OOB 024 -- US Army -- M1A2 Abrams
 

The tank is accessible since 1993.
But the gun at it is established " 120mm M256 94 "! http://forum.shrapnelgames.com/images/smilies/smile.gif

Re: OOB 024 -- US Army -- M1A2 Abrams
 

I think that weapon n. 247, OOB 12 is supposed to represent the M829A2 round. Some sources mention 1993 as adoption date.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Things like that happen all the time. The '79 Patton has the same -80 gun as the 1980 M1...

Re: OOB 024 -- US Army -- M1A2 Abrams
 

And a year or 2 is entirely irrelevant - the "years" are simply markers (strings) to make it easier to figure out which of the 999 different NATO 105's or Soviet 100's in the OOB the darned thing is meant to be closest to.

Andy

Re: OOB 024 -- US Army -- M1A2 Abrams
 

I was wondering if the article I found can be true.
Unfortunately it's in German.
http://www.wfg-gk.de/warum36.html
But to bring it to a point; it says the Abrams can't fire while moving because the gun-tube is to heavy (50% heavier then the Rheinmetal L44 or L55) so the stabilizer (NATO standard) is to weak.
Does anyone knows more about that?

Re: OOB 024 -- US Army -- M1A2 Abrams
 

What is indeed interesting is that is a rather new article (January 2006) and supposedly from DMZ which is a quite renown military technical magazine in Germany, so i'd rather say the article has some merit.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

One, Two, Three, One!

Granted the Gun barrel isn't moving much in those vids.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Yeah, but they are all single shots at a very low speed in those vids... not what I would expect from a modern tank - full speed and several shots - and of course most of them on target...

Re: OOB 024 -- US Army -- M1A2 Abrams
 

For clarification I'll try a "on the run" translation of the main claims of the German article.
I made personal comments in brackets () to explain things that might get lost in translation otherwise.

"Um die erforderliche Anfangsgeschwindigkeit von 1.760 Metern pro Sekunde zu erhalten, muß ein Rohrinnendruck von über 7.000 Bar sicher beherrscht werden."

'To hold whilke firing a round with a starting speed in exces of 1760 meters a second the Barrel must manage to hold an interior pressure of up to 7000bars'

"Dahin führen mehrere Wege. Zum einen hält ein dickes Rohr aus homogenem, vergüteten Stahl mit einem Eigengewicht von etwa 4,2 Tonnen diesem Druck stand. Diese Lösung ist sehr billig, allerdings wegen des hohen Gewichts alles andere als praktisch."

'There are some possibilities to achieve this. For once the Barrel could be made from homogenous hardened steel, creating a weight of roughly 4,2 (metric) tons. This solution is rather cheap, but thanks to the high weight of the barrel, impractical.'

I don't translate the second way as it has no merit for the "discussion".

"Die dritte Möglichkeit ist ein homogenes Stahlrohr, das mit dem patentierten Verfahren der Autofrettage ein Gewicht von nur 2,7 Tonnen aufweist. Bei diesem Herstellungsverfahren wird das Rohr mit Öl gefüllt und dann mit Druck beaufschlagt bis eine "kalte" Vorreckung des Materials eintritt.
Das Rohr steht hierbei kurz vor dem Bersten, denn die Drücke auf dem öl sind höher als 10.000 bar. Danach wird der Druck schlagartig abgebaut, wodurch im Rohrquerschnitt eine von innen nach außen abnehmende Vorspannung des ansonsten homogen gebliebenen Waffenrohres entsteht. Diese Spannung muß der Gasdruck hinter dem Geschoß erst einmal überwinden, bevor er den Stahl in seiner Zugfestigkeit beansprucht. Ergebnis: Auch ein extrem schlankes und leichtes Rohr erhält auf diese Art höchste Haltbarkeit."

'The third possibility is a homogenous steel barrel, that is crafted with the (patented)
process of "Autofrettage" (it's the Gherman name dunno the English), creating a barrel
weighting roughly 2.7 (metric) tons. In the Process the barrel is filled with Oil.
The pressure is incvreased until the Barrel it self forms under the pressure in excess of
10000 bars. Thus the steel is from deminishing density from the inside to the outside
(practically it's just pressed together and as steel is rather easy to form the inside part,
where the oil pressure grips, is pushed together), whith the barrel stil being made from
one homogenous steel pipe.
This produces a barrel with a high degree of stability. Another effect is that the Barrel
rather slim and light.'

"Das Verfahren wurde von Rheinmetall entwickelt [...] denn bislang ist kein anderes Unternehmen in der Lage, dieses Verfahren gleichwertig zu kopieren."

'This process was developed by Rheinmetall [...] and so far no other corporation was able to copy the process.'

No is where the actual problem is claimed to start, as the Abrams'gun is produced not by Rheinmetall but some DoD subsidary most likely General Dynamics who produce the M1A2.

"Die Waffenstabilisierungs- und nachführeinrichtung ist NATO-weit abgestimmt auf das niedrige Rheinmetall-Kanonengewicht. Wenn nun jemand das zu bewegende Systemgewicht der rücklaufenden Teile um über 50 Prozent erhöht, kann das System nicht mehr arbeiten. In unserem Fallt heult im M1A2 "Abrams" nach Einschalten der Stabilisierung lediglich die Hydraulikhauptpumpe unter der enormen Last gequält auf und kommt ihrer Aufgabe nur zögerlich nach.
Im Gelände wippt und schlingert die Kanonenmündung mit etwa einer halben Sekunde Verzögerung den Steuerimpulsen hinterher.Sichere Schießgrundlagen sind so nicht zu bekommen"

'
'The Stabilizer is standardized NATO wide to the lower weight Rheinmetall gun.
If the weight of the barrel and it's parts (ejector etc) is now nearly 50% higher the System
won't work properly. (they seem to have first hand experience) In our case the Hydraulic pump
(which is responsible for the stabilizer) just 'screams' under the high pressure and is slow in
reacting to input.
On the move in harder terrain the gun is still stabilized but is lagging at least half a second
behind the steering impules (generated by the computer part of the stabilizer system). A save shot from the move is thus hard to achieve at best.'

"Selbst sofortige Reklamation bei der Auslieferung wurden werksseitig (General Dynamics) mit politischen Entscheidungen der US-Regierung entschuldigt. Die USA könnten es nicht hinnehmen, ein wichtiges Waffenhauptbestandteil nicht im Lande zu fertigen, dann wollten sie lieber ganz darauf verzichten."

'Even immediate protest at delivery, where rebutted by producer General Dynamics with political decision of the US government. It's inacceptable for the USA to produce such an important part of military hardware out of country, so we will do without it. (It seems Rheinmetall didn't want the m to license produce and so they made up a gun themselves)"

Hope it helps to improve matters. Just (another) quick summary: The Articel doesn't really calim that the Abrams can't shot from movement, but that it will be very hard to hit a (moving) target while being on the move itself, as the stabilizer lags behind the control impulses.
You can imagine that this has quite an impact if the tank is moving over rough terrain.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

http://www.youtube.com/watch?v=vZBN17NIzvQ

Nice video of the stabilizer of a Leopard 2A6 in action.

Popski[PPA]

Re: OOB 024 -- US Army -- M1A2 Abrams
 

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).

Re: OOB 024 -- US Army -- M1A2 Abrams
 

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.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

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

Re: OOB 024 -- US Army -- M1A2 Abrams
 

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?

Re: OOB 024 -- US Army -- M1A2 Abrams
 

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...

Re: OOB 024 -- US Army -- M1A2 Abrams
 

I think the game has US bias.. http://forum.shrapnelgames.com/image...es/biggrin.gif http://forum.shrapnelgames.com/image...es/biggrin.gif http://forum.shrapnelgames.com/image...es/biggrin.gif
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.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

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 http://forum.shrapnelgames.com/images/smilies/wink.gif

Re: OOB 024 -- US Army -- M1A2 Abrams
 

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

Re: OOB 024 -- US Army -- M1A2 Abrams
 

http://forum.shrapnelgames.com/images/smilies/shock.gif

Shouldn't that be milimeters? http://forum.shrapnelgames.com/images/smilies/wink.gif

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...

Re: OOB 024 -- US Army -- M1A2 Abrams
 

"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.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

There was Abrams recently hit in Iraq by "top attack" RKG-3M grenade. It hit the ammo compartment and ammo went off, two crew members (supposedly unbuttoned at the time) suffered 3rd degree burs.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

well and that might be another problem with the large flat turrets of the M1s. An AT-Grenade is not likely to fall off...

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Given that RKG-3 is triggered by impact, it'd trigger all the same.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Were the crew supposedly injured in the resulting ammo explosion? For this to happen in the M1, a crewman would have to have been in the process of retrieving a round from the magazine. Otherwise they should be protected by a blast door and the compartment is designed to divert the explosion upward away from the crew.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

I suspect that they simply had their heads exposed. The grenade landed on the ammo magazine, triggered the conflagration of the rounds stored, the panel popped as designed and the flames reached them.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

@Marcello: That's also my understanding of the incident.

http://www.marforres.usmc.mil/News/2...AMC_mag41.html

Re: OOB 024 -- US Army -- M1A2 Abrams
 

alright, that makes more sense.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

I'll take you up on that one, whose Chally? when? which Op? and what sort of Chally?

And do you have a source on that?

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Apparently Sunday Telegraph, May 13 2007
Article can be found in the 3rd or 4th post in following discussion, I'm too lazy to search Sunday Telegraph's site http://forum.shrapnelgames.com/images/smilies/wink.gif

Tank-net discussion regarding the incident

Re: OOB 024 -- US Army -- M1A2 Abrams
 

The Cr2 doesn't have ERA.
http://www.nao.org.uk/publications/n...-04/030460.pdf
Page 19, on that PDF.

There's no actual source for the RPG hit. However I know several tankers, and I shall ask about.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

"The Cr2 doesn't have ERA."

Wait a minute. All I can find there is "new generation of appliqué armour", which is a pretty generic description. It does not say whether ERA is included or not.
If those boxes on the lower hull front aren't ERA tiles they certainly look like them.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

trust me on this, they're not. There's pictures of RPG's embedded in them.

The attachment is a Picture of a Cr2 that got brewed up in a blue on blue incident when a HESH round went down the CO's hatch. The tank has obviously burned, and yet the armour panels are still in one piece.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

I cannot see the picture, I get the usual file not found. Still it would not rule out ERA. For a start if it is ERA it is an enclosed design, like Kontakt-5, rather than Kontakt EDZ style flying plates. So even if there is something stuck in the outer layer it does not mean that it does not work like ERA inside. Then it is not supposed to detonate as soon as something sneeze at it, for obvious reasons. It may well be non sensitive enough to resist some amount of fire.

Re: OOB 024 -- US Army -- M1A2 Abrams
 

IIRC the Russians have put once a show for the press where they did ignite the fuel cells over the fenders on a T-80U (or were that Ukrainians? Same difference in fact) and the tank remained fully operational, the ERA also didn't go off IIRC.
This being said, I frankly dunno what that thing on CR2 front is. It looks like ERA but so can NERA look like so I am waiting till somebody discloses the Truth(tm) http://forum.shrapnelgames.com/images/smilies/wink.gif

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Also take into account that for using the turret MGs the vehicle commander would need to open it's hatch. If there's enemy infantry nearby I guess it'Äs likely he would like to give additional firepower to the vehicle this way.
Now I'd say in the worst case the ammo cooking up through the release vents the fire could suffocate the whole crew by 'sucking up' the air from the turret compartment. (not to mention the serious internal burns from flaing air in the lungs...)

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Im pretty sure that the CR2 has ERA fitted to the lower front hull. Same with the CR1 during GW1.. Side Hull/Turret are Chobham Applique armour..

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Hi,

As a former M1 Abrams crewman (I've been a driver, gunner and commander) I can state quite unequivocally that the Abrams has no difficulty accurately engaging moving targets while on the move. The current Tank Table VIII (M1 individual crew qualification table) includes engaging moving and evasive targets while on the move at ranges in excess of 1500m. For example - to score 100% on an engagement against a moving & evasive tank @ 1700m, a stationary APC at 1100m and moving troops at 500m - while the M1 is moving, the crew must engage and achieve a 1st round hits on all three targets in 8 seconds or less per target for M1A1 and 6 seconds or less per target with the M1A2 (obscuration time is deducted).

Now, I'm not saying that's easy - and certainly not every crew gets 100% on every engagement like this - but it happens ,and most crews can pull off 90%+ pretty regularly (8 & 11 seconds respectively). I've done it a few times myself - I've never shot a perfect table VIII (that's 10 different engagements each 100%)I've got a few in the 900s.

Adrian

Re: OOB 024 -- US Army -- M1A2 Abrams
 

SGTGunn

It's always nice to hear from someone who has "been there, done that" It's a refreshing change from those with opinions based on books and the internet.

Would you care to comment on the top armour protection issue brought up earlier in this thread ? I am quite willing to alter OOB unit specs from what we have now when presented with good information and information from someone who has actually climbed in and out of one on a regular basis is an always welcome addition.

FYI the Challenger 2 top armour is also high. It may be too high......or not....... same as the numbers for the later Abrams so if their are any Chally 2 crewmen out there it would be nice to hear from you as well

Don

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Believe it or not, in my 4 years on the M1 I never once saw any published specs on armor thickness - presumably they were/are classified above my level. That being said, it's pretty easy, standing in the loaders hatch, to see how thick the turret roof armor is - which is to say not very. 40mm seems about right to me, though it may have actually been thinner. When the M1 was designed, there was no top attack ATGM threat, so I honestly don't think roof armor was a serious consideration. Just thick enough to keep out artillery I suspect. Sorry I don't have a more definitive answer.

Adrian

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Any spall liners or anything "Kevlarish" on the inside turret roof?

You say "M1" are you specifically refering to the early Abrams or would this also include experience with the later models? The specs in the game from a "M1 Abrams" is steel 5 which matches pretty close to your eyeball observation. Later models in the game show more protection so is your experience mostly with the early versions ?



Don

Re: OOB 024 -- US Army -- M1A2 Abrams
 

Nope, no spall liners or such, just bare steel.

My experience is with the M1-IP, and the M1A1(Heavy). The M1A2 was out when I was a tanker, but it was still new, and only 4th ID had them. The roof armor thickness on the M1-IP, M1A1 and M1A1 (Heavy) are identical. I'm pretty sure it's the same for the M1A2 and M1A2 SEP as well, unless they have added some external appliqué armor since the start of OIF (offhand I haven't seen any pictures that would seem to indicate they have). All M1 model's turrets are basically structurally identical. The changes to the armor package are all "internal" in that they don't alter the dimensions or basic structure of the tank. The A1 & A2 models have a bigger gun, so there are changes to the mount, the coax ammo box and the main gun ammo storage, but since the tank was designed from the outset to take the 120mm gun, there are no major changes to the turret itself. The A2 adds the CITV in front of the loaders hatch and changes the commanders cupola and .50 cal mount, but that's about the extant of the major differences.