Medium tanks proposals for 1943

[tomo pauk]

Currently, I love to speak about tanks, so bear with me

What kind of a tank, weighting about 30 tons (+- 10%, so it's 27-33 tons actually), would be well suited for the tank-producing nations their allies? The tank should enter production from Jan 1943, serving well into 1944 as-is, and even later with some plausible upgrades. The historically available engines, guns, transmissions, suspensions etc. are the main ingredients. Suitability for the mass production is one of key points, so no fancy stuff should find it's place here. The ability to serve well as a platform for other tasks weapons is another major plus.
Hopefully, this would not steer into a contest between real ww2 tanks

 

[davebender]

USA. Sherman with 76mm main gun and (hopefully) an improved HE shell.
Soviet Union. T-34/76 with 3 man turret.
.....T-34/85 as soon as possible. However production disruptions from Germany seizing Kharkov will probably prevent an earlier introduction.
Britain. Don't build any. Mooch Sherman tanks from the USA Lend-Lease program.

Germany. Build a vehicle I will refer to as a "Panther Lite". Or perhaps "Panzer 4.5".
- 32 ton VK3001 chassis with Schachtellaufwerk suspension.
- Upper hull and turret similiar to Panther tank but scaled down to fit the smaller chassis.
- Main gun will be the 7.5cm/48.
- 60mm sloped armor.

The historical Panther tank was an excellent vehicle but designing and debugging a reliable powertrain for the 45 ton vehicle was a technical challenge. I think a 32 ton Panther Lite could enter service up to a year sooner and it's more then adequate for WWII. Like the Panther this tank would be designed for mass production. So even though it's 50% heavier then a Panzer IV it should be less expensive to produce. Build them like hot rolls as the only German tank.

The historical Panther program could proceed in parallel. However it doesn't enter production until 1944 (i.e. when bugs are fixed) and main gun should be the 8.8cm/71. The Panther would provide a heavyweight punch vs late war tanks such as the Joseph Stalin series.

 

[Vincenzo]

a T-34 with a Pz IV turret

 

[davebender]

I've always thought Germany should build such a vehicle after capturing the Kharkov T-34 plant. Vehicle chassis and many other components would be locally produced. Import turrets, radios, intercom system and various other bits from Germany for incorporation into the completed tank.

 

[yulzari]

For British forces simply bring forward the Comet and include a sloping glacis plate losing the bow gun. The 77mm was a 17 pounder 'lite' so was within industrial capacity but you have to make this decision in 1940 to get it in the field in numbers in 1943. Shermans were welcome but you cant simply decide to have UK factories twiddling their thumbs when they could be making thousands of tanks.

 

[tomo pauk]

For Germans, I'm a fan of the 'big Pz-III'. Profile being almost the same, but incorporating sloping armor, to keep Soviet 76,2mm AP projectiles out, (say, 300m front, 500m side attack), as well as US 75mm and British 6pdr. The tank need to be compact, incorporating either L48 or L70 7,5cm cannon*. If the Germans adopt an 'all-back' transmission, tank can be even more compact.

Soviets tried with T-43, a T-34-76 lookalike, but with torsion bars suspension and heavier armor, up to 90mm, being sloped. Their medium tank need to keep the projectiles from 7,5cm PaK, Pz-IVG/H and StuG-IIIF/G out, from frontal attacks that are 300m away and more, 500m from side. Cannons of 85mm, 76,2mm (from the AAA piece), or a combo of 'regular' 76,2mm + 57mm (2:1 ratio maybe).

*the 88 L56 would be great

 

[davebender]

I'm all for that.

The original 1935 Panzer III specifications called for a 15 ton tank with a 5cm main gun. If the original specifications had called for a 25 ton tank with a 7.5cm high velocity cannon there's no reason to think it couldn't be in mass production by 1940. By starting with a 25 ton chassis you've got more room for future improvements such as sloped armor. They early 1940s version might look something like this and weigh about 30 tons:

Panzerkampfwagen III/IV Einheitsfahrgestell

 

[Shortround6]

A lot of early specifications called for things that could not be done in reality. Some of the weight limits were driven by the desire to use existing trucks or trailers, to allow for "strategic mobility" in regards to existing road and bridge networks or for "tactical mobility" in regards to engineer/pioneer equipment like floating bridges or rafts/ferries for crossing rivers. In many cases too much of the actual military requirement of the vehicle was lost trying to meet unrealistic weight limits. Too thin armor was often the result. Or small turrets in a effort to keep size down and keep armor thickness up. Transmission and steering gear weights were often underestimated as were the weights for an adequate suspension. They did learn quickly and by 1939-40 requirements were usually a bit more realistic. Changing requirements in the middle of the design process caused a lot of problems though.

 

[tomo pauk]

For the Brits USA, the armor requirements would be same as for the Soviets. Mobility would include a Meteor, or Ford V engine (keeping a tank compact). American tank should either have it's drive set at back, or 'push' the drive shaft lower (for front drive), so the height is not that big. British have in 17pdr a great asset, just make the tank having the sponsons, maybe an 25pdr as a HE-oriented sidekick? Or an reduced load of propellant, to allow for a better HE shell for the 17pdr.
USA can install 76mm, with 105mm to help out (or the same modification as for 17pdr as above).

 

[davebender]

It's my understanding 26 tons was a typical weight limit for European roads and bridges during the 1930s. That's why I recommend 25 tons as the specification weight limit.

 

[Shortround6]

Tomo, please look at existing 25 ton tanks. Like the US M-41. Big guns, even big 75/76s, high mobility and good armor cannot co-exist even in 25 tons.

Armor protection good against the US 75mm gun as used in the Sherman that is 98-100% proof at 500yds has to be on the order of 80mm thick or a bit better. Tiger I scale. If you can slope the armor 60^ from the vertical you can cut the armor to around 30-35mm depending on projectile type but 40mm armor will weigh the same for the same height covered' so the weight savings may not be quite as much as you think.

You can only shrink a tank so much before it becomes too small and becomes too hard to work in. For instance the British managed to reduce the hull height of the Chieftain tank by reclining the driver, without doing that your hull height is some what fixed by the height of the seated driver. You also have a limit on the height of the tank from the inside of the floor to the turret roof if you want the loader to be able to handle large shells with efficiency. We also start to get into suspension choice here and width of the tank vs height and overall width of the tank vs the width of the hull.
If you use Christie suspension it takes up room in the hull sides, usually between an inner wall and outer wall but leaves the floor free. If you use a torsion bar suspension it allows for a wider hull but needs several inches of space and a false floor, adding to the height of the tank. Certain types of bogie suspension take up little internal volume, if any, but usually have ride or cross country speed issues. They may require a bit narrower hull for the same overall width as the torsion bar but again it depends on the exact bogie suspension type.
With the benefit of hind sight we have figured out what the ideal crew layout for a tank is, 4 men with the driver in the hull, centered if possible, and a turret crew with the gunner on the right, commander behind him and loader on the left. This works well for tanks using guns up to even the 120mm smoothbores but a tank using a conventional 120mm gun and full bore ammunition( NOT APDS or APDSFS ) may be better with two loaders.
Tanks using smaller, lighter ammunition have a bit more flexibility, the smaller the ammo the greater the flexibility.
The larger the round the more space is needed Behind the gun in order to load. And if you want to fire from hull down positions then the gun needs to depress about 10^, not only without hitting the turret roof but with enough room above and behind to fit the ammunition. Unless you resort to the Russian solution of the cold war in which the gun automatically elevates to a set angle after firing in order to load. Great for a small size tank but plays merry H**L with the rate of fire.

 

[tomo pauk]

Tomo, please look at existing 25 ton tanks. Like the US M-41. Big guns, even big 75/76s, high mobility and good armor cannot co-exist even in 25 tons.

The thread should cover 27-33 ton tanks
If you're reffering at my 'big Pz-III' idea, that includes only the general layout, not just a tad a modified historical Pz-III. The weight is ~50% greater than of Pz-III here, giving enough room for a decent tank.