In the mid-1960s, engine manufacturer Williams Research developed a light turbofan engine, the “WR19”, with a thrust of 1.91 kN (195 kgp / 430 lbf), which was used in a “flying belt” that could be strapped on somebody’s back to allow flights of up to 20 minutes. It was a sexy toy but of no particular usefulness, and it was canceled in 1969.

Williams continued to tinker with the idea, coming up with a one-man flying platform powered by the WR19 or a derivative engine, known as the “WASP”, which was later renamed the “X-Jet”. This machine looked something like a flying trashcan on skids, and could carry a pilot directing the machine with two grip-type controls. It was evaluated in the 1980s; videos of its flight suggest it performed very nicely and was easy to handle. Noises were made about a more capable successor, but apparently its endurance was too limited and, as was the case with most of the other one-person flying machines, it was hard to understand that it offered any utility proportional to its expense and complexity.

One X-Jet is now on display at the USAF Museum in Ohio, while another is on display at the Seattle Museum of Flight. The WR19 and its descendants did prove to be useful powerplants for long-range cruise missiles.