Here's a first: Serial hybrid electric drive in an airplane

One of the demonstration aircraft flown at the Paris Airshow last week was a modified Diamond Aircraft HK36 Super Dimona outfitted with an electric hybrid drive. The drive itself is analogous to that of the Chevy Volt in that an electric motor powers the prop and an internal combustion engine runs a generator to charge a battery if need be.

DA36 E-Star in flight.

The craft was developed by Siemens AG, Diamond Aircraft, and EADS. The two-seater motor glider, as it's called, completed its maiden flight a few weeks ago in Vienna, Austria. Siemens says the technology, which it eventually expects to put in larger aircraft, will cut fuel consumption and emissions by 25% compared to today's most efficient aircraft technology.

A view of the hybrid engine shows the electric motor (front) and ICE.

Siemens' Drive Technologies Div. has already used integrated drive trains like this one in such applications as powering boats.The electric motor in the plane is a 70-kW model from Siemens, which also supplies the inverter.The internal combustion engine running the generator is a Wankel from Austro Engine. Siemens says the fuel consumption is low because the ICE always runs with a constant low output of 30 kW. A battery system from EADS provides a power boost during takeoff and climb. The battery recharges during the cruising phase.

Siemens says it isn't done optimizing the drive train. It is currently working on a new electric motor expected to be five times lighter than conventional drives. It expects to fly another aircraft in two years powered by this lighter electric drive.

Siemens put out a press release on the plane that includes video of it flying at the Paris show: http://www.siemens.com/press/en/pressrelease/?press=/en/pressrelease/2011/corporate_communication/axx20110666.htm