The invention concerns a small-size radio-controlled flying device propelled by a heat engine (20) with pusher propeller (10) for remote sensing, said device enabling short take-off and landing and a maximum flying speed of 34 Km/h. The device comprises a nacelle and a wing system, the nacelle (1) being a rigid three-wheeled carriage capable of being disassembled by denesting a more or less pyramidal jig with rear base (2) and front top (7), a lower plane (3) two lateral planes (4, 5) and an upper plane (6), the base being a single-piece welded element and comprising the engine, the propeller, a tank and the remote sensing unit, the top being a single-piece welded element, the lower plane and the two lateral planes comprising side members (11, 12) at least assembled at the base and at the top, the lower plane comprising at its three end angles two rear wheels (8) and a front wheel (9), the front wheel being arranged overlapping forward in the top and the wheels being low pressure tyres, the wing system (13) being a wing box flexible parafoil, said wing system being linked to the nacelle adjustable by two front suspension cables (17), two braking suspension cables (18) acting on the two flaps/wings.