Benet,
I suggest that you have a look at the current electric radio controlled helicopters beginning to enter the market. They do not rely on Li-Cells but on a new type of cell that have a greatly improved power-density (the name escapes me). These machines have an endurance of about 7 minutes. WOW!
The all-electric-rotorcraft is not a new idea, the combination of modern gas turbines with shaft mounted integral high-speed electrical generators powering electrical motors via power-electronics has been bounced around by most of the big companies for years. Interestingly, the major motivation of this move would be an increase in system reliability rather than a performance/weight benefit. We are currently waiting for the technology to catch up with the concept, then i'm sure this stuff will start to make an appearance in the aircraft.
Hope this helps,
CRAN
