Early Ferranti Ins System


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Feb 25, 2012
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I'm new here, but read with great interest the threads on ins systems. My
work is in electronics and embedded systems, but have an interest in historic
computing, avionics and in particular, in navigation sytems. One project involves
the Harrier FE541 ins sytems, where i've been trying to collect a set of units
to get the whole system working. Probably too ambitious a project, as so far, I
have just a platform in dubious condition and the weapons aiming computer,
which is work of art in terms of the complexity of the analog computing. Items
like the centre console map display are almost unobtainium and in any case
unaffordable as every cockpit rebuilder wants one.

Looking rounbd for a more straightforward project, I bought a Ferranti INS
system via the well known auction. From the pcb's inside, it's a early example of
a digital ins and (without disturbing the sensor block), uses mechanical
gyros for sensing. The computer uses bit slice bipolar technology and
electronic synchro to digital conversion afaics, rather than the older
servo / resolver setup. The psu block had a fried tantalum cap, which i've
replaced and from tracing out the psu input connector, looks to be 28v dc power
only. No power applied as yet though.

The aim is to get this thing working and being self contained, should be a far
easier project than Harrier project. Hendon may be able to help, but not
unless I can identify which a/c it was fitted to, The small outline suggests
limited accuracy and for helicopter, but have no idea really. Built by
Ferranti as part of GEC, around the late 70's / early 1980's.

Images Here:


Anyone in the group have any idea what this was fitted to or any other info ?.
There's no RAF stores reference number, just the type number and nato stock
code, so may not be RAF kit anyway. The "SS9" painted on the ident label (and
on the connector end of the case) may suggest something though...




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May 21, 2008
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Just saw your post. Rebuilding a Harrier FE541 INAS would be a very ambitious task indeed! If you've only got the platform and WAC then you're missing a lot of bits (Present Position Computer, Navigation Controller, Power Supply, Navigation Display Computer, Ballistics Box + a mass of complicated cabling!). Did you know that there is a complete FE541 system set up in a test rig at the Museum Of Flight, East Fortune Airfield, near Edinburgh? I don't know if it's still on display. It was the "reference system" held by Ferranti in Edinburgh as part of the support they provided to the RAF when it was in service.

I think those pictures are of the "2GINS" system (2 Gimbal Inertial Navigation System). If that's what it is then it was a small private venture initiative into low-cost INS and I don't think many were made/sold (I would guess this is the 14th C model or something like that!). I would say March 1998, based on the smaller label. The "SS9" label doesn't look like an original/official label to me.