1、NATIONAL ADVISORY COMMITTEEFOR AERONAUTICS -=.TECHNICAL NOTENo. 1327i 16 194/ ! :,. -WIND -TUNNEL INVESTIGATION OF THE EFFECT OF POWERAND FLAPS ON THE STATIC LATERAL CHARACTERISTICSOF A SINGLE -ENGINE LOW-*G AIRPLANE MODELBy Vito Tamburello and Joseph WeilLangley Memorial Aeronautical LaboratoryLang
2、ley Field, Va.WashingtonJune 1947mz A LIBwY -LANGLEYMEMO= iRONAmM ,.:.,LTORyLandeYField,m-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-s.-L - .IWTIONAL ADVISORY COMMITTEE FOR AERONAUTICSTECHNICAL NOTE NO. 1327WIND -TUNNEL INVESTIGATION OF TKE EFFE
3、CT OF POWERAND FLAPS ON THE STATIC LATERAL CHARACTERISTICSOF A SGIW4ZNGINE LOWWING AIRPIANE MODELBy Vito Tamburello and-Joseph Well3UMMARYAs part of a comprehensive investigation of the.effect of power, flaps, and wing position on staticstability, tests were made in the Langley 7- by 10-foottunnel t
4、o determine the lateral-stability characteristicswwith and without power of a model of a typical lowwing single-engine airplane with flaps neutral, with a “full-span single.slotted flap, and with a full-span doubleslotted flap.,. Power decreased the dihedral effect regardless- Of-flap condition, and
5、 the double-slotted-flap configur+tion showed the most marked decrease. The usual effect. of power in increasing the directional stability wasalso shown. Deflection of the single slotted flapproduced negative dihedral effect, but increased the -directional stability. The effects of deflecting thedou
6、ble slotted flap were erratic and marked changes inboth effective dihedral.and directional stabilityoccurred. The addition of the tail surfaces alwayscontributed directional stability and generally producedpositive dihedral effect,INTRODUCTIONRecent trends in aeronautics have been toward thedevelopm
7、ent of airplanes with increased power andincreased wing loadings, The realization of theseadvances, however, has introduced new and seriousproblems in the stability and control characteristicsof the airplane. Increased engine power has been shownProvided by IHSNot for ResaleNo reproduction or networ
8、king permitted without license from IHS-,-,-2 NACA TN No. 1327to produce large slipstream effects and trim changes,whereas increased wing loadings have presented theproblem of obtaining higher lifi for take-off andlanding without impairing stability and control.A comprehensive investi ation was unde
9、rtaken atfthe Langley Laboratory in 19 1 to determine the effectsof power, full-span flaps, aridthe vertical position ofthe wing on the stability and control characteristics ofa model ofa typical single-engine airplane. The presentwork includes the lateral-stability and control charac-teristics of t
10、he model as a low-wing airplane, Theresults of the longitudinal-stability investigation withthe model as a low-wing airplane are presented inreference 1.COEFFICIENTS AND SYMBOLSThe results of the tests are presented as standardNACA coefficients of forces and moments, Rolling-,yawing-, and pitching+n
11、oment coefficients are givenabout the center+f-gravity location shown in figure 1(26.7 percent of the mean aerodynamic chord). The dataare referred to the stability axes, which are a systemof axes having their origin at the center of gravityand in which the Z-axis is in the plane ofsymmetry andperpe
12、ndicular to the relative wind, the X-axis i.sin theplane of symmetry and perpendicular to the Z-axis, andthe Y-axis is perpendicular to the plane of symmetry.The positive directions of the stability axes, of theangular displacements of the airplane and controlsurfaces, and of the hinge moments are s
13、hown in figure 2,CL lift-coefficient (Lif?t/qS)Cx longitudinal-force coefficient (x/qs)C* lateral-force coefficient (Y/qS)c% rolltng-moment coefftci.ent (L/qSb )cm pitching-moment coefficient (M/qSc)C* yawing-moment coefficient (N/qSb).Provided by IHSNot for ResaleNo reproduction or networking permi
14、tted without license from IHS-,-,-HAGA TN ?Oa71 1327 3Chr rudder hinge-mcment cooffictent. 5r2)Tc I effective t.rustcoefficient based on wing areacauseof the turbulence factor of 1.6 for the tunnel, effectiveReynolds numbers (for maximum lift coefficients) wereabout l,0,000 and 1,600,000, respective
15、ly.CorrectionsAll power-on data have been corrected for tareeffects caused by tb.emodel support strut. T p-oyei-off data, however, have not been corrected for t+reeffects because they have been founto be relati”veysmall and erratie on sindlar models, especially withflaps deflected. Jet-boundary corr
16、ections have beenapplied to the angles of attack Iongitud.inal-forcecoefficients, and tail-on pitching-moment coeffi.ci.ents,The corrections were computed as follows:All jetcm=-57”(i-9 c jet-bodary-co. rrectioq factor at wing (0:112total jet=boundary-correction factorat tail(varies between .0.200and
17、 0.210)model wing area (9.4:eaa :J:ure 6illustrates the relation between which iSrepresentative of w constant-power operating curve for aconstant-speed propeller. For simplicity, a straight linevariation of Ttwith CL was used (Tc = 0.161CL).The propeller speed requird to simulate this thrustconditio
18、n was determined from figures 5 and 6. Theapproximate amount of thrust horsepower represented is givenin figure 7 for various model “scales and yi_ngloadings.The value of Tc! for the tests with the propallerwindmilling was about -0.00,.At eaoh ale of attack for power-onmw tests thepropeller speed wa
19、s held constant throuare held constart,the Qlrust coefficient is strictl;rcorrect O:I1;Yat zero :-aw.Latertil”-stahilit#deri.vativPower lo.; ., o.Flapdeflection, . . . . . . . . . . . . .Tail surfaces. . . . . . . . . . . . . . . .Aerodynamic characteristics in yawF2ap neutral . . . . . . . . . . .
20、. . . . .Single slotted flap defb.cted . ; . . . .Double slotted flap deflected . . . . . .aerodynmlc cnaracterislcs in yawsingle slotted flap deflected . .Rudder control characteristics:Flap neutral . . . . . . . . . .Single slotted flap deflected ,Double slotted.flqp deflected . .Effect”owing and
21、fuselage modl.fic.ationson. . .-with the.,.*9*. . . .0. * a71,a71 a11a13a15a15 a15a71 a13a15 a15a15a15a11a13a11a71 a11a15 a15.*I. reduction i.ndihedral effect (reference 5) and thus causedan additional decrease in effective dihedral with power.The reduction in effective dihedral caused by power(mode
22、l with the tail on) ranged from 0 to 3 throughoutthe lift range for the flap-neutral case from 1 to “ to 190 for thefor the single slotted flap, and from 11double slotted fla.Effeot of flap deflection.- The effect of deflectingthe single slotted rlap on efective dihedral is shown infigure 12. Inasmu
23、ch as the double-slottcl-flag”cofifigu-ration was not tested at lift coefficients low enough tomake a direct comparison with the flap-neutral condition,the increments between single- and double-slotted-flapdeflection are also indicated in figure 12 to show the.effect of the double slotted flap.Defle
24、cting the sfngle slotted flap always producednegative effective dihedral. Vlth the ta$l on, thereduction of cZ* caused by flap deflection was slightlyless. The ohange in effective dihedral caused by lgpdeflection was almost independent of the power condition1Provided by IHSNot for ResaleNo reproduct
25、ion or networking permitted without license from IHS-,-,-10 NACA TN 0, 1327used. The analysis in reference 6 indicates that partof the reduction in effective dihedrl when the flapsare deflected can be attributed to the swept-torwardposition ofthe flaps.Deflecting the double slotted flap has an errat
26、icbut pronounced effect on %*” The effective dihedralis reduced with power cm but:is increased with poweroff. This increase with power off is thoughto be aresult of the unsteady flow conditions obtained withthe double slotted flap.Effect f tail surfaces.- The effect of the tailsurfaces on the effect
27、ive dihedral is summarized infigure 13, The data show that the tail suraces almostalways contributed a positive dihedral effect; theincrement was slightly greater with the power on. Itshould be noted that the rolling moment contributedby the vertical tail 1s dependent upon the distncefrom the X-axis
28、 (fig. 2) to the center of pressure ofthe vertical tail. For a given lift coefficient,therefore, it follows that the double-slotted-flapconditicn would show the greatest positive increrm+ntIncL* and the flap-neutral conditiori the leastr Thistrend is shown to occur for theflaa neutral and for thesin
29、gle slotted flsp and.,in the higher lift rage,forthe double slotted flap. Similar resscni.ngcen be followedto explain the vsriation of AC2, wtth lift coeffictent.Further, inasmuch 8S the increment in C2,J resultingfrom the tail is s function of tail Iift,it is cbviousthat, if the rudder deflection f
30、or trim at the variousangles of sislip were considse, dc would besomewh8t reduced. *Effect of modifications.- In an attemt to reducethe large loss in effectivdihedral that occurs-in theflap-down power-on condition, several modifications weremade to the model, tested with the single-slotted-flapconfi
31、guration.One change consisted in removing the flap centersection beneath the fuselage, its span being equivalentto 9.7 percent of the flap span (fig. Thismodification with constant power, however, gave only“slightly less negative effective dihedral whereas, withpower off, it decreased the effective
32、dihedral somewhRt.(See fig. l?(a).) The other modification consisted in.-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN No. 1327placing a spoiler beneath the fuselage as shown infigure l?(b). Again no noticeable improvement JVasevident fort
33、he critical constant-power condition(fig. l7(b).(%)Directional-Stability Derivative CEffect of power.- The effects of .ower on thedirec stability derivative cw are presentedLin figure 11. With the tail on, poer”always increasedthe directional stability for any flap configurationwhereas with the tail
34、 removed, power produced both asmall stabilizing and destablliztng tendency. Thecontribution of power to for the model with tail -c%on varied throughout the lift rae from about O to-2.0011 for the flao-neutral configuration, -0. JOIC to-.003Z with the single slotted flap and -0.0004 to-0.0017 with t
35、he double slotted flap, .-The effect of the windmilling propeller was to causea destabilizing shift of about 0.00020 in c% for mostconditions. With the tail on and wclththe double slottedflaps deflected, the effect was considerably greater(see fig. lC).Effect-of flap deflection.- Deflection of the s
36、ingleslotted flap was found t increase the directionalsta”oility. (See fig. 12:).me dataindicate hat thisincrease is augmented when power is on and furtherincreased when the tail surfaces are In place. Thecontribution of AC1, due to single-slotted-flap.deflection (model with tail on) ranges from -0.
37、0015 to-0.0012 with the windmilling propeller and from -0.0022to -0.0019 for the constant-gower condition. It iSshown i?creference 5 that the increase in -enI isvpartly oaused by the favorable wing-fuselage interferenceon low wtn,g designs, end is further increased by deflectingthe flaps. Deflecting
38、 the double slotted flap also increased.the directional stability for all conditions except thepower-on condition for the model with tail on for whicha considerable destabilizing increment is shown.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-12 N
39、ACA TN NO. 1527Effect of taii surfaces.- The tail surfaces,ks ex,peced,always provide directional.stability “n(See fig. 13.) For the wlndmilling condition, the tailcontributions remained almost constant throughout thelift range for the flap-neutral and single-slotted-flapconfigurations. With constan
40、t power, however, theincrement in Cn was found to increase as CL increased.The increment, moreover, was lways g?eater wlh poweron than with power off.It has been shown (reference 5) that the effect ofwing-fuselage interferece on fin.effectiveness Isfavorable for low-wing designs. An explanation of t
41、hisfavorable Interference is offered in reference 7. Itis sufficient to say that for a low-wtqz,airplane thevertical tail is Ldnly in a rl,on kstbi,lf,zsidewash.The effect of tail configurs.tion on the charac-teristics in yaw are contained in figures 1 to 16.Inasmuch as no ru,dder-freetests were mad
42、e for thesingle-slotted-flap configuration, the rudder-freecharacteristics were estl.matedfrom cross plots oftherudder-hhge-moment and yawing-moment curves. Lessdirectional stability existed in all cases when therudder was free than when held fixed. No rudder lockoccurred for any o.fthe configuratio
43、ns tested althoughsuch a tendency was present. It is interesting ta notethat in the double-slotted-flap configuration wit-htailremoved, the magnitude of ,Cn contributed b the flapis sufficient to cause a stable yawin-moment curva witiflthe ropeller remove”dand, to a lesser degree, with theoropsller
44、windmiling. (See figs. 16(a) and (b).)Directional Control and TrimEffect of power on rudder control and hinge-momentcharacteristics*- A summary of oe ofitie principalcontrol and hinge-moment parameters obtained from tb.eresults of the aw tests.(figs. IS to 2.0)is given intable I.Provided by IHSNot f
45、or ResaleNo reproduction or networking permitted without license from IHS-,-,-FACA T,NNO, 1327 13The progressively reduced rudder effectiveness 6$/d afor thewindmilling condition w-ithsingle-and double-slotted-flap deflection 1s caused”by the increased-directionalstability, which w-aybe atit+buted t
46、o the flaps. Withpower on, the value of b$/c6r was considerably lowerthan with power off for the sinlg-slotted-flap condition.It is apparent in this instance.that the increase indirectional stability caused by power was reater thanthat caused by the increese in q at the tail.For the flap-neutrel con
47、figuration only sliht changesoccurred in the hin,ge-moent parameters d$ anddOhr/h5r with power. The thrust coeficien is low forthis condition (low CL) and therefore power effects vouldalso be expected to be low. For the other fla conditions,the effect of qower is to ir.creasethe values of the hie-mo
48、ment parameters. This effect is especially ,mar%redon values of LChr/?$ for the double-slotted-flap condition.Effect of power on tri7.C- A factor of primeimportance to the pilot is the trim change t:d.tpower.The dashed curve for Cy = on the wi-m-o:nentcurves(figs, 18 to 20) indicates points on the C1l-curveatwhich the lateral force is zero. The point at which thecurve for Cy = O intersects the Cn-axis gives the -rudder deflection and yaw sngle necessary to maintainstraight flight with zero bank, The changes in rudder
