Both designs used the principle of counter-rotating side-by-side intermeshing rotors, as the means to solve the problem of torque compensation, normally countered in single–rotor helicopters by a tail rotor, fenestron, NOTAR, or vented blower exhaust.
The two designs employed the concept of rotating blades that mesh together in opposite directions, serving as a solution to counteract the problem of torque, which is usually mitigated in single-rotor helicopters with the aid of a tail rotor, fenestron, NOTAR, or vented exhaust.