Aerodynamic characteristics of aircraft under side gust

Abstract

Wind-tunnel tests were conducted to investigate the aerodynamic characteristics of an aircraft when exposed to side gust resulting from microburst windshear. External airstream was supplied through the test section side wall such that it was normal to the flight pathline and parallel to the ground. The effect of side gust was studied in terms of the model performance in undisturbed flight compared to its response during side flow. The model aerodynamic characteristics were examined at several sideslip angles as well as during straight flight. The wind-tunnel results of the straight-flight mode indicated that as side gust was introduced, there was a slight but consistent drop in lift, considerable accumulation of drag, increase in nose-up pitching moment, and constant lateral drift. The loss of lift became more appreciable at negative sideslip angles. In remedy, this situation was associated with a minimal amount of added-on drag. It was demonstrated that such loss of lift could be minimized by yawing the aircraft in the opposite direction, i.e., as the gust direction became closer to being head wind. However, this configuration of positive sideslip yielded higher accumulation of drag. Severe nose-up pitching moment was experienced during side gust exposure at negative sideslip orientations. It is found that while the trim condition was displaced, the stability margin was retained unaffected.