Nimrod MRA.4
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Does the age of the frame matter that much? If the frame is taken back to bare metal, inspected and relifed before being reconstructed, where is the problem? If some systems are carried over and not modernised, I can see that being a problem, but I thought it was a ground-up rebuild with basically just the fuselage framework being carried over. Is that not the case? One of the things I see as frequent SLF that gives me a reasonable feel for the age and condition of the ac is the condition of the door area on entering. Old beater DC-9s and MD-88s have more coats of paint than a Navy ship, and the rubber seals are often in rag order. Lo and behold, the rest of the interior usually follows suit. Are the MRA4s being reworked to that extent?
I do see that the frame is perhaps too small in cross-section to begin with, but that's a different issue than if it's knackered or not. Never been in a Nimrod, but I did fly in a Dan-Dare Comet as a kid, and again about 10 years ago went on the Comet at Duxford. What struck me was how small it was.
Sorry for the noddy contribution, I know sod all about Nimrods, but the basic idea seems pretty simple.
I do see that the frame is perhaps too small in cross-section to begin with, but that's a different issue than if it's knackered or not. Never been in a Nimrod, but I did fly in a Dan-Dare Comet as a kid, and again about 10 years ago went on the Comet at Duxford. What struck me was how small it was.
Sorry for the noddy contribution, I know sod all about Nimrods, but the basic idea seems pretty simple.
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Having operated PA1, PA2, PA3, ZJ514 and ZJ515 since 2007 (does that qualify me to express an opinion?) I am beginning to tire of those who persist with the line that MRA4 = MR2 with a new paint job and some re-lifed/modified systems.
Roadster280 is correct in his statement concerning the treatment of the 4% retained structure (note I said structure not systems) that come from MR2 and contribute to each MRA4. For those not convinced I recommend a trip to Woodford, you may learn something.
Those closely involved eagerly await A's return to flight status and the types RTS. None of us consider it a half-baked upgrade - it is a new aircraft, and long overdue.
Roadster280 is correct in his statement concerning the treatment of the 4% retained structure (note I said structure not systems) that come from MR2 and contribute to each MRA4. For those not convinced I recommend a trip to Woodford, you may learn something.
Those closely involved eagerly await A's return to flight status and the types RTS. None of us consider it a half-baked upgrade - it is a new aircraft, and long overdue.
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MRA4 New Systems
I agree that it is a new aircraft and long overdue, but it still has to make it past October.
Undoubtably it could be a very capable aircraft if it gets in service and the mission systems finally get a good work out. I was told in a presentation at ABW that a large amount of testing had been defered until the aircraft was delivered to the RAF (to save money).
However, when you make decisions like that what come back do you have on BAE when things may not work as described when systems are fully loaded?
Integrated Operational Test and Evaluation was supposed to be the panacea to things like the "Blue Circle" Tornado F radar, but as soon as the military starts running short of money then things get chopped at the expense of capability.
Frustrated....
Undoubtably it could be a very capable aircraft if it gets in service and the mission systems finally get a good work out. I was told in a presentation at ABW that a large amount of testing had been defered until the aircraft was delivered to the RAF (to save money).
However, when you make decisions like that what come back do you have on BAE when things may not work as described when systems are fully loaded?
Integrated Operational Test and Evaluation was supposed to be the panacea to things like the "Blue Circle" Tornado F radar, but as soon as the military starts running short of money then things get chopped at the expense of capability.
Frustrated....
I don't own this space under my name. I should have leased it while I still could
I do see that the frame is perhaps too small in cross-section to begin with, but that's a different issue
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PN
A tin can analogy springs to mind. Why do we recycle tin cans? Why don't we just wash, check for corrosion and distortion, refill and reuse?
As I previously stated, when I saw the first 3 airframes at Bournemouth being cleaned & stress tested, the techies were more than satisfied that the airframes were 5x thicker & stronger than necessary, a consequence of the way aircraft were virtually hand built in the 50s & 60s.
It wasn't the airframe that caused the problems over Afghanistan.
I don't own this space under my name. I should have leased it while I still could
fin, very true but I was riposting to 'where's the problem?'
The problem is the same as the tin-can; the fuselage had to be rigorously inspected before re-use rather than being melted down and recyling. One hopes that someone did a cost-benefit analysis to prove that reuse was cheaper than new build. Personnally I have doubts as it was probably costed to prove that reuse was a better option rather than a proper, unbiased, clean sheet approach.
I have asked the question in the past why we seemed to junk and go for new-build when the cousins had a well established practice of reuse. Since then of course we have had the GR1-GR4 and the GR1-GR3 also the GR7-GR9, all rebuilds and updates. On that basis the MR1-2-3-4 process is in keeping with that frugal approach.
In the MRA4 however I suspect that it might have been an economy too far and actually cost more but then I have no facts.
The problem is the same as the tin-can; the fuselage had to be rigorously inspected before re-use rather than being melted down and recyling. One hopes that someone did a cost-benefit analysis to prove that reuse was cheaper than new build. Personnally I have doubts as it was probably costed to prove that reuse was a better option rather than a proper, unbiased, clean sheet approach.
I have asked the question in the past why we seemed to junk and go for new-build when the cousins had a well established practice of reuse. Since then of course we have had the GR1-GR4 and the GR1-GR3 also the GR7-GR9, all rebuilds and updates. On that basis the MR1-2-3-4 process is in keeping with that frugal approach.
In the MRA4 however I suspect that it might have been an economy too far and actually cost more but then I have no facts.
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PN
In the MRA4 however I suspect that it might have been an economy too far and actually cost more but then I have no facts.
For a non-engineer, but with some experience of the aircraft industry production controlling nose and visor assemblies for Comncorde, can someone explain in simple terms how the fuselaes all came out with different dimensions
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how the fuselaes all came out with different dimensions
FC84 - thanks - but if all the components and then assemblies and so on were to drawing and passed inspection, I am surprised (at the layman level) at the amount of discrepancy. C'est la vie.
I don't own this space under my name. I should have leased it while I still could
Wanderer, the aircraft was designed by De Haviland and modified by Hawker Siddley before BAC became BAE and remodled it as the MRA4.
Hawker Siddley built the Nimrod using a largely Avro workforce. Do you begin to see a possible problem?
Avro had built the Vulcan and its design included an offset doppler bay. The doppler had to be accurately aligned with the aircraft centre line and this was done with sighting rods, a datum compass and a tape measure.
Having found the true centre line the datum compass and tape measure were used to find the offset centreline. The offset was in the order of 15 feet 2 and a quarter inches but varied, IIRC, by upwards of an inch.
Hawker Siddley built the Nimrod using a largely Avro workforce. Do you begin to see a possible problem?
Avro had built the Vulcan and its design included an offset doppler bay. The doppler had to be accurately aligned with the aircraft centre line and this was done with sighting rods, a datum compass and a tape measure.
Having found the true centre line the datum compass and tape measure were used to find the offset centreline. The offset was in the order of 15 feet 2 and a quarter inches but varied, IIRC, by upwards of an inch.
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Bendy plywood jigs? I wonder how they (DH) got on with the Mosquito then? Maybe all the stock moved at the same rate.
PN - I wasn't having a go at you personally. An analogy of mine - isn't it a bit like say the Firth of Forth rail bridge? Built a lot longer than any aircraft ago, engineered to nth degree after the collapse of its predecessor, and still in use today. Gets painted and inspected constantly. If you were building the same bridge today, I am sure it would be a lot smaller and less materials-intensive. In those days though, it was more expedient to use more metal than work out how little you could get away with. I suspect the Nimrods (especially after the early Comet experiences) were similarly belt, braces AND a piece of string.
PN - I wasn't having a go at you personally. An analogy of mine - isn't it a bit like say the Firth of Forth rail bridge? Built a lot longer than any aircraft ago, engineered to nth degree after the collapse of its predecessor, and still in use today. Gets painted and inspected constantly. If you were building the same bridge today, I am sure it would be a lot smaller and less materials-intensive. In those days though, it was more expedient to use more metal than work out how little you could get away with. I suspect the Nimrods (especially after the early Comet experiences) were similarly belt, braces AND a piece of string.
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Wander00
but if all the components and then assemblies and so on were to drawing and passed inspection, I am surprised (at the layman level) at the amount of discrepancy. C'est la vie.
I don't own this space under my name. I should have leased it while I still could
Roadster, never thought you were, boot and other foot maybe 
However the practice of upgrading an airframe was one I saw the USAF did frequently with the Buff though they did stop short of re-engining the beast and I thought we threw airframes away too soon.
But with the Nimrod it certainly had lots of corrosion issues on the Mk 2 in, IIRV, the galley and the toilet area. Same stable as the Dominie and when they took that apart they found that the hidden parts of the fuselage had bad corrosion and had never been painted properly.
However the practice of upgrading an airframe was one I saw the USAF did frequently with the Buff though they did stop short of re-engining the beast and I thought we threw airframes away too soon.
But with the Nimrod it certainly had lots of corrosion issues on the Mk 2 in, IIRV, the galley and the toilet area. Same stable as the Dominie and when they took that apart they found that the hidden parts of the fuselage had bad corrosion and had never been painted properly.
I recall ferrying a Nimrod from Malta to Kinloss for a major service. We were later told that there were thoughts of scrapping it due to the amount of corrosion inside the wings.....
, apparently you could push a pencil through some of it 
. ....
.... and this was a Mk.1 in the mid-70's
, apparently you could push a pencil through some of it . ........ and this was a Mk.1 in the mid-70's
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and this was a Mk.1 in the mid-70's