A hang-gliding fanatic, Dr H Long, gave Don Mitchell control of a high performance wing. By 1975 this same wing had become the B-10. The first powered version now carries the designation of B40F (F for foot launch).
The aircraft is in effect a wing, supporting beneath its lower surface a rigid frame formed by two sets of struts in the shape of an N, at the back of which is mounted a McCulloch Mc101 12hp engine with direct drive to a two-blade pusher propeller.
The addition of a go-kart engine and streamlined pilot pod has turned the design into a high-performance ultralight. It is fast, sensitive and very maneuverable. The wing is wooden and built up in a typical “D” Section cantilever, with pilot cage attached underneath and a pusher prop in the rear. Top speed is about 55 mph, and climbout is around 350 fpm. It can be foot-launched, but the added weight of an engine and its ac-cessories make it wise to consider tricycle gear. A Mac 101 engine swings a 42-inch prop and sips two gallons of gas in two hours.