|Object Name:||Static Transducer Mk3|
|Year of Manufacture:||1970|
|Location:||Main Object Store|
Static Transducer Mk 3
Type No. 12-006-01
Ser. No. X004/70
Modification State -
Tag No 48
Property of MoD
EBL 638 [inspection/repair stamp]
Marconi Collection Ref: 2047
This Static Transducer unit was designed for and fitted to either the English Electric Lightning or the Blackburn Buccaneer.
The unit contains the pressure transducer which converts the Static pressure, from the aircraft sensor, to an electrical analogue. The static pressure system is open to the exterior of the aircraft to sense the pressure of the atmosphere at the altitude at which the aircraft is flying.
The difference between the Pitot pressure and the static pressure is called dynamic pressure. The greater the dynamic pressure, the higher the airspeed. So the Static Transducer working with the Pitot unit has the capability to provide an output of indicated airspeed, limits on the altitude and also to manage the maintenance of a specific altitude ; the height lock function. The Pitot and Static transducers will drive a cockpit instrument for indicated airspeed but will also feed into the Autopilot and automatically control the flying surfaces to maintain a pre-set speed or altitude.
The Differential Pressure Transducer within the box contains two aneroid capsules, or diaphragms, which expands and contracts with the pressure input from the Pitot tube. The case around the diaphragm is airtight and is vented to the static port. The use of multiple aneroid capsules is to multiply the movement. The movement of the diaphragm is mechanically coupled to a non-linear cam assembly with two rows of fifteen adjustable grub screws to set the desired profile. Within the casing is a wire wound resistor which is driven by the cam mechanism such that an electrical output of indicated airspeed is provided corrected by the cam profile for the non-linearity of the diaphragm movement. A small servo motor was used to amplify the movement of the capsules to operate the internal gear train.
This Static Transducer unit has been given an X Serial number indicating that it is an experimental or development unit. It was made in 1970 and is a Mk3 design. The Mk2 Type D was fitted to the Lightning so this may be a development for a later version of the aircraft. The relationship between ‘Type’ and ‘Mk’ numbers is not known but it would seem that ‘Type’ (in this case no ‘Type’ is given) can have incremental ‘Mk’ numbers; this being a ‘Mk3’.