When viewed from the rear of the aircraft, most propellers turn in the same direction - both engines are seen spinning clockwise. Some twin- and multi-engine aircraft are fitted with counter-rotating propellers that cancel out the torque on the aircraft and make 6% to 16% more efficient than normal propellers. These counter-rotating propellers generally turn clockwise on the left engine and counterclockwise on the right wing, using two different gearboxes to achieve opposite spins.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
In which direction do aircraft propellers rotate?
On most twin- or multi-engine propeller-driven aeroplanes the propellers all turn in the same direction, so the left and the right engines rotate alike. Counter-rotating propellers, however, have the propeller(s) on one wing turning in the opposite direction to the propeller(s) on the other wing. For example, in a counter-rotating installation the propellers on the right wing turn counter-clockwise while those on the left turn clockwise. Counter-rotating installations are used on some twin- and multi-engine fixed-wing aircraft to cancel the torque that tries to roll the aeroplane in the opposite sense of the propeller rotation.
Earlier marks of the Supermarine Spitfire were equipped with the Rolls-Royce Merlin engine, whose crankshaft rotated clockwise as seen from the pilot's seat. Later Spitfire marks fitted with the Rolls-Royce Griffon engine rotated counter-clockwise. Twin-engined aircraft and watercraft often have counter-rotating engines and propellers so that one turns clockwise and the other counter-clockwise.
Do airplane propellers rotate clockwise?Early airplanes like the Sopwith Camel had clockwise rotating propellers. The Supermarine Spitfires equipped with Rolls-Royce Merlin engines rotated clockwise, as did the Merlin engine itself. Later Supermarine Spitfire versions with Rolls-Royce Griffon engines, however, rotated counter-clockwise, showing that single-engine airplanes have no performance benefits to the propeller turning one way or the other.
Counter-rotating propellers mean one turns clockwise and the other counter-clockwise. The Lockheed P-38 Lightning reversed the counter-rotation, so its right propeller turns clockwise while the left turns counter-clockwise, making the tops of the propeller arcs move outwards clockwise on the right and counter-clockwise on the left. The propeller pushes air in a twisting helix around the fuselage clockwise as seen from the cockpit, and that twisting helix pushes against the left side of the vertical tail, causing the airplane to yaw to the left. Single-engine aircraft exhibit this left-turning tendency, which pilots counter with right rudder.
