A few years ago EADS was touting
eCO2avia, a diesel-electric solution with two
OPOC diesels charging two batteries via electric generators, and with electric motors driving the rotors. The concept, which was previously mentioned in the
'Electric Sikorsky' thread, had the potential to free designers from the traditional layout constraints of mechanical transmission helicopters:
The hybrid system architecture allows the main rotor and its electrical drive to be tilted forward during cruise flight. This enables the helicopter’s fuselage to remain at its optimum alignment with the airstream, minimizing aerodynamic drag and thereby reducing the power demand and the fuel consumption. Since the tail rotor has no mechanical linkage to the main rotor and its power source, it can be turned off at higher speeds. During these flight phases, stability and control as well as balancing of the rotor torque are provided by the aerodynamic properties of the helicopter’s tail fin and rudder.
[Source]
The concept went 'quiet' shortly after its unveiling, though interestingly Airbus and Siemens just signed an
agreement to cooperate on the field of hybrid electric propulsion systems.
I/C