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Author Topic: Anything at all on AI Mk. 25  (Read 3433 times)

Offline Maury Markowitz

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Anything at all on AI Mk. 25
« on: October 16, 2014, 08:00:14 am »
I've come across a few fleeting references to AI Mk. 25, supposedly for Hawker Siddeley P.1154. But now I can't find anything.

The naming is curious. It suggests that it was designed after Mk. 24, which seems highly unlikely! Or maybe they skipped a few numbers?

Does anyone else have anything on this, or perhaps better google-fu?

Offline JFC Fuller

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Offline Maury Markowitz

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Re: Anything at all on AI Mk. 25
« Reply #2 on: October 28, 2014, 08:12:16 am »
Yes, but nothing very specific in that thread. The same mentions and hints...

Offline PaulMM (Overscan)

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Re: Anything at all on AI Mk. 25
« Reply #3 on: October 28, 2014, 09:31:30 am »
I've come across a few fleeting references to AI Mk. 25, supposedly for Hawker Siddeley P.1154. But now I can't find anything.

The naming is curious. It suggests that it was designed after Mk. 24, which seems highly unlikely! Or maybe they skipped a few numbers?

Does anyone else have anything on this, or perhaps better google-fu?


I have seen references to "AI Mk 24" in the mid/late 50s in connection with other planned radars after AI Mk 23. There was the Aspinall CW radar, AI 18 derivatives, J Band AI 23 and other designs planned at that time. Its likely that this AI Mk 24 has little to no connection to Foxhunter. It just means "the radar after AI Mk 23", with AI Mk 25 being the radar after that.
« Last Edit: October 28, 2014, 10:13:35 am by PaulMM (Overscan) »
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Offline PaulMM (Overscan)

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Re: Anything at all on AI Mk. 25
« Reply #4 on: October 28, 2014, 10:11:50 am »
Incidentally, I believe the "Aspinall CW radar" was a Radar Research Establishment design by Rueben Aspinall, CBE. He was a key figure in the development of coherent radar in the UK.

http://www.purbeckradar.org.uk/penleyradararchives/documents/aspinall/letters/index.htm

Quote
These letters contain lists of the extensive information Mr Aspinall had on his post-war work on Guided Weapons. This was all passed to CHiDE for safekeeping and will be available there.

Obtain docs on CD here: http://www.purbeckradar.org.uk/penleyradararchives/request/


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Offline PaulMM (Overscan)

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Re: Anything at all on AI Mk. 25
« Reply #5 on: October 28, 2014, 10:16:08 am »
CHiDE was this - http://histru.bournemouth.ac.uk/CHiDE/CHiDE.htm - apparently the archive was transferred to the Imperial War Museum, so any papers from Aspinall should now be there.
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Offline JFC Fuller

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Re: Anything at all on AI Mk. 25
« Reply #6 on: October 30, 2014, 10:02:35 am »
Maury,

The point I was trying to make is this. The only reference I have ever found to an AI.Mk.25 is in relation to a possible Sea Vixen upgrade around the time P.1154 was cancelled. This reference is vague at best and may even be a typo or just a hypothetical designation with no actual radar associated with it.

Offline JFC Fuller

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Re: Anything at all on AI Mk. 25
« Reply #7 on: November 08, 2014, 02:03:32 pm »
I had a dig around in the National Archives on this topic today. I was unable to relocate the original AI.25 reference but what was apparent was that very little real AI radar work was between the early 60s and about 1970.

Virtually nothing was done on the radar for the P.1145RN prior to its cancellation aside from the most simple requirements definition.

The UK seems to have had virtually no interest in an AFVG interceptor though a study was undertaken to see if air-air missions could be done with the radar used for the strike version, the results were not great, though it was compared against a hypothetical FM/ICW type in a full interceptor configuration. The amusing thing is a comment made in 1970 pointing out that the French AFVG interceptor radar requirement had been nearly identical to the then UK MRCA AI radar requirement.

GEC seems to have done some, at least theoretical, work on an improved AI.18 circa 1959 though its unclear whether any of this was rolled back into AI.18. It was made clear as early as 1959 that the RN wanted its new interceptor to have an entirely new radar.     

Offline zen

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Re: Anything at all on AI Mk. 25
« Reply #8 on: December 03, 2016, 09:38:13 am »
So first point is that there was work post '57 on new radars leading to a system that was intended first for the Or.346 aircraft, this being as FMCW system, but trials where disappointing. Treasurey approval in Oct '57 for a proof of concept 200W search only FMCW AI set aiming fora range of 50nm.

However the backup option was to move to PD and this option was ultimately put into action at the end '62 as a FMICW system. Flights proved the concept, such that this was the basis in '62 for the new X-band AI set for the P1154B, aiming for a 60nm range against a Canberra sized target with an auxillary Q-band using the same dish for use in ECM conditions.
By '64 this program was on good shape, but when the Admiralty abandoned the P1154B in the later part of the year, the program was downgraded to a research project looking at future AI and AEW technologies.
During '65 the AFVG lent new impetus to the effort but now Elliot was leading rather than G.E.C. constraints meant the X-band only system could be fitted into a trials Canberra as the indended use of a Valient for the full set suffered from the grounding of the Valient fleet. Flight trials began in Sept '66. The porgam suffered from a rationalising act in '66 as there was no need for a UK developed AI set, and so the flying was stopped in '67.

The ADV concept of the MRCA (Tornado) was on the cards from '69, and definition of the AI set for it was during '69 as a AI set using X-band FMICW of 1.5 -2kW. In 1970  the verdict was that it was not only possible but desirable to pursue a UK based solution and by '71 the earlier Elliot set was flying again in support of the effort.
Proposals by MEASL and Ferranti in '72 both being X-and 2kW FMICW with high PRF.

So I think we can answer that, AI.24 was always the designation of the new generation AI set after AI.18, but AI.25 might (and I stress might here) be an option for scaling the system down to fit the Sea Vixen's nose as the orriginal OR.346 to P1154B effort was a 36" dish and 32" sub-reflector.