Abstract: An ultralight coaxial dual rotor helicopter having a substantially L shaped frame. Attached to the back of the frame is a vertical shaft engine, and a pair of yaw paddles for controlling yaw of the craft. The drive shaft connects to a belt drive at the top of the frame, which transmits the engine power to a transmission and coaxial drive gear for driving the rotors. Crank actuators are provided for tilting the rotor axis to control the pitch and roll of the craft. A pilot seat and ballast tank are attached to the front of the frame. The ballast tank may be filled with a volume of water to balance the craft for the weight of the pilot. The fuel tank is located behind the pilot seat on the centerline of the helicopter, such that as fuel is used and the weight of fuel in the tank changes, the balance of the craft will not be affected.

Abstract: A control system for a coaxial rotorcraft comprises a coaxial rotor set, further comprising an upper rotor actuated by a first drive shaft and a lower rotor actuated by a second drive shaft, the lower rotor having a direction of rotation counter to a direction of rotation of the upper rotor. A collective blade pitch control is configured to: collectively control pitch of only one of the upper rotor and the lower rotor and not another of the upper rotor and the lower rotor; and create an unbalanced torque force which acts on the rotorcraft and which enables a yaw attitude control input through said collective blade pitch control.