OOB 024 -- US Army -- M1A2 Abrams

[Epoletov_SPR]

The tank is accessible since 1993.
But the gun at it is established " 120mm M256 94 "!

[Marcello]

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

[mr_clark]

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

[Mobhack]

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

[Pats]

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?

[mr_clark]

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.

[Listy]

Pats said:
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?

One, Two, Three, One!

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

[Pats]

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...

[mr_clark]

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.

[PopskiPPA]

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

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

Popski[PPA]