Latitude Engineering’s Hybrid Quadrotor UAV uses its four electric-motor-driven propellers for vertical take-off and landing and its gas-engine-driven push-prop for cruising at 40 knots:
“When you make a tilt-rotor all electric powered, you need tons of batteries if you want endurance,” Carlos explains. “If you want a high-endurance gas tilt-rotor you need (for the sake of argument) a super-charged V8 to take off, while during forward flight all you need is a tiny little inline 4 … vertical take-off and forward flight have pretty much mutually exclusive requirements when it comes to power sources.”
With the HQ, he says, “you are always flying with the correct power source for the job, VTOL or conventional flight.”
So, we have to shoot out both the gas motor and the batteries to bring this thing down?
It could drop the spent batteries after takeoff: BATO.
A power cord hooked up to an offboard power source — batteries or a generator — could serve the purpose of a catapult and reduce the need for batteries.
Also, an onboard generator could harness the gas engine for take-off and landing — but that wouldn’t have the same useful redundancy that Bob pointed out.