Flight efficiency improving system for compound helicopter

A flight efficiency improving system for a compound helicopter comprising a rotor and fixed wings,

• wherein while in forward flight of the compound helicopter, the flight efficiency improving system is configured to switch between not perform a cyclic pitch control of the rotor to allow a difference in lift generated by the rotor between an advancing side and a retreating side of the rotor, and to perform the cyclic pitch control to an extent that does not completely eliminate the difference, and
• wherein the fixed wings are provided respectively on left and right sides of a body and are configured to be asymmetric to each other to reduce influence of an aerodynamic interference between the rotor and the fixed wings,
• wherein the fixed wings on the left and right sides of the body are opposed to each other with the body interposed therebetween,
• wherein the fixed wings on the left and right sides of the body are different from each other in at least one of length in a direction of wingspan, and length of a wing chord, the fixed wings being configured such that a rolling moment due to lift generated by the fixed wings on the left and right sides cancels out a rolling moment due to the lift generated by the rotor on the advancing side and the retreating side, and
• wherein the compound helicopter is without a tail rotor.