Transonic flutter investigation of models of a proposed variable-sweep wing

i n v e s t i g a t i o n has been made of models which were dynamically and e l a s t i c a l l y scaled from a proposed variable-sweep wing design which had an aspect r a t i o of 7 ( a t minimum sweep), a t a p e r r a t i o of 0.2, a f i x e d root section having a 65' sweepback angle, and a movable outboard panel.8The e l a s t i c r e s t r a i n t a t t h e pivot vas simulated on t h e models.Models of t h e proposed wing and models of aspect r a t i o 5, formed by c u t t i n g off t h e t i p s from the proposed-wing models, were invest i g a t e d with t h e outboard wing panel a t leading-edge sweepback angles of 20°, 45O, 6 5 O , and 8 0 ' .The f l u t t e r t e s t s were conducted i n t h e Langley t r a n s o n i c blowdown tunnel a t Mach numbers from about 0.7 t o 1.25.F l u t t e r boundaries were obtained f o r a l l configurations except the 80' swept, aspect-ratio-?wing which w a s f l u t t e r -f r e e within t h e t e s t limits a v a i l a b l e i n t h e tunnel.I n general, the.t r a n s o n i c f l u t t e r bound- a r i e s obtained w e r e t y p i c a l of those f o r wings of moderate aspect r a t i o .A t subsonic Mach numbers, increasing t h e sweep angle of a wing increased t h e dynamic pressure required f o r f l u t t e r .The r e s u l t s suggest t h a t s t i f f n e s s requirements established by f l u t t e r considerations may be minimized by f l i g h t programing of t h e sweepback angle f o r wings similar t o t h e present two designs.