Patent attributes
A first propeller has a shorter blade length and a lower inertia than a second propeller. An electromagnetic field emitter is coupled to one of the first propeller or the second propeller and an electromagnetic field receptor is coupled to the other one that is not coupled to the electromagnetic field emitter. The electromagnetic field emitter emits an electromagnetic field. In response to the electromagnetic field: the electromagnetic field receptor and its coupled propeller rotate in a first rotational direction; and the electromagnetic field emitter and its coupled propeller rotate in a second and counter-rotational direction. In response to a second electromagnetic field associated with increasing torque: the first propeller increases and subsequently decreases its rotational speed; and the second propeller increases its rotational speed at a slower rate than the increase in the rotational speed of the first propeller.