Hybrid drive soars to the airs

June 20, 2011 // By Christoph Hammerschmidt
Hybrid-electric drives are no longer a matter of cars only: At the Le Bourget air show, small plane manufacturer Diamond Aircraft shows what it claims to be the world's first airplane with a serial hybrid electric drive system. There are however significant differences to automotive drives.

The plane, a motor glider based on Diamond Aircraft's HK36 Super Dimona, features a serial hybrid drive - similar to an electric vehicle with range extender. The propeller is driven by a 70 kW electric motor made by Siemens. The electric energy required to drive this motor is generated by a generator which in turn is driven by a small 30 kW Wankel combustion engine from Austro Engine. An electronic converter, also provided by Siemens, supplies the electric motor with power from the battery and the generator.

Since the combustion engine always runs in its most efficient speed range, it consumers relatively little fuel. Increased power necessary for take-off and climb is provided by a battery, contributed by aviation group EADS. During the cruising phase when the electric motor consumers less power than produced by the combustion engine, the battery can be recharged. In contrast to automotive hybrid drives, in the current version no recuperation effect will be utilized. This however will be the case in the next version, a Siemens spokesperson explained.

The plane completed its maiden flight only on June 8, 2011, at the Wiener Neustadt airfield in Vienna. Since the hybrid power plant in its current form is rather heavy, the next development step will be to further optimize the entire drive train, Siemens said. Scientists of the company currently are working on a new electric motor that is expected to be much lighter than conventional ones.