Design Studies for Hydrogen Fuel Cell Powered Unmanned Aerial Vehicles

Thomas Bradley, Blake Moffitt, Thomas Fuller, Dimitri Mavris, David Parekh
2008 26th AIAA Applied Aerodynamics Conference   unpublished
This paper presents two comparisons of design methods for fuel cell powered unmanned aerial vehicles. Previous studies of fuel cell powered aircraft have used design methods that contain intrinsic assumptions regarding the design of fuel cell powerplant and regarding the interactions between the powerplant and aircraft application. This study seeks to understand the effects of these design assumptions on the powerplant structure and the aircraft performance of fuel cell powered aircraft. A
more » ... ed aircraft. A comparison is constructed by developing a multidisciplinary modeling and design environment that does not contain the assumption suggested in previous studies. Design assumptions from previous studies can then be imposed on the more complete design environment to determine the performance costs and morphological changes caused by the design assumptions. In the first design study, results show that designing fuel cell powered aircraft using automotive-type fuel cell subsystem design rules leads to a low efficiency powerplant and a low performance aircraft in long-endurance and long-range UAV applications. The second design study shows that designing the long endurance aircraft powerplant towards maximum specific energy leads to suboptimal aircraft performance, especially for long-endurance UAV applications. I. Introduction HE long endurance unmanned aerial vehicle (UAV) has significant value as a low-cost, autonomous reconnaissance and remote sensing platform for research, commercial and military missions. Fuel cell powerplants are of interest in this application because of the potential to construct powerplants of high specific energy, low noise, low thermal signature, and improved environmental compatibility. Because of these performance advantages, fuel cells have recently found their first aviation applications as powerplants for small-scale long-endurance and long-range UAVs. Table 1 lists the demonstrated fuel cell powered UAVs known to the authors. In 2003, AeroVironment Inc., a vehicle design and manufacturing company in Monrovia, California, built and flew the first fuel cell powered aircraft. Its monopolar polymer electrolyte membrane (PEM) fuel cell system consumes hydrogen from a sodium borohydride reaction vessel. Between those first flights and the present, a number of researchers and commercial entities have developed fuel cell powered UAVs of increasing scale and capability. A majority of the demonstration aircraft have used a PEM fuel cell. A variety of hydrogen storage systems have been used including gaseous pressure vessels, chemical hydrates and low pressure cryogenic liquid hydrogen tanks. A notable technological outlier is the propane-fueled, solid-oxide fuel cell (SOFC) UAV that was constructed in
doi:10.2514/6.2008-6413 fatcat:rk3ustowarezjalbpz6coayjfa