The Fly Air Trike Moster is a Bulgarian ultralight trike that was designed and produced by Fly Air Limited of Trudovec. The design is supplied complete and ready-to-fly.
The Trike Moster was designed to comply with the Fédération Aéronautique Internationale microlight category, the German 120 kg class and the US FAR 103 Ultralight Vehicles rules. The design has a standard empty weight of .
The aircraft design features a cable-braced hang glider-style high-wing, weight-shift controls, a single-seat open cockpit without a cockpit fairing, tricycle landing gear and a single engine in pusher configuration.
The aircraft is made from square steel tubing, with its single or double surface wing covered in Dacron sailcloth. The wing is supported by a single tube-type kingpost and uses an "A" frame weight-shift control bar. The powerplant is a single-cylinder, air-cooled, two-stroke, single-ignition Vittorazi Moster 185 engine, although other engines can also be fitted.
The aircraft has an empty weight of without the wing and a gross weight of . The airframe was designed to be folded up and ground transported in the trunk of an automobile, with the wing carried on the roof.
A number of different wings can be fitted to the basic carriage as it was designed to accept most standard hang gliding wings.