Effects of Blowing Spanwise from the Tips of Low-Aspect Ratio Wings of Varying Taper Ratio, with Application to Improving STOL Capability of Fighter Aircraft.

Parametric low-speed wind tunnel testing of several low aspect ratio half-span wings featuring outboard-blowing wing-tip jets has been accomplished. This effort was performed to extend the existing information base regarding lift augmentation of low aspect ratio wings to encompass tapered wings suitable for application to high-performance fighter aircraft. At an angle of attack typical for fighter aircraft takeoff, operation of the wing-tip jets was found to augment the lift coefficient of aspect ratio two wings by 25 to 35, depending upon the value of the jet momentum coefficient and the wing taper ratio. At low angles of attack, the wing lift coefficients were augmented by as much as 120, but the amount of lift augmentation decreased in inverse proportion to wing angle of attack. The worth of blowing outboard from the wing tips of fighter aircraft as a means of enhancing STOL performance was assessed. Diverting 70 of the engine bypass airflow to the wing tips reduced predicted takeoff and landing distances by 15. Differential left-wing-tip-to-right-wing-tip modulation of the jet momentum can immediately produce up to 15,000 ft-lbs of additional roll control torque during low-speed landing approaches. Author