Thrust and power characterization of a dual-domain aquatic sUAV electric propulsion system

Aquatic small uncrewed aerial vehicles (sUAVs) are vehicles that are capable of operating in both aquatic and aerial domains. To design aquatic sUAVs, validated propulsive performance prediction methods in both air and water are required. This work investigates the static performance of an aquatic sUAV electric propulsion system (electronic speed controller, motor, and propeller) both experimentally and through multidisciplinary modeling for the purpose of developing sufficiently accurate prediction methods. The results include three sets of experimental data for use in validation: thrust and electric power collected in both air and water using a custom load-cell set-up, thrust, power, and torque derived from a conventional thrust stand, and motor torque as a function of rotational velocity found using a hysteresis dynamometer. Three fluids models of varying fidelity, structural modeling, and electrical component modeling were used to further explore the experimental data and to identify model fidelity and adjustments necessary for accurate prediction of integrated performance. The results indicate that in addition to conventional approaches to fluid dynamic analysis and motor efficiency, it is necessary to account for blade pitch deformation, thermal effects, and low electronic speed controller efficiencies in off-design cases to accurately predict system performance in the aquatic domain.