I was thinking about this a few years back, but other stuff needs to be done first and I never really did any testing.
So, I'll throw this out there
A small, 1-2 place craft. Put a high compressed tank of oxygen in place of the engine. Remove fuel tank to save
weight and anything else that is not needed to save on weight.
Route the air from the compressed tank of air up thru the center mask
into the rotor blades, to the tips of the blade, than out thru the trailing edge.
The compressed air will turn the blades.
No torque = no tail rotor needed.
Would this be feasible?
How long would the air last?
Worth looking into?
Surely someone has thought of this before me.