Drag Count

A drag count is a single unit of drag as defined by aerospace engineers. Drag is generally computed using the equation:

Where:

is the air density

is the current airspeed

is the drag coefficient (a dimensionless constant, usually on the order of 0.02 to 0.04 for an aircraft in cruise)

is the aircraft wing area

A drag count of 1 is equal to of 0.0001. So if, for example, the steady state drag coefficient is 0.0200 and someone sticks a hand out the window adding 5 drag counts, the new drag coefficient would be:

0.0200 + 0.0005 = 0.0205 or 205 drag counts.

Drag count is used as a crude measure for the change in drag coefficient (it is not a direct measure of drag as it is associated with a reference area, it is only valid for use as a relative assessment of change).