From 1969 to 1976 I was a Computer Tech on the Harrier Simulator at RAF Wittering.
The system was designed and built by Link Miles later to become Singer Link i think.
The Sim had 3 models as described previously, horizontal mounted on the floor.
The large scale model filled a large part of one model room covered about 200 by 200 miles of Poland centred around the River Vistula. It was indirectly lighted with a light box system mounted on the camera gantry and was used for high-level work.
The second model contained 2 models a tactical low flying model and the airfield model, it was light by 400 x 1000watt ceiling mounted lamps. The camera gantry had a scale speed limited to about 320knts but we as systems techs could override that.
The cockpit system was mounted on a 4 axis motion system, pitch, heave roll, and sway. The whole thing weighed about 10 tons and could move up to 24 inches a second in sway. I once tested all axes from 1/64 cycles a second up to 5 cycles a second to measure the lag between the Visual / Motion and Flight systems for the IAM, as there was a lag between the 3 systems. The system was driven by a pair of massive hydraulic pumps operating at 400psi????
There were 2 generations of visual display system. The original system consisted of 3 high power projectors mounted on a gantry above and behind the cockpit illuminating a large screen mounted in front giving around 20/20 (???) Degs left / right and 15/15deg up down. Because of the massive load on the motion system this caused the 2-foot diameter roll bearing to fail several times. This system required a massive effort to set it up correctly and was also deadly as the projectors required around 25 Kvolts and lots of care was required to ensure they were fully discharged before servicing. One of out Techs Ian J (Put Put )
Was a past master at setting this all up, would take him all night!
The replacement system consisted of a large TV Screen (32’’ maybe) mounted above the cockpit wind shield area which shone onto a special lens mounted at 45 deg to reflect the picture with much smaller screens behind it. This system gave a much-improved field of view, but was a bit sensitive to heavy bumps from the motion system. Think this was called WAC Window (Wide Angle Collimated) Display
The cockpit system comprised of as much original equipment as possible and Link Miles had devised some special electronics to interface to the original gauges and display units such as the HUD and moving map
The original (before 1976) computers were Elliott 4130, which was 24, bit register digital computers.
The Harrier sim had 2, one with 16K of 24 bit core memory the other with 32K. The maximum memory was 64k. The system was programmed in NEAT (National Elliott Automatic Translator) and data entry was by high-speed 8 bit paper tape readers. With 2 Westrix teleprinters for human interface.
Between the computers was a device called the trainer and simulator transfer unit (TSTU) and 2 massive cabinets that converted the digital signals into analogue signal to talk to the simulator electronics.
Consisting of things like digital to analogue converters, DC analogue to Ac converters, syncro drivers and lots of other very cleaver things.
We all became expert jockeys but with the added advantage that we could do special things. E.g. we could freeze the fuel at 1 lb a side, or double the thrust of the Pegasus 101/3.
We were very much involved in system programming doing command mods for things like IFF, Dive brake functions and other things. We also assisted in a programming exercise with RR and LM for the 103-engine development.
For its day it was a chunk of very cleaver engineering by Link Miles and much enjoyed by the Instructors and Engineers.
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Last edited by orionsbelt; 2nd Nov 2012 at 20:29.