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Typhoon Air Data Pitot, Static & Flow Angle Vane

Technical Information

Catalogue No: C0973
Category: Air Data
Object Type: Sensor/Transducer
Object Name: Typhoon Air Data Pitot, Static & Flow Angle Vane
Part No: None
Serial No: 122
Manufacturer: Sextant Avionique
Division: Unknown
Platform(s): Typhoon (Eurofighter/EFA)
Year of Manufacture: circa 2000
Dimensions: Width (mm): 195
Height (mm): 35
Depth (mm): 125
Weight (g): 245
Location: Rack RAA10 [Main Store]

Sextant Avionique
S/N 122


This is an Air Data Transducer Vane fitted to the Eurofighter Typhoon. The Air Data Transducer, in con┬Čjunction with the Flight Control Computer (FCC). forms a distributed air data system for the EF2000 aircraft. Designed to measure ma┬Čnoeuvrability. it also provides data for the computation of airspeed and altitude.
The unit combines a mobile multi-function vane sensing pitot pressure, static pressure and local flow angle with a processing unit that transmits data to the flight control system. The Vane element was provided by Thales, but we built the processing element (ADT - General Assembly) prior to the divestment to meggitt as statedIt was manufactured by Thales France but after transfer of the Air Data business from Marconi Avionics it was supplied by Meggitt Avionics. The Part Number is not marked but reference to on-line maintenance data suggests it might be 13-011-01/02/05/10

Air data systems provide accurate information on quantities such as pressure altitude, vertical speed, calibrated airspeed, true airspeed, Mach number, static air temperature and air density ratio. This information is essential for the pilot to fly the aircraft safely and is also required by a number of key avionic subsystems which enable the pilot to carry out the mission. It is thus one of the key avionic systems in its own right and forms part of the essential core of avionic sub systems required in all modern aircraft, civil or military.

The air data quantities; pressure, altitude, vertical speed, calibrated airspeed, true airspeed, Mach number etc. are derived from three basic measurements by sensors connected to probes which measure:

Total (or Pitot) pressure
Static pressure
Total (or indicated) air temperature

The total pressure, PT, is measured by means of an absolute pressure sensor (or transducer) connected to a Pitot tube facing the moving airstream. The Pitot pressure is a measure of ram air pressure (the air pressure created by vehicle motion or the air ramming into the tube). When airspeed increases, the ram air pressure is increased, which can be translated by the airspeed indicator.

The static pressure of the free airstream, PS, is measured by an absolute pressure transducer connected to a suitable orifice located where the surface pressure is nearly the same as the pressure of the surrounding atmosphere. The static pressure is obtained through a static port which most often is a flush-mounted hole on the fuselage of an aircraft located where it can access the air flow in a relatively undisturbed area. Some aircraft may have a single static port, while others may have more than one. When the aircraft climbs, static pressure will decrease.

High performance military aircraft generally have a combined Pitot/static probe which extends out in front of the aircraft so as to be as far away as practicable from aerodynamic interference effects and shock waves generated by the aircraft structure. A Pitot-static tube effectively integrates the static ports into the Pitot probe. It incorporates a second coaxial tube (or tubes) with pressure sampling holes on the sides of the probe, outside the direct airflow, to measure the static pressure. Some civil transport aircraft have Pitot probes with separate static pressure orifices located in the fuselage generally somewhere between the nose and the wing.

From the measurements of static pressure PT and total pressure PS it is possible to derive the Pressure Altitude, Vertical Speed, Calibrated Airspeed and Mach number. Measurement of the air temperature is made by means of a temperature sensor installed in a probe in the airstream and from this a function called Total Air Temperature can be calculated.

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