Cool article on Wired.com..
Maddox has been into skydiving for 20 year and used to compete in tracking contests, where free-falling skydivers move horizontally across the sky at speeds approaching 120 mph. His buddy was always just a little bit faster, so Maddox thought “it’d be fun to strap a jet engine to my chest and make myself into a human missile.”
He discovered turbine jet engines are expensive. But pulse jets are as cheap as they are simple, so Maddox set to work building one. “All I started with was a schematic out of an encyclopedia,” he says. The engines are basically a long tube with a fuel pump, a spark plug and a reed valve. Air and fuel are mixed at the front and ignited in a process that repeats - or “pulses” - about 70 times a second.
Maddox soon had a working engine and he developed a throttle that allowed him to control the level of thrust - something he says is rare on a pulse jet. He made three jumps from a plane (that’s him in the pic) but quit because “the fuel system was a little scary” and he worried about setting the plane on fire. But Maddox was hooked.
