Pitch Angle Control by Regenerative Air Brake for Electric Aircraft

Conventional aircraft use mechanical air brakes to adjust their descent paths; however, the lift-drag ratio cannot be continuously controlled, which results in zigzag descent paths. Previous research has shown that the negative thrust produced by the windmilling propeller works as a substitute air brake called the regenerative air brake. This paper proposes a new pitch angle control method using the regenerative air brake. The proposed method includes thrust estimation, negative thrust control, airspeed estimation, and pitch angle control using the pitching-jerk-based disturbance observer. The effectiveness of the proposed method is verified via simulations and experiments in a wind tunnel.