Bimodal unmanned vehicle: propulsion system integration and water/air interface testing

A multi-modal UAV capable of sustained aerial flight, locomotion in water and deployment from a tube filled with compressed air is under development. This paper covers the design and integration process of a CO2 thruster previously designed in a vehicle designed to fulfil mission requirements in terms of altitude and velocity after water/air transition. The thruster uses a common CO2 cartridge available off-the-shelf to accelerate water stored inside a water chamber for efficient and sustained thrust. Water is chosen as vectorial fluid since it is available from the surroundings. Analytical model, described in the paper, evaluates water to air transition phase in terms of trajectory, reached altitude and velocity. After thruster performances evaluation thanks to the analytical model, an experimental prototype was fabricated and tested for model validation. High speed camera is used to track vehicle transition and Kinovea software exports resulting data from a recorded video to spreadsheet formats for scientific study and post-processing. A comparison and discussion of the results as future work is also proposed with areas for improvement and development.