Dont think the mythbusters even need bother! I think if it were for real the rotor blades would cone up so much they would likley snap or deform,
and if you gould get the engine up and running in time (another achievment in itself whilst the helicopter spins around like god knows what) you would never get the blades to level out and achieve any lift.
An ULTRA extreme case of Vortex ring!!!
Not possible
MADY