The Solid Air Diamant Twin () is a German ultralight trike, designed and produced by Solid Air UL-Bau Franz of Hundheim, Rheinland-Pfalz. The aircraft is supplied as a complete ready-to-fly-aircraft.
The Diamant Twin was designed to comply with the Fédération Aéronautique Internationale microlight category, including the category's maximum gross weight of and, in fact, the aircraft has a maximum gross weight of . It features a cable-braced hang glider-style high-wing, weight-shift controls, a two-seats-in-side-by-side configuration open cockpit with a cockpit fairing, tricycle landing gear with wheel pants and a single engine in pusher configuration.
The aircraft fuselage is made from fibreglass, with its double surface aluminum-framed wing covered in Dacron sailcloth. Unusually the engine firewall is made from fibreglass-laminated plywood. Its span standard Bautek Pico wing is supported by a single tube-type kingpost and uses an "A" frame weight-shift control bar. The landing gear features fibreglass suspension. The powerplant is a horizontally opposed, four-cylinder, air-cooled, two-stroke, dual-ignition Hirth F-30 engine or, optionally a BMW four stroke powerplant.
The aircraft has an empty weight of and a gross weight of , giving a useful load of . With full fuel of the payload is .
A number of different wings can be fitted to the basic carriage, including the Bautek Pico and the La Mouette Ghost 12 and 14.