What is the term for the effect of the downward descending blade producing more thrust than the ascending blade?

The correct choice is related to the phenomenon of asymmetric thrust produced by a rotor system during flight, specifically in helicopters or variable-pitch propellers. The term "P Factors" refers to the difference in lift generated by the ascending and descending blades of a rotor system.

In a rotating system, as the blades move through the air, the blade that is descending (moving into the relative wind) generates more lift and thus more thrust compared to the ascending blade (moving away from the relative wind). This occurs due to the varying angle of attack experienced by the blades as they rotate. When the blades rotate, one blade has a higher speed through the air than the other, leading to a difference in aerodynamic forces acting on each blade.

Understanding P Factors is crucial for pilots as this effect can lead to unbalanced flight characteristics, particularly in single-rotor helicopters, which can result in yaw motion when the aircraft is producing significant power during takeoff or climbing. This knowledge assists in effective control and maneuvering of the aircraft and helps design the pilot's response to the conditions of flight.