So I noticed in a lot of pictures that AFV hull sides are more or less completely covered by its tracks. It got me wondering about hull side protection.

Since the tracks would take up width, there should be less width available for armour. If there is less width for armour, there would be less protection against projectiles.

HEAT rounds would likely be set of prematurely by tracks, but kinetic penetrators would be relatively unaffected.

I am not sure of the effectiveness of side skirts.

I'd like to ask if anyone here knows RHAe values for hull sides of any AFVs but preferably MBTs and IFVs.

If anyone has access to armour schemes of any AFVs please post here too

Thanks in advance

In general you cannot protect side armour against a tank main gun. The area is too large and it's inopportunely placed (little or no sloping, etc.). It also won't be thick enough that width limitation is a big problem.

On that note I wonder if you could put up ERA plates on the skirts.

Nope. Nowhere to mount them.

I thought the skirts were rigid enough.
I don't mean the part over the wheels thou but the one over the top of the tracks that connects to the armor on the top of the body. In essence, you mount it at an angle near the top of the tracks where the skirts connect. But than again, that would not be that useful so forget it.

Red is armour

So maybe a block of armour protruding between the upper bound of the track and the top of the lower wheels

So at least the top half of the hull side gets armour and opposing infantry dont get cheap kills by firing RPGs into the side and blowing through the track/wheels + 10mm or so of chassis

TUSK disagrees

If that's meant to be solid block of armour then it's far too thick. Also there are running wheels in the way. If it's meant to be a skirt, then why not use conventional arrangement for that?

Realistically you can't protect against a tank round entering the lower side hull. The usual approach is to maximise front armour and try to always face the enemy, which actually works very well in practice.

How effective are skirts, really

I doubt the ability of skirts to withstand man portable HEAT systems in tight quarters like city or jungle fighting

You can protect the side hull from other tanks... just not when they're firing directly from the side. It's mainly intended to stop hits within the frontal arc but which do not hit the actual front armor. Now, how wide that "frontal arc" is varies depending on the tank in question. If you have very heavy side armor with very heavy skirts with ERA on top of that... well, the frontal arc would be wider than what you would see with most IRL tanks at the cost of being a lot heavier than most IRL tanks.

That depends entirely on the skirts in question. Are we talking relatively thin armor steel or are we talking about heavy skirts+ERA on top of that?

Abrams supposedly has 150-300mm of protection, including skirts and space, along the hull side.

In theory.