Hydrogen Fuels BoeingÂ’s Long-distance UAV, Â“Phantom EyeÂ”
Apr 10, 2013
The Phantom Eye, a hydrogen-powered, airborne system being developed by Boeing, demonstrates the inherent efficiency and versatility of hydrogen fuel. The unmanned aircraft, which is designed to serve as a communications relay hub, will be capable of continuous flight for four days and reach 65,000 feetall while producing zero emissions.
As one of the most efficient fuels by weight, hydrogen is ideal in long range, aerial applications. According to Boeing, the Phantom Eye has proven the exceptional fuel economy of the liquid hydrogen propulsion system. The 9,800 lb aircraft is kept aloft with two 2.3-liter liquid hydrogen combustion engines, producing a combined 300 horsepower. According to a Boeing representative, the engines are modified versions of those found in the Ford Ranger, each with three-stage turbochargers to compress ambient air for high-altitude flight in the stratosphere. Fuel is stored in two 8-foot diameter cryogenic tanks, and has roughly three times the energy content of aviation fuel by weight.
The Phantom Eye has completed two autonomous test flights during its development process. The first test flight took place in June 2012, with the aircraft reaching 4,080 feet and a cruising speed of 62 knots. During its second test flight in February 2013, the Phantom Eye kept aloft for 66 minutes and reached more than 8,000 feet at the same cruising speed. Afterwards, Boeing Phantom Works President Darryl Davis said, No other system holds the promise of offering on-demand, persistent [intelligence, surveillance and reconnaissance] and communications to any region in the world.
Since the engines have performed very well in test flights, Boeing is exploring the possibility of adapting the hydrogen propulsion technology to larger applications. The HALE concept, based on the Phantom Eye, would be capable of flying for at least seven days without refueling while carrying payloads in excess of 2,000 lbs.
While fuel cells are not slated for widespread use in aviation propulsion, airports and aviation companies are recognizing that they can reduce local emissions. Fuel cell systems have been demonstrated in hydraulic aircraft systems and ground systems, including tow tractors and baggage vehicles. Fuel cells could also be used in cargo reloading, electrical main engine start, air conditioning, and supply potable, heated water.