Definition
The collective set of forces produced by a turning engine and propeller that tend to yaw, roll, or pitch the airplane away from straight flight. The four primary effects are torque (the airplane's tendency to roll opposite to propeller rotation), the slipstream's spiraling action striking the vertical tail and yawing the nose, gyroscopic precession (a force applied to the spinning propeller acting 90 degrees later in the direction of rotation), and asymmetric propeller loading (P-factor), which causes the descending propeller blade to produce more thrust than the ascending blade at high angles of attack.
Plain English
A spinning engine and propeller don't just pull the airplane forward. They also try to twist it, roll it, and push the nose sideways. Pilots use rudder and aileron to keep the airplane flying straight despite these tendencies.
Context Anchor
Seen during takeoff, climb, slow flight, and any power change where the airplane may need rudder or other control input to stay coordinated.
Derivation
Propeller comes from Latin roots meaning “to drive or push forward.” That helps because the propeller’s main job is to drive the airplane forward, but while doing that it also creates side effects the pilot must control.
Why Pilots Care
These effects must be countered with rudder to keep the aircraft in coordinated flight and avoid loss of directional control on takeoff or in high-power maneuvers.
Grounding Statement
Add power at low airspeed and the airplane may immediately need correcting pressure on the controls to keep it straight.
Intuition Check
Do not think of engine/propeller effects as only “more thrust.” The engine and propeller can also create turning and twisting tendencies that affect aircraft control.
Example Sentence 1
On the takeoff roll, the student applied right rudder to counter the engine/propeller effects pulling the nose to the left.
Example Sentence 2
During a climb in coordinated flight, small rudder adjustments are used to cancel engine/propeller effects and center the inclinometer ball.