MihsabaHow to use
The quadratic drag equation estimates resistance on a body moving relative to a fluid. Drag scales with speed squared, so required drag power rises very rapidly with speed.
- Enter fluid density.
- Enter drag coefficient and reference area.
- Enter relative speed.
- Review drag, dynamic pressure and drag power.
How it is calculated
Fd=½ρCdAv²; q=½ρv²; P=Fd·v
Example
For air at 1.225 kg/m³, Cd=0.3, area 2.2 m² and 27.78 m/s, drag force is roughly 312 N.
Important notes
The equation assumes Cd is appropriate for the actual condition. Reynolds number, orientation and geometry can change Cd and therefore the result.
Frequently asked questions
What is reference area?
It is the area used with the chosen Cd definition, often frontal area for vehicles but application-specific.
Why speed squared?
That is the quadratic drag model; doubling speed quadruples drag if other inputs stay fixed.
What is drag power?
Fd×v, the mechanical power needed to balance drag at steady speed in this model.