Monday 7 May 2018

The Future of Tanks

"Theses of the report by the commander of the Armoured and Mechanized Forces in the Group of Soviet Forces in Germany, Marshal of the Armoured Forces Rotmistrov, titled "Tanks of the Soviet and Foreign Armies Presently, and the Potential of Their Development"
March 24th, 1947

Overall conclusions regarding the tanks of WWII and the potential of its development:
  1. Due to the thickening of armour and gun calibers, light tanks are departing from the battlefield. The amount of medium and heavy tanks is increasing.
  2. The protection armour offers is, chiefly, increased by increasing its thickness. 200 mm thick armour will be very common soon. Ground pressure and acceptable width for railroad transport will be the limiting factors in increasing the thickness of the armour any further. In the future, it will be important to change the quality of the armour. Simply increasing the thickness of the armour is a dead end. The protection must be increased not by adding more armour, but by improving its qualities and using composite armour.
  3. The effectiveness of tank guns grows linearly with the increase of the caliber and barrel length. Guns are designed to fire directly at long ranges (1-2.5 km), which dictates their caliber and muzzle velocity, which also raises the requirements for observation devices.
    The penetration of guns increases, mostly, by increasing the muzzle velocity and the gun caliber, and the muzzle velocity is increased by lengthening the barrel. It is obvious that increasing muzzle velocity by lengthening the barrel any further is unrealistic. It is possible to improve in this category by creating improved explosive substances and the qualities of the shell itself (mechanical qualities) and the design of the gun barrel.
    For example, guns with conical 28.20, 42/28, and 75/55 mm barrels appeared, which increased the speed of a subcaliber round to 1200-1400 m/s.
    To illustrate the impact of a high muzzle velocity and mechanical toughness of the shell on its penetration, it is sufficient to demonstrate this example. Shells for the 90 mm gun of the American T26E4 tank equipped with a tungsten carbide core are capable of penetrating 355 mm of armour from 275 meters.
    The caliber is also approaching its limit, as increasing the caliber rapidly increases the weight and size of a shell, which means that loading becomes more difficult and less ammunition can be carried.
  4. The engine group is not mature in the sense of the range of power outputs an reliability. The power output range is a weak point, which slows down the modern development of tanks.
  5. Observation devices, turret traverse mechanisms, and gun stabilizers demand more attention than they are currently given. Precision and agility of tanks depend primarily on the maturity of these components. 
Maximum weight of a heavy tank

Since the main tanks on the battlefield are tanks with powerful armour and armament, it is important to determine the limits of thickening the armour of such a tank. If we postulate that the tank must not be taken apart into pieces and must be transported via railroad without any complications, then the limits of the tank's weight are defined by the acceptable width for railroad transport, ground pressure, and the ratio of the length of the contact surface to its width, which dictates the agility of the tank.

If we assume that long range transport will be achieved by special towed platforms, then the width restriction can be increased, thus increasing the maximum weight of a tank. The thicker the armour, the smaller the dimensions of the engine-transmission group must be. Ultimately, they determine the maximum thickness of the tank's armour. The thicker the armour, the smaller the useful volume inside the tank, and less space is left for the engine and transmission. For a tank with powerful armour, a T-34-like shape is inevitable. 

Assuming the maximum acceptable width is 4 meters (such a tank will be transported by towed platforms), the weight of the tank can be increased to 100 tons, and the thickness of the armour to 350-450 mm.

If we build super-powerful tanks with the restriction of the railroad width, then the maximum weight of a tank can be 97 tons.

Given the present methods of tank layouts, the thickness of a tank's armour cannot be more than 350-450 mm if it is to be transported by railroads. It is obvious that even with modern tank guns (100-128 mm in caliber) further increase in muzzle velocity can achieve penetration, if not of the plates themselves, then their joints, from 1.5-2 km. After that, a leap must occur in the quality of armour and guns. It will soon be impossible to simply grow the length of a barrel or the thickness of armour. Quantity must be turned into quality. In the meantime, 300-350 mm thick armour will allow the creation of a first class breakthrough tank in modern conditions."


  1. What do they mean by "composite armour" in this period ? face hardened ? Very hard plates laid over softer plates, Space armour ? I have no idea, thanks for any answers.

    1. Face hardened armour was old news by 1947, spaced armour was explored thoroughly in the early 40s. This is "true" composite armour they're starting to think about, in the modern sense.

    2. The British "plastic armour" (actually more like asphalt) could probably be seen as an early practical application of the general concept:

      Or perhaps more accurately modern revival, given the great antiquity of the principle in personal defenses (scales attached onto textile or leather backing being the oldest form of metal body armour) and more recently in the "compound armour" of 1800s warships (thick inner layer of teak as shock absorber and "spall liner")...

    3. The British were considering using plastic armour for protection from small caliber weapons and bomb splinters as well. I have a document with the calculations, pound for pound it isn't as good as armour, but much better than mild steel.

    4. If memory serves by the Korean War the Americans were experimenting with adding a layer of enamel onto the front face of body-armour plates as an early form of ablative defense (fabric coating was soon added to catch the debris knocked off), so there was that line of research too. Probably not very relevant for AFVs though but illustrative of the thinking in general moving on from plain steel plates.

    5. I know that Face hardened armour was invented in the 1890'ies and spaced armour in the 1940'ies (and even much earlier in ships). As for plastic armour: it was used as a steel substitute for providing splinter protection in places where weight didn't matter. (think AA gun tubs on merchant ships). The US tried a prototype with plastic armour added of the M4, but it added too much weight to the tank if they added enough to give any meaningful extra protecttion over the base armour scheme (don't have my books here so no exact numbers )

      So i wonder: if this 1947 document refers to composite armour are there any other documents, evedidence etc.... that "moderen" composite arour was already being considered in 1947.

      (Minor nit pick: compound armour was developed in the 1880'ies and consisted of a hard brittle steel plate welded onto a soft iron backing plate. wooden backing had other purposes, but discussing this would take us to far here)

    6. The germans developed and tested extensively SCHOTTPANZER, a combination of an array of ductile and hard plates laminated together, as early as 1942/43. It was considered for E100 at one point.
      Advances in HEAT technology convinced them 1944 that thick armor will be a dead end technology, intereting that the soviets took much longer to arrive at this point.

    7. By 1944 the Soviets were already producing variable thickness cast armour. I don't see how you can possibly claim that it took them "much longer" to arrive at the conclusion that simple thick armour is a dead end.

    8. IIRC the Brits were already riveting hard plates over soft ones in at least some of their pre/early-war Cruisers - mainly as a simple and cheap way to get the benefits of both types, but same general principle. (In the field of body armour this idea was already used in the Early Modern bulletproof cuirasses.)

    9. bolting two plates together doesn´t count, it´s a stop gap with negative figure of merit compared to a solid plate. Composite armor against full calibre AP is a pretty old (1870´s) thing in naval application (google COMPOUND ARMOUR and it´s derivates), which never prooved to be stronger than contemporary, homogenious nickel steel armor. During ww2 a very different set of requirements (HEAT and subcalibre APCR) drove the innovation of composite armor.

      And yes, Peter, if the soviets keep claiming during 1947 that 300-350mm armor would be a good future investment for a heavy breakthrough tank, than sincerly they failed to get the message. Evolution of HEAT makes any practicable amount of thick RHA armor superflous. and HEAT is much less affected by high obliquity than AP/APCR/APDS, providing that the fuze can be relied upon to function. That´s why the whole MAUS/ E100 program was cancelled in the first place during 1943 and 1944, respectively, with no follow up programs issued.

    10. I like how you missed the "In the meantime" - realistic planning must proceed from what is actually available, not something under R&D that will only yield operational designs God knows when.

      Also pretty sure the silly German superheavies were axed out of entirely valid economic and logistical considerations, not at the time still essentially theoretical concerns over what HEAT technology might mature into down the road. Period shaped-charge performance wasn't particularly awe-inspiring after all and only really took off well after the war.

    11. In opposiiton to what You claim, german ww2 HEAT research demonstrated that 6.6cm HEAT rifle grenades (6.6cm Schiessbecher Hl.Gr.43) with improved liner geometry could penetrate MAUS with up to 250mm RHA penetration.
      They fully understood what could be done with better liners, or for example, with deletion of spin (Hl m. Klappleitwerk/ Hl. m. Minenleitwerk). And it didn´t took much to get what can be done with 7.5cm - 8.8cm or larger HEAT warheads.

    12. Critical mass: do you have any sources on the reason for ending the Maus/E100 programme due to HEAT ?

    13. That's some wildly optimistic projections for a 66 mm rifled warhead... nevermind now that the major land-war headache, the USSR, wasn't really a major user of HEAT munitions anyway.
      Should THAT indeed have been a factor in canceling the superheavy programs as cm claims it'd then mean the Germans were being utter idiots spooked by hypothetical what-ifs.

      Conversely every single history of the designs I've ever read has been quite unanimous they were axed on entirely sensible industrial-logistical grounds as soon as Speer could talk that much sense into Der Führer, which sounds a few orders of magnitude more credible and less stupid.

    14. I'd also point out that this supposed worry over improving hollow-charge performance didn't particularly seem to stop the Germans from producing say Tiger IIs with rather noticeably less armour all around than the canceled superheavies... bit of a consistency issue with that claim, that.

    15. CM:

      "And yes, Peter, if the soviets keep claiming during 1947 that 300-350mm armor would be a good future investment for a heavy breakthrough tank than sincerly they failed to get the message."

      Uh, in what time frame does this 'message' arrive? The Soviet heavy line of IS and T-10 tanks where the bogeyman of NATO ground forces from the end of WWII until the 1960s, almost 20 years after this document appeared.

      As for HEAT rounds being the wonder weapon that defeats all armor problems of the postwar period, at least in the hand-held infantry form some of the applications left a lot to be desired. I recall in the Vietnam War a US infantryman firing his M72 LAW at a oncoming NVA T-34/85, a tank whose armor was verging on inadequate by WWII's end (especially the 45 mm hull, which was overmatched by just about every tank weapon it was likely to face). All the M72's warhead's impact did was to burn the paint a mite, and that was about all. This too was an event that happened 20 years after this document was penned.

    16. Not to mention that this document makes no claims that such an amount of armour "would be a good future investement", although the LoS thickness of 270+ mm in the T-10 was getting pretty close, but rather ballparks what *might* be required in the near future and the practical upper limits of what can be achieved within the contemporaneus technological and logistical limits.

      It's a theoretical overview, not a production plan. In practice the Soviets stuck rather firmly to their self-imposed ~50 ton upper limit - Hell, even the new T-14 Armata seems to be trying to respect it.

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