A helicopter has a propulsion system that includes a diesel engine driven electric generator, battery storage, power inverters for converting AC current to DC current and converting DC current to AC current, and an electric motor powered main rotor and an electric motor powered tail rotor. The propulsion system is integrated with electric controls of the main rotor electric motor and the tail rotor electric motor to provide additional system efficiencies. The design of the helicopter allows a single engine helicopter to be just as safe as a twin engine design helicopter while consuming less fuel. The helicopter design also includes a main rotor tilt system which tilts the rotation axis of the main rotor forward during high-speed flight to improve the aerodynamic efficiency of the helicopter airframe and rotary wing.