Sliding-Mode Control and Strategic Thrust-Vectoring Based Aircraft Flat Spin Recovery With Altitude Loss Minimization

Spin recovery from a fully-developed-oscillatory-stable-flat spin is performed in this article using thrust vector control (TVC) and compared with the conventional mode of recovery. TVC dynamics is modeled and then added to the standard aircraft dynamics. TVC command is designed as a function of angle of attack in the pitch and yaw direction and optimally used with aircraft primary controls (APCs). The APC is designed using the sliding-mode control technique. The spin recovery profile is demonstrated on F-18 high alpha research vehicle to test the efficacy of the proposed algorithm. Results show that with the combined strategic use of TVC and APC, spin recovery time is drastically reduced because of reduced saturation of APC. Thus, altitude decrease during spin recovery also reduces, thereby gaining on final exit altitude to level flight, compared to recovery using only APC. Thus, TVC is proven in this article to be a powerful corrective contributor to spin recovery, increasing margin of safety in terms of excessive altitude loss.