New jet-pack patent propels with water

Raymond Li's terrifying contraption, described as a "personal propulsion device," just became U.S. Patent 7,258,301. Powered by a clever system of conduits that lead to independently pivoting thrust nozzles, it's designed to provide inherent stability using "throttle controls and the like."
A rocket pack, you mean? Ah, but no! From the inventor's filing:

Typically, flight packs include propulsion devices such as propellers, rotor
blades, or rockets, which often require a highly flammable fuel in order to
generate sufficient thrust for flight. In addition to having a reservoir of
volatile fluid attached to the body of a pilot, the close proximity of the
propeller, rotor blades, or rocket exhaust to the pilot further poses
significant safety risks. ... As an alternative to employing the combustion of
volatile fluids to directly generate thrust, the high-pressurization of
non-flammable fluids, such as water, has been proposed to create sufficient
thrust in order to achieve flight.

Any flammable stuff, therefore, only ever sees the dark interior of a combustion engine floating on the water, powering the pump. No rotor blades, no hot gases (except the motor's exhaust), just plumes of pressurized water.