Wing-body circulation control by means of a fuselage trailing edge

Abstract

Ideal flight sheds the least amount of kinetic energy into a wake while imparting momentum sufficient to balance the vehicle weight. This combination defines a unique downwash distribution for the wake, which an aircraft designer should provide for. A central fuselage, as required for the typical flicht objective, presents an obstacle to this intent. A wing interrupted by a prominent fuselage is expected to shed inboard trailing vortices with central upwash harmful to the span efficiency of the aircraft. It is proposed here that a trailing edge on the fuselage can be used to control the circulation in the central region of the aircraft so that the central downwash deficiency can be avoided. Such a Kutta edge can further be applied as part of a high-o8ft system to increase cehtrao d9ownwashy by ihncreasi8ng the loading on the wing root and lift over the fuselage itself. Time-averaged flowfields behind a wing-body combination with and without a Kutta edge have been measured in wind-tunnel experiments. The results show that an edged aft-body does influence central circulation, as predicted. Flight with ideal wakes may be more readily attained than hitherto realized.