Not sure but I beleive the MK guys did a hover test for around 50 minutes (search Youtube)
Not to be confused with "flight time" though as actually flying outside suck more battery capacity than hovering inside
i am calculating some amps etc.
and theoretically i can flight 40 minute
with maxamp 11A battery
but nobody dont interested in this "flight time" :(
officially, I've heard about 10 hours
though, they cheated and used laser pointers focused on a solar panel on the bottom of the copter.
I beleive for self-contained power is less than an hour
its insane :)
is it posible? can transmit 12v 20A = 240W :)