Vortex Flow Aerodynamic Challenges in the Design Space for Future Fighter Aircraft

The future air-combat scenery sees an emerging change in air-combat tactics due to stealth and modern missiles. Fast, visual encounters could be decided by very rapid instantaneous maneuvers at high angle-of-attack and transonic speed for shooting advantages being finalized by rapid missile exchanges. Controlled vortex flows also at higher transonic speeds must be mastered for controlled motions about all three axis. The aircraft planform, wing-sweep and the leading-edge type have to be arranged for the mutual benefit of these complex flows throughout the flight envelope also regarding signature considerations. Often controlled flight limits are reached at sideslip conditions. Here asymmetric vortex instabilities cause unstable rolling moments together with adverse yaw. To push these limits an extended understanding of vortex separation, their interaction and breakdown is necessary. The probing of the design aerodynamic characteristics are to be assisted by modern flow simulation tools to be validated on the basis of appropriate physical understanding via sophisticated test-facilities.