Yoshi_E

On 1/10/2024 at 3:05 AM, jojoisgood said:

So is this illustration true or false ?

If dm63 have 730mm length of rod

and have 720mm at 2km it will need 1810m/s muzzle velocity, which will have 2km 1710m/s velocity .

The illustration shows RHAe - not RHA values. RHA being just a block of steel - while RHAe is often a simulated target of special armor.

Modern rounds are specifically designed to deal better with special armor - something that you cant just calculate.
As @FORMATOSE pointed out, I dont know if those are the official KMW/RH figures - or their own speculation.

Thanks to more recent pics we know the penetrator is a bit longer than we initially assumed:

Here is a better example that talks specifically about a steel target:

Quote

With the currently most modern 120-mm APFSDS (DM63, effective length 745mm), penetration rates of 650-750mm are achieved in a steel target (tensile strength 800 MPa / 237 HB) - depending on the impact velocity (1500-1600 m/s at a distance of 3000 m) and the impact angle (0°-60° to the surface normal)

650mm@0° at 3km
750mm@60° at 3km

On an old Bundeswehr slide from 2004 or so they lists DM53 as

Quote

reaches up to 1800 m/s and can perforate on a distance of 2000 meters up to 810mm tank steel

If you now also take into account that DM53/63 can bypass ERA such as K5 (~250mm RHAe) by non-initiation - you will arrive at the requirement of LKE II to perforate 1000mm RHAe

On the topic of armor, there was this nice slide of the Perun Army in 2021 that was discussing the acquisition of older Leopard 2A4 tanks with apparently upgraded internal armor.



550-600mm arc protection on Leopard 2A4 - possible the drop-ins that were mentioned?
The Mantlet would seemingly receive no improvement and stay at ~315mm RHAe.

On 12/27/2023 at 1:24 PM, SH_MM said:

The hinge-mounted armor module next to the gun mantlet consists just of four steel plates and weld lines, just as described by

Im not yet fully convinced that the lines are just simple weld lines. Thats why I initially brought this up.
In the center the blocks are directly welded with a smooth finish.

On the outside they are cut into the steel and then filled - non of the lines have any visible typical weld patterns (though could be covered by thick layer of paint). Butt joints like these also usually bulge out of the plate - instead being embedded. Why is the pattern irregular (but also identical on all tanks)?

If they are strongly welded together, why would there be two additional bolts to strap all the four blocks together?

That's why I wondered if these might be crumple zones to allow for some minimal shift of the blocks to feed more material against a penetrator. I wonder if that could work for thicker blocks like these, maybe someone could simulate it.

Anyway lets leave it at this, discussing it further would be unnecessary.

The blocks are around 360-370mm thick based on my current estimate. Each section including the joint lines is 100mm, with the last block being a bit thinner, around ~60-70mm.

Gunner side is 542kg - Loaders side is 389kg (@ TWMSR)

 What makes you think that the gunshield is some aluminum alloy? Its definitely some sort of tempered metal.

Here a short animation displaying the parts

The model is based on a mix of 3D photogrammetry scans of the entire turret and schematics, but still needs some fine tuning.
 

On 1/15/2023 at 1:21 PM, TWMSR said:

Right one is 542 kg, left one 389 kg. If you model it you can check density.

For the right one I currently got 0.0707m^3 * 7750kg/m^3 ~= 548kg but the model is not fully tweaked yet.

Im assuming thats without the bolts and the part attached on the back?

Thanks for the info.

Do you, or anyone else, have an idea why there is a 2nd hole below the MG that goes all the way through, even through the armor plate of the mantlet?

On the Inside it looks like this:

I assumed it would be just the mount for the MG and or a reservoir for the recuperators/intensifiers of the recoil system, but that doesn't seem to be the case?

Why does it go all the way through, not only the cradle, also through the mantlet armor plate, but not the Mantlet main armor blocks.

Or is it just and access for maintenance hatch will be closed before the gun mantlet armor is installed?

Just like the MG Its not present in any form on the new 130mm.

Edit: Seems to be a manual smoke extractor as far as i could find. 

3 hours ago, Pardus said:

What makes you say that? We're talking 4 hollow steel boxes (or modules if you like) with angled NERA plating inside as its the best protection vs weight option for that area. 

Thats incorrect, the blocks themselves are much simpler in nature. They are solid steel blocks as I described them previously.

What im interested is this part:

The part that is secured by the bolts and has been removed here:

This armor block is a one piece block with cutouts for a polymer at a 90% steel 10% polymer ratio, making 4 steel and 3 polymer layers.

However I find the use of the screws in this construction rather odd.

These bolts pass through the block and connect to something on its back. There is no threading on these bolts that interact with the steel block. They just pass through.

Does anyone know how the backside of this armor block looks like / whats attached to these bolts?

Presumably these screws ontop attach to the same thing.

You can even see a glimpse of it next to the gunner optics:

On 5/26/2020 at 10:05 AM, Scav said:

I suggest using the factory brochure since it's from 1982 and that's going to be more accurate than those webpages.

The current version is going to weigh more as a result of a heavier barrel, none of those seem to have this, so they are most likely wrong.

You think the value Rheinmetall has given is wrong? I doubt that. It also matches the recently measured weight on Pz 87.
The barrel weight is commonly given, and known for all L44 and L55 variants.
I think its more likely that the system or the armor on the system was changed, or increased in weight since 1982.
E.g. the Turnunion there was not manufactured that precise in 1980, it should also be slightly smaller due to additional paint layer. Other changes could be the recoil system. The mount system for the MG was also changed.

So 3655kg for Leopard A0-A3 and 3780kg or 3800kg for Leopard 2A4 - Leopard 2A5.

17 hours ago, Scav said:

Where do you get 3780 from?

I summarized all weights here:
http://gamesound.eu/res/leopard2/leopard_120mm_compare.svg
In most sources 3800kg or 3780kg is given (especially for more current version)

@SH_MM Source to that? It looks alot like the 2AV armor array, how much is that applicable to Leopard 2A4, considering that the armor layout between them were changed quite considerably?

On 5/21/2020 at 9:51 AM, Pardus said:

420mm NERA + 240mm RHA should make for some pretty impressive protection. Using a 0.5 RHAe modifier for Tech B armour you get 210mm RHAe + 240mm RHA backing, so that's a 450mm RHAe mantlet.

Seems about right

On 5/17/2020 at 7:53 PM, Scav said:

Why all this guessing?
https://drive.google.com/file/d/0B4xitrrBUDsYckRhSXNNSXpKbkE/view?pli=1
Gun cradle weight of 595kg, and all the other stuff you can probably use translate for (this is most likely for Strv 122 as well, not Strv 121).
So gun cradle on 122 is steel, not titanium, weight in this location doesn't matter as much as it's right on the pivot point, inertia and balance doesn't change a whole lot because of it.
 

I had that file already in my folder... guess i overlooked it or got deterred by the language. Thats why this thread is a gold mine
The swedish document was difficult to translate, but I manged to find everything other than "Framförare vikt : 36kg" Translation is something like: "Front - Recoil reducing". Im assuming its part of the hydraulics / recuperators, but the "Front" part in it doesnt match that.

I updated my post, though the total mass is still off by some 540kg. Other than the cradle tube i cant think of other locations where this weight could be. Any ideas?

@Pardus:
240mm thickness
728mm wide (Swedish documents list 910mm including the bearings)
500mm tall
The central hole should be around 310 mm in diameter (from the Swedish document)
The smaller ones are larger on the inside and smaller on the front, but in general it should be 30-80mm in diameter.

Based on:

I spend recently a bit of time with the Rh-120mm L44 gun.
Here are my findings (weight estimation):

Here are also some great pics of the L44 cut open: