Let me answer one by one by one
What is the primary difference between nera and era other than one explodes and other doesn't?Which is more effective?
NERA or NxRA are basically the same stuff as in ERA. The only different is the Armour does not line with Explosive liner.
ERA work by "Pre-explosion" to deflect the damage of incoming around. While NERA or NxRA have the inert liner (mainly rubber) rubbed in between two Metal layer, and when the round hit metal, the metal displace the incoming projectile because of the inert layer (Well, because rubber moves around) and hence even a tandem charge will hit a different part of the metal plate, hence defeating the tandem warhead.
ERA is more all rounder than NERA, while NERA is better deal with Tandem charge warhead.
Also, NERA/NxRA have an advantage over ERA when you talking about transit, logistic and replacement, as there are no explosive substance inside.
What is more effective composite armour modular package or ERA/NERA?
ERA - ALL AP/AT Round except tandem round
NERA - ONLY AGAINST Tandem Round
Note that ERA is a 1 off armour with heavier substance, when the explosive layer detonated, you are required to replace it. While NERA/NxRA round is lighter and non-expansive armour block. It can be reused
Why is skat armour only used at the back of the tanks and not all around?
Do you mean "Slat" armour??
Honestly, I don't know. The reason why they put it on the back is because they are light weight and good for RPG defence. That's it. Most likely a sitrep issue when you put it 360, it may impede your turret mobility. That would be my guess.
How useful is HESH round?
HESH work by seismic vibration(Or Seismic wave), it work best on sealed/concealed target (Ie cabin of a tank or building) Absolutely useless for anything else.
Is it possible for carousel type autoloader to use long rod penetrator effectively due to limited size of autoloader?I heard that this is major disadvantage of carousel autoloader that it can't match length of western size long rod APFSDS rounds as autoloader can't hold it and so penetration capability is lesser.
Thanks.
Carousel autoloader inside a tank is limited by the round size. As the bigger/longer the round is, the larger carousel is needed. The disadvantage you are talking about exist as all carousel loader work in a 2-pieces fashion. (Basically break down a round into projectile and charge) to lower the diameter you need for the carousel.
But most of all the autoloader is hampered by one major issue other than the carousel itself, but the safety of the round. As there are no way a gunner can jam the gun on a single piece manual loader (Actually, it can, I saw once by the fine work of a US Army Gunner.......). But this can happen when you are using an autoloader. Hence the charge used in the autoloader system tend to be less powerful than a single piece round, thus preventing excessive gas and explosive residue and back fire the gun.
