BAE SYSTEMS Nimrod MRA.4

It was in the early requirements for Nimrod to perform bomber duties for internal security.
Yes it was, coming to think of it. The Shackletons were used to a great degree in conflicts in the Middle East, using bombs and strafing targets with the nose mounted guns. It makes sense, considering that that these aircraft were operating against insurgents, and could loiter for extended periods of time above their positions. It makes sense, although the pulling out of various colonies would make such a use rarity. It is a detail often forgotten about when talking about both the Shackleton and the Nimrod.
We had Shackleton's as ground training airframes, I'm guessing the navigator got to service the 2 x20mm guns in the nose, great view from there(all the 'avionics' were either side of the 'bed' you could lie on)., but must have been 'exciting' straffing armed insurgents, many miles from home, at low level......

Bombing would make a bit more sense.

And a 40 year old shack smells great, all that leather/oil/fuel...brings back memories.
 
On another tangent, was there ever any interest in a V bomber MRA? Lots of loiter ability there.


OK, found it.

Didn't they used Victors for the maritime reconnaissance job, in the 70's ? Not "full" MRA however, in the sense of chasing and killing subs...
Never heard of it, but I know that Vulcans used their radar to scan the surface back in the Seventies. It was mentioned in Nimrod's Genesis. It's been a while since I've read the book, so I do invite people to correct me if necessary.
 
One of the RAF Historical Society journals has a map showing how one high-level aircraft (Victors, I think from 543 Sqn originally, then Vulcans of 27 Sqn) with H2S could map the entire Norwegian Sea in a single sortie, and the patrol areas of half a dozen low-level Shackletons to positively identify the contacts.

I believe one of the advantages of Nimrod was that it could do both the high-level search and the low-level identification role when the MR.2 and Searchwater came in.
 
Flight Testing the Nimrod MRA4
Andrew Gill / Alex Bellamy
BAE Systems Flight Test (W427E)
Warton Aerodrome Preston, PR4 1AX United Kingdom
 

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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.
That design sounds to utterly weird to me. Very few planes are built that way, usually when the whole wing needs to be built in one piece for whatever reason. X-29's wing was one piece, so was Harrier II.
 
A similar need to the UK did lead to serious interest in a UK fighter for a while, at the same time as FS-X. There was even brief talk of Japan as a P.1216 customer....
And now I need to add a Japanese model to the whole rack of P1214s I'm planning on building. Yes, I know the production version was likely the P1216, but the lines of the P1214 are just so much better...
 
Props were not favoured as it was believed they could be detected at long ranges, maybe even subsurface from their inherent ULF.
That's correct, submarines can hear them beating on the water.
68hz tonal. I flinch into a "please don't hurt me" ball every time I hear one go overhead, courtesy of about 18 hours of constantly hearing them roar overhead and drop active sonobuoys on us that you could hear through the hull. At about the same frequencies as a dental drill...
 
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.
That design sounds to utterly weird to me. Very few planes are built that way, usually when the whole wing needs to be built in one piece for whatever reason. X-29's wing was one piece, so was Harrier II.

You’ve got to remember it’s where the De Havilland 106 Comet (Nimrod’s donner platform) had developed from. A mere ten years prior to the DH106 Comet being architected (ie the real fundamental design lay out) DH produced their first mono plane, the DH88 Comet and that used a tip to tip wing (pic attached). Roll on just five years, DH did the DH98 Mosquito again with a tip to tip wing. (Pic attached). Although these timescales look crazy in these enlightened times, the guys at DH had developed an expertise in tip to tip wing installed on a fuselage so naturally, used it. In the next pic you can see a Comet fuselage being lifted so the wing can be positioned under the Fuselage. (I have some pictures of an MRA4 that installation but can’t find them.) Interestingly that the both the later Comets and MRA4 wings were built with a transport joint at mid span, once made up, never to be disassembled . The next pic is from the MRA4 Type Record and shows the various links, struts etc used to secure the wing to the fuselage. This is in principle unchanged from the original DH106 Comet…. The whole MRA4 mantra was, “if it ain’t broke, don’t fix it” … While it worked in some respects, it also got us into a lot of trouble, particularly the aileron control cables… what was unknowingly “broken” was the ability engineer such a mechanical system when everyone with prior experience had retired.

The final picture is an MRA4 wing mid section being lifted into its pre fit holding jig. If that’s PA1, not sure but I maybe in that picture.
 

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I guess I should describe how a modern “computer designed and CNC machined ” wing is attached to the fuselage. This is typical in principle for all A, B, C and E team airliners. Well the Center wing torsion box is made integral to the fuselage frames. Two horizontal tongue flanges protrude from the fuselage top and bottom to match up with the top and bottom wing covers. The wing top and bottom covers overlap with these to from what’s sometimes referred to as a glove. The gap between these is filled by shim strips…. Yes shims…. And then hundreds of holes are drilled through this sandwich to allow the for it to be bolted together. Thus that’s now a uniquely matched assembly, absolutely no interchangeable . There’s no chance you ever remove a wing and fit it on another aircraft.
 

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That design sounds to utterly weird to me. Very few planes are built that way, usually when the whole wing needs to be built in one piece for whatever reason. X-29's wing was one piece, so was Harrier II.

You’ve got to remember it’s where the De Havilland 106 Comet (Nimrod’s donner platform) had developed from. A mere ten years prior to the DH106 Comet being architected (ie the real fundamental design lay out) DH produced their first mono plane, the DH88 Comet and that used a tip to tip wing (pic attached). Roll on just five years, DH did the DH98 Mosquito again with a tip to tip wing. (Pic attached). Although these timescales look crazy in these enlightened times, the guys at DH had developed an expertise in tip to tip wing installed on a fuselage so naturally, used it.
I keep forgetting just how "ancient" the Nimrod/Comet was...

In the next pic you can see a Comet fuselage being lifted so the wing can be positioned under the Fuselage. (I have some pictures of an MRA4 that installation but can’t find them.) Interestingly that the both the later Comets and MRA4 wings were built with a transport joint at mid span, once made up, never to be disassembled . The next pic is from the MRA4 Type Record and shows the various links, struts etc used to secure the wing to the fuselage. This is in principle unchanged from the original DH106 Comet…. The whole MRA4 mantra was, “if it ain’t broke, don’t fix it” … While it worked in some respects, it also got us into a lot of trouble, particularly the aileron control cables… what was unknowingly “broken” was the ability engineer such a mechanical system when everyone with prior experience had retired.

The final picture is an MRA4 wing mid section being lifted into its pre fit holding jig. If that’s PA1, not sure but I maybe in that picture.
If you were really lucky those engineers were still alive to call in as consultants...
 
it also got us into a lot of trouble, particularly the aileron control cables… what was unknowingly “broken” was the ability engineer such a mechanical system when everyone with prior experience had retired.


If you were really lucky those engineers were still alive to call in as consultants...

No, it was tried, even looked overseas, The last time a cable control system was designed from scratch in a large wing in the UK was at least 25years prior. Those skills and deep knowledge disappears really quickly and as pointed out before the devil is always in the detail.
 
If you were really lucky those engineers were still alive to call in as consultants...

No, it was tried, even looked overseas, The last time a cable control system was designed from scratch in a large wing in the UK was at least 25years prior. Those skills and deep knowledge disappears really quickly and as pointed out before the devil is always in the detail.
Sounds about right. And I bet the guys who designed that previous cable control system were senior engineers who started just after WW2...
 
9 - when PA1 flys (Aug 2004) it’s ailerons control forces are unacceptable, as is its yaw stability.
Do you know what they did about the lack of yaw stability?
 
Do you know what they did about the lack of yaw stability?

A yaw damper was integrated into the directional control system. (Specifically a “gurney flap” type device fitted to the rudder )
 
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