Sizing of a solar/hydrogen system for high altitude long endurance aircrafts

• An easy tool for the proper sizing of the solar/hydrogen system is proposed.
• The system's global efficacy is calculated by means of an analytical energy balance.
• Results showed that a solar/hydrogen system provide greater efficacy to HALE aircraft.
• As a case of study, three selected HALE aircrafts projects were analyzed.

High altitude long endurance (HALE) aircrafts are aerial platforms operating in the stratosphere, providing relay services for wireless communication networks. These platforms are an alternative to increase the effectiveness of future communication. Nevertheless, the power system is a key part that determines the implementation and feasibility of these platforms. One effective and renewable option to power an HALE aircraft is a photovoltaic system (PVS) with hydrogen storage. In this paper, the simulation of the solar/hydrogen closed loop system is carried out for a parametric combination of the subsystems power. Power consumption of the propeller was determined as a function of the aircraft weight in steady flight and in still air. In order to obtain the optimal nominal powers the efficacies are calculated at hourly intervals over the course of the year by means of an analytical energy balance. The proposed method was implemented in an algorithm, which allows fast estimation of the actual time of flight and the system efficiency. Finally, the energy system of three HALE aircrafts was analyzed in relation of their wing area and total and empty mass.

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