Flight measurements of wing-tip vortex motion near the ground

Abstract

Tests have been made to measure the movement of the wing tip vortices from a Hunter aircraft flying at 170 knots approximately 35 feet above a runway, in a variety of wind conditions. Measurements were limited to a maximum time of 20 seconds after vortex generation. During the period the theoretical predictions presented are in good general agreement with the observed motions; however significant differences did occur. There was no clear indication as to whether the vortices decayed more rapidly in the presence of the ground and atmospheric turbulence, than would have been expected from earlier measurements away from the ground in calm air. Limited tests were also made to study the vortex mutual interaction away from the ground.