Design and field test of a foldable wing unmanned aerial-underwater vehicle

This paper presents the design and field test of a foldable wing unmanned aerial-underwater vehicle (UAUV). The vehicle can complete diving and air operations, and still have the ability of multiple trans-medium water egress and ingress under the condition of carrying mission load during a single flight. The wings can be folded back for drag reduction in underwater sailing and water egress, and unfolded to provide lift for flight after water egress. This paper presents the major components and system design of the vehicle, including the overall structure of the vehicle, the design of the mechanism for self-locking and quick-folding, the design of the electrical system, the selection of the propulsion system, and analyzes the performance gains from foldable wings and foldable propellers. Then the trans-medium field test was introduced, and the analysis and discussion were conducted for the four typical operating conditions of the vehicle, including water sailing, aerial flight, water egress and water ingress. Furthermore, the endurance performance under the corresponding operating conditions is estimated based on experimental data and the current battery energy carried. The presence of foldable wings and a large pitch angle water egress strategy reduces the thrust-to-weight ratio requirement for the vehicle. The results of the field tests can provide important experience and data support for the subsequent application-oriented UAUVs.