1、. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS TECHNICAL NOTE KO. 10tt.6 P3ELINXNARY WIND-TCNKEL INVESTIGATION AT LOW SPEED OF STABILITY AXD CONTROL CIiARACTER- ISTICS 3F SAEFT-BACK WIi!GS E3y Viillia? Letko and Alex Goodnan Langley Yemorial Aeronautical Laboratory Lsngley Field, Va. Washington April
2、 1946 t Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-. - A Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Tests vvere cDnducted on Entapere6 constant-span win;s of 3“, 30, kfj, and 60 sweepback. T
3、ke purp3se of these tests was to investigate t;?le effect Qf swee7bncX on stability and control characteristics. bllity at moderate lift coefficients for the !+5Q and 60 sweqt-back wings. TPie lateral stability, the slo2e of the lifb curve, and the effectiveness of the diler2n and the snlit flap at
4、srriall ansles 3i attack vdried nith an,-lc of stveepback about ti3 much ds liocld be exFected frm sinnle tkx.oret;chl consi2erutioi:s. hp3ilers :#ere much less effective tkan woL:lr; be Inchcate6. by simple the 7r-y. 11 tile snent .iin,s .iitli il*ns JieLbtrdl reachzd d m;ixf:nii,;, nlue of abauc L
5、e3 eff ctive rtik.sclral dt so:ie lift coeff icierit. IX-ooping tlie vrili; ti?s- clecreksee tlie slpe of rolling-m2nent Cilrve _jlotted ainst angle f yaw. Recaicsc the reducti9n increased vvi th increase in lift coefficient, drooving t:,e tip3 h:,pt.lred t:, be a prmislnz :!icans of re?ucinL the ii
6、nfaTJoraD1c ldteral sca- bili b-r chdrhcterlstics of :;in,-;s with large s;fee:7back. T%e 4hta showed. large changes in longitudinal stu- / The ailerons were capble of trimming oL;t t:ie rollfnt; moment caused by only snall ang1.cs a? sideslip :gr tne 1) hichl;. swe!it-bac!c wings, The small che in
7、itching, rnq ?elit caused by aileron .!eflect,ion mricated that ivving- tip elevators having swept-back hin,;a lines woLlc4 be relatively ineffective on nigkly swe;)t-bacli winSs. The maxirnu;,i lift .;itti f 18-13 neu trsl remained back. The incre:,c.nt of Provided by IHSNot for ResaleNo reproducti
8、on or networking permitted without license from IHS-,-,-.-_- maxlmljlfl llft caksed by the split-f lap deflection decreiised with anzle of sweepback to approximately 0 for the 603 swept-back wing. -_ TNTRODTJCTIOG :uch interlest has been sI;ova in the possibility of using vin,-s iiith large anounts
9、of swee?bzck for high- speed xissiles and aircr1 inost irLportant factor in deter- mining compressibility effects and Doints out that, froa cgnsideration of corcpressibility, tiie critical fli,;-ht Mach number of a swept-back fling should be hither than that of an unswept injing. Tn 3rder to minilii
10、ze the adverse effects of comnressibility at nigh Idackl nwbers, the angle of sweep sLrould be such thst the co,nnoiient of velocity normal to the leading ediTe ?Des not exceed thzt corresp3nding to the crltical Nach nunber 9f th6 airioil 3ections. Since very little ta are available on wings having
11、an(;Ies (Jf sweep greater than fu, tests of an exIiioratary nature were made of xings kaving m,;les c?! swcfr;:,jck of 00, 300, 1-50, and 63). These tci5t.s ;vel :nUini:L;s The effect 10: sweepback on the effectiveness of an aileron, a s;slit fla?, (ind a s?oiler nas Investisated for eacii s?J!eepba
12、ck an,;le tested. The effsct of a tested with zero sweepback. APPARATUS AND iil3DELS The present tests were c9ndL;cted in the 6- by 6-foot teqt section gf the Langley stability tunnel. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I i; For IXS of t
13、he tests the tii?s of the wings Vvere tigs of revolution, but drqoyed ti;s were hlso teste?, 3n tkie 1,3 swc.r,t-bacic , ing. of the -Jing to 5? inches. ?r(l ec 1;s increasee tlie suan (See fitas. 1 ai(? 2(a).) The mo6el ,vas xounted an the L;lree-strl?t support hn6 because the mele-of-atthclc skin2
14、 Lor ;n,les of sseepbdclr of 30, 1,5O, and 600 bas lon;, a cr3ss bar was required to furnish additional rigidity 52 t,he iiodel. fii;3. 2(a) and 2(b).) (See Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-7 All the tests idere rLn at CI dyi?,ic press
15、me ;I 59.7 pounes yer sLlu-re foot. rLl:is vlue correspsnls tJ a -1ach nunber 3f aboit 0.165. The Rcyn3lds nur,ber varie?, frail about 990,000 to about l,gEO,SOO because the cnord of the wing, measure? parallel to the axis Df s;.nt?letry, :VS a functign of sweep. ?or each of the sv;ept-back o!Jings,
16、 tests were inade to 26 sit Oo and f53 yam. For each 3f these 2rdW anjles the uncorrected angle of attack was varied frorn in 23 increrrlents. For each adle of sweepback, tests were also made at oo and 100 an2,le iif attack for varying The ailemn tests were rnade drith miles 3f 0“ and tl5O deflectio
17、n for each sweepback angle. The split flar, tested wcis sst at a deflectian of 69;“. In each cast: the angles of deflection were measured in a ulane perpeneicular to the leacling edge of the wing. Althoush the spoiler lieiInd tunnel size The f3110v/iAlg taLle d,.ivts 123 of the correction factors us
18、ed for each c)f the s4:ci-lt-back flings: 1Jo corrections were applied ts the hta to take into account the tunnel-wall effect r3n the :tiode1 at large yaw angles when the win$ tips were very close.to the tunnel Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
19、 IHS-,-,-9 r“ 1- Llie bhsic dhta obtaine:d frorfi thse tests are presented in figures. 3 to 35 and an index of these figures is given in tsble I S+me results are scmmrized and cmpqred with theoretical results ir; fipres 36 t3 I.?. A cor-:-. ,s.Jaris,ri ril“ the data of figures 3 to 35 incicaites T;
20、3iffermrcs b=etwsea the chayacterist; cs of a wins with no siiec?back and wings ;litii large mounts of sneepback. Tnese di.ff erences af attack. -. Plain wings.- ?he decrease in ?e slope of the lift curve with sweepback and aspect ratio is shown in figure 56 nith an estimated curve. ria133 was appro
21、ximately independent of tne ,anC;le of sweepback, but the ang,le 9: attack at :Iiaximum lift varied nehrly inversely as the cosine of the le of swee9back. The r,ia;timuq lift coefficient 3f the win,s uithout The sha;3e f the curves 01 lifr; ad pitching moment 9f the niL,nly swLpt-back wings as a fun
22、ction 3? mqle 3f attack aie decideZly nonliriear (figs. 3(a), lO(a), hnd l(a). The “JinU iiith GO3 s,ieepback ht about CL= 0.3 and the xing with k53 sweepback ht about CL = 0.75 sho an increase ih the slope of the lift curve .md a diving tehdeiicy, indicated by the sucleen chance in slope of the D i
23、t chin;. -K men t cur ve . 2.n PncreasB in load bt the ti?s, gossiblg acco:-irmnied by a re.-i:varcl shift of tke center of wessxe at each sectioii. Tuft observati2n at thls attitude inciicates the air flgw t2 oe rJu tendency f swe:Jt-back viinzs mas encguntered; thls tendency is indi- - cated by th
24、e rqunding of the lift curve, by the unstable slope of the ?itching-monent curve, and by large increases in drag;. The longitudinal-farce coefficient near Cj+= is at least 5 tinyes as great for tha idin; with sweep- back as fgr the unsxept $ding (fE.;s. S(b) and 27(b). Ti12 -The s 3 ckiaxib c t e r
25、i s t i c s i 11 c7 i cat e Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The adverse effects 3n 19ngtlLpee tip decreased. CI?;. in ;,roF?rti3n ti an inci*easa in CL. The si?e force and yawin?, *-ioments ck.,aii,e ranidly and irregularly when the w
26、in is yawed at lift coefficients greater than the critical vhliles -:;hen the diving mo:i!ent occurs. At small lift cQeffici,ents tine directiDnal-stu- bility Cn, is srLall but favorable; except for the 60 swept-back itring at negative Ci, tnii increases as sone wwer greater than the first ;soaer of
27、 the absolute - value of the lift coefficient; this increase indicates tk-at the *yairiing nment is caused mainly by the differences in drag of the t-uo sides of tne win2 uken yawed. The ?moped tins increased the directiondl stability of tlie win2 with 15“ sweepback at small lift coefficients but ha
28、c? no apnreciable effect at larde lift coefficients (fig. 12(c). Ailerons.- The effectiveness of a half-span 0.20 aileron on each of the various wings tested is inciicated in fiLwre 40 by the slopes measured botvYeen f-lro ailcr9n deflection for CL = 0.2. Similar variati(3ns can be expectec! lip to
29、a lift coefficient of 3.5. Tlie marked decrease in Zileron effcctiveness with svreepb;ck canbined Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-with the narlted increase in 27y+ indicates that irYith hiwnding to :iiitliwi CL with f laDs neutral (fi
30、g. 3c) a The ccrves of figures 5(c), l5(c) .el Lz tics of the 9swept-T)ack %wings fron -che measurAecJ cl;Lir,r LP:. 3 r,Ics of the unsweyit wing. These concents j:?volJc +Yc dssunption that changes in sweep- back ali,le, btuiried hy pivoting tl2e sen.ispm of a giv6n wing ahouG an axi-s in tlie plzi
31、ne of symmetry, affect 7;he loading over each seiiispan only insofar as sweep affects the coiponents 3f velocity noma1 to the leading edge and Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-the an;les of attack of these ve1oc;ty c9,r:ponents witkL r
32、esnect to the planes of the win,: sernis.sans. ;,hen the wink;s are swept back in the :Tarme? indicated (that is, the areas of the wing 3anels and tne s:Jan neasured parallol t? the leading edge are Kaintafned const,ant ) , the f ?ll,iint; cniractsristics ans of the previously discussec? conce?ts, B
33、etz (reference 1) derived an expression for the rolling-nornent coefficient caused by sideslip as affected by sweep. In Bet21 s analysis, hvrevei-, the type of swee? considered was one in which t;ie lcacling edge rif the swept wing bias maintained in 6 h.3rizont;al plwe regardless of the angle of at
34、tack of the wing. This type 0: sweep represents a condition in which the angle between the planes of the left and right senispan wings (iihe?ral angle) varies with angle of attkcx and does not a2plg theref9re to the conf igmations of the wings considered in the present investigation (that is, wings
35、swept in a mmner such that the angle betvicen the planes of the right an6 left semispan winss is rriaLntainecj at LGoO, 31: zer9 dihedral, regardless of the angle of attack). kn equation, based on the saxe simglified assumptEons ulade by Botz ,(reference l), has been derived -to apply to the nin.ss
36、(swept in the manner just discussec!) of the present investigatign. This equa- tion, which gi-ves values of Czo equal to one-half tbse obtained by netz, is as fo1lov:s: L tan A - CZQ - - - 57.3 4 The dashed curve of figure 39 was obttined by adding t? the value of ;IS aetermined bg the relationship
37、lust given, the expcrimental value of (dC ,/dc,)-. - The agreencnt between the experimental and estimated curves is tood biit :tig Le fQrtuitous beckuse of the assumqtions mbde in the derivation of the theo- retical relationship. COnTCLUSIdiVS Results of tests in the Langley stability tunnel of unta
38、pered constant-span xirigs hving ancles of sweepback Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IC xwcA TIT NO. 1046 e. Snqfler effectiveness in -7
39、roducing rolling moments decreasec? with sweepback n:uch faster than be3uld be indi- cated bv the zim3le theory. Tl,e 1t.rge cind fav2rable yawing moments prqducec! by ciie s-oiler in$icated tliat spoilers may be qf s3me use in directional control. Provided by IHSNot for ResaleNo reproduction or net
40、working permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fi gir e Angle of sweenback, A Iratlo (deg) i A 60 60 60
41、60 60 60 60 1; 5 k5 45 45 k5 15 15 15 I ;i: 30 .3 0 30 30 30 30 0 0 0 0 0 0 0 G 0 7.3 1 2.52 2.52 2.52 2.52 2.52 2.52 2.52 4.13 4.02 k.02 3.56 3.56 3.56 3.56 3 056 3.55 1;. .s 6 L, .gc L.34 4 36 4-46 4.36 5.05, 5-05 5 003 5 -03 5 -03 5 -03 4 *13 z:; _- 20 - ITqDEX OF FIGVRES lJoi?el configuration Pl
42、ain wing buing -f- ailemn vking + aileron hing + sgoiler Wing + snoiler Yiing + split flap ;iing + split flap Plain wing iiiing + (?rooned tips biing + drooped tips Plain wing Yiing + aileron Yiirig + aileron hins + spQiler hing + spoilel- hfng + split flag ,;ing + splii; flap Plain wing .w:ing + ai
43、leron :,ing + aileron iving + spoiler !i8jing + sljoiler i,ing + split flap Plain xing Yin6 + aileron ii.ng + afleron Wing + spoiler ;ding + spoiler Wing + split flap Wing + split flap ?lain wing P1ai.n wing .I 1,. . 1 -. . , L.1 .tin6 + slit flap .- , . . lata plotted aeains t NATIONAL ADVI SORY C
44、OME I TT EE F 0 R HER 0 KAlrT I C S Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN No. 1046 Fig. 1 L- .50 -A NATIONAL ADVISOPV COWWITTIE IOI Af
45、MUITKS Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN No. 1046 Fig. 2a Provided by IHSNot for ResaleNo reproduction or networking permitted wit
46、hout license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN No. 1046 Fig. 2b Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
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