NASA NACA-TN-2504-1951 Effects of wing position and horizontal-tail position on the static stability characteristics of models with unswept and 45 degree sweptback surfaces with so.pdf

1、FOR AERONAUTICSTECHNICAL NOTE 2504EFFECTS OF WING POSITION AND HORIZONTAL-TAIL POSITION ONTHE STATIC STABIIJTY CHARACTERISTICS OF MODEJX WTTHUNSWEPT AND 45 SWEPTBACK SURFACES WITH SOMEREFERENCE TO Iv!ZJTUALINTERFERENCEBy Alex GoodmanLangleyAeronauticalLamgleyField,LaboratoryVa.WashingtonOctober1951,

2、. . . . . . ,- - . . . . .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1 NATIONAL ADVISORY COMMITTEETECHNICAL NOJXTECHLIBRARYKAFB,NMIllllMllllFOR AERONAUTICS OOL55CIL24EFFECTS OF WING POSITION AND HORIZONTAL-TAILPOSITION ONTHE STATIC STABILITY CHA

3、RACTERISTICSOF MODELS WITHUNSWEPT AND 45SWEPITMCK SURFACES WITH SOMEREFERENCE TO MUTUAL INcEBy Alex GoodmanSUMMARYAn investigationwas made to determine the effects of wing”positionand horizontal-tailposition on the low-speed static longl.tudinalandstatic lateral stability characteristicsof airplanem

4、odels having urmweptand 45sweptback surfaces.The results indicatedthat both the unswept and the sweptback low-wing low-horizontal-tailconfigurationswere the optimum configurationsfrom the standpointof longitudinal and lateral stability. The resultsindicated that, for all wing positions,moving the ho

5、rizontal tail”from -the high to the low position resulted in configurationswhich werelongitudinallystable throughot the angle-of-attackrange. For thelateral case, the vertical-tail contributionto the directional stabilitywas increasedby moving the wing from the high to the low-positionbecaueof the f

6、avorable sidewash at the vertical tail arising from the wing-.fuselage interference. The addition of a horizontal tail in the lowposition produced a further increase in directional stability. Theresults also indicated that at low angles of attack the effectivedihedral due to wing-fuselage Interferen

7、ceincreased as the wing heightwas increased - that is, from approximately -4 for the low-ting configu-ration to 5 for the high-wing configurationThis effect could bepredicted with fair accuracyby available theory. .r,At low angles of attack, the lateral force on the fuselage wasincreasedbecause of t

8、he end-plate effect when a wing was.placed in thehigh or the low position. However, the lateral force on the fuselagedecreased for the low-wing configuration-andincreased for the high-wingconfigurationas the angle of attack was increasedbecause of the variationin the distribution of sidewash on the:

9、fuselage.with )unswept wing alone and for all configurationswithCORRECTIONSdetermine the effectsand data for theswept surfaces.Approximate corrections,based on unswept-wing theory, for theeffects of jet boundaries (reference7) have beep applied to the angleof attack and longitudinal-forcecoefficient

10、. The data have alSO beencorrected for the effects of blocldng by the method given in reference 8. . - - .-.-. - _. .:Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 NACA TN 2504Corrections for the effects of suppxt-strut interferencehave beenappli

11、ed to Cx and . Thetares determined for the swept configu-rations were also applied to the unswept configurationssince the taresdeterminedfor the unswept and swept wings were similar. The effectof support-strutinterferenceon CL was found to be negligible forthese tests and, therefore,the tare correct

12、ionswere not applied.METHODS OF ANALYSISThe results of the present investigationare analyzed in terms ofthe individual contributionsof the various parts of the models to theaerodynamiceffects.characteristicsand to the more tiportantinterference.Longitudinal-StabilityCaseIn accordancewith conventiona

13、lprocedures (for example, as outlinedin reference 1), the pitching-momentplane canbe expressed ascm= %J % + %;oefficient”forthe theFor this investigation,/ c. _Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-2,.I?ACATN 2504 9however, the wing and hor

14、izontal tail were geometrically similar;therefore, can beteristics asexpressed in terms of the isolated wing charac-?-c%( )-kcosa+ sina(5)The interference incremeritsCm and Cm canbe used toevaluate the rate of change of downwash at the horizontal tail withangle of attack however, the trends shown by

15、 these incrementsare believed to be reliable.The present results should be alicable to full-scaleresults onlyfor the angle-of-attackrange before flow separation occurs. h increase.-.-.-. - -.- . -.- -. -Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,

16、-12in Reynolds mxiber would be exyected to extend the linear range of thedata to higher angles of attack.RESULTS AND DISCUSSIONPresentation of ResultsoThe static longitudinal stabili characteristicsof the variousconfigurationsinvestigated are given in figures 4 to 13 and the staticlateral stability

17、characteristicsme presented in figures 14 to 29. Asummary of the configurationsinvestigated and of the figures that presentthe basic data for these configurationsis given in table IV.Static Longitudinal Stability CharacteristicsWing characteristics.-The lift, longitudinal-force,and pitching-moment d

18、ata for the unswept and 450 sweptbackwings of the presentinvestigationare presented in figure 4. The values of the experimentallift-curve slopes, taken through zero angle of attack, of 0.0620 and0.0545 are in fairly close agreement tiththe theoretical values of 0.064 -and 0.0530 given for the unswep

19、t wing and the 45 sweptbackwing,respectively, in reference 9. At low angles of attack the aerod-ccenters of the wings me located at about 24.9 percent (A = Oo) and25.2 percent (A = 45) of the mean aerodynamic chord. The theoreticalvalues given in reference 9 for the unswept and 45 sweptbackwings are

20、25 percent a-26 percent, respectively. The variation of Cm with aobtainedwith the unswept and 45 sweptbackwings is linear for the angle-of-attackrange before flow separation occurs (approximatelyup toa= 8 as indicated in fig. 4). At the angle of attack at which flowseparationoccurs, an abrupt change

21、 in the variations for bothWiIl is obtained. In the case of the unswept wing, becmeshighly negative (stabilizing);whereas, for the 45 sweptbackwing, c%becomes positive (destabilizing)Many of the aerodynamicparameters of a complete airplane therefore,some considerationmust be given to the angle-of-at

22、tackrange over whichthe flow does not sepsrate from the wing. As pointed out in reference 10,an indication of the limit of this range can be obtainedby locating theCL2initial break in the drag index curve - % against angle of attack.A plotof thisincrementforthe 45Bweptbackwingcanbe obtainedfrcunProv

23、ided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-r,.NACA TN 2X4figure 15 of reference 6.about . A similarbreaksame angle for the unswept13The figure shows a break in the curve atin the drag index curve occurs at about thewing. Correspondingbreaks in the c

24、urves ofthe aerodynamic characteristicsof combinationsincluding the wings areto be expe$ted at about this ssme angle of attack. For example, thebreaks in the Cw variation with a obtained for the wing alone occursat about a = and for the C% variation obtained for the wingsalone, at about a = 8. An in

25、crease in Reynolds number wouldbeexpected to extend t% angle-of-attackrange before flow separationoccurs.Fuselage and fuselage-tail characteristics.-One of the main effectsof the isolated fuselage on the static longitudinal stability is thecontributionof an unsble pitching mmen as shown in flgtailsi

26、tions as affected by the fuselage are presentedin figure 10 and were obtainedby the procedure explained in the sectionentitled “Methods of Analysis.n The value of A3 at zero angle ofattack obtained for the high horizontal tail probably results, as statedpreviously, from the fact that the streamlines

27、of the flow tend to followthe fuselage contour. The reason that the value of A3Cm for the sweptlow-horizontal-tailconfigurationis not zero at a = Oo has beendiscussed in the section entitled “Limitationsof Results.” At highangles of attack, the values of Cm decrease for both unswept and. . . .-. - .

28、 _ _-. . . .- .Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-14swept configurationsand in some cases becaneinterference). Also at high angles of attackNACA TN 2%4.negative (favorablethe unstable moment ofthe fuselage has increased. These effects, i

29、n addition to the decreasein at high angles of attack (equation (5),result in a decreasein the values of for both the unswept and swept fuselag-tailcombinationsat high angles of attack. The decrease in at highangles of attack is greater for the high-horizontal-tailthan for thelow-horizontal-tailconf

30、igurationssince the interference increment A3ti less stabilizing (comparefigs. 5 and 10).Wing-fuselage characteristics.-The adtition of a 45 swept wingin the mid, high, or low positions (Wl,W2, orW3, respectively) to thefuselage produced Characteristicsdmilsr to that obtained for thewing alone (see

31、figs. 4 and 6). For the unswept wing configurations,the contributionof the fuselage at low angles of attack to the pitching-moment characteristicshas a destabilizing effect. A mall amount ofwing-fuselage interference()AICm which can probably be attributedtothe resrward location of the wing-fuselage

32、juncture is thereby indicated.A similar result (an increase of the unstable pitching-moment contributionof the wing-fuselage combinationwith a rearward shift of the wing-fuselage juncture)was obtained in reference 4 for an unswept midwingconfiguration. For the sweptbackwing configurationsat low angl

33、es ofattack, the wing-fuselage interference cancels the usual unstablepitching-moment contributionof the fuselage. Apparently this effectis due to the fact that there is a loss in lift over the wing centersectionbecause of the fuselage interference. In the case of the swept-back wing, this loss occu

34、rs over sections of the wing which sre forwardof the aerodynamic center and results in a stabilizingmoment. At highangles of attack, the contributionof the to th pitcng-momentCharacteristicsof the wing-fuselage combinationspredominates (favorableinterference) and results in pitching moment trends wh

35、ich are similarto those of the wing alone (compsrefigs. 4 and 6).sThe wing-fuselage interferenceincrement AICm evaluated from thebasic databy the procedures elained in the section entitled Methodso? Analysis” is presented in figure 11. The fact that Al% for themidwing configurationsis not zero at a

36、. 0 is probably due to aslight asymme of the wings. (See the section entitled “Limitationsof Results.”) The trends of shown in figure 11 are in agreementwith the results presented in figure 6.The lift-curve slope of the wing-fuselage configurationsat a = 0was found to be slightly higher than that of

37、 the wing alone(seefigs.4Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACA TN 2w4 “ 15and 6). A shnilar result was obtained in reference 4 for a m.idwingconfiguration.A comparison of C that is, the combination of thevertical and horizontal tails p

38、roduced smaller increments in the parametersthan the vertical tails slone (see fig. 15). The effective aspectratios of the unswept and swept tails as determinedby the procedure ofreference 6 are presented in figure 21 in the form of the ratioC%)H on-Hplotted against the horizontal-tsil-heightratio %

39、/%for . 0 and sre comparedwith the results of reference 3. Theresults of figure 21 illustrate the effects on the derivatives %and CnY just discussed. A shila result was obtained in reference 5.The positive increase in CZ at = 0 (fig. 15) is provided*by the vertical tail. As the angle of attack is in

40、creased, the verticaldistance between the horizontal tail center of pressure and the roll axisdecreases; thereby a decrease of %$ with angle of attack results. Theaddition of the horizontal tail in the low position (HI) resulted in a- . . . -. .- - . - ,. - . -Provided by IHSNot for ResaleNo reprodu

41、ction or networking permitted without license from IHS-,-,-18 NACA TN 2Y4smaller increase in C at”=oo. With the tail in the high position(), the value of c2+ at=OO was about the same as that obtainedwith the fuselage - vertical-tail configuration. These effects sreprobably due to the antisymmetrical

42、load induced on the horizontal tailby the verticsl tail. This antisynunetricalloading can be accountedfor qualitatively (as was done in references 5 and 12) by consideringthe effects of the tip vortices of the vertical tail acting on thehorizontaltail when the horizontal tail is at .o” and the entir

43、etail assembly is at an angle of yaw. With the horizontal tail in thelow position (Hl),the tip vortex at the base of the vertical tail wouldbe expected to have a predominant effect and would tend to produce anegative increment in Cz .$ For the high tail () the loads inducedby the vertical tail on th

44、e horizontal tail tend to cancel.Wing-fuselage chsracteristics.-In order to analyze the effect ofwing position on the latersl stabili characteristics,a qualitativeanalysis similsr to the analysispresented in reference 12 will be madeof the flow about a yawed hi that is, the flow about thefuselage in

45、duces an upwash velocity on the advancingwing panel and athe lateral force on the fuselagedecreased for the low-wing configurationand increased for the high-wingconfigurationas the angle of attack was increasedbecause of the variationin the distributionof sidewash on the fuselage with angle of attac

46、k.Langley Aeronautical LaboratoryNational Advisory Committee for AeronauticsLangley Fieldj Vs., July 11, 1951.- - - _ _ . . . - - Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-24 NACA TN 2%41.2.3.4.5*6.7*8.9*13EFEmNcEs,House, Rufus O., and Wallace,

47、 Arthur R.: Wind-Tunnel Investigationof Effect of Interferenceon Lateral-StabilityCharacteristicsofFour NACA 2301!2Wings, an Elliptical and a Circular Fuselage, andVertical Fins. NACA Rep. 705, 1941.Recant, Isidore G., and Wallace, Arthur R.: Wind-Tunnel Investigationof the Effect ofVerticalPosition

48、 of thq Wing on the Side Flow inthe Region of the Vertical Tail. NACA 804, 1941.Murray, Harry E.: Wind-Tunnel Investigationof End-Plate Effects ofHorizontal Tails on a Verticsl Tail Compared with Available Theory.I?ACATN 1050, 1946.Jacobs, Eashnan N., and Ward, Kenneth E.: Interference of Wing andFuselage from Tests of 209 Combinations in the”N.A.C.A.Vsriable-Density Tunnel. NACA Rep. 540, 1935.Brewer,