British 1936-42 purchase options, logistics and export/import of military hardware (1 Viewer)

[Elan Vital]

I forgot to discuss it as well, but another peculiarity of the whole Crusader ordeal was that between the rushed production at home with overburdened quality control (Beaverbrook "I want all the tanks"), improper handling for shipment, and then the inherently low durability of the Crusader in NA...the bulk of the repair capacity in NA was completely clogged up by almost entirely Crusaders.

In hindsight the British could probably have reduced production rate a bit to focus on quality and sent less tanks in that theater, but would still have ended up with much the same quantity of operational tanks, except that REME would be less overloaded.

 

[EwenS]

What seems to be getting lost in this discussion is the timeline for the development of the various tanks

Infantry Tanks
A11 Matilda I - Oct 1935 Sir John Carden, chief tank designer at Vickers-Armstrong attended a meeting at the War Office and left with a draft proposal for a small two man tank armed with a single MG. The new design had to be ready in 6 months and be cheap. Prototype was ready for testing by Sept 1936. Problems were then ironed out and orders for two batches of 60 each placed with VA in April / May 1938 with a final batch of 19 in Jan 1939. Of the 140 built, 77 were lost in France in the lead up to the Dunkirk evacuation.

A12 Matilda Senior or Matilda II - First proposal by the War Office in Sept 1936 for enlarged infantry tank with emphasis on greater power and speed and a 3 man crew rather than better firepower or protection. Then 3 months haggling over engine and a contractor to build the new design, leading to Vulcan Foundry being chosen (better known for railway engine production). £30k funding included in the 1937 Army Estimates for two prototypes. And so the design evolved with thicker armour 3 man turret with 2pdr (because the official view was that these tanks were there to protect infantry against enemy tanks). Some did advocate a weapon firing HE. Armour plate thicknesses ranged from 20mm to 78mm. Production of the front hull nose casting proved to be a bottleneck with castings requiring much finishing.

Prototype ready for test in April 1938. Initial order to Vulcan Foundry in June 1938 and then 40 from Ruston & Hornsby in Aug 1938. Other manufacturers came on board as war loomed with some having greater problems than others in starting up production. Last order, for 75, was issued in March 1942, which was not completely fulfilled until 1943. Very few were in service by the outbreak of WW2 with production running at 7 per month. Only 23 were shipped to France for the use of the BEF (7th RTR) where all were lost.

Valentine - Design of the Valentine began as a private venture by Vickers Armstrong, using the experience they had gained in the designs of the A9/10 & A11 tanks. They sought to produce a compact infantry tank with a crew of 3 which could carry a good weight of armour and possess a high degree of reliability. In pursuing this route they had one eye on the export matket which tended to favour small tanks.

VA preferred to build its own tank design rather than pursue the offer of building A12 Matilda, as it suited their production processes and they believed they could start production quicker than having to retool to build the latter.

VA first showed their design to the War Office on 10 Feb 1938, before the prototype A12 Matilda was ready for testing. By then they had weighted up an A10 chassis to the 16 tons a Valentine was expected to weigh with most of its armour at 60mm. Yes it had a two man turret, but the gun they proposed was their own automatic 40mm design, capable of using the same ammunition as the new WO 2pdr. That way they could do away with the loader and make a two man turret a viable proposition. VA also believed that it would be cheaper than the A12 and could enter production as soon as March 1939. A revised vehicle was offered in March 1938. The WO rejected the design as they wanted a 3 man turret, cupola, their own 2pdr gun and a No 11 wireless set. And so the project died - temporarily. But it seems VA continued work on the design during the course of the next year.

Turn the clock forward to April 1939, and the WO resusitated the Valentine design on the basis that they needed tanks, any tanks, ASAP. The WO were now prepared to accept a two man turret (although by then a three man turret was presented in a new mockup but how this was done is lost to time) if really rapid production could be assured. More modifications were requested before a production orders for 400 were granted to 3 companies at the end of June / beginning of July 1939. The first production Valentine I was delivered for trials in April 1940. First deliveries of Valentine I to operational units began in June 1940.

Later, in 1941, a new 3 man turret was designed for the Valentine III/IV/V.

Then came the 6pdr versions which reverted to a two man turret design to accomodate the larger gun. This was based on the 3 man turret with a modified front. But the extra recoil prevented a third man being in the turret. Dick Taylor in "Into the Vally" noted the following (with my emphasis) "...the RAC had long realised - as early as 1940 - that the 6 Pounder would be needed as a tank gun, but fears that the introduction would cause a massive drop in production led to the 2 Pounder being retained longer than was operationally desireable. When the decision was finally taken to put the larger gun into tanks, there were only three service tanks capable of taking the gun and mounting. These were the Churchill, Crusader and Valentine. In both the latter cases the small size of the turret ring meant that only a two-man turret crew could be accomodated." The Valentine turret ring was only 50in internal diameter.


A13 Mk.III Cruiser V Covenanter - Designed from Feb 1939 as something intended to be lighter & cheaper than the A15 Crusader. As intended it incorporated a new suspension system, a new engine, new transmission and its hull would be welded (a first for a British tank). Ordered off the drawing board on 17 April 1939. Then the WO wanted thicker armour, while welding was found to be impracticable in part due to a shortage of trained welders, aluminium roadwheels had to be replaced with steel (aircraft industry had priority for the former) and the old gearbox substituted. All of which added weight. First pilot delivered for trials in May 1940.

A15 Cruiser Mk.VI Crusader - developed by Nuffield alongside the Covenanter, but starting a bit later, powered by V12 Liberty engine as used in the earlier A13 cruiser models built by that company. Prototype sent for testing on 9 April 1940.

Development of the 6pdr
This began at the Woolwich Arsenal in 1938, with a pilot gun manufactured and tested in 1939. The design was then put away until the day when it would be required, the 2pdr being more than adequate to deal with opposing tanks during this period.

The BEF lost 509 2pdr AT and 88 Hotchkiss 25mm AT guns in France in June 1940, leaving the Army with just 333 2pdr. The choice was continuing production of the 2pdr at a rate of 83+ per month (up from 47 in Sept 1939), a weapon that the Army was already familiar with, or accepting a reduction in production levels while retooling for the 6pdr took place. It was estimated that production of 100 6pdrs would displace 600 2pdr.

So looking at the various tank designs you get down to the Churchill and Cavalier / Centaur / Cromwell families before the 6pdr was available to consider as a potential tank weapon.

 

[Shortround6]

The Crusader was plagued with host of relatively minor problems, some of which Elan Vital has outlined.
A major problem in Africa was the air filters which then affected other parts of the engine/drive train.
There were changes in both filter type and location.
The other main problem was the cooling fan assembley and water pump. As mentioned early, this was a self inflicted wound. Granted they didn't have the number of Cruiser A13s in service but a lot of what they had learned on the A 13s didn't apply to the A-15s with their shallower engine compartment and the dual fan set up.

And some of this goes back to trying to develop too many different tanks at the same time.
There was a lot finger pointing going on even in 1942 over these two problems.
For some reason they thought that putting the air-filters on top of the rear track fenders was a good idea (maximum area for dust/dirt).
Now at times during this they had people trying to fix the cooling on the Covenanter 3 times but even the Covenanter IV wasn't good enough to see service.

 

[MikeMeech]

Hi
On the subject of British Tank design, production and use in the inter-war and WW2 period, at least there is no shortage of books to read. These include David Fletcher's 'trilogy' on the subject from The Tank Museum:
'Mechanised Force - British Tanks between the Wars'
'The Great Tank Scandal - British Armour in the Second World War Part 1'
'The Universal Tank - British Armour in the Second World War Part 2'

Also Dick Taylor's books:
'Armoured Warfare in the British Army 1914-1939'
'Armoured Warfare in the British Army 1939-1945'
'The Second World War Tank Crisis - The Fall & Rise of British Armour 1919-1945'

There is also the final chapters in both 'Men, ideas and tanks- British military thought and armoured forces, 1903-1939' by J.P. Harris and 'A New Excalibur - The Development of the Tank 1909-1939' by A.J. Smithers, and probably many others over the years.

Mike

 

[z42]

And some of this goes back to trying to develop too many different tanks at the same time.
There was a lot finger pointing going on even in 1942 over these two problems.

Hi
On the subject of British Tank design, production and use in the inter-war and WW2 period, at least there is no shortage of books to read. These include David Fletcher's 'trilogy' on the subject from The Tank Museum:
'Mechanised Force - British Tanks between the Wars'
'The Great Tank Scandal - British Armour in the Second World War Part 1'
'The Universal Tank - British Armour in the Second World War Part 2'

The title of the final book maybe points to the solution of the problem of too many different tanks? I wonder, how much if any knowledge did the Western Allies have of the Soviet developments? I would suspect generally little, even after they became allies subsequent to the Barbarossa invasion? The Soviets were perhaps pioneers in the widespread adoption of the universal tank concept, in that following their experiences fighting Japan in the late 1930'ies (Khalkin Gol etc.) they embarked on developing a heavily armored medium tank equipped with a gun big enough to also have a useful HE capability, which eventually resulted in the T-34.

If Britain were to stumble upon the same concept earlier, seems the critical thing would be getting something like the QF 75mm into use sooner, rather than the 6pdr. Though if we want the QF 75mm earlier, then maybe it's not realistic to assume one can piggyback on the American M2/M3/etc. work and use their 75mm shell. Maybe the WWI era 13pdr shell would roughly have been a usable starting point? Maybe not the 13-pounder gun itself, being wire wound it was perhaps not suitable to economic high volume manufacturing in the WWII era?

 

[z42]

Since this and several other threads have touched on the topic of tank suspensions, and (some?) people seem to hold strong opinions on that, I made a separate thread for discussing them at Tank suspensions; fight! .

 

[tomo pauk]

If Britain were to stumble upon the same concept earlier, seems the critical thing would be getting something like the QF 75mm into use sooner, rather than the 6pdr. Though if we want the QF 75mm earlier, then maybe it's not realistic to assume one can piggyback on the American M2/M3/etc. work and use their 75mm shell. Maybe the WWI era 13pdr shell would roughly have been a usable starting point? Maybe not the 13-pounder gun itself, being wire wound it was perhaps not suitable to economic high volume manufacturing in the WWII era?

Either the 12pdr 12cwt, or and indeed the 13pdr 9cwt can be the starting point.
The less the hot water need to be re-invented, the better.

 

[ThomasP]

re the 'best' gun size for the late-1930s British gun tank

The US adopted the French 75mm Gun Model 1897 in the early 1900s. During WWI the US manufactured the 75mm Gun Model 1917, which was actually a British 18pdr Gun of the WWI period, with the barrel relined to use the French 75mm ammunition and with an Asbury Breech mechanism fitted. Ballistic performance was about the same as the US 75mm Gun M2 as fitted in the M3 Lee/Grant tanks, with a MV of 1900 ft/sec when firing a 12.3 lb projectile.

Since the weight of the barrel and breech mechanism was about 995 lbs, the gun could be considered a '12pdr 9cwt' or '75mm 9cwt' in British terms. The weight of the barrel and breech of the French 75mm Gun model 1897 was about 1050 lbs, and weights of the US 75mm Gun M2 and M3 about 800 lbs and 900 lbs respectively, so the basic weight of the 75mm Gun Model 1917 would not be too different.

At the end of WWI the British tested their 18pdr Gun with a horizontal sliding block mechanism, but did not adopt it at the time (I have no idea why). I do not see any reason why this could not have been accomplished by the early- to mid-1930s.

Given all of the above, it seems to me that the British could have done similar to the US and either adopted the 75mm/18pdr gun, or produced a 3"/76.2mm version, or possibly even kept the 84mm/18pdr ammunition capability. In each of these cases they would have had a useful AP, HE, SMK, Shrapnell, etc, capability at the start of the war, with large and readily available ammunition stocks.

Obviously, as has been pointed out upthread, the tank turret size would have to be kept at the minimum of the Vickers Medium (Ø?" turret ring) and Cruisers Mk I, Mk II, and Mk III (all with Ø54.5" turret rings) at least. I am using this turret size and turret ring diameter as a minimum since they could all carry the 3.7"(94mm) Tank Mortar.

Incidentally, the Valentine had a [ Ø50.0" ] turret ring.

PS If anyone has run across an authoritative source for the diameter of the Vickers Medium turret ring please let me know.

edit: In addition, the 18pdr Gun Mk IV (which entered service in 1921) had a barrel and breech that weighed 859 lbs, so maybe an 8cwt gun.

edit: corrected "Incidentally, the Valentine had a Ø57.5" turret ring." to "Incidentally, the Valentine had a Ø50.0" turret ring." per new info.

 

[Shortround6]

I wonder, how much if any knowledge did the Western Allies have of the Soviet developments? I would suspect generally little, even after they became allies subsequent to the Barbarossa invasion?

How much they knew from newsreel footage, how much they knew from tanks in the Spanish civil war and how much they knew from other sources?
As shown by earlier posts, the real question is what did they know when. It taking about 2-3 years to get a tank from drawing board to large service use and 2 years was exceptional if the the tank was actual much good (reliable) when first introduced.

The title of the final book maybe points to the solution of the problem of too many different tanks.......The Soviets were perhaps pioneers in the widespread adoption of the universal tank concept, in that following their experiences fighting Japan in the late 1930'ies (Khalkin Gol etc.) they embarked on developing a heavily armored medium tank equipped with a gun big enough to also have a useful HE capability, which eventually resulted in the T-34.

Except that the Soviets stayed with the 3 tank concept pretty much through the first half of the war and stayed with 2 tanks (medium and heavy) for the duration. Some of this was to make up numbers and part of it was to use available manufacturing capability. The Soviets built over 14,900 light tanks 1941-43 and then switched the factories over to SU-76 production. I don't think that experiences fighting the Japanese in late 30s had much to do with Soviet tank development. They had adopted the T-28 tank in 1933 with the short 76mm and upgraded it several times during the 30s.

Though if we want the QF 75mm earlier, then maybe it's not realistic to assume one can piggyback on the American M2/M3/etc. work and use their 75mm shell

It is realistic, sort of, as that is what was done. Except it is too late, the US 75mm guns don't show up until 1940 when Watervliet Arsenal started design work after the Battle for France.

Maybe the WWI era 13pdr shell would roughly have been a usable starting point? Maybe not the 13-pounder gun itself, being wire wound it was perhaps not suitable to economic high volume manufacturing in the WWII era?

I have yet to figure out this idea of using old, obsolete, gun technology (construction, materials, propellent technology, shell design)to really speed up production of service weapons in the late 30s or early 40s. The 13pdr dates to 1903 and by 1913-14 the British were questioning it's usefulness. Using it as a starting point to get a 1930s weapon out of it means keeping the bore diameter and perhaps the rifling twist and changing everything else. Breechblock, recoil system, barrel construction, since we are looking for tank gun we don't have to upgrade (redesign) the actual carriage.
The shell designs aren't that good either.

HE with 262grams of HE. In part because of the 12.9lb weight (a heavier shell could use the same base and nose/fuse with a longer 'body' holding more HE.
British were using cheap steel for shell bodies to keep up production so thick bases and thick walls were pretty much standard.
The Ballistics for the 13pdr are not that impressive. 511ms (1675fps) velocity. Perhaps with 1930s propellent they could do better.
Production of 13pdrs was never great, they were intended as the support gun for the cavalry. Fewer than 500 built, production stopped in England before WW I started.
Britain, at least before WW I, had a number of gun manufacturers who were trying to sell guns not only to Britain and the colonies but to smaller European nations, South America, and non-colonies in Asia. They had a pretty good idea of how to design weapons given a decent list of requirements. Often the list of requirements were the problem.
The 13pdr was designed to go into action at the gallop.

There was another 13pdr. While they did try use the 13pdr as an AA gun it was far from ideal and somebody came up with the idea of using an 18pdr with a sleeve in the barrel to take 13pdr projectiles and use an 18pdr shell casing to get higher velocity. As far as gun, recoil system and breech goes it was basically an 18pdr.

 

[EwenS]

Incidentally, the Valentine had a Ø57.5" turret ring.

That is a figure I see on the Internet but what exactly is being measured?

Dick Taylor in his book about the Valentine "Into the Vally. The Valentine Tank And Deriviatives 1938-1960" gives it as

"Inside diameter 50"; ball to ball 52.8""

Maybe 57.5" is the external diameter of the turret ring?

 

[Shortround6]

The US adopted the French 75mm Gun Model 1897 in the early 1900s.

They adopted it in 1917.
After the US dealt with "the crime of 1916" 75mm gun the US army adopted the French 75 and British 18pdr with 75mm barrel liner as they were both in large scale production in the US and could be issued to the US troops in less time than fixing the US model of 1916 for another try and getting a workable weapon. Please note that in 1917 the British were working on an 'improved' 18pdr, keep the ammo, change just about everything else, entered production in the fall of 1918 with first issue in Nov 1918.

Turret diameters are only part of the story. If you use a longer barrel and bigger breech and bigger recoil system you need a taller turret or you have to accept less depression and elevation. British may have been asking for too much here but they (and the French) were fixated on WW I conditions and the need to fire down into trenches or being able to fire nose down.

There is a lot more to big guns than a first glance shows. It also requires a major change in thinking.

Short 76mm gun. 70 rounds of ammo, in part because of the 8000 rounds of machinegun ammo and space/weight taken up by the two machinegun turrets.
Also note that the main turret machine gun was not a co-ax with the main gun.
During the 1930s machine guns were seen either as main armament of the tank or very important. The cannon not always the primary consideration. It was used when machine guns would not do the job. The tank vs tank combat thing was not penetrating the heads of the some of the high commands.
The Soviets built over 2000 twin turret mg armed T-26 light tanks in the early 30s. The US built 310 M2 light tanks with twin turrets armed only with machine guns and further 113 M1 'combat cars' (another turf war thing) for the cavalry with a two man turret and two co-ax machine guns.

Not exactly the thing you want to copy. 4 man crew and 9-10 tons (thin armor) to move around a few machine guns?
What was the 'main armament" of the French Renault R-35?
The 7.5mm mg with 2400 rounds or short 37mm with 100 rounds (42 AP/58HE)?
However this also calls into question the wisdom of the British A11 Matilda I tank. Total of 140 ordered/built for a repeat of WW I.
But a tank just about equal in weight to a Renault R-35 but with 2/3s the speed (infantry support/speed doesn't matter?)
Supposed to carry 4000 rounds of MG ammo but not even the French 37mm grenade thrower to deal with harder targets (sandbags)?

Not even the Germans were all that sold on 75mm guns.
Standard (if we can say that about the Germans) battalions called for 4 tank companies in service. The MK IVs were in the 4th company in the early years. Depending on year and available tanks the MK IVs could be scattered a few per platoon in the 4th company up to all available tanks in the 4th company being MK IVs. Ideally the 1st company was mainly light/recon tanks. The 2nd and 3rd companies were the mediums with MK III or Pz 35(t) or Pz 38(t)s. In Poland and France a lot of 'slots' were filled by MK 1 and MK II tanks. tapered off after that.
Point is that the MK IV with the 75mm gun was NOT supposed to be the combat tank of the battalion/regiment. It was supposed to be the support tank of the battalion firing HE and smoke. Germans were somewhat quicker of the mark providing AP ammo to the 75mm guns when the 37mm guns were not as effective as thought.


We are calling for the British to adopt 1942/43 thinking in 1936-38 to get really good tanks in 1942/43. And to fund construction of new factories.

Now using hindsight we know that the Germans built as gun tanks....

Year...................1939+prewar.........................1940.....................1941.......................1942
MK II.....................1238......................................9(?).......................223..........................302
Pz-38.....................153........................................367......................678..........................168
MK III.....................255........................................862.....................1063......................2608
MK IV....................255........................................268.......................467.........................994

These should be close and do not count SP guns or other special purpose.
It shows that the MK IV was not the primary combat tank of the Germans during this time, it became so during 1942 with the long barreled 75mm making up 870 of the MK IVs produced. In 1943 the MK IV took over from the MK III. MK III gun tank production dropped into the basement while MK IV production tripled.
Germans had been making the MK III and IV in small numbers since 1937 and had time to sort out a lot of initial problems and to experiment with different suspensions and transmissions. The British were trying too many different things in a short period of time. One Reason the Valentine was reliable was that it used the A9/A10 power train and suspension/track. They had time to fix the obvious problems.

The "universal" came in when they finally realized that trench crossing was not one of the most important things in a tanks performance and that the ability to to get shot numerous times by AT guns while moving slowly across a battle field was also not a good tactic/strategy. Moving your company of tanks across the open ground in 1/2 the time even with lighter armor might give fewer total casualties? Save the heavy armor for the front.

 

[MikeMeech]

They adopted it in 1917.
After the US dealt with "the crime of 1916" 75mm gun the US army adopted the French 75 and British 18pdr with 75mm barrel liner as they were both in large scale production in the US and could be issued to the US troops in less time than fixing the US model of 1916 for another try and getting a workable weapon. Please note that in 1917 the British were working on an 'improved' 18pdr, keep the ammo, change just about everything else, entered production in the fall of 1918 with first issue in Nov 1918.

Turret diameters are only part of the story. If you use a longer barrel and bigger breech and bigger recoil system you need a taller turret or you have to accept less depression and elevation. British may have been asking for too much here but they (and the French) were fixated on WW I conditions and the need to fire down into trenches or being able to fire nose down.

There is a lot more to big guns than a first glance shows. It also requires a major change in thinking.
View attachment 832201
Short 76mm gun. 70 rounds of ammo, in part because of the 8000 rounds of machinegun ammo and space/weight taken up by the two machinegun turrets.
Also note that the main turret machine gun was not a co-ax with the main gun.
During the 1930s machine guns were seen either as main armament of the tank or very important. The cannon not always the primary consideration. It was used when machine guns would not do the job. The tank vs tank combat thing was not penetrating the heads of the some of the high commands.
The Soviets built over 2000 twin turret mg armed T-26 light tanks in the early 30s. The US built 310 M2 light tanks with twin turrets armed only with machine guns and further 113 M1 'combat cars' (another turf war thing) for the cavalry with a two man turret and two co-ax machine guns.
View attachment 832202
Not exactly the thing you want to copy. 4 man crew and 9-10 tons (thin armor) to move around a few machine guns?
What was the 'main armament" of the French Renault R-35?
The 7.5mm mg with 2400 rounds or short 37mm with 100 rounds (42 AP/58HE)?
However this also calls into question the wisdom of the British A11 Matilda I tank. Total of 140 ordered/built for a repeat of WW I.
But a tank just about equal in weight to a Renault R-35 but with 2/3s the speed (infantry support/speed doesn't matter?)
Supposed to carry 4000 rounds of MG ammo but not even the French 37mm grenade thrower to deal with harder targets (sandbags)?

Not even the Germans were all that sold on 75mm guns.
Standard (if we can say that about the Germans) battalions called for 4 tank companies in service. The MK IVs were in the 4th company in the early years. Depending on year and available tanks the MK IVs could be scattered a few per platoon in the 4th company up to all available tanks in the 4th company being MK IVs. Ideally the 1st company was mainly light/recon tanks. The 2nd and 3rd companies were the mediums with MK III or Pz 35(t) or Pz 38(t)s. In Poland and France a lot of 'slots' were filled by MK 1 and MK II tanks. tapered off after that.
Point is that the MK IV with the 75mm gun was NOT supposed to be the combat tank of the battalion/regiment. It was supposed to be the support tank of the battalion firing HE and smoke. Germans were somewhat quicker of the mark providing AP ammo to the 75mm guns when the 37mm guns were not as effective as thought.


We are calling for the British to adopt 1942/43 thinking in 1936-38 to get really good tanks in 1942/43. And to fund construction of new factories.

Now using hindsight we know that the Germans built as gun tanks....

Year...................1939+prewar.........................1940.....................1941.......................1942
MK II.....................1238......................................9(?).......................223..........................302
Pz-38.....................153........................................367......................678..........................168
MK III.....................255........................................862.....................1063......................2608
MK IV....................255........................................268.......................467.........................994

These should be close and do not count SP guns or other special purpose.
It shows that the MK IV was not the primary combat tank of the Germans during this time, it became so during 1942 with the long barreled 75mm making up 870 of the MK IVs produced. In 1943 the MK IV took over from the MK III. MK III gun tank production dropped into the basement while MK IV production tripled.
Germans had been making the MK III and IV in small numbers since 1937 and had time to sort out a lot of initial problems and to experiment with different suspensions and transmissions. The British were trying too many different things in a short period of time. One Reason the Valentine was reliable was that it used the A9/A10 power train and suspension/track. They had time to fix the obvious problems.

The "universal" came in when they finally realized that trench crossing was not one of the most important things in a tanks performance and that the ability to to get shot numerous times by AT guns while moving slowly across a battle field was also not a good tactic/strategy. Moving your company of tanks across the open ground in 1/2 the time even with lighter armor might give fewer total casualties? Save the heavy armor for the front.

Hi

The Soviet T-26 was the British Vickers-Armstrong 6-Ton Light tank (first arriving in Russia in 1930), which was then built in large numbers and variants by the USSR. A lot of Vickers designs were taken up in other countries.

The Soviets during the same period appear to have been quite keen on heavier multi-turret designs eg. T-28, T-29, T-32 and T-35.

Mike

 

[Elan Vital]

Obviously, as has been pointed out upthread, the tank turret size would have to be kept at the minimum of the Vickers Medium (Ø?" turret ring) and Cruisers Mk I, Mk II, and Mk III (all with Ø54.5" turret rings) at least. I am using this turret size and turret ring diameter as a minimum since they could all carry the 3.7"(94mm) Tank Mortar.

Incidentally, the Valentine had a Ø57.5" turret ring.

My understanding is that the actual available diameter is substantially smaller on Valentine than in any of the other main British tanks of the period. But they put quite a lot of effort in getting the most out of it.

Of note that sometimes the British mention not the minimum diameter, but the diameter to the ball bearings:

All Churchills have the minimum diameter at 54.25", 58.25 inches at ball bearing level, while Cromwell had those at 57.2 and 60 respectively.

In France, archives most often quote the diameter at the ball bearings and one is reliant on finding plans to figure out the real minimum diameters.

What was the 'main armament" of the French Renault R-35?
The 7.5mm mg with 2400 rounds or short 37mm with 100 rounds (42 AP/58HE)?
However this also calls into question the wisdom of the British A11 Matilda I tank. Total of 140 ordered/built for a repeat of WW I.
But a tank just about equal in weight to a Renault R-35 but with 2/3s the speed (infantry support/speed doesn't matter?)
Supposed to carry 4000 rounds of MG ammo but not even the French 37mm grenade thrower to deal with harder targets (sandbags)?

12 AP and rest HE for the most purely support-oriented loadouts. During the battle of France this increased to a 30% AP/70% HE mix and even more in cases when expecting an armored thrust.

I agree that A11 was probably overly unbalanced even for its role. Once fitted with the longer 37mm (or just supplied with enough 37mm APCR at minimum with short gun), the French infantry tanks have a genuine antiarmor capability. Speed was indeed higher and it does matter because infantry tanks may have to relocate to support other units or move to other fronts entirely. Prior to the BoF this was still just 25 kph requested at the minimum (12.5 kph road march which is already close to A11 maximum speed), and up to 40 kph after the BoF. Regardless of that speed limit the French had also specified a 10 hp/t ratio for new projects just to have minimum mobility, something the A11 was very far from.
10 hp/t was even a kinda implicit requirements as early as 1933 since they had been looking for about 90 hp engine for 9 tonne vehicles (and 60-70 hp for the OG 6 tonne vehicles), but the weight growth outpaced the search for adequate engines. Even then work was done throughout the late 30's to improve the P/W ratios of existing vehicles, the most successful effort being Hotchkiss H39 which pretty much reached 10 hp/t on top of a good top speed.

 

[z42]

Except that the Soviets stayed with the 3 tank concept pretty much through the first half of the war and stayed with 2 tanks (medium and heavy) for the duration. Some of this was to make up numbers and part of it was to use available manufacturing capability. The Soviets built over 14,900 light tanks 1941-43 and then switched the factories over to SU-76 production. I don't think that experiences fighting the Japanese in late 30s had much to do with Soviet tank development.

Obviously they used other tanks as well. I meant "universal tank" not in the sense that they would have produced only one type of tank, but rather the idea of a tank that's "good enough" for most tasks. Big enough gun to be useful for both AP and HE, decently fast and decently well armored. My understanding is that the development that lead to the T-34 (BT-7 -> A-20 -> A-32 -> T-34) was influenced by the experiences of the battles against the Japanese in the late 30s. From wikipedia:

After these battles, Koshkin convinced Soviet leader Joseph Stalin to let him develop a second prototype, a more heavily armed and armoured "universal tank" that reflected the lessons learned and could replace both the T-26 and the BT tanks. Koshkin named the second prototype A-32, after its 32 mm (1.3 in) of frontal armour. It had an L-10 76.2 mm (3 in) gun, and the same Model V-2-34 diesel.[5] Both were tested in field trials at Kubinka in 1939, with the heavier A-32 proving to be as mobile as the A-20. A still heavier version of the A-32, with 45 mm (1.77 in) of front armour, wider tracks, and a newer L-11 76.2 mm gun, was approved for production as the T-34.

Continuing on with the QF 75mm:

It is realistic, sort of, as that is what was done. Except it is too late, the US 75mm guns don't show up until 1940 when Watervliet Arsenal started design work after the Battle for France.

I meant that if the British want some kind of ~75mm medium velocity gun in use, say, a year or so earlier than historical, then adopting the French/US 75x350R shell might not have been politically feasible. In the historical timeline the choice was absolutely the right one, as by then it was clear the Americans were going to flood the theater with that ammo, it caliber was 'good enough' and well suited for the purpose. But a year earlier? Why adopt a foreign ~75mm caliber instead of picking one of the plethora of indigenous ones?

I have yet to figure out this idea of using old, obsolete, gun technology (construction, materials, propellent technology, shell design)to really speed up production of service weapons in the late 30s or early 40s. The 13pdr dates to 1903 and by 1913-14 the British were questioning it's usefulness. Using it as a starting point to get a 1930s weapon out of it means keeping the bore diameter and perhaps the rifling twist and changing everything else. Breechblock, recoil system, barrel construction, since we are looking for tank gun we don't have to upgrade (redesign) the actual carriage.

Seems people at the time thought that approach had merits, since just about everybody did it? The US 75mm tank guns used the French m1897 75mm shell (adopted by the US during WWI, if my understanding is correct), although presumably except for the shell casing dimensions there was little commonality. Similarly the Russian 76.2x385 used in the field guns and tank guns dated back at least to a Tsarist Russia artillery piece M1902.

The Ballistics for the 13pdr are not that impressive. 511ms (1675fps) velocity. Perhaps with 1930s propellent they could do better.

Indeed not. But OTOH maybe that could make for a lighter weight gun, allowing it to be mounted on a slightly smaller tank than the US M2 or Soviet L-11 tank guns with around 100m/s more MV? Of course, if you can convince the powers that be to adopt the US/French 75x350mm earlier than historical, by all means that would be a better choice, I just wonder how likely that is.

 

[tomo pauk]

The 13pdr dates to 1903 and by 1913-14 the British were questioning it's usefulness.

The Ballistics for the 13pdr are not that impressive. 511ms (1675fps) velocity. Perhaps with 1930s propellent they could do better.

Indeed not. But OTOH maybe that could make for a lighter weight gun, allowing it to be mounted on a slightly smaller tank than the US M2 or Soviet L-11 tank guns with around 100m/s more MV? Of course, if you can convince the powers that be to adopt the US/French 75x350mm earlier than historical, by all means that would be a better choice, I just wonder how likely that is.

The 'another' 13pdr gun offered 2000 fps, or 610 m/s. Will give both the French 75 and Soviet F34 and ZiS-3 a good run for their money, but more importantly, it would've offered a single-hit-kill vs. the German armor even in 1941, along with more than useful ballistics. Also good HE, smoke, canister ammo etc.
Make a new gun around that cartridge and you're set.

 

[EwenS]

The internal turret ring diameter on the M3 Lee / Grant was 54.5in

On the Canadian Ram, 60in, and on the M4 Sherman in all its forms, the M10 & the M36, 69in

 

[ThomasP]

re

Incidentally, the Valentine had a Ø57.5" turret ring.

That is a figure I see on the Internet but what exactly is being measured?

Dick Taylor in his book about the Valentine "Into the Vally. The Valentine Tank And Deriviatives 1938-1960" gives it as

"Inside diameter 50"; ball to ball 52.8""

Maybe 57.5" is the external diameter of the turret ring?

Dick Taylor is right - Ø50.0" turret ring for the Valentine it is, Ø57.5" is the external diameter. I found the diagram below:

 

[Shortround6]

The 'another' 13pdr gun offered 2000 fps, or 610 m/s. Will give both the French 75 and Soviet F34 and ZiS-3 a good run for their money, but more importantly, it would've offered a single-hit-kill vs. the German armor even in 1941, along with more than useful ballistics. Also good HE, smoke, canister ammo etc.
Make a new gun around that cartridge and you're set.

There were 4 75/76mm AA guns in service in WW I that could be possible solutions for starting a mid 30s tank gun. Possible does not mean practical in some cases.
British had 'standardized' on the 13pdr projectile for AA work so they wound up with.

QF 13 pounder 6cwt Mk III...............................1600fps...........................12.5lb
QF 13 pounder 9 cwt *.......................................2100fps (?).....................12.5lb
QF 12-pdr 12 cwt..................................................2200fps...........................12.5lb
QF 3 inch 20 cwt 1914.........................................2500fps...........................12.5lb
QF 3 inch 20 cwt 1916.........................................2000fps............................16lbs

*The QF 13 pounder 9 cwt gun was the 18pdr sleeved down to use 13pdr shells and use the 18pdr cartridge case. As used as an AA gun it had a 35in recoil stroke, They had tried 24in but they broke the mounts. This can be fixed/adapted. The QF 12pdr 12 cwt , being an ex-naval weapon, had a 12in recoil stroke.
The QF 3in 20 cwt shows the problems with increase velocity. for 52% more velocity they needed a gun that weighed 3.3 times as much. Yes it was overweight by even 1920s standards.
A 1930s tank gun could be made much lighter and recoil systems had made huge strides in WW I so WW II tanks had an easier time of it.
It also shows several problems with changing shell weights and loss in velocity.
The US 75mm Sherman tank guns fired a 14.7-15.2lb projectiles at about 2000-2030fps.
Maybe the British could have gotten a bit more velocity with the heavy shell by using a different propellent?
But trying to use 15lb projectiles out of the QF 13 pounder 9 cwt means you are down to around 1800fps?

Due to the British using economic (crappy) steel in their shells the HE content was small, Smoke is even worse.
British 13pdr shell held 262 grams of Amatol. US 75mm HE shell held 616 grams of Amatol.
The 13pdr is a lot better than the 2pdr and 6pdr but it is under 1/2 as effective as the Grant and Sherman guns.

Canister is not as useful as it sounds. May depend on the fuses in shrapnel shells, what is the shortest time they can be set to.
Canister is limited to around 200-300yds depending on the gun and size of the balls. It doesn't work well at very close range (under 50yds?) it needs room to spread out.
Shrapnel is like a variable-long range cannister round. The explosive charge just blows the nose off the shell and the shell body acts as a short low velocity gun with the balls fired out a very low additional velocity to the speed of the shell. The balls cover a V shaped pattern forward in the direction of travel. If the shell 'bursts' at 20-30ft height the balls can cover several hundred yards of depth and some width.
However this needs a bit work for the Crew. WW I artillerymen knew practically by heart the needed fuse settings. WW II tanks with a lot of other things to think about, trying to figure out shrapnel shell fuses (needed time delay) might not have worked well.

British, once they went to the BESA gun, had the best tank machine gun of the war. The Americans probably had the 2nd best, 3rd are the Germans.
After that things get dismal real quick with the Soviets, Italians and Japanese.

A lot less reason for cannister or shrapnel by the British.

Tanks of all nations had limited space and it took combat experience to show that for all nations, stored ammo was the biggest fire threat. Not type of fuel. British Crusaders were refitting armored storage bins for the 2pdr ammo. British didn't even want the driver to store his great coat in the fighting compartment. Crews still wanted to cram in extra shells where ever possible. Constant back and forth.

 

[tomo pauk]

*The QF 13 pounder 9 cwt gun was the 18pdr sleeved down to use 13pdr shells and use the 18pdr cartridge case. As used as an AA gun it had a 35in recoil stroke, They had tried 24in but they broke the mounts. This can be fixed/adapted. The QF 12pdr 12 cwt , being an ex-naval weapon, had a 12in recoil stroke.
The QF 3in 20 cwt shows the problems with increase velocity. for 52% more velocity they needed a gun that weighed 3.3 times as much. Yes it was overweight by even 1920s standards.
A 1930s tank gun could be made much lighter and recoil systems had made huge strides in WW I so WW II tanks had an easier time of it.
It also shows several problems with changing shell weights and loss in velocity.

I'm aware of the 20cwt, and as-is it would've made for an awful late-1930s tank gun. The two weaker guns are my favorites, one does not need a 40+ton tank to carry that in the battle. The 20cwt will also be using the bigger ammo.

A 1930s tank gun could be made much lighter and recoil systems had made huge strides in WW I so WW II tanks had an easier time of it.

The Vickers 75mm AA gun, that was exported to Romania, kinda shows the way. Have such a gun to be made for the 20cwt ammo (similar to this one) and there is a gun almost as good as the L43 7.5cm KwK.

 

[Shortround6]

Going back to the beginning and applying it to the army and tanks.

Similar to the other recent threads. What to make at home, what to import, what to export (in order to prop up the Allies, or perhaps as a diplomatic bribe), while having the realities of technology and budget at the time.

We are talking about 8-9 years here and there huge changes in budgets and technology during those years. What was practical in 1942 was not practical in 1938, let alone 1936.
Britain's situation also changed drastically due to the fall of France and Italy getting into the war. more later.

Significant increased investment in radar production methods & facilities (if practical) in order to get the working systems into service sooner and/or in larger numbers.

Radios also needed a significant increase in production and quality/performance. In North Africa in mid/late 1941 the Valentines that were there were swapping their No 11 radio sets for No 19 radios as fast as the replacement sets became available. The No 19 had been adopted in 1940 but supplies may have been restricted at first? The No 11 had been adopted in 1938 to replace the No 1 set that have been adopted in 1933. Basic range of the No 1 set is listed as 5 miles. The No 11 range is given as 3-20 miles but there were a number of different power supply and antenna options.
The No 19 had 3 channels. "A" set/channel was for "long range" which was about 10 miles. "B" set/channel was short range of about 1000yds for troops/squadron/company use and "C" channel was the crew intercom. A different times there were different setups for long range work. At the squadron or regimental level one HQ tank would tune it's radio to the higher command channel and would relay or alert the formation commander over the B set/channel. As the war went on there were some higher power A sets delivered for longer range work.

ALL of the electronics needs had to be balanced out. Radar equipment has to balanced against some sonars and against the radio needs of all the services.

Getting back more specifically to tanks. A 25 ton tank (give or take a few tons) that did 25mph with a medium 75mm gun (US M2ish?) would certainly have been a world leader in 1939-41. But could the British afford them in the numbers needed? Perhaps. They certainly spent a lot of money on tanks they could not use or shouldn't have used.

At the start of Operation Crusader (Nov 1941) the British had about 750 tanks (including reserves) . These were made up of Valentines, Matildas, Crusaders, some A 10s and A 13s and 3 regiments of Stuarts and a few MK VI light tanks mixed in. Granted the British were still clogging up the production lines with Covenanters but the chances of getting 500 of the super tanks seems a bit iffy.

Were Merlins realistically available for tank engines in the time period in question? Or was the Liberty the best option? Or a 3rd engine? The British wasted a lot of money on the large Meadows engine in the Covenanter. The engine in the Churchill worked but was it really better than an alternative.
What transmission/steering gear options do you really have? The 15-20 ton tanks can make do with clutch and brake steering. As the tank gets heavier a more sophisticated steering system becomes increasing desirable. Soviets made do with clutch and brake. They also broke down a lot. British used two alternatives to Clutch and Brake. Redundant or they didn't know?

We have the hindsight of knowing that the British would get kicked out of France in June 1940 and not be engaged in any major tank warfare until the Greek campaign (not that they did much) and then the beginning battles in NA.
We also have the knowledge that no matter what kind of WW II tank(or even modern tank) the British had sent to France or Greece it wouldn't have made any difference (or more than a couple of days).
We also have the hindsight to know that many of the problems in NA were caused be not enough development/testing and lack of training and poor tactics and doctrine.

Would a better tank have changed that? or was a combination of better equipment and better training and better tactics/doctrine needed?

Would a tank using a medium 75 been able to bull it's way through the Halfaya defenses? Larger tank with less armor depending on it's own to 75mm guns to make up for the lack of artillery support against dug in (or behind stone/mud walls) or would it just have caused more German causalities without actually forcing it's way through the position?
Senior commanders had broken the Matilda regiments into squadron (company) sized detachments and then set up an unrealistic time table.
The "attack" was supposed to have begun at 5:40 but the battery Assigned to C squadron had gotten bogged down in the sand and didn't reach it's firing position. At 6:00 with firing going on to west the Commander of C company decided to attack without artillery support. It took the Germans a few hours but they destroyed 12 out 13 Matildas.
British want HE firing tanks to prevent another repeat, But supply of HE tank ammo doesn't solve the problem of poor deployment (using a single squadron/company to take a key defensive position) poor communications (was another artillery battery within range to support the key attack if it's own assigned battery ran into problems), a stick to the time table mentality. Then we can throw in the stupid "fire while moving doctrine" that crippled long range shooting, even by the co-ax machine guns. The lack of effective local smoke, only a few 4in smoke throwers (the 2in smoke mortar was not mounted in Matildas.)
A 75mm armed tank may have been able to put smoke in front of the Germans and close range with fewer/no causalities. But it does not solve many of the other issues that the British had.