Alternative History Armoured Fighting Vehicles Part 4

[Cryhavoc101]

I have been reading into composite armour in MBTs and had always assumed that the Russians had been at least a decade ahead of the British and Americans when it came to composite armour

However the experimental T95 - 'Medium Tank' developed during the early 50s used siliceous cored armour and I understand that there was talk of using this armour in the subsequent M60 MBT

But I have been unable to learn why the M60 entered production and service without this armour - was there a reason why this armour was not used as it was then expected to offer about 1.5 x the protection against HEAT warheads than the equivalent weight of Steel armour ?

 

[Bougnas]

I have been reading into composite armour in MBTs and had always assumed that the Russians had been at least a decade ahead of the British and Americans when it came to composite armour

However the experimental T95 - 'Medium Tank' developed during the early 50s used siliceous cored armour and I understand that there was talk of using this armour in the subsequent M60 MBT

But I have been unable to learn why the M60 entered production and service without this armour - was there a reason why this armour was not used as it was then expected to offer about 1.5 x the protection against HEAT warheads than the equivalent weight of Steel armour ?

I've not found the definitive report which announced and explained the cancellation, but evidence from other reports would indicate that it was a combination of
- the starting costs and lead time to establish mass production capacity were not compatible with the swift deployment of M60 (though you could introduce it later: armor changes do not have the standardization issues that components which require maintenance do)
- the multi-hit durability problems with armor slabs. It is only after the cancellation in subsequent studies that small tiles of this composite demonstrated their superiority.
- Related to the above, the fact that the US and the West in general asked too much of new armor concepts compared to the Soviets, and as such had a tendency to abandon certain projects earlier than they should have even when a configuration would have been eventually viable. The Soviets generally had more realistic expectations.

Speaking of Soviet armor research, 1964 project for ERA on T-62, found by the owner of the CRIB blog in a russian magazine:

Soviet ERA concepts of the time tried to be as light as possible, so had a tendency to use aluminium instead of steel at the cost of performance against KE ammunition, 400kg in total. Protection levels was to be 100mm AP at point blank, early 115mm APFSDS at 1400 m/s (around 1.8km), and shaped charge with 450mm of penetration for 5-10 hits.

A very good coverage and pretty layout.

 

[JWilly48519]

Bougnas mentions "multi-hit durability problems". What radius of the core around a non-penetrating-hit location had its performance compromised for second and subsequent hits, and how bad was the performance degradation? Did that performance degradation occur with stacked HEAT devices, with a first charge intended to compromise the impact point, and the second charge actually doing the penetration?

 

[Bougnas]

To expand on that, a big complaint from US industry was that such large slabs were expensive to produce.

If it helps you, a report from 1955 said 2 sq feet slabs were better than 12 sq feet slabs, so that should give you an idea of just how much area can potentially be compromised.

 

[JasTysoe]

The Honey/Stuart had excellent mobility and other automotive characteristics, for sure, and its gun was combat-competitive at the beginning of the war, but the M2/M3/M5 family never had sufficient armor to be combat-survivable against anything with a decent gun.

Its "enthusiastic reception" was only because at the beginning of the war, USA was so far ahead of England, Germany and France in regard to engineering the automatic characteristics (mobility, and powertrain/suspension reliability and maintainability) of military vehicles.

The Honey/Stuart could not have become a combat-survivable AFV, because its fundamental design could not handle the weight of enough armor thickness.

The 'light-tank'-with-tracks concept was fatally flawed from its inception because that concept so universally was perceived as a combat vehicle. It always made more sense to develop wheeled vehicles with similar-to-light-tanks armor, armament optimized for escaping engagements rather than fighting through them, and similar-to-light-tanks ground pressure and therefore greater road range and speed, with more reliability and requiring less maintenance, at lower cost...and without that critical "it looks like a tank, we call it a tank, so it's a tank" flaw.

But the Stuart in 1941 was still competitive with the PzIII Ausf G (an Axis mainstay of the time) and the 1941 Stuart of our time line is also a different beast to a slower, more heavily armoured and upgraded 18 tonner along the same sort of general lines that could perhaps have been built in say 1936. The Somua S3 came out around then with a good 47mm gun, 25 mph speed and 47mm of armour and it is often considered close to the best tank at the outbreak of war. Surely the USA was capable creating something roughly similar but 9% lighter? The Pz III Ausf A to D were only 16 tons and they were sound, if not brilliant. medium tanks at the start of the war - surely the USA was capable of creating something similar but using the extra two tons wisely? In the late 1930s when a "decent gun" was a 37-47mm like the PaK 36, wouldn't such a tank have been very combat-survivable up until 1940, considering that the M3 Light rated quite well into 1941?

I'm not an expert on the technical side of armour development by any means so I may well be wrong, and I haven't dug into the reasons for 1930s US armour doctrine, but in terms of an alternative development I can see why they may well have done well to keep the older 18 ton bridging equipment and built an 18 ton medium tank.

 

[JasTysoe]

What might be expected from a 'Chad M3' tank, with regard to the armor, firepower and mobility?
3-men turret, or the 2-men turret remains?

In the interests of weight saving, perhaps the "2/3 turret"? . That is, fit three men into the M3 Light-sized turret like some British units did. Bob Crisp did so and his accounts don't complain about it; he writes of commanding the tank while the gunner and loader worked away.

 

[tomo pauk]

In the interests of weight saving, perhaps the "2/3 turret"? . That is, fit three men into the M3 Light-sized turret like some British units did. Bob Crisp did so and his accounts don't complain about it; he writes of commanding the tank while the gunner and loader worked away.

Is there still a need for a tank armed with 75 mm?

 

[CaptainCalvert]

Is there still a need for a tank armed with 75 mm?

You could do the local version of the OTL version of the M3 light with a 75 in an open turret. It would do the job OK, although really a CS M3 light starts to look interesting as an HE-armed support tank. The Brits have shown you can make a tank turret that can carry either a small bore AT weapon or a larger HE one. The biggest problem would be low ammo capacity in the small M3 light.

 

[tomo pauk]

You could do the local version of the OTL version of the M3 light with a 75 in an open turret. It would do the job OK, although really a CS M3 light starts to look interesting as an HE-armed support tank.

So we get the 75mm HE capacity, but lose the AP capacity, and sacrifice the roof?

The Brits have shown you can make a tank turret that can carry either a small bore AT weapon or a larger HE one. The biggest problem would be low ammo capacity in the small M3 light.

What was the weight of a lightest British tank that was outfitted with a 3-men turret (that also has a roof and a coax MG) and a gun that was at least as good as the French/US 75mm in both HE and AP capability?

 

[Cryhavoc101]

So we get the 75mm HE capacity, but lose the AP capacity, and sacrifice the roof?



What was the weight of a lightest British tank that was outfitted with a 3-men turret (that also has a roof and a coax MG) and a gun that was at least as good as the French/US 75mm in both HE and AP capability?

The Cromwell @ 27 tons?

 

[tomo pauk]

The Cromwell @ 27 tons?

Pretty much.
I was trying to point out that a good all-arounder ww2 tank (= turret for 3 men; gun suitable both for HE and AP work; decent protection, speed and range) will not be had at 18 tons. Even swapping the 'French 75mm' style gun with the 6pdr (in order to gain the MV, while loosing on HE ability) will still meant that weight is comfortably above 20 tons.
The 'no free lunch rule' applies as ever.

The lightest German tank with a gun that had good AP performance and useful HE shell, with 3-men turret, was probably the PZ-IIIJ, at 21.6 European tons. Armor on the IIIJ was still weak for mid ww2, with sides at 30mm thick; up-armored IIIL was one ton heavier.

 

[Cryhavoc101]

Pretty much.
I was trying to point out that a good all-arounder ww2 tank (= turret for 3 men; gun suitable both for HE and AP work; decent protection, speed and range) will not be had at 18 tons. Even swapping the 'French 75mm' style gun with the 6pdr (in order to gain the MV, while loosing on HE ability) will still meant that weight is comfortably above 20 tons.
The 'no free lunch rule' applies as ever.

The lightest German tank with a gun that had good AP performance and useful HE shell, with 3-men turret, was probably the PZ-IIIJ, at 21.6 European tons. Armor on the IIIJ was still weak for mid ww2, with sides at 30mm thick; up-armored IIIL was one ton heavier.

I would agree

And that Pz III was at the extreme limit of its design

25 plus tons is more likely with a decent armour scheme, engine and crew layout and sufficient ammunition and fuel.

At 18 Tons you have to sacrifice several of the above features i.e. later Valentine with the 75mm but cramped turret and slow speed or a tank destroyer with little armour (and saying that the Wolverine was nearly 30 tons) or an assault gun with no turret (and the most famous one the Stug III with an L48 is 24 tons)

 

[dxe131]

local version of the OTL version of the M3 light with a 75 in an open turret

Are you referring to the T18 HMC? Not exactly a successful design.

T18 HMC: Quick Howitzer

A blog about World War II era archive documents, primarily dealing with armoured warfare.

www.tankarchives.ca

 

[JasTysoe]

Is there still a need for a tank armed with 75 mm?

Definitely at a later date, but not in the 1924-1927 time frame that was being discussed when I entered the chat (or not in a high velocity form). That period was when it was decided that 18 tons was the upper limit to tank mass due to bridging limits.

My basic point that if the decision to make an 18 ton tank had been followed from about 1924/27 onwards, it could have led to some very useful (if imperfect) tanks being developed. By the late '30s this could have resulted in a series of 18 ton (stripped) tanks that would have been quite competitive in the early war, just as the 16 ton PzIII Ausf D and 18.1 ton PzIV Ausf C were.

It's also quite possible that a 1930s tank to the 18 ton limit could have been designed to have been as flexible as the Pz IV, which as we know was upgraded to remain quite competitive until the end of the war.

Sure, in later years there would have been a need for bigger tanks and so the bridging kit would have needed upgrading, but arguably in the '20s and early '30s it would have been better to have spent the available resources on 18 ton tanks, rather than either building light tanks OR building the proposed 23-25 tonners AND diverting scarce resources to upgrading bridging kit for the bigger tanks.

 

[JasTysoe]

I would agree

And that Pz III was at the extreme limit of its design

25 plus tons is more likely with a decent armour scheme, engine and crew layout and sufficient ammunition and fuel.

At 18 Tons you have to sacrifice several of the above features i.e. later Valentine with the 75mm but cramped turret and slow speed or a tank destroyer with little armour (and saying that the Wolverine was nearly 30 tons) or an assault gun with no turret (and the most famous one the Stug III with an L48 is 24 tons)

Yes, for the mid- to late-war period an 18 tonner won't cut the mustard. But the success of the early PzIII and Pz IV, the Somua S35 and other smaller tanks in the early war period shows that an 18-19.5 ton tank was capable of front line service with success at that time. The 18 ton bridge limit was therefore not going to stop the US from designing tanks that could serve well from 1927 up till about 1941.

Another point is that a US tank isn't just aimed at ETO combat, of course, and a good line of 18 tonners would seem to have been very useful in the PTO.

 

[Hammerbolt]

One thing I do love about the M2 medium and lights was the stunning number of machine guns. The medium could carry up to nine, and the light had five! The medium carried over 12000 rounds! Was there some secret MG lobby in the US?

 

[CaptainCalvert]

One thing I do love about the M2 medium and lights was the stunning number of machine guns. The medium could carry up to nine, and the light had five! The medium carried over 12000 rounds! Was there some secret MG lobby in the US?

Your suggestion looks disturbingly plausible, but I think it's more that WW1 experience showed that mgs and driving over guns were usually more useful than HE throwers.
From what I've read, the Renault FT with 37mm struggled to cope with infantry, which is why they were issued with canister rounds. Since the mg armed ones didn't get a major overhaul, it suggests they worked OK.

 

[Driftless]

One thing I do love about the M2 medium and lights was the stunning number of machine guns. The medium could carry up to nine, and the light had five! The medium carried over 12000 rounds! Was there some secret MG lobby in the US?

I don't know the thinking behind the plethora of MGs. Would it have been considered more useful in the jungle (i.e. Philippines), urban fighting, or all battlefields?

 

[JWilly48519]

One thing I do love about the M2 medium and lights was the stunning number of machine guns. The medium could carry up to nine, and the light had five! The medium carried over 12000 rounds! Was there some secret MG lobby in the US?

Go back a few pages to Bougnas' posting of US Army tank development history, wherein the Infantry decided it maybe wanted a medium tank for breakthroughs, and definitely wanted a light tank with a lot of MGs to tactically support infantry forces on the battlefield. The M2, eventually, was the realization of that MG-armed light tank.

 

[JWilly48519]

Your suggestion looks disturbingly plausible, but I think it's more that WW1 experience showed that mgs and driving over guns were usually more useful than HE throwers.
From what I've read, the Renault FT with 37mm struggled to cope with infantry, which is why they were issued with canister rounds. Since the mg armed ones didn't get a major overhaul, it suggests they worked OK.

Note that the later evolution of the FT was to the casemate version, armed with a short Schneider 75mm...because the 37mm's weak HE was insufficiently lethal to enemy strongpoints, and a 75mm HE round was deemed the needed amount of lethality.

The casemate also...I understand...allowed room for a two-man topside crew, which was more effective under the pressures of combat with its need for rate-of-fire and command situational awareness and gun aiming.