Transonic flutter model study of a supercritical wing and winglet

A scaled flutter model—a 1/6.5-size, semispan version of a supercritical wing (SCW) proposed for an executive-jet-transport airplane—was tested cantilever-mounted in the Langley Transonic Dynamics Tunnel with a normal wingtip, a wingtip with winglet, and a normal wingtip ballasted to simulate the winglet mass properties. Flutter and aerodynamic data were acquired at Mach numbers (M) from 0.6 to 0.95. The measured transonic flutter speed boundary for each wingtip configuration had roughly the same shape with a minimum flutter speed near Af= 0.82! The winglet addition and wingtip mass ballast decreased the wing flutter speed by about 7 and .5%, respectively; thus the winglet effect on flutter was about equally a mass effect as well as aerodynamic effect. Flutter characteristics calculated using a doublet-lattic e analysis (which included interference effects) were in good agreement with experimental results up to M =0.82. Comparisons of measured static aerodynamic data with predicted data indicated that the model was aerodynamically representative of the airplane SCW.