Related Resources: fluid flow

Aerodynamic Drag Equation and Calculator

Fluids Engineering and Design

Aerodynamic Drag equation and calculator

Aerodynamic Drag is the opposing fluid drag force that acts on any moving solid body in the direction of the fluid flow.

Symbols used:
C_d= drag coefficient
A_f = frontal area (approx. 0.9 m²)
p = air density (~ 1.2 kg m^-3)
v = velocity (ms^-1)

Aerodynamic drag force equation:

F_a = C_d A_f p (v² / 2)

Aerodynamic Calculator

Total force F_t, = F_r + F_s + F_a

Where:

F_r = Rolling resistance force
F_s = Gradient force
F_a = Aerodynamic drag force

Typical values of drag coefficient

Description	Cd
Sports car, sloping rear	0.2-0.3
Saloon, stepped rear	0.4-0.5
Convertible, open top	0.6-0.7
Bus	0.6-0.8
Truck	0.8-1.0
Motorcycle and rider	1.8
Flat plate normal to flow	1.2
Sphere	0.47
Long stream-lined body	0.1