The Greater Luthorian Empire wrote:While the latter may be true the former hardly is. Hell one of the main reasons that Americans opposed the adoption of the 76 mm gun on Shermans in WW2 was due to the fact that it would decrease explosive payload. It isn't like tanks primarily fight tanks, most of their targets will be infantry, light vehicles, and buildings, and with modern FCS I doubt that the lower velocity of full bore HEAT is a crippling factor against vehicles.
The opposition was overstated. 76 mm armed Shermans performed fine in the role of supporting infantry. It was mostly a justification to keep the delineation between tanks and tank destroyers intact and support tank destroyer doctrine, which many officers had invested their careers in.
The difference in muzzle velocity between the M830 and sub-caliber M830A1 is significant: 950 m/s vs. 1,400 m/s, or nearly a 50% increase. Conversely, that results in time-of-flight decreases of roughly a third. That is not an insignificant gain at all. A target traveling at 40 km/h at a distance of 4 km can travel over ten meters in the one extra second the M830 will take to reach that range versus the M830A1, which is enough to miss even an MBT completely if improperly computed.
Meanwhile, there actually isn't any noticeable loss in lethal radius, strange as it may seem. This was already determined during WWII, and is one of the reasons why large-caliber artillery pieces in the 203 mm range have all but vanished. If the explosive relies mostly on fragmentation (and the most lethal shells do) over concussion, the speed of the fragments is determined by the shell's explosive velocity, which is determined by the explosive composition, not the explosive weight. The difference is in the number of fragments and the concussion effect, as a physically larger shell will have more fragments and thus a higher density of shrapnel within its lethal radius. The effects of weight reduction on shell lethality are relatively modest in a relative sense.
This isn't what most tanks end up facing though. The real threat isn't ten men in one foxhole, it's taking out specific positions because nowadays even insurgents know not to bunch up and become a target. Instead, the usual employment is against machine gun nests, where the difference between a five meter and an eight meter lethal radius would be moot so long as the shell is accurate enough to hit. Or an ATGM team hiding in a small trench. Johnny Taliban sitting in a little firing nest with his RPG-7 certainly doesn't care whether he's getting shot at with sub-caliber or full-bore HEAT rounds.
The Greater Luthorian Empire wrote:Well I think part of this conversation branched off from Galla's idea for only using two types of munitions, APFSDS and HEAT. If you were to only field two types of munitions like that the explosive payload of HEAT becomes much more important. Otherwise I honestly couldn't care less, APFSDS for tanks, HEAT for other vehicles, and HE for infantry and buildings. HEAT can work against infantry but if you field dedicated anti-infantry HE anyway it is more of a secondary role and is of less importance.
It's the US Army's idea. Using just two rounds vastly simplifies logistics, which is why the Army plans to replace everything that isn't APFSDS with XM1069 AMP, which also adds airbursting capability. And IIRC, a delayed fuze option for bunker and wall busting.
Posted: Wed Oct 29, 2014 10:09 am
