The present invention is related to a compound helicopter (1) with a main rotor (13) providing lift, a pair of additional propulsion devices (14, 15) providing thrust and anti-torque and a fixed wing structure (16, 17, 26) on each side providing additional lift during horizontal cruise flight. The propulsion devices (14, 15) are arranged at each side of a fuselage body (2) with two tail booms (7, 8), one arranged at each side of said fuselage body (2), each of both tail booms (7, 8) having one of both propulsion devices (14, 15) arranged at its boom rear end (9). Each of the two tail booms (7, 8) houses an engine (21) and a drive shaft (24) driving the corresponding propulsion device (14, 15).