The evaluation of downwash at large spanwise distances from a vortex lattice

Abstract

This note explains an improved numerical method of evaluating the contributions to the downwash at moderate or large spanwise distances from a vortex lattice. By allowing freedom of choice of ihe chordwise positions of the discrete vortices of the lattice, it is possible to select three definite chordwise positions and strengths of vortices at, each of these positions dependent on the chordwise pressure distribution, so as to determine the downwash with good accuracy for three particular pressure distributions proportional to cot ½θ, sin θ and sin 2θ. The corresponding chordwise loading factors have also been evaluated for deflected flaps.