WING AND TAIL SURFACES

An investigationwas made to determinethe effectsof vertical-tail sizeand lengthand of fuselageshapeand lengthon the lateralstatic stabilitycharacteristicsof a modelwith wing and verticsltailshaving the quarter-chordlinessweptback ~SO. The resultsindicatethat the directional.instabili ~ of the variousisolatedfuselageswas abouttwo-thirdsas largeas thatpredictedby classicalth,eorg.A reductionin area of verticaltails (geometricaspectratiokept constant)attached to a givenfuselageresultedin an increasein the effectiveaspectratio of the verticaltailfor the rangeof tail sizesconsidered.Simple analyticalconsiderationsindicate,however,thatfor tail sizesbelow the rangeinvestigated,the oppositeeffectwouldbe expected. For the fuselage-tsilcombinationsinvestigated,the tail effec-tivenessusuallydecreasedwith increasingangleof attack,withthe greatestrate of decreaseoccurringat anglesof attackgreaterthan about160. The wing-fuselageinterferencefor the midwingarrangementsinves-tigatedwas only slightlyaffectedby the shapeof the fuselageand tendedto increaseslightlythe directionalstabilityof the’combination. The interferenceffectsof the wing tendedto decreasethe vertical-tail effectiveness,particularlyat high anglesof attack. The large effectsobservedwere attributedto a partiallystalledconditionof the wing.