1、NATIONALADVISORY COMMITTEEFOR AERONAUTICSINVESTIGATIONTECHNICAL NOTE 3135MUTUAL INTERFERENCE EFFECTS OFVERTICAL-TAIL-FUSE LAGE CONFIGURATIONS INBy William II. Michael, Jr.Langley Aeronautical LaboratoryLangley Field, Va.SIDESLIPWashingtonJanuary 1954AFM2C.Provided by IHSNot for ResaleNo reproduction
2、 or networking permitted without license from IHS-,-,-TECH LIBRARY KAFB, NhlNATIONALADVISORYCOMMITTEEFORAERONAUTICS Illllmlllllllllll!lulllllU13b59?4TEcHmcALml!lz 3135INVESTIGATION OF MUTUAL INTEFU?ERENCEEFFECTS OF SEVERALVEIU21CAL-TAIL-FUSELAGECONFIGURATIONS IN SIDESHPBy William E. Michael, Jr.SUMM
3、ARYTests were made on three circular-src-fuselage and nine unswept-vertical-tail nmdels in order to investigate interference effects betweenfuselages and vertical tails in sideslip. The mutual interferenceeffects, and thus the effectiveness of the vertical tail in producingdirectional stability, app
4、ear to be mainly dependent upon the ratio ofthe vertical-tail span to the fuselage diameter at the position of thevertical tail and upon the vertical-tail aspect ratio and to be relatively. independent of the fuselage fineness ratio. The increase in vertical-tail effectiveness is largest for small v
5、alues of the ratio of thevertical-tail span to the fuselage diameter and decreases as this ratio.increases; in general, the effectiveness increases with increase in thevertical-tail aspect ratio. The magnitude of the induced loading on the .fuselage is comparable to the magnitude of the correspondin
6、g inducedloading on the vertical tail. The interference effects of the verticaltail and the fuselage on one another may result in a tail effectivenessof the tail-fuselage combination which is different from that of thetail alone, the difference being an increase of O to 100 percent of thetail-alone
7、effectiveness for the configurations tested. The verticalcenter-of-pressure calculations indicate that, as the span-to-diameterratio decreases, the fuselage loading becomes proportionally more impor-tant and the center of pressure moves downward toward the tail root orthe fuselage center line. The l
8、ongitudinal center of pressure is in thevfcinity of the tail quarter-chord line.Some theoretical calculations of the interference effect of a cyMn-drical body on adjacent lifting surfaces gave good agreement with thecorresponding measured values for the vertical-tail plan forms considered.INTRODUCTI
9、ONAnalyses of present-day airplanes have indicated that interference.effects between component parts of airplanes have a significant influenceon aircraft loads and stability derivatives. This influence is found to4Provided by IHSNot for ResaleNo reproduction or networking permitted without license f
10、rom IHS-,-,-2 NACA TN 3135be important in the case of mutual interferencebetween the fuselage and -the vertical tail. A number of experimental investigationshave beenmade to determine the effects of various fuselage, vertical-tail, and +horizontal-tail combinations on complete-model characteristics
11、(for .instance, refs. 1 to 4). Little information is available, however, whichgives an indication of the relative loading on the component parts or ofthe mutual interferencebetween the parts, as affected by fuselage andvertical-tail geometric characteristics.The purpose of the present investigation
12、is to determine the mutualinterference effects between the fuselage and the vertical tail by meas-uring the forces and moments on the model components separately and incombination and then finding the differences. The models used in theinvestigation consisted of fuselage and vetiical-tail components
13、 only.Some theoretical calculations also were made to determine the interferenceeffect of a cylindrical body on adjacent lifting surfaces and the resultsare compared with the experimental data.SYMEd3LSAND COEFFICIENTS.Positive directions of forces, moments, md angles are shown infigure 1. The symbol
14、s and coefficients used herein are defined as #follows:a angle of attack, degA aspect ratio P angle of sideslip, degbt tail span, ft% assumed wing span, ftc chord, ftD fuselage diameter, dismeter of fuselage at position ofvertical-tail quarter-chord line, ftlt tail length, horizontal distance from c
15、enter of gravity ofmodel to tail quarter-chord line, ftbt Cnpeffective tail-length parameter, bw CYP dynamic pressure, lb/sq ftProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NACATN3135 3*%zCnvertical-tail area, sq ftassumed wing sxea, sq ftvertical
16、distance, measured from intersection of vertical-tailquarter-chord line and fuselage surface, f%rolling moment, ft-lbyawing nmment, ft-lblateral force, lbLrolling-moment coefficient, qstbtyawtig-moment coefficient, *qbta71Cy lateral-force coefficient, qstSubscripts:t isolated vertical-tail contribut
17、ionAl contribution due to interference effect of fuselage onvertical tail42 contribution due to fiterference effect of vertical tail onfuselageAPPARATUS AND TESTs.The mdels used in this investigation consisted of three mahoganycircular-arc fuselages and nine mahogany vertical tails. Sketches of.Prov
18、ided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 NACA TN 3135wthe vertical tails and fuselages are given in figure 2 and geometriccharacteristics of the tails are given in table I. The vertical tailshad zero sweep of the quarter-chord line, a taper rati
19、o of 0.6j and a71NACA 6AO08 profiles in sections perpendilar to the quarter-chord line.The three fuselages had circular cross sections and fineness ratios of10.o, 6.67, d .o. The msximum thickness was the same for all threefuselages. The fuselages and vertical tails sre designated as indicatedin fig
20、ure 2.The vertical tails were attached to the fuselages through a strain-gage arrangement which allowed the lateral force.and root bending momentof the tail to be measured independently of the measurements on thecomplete mdel (i.e., fuselage plus vertical tail). Figure 3 is a photo-graph of a vertic
21、al tail attached to a strain gage. Figure 4 is a photo-graph of a complete configuration mounted on the support strut. Eachfuselage had one mounting position for the vertical tails such that thetrailing edges of the tails with the largest chords extended to thetrailing edge of the fuselage. Fuselage
22、 F3 had only one mountingposition, but fuselages F1 and F2 each had two mounting positions,one as described and smother at a more fomard position at which thefuselage diameter was the same es the fuselage diameter at the mountingposition on fuselage F3 (see fig. 2(b).Sideslip tests to determine the
23、lateral force on the isolated verti-cal tails were made with an arrangement which was designed to give whatwas considered to be a minimum of interference from the supportingmembers. The strain gage was mounted on a metal bar which extendedwellforward of the support strut, and the vertical tails were
24、 connected tothe gages by another bar attached to approximately the midspan of thevertical tall. The arrangement is shown in the photograph presented asfigure 5.Tests were made through a sideslip-angle range of flOO for thefuselages alone and for each vertical tail at all the fuselage positions,and
25、balance-system measurementswere made of the lateral force, rollingmoment, and yawing moment. Although this investigation did not undertakea thorough study of the effects of angle of attack, results for botha= 0 and a= 10 are presented to give some indication of the effectsof angle of attack.A1l.test
26、s were made in the 6-foot-diameter rolling-flow test sectionof the Langley stability tunnel. The tests were made at a dynamic pres-sure of pounds per square foot, corresponding to a Reynolds numberrange of 3.90 x 105 to 7.78 x 105 based on the average tail chord. w.Provided by IHSNot for ResaleNo re
27、production or networking permitted without license from IHS-,-,-NACA TN 3135 5Jet-boundary correctionswere not applied to the data because thecorrections were found to be negligible. Also, no correctionswereapplied for effects of tunnel blockage or suprt-strut interference.PRESENTATION OF RESHll%The
28、 stability-derivativedata obtained in this investigation, con-sisting of results obtained from the strain-gage measurements and thebalance-system measurements, are presented in tables II and IIT. Thederivatives were obtained from the slopes of faired curves drawn throughthe experimental-dataplots of
29、 the forces and moments against the angleof sideslip. The slopes were taken at = Oo and were in most caseslinear through a rsnge of sideslip angle of approxtitely t80. wtable II snd in the discussion, the derivatives are based on the individualtail dimensions for convenience in making comparisons. F
30、or the balance-system results presented in table 111, the derivatives were based on aconstant assumed wing area of 2.25 square feet and a span of 3.0 feet inorder to give an indication of the relative magnitude of the resultsobttined. The mcment results from the strain-gage tests are not presentedin
31、 table .11but are used in the discussion to determine the verticallocation of the centers of pressure.DISCUSSION OF RESULTSEffectiveness of Isolated Vertical TailsThe results of the measurements of ()cYp t sre presented in fig-ure 6 as a function of the vertical-tail aspe “-the curves show that the
32、magnitude “of ( whereas for tails with smaller values ofT?.the loading is centeredsmallest values of fuselage itself. Thus,nearer the fuselage. For the tails with thethe loading is centered on the top half of the .for the tails with large values of %, the fuse-JJlage loading () is a small percentage
33、 of the combined loading;c%whereas for the tails with small values of the loading on the fuse-lage becomes an important part of the combined loading (see fig. 11), aconditionwhich causes the center of pressure to be near the tail root .Jor perhaps even below the tail root. -.vComparison With Some Th
34、eoretical Calculations +In view of the fact that the fuselage”interferenceon the verticaltail appears to be only slightly dependent upon the fuselage fineness “-ratio, some calculations were made to determine the interference effectsof infinitely long circular cylinders on adjacent lifting surfaces.
35、 Themethod used in the calculations is similar to that used in reference 6for calculatingwing-fuselage interference.effects, except that in thepresentcalculations no corrections are made for finite body length orfor rigorously satisfyingthe fuselage boundary conditions. In the pres-ent calculations,
36、 the vefiical tails are represented by a horseshoe vortexsystem with images situated inside the cylinder at the proper positions.The velocities induced at the three-quarter-chordpoints of the vertical : =tail by the vortex system and the image vortex system are set equal tothe velocity distribution
37、on the vertical tail due to sideslip angle andthe influence of the fuselage. Solution of the set of simultaneousequations gives the vortex strengths and t_husthe forces on the verticaltails.The results of the calculations are presented in figure 15 alongwith the corresponding experimental resul-bg f
38、rom figure 9. In general,these calculations appesr to provide a good estimation of the”increase in effectiveness of the vertical tail due to the presence of the fuseiagefor the configurations considered. a71.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IH
39、S-,-,-NACATN 3135 U.CONCLUSIONSTests made in sideslip on three circular-arc-fuselageand ninevertical-tail models to-determine mutual interference effects betweenfuselages and vertical tails have resulted in the following conclusions:1. The mutual interference effects, and thus the vertical-taileffec
40、tiveness in producing directional stability, appear to be mainlydependent upon the ratio of the vertical-tail span to the fuselage diam-eter at the position of the vertical tail snd on the vertical-tail aspectratio and to be relatively independent of fuselage fineness ratio.2. The increase in vertic
41、al-tail effectiveness due to interferenceis largest for small values of the ratio of the vertical-tail span tothe fuselage diameter and decreases as this ratio increases. The.inter-ference effect in general increases with increase in vertical-tail aspectratio.3. The magnitude of the induced loading
42、on the fuselage is comparable.to that of the corresponding induced loading on the vertical tail.4. The interference effects of the vertical tail and the fuselage.on one another may result in a tail effectiveness of the tail-fuselagecombination which is different from that of the tail alone, the diff
43、er-ence being sn increase of O to 100 percent of the tail-alone effective-ness for the configuratims tested.5. The vertical center-of-pressure calculations indicate that as theratio of the spsn to the dismeter decreases, the fuselage loading becomesproportionally more important and the center of pre
44、ssure moves downwsxdtowsrd the tail root or the fuselage center line. The longitudinalcenter of pressure is located in the vicinity of the tail quarter-chordline.6. Some theoretical calculations of the interference effect of acylindrical body on adjacent lifting surfaces gave good agreement withthe
45、corresponding measured values for the vertical-tail plan formsconsidered.Langley Aeronautical Laboratory,National Advisory Committee for Aeronautics,Lsngley Field, Vs., November 2, 1953.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-12 NACA TN 3135R
46、EFERENCES1.1. Pass, H. R.: Analysis of Wind-Tunnel Data on Directional Stabilityand Control. NACA TN 775, 1940.2. Queijo, M. J., and Wolhart, Walter D.: Experimental Investigationof the Effect of Vertical-Tail Size and Length and of FuselageShape and Lenh on the Static Lateral Stability Characterist
47、icsof a Model With 45 Sweptback Wing and Tail Surfaces. NAC!ARep. 1049,1951.(SupersedesNACATN 2168.)3.Letko,William: Effect of Vertical-Tail Are,aand Length on theYawing Stability Characteristics ofs Model Having a 45 SweptbackWing. NACATN 2358, 1951.4. Brewer, Jack D., and Liechtenstein,Jacob H.: E
48、ffect of HorizontalTail on Low-Speed Static Lateral Stability Characteristics of aModel Having 45 Sweptback Wing and Tail Surfaces. NACA TN 2010,1950. .5. Lyons, D. J., and Bisgood, P. L.: An Analysis of the Lift Slope ofAerofoils of Small Aspect Ratio, Including Fins, With Design Charts wfor Aerofoils snd Cbntrol Surfaces. R. dv6nvJ08A=40 (HA= OK . .- . AA =/0 4a _ Ao u. 0 f 2 3 4 5 6 7(b) G = 10.Figure 9.- Concluded.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
