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#101 Stuart Galbraith

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Posted 09 May 2020 - 1204 PM

Well, show me a HE Frag that can be fired through an L30 and Ill be happy to lobby my local MP to that end. :)


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#102 Interlinked

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Posted 09 May 2020 - 1315 PM

That has nothing to do with the discussion.

 

But if you have a rifled gun, there isnt much point not having it

 

HESH has been used for decades due to institutional inertia. Basically the same reason why L30 itself was chosen for Challenger 2 instead of something better (and non-compatible with stockpiled 120mm ammo). Now that the L30 is finally going to be replaced with a smoothbore, it will have a new and better range of ammo available, including modern HE-Frag.


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#103 Stuart Galbraith

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Posted 09 May 2020 - 1326 PM

No, the reason why L30 was chosen was because it was going to be fitted to Challenger 1 and Chieftain. It had nothing to do with institutional inertia, and a lot to do with a large stockpile of HESH rounds. It made perfect sense at the time, in 1989 when they started design work on challenger 2. By the time it entered service in 1996 it clearly didnt make much sense at all because they had all gone.

 

Look, im not trying to hijack the discussion into a discussion of Challenger 2. Im just illustrating, the reasons for why its lasted so long are quite broad, and go right back to the cold war. From what ive read it did prove highly useful in Basra. yes, undoubtedly other rounds would have done the job as well if not better. But you work with what you have.


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#104 Interlinked

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Posted 09 May 2020 - 1331 PM

I'm not sure what you read in my post, but... That's exactly what I said?
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#105 Ssnake

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Posted 09 May 2020 - 1702 PM

I think the decision to arm the Challenger 1 with the L30 gun was largely driven by two factors,

a. hoping that it would be the new standard gun for NATO tanks like the L7 before

b. because of the stockpile of compatible HESH and HEAT rounds that had been procured for the Conqueror first, and then the Chieftain which the Challenger was supposed to replace

 

I think that b. was a stronger motivation than a., but that's pure speculation on my part.


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#106 Interlinked

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Posted 09 May 2020 - 2350 PM

a. IIRC, the 120x570mm round of the Rh120 was already a NATO standard by the time work on the successor to the Challenger started.

b. Ammo for the Conqueror's L1 gun was not compatible with the L11 and L30. Also, British never procured HEAT.
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#107 Stuart Galbraith

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Posted 10 May 2020 - 0136 AM

Yeah, Conqueror ammunition was completely unrelated to ammunition to the L11. The L1 inspired the L11 but that was about it.

 

The gestation for L30 goes back to the 1970's. Back then we were tooling around with a 110mm gun (A smoothbore unless im misremembering badly) we were hoping would be NATO standard. When the Americans drifted away to the Germans (and put of procuring the 120mm for some of the same reasons we put off getting a smoothbore interestingly, namely a big stockpile of ammunition) we decided to moved towards a 120mm weapon firing a higher charge. That became XL32 and later developed into XL30 IIRC. By the time we decided to procure Challenger 2 there was absolutely no hope of getting a NATO contract. It was purely to retrofit into Chieftain and Challenger 1 which we were keeping in service. And then the world changed and it didnt look such a good idea anymore, but look at it from Vickers point of view. If they had waited to redesign Challenger 2 for a 120mm smoothbore (which they could have done given time) the window for selling Challenger 2 would have closed, and they would have had an expensive irrelevance on their hands. So they gave it to the MOD, they liked it, and they sold 386 units. Far more than they were expecting, because Challenger 1 was to be upgraded, not replaced.

 

It all looked a good idea at the time, the timing was bad was all. I dont think it would have made much difference to exports though, Challenger 2 was always going to be squeezed out the market place by cut price Leopard 2's  with one careful owner. 5 years earlier? Maybe different.

 

We never procured HEAT, but Bob Griffin convinced me we did develop it for the L11 to fulfill an Iranian contract. There was also a flechette and illumination round. No idea if any of them were delivered though.


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#108 methos

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Posted 10 May 2020 - 0330 AM

The L30 was also chosen as main armament of the Challenger 2, because there wasn't any other viable option available for Challenger 2. It was designed by Vickers, not by the British FVRDE and thus had to rely on technology available to Vickers.

 

As the UK had turned down the technology transfer of Rheinmetall's smoothbore gun during the 1970s (which was offered by the Federal Republic of Germany free of charge if the MBT 80 was to be fitted with it), the L30 was the best option available. Soviet-made 125 mm smoothbore guns were obviously a no-go for political reasons, while both GIAT and Rheinmetall (as sub-contractor of Krauss-Maffei) were actively competing in the Chieftain replacement program against Vickers - thus it seems rather likely that their smoothbore guns weren't available for Vickers. The same applies to the M256, though here the question also needs to be asked, if the M256 could have been sold to Vickers at all depending on the exact license/technology transfer agreement between the FRG and the US.

 

Various different gun concepts were considered during the MBT 80 program, including the EXP24 MI and EXP3M5. None of which had been a smoothbore - the 110 mm guns were all rifled. The British military believed that APFSDS could not provide the desired accuracy based on early experiences when fin-stabilization still had its quirks.


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#109 Ssnake

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Posted 10 May 2020 - 0352 AM

The same applies to the M256, though here the question also needs to be asked, if the M256 could have been sold to Vickers

 

No.

That Israel "invented" its "own" 120mm smoothbore cannon shortly after the M256 was licensed to the US is still a sour point with Rheinmetall.


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#110 Interlinked

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Posted 10 May 2020 - 0428 AM

Yes. So in other words, the choice of the L30 is ultimately due to institutional inertia. 


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#111 Stuart Galbraith

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Posted 10 May 2020 - 0431 AM

The L30 was also chosen as main armament of the Challenger 2, because there wasn't any other viable option available for Challenger 2. It was designed by Vickers, not by the British FVRDE and thus had to rely on technology available to Vickers.

 

As the UK had turned down the technology transfer of Rheinmetall's smoothbore gun during the 1970s (which was offered by the Federal Republic of Germany free of charge if the MBT 80 was to be fitted with it), the L30 was the best option available. Soviet-made 125 mm smoothbore guns were obviously a no-go for political reasons, while both GIAT and Rheinmetall (as sub-contractor of Krauss-Maffei) were actively competing in the Chieftain replacement program against Vickers - thus it seems rather likely that their smoothbore guns weren't available for Vickers. The same applies to the M256, though here the question also needs to be asked, if the M256 could have been sold to Vickers at all depending on the exact license/technology transfer agreement between the FRG and the US.

 

Various different gun concepts were considered during the MBT 80 program, including the EXP24 MI and EXP3M5. None of which had been a smoothbore - the 110 mm guns were all rifled. The British military believed that APFSDS could not provide the desired accuracy based on early experiences when fin-stabilization still had its quirks.

The problem is, Im not sure its actually true. The design forebear for Challenger 2's turret, the Vickers Mk7 MBT (and before that, Vickers Valiant) actually had the stated ability (not admittedly trialed) to mount a 120mm smoothbore gun. It was offered as an option. If they had been told by the MOD Challenger2  had to have a smootbore, that work still waited in the wings. Ok, so it would have taken extra work, some modification of internal stowage, but it could I think have been done.The MOD just didnt ask for it is all.

 

Im not sure they absolutely had to rely on their own equipment. We saw that they could do a turret for Leopard2. They actually did a bridgelayer design for the South Korean K1. None of that needed FVRDE involvement to happen as far as Im aware.

 

The Israelis got the 120mm from the US without any such niceities as Nils points out.

 

Have you got a source for that 120mm gun offer, im fully willing to believe it, ive just not seen it. Once again though, this would have been no good for Chieftain, which as we saw they intended to keep it in service.

 

Thanks for that on the 110mm, im clearly misremembering.


Edited by Stuart Galbraith, 10 May 2020 - 0432 AM.

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#112 Old ROF

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Posted 11 May 2020 - 0752 AM

Yeah, Conqueror ammunition was completely unrelated to ammunition to the L11. The L1 inspired the L11 but that was about it.
 
The gestation for L30 goes back to the 1970's. ..we decided to moved towards a 120mm weapon firing a high charge. That became XL32 and later developed into XL30 IIRC. By the time we decided to procure Challenger 2 there was absolutely no hope of getting a NATO contract. ...
 
We never procured HEAT, but Bob Griffin convinced me we did develop it for the L11 to fulfill an Iranian contract. There was also a flechette and illumination round. No idea if any of them were delivered though.

During development the designation of the CHARM gun as the 120mm became was the EXP32M1, M2 etc depending on the variant. This became XL30 in official MOD nomenclature following their numbering system, and L30 once in service.

Can confirm there was a HEAT round being developed for Chieftain. Was displayed at BAEE one year, mid-late seventies and reported by Jane's. (image attached) I remember seeing an example at RMCS in 1979.

Edit to add images.

Attached Files


Edited by Old ROF, 11 May 2020 - 0942 AM.

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#113 Stuart Galbraith

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Posted 11 May 2020 - 0815 AM

There is a nice photo of the breech end of an EXP32 (thanks for correcting that) in the Haynes book on Challenger 2, in the turret of 'MBT80' at Bovington. Thanks for clearing that up.

 

Did they do anything exotic with the HEAT round? I remember from Kenneth Macksey's Tank vs Tank that at least one nation did a counter rotating heat round for firing through a rifle, I was just idly wondering if it was this.


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#114 bojan

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Posted 11 May 2020 - 0913 AM

Soviet 76/85/100/122mm HEAT were counter-rotating with a copper slip ring and fins canted to slow initial rotation. US 90/105mm HEAT was also. Also clones of those.

French did overly complicated 90/105mm HEAT with ball bearings.


Edited by bojan, 11 May 2020 - 0914 AM.

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#115 Stefan Kotsch

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Posted 11 May 2020 - 0928 AM

Counter-rotation is probably an exaggeration.  The HEAT, because of its greater moment of inertia, rotates acceptably slower than the slip ring.


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#116 Interlinked

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Posted 11 May 2020 - 0942 AM

Yeah, I'm pretty sure the fins were all perfectly straight.
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#117 Stefan Kotsch

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Posted 11 May 2020 - 0951 AM

... and fins canted to slow initial rotation. ..

At least with the 125 mm HE-FRAG and HEAT ammunition, the fins are slightly canted on the front.  And even the 125 mm BM9/12 had this canting fins for a small initial rotation - probably for a better detachment of the sabot . But, with the 100 mm HEAT my memory is not good enough.


Edited by Stefan Kotsch, 11 May 2020 - 0952 AM.

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#118 Przezdzieblo

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Posted 11 May 2020 - 1324 PM

There was a HEAT round for UK 120 mm EXP-19M13A gun, described from being unsuccessful to being a failure. Probably one sample survived in Bovington, on display with UK gun tubes.

 

 

Attached Files


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#119 bojan

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Posted 11 May 2020 - 1454 PM

Counter-rotation is probably an exaggeration.  The HEAT, because of its greater moment of inertia, rotates acceptably slower than the slip ring.

Well, there is no real counter-rotating projectile that changes it's rotation, but it is a term often used to describe HEAT with something (slip ring, ball bearings, whatever) that prevents it from reaching full rotation speed.

Interesting tidbit - Yugoslavia made 76mm HEAT in two versions - first one for ZiS-3/D-56 gun on PT-76, and other for M1/M1A1 guns on Sherman and M18 Hellcat. Only difference in the projectile was that on first one slip ring was soldered on and on firing angular acceleration broke solder joint, while on the second one it was free to rotate - due the progressive rifling of M1/M1A1 guns they did not produce enough of the momentum to free soldered one.


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#120 Stuart Galbraith

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Posted 13 May 2020 - 1146 AM

Soviet 76/85/100/122mm HEAT were counter-rotating with a copper slip ring and fins canted to slow initial rotation. US 90/105mm HEAT was also. Also clones of those.

French did overly complicated 90/105mm HEAT with ball bearings.

Thats probably the one im thinking of then,  thanks for that.


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