expected for the rough condltion Rmsmch as there was.onb a -11 male effect on the aerodynamic charecterietice of the rough wing in pitch. As an aid in interpreting the 'kluge of Cz in terms of 9. effective dlhehl, it may be noted that a unft change in geometric dihedral angie on a hoo swept-betck wfng cawed a change in C Parging from at CZ, - % o.2 to O.OOOI~ at cj; = 1.0 (reference 8) The elope of the cme of rolling-moment coefficient against angle of yaw (f fg. 18) decreased at angles of ~aw a3ove 10 for the moth wizig at hi& angles of attack. For the rough wing, the curve of C2 for the fihp6-clf, high angls-of-attack condition (ffg. 19) ha6 a neetive ehpe (negative effective dihedral) atsm~zll englee of raw but has a large poaitive dope at angle8 of. xaw above loo. Yawing-xment che.mcteristics.- The values of C for the ".., nu, moth,wing at, the- higher Reynolds nwhrs increased neptively with lift coefficient,which fndicates increasing directional stabiiity, Maximm values of C were about -0.Om8 at CL = 1.0 wzth flaps % off. and -O,OOl3 at % = 1.25 with flaps on. For the kooth wfng at R = 1,720,000 anrl for.the rough wing &.k R = 5,3OO,OOO, irregular v-ariatione in C, are shown in ffgures 16 and 17 at 4f moderate to high lift coefficients. As shown fn figure 18 the yawing-moment mzrve~ of the moth wing at hfgh mg$e of attack ahow reversala at anglee of yaw above 10'and 15. An invsstigation was made of a 42O swept-back wlng of aspect ratio 4, taper ratio 0.625, and XACA'64.1-l.E airfoil ~sctlfone to determine its low-spe6d aerodynanic chamcterietics in pitch and in yaw at high Reynolds numbers. The following concltmluns were indicated:

14 hgler M3morLal Aeronautical Uboratoqy.. National Advisory Comittee ' for Aerolaautioe Langlq Field, Va..

15 14. WCA EM No.. L7D14.,... ". 6. Gustafrjon, I?.i., and O'Sullivan, Willfas; J., Jr.: The Effect of Wfng Loading on Landing Technique and Dietbxe, with Experimental Data for the B-26 Airplane MCA ARR No. L4K07, Shortal, Jomph A. : Effect of Tip Shape and Dihedral on Lateml-Stability Characterietics NACA Rep. No 548, Maggin, Bernard, and Shanke, Robert E. : The Effect of Geometric Dihedxal on the Asrodynasllc Chamcterietfcs of a 4.0'Swept- Back Wing of Aspect Ratio 3. maca TN No. 1169,

16 . NACA R,M No. L7D14 +X +Y' Fig. 1 t +z NATIONAL ADVISORY COMHlnEE FOR AERONAUTICS

17 Fib=? 2.- Plan form of ring. Aspect retio, 4.01; area, GJ+3 square Inches; mean ael-odynercic choni, Inches

18 - 34./3* 1 I c 7 Figure.3.- Spoiler Installation

19

20 ... Figure 4.- Wing mounted for pitch tests in the Langley 19-foot pressure tunnel.

21

22 ..... P z 0 Figure 5.- Wing mounted for yaw tests in the Langley 19-foot pressure tunnel...

23

24 I H.8 P 0...

25 , -.O 4.OP c, 0 :OP 1.4 f c; p R'I

26 .,.... Figure 7.- f? NATIONAL ADVISORY COMMITTEE Foll AEMNAUTKS Variation of maxim lift coefficlent with Reynolds number,

27 Fig. 8. NACA RM No. L7D14 (a) Flaps off. (b) Normal on. flaps split Figure 8.-Stalling characteristics of 42" swept-back wing with leading edge smooth. R= 6,800,000. AZZ-~ZEL

28 NACA R.M No. L7D14 Fig. 9 rn (a) Flaps off. {bl Flaps on. kum -r oo*mmm- Figure 9.- Stalling characieristics of 42' swept-back wing with leading edge roughness. R=6,800,000.

29 , PO CL.4.e?

30 ... I......

31 ... H I

32 ..,. 1.4 /. 2 ID B CL.6.4.P 0.

33 L4 20 / cl allding speed 0 Plapa off, 1ead:ng edge smooth E Plapa off, leading edge rough NATIONAL ADVISORY A Flaps on, leadine; edge amooth COnHlTTEE FOR AEROIILUTICS v Flaps on, leading edge rough 0 0.O4.08./2./ nigurs 12.- Gllde chafaoterlstics of Uo swept-back wing for wlng londlng of 40 pounds MI- squrra foot. FxwrlrnsntRl data for R = e,loo,ooo

34 NACA RM No. L7D14 Fig. 13 PigUra 13.- Aerodyhamlc char?tctsrlstlcs of Uo saspt-back winf wlth apoilar. amooth; R = 5,7oO,OW;?= Oo. LSPdlng adgs

35 Fig. 14 NACA RM No. L7D14 Flgure a.- Aarodynmlc aharactariatlcs of 42' swept-baok wing with spoller. Leading sdue smooth; flaps on; R = 5,300,000; Oo. NATIONAL ADVISORY COHHITTEE FOR AERONAUTICS.

36 NACA RM No. L7D14 Fig. 15..

37 Fig. 16a.02 0 NACA RM No. L7D C LO 1.2 c, NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS (a) Flaps off. Figure 16.- Lateral-stability parameters of smooth wing at several valces of Reymlds number. I

38 NACA RM No. L7D Fig. 16b L cyfl 0 -.oz DO COHWITTEE FOR AERONAUTICS LO CL. (b) Flaps on. Figure 16.- Concluded.

39 Fig. 17 NACA RM No. L7D14.om LO LZ CL NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS Flgure 17.- Lateral-stability parameters of wing wlth leadihg-edge roughness. R = 5,3OO,OOO,

40 NACA RM No. L7D14 Fig. 18a./ 0.U8 ti- -06

41 Fig. 18b /.2 NACA RM No. L7Dl.4. LO

42 NACA RM No. L7D14 Fig. 19a.08

43 Fig. 19b BTACA RM No. L7D14 / t

44 -." 4