What is load factor?

• A. the ratio of aerodynamic force put on the airplane to the actual weight.
• B. the ratio of thrust to weight.
• C. the amount of weight the airplane feels in different configurations.
• D. the ratio of wing area to weight.

Answer: (A)

Load factor is the ratio of the lift the wings generate to the airplane’s weight. Lift is the aerodynamic force that supports the aircraft in the air, acting perpendicular to the flight path. In straight-and-level flight, lift equals weight, so the load factor is 1 g. When the airplane banks or maneuvers, more lift is required to both support weight and provide the necessary centripetal force for the turn, so lift increases and the load factor becomes greater than 1. This is why occupants feel heavier during turns—the airplane is experiencing a higher load factor, or higher apparent weight. For example, in a level turn with about a 60° bank, the load factor is roughly 2, meaning the lift must be about twice the aircraft’s weight.

This concept matters because it affects structural stresses and stall margins: higher load factors increase wing loading and raise the stall speed in turns. The correct description of load factor is the lift-to-weight ratio. The other ideas—thrust-to-weight, simply “weight the airplane feels,” or wing area relative to weight—do not define load factor, though they relate to other performance or loading concepts.