In flight mechanics, the local skin friction coefficient refers to a dimensionless parameter that quantifies the shear stress acting on the surface of an aircraft due to the friction between the air (fluid) and the surface. It is a crucial factor in the study of aerodynamics and the analysis of aircraft performance.
- Cf is the local skin friction coefficient (dimensionless).
- τw is the wall shear stress, which represents the shear stress acting at the surface of the aircraft (in pascal or pound-force per square foot).
- ρ is the air density (in kg/m³ or slugs/ft³) at the location.
- V is the local airspeed or velocity of the fluid (air) relative to the surface of the aircraft (in m/s or ft/s).