Interlinked

Thanks for sharing more fascinating knowledge, Doug. For the MBTs, is it true that short tracking wasn't possible because of the boat-like bulging hull shape? Did it materially affect tank recovery efforts that you know of?

Yes, but if the tank hits a mine, it's more likely for the front to have driven over the mine and therefore the front wheels to be lost and potentially face idler damage. Short tracking the tank would most often mean looping the track over the remaining back wheels. So rear drive sprocket is not only compatible with short tracking but also preferable, disregarding other factors that might come up when hitting a landmine, like a front transmission springing a leak from a blast or something.

It's the other way round, surely. The expectation is for the front roadwheels to be blown by a mine, and short-tracking a rear drive tank would mean both tracks are powered. Front drive would mean one side is unpowered, thus you need to constantly make adjustments as the tank will tend to veer towards the unpowered side on most surfaces.

Oh, I misremembered, I thought the first generation of those cored APFSDS rounds like the one fired from the T-12 and the T-62 had no cap, but they do.

Here's an interesting thought - postwar Soviet APFSDS put tungsten carbide cores in the nose behind either no cap or a marginal cap. These had muzzle velocities of 1,600-1,800 m/s. The core of the 125mm BM15 round was essentially the same as the core out of a 45mm APCR round. Perhaps not identical but essentially the same. The cores in those rounds do not (?) shatter even at those incredible velocities.

TQ

What is the composition of the target plate in the test?

The idea of a 37mm gun as fighter armament came shortly after Barbarossa, long before the problem of defending against heavy bombers became a real concern. There was a mid-war desire to give fighters "universal" gun armament, and when this was combined with a preference for a 3-gun combo of 2x lighter guns + 1 heavy gun, fighter gun armaments built up a final configuration of 2x 23mm + 37mm. The 37mm was developed during the mid-war period because it could give the desired "one hit kill" capability against tactical aircraft (not bombers) while also having good effects on ground targets. It was not conceived as an anti-bomber weapon. Earlier configurations included 2x 12.7mm + engine 23mm, then 2x 20mm + engine 23mm, and then 2x 20mm + engine 37mm. During the creation of the Yak-9UT, it was recognized that 2x20mm + engine 23mm was better for air combat, while 2x20mm + engine 37mm was more flexible because of better effects on ground targets. This evolved into 2x 23mm + 37mm in postwar fighters and was carried over to jets.

Well, M85 certainly cannot be ignored as the "3rd generation" heavy machine gun of the U.S. Whether the M2HB should be considered "1st" or "2nd" generation is not so clear to me, because mechanically the M2HB was just an M2 re-tuned for a heavy barrel, and mechanically the M2 was just an re-sized M1917. The DShK coming in much later does not really justify labeling it a 2nd generation gun, it just came late. From a technological point of view these guns are basically at the same level and conceptually they are the same. When we get to the M85 and NSV though, we see a new concept. Firing controls were no longer built into the gun. Instead, the guns were a module in a system, which included a sight module and trigger module separate from the gun. The M85 was meant for a rigid mount and recoil impulse was smoothened by the short recoil action, while the NSV was meant to reciprocate in a shock absorbing mount. We also see a systematic design effort on shortening the receiver by minimizing bolt length by choosing new locking methods and by using new feed systems that took up receiver width rather than receiver length. But energy management in the NSV was leagues ahead. The NSV had more reciprocating momentum because it had a bolt carrier, while the M85 had just the bolt. The NSV bolt carrier had 2 rollers supporting its weight on the receiver guide rails, plus 1 lateral roller on the right to control lateral alignment. The entire bottom face of the bolt carrier was shaped into a long track in which the roller of the feed rocker arm rode (also controlling lateral bolt carrier alignment). The rocker arm rotates a shaft which goes to the top of the receiver, where there is another rocker arm mating to the articulating linkages in the top cover, and those linkages move the feed pawl side to side. Thus the NSV gets high belt pull force over a long pull time, with minimal energy lost to sliding friction in both recoil and counterrecoil. Plus, like the DShK, the NSV had de-linkers. The pointy ends of the de-linkers (the shiny pointy bits on the feed tray in the image below) go into the gaps between the belt link and the cartridge, and as the belt got pulled in, the cartridge gets pried off the belt by the curved shape of the de-linkers. The de-linked cartridge is positioned to be fed into the chamber with hardly any energy at all from the returning bolt. So in a first-shot condition (bolt held by sear, return spring at cocked position is the only source of energy), a dirty gun with dirty belts should feed and fire fine even when pointing straight up to shoot at aircraft or something, because the hard parts of feeding were already done by the previous cycle. The M85 energized its feed mechanism from the short recoil stroke of its barrel extension. The barrel extension pushed on the short end of a feed actuator lever, and the long end of that lever had a slot in it, fitting a lug from the end of a feed lever in the top cover, and the other end of that feed lever moved the feed pawl side to side. The short recoil supplies plenty of belt pull force but over a short time, so the belt is jerked roughly. That is almost certainly the cause of its sensitivity to the belt alignment and feed angle, but I can't speak on any of its other issues. The lack of a de-linker and subsequently higher sensitivity to belt cleanliness and gun elevation angle explains why the M85 was less reliable in the low ROF mode. The low ROF mode was achieved by blocking the bolt assembly from reaching the buffer spring during recoil, so excess recoil energy was lost rather than returned for counterrecoil. Every cycle in the low ROF mode was therefore functionally the same as a first-shot condition. Economically I strongly doubt NSV made any sense. New 12.7mm machine guns simply weren't needed in big numbers. During WW2 there was an urgent need for more DShKs since single DShKs on a tripod formed the backbone of infantry air defence, and the next lower air defence weapon below 37mm guns. By the 1960s, 12.7mm machine guns were no longer seen as an infantry weapon except in rare cases for airborne infantry and potentially mountain infantry. It was also needed only in small numbers as fortress guns. By far its biggest role was as an AA MG on tanks and occassionally self-propelled artillery. Lighter AFVs had either a 7.62mm, or a 7.62mm + 14.5mm. For export and licensing, NSV production was tied to tank production license in WP, similar to how the M2HB spread in W. Europe because it came packaged with tanks.

Hello Bojan, can you share it again? I don't know the interview you're referring to.

Perhaps the most apparent benefit of a deep wading capability seen in day-to-day use is that tanks built to do deep wading would tend to be more tightly sealed than those which aren't, especially in terms of the engine compartment design and in the turret ring. The placement of the engine and radiator exhausts and the intake plays a critical role here, and deep wading capability has an impact on the engine compartment design approach taken early on.

Reactive armour as a rule is made from a sandwich of explosives between metal plates. When it detonates, it throws the front and back plates apart. A heavy reactive armour might have the back plate fixed to throw only the front plate, and this front plate is made extra thick and heavy to damage the penetrator. So you can have ERA that's thin and mounted at a small distance away from the armour like Blazer and potentially what you see here on the CR3's sides, giving the appearance of thin armour. However reactive armour needs to be angled to work effectively, so when installed on the flat sides of the turret, it will work against a shot coming from the front at an angle but not a shot coming directly perpendicular to the turret side. Meanwhile, the thick blocks you see on "Megatron" almost certainly contain thin sandwiches arranged like window slats to handle hits perpendicular to the flat sides of the tank. That's how ROMOR-A looks inside. Although such add-on blocks appear thick, in reality a passing shaped charge jet may intersect only one sandwich, or intersect the bottom edge of one sandwich and the top edge of another sandwich. Because you're not relying on being shot from a favourably angle, this arrangement adds more weight.

In battle drills he's supposed to go out the hatch, but on paper it's possible to go out the back? It's not faster than going up through the hatch but possible.

Kontakt-5 throws its heavy flyer plate outwards at a reference velocity of 200-250 m/s (depending on source), but there is some unknown but significant variance between the glacis, hull side, and turret panels.

T-90M puts anti-slip on its ERA too, btw.