Fuel Cell Sizing for a UAV with Intermeshing Rotors using a Genetic Algorithm for NDARC Rotor Performance Calibration

Abstract

Hydrogen fuel cell driven electric vertical flight is a current area of research and an alternative to battery based electric flight. This paper presents the models and methods used to size the hydrogen power plant and tanks of an unmanned helicopter named AREA. The battery electric power system of AREA will be converted to hydrogen power in the future. The goal of the conversion is to increase the flight time from the current 25 minutes to more than one hour. The design is performed using the NDARC preliminary design software. AREA uses intermeshing rotors. First, the necessary settings are found to model intermeshing rotors in NDARC, as this rotor concept is not natively supported by NDARC. Second, the rotor performance model is calibrated based on CAMRAD II simulations and flight test data. For this purpose, an automated calibration tool is developed using a genetic algorithm for robust calibration results. Third, the hydrogen system components are modeled and sized for the planned 60 min cruise test mission at maximum endurance speed. The results show that the nominal fuel cell power should be 3.8 kW and 280 g of hydrogen are required. The sized hydrogen system weighs approximately 20 kg.