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PMD Film Transport Assembly

Technical Information

Catalogue No: C1095
Category: Navigation/Inertial
Object Type: Module/Sub-Assembly/Component
Object Name: PMD Film Transport Assembly
Part No: None
Serial No: None
Manufacturer: Elliott Bros (London) Ltd
Division: Inertial Navigation [IND]
Platform(s): Jaguar
Year of Manufacture: circa 1970
Dimensions: Width (mm): 160
Height (mm): 160
Depth (mm): 135
Weight (g): 2,545
Location: Rack RAA08 [Main Store]

Various elements of this assembly have these inked ID marks:
"Drg No 75D 22540
"DL Iss 12
"Ser No. 5099"
"Drg No 75D 22330
"D.L. Iss No 13
"Ser No. 5099"
"Drg No 75D 22230
"DL. Iss No 10
"Ser No 5099"


This is the film transport mechanism for the Elliott Projected Map Display. It has sprocket wheels that engage with the perforations in the side of the film plus the associated pay-out and take-up spool shafts.

This film carriage can move to displace the film side-to-side according the the aircraft's track and the whole carriage can rotate according to the aircraft's heading. Electrical connection to the various drive motors and sensors connect via the stack of gold plated slip-rings on the insulated sleeve.

This Projected Map system predates the modern digital systems and uses 35mm film as the data store. The film is stored on spools mounted in a moveable carriage. A tungsten halogen lamp provides the light source to project the map image via an optical system on to a ground glass screen. A fresnel lens covering the screen gives even illumination and intensifies the image in the pilot’s field of view. The film strip is driven between the two spools at a rate proportional to the Easterly ground speed while the carriage holding the spools is driven in a perpendicular direction proportional to the Northerly ground speed. The map can be presented as North or Track oriented. The screen can be rotated and has a track arrow. The aircraft’s present position, track and track to the next waypoint can be presented. A film can cover an area of about 750 by 750 nautical miles with a Scale change for 1:250 000 or 1: 500 000. The PMD was used in the Jaguar Navigation and Weapon Aiming Sub-System NAVWASS. The Marconi Avionics system was replaced with TIALD from 1995

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