IIRC there was a re-engined VC10 derivative in the proposals, as well as other quite esoteric offerings.

One day the full story of how OR357 was developed (and the aircraft and engine R & D),and then over a weekend was suddenly changed to another OR thanks to extreme political machinations, will be written. Or not!

Just as an aside.Some might recall Harald Penrose , ex CTP Westlands and a well respected Aviation historian and author. Hal wrote a series of books in the 60's and 70's on the evolution of the U.K Aircraft Industry ( "British Aviation" with which Haraka Snr. had considerable involvement) . Hal decided to stop at 1939.
His reason to call a halt : "If I continue to write honestly with what I know, I fear being sued"

I was told many years ago by a person involved with a Shackleton replacement trial, that several airframes were trialed. Among them was the Vanguard, two rigid in the wings, I think the Viscount was considered too old but cannot be sure, also the Brittania and the VC10. The VC10 came out the best but they could not get enough fuel on board to give the required endurance. (Pre 73 so lots of cheap petrol). Iv'e no idea whether the engine location was an issue. No decision was made. There is a book about maritime ac development, I must dig it out and read again.

Interestingly, the Comet did not feature in the trial. I was told that during a ministerial visit to de Havilland (that may of course be Hawker Siddeley) that some spare wings were spotted, (made for a cancelled order I believe), and the suggestion for a new MPA surfaced from that visit. How true that is I have no idea.

As for the MRA4; during my time on maritime I looked with envy at the P3. Not because of it's sensors or performance, for in those areas I considered it inferior. But the fact that the seats placed you in front of the kit. You had an APU that did more than start the engines, if you were quick. An air conditioner that kept the aircraft cool on the ground with only a GPU connected and of course air stairs, simple facilities that made life so much easier. Many times we would wait for a promised GPU to turn up, and then watch a P3 land, taxi in reverse into a parking space, shut down and unload the crew and put the aircraft to bed as we waited. Fitting an usable APU to the Nimrod was considered too expensive to consider, read that as no one wanted to do it.

When the MRA4 was penned, all these facilities were included, we looked forward to a more usable ac until we lost the air stairs, too heavy. (in fact they were such a poor design they were less than useful). The APU was OK when it worked.

I still think the P8 is not the aircraft needed, there's a good reason the MAD was removed and I don't think it was because of the way the US intends to use the ac. And dropping sonobuoys from height can only be a choice made by boffins, no maritime wettie would ever consider it. Knowing where a sonobuoy is is one thing, but if its not where you intended it to be, it's just another lump of junk in the ocean.

Would the MRA4 have made the grade? I think so, although it still needed a lot of work in my opinion, but at around 15 hrs endurance it would have been quite useful. The question of build standards is way beyond my pay grade so I won't comment. Except to say I had a lot of time for the engineers, but none for the management

I can vouch for that as I was a Liney on the AEW and none of the #4 Engine Doors would close without a load of "Wiggling & Percussion Adjustment"

The doors themselves were all mixed up on them when the 11 were taken out of service for modification..

AQAfive - The Nimrod (HS801) came about purely thanks to the suddenly issued Operational Requirement (OR 381) which effectively negated all the previous work for OR 357 and was written almost completely around the Atlantique! Hawker Siddely took 7 days to come up with the 801 (Nimrod) using mainly existing Comet parts and won the contest. It was announced in 1965, first flew in 67 and front line deliveries started in 69. However, whilst it was an excellent aircraft for its time, as alluded to above it was still essentially a 1940-50 design. What might we have had had the original OR 357 winner been built. Not a P-8 certainly, but maybe we wouldn't have been in a position of needing it now either.

I beleive an assessment of the Orion was made at the time of OR.381, but range/speed etc ruled it out. There was also a Trident variant (HS800) that reached the final candidates.

There were a host of proposals based on airliners that were considered as part of the overall process leading up to that point - a Comet version was first proposed for OR350/MR218, and over the 50/early 60s Brittania and VC10 variants proposed, as well as new build aricraft designs like the Acvro 745 (which looke dlike a cross bewteen a Shackleton fuselage and an Andover wing!)

Quite a decent read on the whole process....
https://www.amazon.co.uk/Nimrods-Gen...OD%27S+GENESIS

At least we didn't get a variant of the HP 117 (it was offered!)

The Avro 776 was the Trident-based offering to rival the maritime VC-10:
http://i29.photobucket.com/albums/c2...6.png~original
http://www.bisbos.com/images_aircraf...nimrod_600.jpg

Those things look like the culmination of an incestuous relationship.

My tuppence:

For the time and money actually spent on the MR4, it'd have been better spent on coming up with a whole new airframe. Or converting an A320, or A330. If it comes to that, how expensive are used A340s to buy, operate? Ok, so that's getting quite large, but surely that means a few additional tanks can be added for very long endurance?

I've nothing against the P8 as such, it's just that it'd be nice to think that it's not just the USA who can convert an airliner into an MPA. Still, I suppose that a kitted out P8 is a single line purchase order. It should be really difficult to screw that up!

Anyone know how good the Japanese one is? Perhaps we'll find out, with military relationships with Japan seemingly blossoming at the moment.

Whose fault was MR4? Who knows. I do know that it's the hardest thing in the world to get someone to foresake their "old dependable" and replace it with something completely new, even when the old thing is obviously a pile of junk... At some point it's just not worth saving, and recognising the point optimally takes real talent.

That Trident should have won on looks alone.

I was peripherally involved in the RMPA option studies in the early 90s (before the ITT was compiled), and I remember BAe (as was) begging to be allowed to offer an all-new aeroplane, but the Treasury were adamant that they wouldn't even look it it because it was too technically risky (ironic, in hindsight). The A320/340 options were looked at, but they were deemed to be unsufficiently rugged and unlikley to stand up to the low-level rough-and-tumble that sub-hunting entails.

PDR

PDR, my memories agree. The original proposal was for a missions​ system upgrade, new more fuel efficient engines (GE) and a glass cockpit. This fitted in with the target budget and maximised the existing investment in Service infrastructure. History records what came out of the subsequent negotiations with pretty much the same price to boot. At this point a new airframe would have reduced the risk substantially but that's hindsight.

EAP

Unfortunately it always seems the Treasury puts the boot in and can only be persuaded to fund an 'upgrade' - ie Shackleton Mk 2 to Mk 3, Nimrod 2 to 4, Sea King (too various to mention)and the same with many other items across the military spectrum. So we end up with cost overruns, old equipment with (relatively) modern upgrades etc, instead of new build, more efficient and in the long run cheaper aircraft etc. And who gets the blame - MoD or the single service involved.

OTOH, whilst agreeing with what you say, UK Mil procurement has also resulted in some very expensive and prolonged development of NEW items which, unsurprisingly, failed to generate much (if any) overseas sales to amortise the R&D and production costs.

So even if the money can be squeezed out of the Treasury, it doesn't always work out very well.

There is an old adage. Never modify a mod. Not set in stone, but there to warn of inherent risks that must be mitigated before being allowed to commence development. In the mid-90s, you had to disobey direct orders to let such a risk reduction contract. That is why SKAEW was such a relative success, as it faced the same risks as Nimrod yet delivered on time, under cost and to a better spec than the FAA asked for. (And was the lead programme on some new technologies common to both). What MoD will not tolerate is using such successes as a benchmark, as it raises the bar.

P8 will provide a superb platform, that will be "S" far more than a cobbled together 1950s relic. Look at the Voyager/MRTT, they are doing a fantastic job, day in day out. Common sense says use a modern, reliable commercially successful platform to start... can you imagine trying to get a wiggle valve widget for a MR4 in any location apart from the UK?

Sorry, but I'm a Professional Engineer and it is my experience that "Common Sense" is almost invariably neither.

Show me a modern airliner that routinely flies low with aggressive manoeuvering over the open ocean in all weathers and perhaps I might accept the point had some merit. But I can't think of one off hand - I'm sure the passengers would have noticed.

PDR

I would think that a brand new, modern, multi-billion dollar computer designed airliner that has been shaken down for the last 30 years would stand a better chance of surviving in that environment than a bodged up comet? Plus the maintenance is very well understood, spare parts available off the shelf, worldwide, huge manufacturer support etc... I don't believe the comet was ever designed to be operated low level across the ocean either?

It's time we learn from our mistakes, flogging the VC10 & Tristars on for as long as we did led to serious operational performance problems, not only from a (hideous) reliability point of view, but supporting the aircraft worldwide with no real back up from the manufacturers etc.. Operating a modified civil airliner has huge benefits that vastly outweigh any downsides. Funnily enough, all of the old sweats crowing about how the A330 was vastly inferior to the old Vickers funbus & deathstars have gone very quiet.

The Operators, Engineers, Passengers, Receivers all love the MRTT, because it turns up, does its job & goes home..... There is a lesson in there somewhere?

Besides, the venerable 73' has looked after numerous lo-co sausage factory first officers, including "that" Irish Airline, I'm sure the Raf couldn't be much heavier on it!