Why was the ammunition hatch welded shut in the Leopard 2A3?

[aurens]

One of the distinguishing features of the Leopard 2A3 from it's predecessors was the fact that the ammunition loading hatch in the left side of the turret was deleted and welded over.

 

 

 

Above is the old ammunition hatch on a 2AV and a crewman passing Sabot to the loader through the hatch. Below is the remains of the hatch welded shut on a Dutch 2A6.

 

 

Does anybody know why it was welded shut? My best guess is that it promotes damaging of the fragile casing, thus creating a fire hazard. Has anybody seen 120mm ammo damaged during loading that spilled propellant?

Edited April 4, 2018 by Nate Lawrence

[Gibsonm]

These hatches were initially designed for the removal of spent shell casings (not necessarily for loading fresh ammunition).

 

The 105mm L7 has a sizeable shell case that need to be removed after a few rounds are fired to "de-clutter" the fighting compartment.

 

For example:

 

 

120mm ammunition with the base plug instead of a shell case meant you could fire fare more rounds before you had to "de-clutter".

 

For example:

 

 

I'm not sure but perhaps the initial 120mm rounds still had the large shell case? I suspect that after the introduction of the combustible shell case, the hatch was deemed superfluous and removed.

 

Edited April 4, 2018 by Gibsonm

[aurens]

14 minutes ago, Gibsonm said:

I'm not sure but perhaps the initial 120mm rounds still had the large shell case? I suspect that after the introduction of the combustible shell case, the hatch was deemed superfluous and removed.

 

As far as I know, the Rheinmetall 120mm L/44 was used from the start with combustible cases. I could be wrong, but it doesn't make much sense to use full metal casings as standard ammunition on a gun designed for combustible cases.

[Ssnake]

It simply was determined to be a non-negligible weakness in the ballistic protection, and not really necessary anyway (because you can throw out the case stubs through the loader's hatch, unless you're under NBC conditions, in which case you couldn't have used that flap either).

[Marko]

Talking to some of my older army buddies.

The rank and file guys preferred the old one piece shells 

As they made quite a bit on the side from the spent brass casing from some of the older generation arty shells. 

Edited April 4, 2018 by Marko

[aurens]

12 hours ago, Ssnake said:

It simply was determined to be a non-negligible weakness in the ballistic protection, and not really necessary anyway (because you can throw out the case stubs through the loader's hatch, unless you're under NBC conditions, in which case you couldn't have used that flap either).

Reminds me of the Panzer IV's turret side hatches compromising the ballistic integrity of the turret, it's surprising how that small ammunition hatch constitutes a threat to the turret ballistic protection.

[Ssnake]

Well, the most basic thing is that where the hatch meets the surrounding turret, that crevice itself is a weak area. Then there's what's called the "edge effect" which creates a weak zone up to two calibers in diameter as the impact point approaches the edge of a plate. In this case, if we're talking about a 25mm diameter APFSDS rod and a 14 x 14cm square flap, that's a total area of  4 x 14cm x 2 x 2.5cm x 2 = 560 cm² where the ballistic protection drops below the required strength even if the hatch was of exactly the same strength and composition as the surrounding turret wall.

Furthermore, an attack from a frontal direction into the turret flank that perforates would then likely also perforate the ammo shield door and then probably ignite the propellant of the ammo stored in the ready compartment. So, it's really an unnecessary risk, given that there's actually no strong argument to be made as far as functional requirements are concerned.

[aurens]

On 4/4/2018 at 3:55 PM, Ssnake said:

Well, the most basic thing is that where the hatch meets the surrounding turret, that crevice itself is a weak area. Then there's what's called the "edge effect" which creates a weak zone up to two calibers in diameter as the impact point approaches the edge of a plate. In this case, if we're talking about a 25mm diameter APFSDS rod and a 14 x 14cm square flap, that's a total area of  4 x 14cm x 2 x 2.5cm x 2 = 560 cm² where the ballistic protection drops below the required strength even if the hatch was of exactly the same strength and composition as the surrounding turret wall.

Furthermore, an attack from a frontal direction into the turret flank that perforates would then likely also perforate the ammo shield door and then probably ignite the propellant of the ammo stored in the ready compartment. So, it's really an unnecessary risk, given that there's actually no strong argument to be made as far as functional requirements are concerned.

Where did you learn so much about terminal ballistics?

[Ssnake]

A lot of what I wrote is also described in "Armor Basics.pdf", which is part of the Steel Beasts documentation (...that is, in the "Documents" folder).