ATL tank 1940

[Redbeard]

I was tied to the house for the weekend and utilised it by playing with MS Paint. I'm told that it is a very simple drawing programe, but it is also very easy to learn to use - and it ended up with an ATL tank which I hereby present: the K40

The tank is composed of technology and ideas that all were available for production in 1940, I've just combined them plus my ideas of "good looking", into THE IDEAL TANK of 1940 - at least until I've had your comments.

Basic data is on the cutaway drawing (one more drawing in next post), but the engine is the Soviet 500 hp diesel as in the T34 and KV1. The gun is an adaption of a 45 calibre naval AA gun. Many 75mm/3" 45-50 calibre AA guns with MVs from 650-800 m/s were in service in the interwar years (weighing 1-1,3 tons incl. breech, excl. cariage), so it ought to be possible to have a 75mm 800 m/s tankgun in serice by 1940 - if anybody saw the need. Turret ring is 2,20m, ought to be enough for later upgrading of gun (to 75mm cal. 60+). There is a coaxial mg to the left of the main gun and a heavy mg at the comamnders cupola for AA.

The sloped design was obvious once it was there, as the T34 proved. In some ways you could call my K40 a beefed up T34 incl. lots of 20/20 hingsight (three man turret, radios, commander cupola, vision blocks) etc.), but only technology avaliable by 1940.

I calculated the total armour weight to appr. 19 tons, which suprised me as low, as I consider the protection quite good. Incl. a generous alotment for armament, fuel and ammo (3,4 tons) that would leave 10 tons for the rest (engine, transmission, supsension tracks, equipment etc.) if a power to weght ratio similar to the Panther was to be achieved. If 15 tons is allowed "for the rest" the PtW ratio will similar to a Tiger I.

I have deleted the 5th crewmember and used his space in the front hull for ammo storage. Main fuel tank is between the engine and the turret basket.

Comments?

Regards

Steffen Redbeard

[Redbeard]

The second drawing as mentioned in the post above. Sadly they are distorted here, appearing too "tall" but I hope you get the meaning.

Regards

Steffen Redbeard

[The Dean]

That looks good are you going to be able to resolve the perspective issue? I take it Christie suspension?

[17inc]

Thats a nice tank you got there so whos building the UK USA or USSR . From the looks its a UK or US tank with that 50 cal.

[CalBear]

I would suggest an upgun to a 85-90mm/25 pounder. The guns were available, normally in an AAA carriage, however no one had thought to put one onto a tank

[LowLevelFunctionary]

It very much reminds me of the Panther - although I would presume this is somewhat intentional from the 'good looks' perspective?

[The Dean]

I like the idea of up gunning although I doubt if it would occur to anybody in 1940 that it would be necessary. If it was going to be done a good contender would be this

It is the 3.7in quick firing anti aircraft gun used by the British and Commonwealth forces. This replaced the earlier 3in gun which entered service in 1914. This model entered service in 1937 so it would have been available for use in 1940 for the K40.
As the Axis air threat diminished 3.7 AA batteries were converted for use in the field role in much the same manner as the very similar PAK 88. The gross weight of the gun was 8,392kg so with the mobile mounting removed it would not be a lot hevier than your 75mm.

[Stalker]

What would you do with the gun supports? You cannot simply put them into the turret. What is the total weight of the cannon? You see, tank guns must have certain weight limitations... That also means that you will be forced to design a new turret for the tank - they way Soviets did it for 85-mm Д-25Т for T-34/85 in 1943. That also may touch off the whole domino chain. The heavier turret may require a different chassis to be developed etc.

[Redbeard]

The suspension is torsion bar like in Pz III and most post WWII tanks. The Christie suspension takes up space in the hull sides limiting the turret ring, which again is paramount for how big a gun can be carried. I considered a M3/M4 type suspension, as it takes up no space inside the hull, but tyhe torsion bar gives a better ride and the double floor improves protection against mines. The intervals between torsion bars would be useful for ammo and fuel storage too.

I agree that the 3,7" or the US 90mm AA gun probably could be cramped into the turret. They both recoiled around 30" (76cm) and the distance from breech to turret ring with the 75mm/45 is 100cm. I just felt that having military shoppers realise a 75mm HV gun was necessary before 1940 was all that was allowed inside plausability (after all the Soviet planners went for a 75mm well before 1940). But a 3,7"/90mm would indeed be an option for a mid war upgrade. Anyway a 75mm going at 800 m/s would be an extremely powerful gun by 1940, piercing anything known for years to come and with a useful HE too.

A 25pdr or 105mm howitzer ought to be possible too, some M4s carried a 105mm turret mounted, but I think all planners pre 1940 would considder a 75mm HE more than enough. But then again, the Soviets stuffed a 152mm howitzer into a heightened KV1 turret (KV2).

I have had no specific nation in mind, but just tried a study of what would have been possible with combining available technology (letting 20/20 hingsight do the choosing).

It does look like a Panther and even more like a T34, any tank with sloping armour will, but I frankly think my mantlet and turret front is better than the Panther and the 3 man turret a big improvement over the T34, as is the general protection (on Panther level - three years ahead).

I don't know what to do why the distortion of the images, haven't experienced it before.

Regards

Steffen Redbeard

[Riain]

It seems too big for a prewar tank design. The design parameters for prewar tanks were set by the size of train flatbed cars and tunnel dimensions, as well as the wieght that army engineer bridges could bear, which was about 20tons in the late 30s. German railways were a bit wider than British railways, so German prewar tank designs are a bit bigger than Brit designs. Russian railways are wider again so the T34 starts with that as a design parameter advantage. Designs started during the war traded the strategic advantage of easy rail transport for the tactical advantage of lots of armour and big gun. But within these prewar parameters there is a lot of scope for improvement, getting to 1941-2 standards from the start with good design forsight.

[The Dean]

Originally Posted by Riain

It seems too big for a prewar tank design. The design parameters for prewar tanks were set by the size of train flatbed cars and tunnel dimensions, as well as the wieght that army engineer bridges could bear, which was about 20tons in the late 30s. German railways were a bit wider than British railways, so German prewar tank designs are a bit bigger than Brit designs. Russian railways are wider again so the T34 starts with that as a design parameter advantage. Designs started during the war traded the strategic advantage of easy rail transport for the tactical advantage of lots of armour and big gun. But within these prewar parameters there is a lot of scope for improvement, getting to 1941-2 standards from the start with good design forsight.

The Matilda II weighed in at 27 tons and was 2.6 metres wide so the size and weight of the K40 would not be an insurmountable problem.

[NapoleonXIV]

Damn

I can't even draw a child's airplane with MSPaint. You should write a tutorial or a Dummies book. Very good.

[Cockroach]

Damn good drawing. So which nation's use is it intended for?

I would suggest an upgun to a 85-90mm/25 pounder. The guns were available, normally in an AAA carriage, however no one had thought to put one onto a tank

25 pounder or a ~90mm Howziter may make sense for a close support variant but quite frankly a 75mm or 76mm high velocity gun will suffice against all tank prior to about 1942... and with sabots and HEAT rounds the main gun will remain effective until at least the early MBTs enter service (so mid 50s or so).

[Hendryk]

Great drawing. What is the width of the caterpillars?

[The Dean]

Originally Posted by CalBear

I would suggest an upgun to a 85-90mm/25 pounder. The guns were available, normally in an AAA carriage, however no one had thought to put one onto a tank

Not until the Pkw VI Tiger 1 appeared in 1942. In reply to Stalkers comments

Originally Posted by Stalker

What would you do with the gun supports? You cannot simply put them into the turret. What is the total weight of the cannon? You see, tank guns must have certain weight limitations... That also means that you will be forced to design a new turret for the tank - they way Soviets did it for 85-mm Д-25Т for T-34/85 in 1943. That also may touch off the whole domino chain. The heavier turret may require a different chassis to be developed etc.

These guns could be moved easily from the mobile mounting I displayed in my post http://www.alternatehistory.com/disc...10&postcount=7 and bolted to a fixed static mounting



as I have already pointed out the PAK 88 was taken off of its AA mounting and fitted in the Pkw VI & VII so there would have been no problem doing the same with the 3.7in QF. In my previous post I stated the gross weight of the gun and it was not much higher than the gun Redbeard proposed so removing it from the mobile platform would most likely mean it was no heavier than the 75mm originally proposed.
If you visit the Royal Armouries Museum at Fort Nelson you can see examples of the FLAK 88 and 3.7 QF displayed side by side and they are strikingly similar. If one could be used in this manner there is no reason that the other could not.
However in the first line of my original post I did state that I doubted anybody would see any requirement for a gun that large in 1940. Indeed it was late 1941 that a well known megalomaniac and proponent of unfeasibly heavily armoured and armed machines on land and afloat ordered the development of the Henschel VK 4501(H) alongside the Porsche VK 4501(P) the former of which became the Pkw VI.

[Redbeard]

Originally Posted by Stalker

What would you do with the gun supports? You cannot simply put them into the turret. What is the total weight of the cannon? You see, tank guns must have certain weight limitations... That also means that you will be forced to design a new turret for the tank - they way Soviets did it for 85-mm Д-25Т for T-34/85 in 1943. That also may touch off the whole domino chain. The heavier turret may require a different chassis to be developed etc.

The 75mm AA guns I looked at weighed from 900kg to 1,3 tons for the gun incl. breech mechanism but excl. the carriage/gun support/mounting. The 1,3 tons was for a 50 cal. gun and the 900 kg. for a 40 cal. gun. I have reserved 1,4 tons for armament which is broken down into 1,3 tons for the main gun, 50 kg for the HMG, 15 kg for the Co-ax, and 35 kg for crew pistols/SMGs, hand grenades etc. Gunsupports inside the tank would not be major problem, basically just two heavy plates in which the pivot can turn. Recoil cylinders and recuperators will need a redesign though (more compactness needed) but ought not to be a problem. In a 30+ ton hull you do not need as soft/long an recoild as in a field carriage. The British 3,7" for instance recoiled 32" in the field mounting, but only 18" in the fixed mounting. The 23,6" recoil set in the K40 with the 75mm/45 incl. a muzzle brake ought to be enough to have the tank "settle down" quickly after each shot.

AFAIK the turret of the T35/85 was redesigned because the turret ring was too small in the original turret. The problem IMHO was solved in a very smart way by pushing the gun pivot forward in an extension ahead of the turret ring. In the K40 design there should be enough turret ring "excess" to eventually mount at least a 90mm HV gun, but I would seriously considder a 75mm cal 60+ as ammo will take up less internal space (more rounds).

Regards

Steffen Redbeard

[Redbeard]

Originally Posted by Riain

It seems too big for a prewar tank design. The design parameters for prewar tanks were set by the size of train flatbed cars and tunnel dimensions, as well as the wieght that army engineer bridges could bear, which was about 20tons in the late 30s. German railways were a bit wider than British railways, so German prewar tank designs are a bit bigger than Brit designs. Russian railways are wider again so the T34 starts with that as a design parameter advantage. Designs started during the war traded the strategic advantage of easy rail transport for the tactical advantage of lots of armour and big gun. But within these prewar parameters there is a lot of scope for improvement, getting to 1941-2 standards from the start with good design forsight.

The K40 actually is 4 cm narrower than the Cromwell (specs. set in 1940). The extra turret ring on the K40 is achieved by having the upper hull go out over the tracks and having a torsion bar suspension instead of the Christie (as in Cromwell). The Churchill is 24cm wider than the K40 and specs. were set in 1939 and prototypes ready in 1940.

The PzIII and PzIV are 8cm more narrow than the K40, but the Panther is 30cm wider and the Tiger I is 73cm wider. AFAIK only the Tiger needed special tracks to be transported by the German railway system operating on a standard European gauge. The Tiger indeed needed some extra work to be transportable, but considdering how superior a weapon it was I think it was worth it.

Regards

Steffen Redbeard

[Redbeard]

Originally Posted by Hendryk

Great drawing. What is the width of the caterpillars?

50 cm - i.e. on par with T34.

Regards

Steffen Redbeard

[The Dean]

If the Soviet engine was not available would the K40 be able to use a Gardener or Cummins diesel power unit?

[Redbeard]

Originally Posted by The Dean

If the Soviet engine was not available would the K40 be able to use a Gardener or Cummins diesel power unit?

I don't know enough about the state of Cummins or Gardener diesels of 1940 to tell, but I guess there must have been a reason for the Anglo-Saxons to stick to petrol engines for so long.

I've been told that even in petrol engined tanks the fuel rarely caught fire, so the extra safety factor in diesels is hardly significant, but I like the extra endurance and torque. A petrol engine would not be a disaster for the concept though and would provide some logistic advantages, as a 1940's army hardly could depend on diesels alone. A 600 hp Meteor like in the Cromwell would make it a race car.

Concerning fire hazards ammo apparently was/is the great culprit, especially that stored high in the vehicle (like in M4 side pannels). That was a main reason for deleting the crew position next to the driver (hull Mgunner/radio operator) as that would give safe storage for 48 extra rounds easy accessible for the loader.

Regards

Steffen Redbeard