Because the engine is fixed to the airframe, this reactive torque is transmitted to the aircraft, causing a tendency to roll in the opposite direction to the propeller.
Some aircraft, such as the Sopwith Camel with its relatively heavy Clerget 9B engine, were noted for having a faster turn to one side than the other, which influenced combat tactics both with it and against it.
Handed engines have rarely been used, owing to cost, but were sometimes used for naval aircraft such as the Sea Hornet, to simplify their handling across a narrow carrier deck.
The wake of a propeller gains angular momentum, which can produce an asymmetric effect over the tail control surfaces, especially during takeoff when the engine power is at maximum but the aircraft speed is low.
For example, a single front-mounted tractor propeller may provide sufficient thrust, alongside a nose-mounted cockpit for good pilot visibility.
The Northrop Grumman B-2 Spirit stealth bomber utilizes asymmetric thrust as a means to enhance yaw control.
Both needed to be close to the centre of gravity above the front of the wing, so each was moved to one side to make room for the other.