A technician wheels an experimental one-person helicopter called firebird out of a large gray hangar at London Southend Airport in England. It has a bare-bones look, as if cobbled together in someone's garage. A red tubular-steel frame encloses a single exposed seat and a pair of fuel tanks, hung beneath a two-bladed rotor. That's it. No fuselage, no complicated controls, not even an engine.
Soon a test pilot wearing a crash helmet and overalls climbs in and works a hand pump that forces hydrogen peroxide up to the rotor, where the liquid flows along pipes embedded in the blades. At the tip of each blade is a tiny, one-pound rocket motor. When the fuel enters the motors, it hits layers of silver and stainless steel mesh, causing the hydrogen peroxide (H2O2) to decompose explosively into steam (H2O) and oxygen (O2). The process unleashes about 100 horsepower from each unit— a far superior power-to-weight ratio than in any internal combustion engine— but it creates no flame or pollution. With a loud hiss, the helicopter takes off, leaving behind a spiral plume of steam and a crowd of onlookers wondering if they have just witnessed a new wave in aviation.
