Document
ACR No. 3120 \, kJ
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
trl RTIMl RI Pi)RT
ORIGINALLY ISSUED September 1943 as Advance Confidential Report 3120 WIHD-_ INVESTIGATION OF A LOW--DRAG AIRFOIL SECTION WI_ A DO_BLE S_ FLAP By Seymour M. Bogdonoff L_ey Memorial Aeronautical Laboratory Langley Field, Va.
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NACA
WASHINGTON !_ACA WARTIME REPOI_TS are reprints of papers originally issued to provide rapid distribution of iw,i: ;_ r,_:_earchresults to an authorized group requiring them for the war effort, fhey were pre- • ,.i ;u:;iy :_eiUwnder a security status but are now unclassLfled. Scme of these reports were not tech- hi;ally _-c[ted. AlL have been reproduced without change in order to expedite general cistribution.
REPRODUCED BY NATIONAL TECHNICAL L- 697 INFORMATION SERVICE U.S. DEPARTMENT OFCOMMERCE SPRINGFIELD, VA. 22161 .
NATIONAl, ADVISORY COMMITTF.E FOR A_0NAUT!CS ADVA}TCE CO_TID21NT!AL R!t$O_T WII,)D-_7_.r£1, II,_.q_STIGATION O_ A LC_-D_A_ AIi_d_Ol!, ST;CTIO!_ !{l_ A DCUBIS _',LOTq_-T.'_ I,'L_2 Z,v Seym,]ur M. Bo_donoff S_RY TotS,': of a 0.309-c}:ord dou])le-slotted :['lap on an L_ACA 65_" o .j-]to, a = 1.O airfo:_l section h,_ve Leen _-,_de f.n the _,._,_.T,,_ t',.ro-dimensional low-turbulence tunnel and tLe N!\CA two- dimensional !ow-_urbulence pressure tunnel. The purpose of the inve_t:<y_abion was to deteriJdne t]'e ]ii%, _.ra,c, and pitching- mo',_.entcharacteristics fcr a ranF_,e of l']_t;) __' _"_" . u,_._,c,. _zonso The re_ults :'ndicate that the combination of a low-drag airfoil ana, a double-slotted f].c.p of which the %we p_ris moved _s s slnif41e unit ga,_e hizl:,er _aximum lift coefficients than have been obtained wi[h plain , split, or s].e±_ed flaps on lo_.- drag airfoils. The maximum lift coefficients were almost as high as those obtained on conventiorm], airfoils of about the same thickness with O.40..chord venetian-blind end double-slotted flaps. The pitehin_ moments were comparable to tI:'.ose obtained with other hi zh lift devices on conven+_iona], airfoils for similar lift coefficients.
IN_lqODUC TI ON The _,TACA has for some time been Inves%igatln 6 airfoils eguipped with Ligh lift devices for the p_rpose of improving the perfor;;mne clm,racteristics o:f those airfoils. The results of tosts of low--drag airfo:!_is equipped with plain, _plib, or slotted flaps have boon presented in reference i. The results .... _ o_ re:[trances _,> and 3 show that, on conventional air- foils, 11',ehighe,st lifts have been obiainod with large-chord venetian-blind and double-slotted flaps. The present inves- ti(;ation was made to determine the lift, drag, and pitching- moment characteristics of a low-drag airfoil with a dou_le- slotted flap at vcrious flap deflections. In addition, the optimtu_ position for maximum lift and the fl:_p path were to be found.
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I'relimlnaz_y tests were marie to detez::inc the be::t per<tilth of the fore fl,= r rel,.,_iee to _e reu, r flap c_: [,he b:_.s.t:.: c: ¢ m:zimum seCtiun lif6 coefficient C_mn.x cbtaine_: :,,t ,?: flap dofl¢c:.i<:n of' _5 ° m' • .n_s m?reey of fo_'e-f]a i _osition m,_n i:;::dl;ed i.o bhose _,?sit:to:is ,_5 which the fla-,) could 1"6 rehracte< without heovinz the f<>re ll:_,ppro t_.de boyonC ti.:e;,i:'i'uils:urfaco. The re:_r .?lap _zd fore :,.'l:_p wele then fixe.__ !.:_the Le_t ro].c:biv_ p,.:sibion _:¢ :.he proco.:]ure was repeated for the unit. 'i'he Yl%p pt_,fh was so chr,sen thutj at 45 ° dcfl_ction, the :flap "va:_ :!n a [;o,_it:i<.n at _:h:_ch both r_LuJts wei'e offuctive ,_nd_ al. 550 3eflection, t-.he['!np was in a r.osition at which mtuwim_m .!.if b war.: re:ached. One ]/ivot point we3 used fc::" fla_.t , e,]oct,on_ ......... :s.. to,. o-_' ," whcreu,_o ....:I:.,,:,,_o.L p:.vo ..no:Ln5 w_:', used fez' doflectic:n;_ from 45 to 65. (i:_e z:!g. 1,) Lift, drag, and pitchir_g moments were obtained for flap de_[f.ections r.q_=_ing from O° to 65 ° • Lift al.d dr;, G data were obtalnod at a }_eynold_ number of _;()00_00_I m:d p'.tchi:lg-mume_zb dat.-_, wore cbta?ned at a Rcync,.Id_ number <;f ';:500_000. Scale effect c,n ,ma::i_r,_ lift _.rasfo:u:d lot a range of i_c.y±m].ds _J_mber;_ f_,om II-,000_OC,O to 9_000_000.
PESIU, TS /_.:I: DISCUS,qIO_: The results oY the fl_p-position survey r,f r, he dou]_le-sl:/hted fl<p for _h_3 flap po_::t '[on that w.-,ulr_ g:_'..e m-0:<i:,_um ]ift ?re p:,e,_onte,:!
in fi,6_,:r_2. :Section lift, character'.stics for the. c<mbina, ti?_:_with the flap deflected throu£/_ a rag.Co of anglo_ frc_ 0 ° 1o 650 are presented in figure 3 for a Bejno!r]s num:bez- of appro__i_._'_te!2 6_000_000, The m-,zxi_emmsection lift ¢oefficiert obtr_im*e:_. _,ras3.40 at o, fl:_.p deflection of 65°_ ac which sa% :..... zemen,, in ma,_':imum],ift c< e:?ficien< of shout 1.79 w_s obtained. Comb7.el;e d._.,ta to,' only one double- slotted ±'lap a_e presertte:, but _::<?v!ous unpublished tests h,_ve shown th,_,,, a ,Jecre:_:-_o in ca.:rd o:d the fore flap gave a decre.._.so _n the m_x:irrmm litt obte, i:.,._fb!e. The so:,,]e euCi:ec:; on me_i:iw.m lifl. cr_effi- cient was fmnd to be negligible <,re.., the z':,nge el' P,eyn¢lds n:_r:fbers t,e_::,,_. The sr::_l! jogs .i.n the lift curves_ which s,pLear fc,r _,h.e 0 c and lo° f].eop dofloct-o::u_ ::<." not occur at dm higher dc, z'lecti<_,n::.
Sccti,3n _::j[; cha:,-_.cterist.cs for the comb:Jn'_ti')n f<,r flap deflecti,?ns i'rrm,..0(? to 35 ? :<r_ presel_t, ed ::,:_ fi£:_re 4. ff'he::,e he:_+,s were ?.%inat a _oynolds nursber of ap_rc.xim_uelj 6_000_000. For bhe flap retracted and dof:'lect_d 10°_ fairly l<,_.r r l:'a¢_ coefficicntv, are obtainable over a r,__:go o:I?],ift ;: officien!,::, f:'om about -0.2 :o O.S_ which it:eludes the normal hi_n-si,:,ced :_nd cr_:L _in:z-ff.icht con]J.tion_._.
The relabive!y low (!r_.g obt[d_ned i/or the 35 ° deflection is pr,:...b_$1g i Repr°duced fr°m @ best _vailable copy.
due to the establisi_ent of smot.th .lov. through the _nin slot At a flap deflection cf 3_ °, a section lif%-dr<g of ,-<_;pro>'i_,tely 170 ._y be ' _'*°" _ o, .... inec at a lift coefficient of a],'ou_ i.o.
For deflections above 35 ° no drag measurements were taken, but _-isual observa£ion of the wake-survey r_anometer ir-dica%ed that the dress were :_ot excessive• 'i_e Ligh lifts with com- paratively low d;cs_? ere ±he result -_" un_;ta!led f]o.vs over the flap, as was indmcated by t_ft surve_ which s_hc_,;ed no separ- ation of the flow eve-, _ the flap ur: to a L .... _,_s..... _i.n.... .
- _..... , ,-_ 65 ° Sect ion pi<: :.q_,in s-.rjomcnt charac;,-_ri! ,;_ t ; ,, s fk' t!_o airr'o i L.- flap combination for a].k fl_ap def'loctioi_s t;s_,:C ,_<.;b u;es_nt, ed in figure S. Although pitching.-.momer_t ,:o_ff:lci_?I:_-_ m.>_ mc, asurcd a£ a Reynolds nurJber oz 4;SOOjO00; little ci_o.n¢,,i> these char- acteristics is expected for el, her RoDi .[de rkt,zix,'_,.r:, b_;s[_rL,_e _'1 4- f previous bests of o._ot,.4_dflai.s on. low-.drag w,lnc_s _referor}.ce I) have shovm that, ior i :]_. t :: below maxT;'-m.m_ s<a]_ <. .,:c< o,_ pitching molsJnts is veal," small.
The _ouble .... ' d - -s_os_._ flap tested Sa_.e a llrt c¢,:fficient higher %han t_i_oe obtained on the _ , ..
±o_r-.:ra< ar_.ri c:.:,.l: -_ with _lain, split, or slotted f].aIs rq_'.oried in reference i. The 0.309- chord ' '" ' .........
(_ou_,le-slcc,_r-:<,_ ._:.i.a-o tested on i ].<-,,_,,,-._-*-_--,-->_> low- drag airfoil gave l,._t,d e]':os, as hi<: _'s the !ift_ obtained oi% con_yel]Sior._! -_ o ..... and _i-percent-t=._.zk a.!.rfoils _,ith 0.40-.
chord , _-'-_ e ..... __,_n blind and double-slotted f!_N)<, (r.. _ _r_nces 2 and 3). ffh_ increr_.ent in maximmr_ li_'t ":.-_s 1,7!i! for the low- drag airfoil _nd a?proximately 2,00 _'_r ti._ ,,_r._,,,. .... ..,,"_n,. _ _,. _._i airfoils.
With the flap retracted; the douLie-s!otted ±lap tested gave plain-wing section drag coeffic, ients ,,dtl0out the need of folding doors to close g'ips and slo±s. The pitchiog mom_n:_s shovm in figure 5 are or z:,b_,u< lhe s_ne magnitude _rs 7_it, cblng moments obtained for the O. 40- _:_ord .... +-_" -',-_ c'" _en .... an-bli_m, and the double- slotted flaps of rsferences 2 and "a C ONCLUSIOiIZI From the results of the tests, c _ a (; _'-_ 'i,,_;1_ double-- -r.- = l .':', the slotted flap on an NACA op,3-i18, a airfoil, follo_ing conclusions were reached: i. The double-slotted flap tested gave lift coeffi- cients hi,gher than those that have been obtained on Nf}CA
lo_,¢-dragail_."oils w._th plein_ split, or slo_te¢ f.].ap._and _id not
• _ffec_ the low-_r_ G characbr,<ri.qtics -_ _ -- _.._ t,Lo _,in 6 w.Lth th_ fl-o r::_ ,r._::te&.
2. The com])ine, tion tested also offez'ei lore :tr_,g and. moro:_','to lift g_.r the cruising con<_,i__L_;n _d f_izgy low dk<-_.g and hish lift for t%ke-off ,t.n& climb conditions.
Jl,.The lift coeffici@nts obi,',:].i.@d with the 0.30_)-.cherd d<vbie- clott, e_ f]ap wolfe a!uosc as high "_s those obt:.ined w_ th l:_rgcr-chord r@net:i.an-Llind ,::_d doublo-slott ed fl:_ps ,:',n convent,ionul aii'i'c!ls of c,pproximately the same thic!c-_ess "_ the i<-w.-&:¢ag ,iz_foil _(-;s'.,e_.
4. The high lift c_e=flczen,.s_) "" " " _ obtained with _,,,,le _ 0.309-.chord double-sic t god ft_,p _ere ,%,:-co_J_lied by high _i _. ,c_:.!.ng'"-" - mcmc_ts_ _,rhich were c<m,?-.'_r<_ble to those obtained _S.th <:thor high l!.ft devices giv:l;_i_similar L¢,_xJ.mu_._ lift coofflcients.
L_uu_;l,oyHemori%l Aeronautioal -L_.,_;. "'_ ...... ,%_,,e,-y_ i:al,ion _.] A_&v',_<;<F Cc_mg.t,_ee for Aeronautics L_ng!ey Fie].d_ V,%.
I. jacobs; East;Iron N._ A]_bott,, !r_ H., _md _k_vi_s_,n_ kL!ton: Pre.tit,_in'_z.y Low-Drag-Airfoil _(! Flap D-_a fro._ 'lea _s a_,: L_J?[_jo Reynol(<s Numbers ),nd Le_¢ T_trbu].cnce_ t;nd Supp!eme_t.
_b\f',A A .C .:, -_ ._ March 1942 2. Uenzinger_ C_:_i-" J._ end Iimrris_ T.hoBus A.: Pre!Jmi:_ary, l_'in4-qktnnel T-,t _ _ ........ .- Ail'i'::,Jl _:ibh Y_!rlouJ _..e_ =g_tzon of' _ N.A.C.A. _:_0!_ Ar'r_gements c? V_net,2._n.-]31i:_d Flaps }_ACA Rep. No. 6'89_ 19,'_ ....
3. Hal'ris_ Th<::az.s A._ and iRec,tu%t_ ]:s:i.dore G.: _' ,,:-<' . :th ..... unz_el In:,, e s :.:i _zation of N_CA 23012 _ 2302]. _ and 23030 Airfoil; Equippe,d wLL,h 40-_'ercent- Chord [_,ublo ,"<Lotted Flap:_. _'tCA ?lep. ,::,). 723, 19]4!.
I Reproduced [rom best available copy. (_ TABLE !
ORDINATES TOP T_ NACA 65:3-118, a = 1.0, A_KF01L I_tation and ordinates in _ercent of airCoi! chord] Lowel' $_l]:'IEl CO Upper stuff ace Stati on Ord Inato S %ation Ordinate 0 ,) 0 (} .h44 -l_ 298 i. 348 • 566 f .638 .8me i .o3:, -[_ 5o3 i. 18<i i "_o(7 -l. 949 :_.o57 "_4 2. 421 _•Seo 2 _vq -'[" • uD 4.5:10 3.988 5. c,9,) -3.672 -4o 488 7. I_06 "._,].H_ .'7 1 905 !i, _<'.,± " 09_ -5.1&5 14.909 E3I <, 9<:' 5 I<_ -7 (_ , ," 19.9!% -7.036 R _h 1 24°929 r ":1 29• 942 9•034 _4. 956 35.044 -a.Y53 ;J • .)< L) 9.97i 40.0 _, o o4.5:_ 44.9S6 4p.CI!; -r_, ] 48 CI - } -c .C_!
50. OrO0 50.00:) - :.1_97 . -i O!
60.0_4 . _O1 i •_P3 • . .} (i) 65.03 ° 6. 965 -5o935 = 979 -.5.00f 7o.o37 4 qq4 -4 .COS r4. 961 75.039 80 •037 3•788 '79. C63 ':'. 99_ 2.6oi $4 <_ 85. o3_ -1.989 -i .o6,5 90• e,23 8,,. _7'i' - orb 95.012 .65o o. _ , !00. '000 0 1_10 ._ <?
radius = 1.9k: Lea iirlg edge 81opo = 0.042 T_S!,E II CRDINATES FOP, A Oo 309-CHORD DOUBLE-SLOTTI_;D FL_P ON [-Station an£ ordinates in pel-cent oi" airfoil chord] Fore flap Rear flsp Statien Lower _ o_" otc._lOn Lower _bper surface surface B%_fAco "_ 083 .... 75_ mCs -!. 25o -3.1_5 at'9 ,!04 .51;2 - _ ]/) 4 ........ 75 _:'.1 _ 69.167 -2.417 -3,729 76, ,':: 50 .5O0 -2.729 f.
ow, V}'5 -i. 79f_ -4.. 104 77. Og3 i. 167 -3.11:6 3c, <Co -J. 458 -4.333 78,1<!5 i, 771 -.3o_.5o 'P. 000 -. 7o8 -4., 500 79,167 -3.167 -4. £.'38 81. 250 70.833 • !88 -s'. 729 -<- o 708 83,333 7:,_:o 063 1.o5o 2. 583 i, 604 •.]., 86i" ._9s 85.417 " L_H 3 f!. 104 -!, 467 i. 438 8'(o 5oo ,'_', _, 583 i. 958 r_ 7 "D (p, o _f: i. 56_ -i.o58 i. 771 90. o,o 3 g2 • _c_j ' gt.
2,04:7 95. OlS ._5o .65o -. 334 )j .._ F* 0 0 2.292 I00.000 70. 458 2. !_ 17 .... 76,875 .438 a,Reference point for fi_, 2
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3.2 I I I r_ I _D 2.8 i I i I (deR) 2.0 1.6 1.2 o .8 o o ! I/ i I I -.4 -.8 .__ ...... + -1.6 -214- -1 6 Section an_le of attack, a_, deg _gu_e 3.- Bectlon llft characteristics of an NACA 65,3-118 , a = 1.O airfoil with a 0.309c double-slotted flap at various deflections; R, 6,000,000 (ap_roxlmately).
Tests, TOT 399, 235, 252.
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