http://www.gizmag.com/first-successful- ... ght/19716/
http://www.pprune.org/rotorheads/462709 ... s-off.html
The World’s first manned flight of a 100% electric powered helicopter was conducted on the 12th of August 2011, after 2 weeks of tethered flight tests. This machine, designed and test flown by Pascal Chretien, for the French based company Solution F, is the outcome of a remarkably short development period that was initiated in August 2010.
This ultra light coaxial helicopter weighs 170-Kg empty, including 60 Kg of high performance air-cooled Li-ion polymer batteries that can deliver 43 KW continuous, and 52 KW peak. The craft weighs 247-Kg at takeoff and offers 10 to 12 minutes flight time. To save weight, conventional cyclic and flight controls were replaced by a weight shifting system, as well as a specific design for rotor inertia, and blade pitch. Collective and yaw are achieved via electrical flight controls.
An advanced MOSFET based feather light drive train offers astounding 87.5% end to end efficiency, from batteries terminals to rotor mast.
This helicopter is a demonstrator intended to pave the way for hybrid rotary wing aircraft and is a test bed for new technologies. Flight envelope expansion is ongoing.