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Triplex Transducer Unit

Technical Information

Catalogue No: C1301
Category: Air Data
Object Type: Sensor/Transducer
Object Name: Triplex Transducer Unit
Part No: 50-061-02
Serial No: 0021
Manufacturer: Marconi Avionics
Division: Instrument Systems [ISD]
Platform(s): Tornado
Year of Manufacture: circa 1975
Dimensions: Width (mm): 94
Height (mm): 170
Depth (mm): 397
Weight (g): 5,820
Location: Rack RAA10 [Main Store]

Marconi Avionics Limited
Triplex Transducer Unit
Part 50-061-02
Ser 0021
Code K0656


The Triplex Transducer Unit (TTU) was fitted to the Tornado IDS and ADV and is part of the Command Stability Augmentation System (CSAS). The CSAS system comprises an electrical link from the pilot's controls to the taileron, rudder and spoiler controls. This link is modified by computers to give good handling qualities at all times (“fly-by-wire”). Mechanical reversion exists for the taileron controls only. Control is by means of triple sensing and computing of which the TTU provides "fail safe’ air data information derived from processing of the input from three pairs of independent Pitot and Static ports. The TTU has a robust, modular construction with three air data capsules and unique processing channels.
(The system, is produced by Marconi Avionics Instrument Systems Division, Combat Aircraft Controls Division, Rochester.)
This unit has ISD inspection seals.

The primary flight controls of the Tornado are a fly-by-wire hybrid, consisting of an analogue  Command and Stability Augmentation System (CSAS) connected to a digital Autopilot & Flight Director System (AFDS); in addition a level of mechanical reversion capacity was retained to safeguard against potential failure. To enhance pilot awareness, artificial feel was built into the flight controls, such as the centrally located stick; because of the Tornado's variable wings enabling the aircraft to drastically alter its flight envelope, the artificial responses adjust automatically to wing profile changes and other changes to flight attitude. As a large variety of munitions and stores can be outfitted, the resulting changes to the aircraft's flight dynamics are routinely compensated for by the flight stability system.

The Command Stability Augmentation System (CSAS) is by its very nature one of the most complex systems on Tornado. Hardly detectable in the cockpit, the CSAS keeps the ride comfortable at all speeds and altitudes, and makes the aircraft controllable throughout the flight envelope. It is a "fly-by-wire" system with autostabilisation, the pilot’s control demands being signalled and augmented electrically to maintain good handling qualities over the wide flight envelope. In the pitch axis, the "fly-by-wire" system has mechanical reversion.

The system is triplicated and includes triplex computing, triplex rate gyros, triplex position sensors and a triplex accelerometer, with quadruplex outputs driving quadruplex electrohydraulic actuators. These "fly-by-wire" actuators were originally designed by Marconi-Elliott Avionic Systems Limited and have now been integrated by Fairey Hydraulic into the aircraft’s main hydraulic power control units.

The CSAS electronics is packaged in two units, the pitch computing circuitry being housed in a single computer and the roll, yaw and spoiler circuitry in a similar computer.

The system uses very high-precision analogue circuitry to provide accurately- matched control lanes, and a unique voter monitor design which reduces transient effects, due to system failures, to a low level and is so designed also that nuisance warnings are rare.

Marconi-Elliott Avionic Systems Limited has design leadership on the CSAS programme, but shared the production with Bodenseewerk Geratetechnik.

The system was designed to Specification SP-P-41600.

The Command Stability Augmentation System comprises the following line replaceable units,

1 Rudder pedal position transmitter              Between front rudder pedals.
2 CSAS Power Distribution Unit                     Right hand forward avionic compartment.
3 CSAS Control Unit                                       Front Cockpit - left hand console.
4 Pitch Computer                                           Right hand rear avionic compartment.
5 Lateral Computer                                        Right hand rear avionic compartment.
6 Roll Position Transmitter                             Zone 19. Roll crate.
7 Pitch Position Transmitter                           Zone 19. Pitch crate.
8 Yaw Rate Gyro                                            Zone 22. Right hand under-carriage bay.
9 Roll Rate Gyro                                            Zone 21. Left hand under-carriage bay.
10 Pitch Rate Gyro                                        Zone 21. Left hand under-carriage bay.


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