Computer Study of a Jet Flap ASTVOL “Harrier” 841457
A study of the costs/benefits trade-off was conducted for an Advanced Supersonic Short Takeoff and Vertical Landing (ASTOVL) aircraft incorporating a jet flap. The data used were the theory of jet flaps and high-aspect-ratio nozzles, experience with the McDonnell V/STOL aircraft study performed for NASA Ames Research Center in February 1982, and a high-performance aircraft-synthesis program (ACSYNT).
The methodology was to accurately model the McDonnell supersonic Harrier V/STOL aircraft design on ACSYNT, and then modify the design by both adding high aspect-ratio (AR) nozzles in place of the rear (core-flow) nozzles on the Pegasus-type turbofan engine, and integrating these nozzles on each wing's trailing edge, thus creating a jet flap. The predicted performance advantages (increase in CLmax with flap deflection and horizontal thrust recovery) were traded off against the disadvantages (additional weight and thrust loss due to ducting) on two representative missions.