Flight Envelope Protection for a Fighter Aircraft

Abstract

An automatic scheme for the flight envelope protection of fighter aircraft is developed to prevent departure due to loss of control. The scheme involves taking control away from the pilot some time prior to an impending departure. The automatic recovery system then puts the aircraft into a safe attitude for recovery. The stability of the recovery trajectory is analysed within the flight envelope of the aircraft. The analysis demonstrates that the phugoid mode become critical for the recovery from low speed. The specific energy is demonstrating to be a much simple way of handling low speed recovery problems compare to existing solutions available.In addition,a unique command path design has been incorporated to assist automatic low speed recovery. The scheme is illustrated using the database of a high performance fighter aircraft with multiple redundant controls.