GALCIT Colloquium

Longitudinal instability plagues the aerodynamic design of aircraft having swept back wings of high aspect ratio. Consequently, competing designs of contemporary commercial aircraft wings are almost identical, suggesting that the conventional design practices attained their optimal limit. The introduction of Active Flow Control (AFC) to preliminary design represents a promising solution to this stability problem provided it would not be considered as an "Add-On" to a predetermined wing form.  This change in approach requires one to consider concomitantly two lumped parameters: (i) the inviscid flow around a solid body, (ii) the effect of AFC on this flow that might bring about a change in the shape of the solid body considered. Preliminary experiments carried out on a tailless aircraft model indicate how AFC has to be tailored in order to maintain the aerodynamic center (neutral point) at a constant location in-spite of an increase in incidence that is often mandated on landing approach. The tailored use of AFC provides the needed control authority without deflecting any control surface. In short, AFC can change the aerodynamic characteristics of a wing. It may increase the lift and enhance the effectiveness of control surfaces.