Diamond Aircraft has test-flown a hybrid twin-engine aeroplane developed in conjunction with Siemans.
The modified DA40 flew on 31 October from the Diamond headquarters in Wiener Neustadt, Austria. During the 20 minute flight, the aircraft was flown to 3000 feet and up to 130 KTAS.
"This is the first serial-hybrid electric plane in the world with two electrically powered free-stream propellers and one combustion engine," said Dr Frank Anton, Executive Vice President eAircraft at Siemens AG.
"A distributed propulsion architecture opens entirely new possibilities for the design of highly efficient planes – and we have now proven its technical feasibility."
In development since 2013, the aircraft was reconfigured to support a hybrid electric powertrain. In this system, one combustion engine powers two independent electric drive systems consisting of one motor, battery and inverter each.
Diamond mounted the two electric engines mounted on forward canards, which combined can generate 150kW of take-off power. A diesel generator located in the nose can provide up to 110kW of power and two 2kWh batteries in the rear passenger compartment act as an energy storage buffer.
With a dedicated power lever, the pilot can control the energy flow between the generator, batteries and motor. The pilot can select either pure electric mode (generator off), cruise mode (generator provides all power to the motor), and charge mode (generator charges the batteries).
The aircraft has an endurance of approximately 30 minutes if running purely on electrical power, but the hybrid system extends that to five hours.
"Serial-hybrid electric propulsion systems and distributed propulsion architectures for us are the key to a more sustainable flight future also in higher power classes," Anton said.
"The Diamond flying testbed will help us to understand the requirements for these new propulsion technologies and to be prepared for the challenges of larger-scale applications."
This is not the first hybrid electric aircraft developed by a collaboration between Siemens and Diamond. In 2009, the two companies successfully demonstrated a hybrid powertrain in the DA36 E-Star.