Utilization of differential thrust to regain lateral/directional stability of a commercial aircraft with a damaged vertical stabilizer

This paper studies the utilization of differential thrust to help a commercial aircraft with a damaged vertical stabilizer regain its lateral/directional stability. The vertical stabilizer is the key aerodynamic surface that provides an aircraft with its directional stability characteristic while the ailerons and rudder are the primary control surfaces that give the pilots the control authority of the yawing and banking maneuvers. In the event of an aircraft losing its entire vertical stabilizer, the consequential loss of the lateral/directional stability and control is likely to cause a fatal crash. In this paper, lateral/directional equations of motion are revisited to incorporate differential thrust as a control input. The engine dynamics of the jet aircraft is modeled as a system of differential equations with engine time constant and time delay terms to study the engine response time with respect to a differential thrust input. The novel differential thrust control module is then presented to map rudder input to differential thrust input. The investigation of the aircraft´s open loop system response is also presented. Finally, model reference adaptive control based on the Lyapunov stability approach is implemented to test the ability of the damaged aircraft to track the undamaged aircraft´s (reference) response in an extreme scenario.