Drag Force Calculator Formula
Understand the math behind the drag force calculator. Each variable explained with a worked example.
Formulas Used
Drag Force (D)
drag_force = cd * 0.5 * air_density * pow(velocity, 2) * ref_areaPower Required to Overcome Drag
drag_kw = cd * 0.5 * air_density * pow(velocity, 2) * ref_area * velocity / 1000Variables
| Variable | Description | Default |
|---|---|---|
cd | Drag Coefficient (CD) | 0.03 |
air_density | Air Density (rho)(kg/m³) | 1.225 |
velocity | Velocity (V)(m/s) | 80 |
ref_area | Reference Area (S)(m²) | 25 |
How It Works
Aerodynamic Drag Force
Drag is the resistive force opposing an object moving through a fluid. It depends on the shape (captured by CD), the flight condition, and the size of the body.
Formula
D = CD × 0.5 × rho × V² × S
The power needed to sustain flight against this drag is P = D × V. Minimizing drag is a central goal in aerospace and automotive design because it directly reduces fuel burn.
Worked Example
An aircraft wing with CD = 0.03, area 25 m², flying at 80 m/s in sea-level air.
cd = 0.03air_density = 1.225velocity = 80ref_area = 25
- 01Dynamic pressure q = 0.5 × 1.225 × 80² = 3920 Pa
- 02Drag = 0.03 × 3920 × 25 = 2940 N
- 03Power = 2940 × 80 / 1000 = 235.2 kW
Ready to run the numbers?
Open Drag Force Calculator