Tucked in between the jumbo jets and military demonstrations at the Paris Air Show this week is a small motorglider featuring the first serial hybrid electric drive found in an airplane. Like the Chevy Volt, the airplane is directly powered by an electric motor. But the electric motor can run on battery power, or it can be powered by a small gasoline engine when the batteries run out.
“We want to cut fuel consumption and emissions by 25 percent” said Dr. Frank Anton of Siemens in a press release, one of the companies developing the new aircraft power plant.
Siemens, together with the aerospace giant EADS and Diamond Aircraft of Austria are developing the serial hybrid drive in the DA36 E-Star, a composite two seat general aviation aircraft. The company hopes the technology can be easily scaled to larger aircraft.
In addition to reducing fuel consumption, the hybrid drive can also greatly reduce noise heard by people on the ground.
The noisiest part of a typical flight takes place during takeoff when airplanes are using maximum power close to the ground. The serial hybrid drive allows the pilot to takeoff using only electric power, greatly reducing the overall noise heard on the ground, or in the airplane as we discovered when flying an electric airplane last year.
Under the cowling of the DA36 E-Star shows the serial hybrid electric drive.
The demonstrator in Paris completed its first flight in Austria on June 8. It uses a 94 horsepower electric motor from Siemens to power the propeller. The batteries are used during takeoff and climb. During cruise a relatively modest 40 horsepower Wankel rotary engine with a generator acts as the power source for the electric motor.
Like other electric powered aircraft, the DA36 E-Star can only carry a range limiting number of batteries, reducing the all electric range of the aircraft. But Siemens is already working on the next generation electric motor which it expects to be significantly lighter than the version currently being used. Other improvements to the drive train, as well as the always hoped for improvements in battery technology should allow for an even greater reduction in fuel use during a flight.
Like its automotive cousins, electric aircraft are still striving for extended range. Strictly battery powered electric aircraft are able to make flights over an hour now, a bit of a milestone because it allows for the possibility of using electric airplanes for flight instruction. Because of the weight of the batteries, there are limitations to dramatically extending the range using only battery power based on what is currently available.
Back in 2008, Boeing used a similar motor glider from Diamond Aircraft as a test bed for a hydrogen fuel cell powered electric airplane. Two years later it unveiled a hydrogen fueled unmanned aircraft to be used by the military.
None of the companies involved with the new serial hybrid drive DA36 announced any plans for the future use of the new drive train beyond saying in the long term it will also be used in large scale aircraft.