Nimrod MR4 vs P8
One of the reasons why a modern airliner is so much more efficient in its intended role than the 1950s incarnations is simply what you say - computer-aided engineering. We can now do stressing down to the individual part with decidedly complex load-paths and so very little of the airframe is only along for the ride - it all contributes. So the airframe is optimised to a MUCH higher degree than those of yesteryear. Heck, you only have to watch one fly through a mild bit of wake turbulence and the wings are flapping around like the tacoma narrows bridge.
In the Comet era we lacked the ability to do the hundred billion calculations needed to fully understand the stresses reacted by many curved surfaces and components. So the aeroplane structure was comprised of a "primary structure" of largely straight and easily-calculated elements with simple load paths wrapped up in an aerodynamic fairing of "secondary structure". By the 1950s we had started including *some* of the structural properties of the secondary structure, but only through what were essentially rules of thumb and so the values were heavily "discounted" in the stressing cases.
As a result the Nimrod was (compared to a modern airliner) built like a brick outhouse. And that's the primary reason why it was easily adaptable to the low-level manoeuvering needed for the ASW role. Not that it's that relevant for the MRA4, because that had an entirely new wing which was designed explicitly for the stresses of that role - something which could not be said of any current airliner.
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.
PDR
Last edited by PDR1; 4th May 2017 at 16:42.
From my paper* (copyright PDR!):
* Dissertation on the engineering implications of moves towards availability/capability contracting in the UK Defence sector. Unavailable from all good bookshops, its 226 pages and 54,000 randomly-selected words are currently believed to be mankind's most demonstrably effective treatment for insomnia.
PDR
There is a fundamental difference between equipment acquisition and availability/capability contracting. In an equipment acquisition programme the user is paying the contractor to deliver something that is fit for purpose, but it largely can be tested prior to using it on the Mission to confirm that the contractor delivered what was required. In an availability/capability programme the contractor is being paid to be an active part of the Mission, or at the very least the ability to sustain Mission Capability. One of the stated objectives of moving to Availability/Capability contracting is to transfer risk to the contractor, and with that risk goes responsibility.
But in the military scenario the full risk can never be transferred to a contractor. There is a traditional proverb, usually assumed to relate to the fate of King Richard III at the Battle of Bosworth[1]:
For want of a nail, the shoe was lost;
For want of the shoe, the horse was lost;
For want of the horse, the rider was lost;
For want of the rider, the battle was lost;
For want of the battle, the Kingdom was lost;
And all for the want of a horseshoe nail.
Although this proverb is usually cited to emphasise the need to attend to details, to the ILS community it illustrates the chain of causation between component failure and mission loss. If there had been an effective LSA programme the end effects of the nail failure mode would have been analysed in a FMECA, together with a probability of occurrence predicted in reliability analysis and verified through analogy or demonstration. The RCM analysis would have determined whether preventive inspections or lifing of the horse-shoe subsystem components were warranted and the maintainability analysis would have established the required inspection and rectification procedures together with the skills, equipment, spares, consumables and facilities required to achieve them. The level of repair analysis would then have ensured that the appropriate support policies were implemented to reflect the tolerable resource burden for the mission criticality of the horse. In short; King Richard’s horse would have been returned to serviceability (or replaced) within the time required to prevent a Mission failure. Rather than cry: “A horse, a horse; my Kingdom for a horse!”, supportability engineers would point out that he should have cried:
“A capable system, a capable system, my Kingdom for an increased investment in early-phase LSA during the procurement process to assure the most cost-effectively sustainable through-life Capability at Readiness!!”
But admittedly this does not have the same ring to it and would be difficult to render into iambic pentameter.
All of these analyses are based on probabilities and trade-offs between the cost and consequence of Mission Failure, and only the Mission Owner (the one who has the original political or economic need for the Mission) can own this risk. If King Richard’s personal transport had been provided by way of a “Horse Availability Service” it is doubtful that the commercial performance penalties resulting from the first-line mission availability failure would be regarded as an adequate compensation for the Plantagenet dynasty’s permanent loss of the English throne. This could be seen as a general characteristic of military missions that is rarely (if ever) present in non-military missions, and it is the reason why the Author would suggest the “blind” application of commercial models to military systems is probably naïve.
[1]Although this is unlikely since King Richard’s horse was actually stuck in deep mud rather than rendered unserviceable through the loss of a shoe, and some versions of the proverb are known to predate him
But in the military scenario the full risk can never be transferred to a contractor. There is a traditional proverb, usually assumed to relate to the fate of King Richard III at the Battle of Bosworth[1]:
For want of a nail, the shoe was lost;
For want of the shoe, the horse was lost;
For want of the horse, the rider was lost;
For want of the rider, the battle was lost;
For want of the battle, the Kingdom was lost;
And all for the want of a horseshoe nail.
Although this proverb is usually cited to emphasise the need to attend to details, to the ILS community it illustrates the chain of causation between component failure and mission loss. If there had been an effective LSA programme the end effects of the nail failure mode would have been analysed in a FMECA, together with a probability of occurrence predicted in reliability analysis and verified through analogy or demonstration. The RCM analysis would have determined whether preventive inspections or lifing of the horse-shoe subsystem components were warranted and the maintainability analysis would have established the required inspection and rectification procedures together with the skills, equipment, spares, consumables and facilities required to achieve them. The level of repair analysis would then have ensured that the appropriate support policies were implemented to reflect the tolerable resource burden for the mission criticality of the horse. In short; King Richard’s horse would have been returned to serviceability (or replaced) within the time required to prevent a Mission failure. Rather than cry: “A horse, a horse; my Kingdom for a horse!”, supportability engineers would point out that he should have cried:
“A capable system, a capable system, my Kingdom for an increased investment in early-phase LSA during the procurement process to assure the most cost-effectively sustainable through-life Capability at Readiness!!”
But admittedly this does not have the same ring to it and would be difficult to render into iambic pentameter.
All of these analyses are based on probabilities and trade-offs between the cost and consequence of Mission Failure, and only the Mission Owner (the one who has the original political or economic need for the Mission) can own this risk. If King Richard’s personal transport had been provided by way of a “Horse Availability Service” it is doubtful that the commercial performance penalties resulting from the first-line mission availability failure would be regarded as an adequate compensation for the Plantagenet dynasty’s permanent loss of the English throne. This could be seen as a general characteristic of military missions that is rarely (if ever) present in non-military missions, and it is the reason why the Author would suggest the “blind” application of commercial models to military systems is probably naïve.
[1]Although this is unlikely since King Richard’s horse was actually stuck in deep mud rather than rendered unserviceable through the loss of a shoe, and some versions of the proverb are known to predate him
PDR
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I am impressed ... not least by the fact that I understood some of it! Thanks, PDR1 ^
Thread Starter
A couple of relevant points from Tony Blackman's book.
The Nimrod was no 'bodged up Comet' from all accounts the MR2 was a superb
aircraft in its role, from its high speed transit ability to the flexibility it offered
with the huge installed bomb bay and the variety of sensors on board, it seems
to have been a very effective platform.
The AEW version really was a disaster and the technical problems were never worked
out.
The MRA4 on the other hand was 'ready to go' all issues, such as bespoke fittings
had been worked out and the sensor suite was first rate, Tony claims it was a better
aircraft than the P8 and it's performance was outstanding, also it would have kept
that huge bomb bay, far bigger than the P8 along with wing hard points it could
carry an impressive amount of weapons and / or rescue gear.
This is all from his book, i'm no expert but it appears the real reason the MRA4 was cancelled was a temporary budget shortfall, nothing to do with technical shortcomings.
It also had a MAD boom as standard, unlike the P8 which will end up costing more anyway.
The Nimrod was no 'bodged up Comet' from all accounts the MR2 was a superb
aircraft in its role, from its high speed transit ability to the flexibility it offered
with the huge installed bomb bay and the variety of sensors on board, it seems
to have been a very effective platform.
The AEW version really was a disaster and the technical problems were never worked
out.
The MRA4 on the other hand was 'ready to go' all issues, such as bespoke fittings
had been worked out and the sensor suite was first rate, Tony claims it was a better
aircraft than the P8 and it's performance was outstanding, also it would have kept
that huge bomb bay, far bigger than the P8 along with wing hard points it could
carry an impressive amount of weapons and / or rescue gear.
This is all from his book, i'm no expert but it appears the real reason the MRA4 was cancelled was a temporary budget shortfall, nothing to do with technical shortcomings.
It also had a MAD boom as standard, unlike the P8 which will end up costing more anyway.
This is all from his book, i'm no expert but it appears the real reason the MRA4 was cancelled was a temporary budget shortfall, nothing to do with technical shortcomings.
MRA4 was cancelled to fix a cash-flow problem. As has been shown many times, continuing with the MRA4 would (in overall cost terms) have been cheaper than the subsequent P8 procurement, and whilst I haven't seen the full P8 spec I am led to believe the overall mission capability of the MRA4 was significantly greater - especially when you consider that the MRA4 was equipped to take over the whole of the MR2 role (including all the non-sub-hunting and non-maritime roles) which I gather the P8 isn't.
PDR
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The issue with the AEW Nimrod was that the MoD tried to play the role of Prime Contractor and System Integrator, something that they had no relevant skills or experience in doing and so they made a right royal balls-up of it.
As someone who was on the AEW trials team, I can state with some authority that you are so far off the mark with that comment.
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The problem with the A319 MPA is that it is a paper aeroplane - it doesn't exist in any form that potential customers can touch it, feel it and assess its actual performance. This is why it lost to the P-8 in the competition in India - I'm led to believe!
Any first customer is going to have to pay for all of the D&D and T&E costs for a potential sale of a handful of aircraft. Unless Airbus invest company money to build a demonstrator, then its unlikely to rack up any sales.
As for the Mighty Hunter Mks 1 & 2, that was a brilliant and very capable platform. MRA4 had lots of issues still to be resolved and was never going to sell anywhere other than the UK. Cancellation was probably inevitable despite its apparent potential; it did have better performance than the P-8 particularly weapons carried, range and endurance.
Out of interest, what is your evidence for that?
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And the airworthiness world was in a state of churn with the MAA standing up. The understanding from the projects that I worked on at this time was that the evidential bar was being lifted considerably higher.
But of course at that time (late 2010) the Harier, Tornado, Typhoon and various helicopters didn't meet sthe subsequent regulations either.
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The real question is whether, after the introduction of the new standards, it would have been possible to generate the required documentation then.
The advice I'm given by members of the project team who are still colleagues is "yes, there were no fundamental blockers, although it would have cost quite a lot".
But of course at that time (late 2010) the Harier, Tornado, Typhoon and various helicopters didn't meet sthe subsequent regulations either.
PDR
The advice I'm given by members of the project team who are still colleagues is "yes, there were no fundamental blockers, although it would have cost quite a lot".
But of course at that time (late 2010) the Harier, Tornado, Typhoon and various helicopters didn't meet sthe subsequent regulations either.
PDR
In 2010 there was no money in the MoD, we were deep in the Dwang. Projects were being asked to give up money, a request for more would have been unwelcome.
There was no immediate need for legacy programmes to meet the regulations but new projects had to meet it in full. I don't have first hand knowledge of the MRA4 either but Haddon Cave was likely casting a long shadow across the validity of any read across from earlier versions of the platform.
I also disagree with some elements of your civil/ military support concept. It is much easier and cheaper to run aircraft that have large fleets and a worldwide market to buy spares from. Although, I do accept the military usage spectrum does drive specific design requirements that preclude picking up an airframe in its entirety.
PDR
As someone who, on delivery, was the avionics trade manager at Waddington and who had spent the previous 2 years at Woodford, RSRE and OR60 in Main Building, I can fully agree with Wensleydale's comment.
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Based on personal experience, although not of the MRA4 project, I would agree with Wensleydale. Serving military on the trials teams were allowed a great deal of insight into the project and it was not unusual for project teams to ask for advice. On the large projects, the trials team often joined the project at the beginning.
Then there is the detail that often the military version of the aeroplane will have operating broader clearances than the civil version, so parts used in the military version have been exposed to environments and stresses which would cause them to be declared unservicable in the civilian environment. They are also maintained using different tools & procedures and to different schedules in the two environments, further adding to the difficulty in accepting they've been in a controlled environment.
Fundamentally the military version of a civil type is simply not just the same aeroplane in a combat jacket. It's a different aeroplane which is used and maintained differently, and that's where the comparison to "world fleets" just falls over.
But also civil and military support systems have fundamentally different objectives. A civil support system is focussed on minimising or eliminating the financial loss arising from a technical failure. It is predicated on the >99% true axiom that the consequences of any failure can be acceptably addressed by paying money to someone. The Military requirement is different - the loss of a mission can mean people die and wars are lost, so no amount of money will fix it.
PDR
* My last direct involvement with this was about four years ago, so it may now finally have changed