NASA NACA-TN-825-1941 Wind-tunnel investigation of effect of yaw on lateral-stability characteristics III - symmetrically tapered wing at various positions on circular fuselage wit.pdf

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1、NAT IOI?AL ADVISORY COMMITl%E FOR A?H?CETAUTII.-NOC 825a71_i .:,.-. . =iiIIKD-TUNNEL INVEST ZGAZ!IOE OEEEFECT OF Y of the three longitudinal locations tested, themaximum effective dihedral:was obtained at the centralposition. The effect of the wing-fuselage interferenceon directional stability inore

2、ased favorably when the-.-.-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2 NACA Technical I?ote No. 825wing location was moved forward. The influence of wlng-fuselage interference ”on”the directional stability con-tributed by the vertical tail wa

3、s beneficial for the low-wing combination a“nd detrimental for the high-wing com-bination and this influence increased as the wing posi-tion was moved rearward. The fillet prevented suddenchanges iq the lateral-stability characteristics of thelow-wing model at high ,angles of attack below the stallb

4、y delaylng the occurrence of the Imrble at the wing-fuselage Juncture.INTRODUCTIONThe rates of ohange of rolling-moment, yawing-moment,and lateral-force coefficients with yaw are importantfactors in the calculation of the-lateral stability of anairpla.neand, consequently, these parameters .have been

5、 thesubject of extensive investigation by the ,NACA. The ef-fects of stich variables as tip shape, dihedral, taper, andsweep are reported in references 1 and 2. A theoreticaldetermination of lateral-stability characteristics ofwings as affected by some of these factors is preeentedin reference 3. Th

6、e effect of wing-fuselage interferenceon lateral-stability characterist-ics has been investigatedfor wings of various tapers and sweeps in such combinationswith circular and elliptical fuselages as to form high-wing, mtdwing, and low-wing monoplanes. These hesults aregiven id references 4 and 5.The

7、tests reported herein are a continuation of theinvestigation of wing-fuselage interference and were madewith the circular fuselage and symmetrically tapered wingused in the tests described in reference 4. The chiefvariable was the longitudinal position of the wing on thefuselage. The wing was locate

8、d one-half of the mean chordlengthforward and rearward of the position used for thetests of reference 4. At each horizontal location themodel “was tested as a high-wing, a midwing, and a low-wingmonoplane. Data for the central posftion, taken from ”ref-erence 4, are included for comparison.APPARATUS

9、 AND MODELSa71a14BThe tests were made in the NACA 7-=by 10-foot windtunnel with the regular six-component balance. The tunneland the balance are described tn references 6 and 7.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA Technical Note No. 8

10、25 3i“8The model (see fig. 1) was the same as the one usedfor the tests of reference 4, except that the fuselagewas recut so that the wing cou3d be mounted about 0.5 ofthe mean chord forward and about 0.5 of the mean chordrearward of the original position. For the high-wing andthe low-wing combinati

11、ons the outer surface of the wing*#as made tangent to the surface cif the fuselage. In allcases the wing was set at 0 incidence.The 3:1 Symmetrtc.ally tapered wing, which is fullydescribed inreference 3, is of ?JACA 23012 section withthe maximum upper surface ordinates in one plane, givingthe chord

12、plane a dihedral of 1.45. The tips are fornedof quadrants of approximately similar ellipses. Thesweepback of the locus of one-quarter chord points is4.750, the area is 4.1 square feet, and the aspect ratiois.6.l.The, fuselage is circular in cross section and wasmade to the ordinates given in referen

13、ce 8. The verticaltail is of NACA 0009 section and has an arbitrary area of53.7 inches, which includes a portion through the fusela”geas shown in figure 1. Its aspect ratio, based on thisarea and the span measured from the center lne of thefuselage, is 2.2.Split flaps df :20-percent chord arid 60-pe

14、r.cent spanwere made of l/16-inch steel. For the high-wing and themidwing combinations, the flaps ”were cut to allow for thefuselage, and the gaps between the fuselage and the flapswere sealed. The flaps were attached at a 600 setting.ihen the wing WaS in the low rearward positiq, afillet was used.

15、The fillet is shown in f“igures 2(a) and2(b).TESTSThe test procedure was similar to that used in previ-ous investigations (reererices 4 and” 5). The wing wastested in the high, the middle, and the low positions at0.5 of the mean chord both forward and rearward of thelongitudinal locations used,in re

16、ference 4. Tests weremade with and without the flaps and with and without thevertical tail for all wing positions.All combinatioris tiere tested at angles of attackProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 NACA Technical Note No. 825SO, 0, -d

17、 5:;from -10 to 200 with the model yawed - Ayaw range of -10 to 15 waB investigated at anglesattack 1 and 4 below the angle of attack for maximumlift.A dynamio pressure of 16.37 pounds per square foot,which corresponds to a velocity of 80 miles per hourunder Standard conditions, was used in all test

18、s. TheReynolds number baeed on a mean wing chord of 9.842 incheswas about 609,000. Based on a turbulence factor of 1.6,the effective Reynolds number was about 975,000.RESULTSThe data are given in standard nondimensional coef-ficient form with respect to the wind axes and the center-of-gravity locati

19、ons shown in figure 1. The coefficientsfor the fuselage alone and fuselage plus fin are basedon wing dimensions.CL lift coefficient (L/qS)CD drag coefficient (D/qS)c,m pitching-moment coefficient (M/qS=)Cyf lateral-force coefficient (Y/qS)y+ slope of curve of lateral-force coefficientagainst yaw (ae

20、y/avOcf rolling-moment coefficient (Lt/qSb)CL slope of curve of rollin -moment coefficientagainst yaw (acljaiff fen 1 yawing-moment coefficient (N/qSb)c1Q slope of curve of yawing-moment coefficientagainst yaw (M1n/aV1)Ax change in partial derivatives caused by wfng-fuselage interference*#Liz change

21、 In vertical tail effectiveness caused bywing-fuselage interferenceProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IJACA Technical Note No. 825where., .LDliftdraglateral forcerolling momentpitching momentyawing momentdynamic pressure (1/2pVa) .tunnel

22、 air velocityair densitywing area,“wing span.:average wing chord .“.angle of attack corrected to free stream, degreeswind-tunnel angle of attack, degreesangle of yaw, degrees .,angle. of flap deflection, degrees. . . .Lift. drag, and pitching-moment coefficients for thevarious wing-fuselage arrangem

23、ents are presentetl in fig-ure 3. l?hevalues of a and CD shown in this figurewere correc%eri to free air, but in all subsequent figuresno corrections to a; were made. P1o*s of gelling-moment,yawing-moment, and Iateral-for.ce coefficients for theloy-wih tom%inattoq wire given in figures 4 to 6 for ya

24、w-tests at ”l”and 4: below the angle of attack for maximumlift. he.lateral-stabilfty characteristics of-componentparts ,of the model appear in figure 7.:.”-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-6 NACA Technical Note No. 825The increments of

25、 the partial derivatives with r$-spect to $ of rolling-moment, yawing-moment, and lateral- rforce coefficient due to wing-fuselage interfezenoe 1and due to wing-fuselage interference on the vertical tailA are shown in figures 8 to 13 and in figures 14 and 15by contours for at = OO. The zero value of

26、 angle cf at-tack , for which the contours were made, is considered rep-resentative because the interference increments do notvary greatly with angle of attack. All data for the cen-tral longitudinal wing positions were taken from reference4. The increment Al is the difference between the slopefor t

27、he wing-fuselage combination without the fin and thesum of the slopes for the wing and the fuselage, eachtested separately. Thus, A= is the change in cCtn *J and Cyw oaused by wing-fuselage interference forthe model without the tail. The increment A2 is thedifference between the slope produced by th

28、e vertical tailwith the wing present and the slcpe produced by the verti-cal tail with the wing absent. The increment Aa istherefore the change in effectiveness of the vertical tailcaused by the addition of the wing to the fuselage. If,for example, the value of CnlVa71for the complete model Isdesire

29、d, the following equation may be used: *cnI wCntw (Will)+Cnlw (fuselage and tail) +AZCnlW+AaCntVValues of Ca:w and CY* for the complete model may beobtained in a similar manner. .The values of cl Cnt$, and (jYt$ “used to com-pute 41 and Aa were obtained from tests at -5 and 5yaw by assuming a straig

30、ht-line variation between thosepoints. This assumption has been shown in reference 5 *Obe valid except at high. angles of attack. Tailed pointson the curves of figures 8 to 13 were obtained from slopesmeasured from curves in figures “4 to 6 and others similarto these.The values of cl Iv .and C tnlJl

31、 depend!,on the center- 1of-gravity location. All data, except aB noted, are the forward-wing arrangements areexpected to be more stable in pitch than the rearward-wingarrangements. .The effeo of the fillet On the characteristics ofthe low-rearward arrangement (figs. 3(f) and 3(g) is Ofinterest. The

32、 fillet prevents separation below the normal stall and thus increases the maximum lift coefficient andsmooths the h hence the discussion in this report will be confinedchiefly to the effects of changing th wing position lon-gitudinally along the :uselage. The effect of verticalposition of the wing i

33、s, ho!ever, about the same regard-less of longitudinal location.The increment AIC!$(shown.in figs. 8 and 14) !spositive for the high-win combinations and negative forthe low-wing combinations. Variations with longitudinalchanges in wing location are swa12. If the low wing withflaps neutral is moved

34、either forward or rearward, thereis a small increase in effective dihedral. The increase,however, is not enough to make %cq positive. Forall wing positions with the decrease i“sgreater for movement forward. The fiilt on the 10w-rearward combination with 6$= Oo (fig. 8(c) removesthe break and the rev

35、ersal o sign caused by the burbleat 10o angle of attack.nfw (figs.The parameter, A C 9 and 14) has a ten-dency to become more stabilizing as the wi moves forward,although the trend is not consistent, especially in thecae of the low-wing combination. Ylie contours (fig. 14)show an.increase in the sta

36、bilizing influence of ACIE$as the wing is moved forward, QErticularly when 6f = 60,but the tendency does not hold for the entire unstalledangle-of-attack range. As in the case of AICI( , thefillet prevents. the, sudden divergence of AzCntti at highangles ofttack caused by flow separation QZ he wingr

37、oot.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA Technical 170te No. 825 9.,When AGnrW is recalculated for center-of-gravity,.location fixed at the central position on the fuselage,the foregoing effects are not apparent or are even re-versed

38、in some cases (figs. 9(d) and 9(e).The value of %GY is usually positive hut is.small for midwing combinations (figs. 10 and 14). Withflaps neutral, movement of the wing either forward orrearward has very little effect, but th-e t“bridenc-yis to-ward a decrease in ALCyt . ifIthflaps deflectedw (500,m

39、ovement of the wing in any direction from the midcenterposition increases the lateral force due to interferencefor angles of attack of normal flight. when the wing isin the high or the low position, it proba%ly acts as apartial end plate, Increasing the effective aspect ratioof the fuselage that is

40、acting as an airfoil when yawed;hence, an increase in lateral force is to be expected.Effect f Wing-fus 1 e interference n verticaltai.- The i;crement b;c;f$ is shown in igures 11 and15, where the effect of longitudinal position of the wingis seen to be small and erratic.In general, (figs. 12 and 15

41、) is Po_S.it$.ye2A2Cn t.,or destabilizing, for the high-wing combinations and isnegt”iire, %r stabilizing? for the low-wing combinations.he longitudinal position of the wing has little effect.In mo-st cases, the increment AzCn becomes more stabi-lizing as the wing is moved rearward along the fuselag

42、e.With flaps neutral, the ffllet decreases the directionalstability at low and mediun angles of attack but producesno change at high angles below the stall. With flapsdeflected 600, the fillets increase the directiorial sta-bility and the variation is lese eratic at high angles ofattackoWhen moments

43、 based on a fixed tail length are con-sidered, there is a small but definite tendency towardan increase in interference as the wing is moved rearward.This interference is destabf,lizing- for the caeq of thehigh wing and is stabilizingfor the case of the low wing(figs. 12(d) and 12(e). J ,“. : -“,. .

44、 -In general, A2CY ti (figs; 13 and 15) ie positivefor the low-wing combinations and negative for the high-.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-10 NAGA Te”ch.nica”lNote No. 8“25wing combinations. The effect is small; but the trend istowar

45、d more .flntererence as the wing is moved rearwa.rdwhich decreases the lateral force of the high-rearwardcombination andincreases thje lateral force of the low-rearward coinbitiation(figs. 13(a) and 13(c). l!he con-tours (fig. 15), however, show that this effect may bechiefly caused by the fact that

46、 the forward wings arecloser to the centqr line of. the fuselage. With flapsdeflected 60, the fillet increases the lateral force onthe vertical tail. At high angles of at.tack there isalso an increase with the flaps neutral.Some of the reltions between Ac!an. and A2cyare of interest. The existence o

47、f sidewash angles in theregion of the vertical tail for a modei very sinilar tothe present one was reported in reference 9. For the low-.wing combination the sidewash angles increased the direc-tional stability, while for the high-wing combinations thesidewash angles decreased the directional stabil

48、ity.Since the present report shows that.the rearward- wings havean even greater influence” on the ,veztical tail, “there mustbe an increase in the sidewash angles. A comparison ofAzCnt and A2Cy , with and wit”hotitthe fillet for thelow-rearward combiation shows that-,“in general, the fil-let causes a forward shift in the lateral center of pres-“sure.CONCLUSIOiTSThe effect of changing the.wing position longitudinal-ly cYnthe fuselage was small when compared with the effectof changing the wing position vertically. For the low-wing combinations with flap neutral, there