Tank & AFV armament alternatives, 1935-45

[Jabberwocky]

The British were on the Path at least as well as anybody else. Then they went off the path and fell in the canal.

I get the feeling this was partially a result of the shuffling round of responsibility & oversight for British tank design in the 1936 to late 1941 period, plus the spreading around tank design/development efforts too much.

You had Nuffield, Vickers, Leyland, Harland & Wolf, Morris, Vauxhaul, Birmingham Railway, LMS Railway (and maybe a couple others as well) all involved in tank design up to 1942. It wasn't until the formation of the Tank Board in 1940 and then the introduction of the Directorate of Tank Design in 1941 that things started to get better.

Yes, you still ended up with run of the mill designs (Cromwell) and some outright poor designs (Challenger and Comet come to mind), but you also see a much better design-test-re-design cycle.

 

[z42]

Yes, you still ended up with run of the mill designs (Cromwell) and some outright poor designs (Challenger and Comet come to mind), but you also see a much better design-test-re-design cycle.

Hmm, what's so bad about the Comet? IMHO British tank design started to hit its stride with the Cromwell, which was ok-ish. Could have traded some of that speed for more armor though. Comet was basically Cromwell done right, with more armor and a better gun. And then leading to the Centurion, arguably the best all-round tank of its era.

That's the tragic irony of it, after muddling through the war with mostly sub-par (or worse) tanks, they then go on to design the best general purpose tank in the world, just in time to miss the war.

 

[bf109xxl]

Soviets don't have much in production, they skip over the sweet spots with the T-28 (way to big/complicated) and the BT-7 and T-26 good guns but 3 man crews have problems.

The Soviets developed the T-50 - the best light tank in 1941 (and maybe during the entire war) which was in production and should be produced in much greater numbers than the T-34. It was far better than any Soviet wartime improvisations, such as the T-70 and any Allied light tank. In this discussion, the existence of the T-50 is persistently ignored, even though it was the tank that was to become the Soviets' main tank.

The Early T-34s in 1940 have poor vision, poor radios (those that had them), had the BMG but that is were the 4th man was, not helping with the main gun which was the tanks reason for being.

In the hands of experienced crews, even the early T-34 with all its shortcomings was unequivocally more optimal in 1941 (excluding the T-50). Unfortunately, the Soviets could not ensure its adequate development during the war (in mass series) due to numerous technological problems. And huge losses due to non-technical reasons conceal the true effectiveness of the T-34 in the initial period of the war. The Soviets developed the most adequate tank design concept, but abominably realized it due to low technological level. All others had a much higher technological level, but conceptually created less suitable design, which was either too complicated to be produced in sufficient numbers or had insufficient characteristics / numerous flaws, etc.

Just slinging in a bigger gun doesn't solve any of these problems. Look at the early T-34s in Russia. They had stuffed 76mm guns in a turret designed for a 45mm gun. Yes they had the 76mm guns but they had a very bad rate of fire. 5 rpm on a test range? 2-3 rpm in actual combat?

Considering that no one could hit any target from a moving tank (perhaps with the exception of the Panther), this rate of fire on the battlefield was not a problem. The problem was to locate the target - the commander was distracted by cannon handling, and the quality of the observation equipment has already been mentioned.
I am not surprised at the persistence with which this discussion ignores the simple fact that the tank should not have been primarily designed to fight against its own kind - it is a common mistake. This - fighting against its own kind as primary combat role - was rather a specific feature of German tanks which were used in the second half of the war mainly as anti-tank self-propelled guns. But for the Soviets, and indeed for the Allies, this was not the primary combat role for tanks.

Summarizing: everybody needed the T-54 already in 1939 - with a better transmission and crew compartment isolation.

 

[yulzari]

Yes, you still ended up with run of the mill designs (Cromwell) and some outright poor designs (Challenger and Comet come to mind), but you also see a much better design-test-re-design cycle.

The Challenger was not a poor tank. Not wonderful but an excellent support for Cromwells and easier to fight than a Firefly not to mention having similar maintenance systems to the Cromwells, being a stretched Cromwell.

I admit that the Charioteer suggests that they could have simply used normal Cromwells adapted to a new turret as the Charioteer took the 20 Pounder and was tested successfully with the same 105mm L7 gun as is going into the new USA support tank today. Before anyone says so, yes, I am aware that the Charioteer was classed as a self propelled anti tank vehicle not a tank given the thin turret armour.

 

[Elan Vital]

The Soviets developed the T-50 - the best light tank in 1941 (and maybe during the entire war) which was in production and should be produced in much greater numbers than the T-34. It was far better than any Soviet wartime improvisations, such as the T-70 and any Allied light tank. In this discussion, the existence of the T-50 is persistently ignored, even though it was the tank that was to become the Soviets' main tank.

What about the American M24 in 1945? It mounts a 75mm gun in a 3-man turret, although it is arguably less efficient automotively and less well armored.

T-50 absolutely is the best light "Infantry support" tank however.

 

[bf109xxl]

What about the American M24 in 1945? It mounts a 75mm gun in a 3-man turret, although it is arguably less efficient automotively and less well armored.

The T-50 had plenty of reserves for modernization - perhaps other than installing a more powerful gun (thus, the T-34 was indeed more optimal solution despite of all its shortcomings!). It is hard to say what it would have been by 1945. The M24 had weaker armor, otherwise it may have been undoubtedly better than the T-50. Still, the difference of 4 years of war had a big impact.

It seems that the most important thing was to correctly determine the size, weight and layout of the [medium] tank. The rest could already be adjusted to them. In case of unsuccessful choice of size/weight/layout, no technical measures led to the optimum. In my humble opinion, the Soviets did it best. But, I repeat, the concept alone did not make the tank perfect or the best - low technological level could spoil even the best concept.

 

[Shortround6]

The Challenger was not a poor tank. Not wonderful but an excellent support for Cromwells and easier to fight than a Firefly not to mention having similar maintenance systems to the Cromwells, being a stretched Cromwell.

It certainly was not a good tank. It was an OK tank. Yes it may have been better than the bodged together Firefly. They still hadn't come up with cupola for the commander. There was no stowage for ammo in the turret (?), there was in the turret basket. A number of rounds were stowed sort of behind where the bow gunner would have sat, had there been a bow gunner. How much this stowage intruded into that area I don't know. This may have been the idea for the 2nd loader (?), getting the ammo from stowage up to where the primary loaded stood? Armor was thinner than the Cromwell. Just 40mm on the turret side and that was plumb vertical. Rate of fire was???

I admit that the Charioteer suggests that they could have simply used normal Cromwells adapted to a new turret as the Charioteer took the 20 Pounder and was tested successfully with the same 105mm L7 gun as is going into the new USA support tank today. Before anyone says so, yes, I am aware that the Charioteer was classed as a self propelled anti tank vehicle not a tank given the thin turret armour.

Charioteer had a few other issues aside from thin armor. One was the 25 rounds of main gun ammo. Another was that it didn't often operate as a "tank". Originally designed for a 3 man crew, commander/gunner, loader/radio operator, driver. A 4th man was added who rode in the bow gunners seat. In action the commander dismounted to observer the fall of shot and correct aim and the 4th man got from his seat on the left front of the hull to the gunner position in right side of the turret.
I don't know if the commander dismounted because of the muzzle blast kicking up too much dust, dirt, debris and smoke or if the tank moved under recoil enough to keep the gunner looking through his sight to observe the fall of the shot. It seems that the much heavier Centurion did not have that problem

edit: A Centurian had + 20, -10 degrees of elevation. The Charioteer had +10,-5 degrees according to one source. Other sources may differ?

Yes the 17pdr kicks a lot less and probably would not have that problem. On a standard Cromwell hull you are going to have an ammo storage problem though.

 

[Frog]

It certainly was not a good tank. It was an OK tank. Yes it may have been better than the bodged together Firefly. They still hadn't come up with cupola for the commander. There was no stowage for ammo in the turret (?), there was in the turret basket. A number of rounds were stowed sort of behind where the bow gunner would have sat, had there been a bow gunner. How much this stowage intruded into that area I don't know. This may have been the idea for the 2nd loader (?), getting the ammo from stowage up to where the primary loaded stood? Armor was thinner than the Cromwell. Just 40mm on the turret side and that was plumb vertical. Rate of fire was???

Charioteer had a few other issues aside from thin armor. One was the 25 rounds of main gun ammo. Another was that it didn't often operate as a "tank". Originally designed for a 3 man crew, commander/gunner, loader/radio operator, driver a 4th man was added who rode in the bow gunners seat. In action the commander dismounted to observer the fall of shot and correct aim and the 4th man got from his seat on the left front of the hull to the gunner position in right side of the turret.
I don't know if the commander dismounted because of the muzzle blast kicking up too much dust, dirt, debris and smoke or if the tank moved under recoil enough to keep the gunner looking through his sight to observe the fall of the shot. It seems that the much heavier Centurion did not have that problem

Yes the 17pdr kicks a lot less and probably would not have that problem. On a standard Cromwell hull you are going to have an ammo storage problem though.

By some historical irony, the first tank that a Centurion destroyed in Korea was its forerunner, a Cromwell captured by the Chinese.

 

[Elan Vital]

The job of the French tank gun (as it was the case with other people's tank guns) of 47mm was to outperform the armor protection of the enemy tanks. In that, it was more than suitable for the job.
It was also better than the 37-40mm guns of the day wrt. the HE performance.

True but the French 47mm had very little stretch. Most other tanks didn't have much stretch either. Higher velocity guns are easier to hit with at 600-1000 meters range. Remember that the projectile will drop 16ft (4.88 m) in it's first second of flight. yes you set up the gun so it hits a little high in the first 200-400meters so you can still hit in the last parts of the 1st second or even the first 1/10 or 2nd tenth of the 2nd second of flight. The projectile will fall 48ft (14.63m) in the 2nd second of flight.
French were also loading 37mm guns of differing abilities in a lot more tanks per month than they were loading 47mm guns into. They were certainly using more of the HV (700ms) 37mm guns in the last few months though.

I think the tank "powerful 37mm" (the SA38, powerful being one of the designations for it) and tank 47 are best assessed within their very particular use-cases, e.g employment in quite small 1-man turrets with emphasis on short ammunition and thus low overall power to be remotely easy to handle. With the 37 being constrained to boot by the requirement to fit the existing APX-R turret with minimal modifications (mask change pretty much). When that restriction could be lifted, you could fit bigger in a modified (Romanian 45mm conversion) or new (second generation French light tank turrets with the 47mm tank gun), even within the same turret ring (or rather same standard hull roof opening which the 2nd gen light tank turrets could fit).

Once you allow 2 or 3-man turrets, it becomes much easier to accomodate a more powerful gun from day one.

Admittedly, the merits of the tank 47mm were still well exploited: the Czech LT vz.35 and 38 also started with 1-man turrets in Czech service, with apparently somewhat larger turret rings, but only had 37mm guns below 800 m/s. While the analogous Italian 47mm L32 used much more dated uncapped APHE and was mounted on larger 2-man turrets which could otherwise probably have used something more powerful, as indicated by the use of the 47 L40 in the M15.

I do believe however that all these sub 700 m/s 47 and sub-800 m/s 37 with sometimes uncapped/APHE ammo were only acceptable precisely because a lot of tank building nations used excessively light armour even when more was possible or could have been designed for while keeping acceptable mobility, weight and reliability. Eg, the French tank 47 and 37 would have become really limited had France held and fought uparmored German tanks of late 1940/41. But when one accounts for what Britain or the Germans could reasonably have designed in the late 30s*, it is a stroke of luck that these guns found a favourable environment.

*And it is also why the sometimes touted merits of "heavy armor and powerful guns" of French tanks were highly circumstancial. In another world, the compromises they made would have been even less warranted.

 

[tomo pauk]

I do believe however that all these sub 700 m/s 47 and sub-800 m/s 37 with sometimes uncapped/APHE ammo were only acceptable precisely because a lot of tank building nations used excessively light armour even when more was possible or could have been designed for while keeping acceptable mobility, weight and reliability. Eg, the French tank 47 and 37 would have become really limited had France held and fought uparmored German tanks of late 1940/41. But when one accounts for what Britain or the Germans could reasonably have designed in the late 30s*, it is a stroke of luck that these guns found a favourable environment.

I'd say that it might be reasonable to expect that French, had they survived in a good shape by spring/summer of 1941, would've been introducing the better ammo for their guns, as well as the better guns. It is not a long shot that the spin-off of the 47mm ATG would've found it's place on the tanks and/or other AFVs. There are still the towed 47mm ATGs for the Germans to take into account, as well as the 75mm guns turned into AT guns.
France surviving into 1941 also means the 6pdr is available for the British.

There is also a question of how many Pz-IIIs and -IVs would've Germans had for Spring/Summer of 1941 if the high-intensity combat went through the 2nd half of 1940 and into 1941.

 

[Elan Vital]

I'd say that it might be reasonable to expect that French, had they survived in a good shape by spring/summer of 1941, would've been introducing the better ammo for their guns, as well as the better guns. It is not a long shot that the spin-off of the 47mm ATG would've found it's place on the tanks and/or other AFVs. There are still the towed 47mm ATGs for the Germans to take into account, as well as the 75mm guns turned into AT guns.
France surviving into 1941 also means the 6pdr is available for the British.

There is also a question of how many Pz-IIIs and -IVs would've Germans had for Spring/Summer of 1941 if the high-intensity combat went through the 2nd half of 1940 and into 1941.

It is true, though in the case of the tank-mounted long 47, I remain unsure how long it would have taken the French to notice the urgency (sufficient number of uparmored tanks encountered) and to implement it. While it can be reasonably rushed in 1941 on the Somua (see IRL FCM concept in 1942) and Char B family (apply B40 setup on B1 Ter to minimize deployment time and risk*), even the future light tanks are a fundamental difficulty. If it only followed the intended schedule, you would only see it in early 1942 on the battle tank.

Back in 1938, the tank 47 was expected to benefit from research on 37mm ammo. Maybe the documents I am going to see in January(pertaining to ammunition and ballistic research) will tell more. Strictly speaking, French guns usually ran on 240 MPa pressure so there is room for a hot loading while retaining acceptable barrel lives. But projectile side, I'm not sure how much they can improve on an APC with already modern shape and materials (BC will not help as the potential penetration distance is very short) if they were looking at full caliber solutions (APCR and APDS were not the go-to solutions at the time in the French army).

*Or 75mm turret as per late B40

 

[tomo pauk]

It is true, though in the case of the tank-mounted long 47, I remain unsure how long it would have taken the French to notice the urgency (sufficient number of uparmored tanks encountered) and to implement it. While it can be reasonably rushed in 1941 on the Somua (see IRL FCM concept in 1942) and Char B family (apply B40 setup on B1 Ter to minimize deployment time and risk), even the future light tanks are a fundamental difficulty.

French can play it safe: seen that both them and the British are fielding the very well armored tanks, it is only to be expected that Germans will up the armor protection of their stuff. Germans might've done that already in 1940, seeing that their tanks are vulnerable basically to anything with "AT" suffix in the Entente arsenal.

Back in 1938, the tank 47 was expected to benefit from research on 37mm ammo. Maybe the documents I am going to see in January(pertaining to ammunition and ballistic research) will tell more. Strictly speaking, French guns usually ran on 240 MPa pressure so there is room for a hot loading while retaining acceptable barrel lives. But projectile side, I'm not sure how much they can improve on an APC with already modern shape and materials (BC will not help as the potential penetration distance is very short) if they were looking at full caliber solutions (APCR and APDS were not the go-to solutions at the time in the French army).

The APCR-ish ammo was developed for the short 37mm already by 1935 (at least the ammo was called Mlle 1935), and was, for example, exported to Poland.
Brandt company was working with the APDS ammo before France fell, ditto with the squeeze-bore stuff.

Experimenting with the hotter loading for all the guns involved should've been a really low-hanging fruit.

 

[EwenS]

It certainly was not a good tank. It was an OK tank. Yes it may have been better than the bodged together Firefly. They still hadn't come up with cupola for the commander. There was no stowage for ammo in the turret (?), there was in the turret basket. A number of rounds were stowed sort of behind where the bow gunner would have sat, had there been a bow gunner. How much this stowage intruded into that area I don't know. This may have been the idea for the 2nd loader (?), getting the ammo from stowage up to where the primary loaded stood? Armor was thinner than the Cromwell. Just 40mm on the turret side and that was plumb vertical. Rate of fire was???

Why is having no ammunition in the turret a bad idea for Challenger? It was considered an improvement in the Sherman.

Look at the Sherman. Initial ammunition stowage. Initial "dry storage" layout.

https://www.theshermantank.com/wp-content/uploads/M4A4-small-hatch-storage-1.png

They quickly found that stowage above track level was vulnerable to AT guns and had to weld additional armour to the hull exterior to protect it. The above track ammo storage was the main cause of early Sherman losses, not petrol fires. Kits were manufactured to retrofit to earlier production vehicles.

Then we have Sherman Gen 2 produced from the early 1944.
"The real big change in Sherman storage came when the hull changed from the small hatch to large hatch configuration, though all the late model M4A2 tanks with large hatch hulls and 75mm turrets still got the dry ammo storage setup with add-on sponson armor [all bar about 200 of these for the USMC went as Lend Lease to the USSR] The other exceptions are the M4 and M4A3 105 tanks, they had their on dry storage setup. [meant to be support tanks] The M4 Composite hull tanks with large hatch hulls also kept the dry storage layout [production of these only ran Aug 1943 to Jan 1944 with 1,976 produced]. So, the M4A1 (76)W, M4A2 (76)W, the M4A3(75)W, The M4A3 (76)W tanks all had the improved wet ammo racks. This change included moving all main gun ammo into the floor of the hull under the turret. These ammo racks were also surrounded by water filled jackets. Early production wet tanks retained the turret basket, and had hatches that could be opened to access the hull ammo racks, later they only installed a half basket, and eventually removed the basket floor entirely."

Ammo Storage | The Sherman Tank Site

www.theshermantank.com

A30 Challenger had stowage for 48 rounds. Only 2 rounds were stowed horizontally above track level (just behind driver's position). 4x3 rounds around turret basket stowed vertically. 3 rounds left side rear of fighting compartment stowed vertically. 18 rounds stowed horizontally next to driver. 6 rounds stowed vertically between driver & 18 round bin. 5 rounds stowed vertically on lhs of fighting compartment behind bin and a final 2 under the gun breech.

Extracting some of the rounds was difficult, just as it was in the later Shermans. Trials of an early vehicle showed about 6rpm was possible.

Unlike most tanks where the turret sat on a ring on the upper hull, Challengers turret was supported from beneath by a heavy basket that sat on a ball bearing arrangement on the vehicle floor. There was then a series of guides around upper part of the basket to keep it in place. So there was no room under the turret in Challenger to stow ammunition.

As for its turret armour in early vehicles the turret front was 63mm with the rest being 40mm. BUT from vehicle 41 (of the 200 produced) the front turret plate was increased to 102mm (July 1944 production onwards). Then from Nov 1944 (around vehicle 110) Challenger was produced with an applique armour kit fitted. This increased the thickness of the turret front side plates, driver's visor plate and turret box front plate to approx 89mm and the nose plate to 82.5mm (sloped at 20 degrees). An additional 10mm was welded to the turret box bottom plate increasing it to 18mm.

 

[SaparotRob]

I never even heard of the T-50 before. I guess it wasn't involved in any fleet actions.

 

[Shortround6]

I'd say that it might be reasonable to expect that French, had they survived in a good shape by spring/summer of 1941, would've been introducing the better ammo for their guns, as well as the better guns. It is not a long shot that the spin-off of the 47mm ATG would've found it's place on the tanks and/or other AFVs. There are still the towed 47mm ATGs for the Germans to take into account, as well as the 75mm guns turned into AT guns.
France surviving into 1941 also means the 6pdr is available for the British.

There is also a question of how many Pz-IIIs and -IVs would've Germans had for Spring/Summer of 1941 if the high-intensity combat went through the 2nd half of 1940 and into 1941.

We have "what if" and we have historical.
For historical on the Germans side we have the Short 50mm being worked on since 1938. I don't know the month but other people may. The long 50mm also dates to some time in 1938. I don't know the overlap. As is well known the Germans had sized the MK III to take at least the short 50mm if not the long one. No redesign needed.
MK IIIs were made in one factory, the A, B, C, D were all made by Diamler-Benz and production was complete by June 1938 (?) 70 tanks total.
The Germans built 96 (?) of the E model and that took from Dec 1938 to Oct 1939. Henschel and MAN had joined in. Now things get complicated.
The Germans built 435 (?) of the Fs from Sept 1939 to July 1940 and had 5 factories, Alkett And Famo had joined in.
Weight had also gone from 16 tons on the old D to 19.8 tons on the F. According to one source the last 100 (?) got the 50mm guns as built, other sources may differ. Most sources say none of the 50mm armed tanks saw combat during the fighting. The Gs start being produced in April 1940 and 600 are built, ending in Feb 1940, except that Wegmann has joined the number of factories. About 50 tanks were completed with the 37mm gun, the rest got the 50mm as built. From August 1940 the older tanks started getting refitted with the 50mm guns and new mantlets and with extra 30mm armor plates on the front and rear of hulls. Photos show tanks with the new guns without the extra plates.
How fast the upgrades would have been done if the French were still fighting? Would factory production been increased?
The H model showed up in Oct 1940. This was supposed to have been the first model with the 50mm short gun but things had changed due the French campaign. While the extra 30mm plates bolted to the hull may not have been in the 1939 order (takes a while from paper order to actual tanks) most/all of the production tanks had them. Perhaps my old book is wrong but there seems to be a large group of factories working on MK IIIs. D-B might not have built any of the Hs or it may be a misprint, at any rate MNH has joined in and for the Js (March 1941?) there are 7 factories. Js get single piece 50mm hull plates (still 30mm front turrets) and tanks are now 21.5-21.8 tons.

If the French had hung on for another year would it have take the Germans until Dec 1941 to sling the long 50mm into a MK III? They had to towed gun (in small numbers) in the fall of 1940.

This has been a bit long but it helps show that the Germans, while not reacting to the French tanks specifically (no panic mounting of large guns in tanks that did not fit doctrine) an and that the Germans had better understanding of what they wanted the tanks to do. Not saying they did get them to do everything they wanted. The short 50mm would have at least given them equality with the 47mm SA 35 gun. Trying to up grade French tanks to the 47mm AT gun is possible (maybe?) but since this gun is very close to the German long 50mm in size, weight and power trying to stick in in existing 1 or possible two man turrets is going to be very difficult. Using the British trick with the 57mm of leaving one man out of a 3 man crew is not going to work.
Germans had option of sticking the long 50mm in the MK IV, HE capability would stink but if you needed more AT gun tanks in a hurry at leas the gun fits. You also can story more ammo than the MK III.
Of note for possible upgrades of other tanks the almost 6 tons of increase weight in the MK III (over 40%) might give people pause. This is for a tank that was designed to hold a larger gun than the 16 ton model got.

Germans chances of invading Russia in 1941 if the French hold out for even 6 months are pretty dismal. But the Germans don't have pretty drawings or a few prototypes in May of
1940. They have multiple factories (small ones?) tooling to manufacture the guns and tanks to start deliveries in July/Aug.
The French have NOT solved the vision problems (more/better periscopes and cupolas) or the manufacture of radios or the tactics/doctrine.

 

[tomo pauk]

This has been a bit long but it helps show that the Germans, while not reacting to the French tanks specifically (no panic mounting of large guns in tanks that did not fit doctrine) an and that the Germans had better understanding of what they wanted the tanks to do. Not saying they did get them to do everything they wanted. The short 50mm would have at least given them equality with the 47mm SA 35 gun. Trying to up grade French tanks to the 47mm AT gun is possible (maybe?) but since this gun is very close to the German long 50mm in size, weight and power trying to stick in in existing 1 or possible two man turrets is going to be very difficult. Using the British trick with the 57mm of leaving one man out of a 3 man crew is not going to work.

There is no doubt that Germans have had the best tank doctrine in the world in that time. At least the Pz-III and -IV were a product of that doctrine, with the 3-men turret crews and balanced (if not actually great) guns' outfit.
The upgrades to the tanker 47mm ammo are already suggested in this thread. Yes, even better if the bigger turrets are in the pipeline, since these will allow both for at least two men in them, as well as something bigger gun to be installed.

Germans chances of invading Russia in 1941 if the French hold out for even 6 months are pretty dismal.

Agreed.

But the Germans don't have pretty drawings or a few prototypes in May of
1940. They have multiple factories (small ones?) tooling to manufacture the guns and tanks to start deliveries in July/Aug.
The French have NOT solved the vision problems (more/better periscopes and cupolas) or the manufacture of radios or the tactics/doctrine.

Both countries, and British with them, will make every improvement to their tanks that is feasible to do during the Summer and Autumn of 1940 (plus during the Winter etc). Germans will try to up-gun and up-armor their stuff, while French will try to do the same, as well as to introduce the better turrets if possible. Yes, French will also try to modify their doctrine and tactics according to the lessons learned, and sometimes they will employ the 'throw it at the wall and see what sticks' principle.

 

[Shortround6]

We worry about the guns and the penetration. We don't worry enough about rates of fire and even more rates of engagement. How many targets can tank and crew engage (service in modern speak) per minute.
This where the vision and 3 man turrets really pull ahead. I just a video by the Chieftain about the early T-34 and an engagement where a 37mm Pak gun shot a T-34 23 times before getting a hit on the turret ring and jamming the turret. The Chieftain is practically shaking his head at the idea of a tank getting hit 22 times before the critical hit and not knowing where the AT gun was hiding. If commander had ever seen the little gun one or two 76mm HE shells would have put an end to whole show very quickly.

Tank design (and doctrine) is a fine balancing act. The British had fallen off the wire and landed in the net many times but kept insisting that with a little more time/practice they would show that they were right. In 1936 Percy Hobart had written to Basil Liddell Hart about a new director of military training with this comment. "I hear the new DMT thinks tanks ought to halt to shoot! God! I thought we had killed and disproved the heresy ten years ago."
Percy Hobart was the General who trained and formed the 7th Armored division in the Mid east in the late 30s. It wasn't until a lot of battles showed the fallacy that things changed and tankers were instructed to halt before firing.
But it was not enough to tell the tankers to halt before firing. The doctrine had resulted in small, easy to elevate guns with good balance (located further back in the turret) and simple sights with low magnification (wide field of view) and no elevation mechanism to hold the gun in place after each shot making every repeat shot a sort of first shot, a lot harder to walk the shots onto a distance target. Couple that with the commander having a choice of sticking his head of the hatch and using hand held binoculars or or using the standard periscope to try to spot the tracer or fall of shot and things got ugly real quick. Using the commander as the loader and having him shove rounds in the Breech instead of spotting the fall of shot or spotting the fall of shot and then reloading the gun slowed the "book" rate of fire drastically. All of these failings/problems start with the doctrine of firing on the move. Until you change the doctrine not only for the crews in the tanks but in the tank design committees you are going to get tanks that won't allow the crew to do what is needed.
And we haven't even gotten into hi velocity vs low Velocity or HE vs AP or proper use of machine guns

 

[Shortround6]

Both countries, and British with them, will make every improvement to their tanks that is feasible to do during the Summer and Autumn of 1940 (plus during the Winter etc). Germans will try to up-gun and up-armor their stuff, while French will try to do the same, as well as to introduce the better turrets if possible. Yes, French will also try to modify their doctrine and tactics according to the lessons learned, and sometimes they will employ the 'throw it at the wall and see what sticks' principle.

My point is that the Germans were actually in the process of installing at least the short 50mm in the MK IIIs before they invaded France. Things may have gotten more urgent. The French plans were a number of months behind. The French had also shown a tendency to not be able to turn ideas and/or prototypes into service hardware (in use by actual army units) in a timely fashion for most of the 1930s. The French had actually been ahead of many other armies as far as some ideas go (the 75mm gun in the Char B was a start, not good one but a start) and did a lot of work with armor casting and thick armor and heavy tanks in general. The S 35 weighed, in 1935, about what the MK III did in the winter of 1939/40. It had much thicker armor. It also had a 190 hp engine. The cast turret was innovative, it was also complex to make. Germans were welding turrets together out of lots of small plates.
The French had a lot of plans, how soon things would have come together is a real question. The French were planning improved S 35s (and other tanks) even before the war started in 1939. They had cast one or more hulls in Nov 1939 but were still waiting for turrets (and new 230hp engines ) when the war ended in June 1940. The change over was supposed to have been made with hull no 451, they only got to hull no 440 or one/two more. The last order for the S-35 (bring total ordered to 450 tanks) had been placed in 1938. In Sept 1939 they ordered 50 more tanks and and later they added 324 but none of these two orders ever saw a completed tank, How far any components got may be different.
S 35 was so expensive that the French ordered hundreds of H 35s to 'supplement' it. They French could have had plans, and ideas, and drawings and prototypes of guns, turrets, and even a few hulls. What they did not have in the summer of 1940 was needed plants/factories to turn any of the plans into needed numbers. Germans in 1939 were planning on building well over 1000 MK IIIs. Now they only had about 98 for the attack on Poland but they were working on bringing in those other 6 factories besides DB in 1939, it just takes time. Time that France did not have. Trying to put a two man turret on the S35 with the 47mm SA 35 gun in the summer or fall/winter of 1940 is too little, too late.
Just found this on Wiki in the entry for the Hotchkiss H35 so take it as you will.
" It was decided to concentrate most Allied production capacity for light tanks into the manufacture of a single type, and the Hotchkiss tank was chosen as it had the necessary mobility to be of use in the many armoured divisions the Entente planned to raise for the expected decisive summer offensive of 1941. To this end British and Portuguese heavy industry had to assist in producing the cast armour sections. It was hoped to increase production to 300 a month in October 1940, and even 500 a month from March 1941, the sections of 75 of which to be provided by Britain in exchange for a monthly delivery of nine Char B1s. This can be compared to the planned production of the R40: 120 per month, reflecting the little importance now attached to infantry support."

Granted this was before they had any real experience with tank combat in April/May of 1940 and plans would have/should have been revised. 500 H-39s a month is terrible waste of industrial resources and tank crewmen.

 

[tomo pauk]

S 35 was so expensive that the French ordered hundreds of H 35s to 'supplement' it. They French could have had plans, and ideas, and drawings and prototypes of guns, turrets, and even a few hulls. What they did not have in the summer of 1940 was needed plants/factories to turn any of the plans into needed numbers.

I'd guess that two H35s will cost at least as much as one S35, while needing double the number of trained crew
440 of S35 produced before mid 1940 is still very good. Too bad that French didn't doubled-up on the S35, foregoing the H35 all together, for yet another 600+- of the S35s instead of 1200+- of H35s.
French tank production, in numbers and let alone in tonnage was better than what Germans were doing, pointing out that they in fact that they have had the plants/factories to make stuff. Unfortunately, best of the production capacity was used up for making the under 12 ton tanks crewed by two men each.

Germans in 1939 were planning on building well over 1000 MK IIIs. Now they only had about 98 for the attack on Poland but they were working on bringing in those other 6 factories besides DB in 1939, it just takes time. Time that France did not have. Trying to put a two man turret on the S35 with the 47mm SA 35 gun in the summer or fall/winter of 1940 is too little, too late.

France didn't have had the time because they were defeated by Germany. As it can be seen, production of the serious tanks in Germany was also not roses and unicorns.
If the S35 can have a 2-men turret in the operative tanks in summer of 1940, that is a major boon for them. Having that in, say, October is indeed too late for 1940.

The French had actually been ahead of many other armies as far as some ideas go (the 75mm gun in the Char B was a start, not good one but a start) and did a lot of work with armor casting and thick armor and heavy tanks in general.

The 75mm gun on the Char B was a good start. An excellent start when compared to what the other people were installing in their tanks in the second half of the 1930s.

 

[Elan Vital]

Both countries, and British with them, will make every improvement to their tanks that is feasible to do during the Summer and Autumn of 1940 (plus during the Winter etc). Germans will try to up-gun and up-armor their stuff, while French will try to do the same, as well as to introduce the better turrets if possible.

I'd guess that two H35s will cost at least as much as one S35, while needing double the number of trained crew
440 of S35 produced before mid 1940 is still very good. Too bad that French didn't doubled-up on the S35, foregoing the H35 all together, for yet another 600+- of the S35s instead of 1200+- of H35s.
French tank production, in numbers and let alone in tonnage was better than what Germans were doing, pointing out that they in fact that they have had the plants/factories to make stuff. Unfortunately, best of the production capacity was used up for making the under 12 ton tanks crewed by two men each.



France didn't have had the time because they were defeated by Germany. As it can be seen, production of the serious tanks in Germany was also not roses and unicorns.
If the S35 can have a 2-men turret in the operative tanks in summer of 1940, that is a major boon for them. Having that in, say, October is indeed too late for 1940.



The 75mm gun on the Char B was a good start. An excellent start when compared to what the other people were installing in their tanks in the second half of the 1930s.

Pretty much on point for the price calculation (it's approx 2 H39s for one S35), with the required number of personnel being 33% (but only radio operators), if you look at number of trained crew it is indeed double.

Some of the documents I'm seeing in January discuss orders of automobile vehicles in 1939/40 and the industrial situation in late 1938 and late 1939, so they might clarify things a little bit (and experimental APX "materiel" for tanks in wartime which might clarify stuff about ongoing work re gun integration).

The case of the Somua remains a mistery because even as of 1940, the mobilization orders only go for 36/month while required monthly production ballooned for other types (even B1's mobilization orders increased to 100/month just after the declaration of war when it was realized that the originally envisionned 50/month would not suffice). I know one document I intend to see will at least clarify the prewar situation (it was suggested to procure more numerous times). The fact that it was only required for armored divisions isn't a sufficient reason since part of the Infantry requirement for Hotchkisses was as a stopgap in the DCRs pending the arrival of enough B1s, not just as a light infantry tank for the independent infantry support tank battalions.

The 500/month figure for H39 was never seriously considered. What happened at declaration of war was that the mobilization capacity for Renaults was unchanged (120/month) while that of the Hotchkiss was sharply increased upon realization of the sheer needs for tanks and the fact it was the simplest tank to build. In fact Hotchkiss was even told not to acquire the tooling for 600/month since it would be useless (they would face bottlenecks elsewhere and the Army didn't want that level of priority).

Turrets were the one thing meant to change significantly in the Summer 40-Spring 41 period, while everything else was for 1941 instead*.
The trend was towards almost no castings or only for small pieces, and instead welded, bent and pressed assemblies (ARL 2, 37 FCM, ARL 5).
For the Somuas, we know that industrialization of the ARL 2 C (Cavalry) turrets was ongoing in May and their deployment pretty much imminent (July/October). The matter was under investigation before the battle for the remaining B1 Bis, but it's not known if industrialization of the ARL 2 and modified roof plates was ongoing for this type.

The elusive ARL 5 was already envisionned for production as early as April 1940, but unfortunately, no documents can say where the industry was in May. A prototype was running.

All of these 2nd generation turrets share a simpler construction (reduced use of castings) as the most defining characteristic. Vision is improved insofar as the 2 PPL 160 episcopes (1 per side) and the rotating cupola with 3 vision slits and one binocular sight from the APX-4 are replaced with 3 PPL 160 (one in the rear door now) and a fixed integral cupola with a panoramic Gundlach periscope and 3 PPL on the ARL 2. Vision is always a particular subject for 1-man turrets however as the cupola is de facto the main observation post. ARL 5 is unknown other than the fac it has a fixed cupola.

ARL 2 at least is also tied to a new safer turret ring, and an improved electric traverse system (no clue yet if it faster or better for the actual traversing part, however it no longer uses the batteries so it was more convenient for battery management). It also included a ready supply of ammo for initial engagements unlike the APX-4.
In all cases, increased protection was solely the result of switching to rolled plate and potential improvements in shape. In the case of the ARL 2, you can somewhat cheat because it was a modular type prepared for 40 to 70/75mm thickness, so you could slap the thicker types on a B1 Bis and Somua even if you didn't change the hull armor (weight penalty: 700 kg tops on the B1 Bis, 1200 on the Somua but you go from 40 to 70mm).

APX-R (light tank turret) with 60mm of armor was once a proposal for an armored car, but you would need a new casting and it is apparent that it was to be replaced anyway.

The lessons' learned report after the battle exactly adresses Short's points (2 crew members at least, albeit still not mandatory on the light tanks, hybrid cupolas with features from the Germans AND 2nd gen French designs, gun mounts modified in favor of setups for shorter turrets like the Germans).

*the more appropriate summary for Summer 1940 and Spring 41 is
- generalization of long 37 on the light tanks
- continued increase in monthly production
- turret swaps
- S35-->S40 (mobility/quality of life upgrade)
- reliability/durability mods on B1 Bis plus increased fuel capacity
- industrialization and generalization of light tank radios and intercoms for the battle tanks at least
- major/minor suspension changes on the lights and potentiallybelly upgrade against AT mines (R35-->R40, new track for Hotchkiss)

Ironically, the French were spending 1940 precisely working on the areas we criticize them the most on, while ignoring those we praise them the most for. And it is also the exact opposite of the areas the Germans worked on.

Indeed, the book is overdue.