Aircraft Cruise Drag Reduction Through Variable Camber Using Existing Control Surfaces

Abstract

The ability to morph the shape of an aircraft wing to optimize performance is widely accepted as a path to improved aircraft efficiency. A simpler approach is to change the wing camber using existing control surfaces. In this work, a Reynolds-averaged Navier–Stokes-based aerodynamic shape optimization methodology is applied to the design of a business jet with variable camber. Variable camber is achieved using the three existing control surfaces on each wing. Multipoint optimization is performed over a range of cruise operating conditions with and without variable camber. Variable camber is found to yield a reduction in drag of approximately 3–11 counts, or 1–5%, over a range of cruise conditions, with the largest reductions seen at lower lift coefficients. The control surface deflections are used to reduce the wing camber at lower lift cruise conditions, leading to an increase in the aircraft angle of attack across most operating points. The increased angles of attack transfer lift to the fuselage, which enables reductions in induced, wave, and trim drag. This additional drag reduction mechanism has not been identified in previous studies and cannot be seen in optimizations that do not include the fuselage and a trim constraint.