Investigation of the Pitch Stability of an Underwater Glider that uses the Passive Flapping- Foil Glide Concept

In the present paper, the pitch stability of an underwater glider based on the passive flapping-foil glide concept is investigated. Throughout the investigations, criteria for correct trim adjustment and pitch stability are established, and a calculation model for the theoretical stability analysis is introduced. Subsequently, a demonstrator for the considered system is presented, and the necessary parameters for the calculation are introduced. Based on the established relationships and presented information, the demonstrator's pitch stability is investigated theoretically, and the results are presented and discussed. Finally, a summary, including an outlook, is provided. The investigations show that the system remains stable in the horizontal trim position both in the static state and at maximum speed during descent and ascent phases. The system concept is thus suitable for energy-efficient gliding processes without the need for active pitch stabilization.