Airplane Speed Sensor

Fregis Effayong Rowan

UniversityMechatronic

How do they look like?

Pitot tube Invented by a French Engineer (Henry Pitot) in 1732 A pitot is a pressure measurement instrument used to measure fluid flow

velocity. Pitot was modified to it modern way form by another French scientist called

Henry Darcy later in the mid 19th century. The air speed indicator measures the difference between a static sensor not

in the air stream and a sensor (pitot tube) in the air stream. When the airplane is standing still, the pressure in each tube is equal and

the air speed indicator shows zero. The rush of air in flight causes a pressure differential between the static

tube and the pitot tube. The pressure differential makes the pointer on the air speed indicator move.

An increase in forward speed raises the pressure at the end of the pitot tube.

In airplanes, electronics also compensate for altitude and air temperature to make the air speed measurement accurate.

How aircraft speed sensors work?

Stagnation pressure = static pressure + dynamic pressure

NOTE: That equation applies ONLY to fluids that can be treated as incompressible. Liquids are treated as incompressible under almost all conditions. Gases under certain conditions can be approximated as incompressible.

The laser light velocity sensors have been successfully tested in a high-speed wind tunnel

• Some Engineers from University of New South Wales (UNSW) have developed a low-cost laser that can accurately and speedily measure the velocity of commercial aircraft. Instead of having physical components located in the airflow, the new laser light system can be located in a temperature-controlled environment inside the plane, which will hopefully reduce the number of plane crashes.

• The currently used velocity sensors, known as Pitot tubes, are susceptible to icing over in bad weather and have been suggested as possible failure points for several fatal aircraft accidents.

• The most notable of these was Air France Flight 447, which crashed into the Atlantic Ocean in 2009; 216 passengers and 12 crew members died.

Conclusion

• Since the accident, Air France has replaced the pitots on its Airbus fleet with a newer model.

• http://www.youtube.com/watch?v=JRnRKJRSI4I