Uninstalled Drag Coefficient (): is a dimensionless coefficient that characterizes the aerodynamic drag of an aircraft in its clean or baseline configuration, meaning it has no external attachments, such as external fuel tanks, bombs, or other stores. It represents the resistance force generated by the aircraft’s airframe, including the fuselage, wings, tail, and other components, when it is flying without any added external items.
- is the uninstalled drag coefficient.
- represents the mass of the external stores (typically in kilograms or pounds).
- is the partial derivative of the total drag coefficient () with respect to the mass () of the external stores. It essentially measures how the total drag changes as the mass of external stores varies.