A Note on the Evaluation of the Supersonic Downwash Integral

Summary To calculate tail loads in flight it is necessary to know the angle of downwash at all points of the tailplane for any given value of wing incidence. Current trends in aircraft design place the tailplane off the plane of the wing. There exist solutions for the downwash in the z=0 plane for a delta wing with subsonic leading edges. This note gives a form of integral suitable for numerical evaluation which determines the downwash in the plane of symmetry (y=0) of a delta wing with subsonic leading edges. This note also points out an apparent error in Ref. 4 by G. N. Ward and gives a closed form for the downwash at a point whose forward Mach cone totally includes an arrowhead wing with supersonic trailing edges and whose centre line coincides with the axis of the cone.