I need a gearset like a differential, except that I want each axle to rotate in the opposite direction. Right wheel rotate clockwise, left wheel rotate counterclockwise. Always. The device will be mounted with the axles vertical, not horizontal, so that the counter-rotation will offset rotational torque.
Does this gearset have a name? Do I have to build my own? I have looked at helicopters, but haven't found one with two counter-rotating blades, and such a gearbox as that would be ideal.
Any help/advice greatly appreciated.