From 4 years ago, at an earlier stage of development:
Siemens - Electricity in the air
"A Siemens electric motor with an output of 70 kilowatts powers the propeller, drawing its energy from batteries mounted in the wings. Once the motor glider reaches its cruising altitude, the pilot switches on a small 30-kilowatt combustion engine. The sole purpose of this rotary engine is to provide energy for the electric motor through a generator, which simultaneously recharges the batteries."
Two years ago at the Paris Air Show, including video:
Siemens Hybrid Electric Aircraft Debuts in Paris [VIDEO] | Electric Vehicle News
"The plane's propeller is powered by a 70kW electric motor from Siemens. Electricity is supplied by a small Wankel engine from Austro Engine with a generator that functions solely as a power source. A Siemens converter supplies the electric motor with power from the battery and the generator. Fuel consumption is very low since the combustion engine always runs with a constant low output of 30kW. A battery system from EADS provides the increased power required during takeoff and climb."
"The next development step will be to further optimize the entire drive train. Siemens scientists are currently working on a new electric motor that is expected to be five times lighter than conventional drives. In two years, another aircraft is expected to be equipped with an ultra-light electric drive."
Press release and photos for the 2015 version:
World-record electric motor for aircraft - Siemens Global Website
World-record electric motor for aircraft
A bit more technical detail on this page:
https://www.siemens.com/innovation/e...ed-flight.html
"This is because an intelligent hybrid drive combining an electric motor and a combustion engine can use turbines that not only are significantly smaller than those of today but can also be continuously operated at peak efficiency during flight. Today’s turbines, by contrast, are designed to deliver a maximum level of power that is only required during takeoff and ascent. Aside from that, they only require 60 percent of their maximum output. 'With a kerosene-electric hybrid drive system, the turbine would run continuously at optimum power and provide energy, via a generator, for the electric motor powering the propeller,' Anton explains. 'During takeoff, extra energy would be provided by a battery.' "