Document
ACR No. 3120
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f
NA TIONAl ADVISORY COMMITTEE FO R A ER ONA UTICS
ORIGINALLY ISSUED
December 1943 as
Advance Confident1al Report 3120 ~TJND-TUNNEL lNVESTIGATleN OF CeNTROL-SURF ACE CHARACTERISTICS. XV - VARIOUS CONTOUR MODIFICATICNS
OF A 0.30-AIRFOn.-CHORD PLAJN FLAP rn AN NACA
66(215)-014 AIRFOIL
By Paul E. Purser and John M. Riebe .'
~ .
Langley Memorial Aeronautical Laboratory Langley Field, Va.
WASHINGTON NACA WARTIME REPORTS are reprints of papers o riginally issued to provide rapid distribution of advance research results to an authorized group requiring them for the war effort. They were pre- viously held under a security status but are now unclassified. Some of these reports were not tech- nically edited . All have been reproduced without change in order to expedite general ' distribution.
L - 668 NATIOl!TAL ADVISORY COMMITTEE FOR AEROJ.LWTICS ADVAN CE CONF I DENTIAL REPORT i'lnTD-TU.!. TN EL IHVESTIG A TIOn OF CONTEOL-SURFAOE
CHA R AOTER 1ST ros .. XY - VARIOUS OO NTOUR MO DIFIOATIONS
OF A O . 3O-AIR~OIL-CHORD PLAIN FL AP ON AN RACA 66 ( 2 1 5)-014 AIRFOIL By Paul ~ . Purser and John M . Riebe SUMMA RY Force-test me asu re me n ts in two -d imensional fl o w have been r::a de in the NA CA 4- by 6-foot vertical tunne l to . determine the aerodyn am ic ch a r acieristi c s of an lAC!
66( 215 )- 014 airfoil equi pped with true - cor-tour , strai gh t- contour , an d bev eled - trailing-edge flaps havin g chords 30 percent of the a irfoil chord. The results a re p re- sented in the for m of aerodynaaic section char acteris tics for several fl ap deflecti o ns and for a sealed an d un- sealed gap a t the fla p nose .
The slope of the lift curv e , the effectiveness of the flap, and t he negative slopes of the hinge - moment curves gene rally uecreased as the trailing-ed ge anglo waS incr eased , as the gap a t t he fl ap nose was opened, a nd as r oughness was a d ded to t he leading ed g e of the a irfoil .
Th e aerodynamic center of lift c aused by chan g ing angle of attack moved for wa rd a.s the tr a iling-edge angle was incre a sed an d as rou ghn es s was added to the airfoil leadin g ed g e . The aerodynamic center of lift caused by changi ng flap deflection tend ed to move forward when the trailing-edge angle 'iaS incre as ed and , \ ... hen rou gh ness waS added to the airfoil le a di ng edge, tended to move rearward for the true-contour flap, to remain unchanged for the straight - co n tour flap , and to mo ve forw a rd for the b e v eled - t r ailing - edge flap .
The effects of beveled tr a ili ng edges on the chara c- teristics of a p l ain flap on a l ow- d ra g c.irfoil were not significantly different ' from the effe~ts previously noted for similar modifications on conventional air- foils .
I UTRODUCT IOU An extensive two-dimen~ion a l-flow investigation of the aerodynamic section characteristics of airfoils with flaps has been undertaken by the ' NACA to determine the types of f la p a rr angement best suited for use as control surfaces and to supply experimental data for design pur- poses . The investigation has included modificat ions of flap - nose shape , balance length, and gap size on a 9- percent thick lo w-dra.g ai rfoil and on 9- ano _ 15-percent- thick conventional airfoils . Other modifications have included the use of a str a ight-contour flap and a beveled- trailing-edge flap . The results of some of these inves- tigations were reported in references 1 to 5 . Reference 6 has used the trailing-edge a.ngle of the beveled-trail""'" _ in g- edge flap as a basis for correlation .
High - speed airp l anes require the use of airfOil sections 'f/ith low peak pressures, such as lo\v--drag se c- ti ons , for tail su r fa.ces to alleviate the danger of shock stall . I n order to extend airfoil p rofile a lt era tions to 10 "' J'-drag airfoil contours, tests haOle been made of the NACA 66(215)-014 airfoil equipped with true-contour, flat-contour , and beveled-trailing-edge flaps . Through- out the p resent pape r , the flap having the same contour as the trai li ng edge of the basic airfoil will be re- ferred to as the true-co n tour flap , the flap having a contour formed by straight l ines drawn from the flap nose arc to the trai li ng ed g e as the straight-contour fla~, and the flap , formed by thickening and beveling the trail- ing-edge po rtion of a straight-contour flap as the beveled - trailing-edge flap .
APPARATUS AND MODEL ..
The tests were made in the NACA 4- by 6- foot verti- cal tunnel described in reference 7 . Tho test section
-- ---, - -----"~---- -~ --'
of this tunnel has ~een converted from the original open , circular, 5-foot diameter jet to a closed, rec- tangular, 4- by 6-foot throat for force tests of models in two-d imensiona l flow . A three-component balance system has been installed in the tunnel to measure lift, drag, and pitching moments. The hinge moments of the f lap wer e me asu red from a J3pecial torque-rod balance built into the model.
The 2-foot - chord by 4-foot-span model ( fig. 1) was bui lt of laminated mahogany to the NACA 66(215)-014
profile . (See table I.) The airfoil was equipped with
a true-contour flap and a beveled-trailing~dge flap with chords 30 percent of the airfoil chord (0.30c).
The cusp of the true-contour flap was filled in with plasticine to form the straight-contour flap used in part of the tests. The nose radius of each flap was approxiBately one-half the airfoil thickness at the flap hinge axis , and t.1e flap gap was 0. 002c. For the sealed- gap tests, a rubber sheet was c onnected betveen tho nose of the flap and the airfoil .
The model , ·,hen mounted in the tunnel, completely spanned the test section and was attached to the balance frame by torque tubes that extended through the sides of the tunnel. mhe angle of attack waS set from outside the tunnel by rotating the torque tubes with an electric dr ive.
TESTS The tests were made at dynamic pressures of 11.25 and 1 5 .0 0 pounds per square foot, which correspond, respectively , to ~ irspeeds of about 66 and 76 ~ilos per hour at standard sea -l eval conditions. Tho effective Reynoaas numbers of the tests were approximately 2,400,000 and 2,760 , 000 . The ef fective Rey~olds number is th e product of the test Reynolds nunber and the tur- bulence factor, which is 1. 93 for the 4- by 6-foot ver- t ic al tunnel .
The three flap contours tested were set at flap de- flections from 0 to 30 ° in increments to 5°, including an C additiona l deflection of 2 , with the gap both sealed und unsealed. For each flap setting, the values of lift, dr ag pitching moment , and flap hin~e moment were read J throughout the angle-o ' f-attac k range f ro m negative , stall to pos itive stall . .All r eadings were t aken at , i:1cr err:e n ts of angle of attack o f 20 . e xce pt ne a r th e ' stall ¥ h er e t he increment was r ed uced to 10.
Force test ,s \ -16 1'S a l so made at an ' an g l o of attack 0 0 0 of 0 , at f l ap d ~ flectiolls from 0 to 30 in increments of 5 0 (i nc luding an ad ditional deflection of 2°) in or dor to p ro v ide a ch ec k for th e tests previously ~en tio nod and to obtain da t a for BBasuring so n e of the pa r umet er s wi thout cross- pl otti ng .
I n o rder to det e r m ine th e effect of u fixed transi - ti on l) oin t nea r the l eadi ng e dge on the aerodyn31 u ic c har a c t e r istics , force tests were also ma de with surface r oughness extending ba c k app ro ximately 2 . 7 inches (0.11 ) fr oD th e ai r f oil leading edge . The roughness consisted of c a rbor undum pa rticles of t he size and distributi o n r efer re d to as s t anda r d rou g h ness in re ference 8 .
Th e a ccuracy of the data is indicated by the devia - ti on from zero of the lif t and moment coefficients a t an ang le 0: a ttack of 0 with t he flap n eu tr a l . The maximum error in ef fe ctive ang l e of at t ac k at zero lift ap p e a red to be a bout ±O . 2°. F l ap deflections wer e se t to within ±O . 2° . Tunnel c orre cti ons , ex~orim~ntally de - termi n ed in t he 4- b y 6- foot vertic a l tunnel , were ap p lied only to lift. ~he h in ge moments are p robably sli ;ht l y hi g her t han wo uld be o btained in free a ir a nd , c onsequent ly, th e v alues p r esented are co nsidered con- serYative . ( See ref e rence 9 . ) The increments of drag sh ou l d be re asona b ly independent of tunnel effect, a l- th ou g h t he ab sblute va l ues a re subject to unknown tunnel and tUrbu lel'lce correcti ons . ' SYMBOLS The coeffi cien ts and symbols used in this paper are de fined as follows: c~ a irfoi ,l secti on l ift coefficient (t/g , c) cd a {i fo il sictio n ~ rdfile ~r ag coefficient ' , (d o!qc ) o cm a irfoil sectio n p itc h in g- moment coe fficient about q u a rter-c hord point of ai r foi l ( m/q c )
Chf flap section hin g e-m~ment coefficient (h f/ 2)
q cf t airfoil section lift do airfoil seotion profi~e dra g m airfoil section p itch { ng moment about qua rt er- chord point of airfoil hf flap section hinge. moment c chord of basic airfoi~ with flap neutral Cf flap chord q dynamic pressu re and.
~o an g le of att a ck f~r airfoil of infinite aspect rat i 0, de. gr e e s Sf fla p deflention with respec t to ai rfoil, degrees ¢ tr a il inG edge allg10 ,.- included betve en sid as wh i ch form trailing edGe of flap, deerees.
Re affective Reynolds number PRESENTATION OF ~ESULTS ThG a erodynamic section characteris tics of the NAOA 66( 2 15)-014 ai rfoil for a gap of 0.002c and for the gap sealed ar e pres ented in figures 2 and 3, res p ectively, for the 0.30c true-co~~our fla p , i n figures 4 and 5, res p ectivel y , fer the 0.30c straight-con tour flap, and in f i g ure ::; 6 and 7, rt:'. spe.cti'V'el y , for the 0.30c bevelEld- trailing-o.dge flap.
A C0 In l) arison of the ae ro.d ynamic se ction characteris- tic s at zer ·o flap deflection with s4100th and roughen.ed le a ding edge for the true-contour, st r aight -co ntour , and beveled - tr a ili ng-e dge flaps is shor,.rn i!l figure 8 with a gap of 0 . 002 c and in figure 9 with the gap se a led. The variation of tho aerodynamic section c ha r a cteri stics with flap deflection for the true contour, straight-contour, and beveled - trailing-edge flaps with a sm o oth a nd r ou g hene c L le ading e dg e at zero angle of 'at t a c k is shown in figures 10 and 11 wit h a gap of 0.002e and with the gap sealed, res pe ctively .
Increments of section p rofile- drag coefficient cau sed by deflecting the flaps are given in fi g ure 12 for the true - contour flap, in fi gure 13 for the st r ai Gh t-- contour flap , and in figure 1 4 fo r the beveled-trniling- edge flap . Fi gu re 1 5 shows the effect of Reynolds nu m ber on the ai rfoil \vith the tr . ue-co ntour fla p a t zel~O deflec- tion with the gap sealed .
The flap ninge- m oment p araneters (OChf/ d CC t ~f and
( 0 c 11 f / 0 (; f ) a,o ar e s hOlm i n f r gu r e 1 6 as f Ul'" C t ion S 0 f the
tr ai li ng - edge ang le fo r a gap of 0 . 002 c and for the g ap sealed with a smooth an d roughened leadin g ed g e . The various pa r ahl eters for the true-contour , straight -c ontour , and b eveled-trailing-edge f l aps , which are p re sented for co mparison in table II , a r e the values of slopeR m easured at an an ~ le of a tt a c k and a flap deflection of 0° .
DISCUSSIO N OF RESULTS Lift Q~~~.ral sha:£.s?_Q!_lift Qur:!':.~.- ':2he lift curves of the straight -c on tour or beve l ed -tr ailing-ed g e f l aps for various f l ap defloctions and for the gap open ( figs . 4 and 6 ) or for the gap closed (fi g s , 5 and 7) have the s ame general sh ape as th e lift curves of th e true-contour fl ap fo r t he gap o pe n (fi g . 2 ) or for the g ap closed (fi g . 3). The gap-open and gap - sealed co n ditio n s have different f lap deflection ran geB where the lift curves appro a ch the li nea r conditions . For the ga p - open condi- ti ons , some non line ari l y occurs for the 1 0 ° and 15 flap de f l e cti ons ; whe rea s , fo r the gap -se a l ed condition, this nonli nea rit y is most noticeable for the 15 a nd 20 ° flap defl e ct ion s • As the tr ail ing-e ' dge angl e in cr eas es, the range of flap deflections ov~r which this nonlinearity occurs tends to become la.~ger when , the gap is sealed and to remain the Same when the gap is open.
T~e angle of attack at which the airfoil stalled tended to increase slightly as the trailing-edge angle increased with the gap open but was approximately the
sa ~G with the gap sealed. A comparison of figures 2 and
3 with the data of reference 1 indicates that the lift curves for var ious deflections of the true-contour flap for both the sealed and unsealed gap on the JACA 66(215)-014 airfoil are ore linear and indicate stall at ' reater angles of attack than those of the NACA 66-009 airfoil .
~1~Ee of lift curves.- The slope of the lift curve
(0 c t /O(t,~f for th e true-cant our fl ap 1. .... as lar ger than
that for the st r aight -co ntour or beveled-trailing-edge flap 1,dth the sealed or unsealed gap. (See table II.)
The decrease in (OCt!0Oo)O-f' for the three flap contours " / ...
that occurred with increasi ng trailing-ed ge angle nay be attributed to the increased thic{ness of the after por- ti on of the airfoil , \·Jhic11 caused an increased devia tion in flow from the theoretical flow for thin airfoils. A decrea se in (OCL/O(t,~ 6f also occurred for the three flap contours when the gap fas unsealed . This trend agrees qualitat ively with the r esults for tho NACA OOO~t 0015, and 66-009 airfoils (references 1 to 5) .
~~!~~~ven~~!~lap .- The effectiven o ss of the
fla ps (d::t /06r )CL was £,; reatest for the true -conto ur flap
o and was approximately the s am e with the gap both sealed and unsealed. As the trailing-edGe an~le increased, the effect~veness decreased ; and unsealing the gup further red u ce d the flap effe ctiveness (table II).
With the gap unsealed , a ll flaps tested were ef- fective in p roduci ng positive i_crements of lift at all positive fla~ deflectio~s within tho unstalled ran6e of angle of a ttack. The flap effectiveness at zero angle of attack and small flap deflections was greater with the gap sealed than i,lith t:1.e gap unsealed, -but tho increnents of lift for the high flap defl e cti ons with t~e eap sealed were very small or zero in part of the negative anole- of-attac k range. Although a drop i n effectiveness occurred a t high flap deflections at negativ e angles of attack, the drop in effectiveness wi t h flap deflection at the positive a ngle of attack was not so p rono unced for the RACA 66(215)-014 airfoil as for · the NACA 6 & - 009 airfoil (reference 1) and 0015 airfoi l (refe rence 5) .
Slope of lift , curves ",ith controls free .- The param- eter -( ~c :-/~~~-~O (table II) is a measure of control- ': ~ O )Oh , f free st ub ~lity . Th o slo pe of the control-free lift curvo w as less than that of the control-fi xed lift curvo for the true-contour fl ap with the gap oither sealed or un- sealed . For the straight-contour flap the slope of the lift curve with control free waS smaller than with co n trol f i x ed for the sealed gap; "lhe re a. s no c hang e oc cu rro d for the op en gap . The s l~pe of tLe control- fre o lift curve ' waS larger tha~ that of tho control-fixed 1 ift curv c for th e b ev 0 1 ed-tra i 1 ing-cd. ge f l ap ', bo in ,> greater when tho gap waS un~ealcd t hnn ~hon se a led. Com- p a rison of tho data for tho throe flap contours s ho~s an increas e in ( ocdOo:.~Chf:= 0 vli th trailing-edge angle .
It should bo noted that these statements arc basod on slo re values measured over a small a ngul a r range and the ir use is therefore l imited t o stability c alcu l ations and ot he r ap~li cati o ns wh ich a re c onc erned only w ith s ma ll ch anges in angle of attack and deflectioh .
~!fe~!_~~lea~in~=edge_£o~~hness.- The eff oct of rou ghness on the airfo il leading e dge was to decrease the slope of the airfo il lift c~rves and the ef fcctive~ ness of the true-contour, straight-contour, ~nd bev o led- trailing-edge flaps for the gap both sealed and unsealed .
(So e table II.) The presence of rou ghn os s on the airfoil lea ding edge &id not ch ange th o tendency of the open gap and the inc reased trailing-edge angle to reduco the slope of the airfoil lift curve and the flap effectiveness.
•
With controls free the Sl~P0S of tho li f t curves we re lar g er with a roughened leading edgo than wi t~ a smooth ' lo aeling od.ge in all cases except that of the true -cont our flap with gap seal ed and tho bev 81 ed-trail ing-edge flap with gap unsealed. For the bevcled-trailing-edge flap with gap unse aled tho presence of roughness resulted in an un'staole condition oec ause ooth (OChf/oa,~Ot and (ochf/08f)a, were positive .
o The lift coefficient increa sed relatively linearly with the flap deflections aoove 1 0 with either smooth or roughenod le ad - ing edge when the gap was sealed or un- sealed (figs. ' 10 and 11) . The general effect of rough- ness , however, was to r educe the l ift coefficient at a given flap deflection and to r educe the maximum lift coeffici~nt.
Effect of Re~olds numoor .- An increase in eff~ctivc Reynolds n1.."..mbe r from app ro ximately 2,400,000 to 2,760,000 increased the maximum lift coefficient fron 1.06 to 1.13 at positiv e angles of attack and from -1. 01 to -1.20 at negative angles of atta c k for the NACA 66(215)-014 air - foil \dth a true-contour flap at Of = 0 dth the gap sealed. (See fig . 15 . ) Increasing the effective Reynolds
numoer caused a slight increase in the slope 0: the lift
curve . The differences in the angles of attack for zero lift for the two tests is within the li mits noted previ ..... ·_ olisly under "Tests" and i s p roo ab ly the result of errors in setting the angle of attack or flap deflection.
Hinge Moment of Flap Q~ne~a~~hap~_£~£1nge - moment curves.- ~he curves of flap section hinge moment plotted against angle of attack (figs . 2 to 7) were not unusual except for the oreaks that occurred at the intermedi ate and high flap deflections . These oreaks , generally larger with the gap sealed than with the gap unsealed, were probably the result of flo ',1 sep a ration over the flap.
~~~pe~f hing~~m~~~nt - c~~~~ .- The hingo-~oment parameters for the three flap contours with the gap sealod and unsealed are given in table II. Because of the nonlineari t y of the hinge - moment curve~ over most of the ang le-of-attack range, tho parameter ~ .. OChf/OClt~of o 0
waS measured at Bf = 0 and 0,0 = 0 over the linear
range previously ~ent i oned . Although this rango is smal l, these values can be uEed for comparing the throe fl~p contours an d for stability com p ut a tions; however, for a co mp lete comparison the entire sot of hin g e~moment curvos mu st be t aken in to considerati on .
The L'1 easured slope (OChf/oa. o~f "raS zero for the strai gh t-contour flap with tho gap unseale d ; howevor, for tho gap both sealed and unsealed, ( :JChf/oa. O \'f "ras negative for:the true-contour flap ai1d was pos itive, sho\dng an ove rb alance , for the beveled-tr a ilin g- edge flap. ( See figs . 8 and 9 .) T he value ( o chf/ o a O )Of \;raS mo re :9 0sitive for the flaps with the l a r ge r tr ai l in&,'- edge angles . This trend ag ree s qualit . atively ", ith the d a t a of reference 4 , but the actual value of the chan g e is l a r ge r than that indi c ated . by the curves of refer- ence 6 .
Va lues of the p a ram eter (OChf/ dOf )a.o (fi gs . 10 and 11) were measured a t flap deflections from 0° to 50 because of the nonlinearity of the flap section hinge- moment curves throu gho ut the f l ap deflection range. An i ncrease in t r ai ling-ed ge angle produces a decrease in the negativ e value of (dCh f/oof) for the gap sealed a o or un s ealed (t able II) . T hi s trend also ' agrees with the data of re f erence 4 but the actual values a re again l arger than those indicated by the curves of reference 6.
Effect of leadi ng -ed ge r o~hnes~.- The effect of l eading edge roughness on the variation of (ochf/ o aJOf and ( o chn/dOf)a. \dth trailing-edge ang le and gap con- I 0 diti on fo r tho 0 . 30c flaps on the NACA 66( 215) -014 a ir- foil (fi g . 16) was to make both (OChf/ Oa.ok an d f \ OC hf/O .O f)a.a rllore positive . The presence o f leading- edge rou~hness diQ not alter t he general tendency of
( OChf/Oa.~5 f and ( OChf/OOf)a o to become mo r e positive
with increases in tr a ili ng -ed ge angle and "dth unseal- i ng the g ap .
Effect of Reyno lds number . - An increase in effectiv~ Rey no l ds numbe r from approximately 2 ,400, 000 t o 2,760,000 sli&htly in cr eased the negative value of ( OChf/da.~t - - --- o
for the true-contour flap at of = 0 with tho gap
sealed (fig. 15). The difference in the values of tho hinge-moment coefficient at ~o:: 0° probably resulted from errors in setting the angle of attack and flap de- flection.
Pitching I, foment The values of the parameters (ocm/Oc~)a, and o ( 0 cm /0 c ~ ) 0 ~, s h o ... m in t a. b 1 e I I , g i vet h e po sit ion 0 f the I aerodynamic center with rospect to the quarter-chord point. When the lift was varied by changing the angle of attack at a fla.p deflection of 0 , the aerodynamic center of t h e smooth airfoil with a scaled gap waS at 0.25c for the t r ue-contour flap, 0.22c for the straight - contour flap, and 0 . 20e for the beveled trailing-edge flap. This trend agrees qualitativ e l y with the results in reference 4. With roughness on " the leading edge, tho aerodynamic center moved slightly forward to 0 . 24c for the tru&-contour flap , to 0 . 21c for tho straight-contour flas
:and: , tct :- 0 l~a .... for tho bevel~d~traili ng-ed g e £la1") . Un-
sealing the gap generally had little effect on the position of the aerodynamic center. IncreaSing the ef~ fective Reynolds number had very litt le effect on the aeroclynaraic center of the ai rfoil "lith the sealed true- contour flap at of:: 0 (fig. 15).
The following table g ives the ~ ositi on of the asro- dynanic center of lift due to flap deflection:
-----,.----------------------- - --------- --- -
Aerodynamic~e nter True-contour Straight-contour Beveled-trailing~ Leading flap flap edge flap edge r-O·-.-0--0-2-a-,-S-e-a-l-e-d---~0- . -O-0-2-C-- ~i s-e-a --l-e-d--~---O-- .-O-O -z-c--li--s-~~-l--ed gap gap gap gap gap gap Smooth 0 . 43c 0.4lc II · 0.43c 0.42c c.40a c Io.4lc- Rough .46c .44c .43c .42c .38c .38c __ ~~ __ ~ ________ ~ __ . ____ -L~ ____ ~ __________ _L__ "_______ _ __ llith roughl'l.ess on the leading edge, the a erodyn amic center of lift c aused by flap deflection moved r earward about 0 . 03c for the true - contour flap, remained un- changed for the straight-contour fl ap , RDd ~o~ed 0.02c to 0 . 03c forward for ' the beve l ed-tr n. iling-ed ge flap .
The pos ition of the aerodynamic center of lift caused by flap deflections is a function of the aspect ratio (ref- erence 10) and moves toward the , trailing edge as the aspect ratio decreases . It can be seen t hat , if the aerodyna m ic - cente r p ositi on s are plotted against ( Q c h f / 0 a, 0)8 f an d ( 0 c h f /0 8 f ) 0,0 the rei sag en era 1 t r end for the a erodynamic centers to move forward as the slopes o~ the hinge - moment curves beco me mo r e positive .
Drag Because the turbulence of the 4-- by 6-foot vertical tu nne l E'lad o it impossible for t:h.e lo ~r-d ra g condition to be r ealized on t he NACA 6 6 (2 1 5)-014 ai rf oil and because of the unknown tunnel corr e ctio n , the me asured values of drag can n ot be considered absolute and are n ot presented in the present re po rt . T he incr emen t al values, however, should be relatively inde pen dent of tunnel effect, and, therefore , increments of profile drag caused by def le c- tio n of the true-contour , straight-contour , and bevoled- trailing-edge flaps a ro sho1.·Jn in figures 12 , 13, and 14, res p ectively . These increments we re determined by de- ducting the dr ag 6oeffi&i~nt ~ of t he a irfoil with the fla p neut ral from the drag coefficient 'ltlith the flap de- flected , i'lith all ot"ler factors remaining constant . ...: c, :;:- F J :~
For a ll three flap contours at o,g = 0 and at
positive flap deflections above 12 " the increments of dra g coef~icient were larger with the gap unsealed than with the gap sealed .
C ompa rison of figures 12 to 14 indicates that de- flecting the true - contour flap generally c aused b~e l a rgest Ll c2'ement of d.rag ; \'lhereas deflect ing the beveled- tr a iling--edge flap caused Jlihe le as t increment . iihen the data of figures 12 to 14 were compared on an equal lift- increment basis rather than on an equal flap-deflection b as is , the true - contour flap still produ ced larger drag increments than the other flaps over a ran ge of about 0 . 4 in ~cl ' but the difference in the increments was much les s than shown in the fi gures.
CONCLUSIONS Tests have been made of tl e NAOA 66(215)-014 air- foil eq.uipped uith true-contour, straight-contour, and be--eled-trailing-ed e flaps having chords equal to 30 percent of the airfoi l chord. The effects that incroas- in G the tr a iling-ed.ge angle had in decreaning the lift o ve r the airfoil trailing edge were not significantly different from t he effe cts previously noted on conven- tional airfoils and are contained in the following con- clu sions : 1 . The s lope of the ai rfo il lift curve was lar gest vdth tho scaled true-contour flap and. decrcasad as the gap ~, t the flap nose \vaS opened~ as the trailing-edoo angle was increased , and as rou ~hness was added to tho airfoil leading edge.
2. Tho sloue of the lift curve with controls free (zer o flap ~ing~ moment ) gone raJly increasod as the tr3.il -:'::.('"'-o dgc anglo irJ.creased aL1 as roug~ncss i'TaS 3-d(10d to the u irfoil loading edge . The effect of the gap at tho i.-' ge line varied with trailing-odge angle and \'lith the adCltion of ro~g~noss to t ~Q airfoil leadin~ edge.
0 . The effectiveness of the flap in producing lift was ~reates t with t~e true - contour flap and generally dec~eased ~s the g3.p at the flap nose was opened, as the trailin6 ed s e an~le was increased, and as roughness was added to the airiol l leadin g edge.
4 . T~e slope of the curves of hinge mOLent plotted ~bai~st anGle of attack at a flap deflection of 0 and small ~ngles of attac~ was approximately zero for the straiGht-contour flap, negative for t ~e true-contour flap, ~nd ~ositive for the beveled-trailing-cdge flap.
The negative slopes of the curves of hingemor.ient p lot ted agai:lst flal) deflection for all three flap contours de- cre::1sed as the trailing -ed ge anGle increased, as roughness was added to the leading edge of the airfoil , and, for the straig~'lt-contour und be ' eled - trailing-od{;e flaps, as the eap at the flap nose was unsea l ed.
5 . When the lift was varied by changing the ang l o of attack a t zero fl 3.1) deflection , the aerodynamic center of the smooth airfoi l with a sealed g:1p moyed fo r vlBrd as the tr ai l i ng - edge ang l e W i:'.s iner eas ed. U ns Gal ing t he ga:9 L .. d l i ttle ef f ect on the ao r odyl1anic centor; whereas t ho ~dd iti on 0: le ading - edge rou ghn e ss moved tho aero - d yn3.Lii c c on t er forward 1 or 2 per cent of t lJ.e a irfoil c h ord . At co~stant ang le of attack the aerodYl1D.nic centor of lift c aused by fl ap d e flection a l s o te_de d to move foru a rd as t ho tr e. il inf, "-ed go ang lo vIaS increa sed .
Unsealing t he gap or adding ro ug.ness at the a irfoil l ca d int; ed g e t ended to movo the aerod n a:n ic c ente r r <;ia p- \<rard for tho tru e -c ontou. r fl p and for\ v ard for the b cveleQ -tr a ilin~edgo fla~ .
L anb l ey · r.eno rial Aeron au tic a l L abo r a t o r ~T , H ~t i on~ l A dv isory Co m~ itt eo for Aeronattics L~ng le y Fi old , Va.
REFE~ElijCES 1. Gil J is, C 1 a r 0 n c e L ., an d L 0 cl c-.V' 0 0 1 , V 0 r n a 1' a.. E .: Win d- ~ u~nol In ves ti gat i on of C ont r ol -Surf a c o C hn 1' a ct er - isti c G. XIII - V" r ious Flap Over . <.:.lL.,8 Used t·rith h ~O-Percent -C ho ra Fl ap on an AOA 66 - 009 Airfoil .
~AC\ ACE 10 . 3G20 , J uly 1 943 .
2 . So a r e , Richard I . , an d Ho ~ga r d , H . Pn ge , J~ w: W~nd ~ unn cl In ves ti g . t i 0n o f Co ntro l-Surf a c o Ch a r a cter - i::;ti c 8 . II - A L a q ;e J crod ynr'J.1 ic Ba l al;. ce of V [' . ri ou s 3 0 80 Shape s ith a 30-Perce nt- C ho rd Fla p on an 3ACA 0009 Airfoil . NACA A . R . R. , A ug , 1 94 1 .
3 . Soa r s , Rich a rd 1. , and Gillis , Cl a re _ _ ce L .: ifi nd - Tu.n Je l Investi ga tion o~ C ont r o l-Surf ace Character - istics . VIII - A L a r eo A erodynamic Balance of Two ,i. - o se Shapes Used. t'lith a 30-P o rcont-Cho . d Fl ap on a~ ~ ~O~ 00 15 ~irf oi l . RACA ~ . R . R ., J uly 1 942 .
4 . Jono s , Rotort T ., and ~ \.L'l e s , r: ilton B . , r .: ~ 'i n d Tun ~e l Invcsti Ga tio~ of Oontr o l- S urface Ch a r o. ct o r- isti c s . V - The Usc of a Bevo l e d Tr a ili nG Ed g o to Roduco the HL lge -I o: :! E.'nt o f a Control Surf a co .
~~C~ A. R . R ., ~ Q rch 1942 .
-- ~--~ '---- "- -- -- -- 5. Hoggard , H. Pa ge , Jr.: Wind-Tu nn el Investi ga tion of Co nt rol-Surface :-; C haracteris ti cs. X - A 30-Percent- Chord Plain Flap with St~aight Conto u r on the NA CA 001 5 Airfoil. I-TACA A, R,R" Sept. 1942.
Purs e ', Paul E., and Gill i s, Cl arence L. : Preli minary 6 .
Co rre l a tion 01 the Effects of Bevel e d Trailin g Edges on the Hinge - Mom ent Characteris t ics of Control Sur - fac e s. NA CA CB No , 3E14; ~ay 1 943 .
7 • Vi e n z i n t;; e r , Car 1 J., an d li a r r is, Tho ma s A . : The Ve r tic a 1 Win d Tunnel of the Nat ion al Advisory Com m itte e for Aeronautics, Rep . No , 387 , i iJ',a OA, 1 93 1.
8. J acoDs, East man N . , A bb ott, Ira H " a nc1 Dav i dson, iVlilton : Sup p l emen t (100 e-le af ) to NACA Advan c e Con f i den tial R epo rt , Prtliminaq. :::"ow- D :'a b - ~ \.irfoil .?,nd :b'lap Dn.ta fr om Tests at Lar ge Reyn ol ds Numbers and Low Turbule n ce.
fA CA , 'ja rch 19 42 .
9, Sears , Richard I. : W ind-Tu nne Data on t~e Aerody nam ic C ha~a et evis ti s of Airplane Control Surfaces , ~ACA ;"OR 1IJo. 3L 08 ; De c. 1943 .
10, Arre s , : ilt.on E ., Jr., and S ee.rs , Eieha d I ,: Deter - minat ion of Control-Surfac e Charac t eristics f r om ~AC~ Pl a i n -Fl ap and Ta b Da t a , Rep . Uo , 7 21 , N~ CA , 19 41 .
TABLE I ORDINATES FOR KACA £6 ( 315)-014 AI R~OI L [st a t i ons a nd ordinates in percent of airfoil c h ord] - - :;,0\,19 r Station Upper
I
i surface surface I
I
0 0 0 . 5 1 . 036 -1 . 0 36 . 75 1 . 2.40 -1 . 240 1 . 25 1 . 535 -l . 535 2 . 5 2 . 080 -2 . 080 5 . 0 2 . 880 - 2 . 88 0 3 . 506 - ?i . 5 C6 7 . 5
I
10 1 . 04: 8 - 4 . 048
I
1 5 4 . 904 - 4 . 904 20 5 . 566 - -G . 566
I
I 6 . 0 81 -6 . 081
I
I
30 6 . 470 -(; . 470 i 30 6 . 748 - 0 . '7 48 6 . ~20 - 6 . 9,:.,0
I
oar 45 6 . 995 . ... oJ D -
I
I 6 . 962 - G. 962
I
5::> 6 . 8 07 - 6 . 807 6 0 6 . 497 -6 . 497
I
65 5 . 978 -5 . 978 I 70 5 . 224 - 5 . 224 75 4.342 - 4 . 342 80 3 . 3 7 - 3 . 375 r 2 . 3 75 8 - 2 . 375 90 1.389 - 1 , 3 89 95 . 523 -. 523 100 . 095 - . 095 radi us : L.E . 1 . :2 06 TABLE II PARA ETER VALUES OF FLAPS OF 0 . 30c TESTED co \0 ON THE NACA 66(215) - 014 AIRFOIL IN THE
J
NACA 4- BY 6-FOOT VERTICAL TUNNEL - l' ru e- Straight- Beveled- contour con tour t rai 1 ing- Leading- .
flap; flap; edf,e Para.m flap; eters edge =
p -8 0
19.3 rfJ =
P = 30
surface Gap , Ga .p , Crap , I Ga]" :rar, Ga9 , sealed O. 002 c se a 1 eel
I o. 002
c sealed 0 .
008c - 0 58 ,[smooth - 0 . 59 -0.
-0.58 re 56 -0 . 46
. 53
( oao '00f) l Rough - .
- . 53 -.55 -. 46 -- . 48 -.42 cl
J~mooth
• 098 • 094 • 090 • 095 .079 • 084
(""1 --- )
aa
l Rcugh . 0
• 088 .0 8 1 %f • 084 . 080 • 077 ( I Smooth • 064 • 061 • 087 • 085 . 282 • 18°
(oct
- j
L Rough
oa o/ c ~f :..: -·
r. . 059
Dlver • 062 - • 091 . 358 • 091 gent ( Smooth • 005 • . 032 003 • 023 • 045 m\ • 058
(oc
)
~(.q)o
L Rough
' . • 013 . 038 f • 011 • 041 • 0£2 • 062 -.1 60 -.1 83 -.17 2 -.184 -.159 -.150
f
ooth
(::~)
a Rough -.1 89 o -. 213 - . 174,- . 180 -.122 -.125 Jsmooth - . 0081 - .
008 8 -. 0005 0 ( CChf) . 0049 .Oe56 oc'o 0: 1.. Rough - . 0079 -. 0077 . 0008 • 0010 . . 0057 .0058
(JCh
'\
-. 0134 - . 0146 - . 0076 - .
\---.! tmooth 0059 - . 0022
) -. 0010
cO f Rough -.0122 a . -. 0140 -. 0052 -.00 - 36 -. 0008 • ..., 0010 .
"""T"l
z » ('"") »
t.5
~
k-
I
Cf
line
',20
~~
ht
flap
_30e
airfoil.
Stroi9
.
.30c
··
edge
Y
-
i-"
R=.052c i
-~
fo
Q
trailing
', k'
(2/5)-0'4-
-
c
_
'"7=
p
/ap-_
a
f
.
= -"...r~-.;:"
'9
:
icene 8eve/ed
___
L~
NACA
.002c
.
rYost
,4
··contour
~
/ on
3" ./ -. --i
airfoil
9.
true
J
--
-
(/):.:
--
.
ubber
5ea/
tested
with
::.24" - ~~ .
-
- R .
c
laps
0c
(215)
f
flap
Airfoil
of
our
Stroi9ht,~
Cont ~.4(.
NACA
------ -
t
Detai/5
-
I.
5trai9h
Fl9ure
.002c 9ap
,.c
_
l
F ',~ f \ ) , j t.-J .! k.
c O: i >'I. ,
H
fbi~Iif '"+·· 1 '+"'I -'·· \-- 1 -' .
•. W!
",' . ", I : Il II--hl..
,: i . 1\ . 1_ , . "'"JX-: ,i· .; H': CJ l "'d 1 _+ . ~~. ., I ··J - . I -I -I -f-- -,.!--c i ±-l :~~. · : E~ ~ ± . d Iti ",io: ! . ' ,'hJ .1" .
':p ; f ~·~ f- -!·~
·f
~:::c 1- --, - T h ···· I ··- l'~ , I.'
, \ ; ~ _~ _ . eL- I NJ.lIOUl j . '
~ '.' ,w 'rr . ~r~
l I I "I I "C , "( I '{ H:;: \',,' f .:::· • :1:': .~~~: h ~ fiI ·!·:'::W I~" }g. l : I' ~ ;:;.
. .:,,:.:' \::·t ::ii:,I T :: .
: ..
; : , .!.
;,if:
.1
.. iii 11] I....
( -:;:;;;, " ""'IX . ~ I If , ~ I .• h'l" " :. Vi ...
I~"' ~ >1"·:·:::·, t ! · I' I"' ; :.,, · ·Ii , ~i'Y ~ Hi 1 ..1:,', ..
•• ' < i~" i': .. it:·y"
•
" . ·iI· .::: s.
r= :c~ .";I""",,,Qi .·.·-.b,c, •.
~~ 'Efij; :," .1''', ,,~ .. 1 ",.1:" !~, .: ',,:r:: ....
t""rr: ~ .
• : ..
I
•