Effects of Frost on Wing Aerodynamics and Take-Off Performance

Computations were done to predict the effects of various extents of frost coverage on the airfoil, wing, and takeoff performance of two hypothetical aircraft, a small light aircraft and a large transport aircraft. Airfoil performance was computed using rough wall boundary layer calculations coupled to an inviscid vortex panel method which includes a capacity for modeling stalled flow conditions. The roughness parameters determined for one of the frost samples were used for this purpose. A lifting line analysis was used to determine wing performance from the airfoil results. The results indicate that frost having an effective height of only 0.4 mm in the leading edge region of a wing can cause serious performance degradation even for a very large aircraft. On the other hand, frost coverage beginning well down stream of the suction peak, for example at about one/quarter chord, was predicted to have little effect.