AeroVironment (AV), a California-based energy and electric vehicle development company, has announced the first hydrogen-powered aircraft. In January 2011, the company’s new unmanned aerial vehicle (UAV), the Global Observer, completed its first flight.
Hydrogen-powered aircraft are based on the use of hydrogen rather than hydrogen-containing fuel chemicals, like gasoline or jet fuel. The term refers both to fuel cell-powered aircraft and to aircraft which mix hydrogen in a combustion-based jet engine. In both cases, the byproduct is clean water. Hydrogen-powered flight faces many of the same problems as hydrogen-powered vehicles, which were also eagerly anticipated a decade or more ago but have yet to emerge as competitors to the internal combustion engine. A hydrogen-powered jet engine in theory is more capable than a kerosene-powered one, because hydrogen can provide more energy from a smaller mass of fuel. However, in order for this to work, the vehicle must have some means of storing liquid hydrogen, which can only be maintained at exceptionally low temperatures.
The initial prototype Global Observer had a 50-foot wingspan and is expected to be able to carry loads up to 1000 pounds. In early planning documents, the company suggested that a very lightweight vehicle, combined with the great potential of hydrogen fuel, meant the new design could stay aloft for a week. Allowing one week for servicing on the ground, this means that just two Global Observers working in tandem could provide a constant presence in an area of interest, to facilitate communications or surveillance. This holds obvious interest for the military.
2011’s maiden flight of the Global Observer is the product of years of research. In 2005, a Global Observer prototype made its first test flight at Yuma, AZ, a U.S. Army testing facility. The latest test flight features a much larger, revamped Global Observer with a wingspan of 175 feet, which the company believes will meet the same week-long flight specification (although the payload has fallen to 400 pounds). On this occasion, it flew four hours at 5000 feet above sea level to test flight systems, and then returned to land at Edwards Air Force Base, also in California.
According to Defense Industry Daily, so far the Global Observer development project has received $120 million in government funding, mostly from various defense agencies. AeroVironment has been developing clean vehicles since the 1970s, including the first successful human-powered aircraft (the Gossamer Condor,) and a number of solar-powered aircraft, including the Pathfinder, Centurion, and Helios. Helios’ prototype is a UAV, which set a world altitude record when it reached 96,863 feet in 2001.