AI.25 hypothetical musings

[zen]

It struck pondering what I now know about UK AI radar efforts...
Whether like the AI.21 and AI.23, there was a similar parallel in AI.24 and AI.25...?

Consider the following.

AI radars, in 1963 - 1966 timeline:

Hughes/EMI Pulse-Doppler radar for P.1154 (800lb weight)
Ferranti OSIRIS Pulse-Doppler radar for the P.1154
Elliott coherent radar proposal for Lightning
GEC incoherent MTI module for AI Mk 18 adaptable to AI Mk 23
Ferranti / Hughes coherent MTI module for AI Mk 23 (based on CORDS for the AN/APQ-109)

From Tony Wilson, English Electric Lightning - Genesis & Projects

AI.24 was always an ambitious system that originally was FMCW. The back-up option on this all new system and technology was interruption of the signal. Hence FMICW instead.

But had GEC abandoned all effort on the AI.18?
No.
Lots of effort was still being put into new technologies on this set after 1957. After the F.155 J-Band development was canned.
Improvements in performance were trialled with good results but not bought.
AMTI was trialled for look-down shoot-down captain. But not bought.
Essentially the back end 'core' of the system was by then dated...

And so it struck me, did GEC maybe go a step further than just priced up improved AI.18 options and apply modern technology of the time to a AI.18 successor?
Not a radical solution like FMICW, but just a solid transistorised successor to AI.18 in the long desired J-band with all the improvements applied from the get go....
Could this be AI.25?

 

[yellowaster]

I wonder whether there was ever a 'hard' attribution of AI mark number to the various proposed but unbuilt UK radars. E.g. There was a radar proposed for the OR.329. Then there was the circa 1960 Admiralty requirement for an improved AI (non-coherent with lots of improvements) for the Sea Vixen in mid-1960s. And then there was the coherent AI planned for the P1154B. There may have been others judging by list above. I'd guess the way it would work would be that the first of these projects to get fully-approved for development/production would take the 'AI Mk 24' designation (and get an ARI number); the next 'AI Mk 25' and so on. My suspicion is that any references to AI Mk 24 and AI Mk 25 when talking about proposed/unbuilt radars is completely unofficial - just a bit of shorthand for 'the new radar'. To support my view, none of the documents I've seen talking about the FMCW/FMICW radar ever mention an AI mark number. However I stand ready to be corrected.

 

[overscan (PaulMM)]

I agree with that. "AI Mk 24" in Ministry minutes is shorthand for "new radar that if put into production would be AI Mk 24". E.g -

AI Mk 24 - F155T stage 1 AI-18 development
AI Mk 25 - F155T stage 2 Pulse-Doppler radar

 

[yellowaster]

Right. Unfortunately of course, it does make discussing proposed radars more difficult, since you now have to talk about, for example, the 'developed non-coherent radar proposed in 1960 for the Sea Vixen, for service in 1966' , rather than just 'AI Mk 25'.

 

[zen]

That said we have the example of AI.21 and AI.23.
Both to the same requirements I vaguely reccal.
Both certainly for the same aircraft.

One a riskier but higher performance system from Ferranti.
The other a less risky and lower performance system from EKCO.

However the obvious way past this AI.X issue is to give each option a name.

Such as we have the Aspinal radar....

 

[overscan (PaulMM)]

Ekco's AI Mk 20 was ordered as a backup / interim option for Ferranti's more ambitious AI 23. They weren't "rival" systems.

 

[yellowaster]

Yes. AI Mk 20 was actually ordered (and then cancelled). Similarly, contracts were issued for AI Mk 16, although it was later superseded. The outlier is AI Mk 19 (X-band AI Mk 17) which only ever existed in experimental form, yet managed to get a mark number (although I think Ekco may have got some sort of contract for it).

 

[zen]

Ekco's AI Mk 20 was ordered as a backup / interim option for Ferranti's more ambitious AI 23. They weren't "rival" systems.

True but they were concurrent efforts to meet the same need and one was a safer more reliable means to a system, the other more risky but worth it, if it succeeded.

 

[yellowaster]

Ekco's AI Mk 20 was ordered as a backup / interim option for Ferranti's more ambitious AI 23. They weren't "rival" systems.

True but they were concurrent efforts to meet the same need and one was a safer more reliable means to a system, the other more risky but worth it, if it succeeded.

Yes - my reading suggests AI Mk 20 was intended for Lightning, but was superseded by superior AI Mk 23, then relegated to interim radar. RRE/RAE thought that pilot of a single-seat fighter could only handle a very simple radar - hence simplicity of AI Mk 20 - Ferranti proved them wrong.

 

[Archibald]

Unfortunately for the Crusader III, the USN didn't followed the move (just kidding ! 100% different requirements)