The moment coefficient about the quarter-chord (c) is a dimensionless parameter used in aerodynamics to describe the aerodynamic moment or torque acting on an airfoil or wing about a point located a quarter of the chord length () behind the leading edge. It provides a normalized measure of the rotational force that causes the airfoil to pitch or rotate around this specific point due to aerodynamic forces.
- is the moment coefficient about the quarter-chord.
- is the moment coefficient about the leading edge.
- is the lift coefficient.