The world's first piloted aircraft capable of taking to the air using only power from hydrogen fuel cells has flown, producing zero carbon dioxide emissions during the landmark mission.
The Antares DLR-H2 - developed by German aerospace centre DLR together with Lange Aviation, BASF Fuel Cells and Denmark's Serenergy - has a range of 750km (390nm) and can fly for 5h at maximum flying speeds of about 90kt (170km/h).
The DLR says it has improved fuel cell performance capabilities and efficiency to such an extent that the motor glider can take off using fuel cell power alone.
"This enables us to demonstrate the true potential of this technology," says the DLR's Johann-Dietrich Wörner, who concedes however that fuel cell use constitutes a more likely alternative to existing on-board energy systems than main propulsion alternatives.
The system uses hydrogen as its fuel, which is converted into electrical energy in a direct, electrochemical reaction with oxygen in the ambient air, without any combustion occurring and producing only water.
To accommodate the fuel cell and the hydrogen supply, two additional external load carriers weighing 100kg (220lb) were slung under the specially reinforced wings whose aeroelastic properties had to be reconfigured to safeguard flight stability.
The fuel cell system used to power the Antares delivers up to 25kW of electrical power but operates at an efficiency level of about 52% when the aircraft is flying in a straight line, which requires around 10kW.
The total efficiency of the drive system from tank to powertrain, including the propeller, is around 44%, making it about twice as efficient as conventional propulsion technologies based on combustion processes.
Another innovation is the way its fuel cell is connected to the main electric motor that powers the aircraft. Developed jointly with Lange Aviation and the College of Advanced Technology in Berne/Biel, it is capable of taking in and controlling voltages from 188 to 400, increasing efficiency and reliability, while cutting maintenance costs.
The Antares DLR-H2 will be based at Lufthansa Technik in Hamburg where, over the next three years, it will be acting as a flying test platform for the fuel cell test activities of DLR as part of its Fuel Cell Labs project.