21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-1.10.3

PNEUMATIC YAW CONTROL AT HIGH ANGLE OF ATTACK FOR LOW OBSERVABILITY COMBAT AIRCRAFT

Garry K. P., Williams S. P.
Cranfield University, United Kingdom

Keywords: pneumatic yaw control, high angle of attack, low observability, combat aircraft

A series of low speed wind tunnel tests have been conducted using a generic combat aircraft model to investigate pneumatic methods of yaw control at high angle of attack. The results show that blowing air through slots near the forebody apex can produce significant yawing moment and side force. Light sheet flow visualisation shows that blowing modifies the forebody shear layer trajectory in such a way as to induce forebody vortex asymmetry at up to 45 degrees angle of attack. Coupling with the wing vortex system induces large rolling moments within certain incidence ranges. Yawing moment increases with blowing momentum coefficient up to a-Critical value above which the blowing side forebody vortex bursts and further yawing moment increments are developed through blowing thrust effects alone. Variations in both forebody geometry and blowing direction were found to have a Significant effect on the levels of yawing moment achieved.

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