OOB 024 -- US Army -- M1A2 Abrams

[AMX]

Rubbish.
1) Autofrettage was developed in the 1920ies; while it's possible that Rheinmetall holds the patent for the best currently available method, assuming that others can't use it at all is nonsense.
2) All the more so as GDLS would likely have licensed said method along with the gun.
3) The weights in the article are off - their "best case" weight (2.7 tons) is far higher than the actual weight (1315 kg tube only; even with breechblock it's less than 2 tons).

[mr_clark]

You've got sources? I am really interested in the topic, but I havenm't found anything good.

EDIT: And personally I think the stabilizer in the Leo vid holds out better then the one in the Abrams ones, but that is all a question of terrain etc, so nothing to draw conclusions from.

[AMX]

1) http://www.navweaps.com/Weapons/Gun_Data.htm :

Autofrettage - A process in which a favorable distribution of initial or residual stress in a tube is induced, as in the manufacturing of gun barrels. [...] During the 1920s and 1930s, the US Navy termed this process "manufacture by radial expansion."

2) common sense
3) Paul-Werner Krapke: Leopard 2, sein Werden und seine Leistung; Mittler-Verlag 1986, page 98

Also note that the video shows a Leo2A6, which uses the longer (and heavier) 120mm L55.


edit: rheinmetall-detec gives the barrel weight as only 1190kg.
'Course, that mainly means the article's figures are even further from the truth.

[Marcello]

Speaking of Abrams, why does it have one of the highest top armor values in the game, even higher than tanks for which top protection was an important consideration like the Strv 122 or the Merkava IV ? As far as I know the top turret armor is around 40mm RHA, while the top glacis is around 60-80mm. Yet for example unit 24 (M1A2), OOB 12, has 10 and 20 as top armor, while the Strv 122 (unit 31 OOB 66) has 8 and 16. Was it due to game mechanics?

[mr_clark]

Thanks for the infos AMX, but I contest your second point of reasoning.

Why should Rheinmetall sell it's production rights to anyone just becasue they want to have the gun?
Especially if one takes into account that the DoD is normally not very generous in it's proposals to foreign contractors...

[pdoktar]

I think the game has US bias..
Well, maybe the oob designer gave himself some slack and figured out a KE number and doubleb it for HEAT. I think that the top-armor question and TA-warheads should be looked at in the possible next release of WinSPMBT.

[PlasmaKrab]

Just FYI everyone, I noticed that TA missiles using EFP warheads could be modeled using AP penetration instead of HEAT.
Here is a report hinting that armor effects of EFPs are closer from HVAP than HEAT (page 11, "The penetration process for EFPs is characteristic of high velocity low L/D kinetic energy penetrators")
In game, AP missiles just keep their whole penetration all along like HEAT ones, deal with KE armor values and are less sensitive to ERA, just like they should be.

Re. tank top armor, has anyone any hard data regarding design of turret roofs? I mean, prior to the Strv-122 and Merkava-3, was there anything else to it than thick steel plate, even in tanks of the Leo2/M1A2 generation?
Except for the still rare heavy add-on armor discussed above, I don't see what should give such a large HEAT standoff. And don't tell me that's the spall liner

[Jan]

as far as i know, top turret armor are usually not more than 15-25cm thick.

About Strv-122, it have more protection on some part of the turret (crew hatch and around crew position, no protection over rear turret). I've no figures for teh Merkava.

I think that such top turret add a bit crew survivability versus aerial bomblet, mortar, etc. but not verus top attack atk missiles.

Some tests have demonstrated that last ATK missiles like russian Kornet are actually overkilling existing tanks since RPG29 are sufficent to pierce actual tanks in their most protected part. RPG are also lighter and more widespread.

cheers,

Jan

[Marek_Tucan]

Jan said:
as far as i know, top turret armor are usually not more than 15-25cm thick.

Shouldn't that be milimeters?

AFAIK M1 Abrams in all incarnations is 5cm HHS RHA, T-72 has some 5,5cm (cast), Leo2 I have with 6cm thick roof in my tables... Older generation tanks have generally some 20-30mm, wwII and post-WWII ones even as little as 10mm in some cases.

Plasmakrab's idea to use AP for EFP projectiles is good IMO. Pity I didn't get it myself whiloe dealing with MRM KE/CE for my US OOB yesterday...

[Marcello]

"Some tests have demonstrated that last ATK missiles like russian Kornet are actually overkilling existing tanks since RPG29 are sufficent to pierce actual tanks in their most protected part."

I have my doubts that the RPG-29 can take pierce the front turret of the latest western MBTs. Hull front may be possible (IIRC some time ago a Challenger in Iraq was knocked out by a RPG-29 penetrating the lower hull front), but not turret. Weren't those tests performed on T-80Us and such anyway?
Besides RPGs are relatively short range weapons and the RPG-29/27 and high end RPG-7 rounds are neither that widespread nor cheap.

"I mean, prior to the Strv-122 and Merkava-3, was there anything else to it than thick steel plate, even in tanks of the Leo2/M1A2 generation?"

To counter what threat? The soviets were not awash in top attack weapons AFAIK. They had something but it was not anything worth sacrificing much weight over.

"I think that such top turret add a bit crew survivability versus aerial bomblet, mortar, etc. but not verus top attack atk missiles"

Preventing your tank from being destroyed by a couple of HEAT bomblets with a penetration of maybe 10 cm each seems a good investment today.