Low-boom and Low-drag Design Using Winglet

Abstract

A winglet design is discussed from the perspectives of sonic boom suppression and drag reduction at supersonic speeds. Design parameters such as dihedral and anhedral angles that were effective in reducing drag in previous studies on low-drag designs of a winglet at transonic and supersonic speeds were used in this study, and their effects on a low-boom design are examined herein. Non-dominated solutions with respect to sonic boom loudness and drag are explored using response surfaces and a genetic algorithm. Two characteristic winglets are selected from the solutions, and their drag and sonic boom characteristics are compared. Results showed that winglets affect sonic boom signatures through the shielding, cancellation, and reflection effects. The first two effects weaken expansion waves propagating to the ground, exerting a positive impact on rear boom suppression. In terms of drag reduction, the suction force of the winglet utilizing expansion waves on the upper surface of the wing should be enhanced, and the pitch trim change should be minimized to reduce trim drag. Based on these results, design guidelines to reduce both sonic boom loudness and drag are derived.