The Berkshire Concept 70, sometimes called simply the C-70, is an American, single seat, high-wing, 15 metre class competition glider that was designed by Arthur Zimmermann and produced by the Berkshire Manufacturing Corporation of Lake Swannanoa, New Jersey between 1971 and 1974.
[1][2] The Concept 70 was intended to be a domestic US fiberglass sailplane that would compete with the best European 15 metre aircraft being produced in the late 1960s.
[1][2] The aircraft is made from molded fiberglass, with an internal fuselage steel frame skeleton that connects the monowheel landing gear and the wing fittings to the fuselage, while also providing a protective cockpit cage for improved impact survivability.
The flaps permit very steep approaches, allowing the aircraft to land in small fields with obstacles.
The aircraft also has retractable landing gear and was available with optional water ballast tanks with a 200 lb (91 kg) capacity.