Britain orders the 16 tonner Mk III tank into Serial production - how does this change British AFV development

e 3in is useless HE thrower, but 2 pdr is adequate for the job? Any math to back up this?
The 3"CS 'gun' or Howitzer was closer to a mortar, and was typically only supplied with smoke rounds, with only four HE for self protection.
It lobbed almost 14lbs rounds at 650fps, a 81mm mortar did 700fps, for a much heavier shell while a 60mm was 520.

It was a good shell, but I imagine accuracy was an issue.
 
In 1939 everyone who was building tanks pretty much had them armed with 37mm cannon (Germany), 45mm Russia, 37mm and 47mm France, 40mm Britain

There must have been some common evolution in order for the major tank building nations to all decide on a weapon in the 37mm - 47mm range and have dedicated 'Howitzer armed' tanks

At this time the British made separate CS (Close support) versions of the same tanks armed with 3.7" / 94mm Howitzer gun - but mainly to fire smoke

The Germans had the Pz IV with its short 75mm - again for HE and smoke

The French were packing the Char B - this was the only real proper large gun armed main tank of the day and it had a lot of flaws

The Russians would build the KV1 and KV2 from 1940

So all this talk of the British being silly and only having a 40mm gun is a bit off when everyone else was doing it!!!

And the HE filler of a 37, 40, 45, 47mm shell is pretty much that of a hand grenade
 
But it still had a tiny amount of HE, as it wasn't thinwall, or to the extreme what the Russians did with their 45mm, trading MV for HE content, with nowhere close to the same trajectory as AP

The other sin of the 2pdr, as it's just light and small enough to be balanced, to where Free Elevation is possible- where the gunner can balance the breech on his shoulder, for some measure of accuracy while firing on the move.
To get the the British went with internal gun mantlets, that in the future would limit gun size.

Didn't have to be that way, as the US was able to make the Mk2 and Mk3 75mm balanced well enough with external mantlet for a stabilizer to function- when both stabilizer and geared elevation was disengaged, its balanced enough you can move the piece with your little finger.
But the British did not move away from internal mantlets until late in the War.

Anyway, the Mediums would have the old 3pdr at first, til 1936 or so.
In my dreams they would get 18 pdrs at this point, for a true dual purpose gun, finding that the 3" Mortar just isn't great at its job of close support.
What you are losing sight of is that this a development process. There has to be a reason for the British Armoured Corps to seek a heavier gun. They had not experience of the 2 Pdr in action before 1939. Then there was Dunkirk's loses to make up for. Until 1941, the 2 Pdr was quite an adequate armour piecer. What was required was for the Armour Corps to be issued with the 2 Pdr. He. 2 Pdr He was more than adequate for defeating AT guns and softskin transport. The 2 Pdr only started to show it's obsolesce when Germany uparmoured it's Panzer III. Then the 6 Pdr became a necessary weapon.
 
There has to be a reason for the British Armoured Corps to seek a heavier gun.
WWI pointed out that machine guns alone was not enough, needed to be able to toss a HE shell at MG nests, since some German MG nests had steel plate protection.
Shooting 2pdr shot at a AT gun, that's no better than using it as a big sniper rifle, since there wasn't much HE to be had, and would have less TNT than a grenade
 
WWI pointed out that machine guns alone was not enough, needed to be able to toss a HE shell at MG nests, since some German MG nests had steel plate protection.
Shooting 2pdr shot at a AT gun, that's no better than using it as a big sniper rifle, since there wasn't much HE to be had, and would have less TNT than a grenade
If that is all they are required to do then the 2 Pdr is more than adequate. All they need is to be issued with the round which was developed in the 1930s. Of course they would require training and permission to fire it. You seem to be seeking a massive explosion which was not necessary.
 
If that is all they are required to do then the 2 Pdr is more than adequate. All they need is to be issued with the round which was developed in the 1930s. Of course they would require training and permission to fire it. You seem to be seeking a massive explosion which was not necessary.
As much as it was possible to go as big as the 18 pdr, realistically the 3 Pdr(47mmL50) could have a somewhat useful HE round, and similar performance to what the Soviet 45mm had, provided the UK put any thought into projectile development.

For a hole puncher, the UK didn't put much thought into testing that round against armor, or they would have found that APC was needed, minimum and APCBC for long range performance(that didn't show in time for the Desert), rather than finding out that against FH armor, AP shattered without penetration
 
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As much as it was possible to go as big as the 18 pdr, realistically the 3 Pdr(47mmL50) could have a somewhat useful HE round, and similar performance to what the Soviet 45mm had, provided the UK put any thought into projectile development.

For a hole puncher, the UK didn't put much thought into testing that round against armor, or they would have found that APC was needed, minimum and APCBC for long range performance, rather than finding out that against FH armor, AP shattered without penetration
You are thinking far, too far ahead of reality there. They would not have needed APC or APCBC until they knew what it's perforance in combat was. That wasn't going to happen until 1940. The gun was obsolete by 1941. When would an APC or APCBC round be available? When the gun was being discarded in favour of the 6 Pdr. These things take time and a lot of effort to develop and prove.
 
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They would not have needed APC or APCBC until they knew what it's perforance in combat was.
Testing was abysmal, as well as theory for what was needed

'What happens if the Germams build a tank with the same armor as our A11 Matilda MkI, 60mm? can we knock that out?'

'Pip pip Old Bean, Jerry won't do that'
 
Testing was abysmal, as well as theory for what was needed

'What happens if the Germams build a tank with the same armor as our A11 Matilda MkI, 60mm? can we knock that out?'

'Pip pip Old Bean, Jerry won't do that'
The point is, Jerry didn't do that until late 1941 with the Panzer III Ausf J. I could foresee the 25 Pdr being pressed into service as a tank gun as happened with the ACIII Sentinel in Australia if the Germans had created an equivalent to the 'tilly. The 2 Pdr was then obsolescent and the 6 Pdr was then issued in early 1942. The 6 Pdr was available much earlier but it wasn't placed into production because of Dunkirk. The biggest problem is that the British idea of combined arms was centred on arillery fire. It had won WWI for them and it had been refined by 1939. The British didn't have a "doctrine" as such but rather a philosophy on how to conduct a battle which was founded on experience in WWI - Artillery softened up and covered the approach of infantry, supported by armour, which followed closely a steadily advancing bombardment on and over the enemy positions.
 
The point is, Jerry didn't do that until late 1941 with the Panzer III Ausf J. I could foresee the 25 Pdr being pressed into service as a tank gun as happened with the ACIII Sentinel in Australia if the Germans had created an equivalent to the 'tilly. The 2 Pdr was then obsolescent and the 6 Pdr was then issued in early 1942. The 6 Pdr was available much earlier but it wasn't placed into production because of Dunkirk. The biggest problem is that the British idea of combined arms was centred on arillery fire. It had won WWI for them and it had been refined by 1939. The British didn't have a "doctrine" as such but rather a philosophy on how to conduct a battle which was founded on experience in WWI - Artillery softened up and covered the approach of infantry, supported by armour, which followed closely a steadily advancing bombardment on and over the enemy positions.
My understanding is that the Sentinel was fitted with a 'pair' of 25 pounders in order to simulate the recoil of a 17 pounder ATG on the design due to the 17 pounder weapon not being available at the time. It was not intended to be a 25 pounder armed design.

Combined arms being centered on artillery fire has not changed very much since the 100 days offensive (if not before Cambrai).

Other than improving through better comms and equipment and methods the fact remains that artillery fire (both 105mm and 114mm NGS) was the biggest differentiator in battle between the British and Argentine forces in 1982 and during the 1991 gulf war the use of 155mm and MRLS artillery to shoot in a given assault was the norm.

Obviously M1s and M2 Bradleys blitzing through an entire Rep Guard tank Battalion in 30 seconds flat with zero losses is much cooler - but that was not the norm.

If it aint broke
 
Re the guns for this setting, why not keep the 3lber and just modernize that? Its a 47mm gun which was quite common in the world at the time, the Japanese and Russians used a 47mm gun as the gun for their most common tanks (BT series, T-26 etc) And as its slightly bigger, you can fit a bit more explosives in there if you wanted to make a HE round. Its still going to basically be a grenade, but a bigger one than the 2lb HE round.
 
Why did the British stick to the OQF 3 pdr when the Hotchkiss 6 pdr was available? The 6 pdr offered better armor penetration and HE content in the same gun. The additional weight, reduction in number of shells carried, and increased space required were easily offset by the more powerful shell. The 2 pdr was a step backwards. The next step should have been OTL OQF 6pdr/7 hwt or a development of the 13 or 18 pdr guns.

I would propose a Six Ton based 12-15 ton Medium tank using a Hotchkiss derived gun, note they were built in several lengths. Additional 6 pdr guns were under development by the RN early in the century.
Hmm... The Royal Navy had a new 6 pounder 10 cwt under design about 1928ish and coming into production 1933-34. Not as good as the 6 pounder AT, but a muzzle velocity of 730 m/s ain't half bad, and as an anti-shipping weapon you'd assume it'd have an HE shell...
 
German 37mm had 24g
US 37mm had 39g of high explosive
Soviet 45mm had 100-135g

US WWII Hand Grenades had upto 66g of explosive, Soviet 60g
And a British 2" mortar HE had 300 grams of explosive filler

So where the 2 pounder was found wanting which was the long range engagements in the often featureless desert battlefields of North Africa - where dug in Anti tank guns out ranged the 2 pounder armed cruisers I seriously doubt that a dinky HE shell would have been useful.

Far more useful would be a robust comms link and the combined arms cohesion to allow a given tank unit commander to call up his associate in the attached RA unit (preferably via someone embedded in his command chain) to 'learn' those German bounders with a 25 pounder 'stonk'.
 
My understanding is that the Sentinel was fitted with a 'pair' of 25 pounders in order to simulate the recoil of a 17 pounder ATG on the design due to the 17 pounder weapon not being available at the time. It was not intended to be a 25 pounder armed design.
That was, as you note a trials weapon. The ACIII was designed with the 25 Pdr in it's turret.



The twin-25Pdr vehicle proved that it could take the recoil from the 17 Pdr gun on that sized turret ring. Interestingly, the report from that trial found it's way to the UK and directly influenced the design and development of the British Firefly tank. Until then, they hadn't thought it possible to mount such a powerful weapon in the Sherman.

Combined arms being centered on artillery fire has not changed very much since the 100 days offensive (if not before Cambrai).
It took the British Army two years of trial and error to develop the use of artillery to the extent that it basically won the Western Front for them. An artillery bombardment wasn't new. What was new was a marching barrage to convey the infantry (and armour) onto and over the enemy position. It was considered better to hug the rear end of the barrage and if necessary suffer casualties as a consequence than to fall behind it and allow the enemy to emerge from his dugouts and mount the trench firesteps again.

Other than improving through better comms and equipment and methods the fact remains that artillery fire (both 105mm and 114mm NGS) was the biggest differentiator in battle between the British and Argentine forces in 1982 and during the 1991 gulf war the use of 155mm and MRLS artillery to shoot in a given assault was the norm.
Until 1945 the British Army was more interest in forcing the enemy to take shelter and be neutralised that way than to destroy the enemy. The US Army was more interested in destroying the enemy with it's field artillery hence the difference in calibres with 25 Pdr being 89mm and the 105mm calibre. This has since become merged with 155mm, with the balance going at the Americans' insistance to destruction over neutralisation. In 1945 the Royal Armoured Corps carried out an experiment where they deliberately drove a squadron of Churchill tanks into the beaten zone of a 25 Pdr battery. The Churchill's basically emerged unhurt (with except for a few aerials broken/removed).
 
It took the British Army two years of trial and error to develop the use of artillery to the extent that it basically won the Western Front for them. An artillery bombardment wasn't new. What was new was a marching barrage to convey the infantry (and armour) onto and over the enemy position. It was considered better to hug the rear end of the barrage and if necessary suffer casualties as a consequence than to fall behind it and allow the enemy to emerge from his dugouts and mount the trench firesteps again.
But if they realized the implications of it after the war they wouldn't have kept so much defensive-oriented warfare in their army after the war. They demonstrated that even the strongest defenses or fortresses were ineffective against those tactics, that there was no effective defense against them, and therefore that defensive tactics in general were obsolete. There was no point in preparing defenses that would have failed so the only thing to use in all modern high-intensity scenarios are offensive tactics.

Had they recognized this the British Army wouldn't have bothered to continue to train troops to dig trenches or create other defensive positions, or make inherently defensive weapons like anti-tank guns or infantry-heavy formations. They could have freed up all that extra money and effort for the offensive parts of the army like tanks and mechanized forces (and even then they wouldn't need to bother with defensive tactics). As a side effect, this would create the conditions to buy better tanks like the A6 or whatever was chosen.

They could have similarly realized the importance of air support and air superiority which is even more effective (and makes land forces almost entirely irrelevant), but that's a different subject.
 
That was, as you note a trials weapon. The ACIII was designed with the 25 Pdr in it's turret.



The twin-25Pdr vehicle proved that it could take the recoil from the 17 Pdr gun on that sized turret ring. Interestingly, the report from that trial found it's way to the UK and directly influenced the design and development of the British Firefly tank. Until then, they hadn't thought it possible to mount such a powerful weapon in the Sherman.



It took the British Army two years of trial and error to develop the use of artillery to the extent that it basically won the Western Front for them. An artillery bombardment wasn't new. What was new was a marching barrage to convey the infantry (and armour) onto and over the enemy position. It was considered better to hug the rear end of the barrage and if necessary suffer casualties as a consequence than to fall behind it and allow the enemy to emerge from his dugouts and mount the trench firesteps again.



Until 1945 the British Army was more interest in forcing the enemy to take shelter and be neutralised that way than to destroy the enemy. The US Army was more interested in destroying the enemy with it's field artillery hence the difference in calibres with 25 Pdr being 89mm and the 105mm calibre. This has since become merged with 155mm, with the balance going at the Americans' insistance to destruction over neutralisation. In 1945 the Royal Armoured Corps carried out an experiment where they deliberately drove a squadron of Churchill tanks into the beaten zone of a 25 Pdr battery. The Churchill's basically emerged unhurt (with except for a few aerials broken/removed).
The suppression of dug in enemy was treated as a science by the RA in WW1 and beyond

As for Churchills driving through a stonk - that might work for Churchills in 1945 (which to a 1939 tank design might have well have been drop forged from a single chunk of armor plate using a dead sun) - but it is not going to help the infantry, engineers and SPAs that are accompanying them.

Plenty of DAK and Italian armored attacks in north Africa were broken up by a timely dose of 25 pounder - often leaving a number of tanks disabled.

Then there is the morale effect

A near miss from a 25 pounder shell is unlikely to kill or injure buttoned up crew in an AFV

However a direct hit on an early war tank such as the PZIII and IV is like to wreck the vehicle and kill everyone on board - this leads to a 'reverse lottery' syndrome ie very unlikely to 'win' but no one want to be in it.

The same thing was true of a Jabo attack - Typhoon and P47 rocket attacks caused very few tank losses but non of the crews wanted to be in that lottery and crews would often abandon the tanks and take shelter (often placing themselves at greater risk by doing so)

And of course anything not an AFV was very vulnerable to artillery fire and tanks alone, stripped of their supporting arms would not carry a battle.

As for 105 replacing the 25 pounder - I think this was more a case of standardization across the NATO partners than anything else
 
In 1939 everyone who was building tanks pretty much had them armed with 37mm cannon (Germany), 45mm Russia, 37mm and 47mm France, 40mm Britain
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There must have been some common evolution in order for the major tank building nations to all decide on a weapon in the 37mm - 47mm range and have dedicated 'Howitzer armed' tanks.
Primate perceive, primate perform.

At this time the British made separate CS (Close support) versions of the same tanks armed with 3.7" / 94mm Howitzer gun - but mainly to fire smoke
NTB.
The Germans had the Pz IV with its short 75mm - again for HE and smoke
The French were packing the Char B - this was the only real proper large gun armed main tank of the day and it had a lot of flaws
1939 after Poland; Uncle orders a tank with a gun/howitzer===> M3 Lee, so does everyone else a similar type. Meanwhile... in 1937. In other news Mikhail Korshin was working on the T-34 in the same year. Again with a 3 inch bore gun.

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Links in the evolution of the T-34, left to right: BT-7M, A-20, T-34 mod. 1940 (L-11), T-34 mod. 1941 (F-34).

Source? Tank encyclopedia.

Early precursor: The A-32

From the BT-IS, A-20, the BT-SV’s sloped armor (1936) to the five-roadwheel A-32, the blueprint of the T-34 was set up far before the war. The team lead by engineer Mikhail Koshkin promised Stalin to replace the BT series with a better “universal tank”. The bureau designed a sloped armored box encasing a powerful diesel V12 engine which was less sensitive than the high-octane petrol engines used in previous Soviet tanks. This was done both to increase the range and to avoid bursting into flames too easily, as the BT-5 and BT-7 did during the war against Japan in Manchuria.
You know what they say... the stupid shall be... etc. With Stalin that comes with a side order of insane.
The Russians would build the KV1 and KV2 from 1940
So all this talk of the British being silly and only having a 40mm gun is a bit off when everyone else was doing it!!!
Well, almost everybody.

And the HE filler of a 37, 40, 45, 47mm shell is pretty much that of a hand grenade
A hand grenade equivalent is still a lot better than nothing; provided the burst radius includes the AT gun crew or machine gun nest inside of it.

Otherwise agree with your views 100%
 
Establish the Experimental Mechanized Force of 1928-30 as a permanent unit within the Army. From this base, determine the needs of the British Army for equipment and training. You could have a decision by 1934/5 to create 3-4 independent mechanized brigades and 4-6 tank battalions to support the infantry/motorized infantry divisions. Such a base would teach the British lessons on equipment and combined operations. The early lessons were heading in the right direction.
(£)
I am not a fan of the Christy system. Repair in the field is impossible. Units will receive damage in combat. Thus, tanks must be returned to depots for repairs. The Horstmann design allows repair in the field. The improvement in smoothness of ride, and a slight speed advantage, are insufficient to account for the delays in repairs of damaged vehicles.
Horstmann in the 1930s has an upper mass and speed limit. If one wants a fast tank... bell-crank is the way, or torsion bar. Flip a coin.
Why did the British stick to the OQF 3 pdr when the Hotchkiss 6 pdr was available? The 6 pdr offered better armor penetration and HE content in the same gun. The additional weight, reduction in number of shells carried, and increased space required were easily offset by the more powerful shell. The 2 pdr was a step backwards. The next step should have been OTL OQF 6pdr/7 hwt or a development of the 13 or 18 pdr guns.
(£)

I would propose a Six Ton based 12-15 ton Medium tank using a Hotchkiss derived gun, note they were built in several lengths. Additional 6 pdr guns were under development by the RN early in the century. Cardin utilized the Horstmann suspension in the late 20's for light tanks. Thus the British Army could have a 14 ton, 57 mm armed, Horstmann suspended medium tank by 1933/4 if they requested one. With 25-30 mm armor and 120-180 horsepower available in the AEC engine, such a tank would have been equal to any German tank before 1941.
(£)

Such a tank would also be cheaper to build than the 16 Ton Mk III. The British needed numbers, Which is why they built so many light tanks. They would certainly not build the 16 Ton Mk III in the same numbers as the light tanks as has been suggested. That tank was too expensive.
Convince an accountant.

Sidebar.

I am not a fan of the Christy system. Repair in the field is impossible. Units will receive damage in combat. Thus, tanks must be returned to depots for repairs. The Horstmann design allows repair in the field. The improvement in smoothness of ride, and a slight speed advantage, are insufficient to account for the delays in repairs of damaged vehicles.
The reason the US army rejected it, besides that Walter Christie was an asshat... was (^^^).
 
Re the guns for this setting, why not keep the 3lber and just modernize that? Its a 47mm gun which was quite common in the world at the time, the Japanese and Russians used a 47mm gun as the gun for their most common tanks (BT series, T-26 etc) And as its slightly bigger, you can fit a bit more explosives in there if you wanted to make a HE round. Its still going to basically be a grenade, but a bigger one than the 2lb HE round.
They should have.
The Vickers Naval 3 pdr in WWI trim fired a 3.3 pound shell at 2500fps
plugging that into a penetration calculator for standard AP gives 57mm 40mm@30 degrees, while HE shell seemed to have 60g of explosive
 
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