Pitot Tube Velocity Calculator Formula
Understand the math behind the pitot tube velocity calculator. Each variable explained with a worked example.
Formulas Used
Flow Velocity
velocity = sqrt(2 * (total_pressure - static_pressure) / density)Dynamic Pressure
dynamic_pressure = total_pressure - static_pressureVariables
| Variable | Description | Default |
|---|---|---|
total_pressure | Total (Stagnation) Pressure(Pa) | 102000 |
static_pressure | Static Pressure(Pa) | 101325 |
density | Fluid Density(kg/m3) | 1.225 |
How It Works
Pitot Tube
A pitot tube measures airspeed by comparing stagnation (total) and static pressure.
Formula
v = sqrt(2 (P_total - P_static) / rho)
where the difference (P_total - P_static) is the dynamic pressure q = 0.5 rho v^2.
Pitot tubes are standard instruments on aircraft for measuring airspeed.
Worked Example
Aircraft: P_total = 102 000 Pa, P_static = 101 325 Pa, rho = 1.225 kg/m3.
- 01dP = 102000 - 101325 = 675 Pa
- 02v = sqrt(2 * 675 / 1.225)
- 03v = sqrt(1102)
- 04v = 33.2 m/s = 119.5 km/h
Frequently Asked Questions
What is stagnation pressure?
It is the pressure at a point where the flow is brought to rest (stagnated). It equals static pressure plus dynamic pressure.
How does a pitot-static system work on an aircraft?
The pitot port faces forward to capture total pressure. Static ports on the fuselage measure ambient pressure. The difference gives dynamic pressure and hence airspeed.
Does this work for supersonic flow?
For supersonic flow, a bow shock forms ahead of the pitot tube. A modified (Rayleigh) equation accounting for the shock must be used.
Ready to run the numbers?
Open Pitot Tube Velocity Calculator