The interference on a three-dimensional jet-flap wing in a closed wind tunnel

Abstract

The classical theory of wind-tunnel interference is extended to cover interference on the effectiveness of a full-span jet flap issuing from the trailing edge of a high aspect ratio unswept wing. It is shown that, for small constraint, corrections ΔCj and Δα must be added to the observed jet momentum coefficient and wing incidence, respectively. These corrections are derived, together with the corresponding corrections to the observed lift and thrust coefficients. Corrections to the observed downwash field over a limited interval downstream of the trailing edge of the wing are also derived. These lead to a corrected jet path and a downward displacement of the downwash pattern, in addition to the direct increment to the observed downwash. Corresponding corrections to tail height and setting are also given.