A alternative 1930s British tank gun - and its successor

[Tony Williams]

At the start of WW2 most British tanks were armed with the 2 pdr gun, which had a good armour penetrating performance for the day but very little HE potential. However, combat experience showed that tanks needed to fire HE more than AP. Would it have been possible, within the constraints of turret size and what was technically and financially feasible, to have made a better choice than the 2 pdr for arming tanks? And what might this have led on to?

My take on this is here: http://www.quarry.nildram.co.uk/alt%20WW2%20tank%20gun.htm Over to you, gentlemen!

 

[Rickshaw]

I've been thinking about this question you've raised. Surely the design and building of a gun which was designed around a larger calibre to facilitate HE use would have required a radical rethinking of the role of the tanks and artillery in British attack doctrine? Without cause for that to happen, why would it happen? Either there would need to be a visionary who could bring about such a change off his own bat or some event would need to cause a rethink. The former was lacking and I doubt from what we do know about British attitudes and thinking could have achieved it. The latter only occurred after encountering the enemy who showed a different way and even then, it took a few years for the lesson to be accepted.

 

[Tony Williams]

You are correct, of course. The biggest problem was the Royal Artillery, which insisted that only they could fire HE shells (or some such nonsense). The Tankers believe that the main gun was only for punching holes in enemy tanks, soft targets being engaged by the machine gun, but war experience (particularly with the M3 in the Western Desert) soon revealed the folly of this reasoning.

As a preliminary to introducing this proposal, you can add banging various senior officers over the head, hard and often, until they saw reason

 

[Sea Skimmer]

How about using the Belgian 60mm anti tank gun? Its not exactly small, but it was in service long before the outbreak of war and the British Army was willing to accept foreign weapons if they met its needs. It might also be adapted in artillery service in the same manner the French paired the small 25mm with the larger, more capable 47mm to defend artillery.


Thinking you didn't need HE shells made a lot more sense though, when all enemy anti tank guns were 37mm and actually effectively out ranged by machine guns themselves. The various short lived British close support tanks seem to have considered smoke shell firing to be more important than high explosive use.

 

[Tony Williams]

I don't know the dimensions of the Belgian 60mm cartridge. It would have to be fairly short (and therefore no great improvement on the 57x308R) to fit into the small turrets of late-1930s British tanks. Besides, the point of the proposal was to build on something already in British service.

As I understand it, smoke shells were mostly what the CS tanks were given to use. Which presumably accounts for their lack of success...

 

[Rickshaw]

You are correct, of course. The biggest problem was the Royal Artillery, which insisted that only they could fire HE shells (or some such nonsense). The Tankers believe that the main gun was only for punching holes in enemy tanks, soft targets being engaged by the machine gun, but war experience (particularly with the M3 in the Western Desert) soon revealed the folly of this reasoning.

Both attitudes were understandable considering the British Army's experience of WWI. Artillery was the king of the battlefield and while even at the time, it's dominance in thought and planning was criticised by, IIRC Ivor Maxse, it had proved though to be the main arm which had been innovative enough to facilitate the British advance. The tank was a useful adjunct but because of unreliability and lack of general availability wasn't the war winner that artillery was.

As a preliminary to introducing this proposal, you can add banging various senior officers over the head, hard and often, until they saw reason

I feel the British High Command is too often treated uncharitably by historians. They were trying to cope as best they could, in light of their training and knowledge. The real problem was the rigidity of the Regimental and Corps systems which stifled innovation in favour of tradition. Simply beating them over the head wouldn't be enough, what would be required would be a purge from about Major upwards or alternatively the arrival of a messiah who could completely revolutionise thinking and attitudes. Some defeats would have helped as well. Nothing like a defeat to create innovative thinking.

 

[Tony Williams]

I feel the British High Command is too often treated uncharitably by historians. They were trying to cope as best they could, in light of their training and knowledge. The real problem was the rigidity of the Regimental and Corps systems which stifled innovation in favour of tradition.

The problem is that the regimental tradition was (and still is) core to the army - the troops fight for their regiment, and often haven't performed anything like as well if they are separated from their regiments and just fight as a mixed bag of individuals. The trick is to turn the regiments in the direction you want them to go.

Simply beating them over the head wouldn't be enough, what would be required would be a purge from about Major upwards or alternatively the arrival of a messiah who could completely revolutionise thinking and attitudes.

We had them - notably Hobart (whose pre-WW2 writings were carefully studied in Germany). He was regarded by the establishment as rather odd.

Some defeats would have helped as well. Nothing like a defeat to create innovative thinking.

Absolutely. The German army in particular paid very careful attention to the lessons of WW1 and applied them logically. They were so much better than anyone else in 1940 that it was downright embarrassing - and it took the Allies a long time to catch up.

 

[Rickshaw]

I feel the British High Command is too often treated uncharitably by historians. They were trying to cope as best they could, in light of their training and knowledge. The real problem was the rigidity of the Regimental and Corps systems which stifled innovation in favour of tradition.

The problem is that the regimental tradition was (and still is) core to the army - the troops fight for their regiment, and often haven't performed anything like as well if they are separated from their regiments and just fight as a mixed bag of individuals. The trick is to turn the regiments in the direction you want them to go.

There is, I agree much to admire in the Regimental system but there is also much to criticise. It's rather incestous manner of only promoting from within its own ranks often stifled innovation and didn't necessarily result in the most able reaching the heights of command. Other nations have less rigid and hidebound systems which appear to motivate and inspire their members as well as the British regimental system.

Simply beating them over the head wouldn't be enough, what would be required would be a purge from about Major upwards or alternatively the arrival of a messiah who could completely revolutionise thinking and attitudes.

We had them - notably Hobart (whose pre-WW2 writings were carefully studied in Germany). He was regarded by the establishment as rather odd.

Well, he was odd. Many of the British innovators and commanders seem to have combined eccentricity with brilliance, which of course hasn't necessarily helped their causes. Also, their tendency to shuffle such embarrassing people off to obscure corners of Empire didn't help either. In particular, I've often wondered how Slim in particular would have done in Europe. Now, there was a quick learner!

Some defeats would have helped as well. Nothing like a defeat to create innovative thinking.

Absolutely. The German army in particular paid very careful attention to the lessons of WW1 and applied them logically. They were so much better than anyone else in 1940 that it was downright embarrassing - and it took the Allies a long time to catch up.

Some more than others. The Soviets were beating the Germans at their own game by 1944 when the Western Allies were still pretty much stumbling about.

 

[Grey Havoc]

Some more than others. The Soviets were beating the Germans at their own game by 1944 when the Western Allies were still pretty much stumbling about.

You could argue that was mostly due to the 'Soviet Hammer'. Even today, quantity used right is still a quality in itself.

 

[Rickshaw]

Some more than others. The Soviets were beating the Germans at their own game by 1944 when the Western Allies were still pretty much stumbling about.

You could argue that was mostly due to the 'Soviet Hammer'. Even today, quantity used right is still a quality in itself.

There was also a lot of manoeuvre involved as well. The Soviets lead in Operational Warfare in the Cold War didn't come from nothing.

 

[Grey Havoc]

True.

 

[Abraham Gubler]

You are correct, of course. The biggest problem was the Royal Artillery, which insisted that only they could fire HE shells (or some such nonsense). The Tankers believe that the main gun was only for punching holes in enemy tanks, soft targets being engaged by the machine gun, but war experience (particularly with the M3 in the Western Desert) soon revealed the folly of this reasoning.

Then maybe the solution to the problem has to come from an external agent. It might be easier to invent an alternate history scenario where the US or an Empire nation develops a pre-war tank and/or anti tank weapon with a HE capability. So maybe in place of the 37mm M3 the US Army adopted this Belgian 60mm gun? Then the M3 Stuart light tank and M3 Grant/Lee medium tanks would have 60mm guns and the later would be a single gun vehicle so no need for the M4 Sherman. It may not change the early generation of British tanks but the Churchill and Crusader would probably be built with the 60mm gun.

 

[Tony Williams]

Then maybe the solution to the problem has to come from an external agent. It might be easier to invent an alternate history scenario where the US or an Empire nation develops a pre-war tank and/or anti tank weapon with a HE capability. So maybe in place of the 37mm M3 the US Army adopted this Belgian 60mm gun? Then the M3 Stuart light tank and M3 Grant/Lee medium tanks would have 60mm guns and the later would be a single gun vehicle so no need for the M4 Sherman. It may not change the early generation of British tanks but the Churchill and Crusader would probably be built with the 60mm gun.

It would be simpler for the US to design a turret for the 75mm gun which was already in service as a field gun - in other words, going straight to the Sherman. It is highly unlikely that a high-velocity 60mm gun and ammunition would be any smaller than the medium-velocity 75mm - the British high-velocity 6 pr 7cwt (57mm) tank/antitank gun had ammo the same size as the 75mm and the guns were the same except for the bore diameter - so anything which could mount the 60mm could almost certainly mount the 75mm.

Which would still leave us with the first generations of British WW2 tanks having no general-purpose gun.

 

[Abraham Gubler]

Which would still leave us with the first generations of British WW2 tanks having no general-purpose gun.

Then look backwards and the Vickers medium tank and its 47mm gun (QF 3 Pounder) and at an apparent impediment: the power of the Royal Artillery. With the much heralded effectiveness of 37mm anti-tank guns in the Spanish Civil War have the RA demand they get all 2 Pounder production for anti-tank batteries. They were short of these guns by 1940 anyway. So tank production has to revert to the 47mm gun for the Cruiser Mk II and Matilda Mk II. The 47mm ordnance can be replaced by the 57mm coast artillery ordnance in later tank batches and then so on.

 

[Tony Williams]

Then look backwards and the Vickers medium tank and its 47mm gun (QF 3 Pounder) and at an apparent impediment: the power of the Royal Artillery. With the much heralded effectiveness of 37mm anti-tank guns in the Spanish Civil War have the RA demand they get all 2 Pounder production for anti-tank batteries. They were short of these guns by 1940 anyway. So tank production has to revert to the 47mm gun for the Cruiser Mk II and Matilda Mk II. The 47mm ordnance can be replaced by the 57mm coast artillery ordnance in later tank batches and then so on.

The 47mm was rather weak (built to 19th century standards) with only about half the penetration of the 2pr. And why bother, when the ammo was no shorter than the 6pr?

The 57mm coast artillery used ammo which was even longer than the AT/tank gun's. Not what you want to struggle with in a cramped tank turret.

 

[Rickshaw]

Perhaps if a larger round or calibre was adopted earlier, then the turrets would have been designed to accommodate it? It seems to me that you want a bigger/better gun but assume that it must be fitted into the turrets which were created for a smaller weapon. The smaller turrets were designed for the smaller weapon. So, if you adopt a larger weapon earlier (say the early-mid-1930s) then it would be safe that the tanks which were designed to mount it wouldn't necessarily be exactly as were designed and built in the real world.

At the same time you could postulate that the Royal Artillery wasn't as domineering in its attitudes towards the application of High Explosive, which would facilitate the adoption of such a gun. Although, its interesting that the Germans believed in the need for the majority of their tanks to carry a light gun which was primarily designed as an AT weapon and only a few as HE/Smoke throwers - a remarkably similar attitude to the Royal Tank Corps' in many ways.

 

[Tony Williams]

It's not just a question of designing different turrets - it would require a different approach to tank design, since the limitation was the diameter of the turret ring which had to fit within the hull. And if the hull was made wider, the tanks would no longer meet the army's requirement of being transportable intact by rail. I have accordingly taken the actual limits on tank and turret size as fixed, as far as this exercise is concerned.

Given the problems that the British had in getting even small and light tanks to work well, I hate to think of the delays which would have resulted from trying to jump straight to bigger tanks, even if the objections to them had been overridden.

 

[Rickshaw]

It's not just a question of designing different turrets - it would require a different approach to tank design, since the limitation was the diameter of the turret ring which had to fit within the hull. And if the hull was made wider, the tanks would no longer meet the army's requirement of being transportable intact by rail. I have accordingly taken the actual limits on tank and turret size as fixed, as far as this exercise is concerned.

As experience showed, the loading limits on the UK rail system weren't as restrictive as they were believed to be, how else were the Grants, Shermans, Cromwells, Comets, etc. moved around? I'm well aware of the limits that railway loadings place on armour design but if you're going to create new tank guns, then I'd suggest you may as well go whole hog and produce the tanks to mount them. This is a counter-factual discussion afterall.

Given the problems that the British had in getting even small and light tanks to work well, I hate to think of the delays which would have resulted from trying to jump straight to bigger tanks, even if the objections to them had been overridden.

Given that most of those problems were associated with the pressure designers and builders were under to field their tanks before they were fully developed, prewar tanks suffered from no such problems. The Vickers light tank series were mechanically reliable when maintained properly. Why else were the so successful on the export market? Give that your argument has had to be pushed further and further back in order to make it workeable, I think there would be sufficient time to perfect the design before the outbreak of war.

Of course, now we're getting to the point where the economics must be a consideration as it is entering the Great Depression.

 

[Tony Williams]

...if you're going to create new tank guns, then I'd suggest you may as well go whole hog and produce the tanks to mount them. This is a counter-factual discussion afterall.

Which means that you might as well go straight to making the Chieftain tank in the 1930s - there was little or nothing in it which couldn't have been made then.

The fact that a proposal is counter-factual doesn't mean that anything goes - the first requirement is to specify the parameters. In this case, I spelled out the parameters at the start of the article: "to see if something better than the 2 pdr tank gun could have been fielded at low cost in the run-up to WW2." No new tanks, no other conditions changed - just a better gun for the existing tanks. In such technological exercises, the political and doctrinal issues are separate - it is a simple exercise, with the benefit of hindsight, of the possibilities for one specific technical change.

 

[Rickshaw]

...if you're going to create new tank guns, then I'd suggest you may as well go whole hog and produce the tanks to mount them. This is a counter-factual discussion afterall.

Which means that you might as well go straight to making the Chieftain tank in the 1930s - there was little or nothing in it which couldn't have been made then.

Except of course there would be no need, nor could the armour, weapons, firecontrol systems, NBC protection system, optics or engine be produced because there was neither the metallurgy or industry supply train to build it. I do believe you might be able to produce the suspension though, as the Horstman system was available then, albeit in a different form. The tracks might be possible as well although the metallurgy might not be there yet, I suspect.

The point I am suggesting is that from little acorns, mighty oaks doth grow. You want to change one parameter yet that parameter has influence on so many others. A larger calibre gun requires a larger shell case. A larger shell case means that more space must be allocated to ammunition stowage. The size of the crew must be allowed for, so therefore the size of the turret must increase to accommodate them and this new ammunition, and of course there has to be some room for the bigger gun, so trying to defeat the 3 dimensional needs of everything doesn't seem possible to me, so a bigger turret and more than likely fighting compartment will be required to accommodate this larger turret will have to be taken into account, which in turn necessitates a bigger hull, which means a larger armoured volume so stronger suspension is required and a larger, more powerful engine and stronger gearbox and transmission, etc, etc.

Of course, this still does not address the reason why such a bigger gun would be needed. As you've acknowledged, British Army battle "ethos" (as the concept of "doctrine" had yet to appear and was actively resisted until the 1970s) would have to undergo significant change in order to actually create a demand for such a new weapon. Without that, no one would see the need and therefore there would be no demand so it would never occur.

You mentioned hindsight. Its a wonderful thing and I'd suggest the only vision that is perfect. I agree such exercises are enjoyable but unless you acknowledge that you can't shoe-horn a bigger gun into a tiny turret, then it will go no where simply 'cause there isn't room in the turret. If you need an example of that, look at what happened when the Israelis tried to put first a longer barrelled 75mm, then 105mm into a Sherman turret. In the end, there really wasn't all that much left of the turret, was there?

 

[Tony Williams]

Which means that you might as well go straight to making the Chieftain tank in the 1930s - there was little or nothing in it which couldn't have been made then.

Except of course there would be no need, nor could the armour, weapons, firecontrol systems, NBC protection system, optics or engine be produced because there was neither the metallurgy or industry supply train to build it.

Of course they could. They built large-calibre high-velocity guns in the 1930s, APDS was simply a matter of development, they had optical rangefinders and machine guns for ranging, they had thick armour (for warships), the engine was again a matter of development. The reason I mentioned the Chieftain is that it was arguably the last of the old-school technology tanks, before sophisticated armour, fire control and ammunition concepts came along. However, if the Chieftain is too much for you then compare the Centurion instead - that could most certainly be built using 1930s technology.

The point I am suggesting is that from little acorns, mighty oaks doth grow. You want to change one parameter yet that parameter has influence on so many others. A larger calibre gun requires a larger shell case. A larger shell case means that more space must be allocated to ammunition stowage. The size of the crew must be allowed for, so therefore the size of the turret must increase to accommodate them and this new ammunition, and of course there has to be some room for the bigger gun, so trying to defeat the 3 dimensional needs of everything doesn't seem possible to me, so a bigger turret and more than likely fighting compartment will be required to accommodate this larger turret will have to be taken into account, which in turn necessitates a bigger hull, which means a larger armoured volume so stronger suspension is required and a larger, more powerful engine and stronger gearbox and transmission, etc, etc.

Nonsense. I deliberately chose the 57x308R cartridge because it was the same length as the 2pr, therefore the gun chamber was the same length (and those two dimensions were the critical ones in determining whether or not a gun would be usable in any given turret). The extra width of the cartridge would reduce the ammo capacity to some extent, but that would be a small price to pay for the much greater effectiveness.

Of course, this still does not address the reason why such a bigger gun would be needed. As you've acknowledged, British Army battle "ethos" (as the concept of "doctrine" had yet to appear and was actively resisted until the 1970s) would have to undergo significant change in order to actually create a demand for such a new weapon. Without that, no one would see the need and therefore there would be no demand so it would never occur.

If that's the view you take, then I really don't know why you're bothering to contribute to alternative history threads, since they are all about providing answers to a wide range of "what if?" questions which, by definition, depart from what actually happened historically. All it would take in this case is someone in a position of influence to note that the army wanted close-support tanks to fire shells and other tanks with guns to penetrate armour, and to consider whether or not both needs might be met in the same tank with one gun.

You mentioned hindsight. Its a wonderful thing and I'd suggest the only vision that is perfect. I agree such exercises are enjoyable but unless you acknowledge that you can't shoe-horn a bigger gun into a tiny turret, then it will go no where simply 'cause there isn't room in the turret. If you need an example of that, look at what happened when the Israelis tried to put first a longer barrelled 75mm, then 105mm into a Sherman turret. In the end, there really wasn't all that much left of the turret, was there?

You seem to find it hard to grasp that the long-barrelled 75mm and the 105mm both had ammunition and gun breeches which were much longer than the medium-velocity 75mm which the Sherman was designed for. So did the Sherman Firefly, equipped with the 17 pdr. Yet despite this they did manage to squeeze the guns in. There would have been no such difficulties in fitting the short 6pr gun and ammo into turrets designed for the 2pr - that was the whole point of choosing it.

 

[robunos]

If you haven't already done so, may I suggest you peruse 'The Great Tank Scandal', by David Fletcher?
A lot of the points pertinent to this thread are covered there, for example :-

The only guns 'available' at the time able to fire a decent HE shell were a 3.7" breech loading mortar, and the 3" howitzer, neither of which could outrange the opposing anti-tank guns. (apart from the weapon you propose)

Tactical policy required the use of free elevation of the main tank gun, which in turn required it to be balanced precisely; this meant that the breech was mounted further to the rear within the turret, restricting the available space, also I would have thought that there is an upper limit to the size of gun that can be mounted this way.

The overall size of the tank, and thus the turret ring diameter, was restricted by the railway loading gauge, which was an apparently inviolate principle.

So my take on this is that the problem was mainly one of policy, rather than of technology...maybe if Vickers, when proposing the Valentine, had specified a better weapon, rather than the 'official' 2-pdr, that would have been the kick-start the process needed.

EDIT :- Just found a reference in 'The Great Tank Scandal' to a 1937 experimental A15 tank that would have been armed with both a 2-pdr and a 3" howitzer in the turret...

cheers,
Robin.

 

[Tony Williams]

If you haven't already done so, may I suggest you peruse 'The Great Tank Scandal', by David Fletcher?
A lot of the points pertinent to this thread are covered there, for example :-

The only guns 'available' at the time able to fire a decent HE shell were a 3.7" breech loading mortar, and the 3" howitzer, neither of which could outrange the opposing anti-tank guns. (apart from the weapon you propose)

Yes, I have had these excellent books (and several others by Fletcher) for many years, recommend them to anyone wanting to understand the development of British tanks in WW2, and referred to them in writing the historical introduction to the article which kicked off this thread.

Tactical policy required the use of free elevation of the main tank gun, which in turn required it to be balanced precisely; this meant that the breech was mounted further to the rear within the turret, restricting the available space, also I would have thought that there is an upper limit to the size of gun that can be mounted this way.

Correct. This was of a piece with the notion they had of how tanks would be deployed. With no experience of armoured warfare they took naval fleet actions as their guide, and thought that the tanks would cruise along in line ahead, firing on the move. So the guns had to able to be held steady by the gunner despite tank movement, and shoulder control was the best way of doing this. War experience rapidly showed that this was a daft idea (like RAF Fighter Command's tactics of deploying fighters in a tight "vic-3" formation - apparently just because it looked pretty - which meant that the two wingmen spent all of their time avoiding collision with the leader and had no time to look out for the enemy). The tankers were forced to drop this tactic when they upgunned to the much bigger 6pr HV anyway.

The overall size of the tank, and thus the turret ring diameter, was restricted by the railway loading gauge, which was an apparently inviolate principle.

Yep. That, indirectly, was what determined the size of the gun and ammo, as that was constrained by the turret size, which was constrained by the tank size.

So my take on this is that the problem was mainly one of policy, rather than of technology...maybe if Vickers, when proposing the Valentine, had specified a better weapon, rather than the 'official' 2-pdr, that would have been the kick-start the process needed.

Yes, that would have been one route. Vickers had export sales in mind, after all. With a new short 6pr developed and tested in a tank, it would have been rapidly available for production early in the war, even if the MoD hadn't ordered it beforehand.

EDIT :- Just found a reference in 'The Great Tank Scandal' to a 1937 experimental A15 tank that would have been armed with both a 2-pdr and a 3" howitzer in the turret...

That was possible because both guns had short breeches and used short ammo, so there was relatively little turret intrusion. As I've said, the constraint with tank guns and ammo wasn't width, but the length inside the turret.

Some of the later versions of tanks originally designed for the 2pr (Crusader and Valentine) were regunned with the 6pr high-velocity which had longer ammo than the short 6pr which I am proposing, but the space for this was so tight that only two men could be fitted into the turret. That meant they lost the loader, so the commander had to do the loading instead of commanding the tank, looking out for the enemy etc. That was tactically very undesirable, and wouldn't have been necessary with the short 6pr.

 

[robunos]

It would be simpler for the US to design a turret for the 75mm gun which was already in service as a field gun - in other words, going straight to the Sherman...

According to Hunnicutt's 'Sherman', this was the plan, following the realisation that the Medium Tank M2 & M2A1 were obsolete. However, such was the need for tanks, both from the USA and Great Britain, the decision was taken to produce the Medium M3, as it could be placed in production almost immediately...

"The major Weakness in the (M3's)design was the limited traverse of the hull mounted 75mm gun. However, Ordnance pointed out that no turret had yet been designed in this country to carry such a powerful weapon with full 360 degree traverse. On the other hand, many of the design problems in the sponson mount had already been worked out with the pack howitzer in the T5E2. Using this experience, such a mount could be put into production almost immediately. The Armored Force suggested that the M3s be limited to a small number such as 360 and full production be held up pending the design of a 75mm gun turret. However, the urgent need for large quantities of new tanks, particularly by the British in the Middle East would not permit the interruption of the production plans already in progress. Ordnance requested that full production of the M3 begin immediately. At the same lime, a new tank would be designed using the same basic chassis, but carrying a turret mounted 75rnrn gun. Because of its similar chassis, the new vehicle would replace the M3 on the assembly lines with only a small loss of production. This program was adopted and full production was approved without further delay....
In recommending the immediate production of the medium tank M3. the Ordnance Committee directed that work start as soon as possible on the design of an improved tank. Such a tank would correct the major flaws of the M3. but would be close enough in design to use many of the same major components. The new vehicle could then replace the M3 on the assembly line with a minimum loss of production. The Armored Force submitted detailed characteristics for the new medium tank on 31 August 1940. However. the design team assembled at Aberdeen was fully engaged during the Fall and Winter of 1940 completing the production drawings for the M3. When this job was finished on 1 February l941, a directive was received from the Chief of Ordnance to proceed immediately with the detailed design of the M3 replacement....
The turret was designed with a removable front plate permitting the installation of different armament combinations. Five basic arrangements were considered. These were (1) one 75mm gun M2 coaxial with one .30 caliber machine gun, (2) two 37mm guns M6 with one .30 caliber machine gun, (3) one 105mm howitzer with one .30caliber machine gun. (4) three .50 caliber machine guns mounted for high angle antiaircraft fire. and (5) one British 6 pounder high velocity gun coaxial with one .30 caliber machine gun."
(from the above source.)

cheers,
Robin.

 

[Sea Skimmer]

It's not just a question of designing different turrets - it would require a different approach to tank design, since the limitation was the diameter of the turret ring which had to fit within the hull. And if the hull was made wider, the tanks would no longer meet the army's requirement of being transportable intact by rail. I have accordingly taken the actual limits on tank and turret size as fixed, as far as this exercise is concerned.

It seems ironic that the limitation was applicable only to certain UK railroads, while the first mobile division was formed in Egypt. The French meanwhile had already proved road transport was entirely reasonable for fairly large tanks prewar, while I understand the limit, its worth considering that it may not have been as hard a problem as it first seems. It sounds a lot like a limit chosen for fiscal reasons, and not because rail transport within the UK was seen as militarily essential. After all, the TOG and that absurd 130 ton trenching machine were actually built in 1939-40. On the other hand the British Army was last in place for funding.

Given the problems that the British had in getting even small and light tanks to work well, I hate to think of the delays which would have resulted from trying to jump straight to bigger tanks, even if the objections to them had been overridden.

Very small designs had very tight margins though. Some persistent engine cooling problems for example might not have been as troublesome in larger designs and less emphasis might have been placed on troublesome raw speed.

 

[Tony Williams]

Five basic arrangements were considered. These were (1) one 75mm gun M2 coaxial with one .30 caliber machine gun, (2) two 37mm guns M6 with one .30 caliber machine gun, (3) one 105mm howitzer with one .30caliber machine gun. (4) three .50 caliber machine guns mounted for high angle antiaircraft fire. and (5) one British 6 pounder high velocity gun coaxial with one .30 caliber machine gun."
(from the above source.)

The US Army did of course adopt the British 6 pounder 7 cwt high velocity anti-tank gun (athough they called it the 57mm), which had significantly better armour penetration than the 75mm, so if hole-punching had taken priority the Sherman may indeed have seen service with the 57mm. The cartridge was pretty much the same size, so switching between the two was easy. The fact that it didn't happen was no doubt because the ability to fire a large HE shell was found to be so useful.

Here's a nice pic from the Ammo Photo Gallery on my website of German and British tank gun ammunition. The 6pr HV is the 57x441R, the 75mm US/British is the 75x350R.

37x249R (3,7 cm Pak / Kwk AP), 50x289R (5 cm L/42 Kwk Pzgr 40), 50x420R (5cm L/60 Pak 38, Kwk), 75x243R (7,5 cm L/24), 75x495R (7,5 cm L/43 and L/48: later Pz IV), 75x640R (7,5cm Kwk 42 L/70: Panther tank), 88x571R (8,8 cm L/56: Tiger 1), 88x822R (8,8cm L/71: Tiger 2).

47x376R (3 pdr Hotchkiss, similar to but slightly longer than 47x351R interwar tank), 40x304R (2 pdr AP), 57x441 (6 pdr APDS), 75x350R (US/British 75mm HE), 76x583R (17 pdr APDS), 76x420R (77mm mm in Comet tank), 76x134R (3" Howitzer for close-support tanks), 95x206R (95mm Howitzer for close-support tanks).

 

[Sea Skimmer]

It didn't happen because Army doctrine flat out said tanks don't fight tanks, the tank destroyer corps does, part of an elaborate plan to save manpower and yet provide a massed counter to massed enemy tanks. A 57mm half track mount for the tank destroyer corps was designed and a few produced, but never used because by the time it was ready it was mid 1942 and the weapon no longer met requirements. Some of the problems with the 76mm gun and ammunition have been attributed to the diversion of effort in 1941 to americanize the 6pdr and its ammunition as well, leading to a very small family of 57mm ammo as a side effect. If the US Army had wanted better tank killing tanks, it would have almost certainly tried to jump right to the 76mm gun, which it more or less correctly believed was powerful enough to destroy any tank in the world at the time of its design. As it was the time gap between 57mm production and 76mm production seems to be rather small in 1942, and before the invasion of North Africa.


The earliest 76mm tank destroyer prototypes actually directly adapted the 76mm anti aircraft gun in 1941, though the result was excessive profile. As far as I can tell the 57mm was never considered for a turreted vehicle.

 

[Rickshaw]

Which means that you might as well go straight to making the Chieftain tank in the 1930s - there was little or nothing in it which couldn't have been made then.

Except of course there would be no need, nor could the armour, weapons, firecontrol systems, NBC protection system, optics or engine be produced because there was neither the metallurgy or industry supply train to build it.

Of course they could. They built large-calibre high-velocity guns in the 1930s, APDS was simply a matter of development, they had optical rangefinders and machine guns for ranging, they had thick armour (for warships), the engine was again a matter of development. The reason I mentioned the Chieftain is that it was arguably the last of the old-school technology tanks, before sophisticated armour, fire control and ammunition concepts came along. However, if the Chieftain is too much for you then compare the Centurion instead - that could most certainly be built using 1930s technology.

However, it would not be a Chieftain tank, as we know it. It may look like a Chieftain but it would not perform as well as a Chieftain. Which is why I mentioned such things as metallurgy and the fire control. The Chieftain evolved because of reasons. It did not spring into being in a revolutionary manner from no where.

The point I am suggesting is that from little acorns, mighty oaks doth grow. You want to change one parameter yet that parameter has influence on so many others. A larger calibre gun requires a larger shell case. A larger shell case means that more space must be allocated to ammunition stowage. The size of the crew must be allowed for, so therefore the size of the turret must increase to accommodate them and this new ammunition, and of course there has to be some room for the bigger gun, so trying to defeat the 3 dimensional needs of everything doesn't seem possible to me, so a bigger turret and more than likely fighting compartment will be required to accommodate this larger turret will have to be taken into account, which in turn necessitates a bigger hull, which means a larger armoured volume so stronger suspension is required and a larger, more powerful engine and stronger gearbox and transmission, etc, etc.

Nonsense. I deliberately chose the 57x308R cartridge because it was the same length as the 2pr, therefore the gun chamber was the same length (and those two dimensions were the critical ones in determining whether or not a gun would be usable in any given turret).

However, I would suggest that you need to store those cartridges somewhere so the volume of each cartridge is important to the total size of the turret and hull because you need to keep them somewhere when they aren't in the use. Your choice allowed you to show-horn (perhaps) a larger calibre gun but I'd suggest as well a larger calibre gun has (usually) a larger recoil. The force can either be absorbed by a greater mass, a longer run out or larger recoil recuperators. All three require a larger volume within the turret. So, then you require more volume for the ammunition and the gun. As the volume for the crew remains a constant, that cannot be given away, now cannot it. As was shown with the evolution of the Valentine's turrets. Something has to give.

The extra width of the cartridge would reduce the ammo capacity to some extent, but that would be a small price to pay for the much greater effectiveness.

Would it? Armoured users tend to disagree.

Of course, this still does not address the reason why such a bigger gun would be needed. As you've acknowledged, British Army battle "ethos" (as the concept of "doctrine" had yet to appear and was actively resisted until the 1970s) would have to undergo significant change in order to actually create a demand for such a new weapon. Without that, no one would see the need and therefore there would be no demand so it would never occur.

If that's the view you take, then I really don't know why you're bothering to contribute to alternative history threads, since they are all about providing answers to a wide range of "what if?" questions which, by definition, depart from what actually happened historically. All it would take in this case is someone in a position of influence to note that the army wanted close-support tanks to fire shells and other tanks with guns to penetrate armour, and to consider whether or not both needs might be met in the same tank with one gun.

I am acting as "Devil's advocate". I am putting the hard questions which in such discussions are all too often glossed over because either the advocate hasn't considered them or doesn't want to consider them because they would demolish their counter-factual thesis.

You mentioned hindsight. Its a wonderful thing and I'd suggest the only vision that is perfect. I agree such exercises are enjoyable but unless you acknowledge that you can't shoe-horn a bigger gun into a tiny turret, then it will go no where simply 'cause there isn't room in the turret. If you need an example of that, look at what happened when the Israelis tried to put first a longer barrelled 75mm, then 105mm into a Sherman turret. In the end, there really wasn't all that much left of the turret, was there?

You seem to find it hard to grasp that the long-barrelled 75mm and the 105mm both had ammunition and gun breeches which were much longer than the medium-velocity 75mm which the Sherman was designed for. So did the Sherman Firefly, equipped with the 17 pdr. Yet despite this they did manage to squeeze the guns in. There would have been no such difficulties in fitting the short 6pr gun and ammo into turrets designed for the 2pr - that was the whole point of choosing it.

I am well aware of the reasons why the Israeli had to butcher the turrets of their Shermans to shoe-horn in a larger calibre gun, however, what you don't seem to appreciate is that ultimate it was because the turret was simply too small to fit a larger gun. The length of breech and recoil was one factor, there were others, such as ammunition stowage, other equipment (such as radios) and of course, the poor squashed and all too often forgotten crew.

As I've pointed out above, some points have either been ignored because they are convenient or because they are not, at least in my opinion understood properly by yourself. I acknowledge that you have a great deal of expertise in the field of firearms but not so much in the actual history of tank development.

At the moment we have your proposal of "what if we changed the gun in British tanks from a 2 pdr?"

To which I have pointed out the following questions need to be answered:

* Why would it occur? What reason would make such a change happen.
* What change to doctrine would be required to create a demand for this change?
* When would such a change be necessary in order to come to fruitition by the date you desire?
* What effect would it have on tank design as a whole? You simply cannot change the gun without other attendant changes occurring as well.


I feel you're putting the cart before the horse to a degree. You want something to change without recognising that change would not occur without a reason. That reason would have to be either circumstance or personality and from that would flow changes in thinking and hence demand which would then see a change in the gun.

 

[robunos]

The turret was designed with a removable front plate permitting the installation of different armament combinations. Five basic arrangements were considered. These were (1) one 75mm gun M2 coaxial with one .30 caliber machine gun, (2) two 37mm guns M6 with one .30 caliber machine gun, (3) one 105mm howitzer with one .30caliber machine gun. (4) three .50 caliber machine guns mounted for high angle antiaircraft fire. and (5) one British 6 pounder high velocity gun coaxial with one .30 caliber machine gun."

My take on this is that someone, either on the British or US side, was anticipating that the M4s supplied to the British Army would be equipped with the 6-pdr. The fact that Hunnicutt specifically refers to the 6-pdr, rather than the 57mm, leads me to think that the weapon referred to is the British weapon...
A query on the origin of the M3 and M4's 75mm gun. Tony Williams refers to it as a version of the in-service 75mm field gun, whereas Hunnicutt states that the tank weapon was developed 'from an unsuccessful low-velocity anti-aircraft weapon'. Can anyone add to this?

cheers,
Robin.

 

[Tony Williams]

The point I am suggesting is that from little acorns, mighty oaks doth grow. You want to change one parameter yet that parameter has influence on so many others. A larger calibre gun requires a larger shell case. A larger shell case means that more space must be allocated to ammunition stowage. The size of the crew must be allowed for, so therefore the size of the turret must increase to accommodate them and this new ammunition, and of course there has to be some room for the bigger gun, so trying to defeat the 3 dimensional needs of everything doesn't seem possible to me, so a bigger turret and more than likely fighting compartment will be required to accommodate this larger turret will have to be taken into account, which in turn necessitates a bigger hull, which means a larger armoured volume so stronger suspension is required and a larger, more powerful engine and stronger gearbox and transmission, etc, etc....

If you were correct, it would have been impossible to fit the 3 inch howitzer in the turrets designed for the 2pdr, because the cartridge was much wider and developed more recoil. In fact, this was done without any need to compromise on the crew numbers.

The 6pr 7cwt HV fitted to the later Valentine and Crusader tanks had a cartridge case 133mm longer than the short 6pr in my proposal. Which meant the gun chamber was that much longer too. So you are looking at double that extra distance required to be able to place a round behind the gun breech and then load it: 266mm extra length to be accommodated within the turret. According to your theory, the turret ring would have had to have been that much wider in diameter to accommodate the 6pr HV. And of course the ammunition was a lot more powerful and developed a lot more recoil. Yet even so the 6pr HV was fitted in, at the cost of a crew member.

Would it? Armoured users tend to disagree.

Which armoured users would that be? The ones who were grateful to have Valentine and Crusader tanks with 6pr rather than 2pr guns, despite the much reduced ammo storage and the loss of a crew member? I'd be interested in knowing a source for your claim.

Of course, this still does not address the reason why such a bigger gun would be needed. As you've acknowledged, British Army battle "ethos" (as the concept of "doctrine" had yet to appear and was actively resisted until the 1970s) would have to undergo significant change in order to actually create a demand for such a new weapon. Without that, no one would see the need and therefore there would be no demand so it would never occur.

Had my "what if?" been concerned with exploring the circumstances which might have caused the British Army to consider a combined HE and AP gun, your criticism would be valid. As my "what if?" is solely concerned with exploring the technical issues around whether that would have been practically feasible, it is not.

I am acting as "Devil's advocate". I am putting the hard questions which in such discussions are all too often glossed over because either the advocate hasn't considered them or doesn't want to consider them because they would demolish their counter-factual thesis.

What you are doing is posing a different question to the one I asked, and are then complaining that my proposal doesn't contain the answer to your question. Well, tough - it's not meant to.

 

[Tony Williams]

A query on the origin of the M3 and M4's 75mm gun. Tony Williams refers to it as a version of the in-service 75mm field gun, whereas Hunnicutt states that the tank weapon was developed 'from an unsuccessful low-velocity anti-aircraft weapon'. Can anyone add to this?

The gun was a new design, but it was designed around the 75x350R ammunition which had been in US Army service since the famous French "75" field gun was bought by the US in WW1. So the ammo design dated back to the 19th century, although of course new and more effective loadings were developed by WW2.

 

[robunos]

Thanks for the clarification...

cheers,
Robin.

 

[PMN1]

The overall size of the tank, and thus the turret ring diameter, was restricted by the railway loading gauge, which was an apparently inviolate principle.

I've quite often seen a statement that US, German and Soviet tanks supported their turrets on a superstructiure which to a degree overhung the tracks while the UK went for a turret ring within the track base for greater stability on the battlefield.

How true is this?

 

[Tony Williams]

I understand that British tanks did keep their turret rings within the hull width while some other designs did not, but I'm not sure exactly why.

 

[Spark]

Hi Tony,
Turret cannon in sponsons either side of turret? Would this ease the problem and given extra room?

I understand that British tanks did keep their turret rings within the hull width while some other designs did not, but I'm not sure exactly why.