On the Effects of Wing-Gust Interactions and Wing Flap Deflections on the HTP Aerodynamics

Gust loads on aircraft are critical for the structural wing design. This paper investigates the impact of a critical vertical “1-cos” type gust event and different wing flap deflections on the aerodynamics of the Horizontal Tail Plane (HTP) and thus the pitching moment behavior of the aircraft. The wing flaps are deployed for the purpose of active gust load control and comprise spanwise segmented trailing edge flaps and leading edge flaps. URANS simulations are used for the simulations of two generic aircraft configurations with and without empennage at transonic flow conditions. The simulations reveal a significant impact of the wing-gust interaction and the wing flap deflections on the wing’s downwash angle. The change in the downwash affects the effective angle of attack at the HTP. However, the effects of the wing flap deflections on the HTP loads are less significant than the effect introduced by the reference gust. The deflections of the trailing and leading edge flaps on the wing are shown to be uncritical with regard to the pitching moment behavior of the aircraft. The gust and the wing flap induced maximum pitching moments can be significantly reduced via moderate elevator deflections on the HTP. A first approximation based on parametric 2D studies reveals a reduction by approx. 70% of the latter.