Pitot Tube
A pitot tube (/ˈpiːtoʊ/ PEE-toh) measures fluid flow velocity. It was invented by French engineer Henri Pitot during work with aqueducts in 1732 and later adapted for modern aviation and industry. It is widely used in aircraft, boats, and industrial applications.
Theory of Operation
The pitot tube is a device for measuring fluid velocity by converting the kinetic energy in a fluid flow into potential energy. It measures the difference between stagnation pressure (measured in the pitot opening facing the flow) and static pressure.
Basic principle:
- Stagnation pressure = Static pressure + Dynamic pressure
In aviation, the difference between the stagnation and static pressure is used to compute the dynamic pressure, which in turn is used to determine airspeed.
Use in Aircraft
Aircraft use pitot tubes to measure airspeed. These are typically mounted on the wings or nose, oriented directly into the airflow. The measured pressure difference is translated into airspeed through mechanical or electronic systems.
Aircraft and Accidents
The pitot-static system (which includes the pitot tube) is vital to flight safety. Blockages or failures can lead to erroneous airspeed readings.
Notable incidents:
- Austral Líneas Aéreas Flight 2553
- Northwest Airlines Flight 6231
- Birgenair Flight 301
- Air France Flight 447
- In 2008, Air Caraïbes reported pitot tube icing issues on its A330s.
For more information, see: Pitot-static system
