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BAE SYSTEMS Nimrod MRA.4

Hobbes

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Rhinocrates

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One story I heard about the reasons for the cost overruns was that BAE Systems was very proud of their advanced production methods ensuring precision and uniformity of parts... only to discover that each airframe had been virtually built by hand and therefore no two were exactly alike, or at least the differences were far outside their tolerances. Is this true?
 

Zootycoon

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In a word no, but it’s a bit more complicated that just a word.

BTW the following is not a second hand repeated story or something I’ve read somewhere.

Back in 1965, all production Nimrods were built on a common set of jigs that was specifically purchased by the MOD to support the project thereby maximising part interchange. At the beginning of Nimrod 2000, the original MR1 jigs still existed as they were stored at Aston Down, but having been stored outside they had deteriorated to the point of being unusable.

That said the fleet was small so the MOD accepted hand formed compound curved panels in a the fuselage up sweep areas, principally the nose and tail. This meant a larger position tolerance for the fuselage frames in these locations as the frames had to be positioned where they touched the skins. Equipment mounted in these locations had the necessary adjustment built into it to cope with the frame position variation but items such as hydraulic pipes/electrical looms where individually made to fit. The fuselage between frames12 and frame 46 was built to the same tolerances as you find on a modern airliner.

At the beginning of Nimrod 2000 we were well aware of this. Indeed in the latter part of 1996 I was involved in a fleet measuring survey (using Portable Ziess laser measuring equipment) to validate the original build records. The often reported stories of discovery mid project, this causing the wings not to fit, and leading to the years of delay are utter nonsense.

MRA4 development issues which lead to its failure had nothing to do with the original build tolerances as is often claimed. The real story needs to be told I’ll find some time over the next few weeks to write some of it down.
 
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harrier

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I'd be interested to hear the true tale. An RAF desk officer told me that they knew they had an MR.1 that was a foot longer than the others. I also got some photos from Avro Heritage showing the moment the wings don't fit. Chap up a ladder looking at the camera with 'evils'.

Although the programme had a morass if issues, I always felt the same as Bill Gunston did about it: hard to believe anyone would get it so wrong as to make all the wings to fit a Comet on a fire dump.
 

Hobbes

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Harrier, did something go wrong when you posted your previous reply? All I see is a quote from Zootycoon...
 

Zootycoon

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PA1 wing center section was fitted to Fuselage on a (Thursday, I think) afternoon/evening overrunning it’s original allocated time by about six hours due to problems with tool access to the forward/aft tie rods pins. It’s absurd to claim you could see this moment in a photo. Equally it’s absurd to claim that a six hour build time overrun was responsible for a ten year delay. Please consider:- (not so) Smart Procurement, Unrealistic initial assumption of cost/as to where the engineers were coming from, leading to a slow ramp up in manpower, poor decision making during delays, leading to missed timing of production capacity, hence an inability to get parts to the assembly line, when built the flight test finding of an aileron control circuit that was too heavy leading to it being designed/made/qualified/flown two further times <each of these cycles taking about 18 months >and finally the referencing of the refuelling safety case to MR2 experience. = ten years of delay
(note also many of those involved knew that when this project was delivered they were redundant)

So many people have repeatedly claimed such nonsense about various aspects of the project it’s now very difficult for people to see truth.
 
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CJGibson

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You might like to read AM Sir Richard Johns' comments on the MRA.4 in the latest RAF Historical Society Journal.

Chris
 

CJGibson

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All true Zootycoon and it did carry some great kit, much of which is in Poseidon, but the airframe...

I quote Paul Calf verbatim.

Chris
 

harrier

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Harrier, did something go wrong when you posted your previous reply? All I see is a quote from Zootycoon...
Yes. New phone and fingers of a fool!
 

harrier

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PA1 wing center section was fitted to Fuselage on a (Thursday, I think) afternoon/evening overrunning it’s original allocated time by about six hours due to problems with tool access to the forward/aft tie rods pins. It’s absurd to claim you could see this moment in a photo. Equally it’s absurd to claim that a six hour build time overrun was responsible for a ten year delay. Please consider:- (not so) Smart Procurement, Unrealistic initial assumption of cost/as to where the engineers were coming from, leading to a slow ramp up in manpower, poor decision making during delays, leading to missed timing of production capacity, hence an inability to get parts to the assembly line, when built the flight test finding of an aileron control circuit that was too heavy leading to it being designed/made/qualified/flown two further times <each of these cycles taking about 18 months >and finally the referencing of the refuelling safety case to MR2 experience. = ten years of delay
(note also many of those involved knew that when this project was delivered they were redundant)

So many people have repeatedly claimed such nonsense about various aspects of the project it’s now very difficult for people to see truth.
So all the wings were fine?

All the stories and pictures I have came from those involved.
 

Zootycoon

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Harrier
I don’t really care about what you’ve told, I’m only telling you what I saw.
 

harrier

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Harrier
I don’t really care about what you’ve told, I’m only telling you what I saw.
And I only want to know the real story. I don't think we have it, but I did do some work with the Nimrod design team at the time and saw some things too. For getting things like Team Tempest right this stuff needs to come out so I am very happy to hear about what you saw.
 

PMN1

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Would be interesting to know the full story....especially given the speed the airframes were cut up.

An interesting thing that cropped up over on the History Politics and Current Affairs board is that the B.1. seems to have similar issues to that reported on the Nimrod with individual aircraft being different.

'He said the manufacturing process for building the B1s was so chaotic that each B1 is essentially custom built and that there are a lot of parts that are not interchangeable. They are a maintenance nightmare. I believe on some the retractable wings are very unreliable.'

"The situation has gotten so bad, according to the subcommittee, that the number of B-1 aircraft that are fully mission-capable is now only in the single digits'
 
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Hood

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Well its the classic case of everyone who was present having a different story to tell. No group of eyewitnesses ever have the same story in within a large organisation, not everyone is fully aware what other groups are doing.
But I am with harrier, it would be good to hear the true tale and understand where all these myths came from.
 

Zootycoon

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PMN1
Exactly, this whole thing is blown out of all proportions by people who don’t understand the grim reality of building small fleets. Not to mention that even on modern big fleets, claims of amazing interchangeable are without validation, to the best of my knowledge, no A320 has ever flown again after having its wings taken off/reinstalled, let alone flown with another’s/replacement set.

In designing your small fleet solution you put in the necessary adjustments and live with it. It’s well known both to the engineers who design/operate it and to the customer that buys it. Just because joe public might be shocked that it’s not like their Merc/Ford doesn’t warrant nonsense claims of how incompetent everyone was.

Tech such as fly by wire can help as it’s not so dimensional critical but there again welcome to the deep joy of component obsolescence.
 
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Zootycoon

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Nimrod’s wing structure was unlike that found on a modern low wing airliner in that its central torque box was integral to the wing structure . The fuselage has a pressure load bearing floor above the cut out, through which the wing passed. The A400m/146/ATR42/72 are a little similar but as high wing architectures. The modern A or B team airliner has the torque box is integrated into the fuselage and a LH/RH are attached by hundreds/thousands of bolts with the gaps taken out by shim strips..... yes that’s right shims.

Nimrods wing attaches to the fuselage at just eight locations, the “cathedral” fuselage fitting to forward edge of the torque box( 8 x15/16 bolts in two groups port/Starboard), this joint includes machined shims to ensure the z gap is correct (prepared from measurements taken before hand), then at the aft of the torque box there’s two vertical links, pin joints at both ends, oversized bushes hand reamed to final pin fit size. On the back of the torque box is the shear fitting, shimmed it the x axis then straight pin jointed. Finally there’s four shackle links which go between the lower torque box and fuselage, two forward and two aft, again oversize bushes hand reamed to final pin size. I remember access problems leading to oversize reaming, difficulties with spanner removal once some of pin nuts were tightened but nothing that resulted in a more than a few hours delay. Indeed I always thought with this wing/fuse joint there was more latitude to accommodate tolerance variation than the other types ..... so the often claimed wings didn’t fit which killed the project or sized to Comet in the scrap compound .....no just didn’t happen.....indeed pretty insulting to the professionals involved.
 

CJGibson

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As far as I was aware wing fit was never a problem - tabloid bolleaux like the Typhoon name - and I say nothing about that in Nimrod's Genesis. Was never mentioned on my visits to Woodford. However, burying BR710s and fitting around them was. You'd think that the feature that killed the Comet (aside from metal fatigue, discuss) as an airliner and made the 707 and DC-8 (and every other airliner since) successful would have had some influence on the design team. After all they had previously drawn up a Nimrod with four externally hung RB.410s. The question that should be asked here is why was burying the 30% larger engines considered a good idea?

Chris
 

kitnut617

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Chris, are there any basic drawings of the MR.4 wing that could be used to produce a decent model of it ?
 

zebedee

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but there again welcome to the deep joy of component obsolescence.
Not to mention software development!
Don't get me started... my exceptionally brief brush with the project was in 2006. A friend of my then girlfriend was working on the maintenance e-learning materials at Warton and as I was then heavily involved in e-learning design a visit to have a look at the system in development was arranged during the 2006 Friends and Family day. I was somewhat shocked to discover the system had been written in a programme (Adobe/Macromedia Authorware*) that hadn't been updated in over three years and was widely expected in the community to be for the chop, in fact being end of lined less than 12 months later...

Zeb

*not a fun programme to use... the only thing I ever produced in it was a guide to Equine Neuroanatomy but thats another story...
 

CJGibson

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Kitnut - I've only seen the published GAs, nothing detailed. Probably all been shredded!

Chris
 

kitnut617

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Thanks Chris and that is a pity, I would really like to convert one of my models into the MR.4

Robert
 

Caravellarella

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Thanks Chris and that is a pity, I would really like to convert one of my models into the MR.4

Robert
Do you really kitnut617; it's such a odd-looking aircraft (subjectively). I worked on the MR.4 presentation models in 1/100 scale in a previous career; I recall we had to produce new moulds for the entire model as it was impossible design the new wings to fit our existing Nimrod fuselage mouldings. We also produced the MR.4s in 1/24 (or was it 1/36?) scale, it was a long time ago now......

Terry (Caravellarella)
 

Caravellarella

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Dear Boys & Girls, is there any truth in the "story" (recounted by my late best friend) that one of the MR.4 airframes was dropped onto the floor of an anechoic chamber/hangar at Woodford. It fell some height and was damaged beyond repair; perhaps it fell from a hoist or was knocked-off trestles/stands (I don't know the correct jargon).

Terry (Caravellarella)
 

Zootycoon

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BAe Nimrod replacement effort started in 88/89 and was initially focused on the mission system. Air vehicle considerations commenced a few years latter. My first contact with the Regional Maritime Patrol Aircraft (RMPA) project was in 1993 as part of the A321 study. I contributed to the study but never saw the final report. Despite initial hopes that an A321 conversion would be straight forward we quickly discovered it was anything but. Work came to an abrupt halt and we were told that the RAF/MOD would not accept anything with less than four engines. You must remember that EROP’s hadn’t really started, many people where questioning its wisdom, the RAF were going a long into the South Atlantic and their normal operation spent a long time below 1000ft amongst the sea birds. The following year I started work on what was to eventually become A400m in preparation for a project launch. As if by magic, there was RMPA again, by now the preferred air vehicle albeit with some reservations concerning low frequency propeller noise. A400m’s major challenge for RMPA was the delivery schedule whereby the partners would only agree to delivering aircraft for conversion until the at end of their own deliveries. This gave an IOC of 2010 at the earliest, very likely latter and Nimrod MR2 just couldn’t wait that long. So the solution was a mid life update for MR2 to bridge the gap. And that’s where the seed of a Nimrod recondition/modification program was planted. Of course come early 95 the launch of A400m stalled, the RAF/MOD had allocated funds for a Nimrod replacement and the favourite for the role was dead.

More to follow.
 
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Foo Fighter

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You might like to read AM Sir Richard Johns' comments on the MRA.4 in the latest RAF Historical Society Journal.

Chris
Is that publication available pdf wise or is it only in printed format?
 

gwiz

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As I recall, the MRA.4 was to have new wings with the parts outboard of the engines built to the same external shape as the original Nimrod, ie 1940s Comet vintage. This was because by the time that Plan A to re-use the original wings was abandoned, there wasn't time to do an aerodynamic redesign. This did not sit well with the BAe wing aero designers who had produced the state-of-the-art Airbus wings. In 1999, I was in line to do a complete drag audit of all the MRA.4 aerials and other bits and bobs, rather a lot of those, but was shifted to another job in the nick of time.
 

PMN1

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After all they had previously drawn up a Nimrod with four externally hung RB.410s. The question that should be asked here is why was burying the 30% larger engines considered a good idea?

Chris
When was that done?

Was they attached directly to the wing or via a pylon?

Were they hung under the wing in the same position the buried engines were or elsewhere under the wing?
 

Hobbes

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As far as I was aware wing fit was never a problem - tabloid bolleaux like the Typhoon name - and I say nothing about that in Nimrod's Genesis. Was never mentioned on my visits to Woodford. However, burying BR710s and fitting around them was. You'd think that the feature that killed the Comet (aside from metal fatigue, discuss) as an airliner and made the 707 and DC-8 (and every other airliner since) successful would have had some influence on the design team. After all they had previously drawn up a Nimrod with four externally hung RB.410s. The question that should be asked here is why was burying the 30% larger engines considered a good idea?

Chris

Bill Gunston's book, 'Nimrod, the centenarian aircraft' says the underwing engines were rejected as 'the tailplane couldn't handle the increase in pitch moment from the lower thrust lines'.
 

kitnut617

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Thanks Chris and that is a pity, I would really like to convert one of my models into the MR.4

Robert
Do you really kitnut617; it's such a odd-looking aircraft (subjectively). I worked on the MR.4 presentation models in 1/100 scale in a previous career; I recall we had to produce new moulds for the entire model as it was impossible design the new wings to fit our existing Nimrod fuselage mouldings. We also produced the MR.4s in 1/24 (or was it 1/36?) scale, it was a long time ago now......

Terry (Caravellarella)
Well I bought enough Airfix kits of the Nimrod to make all the different variants when they first introduced it, I just didn't think it would be that hard to find detail drawing of the MR.4 after it got cancelled --- Plus styrene is easily cut up and modified ;)

What company did you work at when you built the models Terry ? if you don't mind me asking.

I've read that the MR.4 was designed to take Spey engines, I've also read that the Nimrod R.1 also was powered by Speys but that aircraft didn't need new wings --
 

TomS

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I've read that the MR.4 was designed to take Spey engines, I've also read that the Nimrod R.1 also was powered by Speys but that aircraft didn't need new wings --
All of the Nimrods before MR.4 used Spey engines. It was the MR.4 that was going to change to the BR710 engine.
 

zebedee

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Dear Boys & Girls, is there any truth in the "story" (recounted by my late best friend) that one of the MR.4 airframes was dropped onto the floor of an anechoic chamber/hangar at Woodford. It fell some height and was damaged beyond repair; perhaps it fell from a hoist or was knocked-off trestles/stands (I don't know the correct jargon).

Terry (Caravellarella)
Pure conjecture but UK serials lists the conversion of PA12 (XV246/ZJ525) as being cancelled as donor airframe was unsuitable... A refurbished PA3 then took its place as PA13... maybe it was that one...?

Zeb
 

Zootycoon

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As I recall, the MRA.4 was to have new wings with the parts outboard of the engines built to the same external shape as the original Nimrod, ie 1940s Comet vintage. This was because by the time that Plan A to re-use the original wings was abandoned, there wasn't time to do an aerodynamic redesign. This did not sit well with the BAe wing aero designers who had produced the state-of-the-art Airbus wings. In 1999, I was in line to do a complete drag audit of all the MRA.4 aerials and other bits and bobs, rather a lot of those, but was shifted to another job in the nick of time.
At contract award 1996 the wing panels outboard of the landing gear was retained/reconditioned structure. One of the first actions the guys in the wing design preformed was a cost benefit analysis which recommended new build outer panels. Except tank 4a the podded tanks that stick out from the leading edge;- history proved it cost a lot more to recondition and modify these than to make new ones.

The wing outboard of the engines at contract award was just an enlargement of the MR2 in just about every respect. But Warton performance group had used a wing mass derived from a scaled up A320 structure. This was about 1.5 tons less than the enlarged MR2 structure because it was fully optimised which doesn’t happen if you just use a photocopier to make drawings bigger. So when this became apparent the wing team made two proposals;- an enlarged but heavy wing delivered to Woodford June 1998, or an fully optimised weight (as per A320 design practice i.e a different number of ribs/stringers) wing, which would be delivered to Woodford Nov 1999. The project had become aware of the first schedule slip (more on this in another post), Warton needed the lighter wing to achieve performance so they instructed the wing team to proceed with the simple, enlarged MR2 but finesse (very local optimisation) at least a ton out of it and deliver it no later than the end of 1998. Come the critical date only a couple of hundred Kg had come out but aircraft Warton performance department demanded the lower weight, so a further delay was approved for more finessing. In the end the requested weight was never achieved by quite a long way but the drag model was revised down (I expect ithis is the drag audit gwiz is referring to as it fits the timing) which compensated ..... The first wing was delivered to Woodford in Oct 1999.

The significance of this, is its impact on part manufacturing because we had missed the vital pre Typhoon ramp up lull at Brough/Salmsbury. There wasn’t the cash to go outside of BAE and now there was no machining capacity inside. Hence significant part supply shortages which crippled the first aircraft build for the next three years.

I was latter told (although I never saw the data) that the revised drag estimate in1999, and subsequently confirmed by flight test would have allowed the enlarged but heavy wing to meet all the performance requirements.

But there were problems with the supply of data for manufacture coming from other understaffed area because you can’t just magic skilled people out of thin air.
 

Caravellarella

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Thanks Chris and that is a pity, I would really like to convert one of my models into the MR.4

Robert
Do you really kitnut617; it's such a odd-looking aircraft (subjectively). I worked on the MR.4 presentation models in 1/100 scale in a previous career; I recall we had to produce new moulds for the entire model as it was impossible design the new wings to fit our existing Nimrod fuselage mouldings. We also produced the MR.4s in 1/24 (or was it 1/36?) scale, it was a long time ago now......

Terry (Caravellarella)
Well I bought enough Airfix kits of the Nimrod to make all the different variants when they first introduced it, I just didn't think it would be that hard to find detail drawing of the MR.4 after it got cancelled --- Plus styrene is easily cut up and modified
;)

What company did you work at when you built the models Terry ? if you don't mind me asking.

I've read that the MR.4 was designed to take Spey engines, I've also read that the Nimrod R.1 also was powered by Speys but that aircraft didn't need new wings --


Space Models Ltd of Feltham, Middlesex kitnut617......

Terry (Caravellarella)
 

CJGibson

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Maybe look back at the thinking behind the MRA.4? Pure parochial politics. Why take a 40 (50?) year-old design and update it? B-52 - hang new turbofans on it. C-130 - stick new turboprops on it. Ditto P-7. P-8 - mate wings and modded fuselage of same basic aircraft. None required the complete redesign of the engine installation and wing. The MRA. 4 sounded great on paper but like many aerospace projects nobody said 'Stop this nonsense' until it was too late.

Are we turning this beast into a millennial TSR. 2?

Chris

Ps - why did it need four engines anyway (rhetorical question, but I'm interested in the answers)
 

Zootycoon

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As far as I was aware wing fit was never a problem - tabloid bolleaux like the Typhoon name - and I say nothing about that in Nimrod's Genesis. Was never mentioned on my visits to Woodford. However, burying BR710s and fitting around them was. You'd think that the feature that killed the Comet (aside from metal fatigue, discuss) as an airliner and made the 707 and DC-8 (and every other airliner since) successful would have had some influence on the design team. After all they had previously drawn up a Nimrod with four externally hung RB.410s. The question that should be asked here is why was burying the 30% larger engines considered a good idea?

Chris

Bill Gunston's book, 'Nimrod, the centenarian aircraft' says the underwing engines were rejected as 'the tailplane couldn't handle the increase in pitch moment from the lower thrust lines'.
The normal problem is not with pitch, but with yaw in the case of the failure of an outboard engine on take off and therefore at max thrust The one good feature of Nimrod/Comet engine architecture was a nice small (low parasitc drag) fin.

In reply to another post concerning the MR4 designed to accommodate Spey,.....No
 
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Zootycoon

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why did it need four engines anyway (rhetorical question, but I'm interested in the answers)
At the time the RAF didn’t believe in ETOP’s, there were too many horror stories of Nimrod’s limping back hundreds of miles with engines taken out by bird strikes and the south Atlantic is a very unforgiving place to be a long way from home flying a single.

I see their point as the basic ETOPs safety case doesn’t have a bird strike risk and has minimal change in engine thrust, it’s a very constant environment unlike low level.
 
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