Design of a Fuel Cell Powered Blended Wing Body UAV

Small-scale electrically powered Unmanned Aerial Vehicles (UAVs) are currently in use for a variety of reconnaissance and remote sensing missions. For these missions, electrical propulsion is generally preferred over small internal combustion engines because of the low noise and IR signature, low vibration levels, ease of operational support, and physical robustness. A desire for longer endurance than is available from the current generation of batteries has motivated the development of fuel cell based hybrid electrical propulsion systems. These advanced powerplant designs often include implementation challenges that will require new development methods and tools. Fuel cells generally lead to very low fuel weight at a high specific energy (Wh/kg) but have low specific power (W/kg). A high specific power is required to improve aircraft performance and manoeuvrability. Aircraft concepts powered solely by fuel cells therefore require both extremely lightweight airframes with a large internal volume and low-power payloads, which remains a challenge for conventional airframe designs. A blended-wing-body (BWB) airframe has high aerodynamic and structural efficiencies, which therefore seem ideally suited for this new generation of power-plants.This paper presents the development and testing of a novel BWB fuel-cell powered UAV. The paper first describes the initial design steps that led to the current airframe design. The Mark 1 platform has been developed, with a half-scale model built and currently being flight-tested. Based on the flight test results, the airframe will be scaled up and optimised to accommodate the fuel-cell and its associated systems. This aircraft will then be tested with a standard electrical propulsion system to determine the airworthiness with the restricted fuel cell power output as well as the design of the take-off boost system. This paper reports on the design, analyses, and preliminary testing of a fuel cell powered BWB UAV.Copyright © 2012 by ASME