US Patent 9321526 Compound helicopter

The invention relates to a compound helicopter comprising a fuselage, at least one engine and a main rotor driven by said at least one engine. At least one pair of fixed wings are mounted in an essentially horizontal plane on a left hand and a right hand side of the fuselage and horizontally oriented propulsion devices are mounted to each of the fixed wings, the fixed wings encompassing each a drive shaft from the at least one engine. Each fixed wing comprises a lower main wing and an upper secondary wing being connected to each other within an interconnection region. The propulsion devices include pusher propellers arranged at the interconnection region and the upper secondary wing houses the drive shaft from the at least one engine.