Jump to content


Photo

The 2A46 125Mm Gun


  • Please log in to reply
74 replies to this topic

#1 Dawes

Dawes

    Crew

  • Members
  • PipPip
  • 2,289 posts

Posted 18 June 2012 - 1238 PM

How accurate and effective is this particular gun as compared to it's 120mm contemporaries?
  • 0

#2 Lieste

Lieste

    Crew

  • Members
  • PipPip
  • 853 posts
  • Location:Bath, UK

Posted 18 June 2012 - 1256 PM

Early models were a bit lacking by modern standards... the whole series is let down by low cost (and more recently) limited length of it's penetrators, due to the 2 part ammunition (A failing shared with the L11 and L30).

Accuracy of the early APFSDS was adequate at typical combat ranges in Europe (1-2km), and in any case, the steel penetrators were ineffective at extended ranges due to the high sensitivity of steel to impact velocity, and the higher than typical drag from the large body diameter and full-bore fins.
I think more recent APFSDS ammunition is supposed to be more accurate, possibly helped by a reduction in V0, and more consistency? The HEAT-FS and HE-FS were always more consistent than the APFSDS rounds, and I seem to recall figures that had them of comparable dispersion to, or better than NATO 120mm DM12/M830.

The long range accuracy was let down somewhat by the absence of Fire control computers until the most recent versions - with the LRF and ballistic compensator in the T72, you get something akin to firing using the auxiliary sight of a Western tank, with the target 'at a known range'. All corrections for cant, windage, lead etc needed to be added by the gunner.
  • 0

#3 bojan

bojan

    Crew

  • Members
  • PipPip
  • 10,850 posts
  • Gender:Male
  • Location:Belgrade, Serbia
  • Interests:Obscure tanks and guns.
    Obscure facts about well known tanks and guns.
    Obscure historical facts.

Posted 18 June 2012 - 1403 PM

0.21 mils HEAT
0.25 mils APFSDS
  • 0

#4 methos

methos

    Crew

  • Members
  • PipPip
  • 852 posts
  • Gender:Male

Posted 18 June 2012 - 1423 PM

The 2A46 and subsequent models has less barrel life and support less chamber pressure than the typical 120 mm smoothbore gun, but perform similar in this two aspects to the British L30 tank gun.
  • 0

#5 bojan

bojan

    Crew

  • Members
  • PipPip
  • 10,850 posts
  • Gender:Male
  • Location:Belgrade, Serbia
  • Interests:Obscure tanks and guns.
    Obscure facts about well known tanks and guns.
    Obscure historical facts.

Posted 18 June 2012 - 1627 PM

The 2A46 and subsequent models has less barrel life

Newer models are quite comparable

and support less chamber pressure...

And this also. Numbers have been posted previously.
  • 0

#6 methos

methos

    Crew

  • Members
  • PipPip
  • 852 posts
  • Gender:Male

Posted 18 June 2012 - 1645 PM

Yes... I posted them some time ago here:

2A26 & earlier 2A46 models: 5100 bar*
2A46M-1 tank gun and later models: 6500 bar*
Exp 32 M1 (became later British L30 tank gun): 6180 bar**
Rheinmetall Rh 120 L/44 (and US M256 tank gun): 7100 bar
Rheinmetall Rh 120 L/55 500 bar more than L/44 (7600 bar)
Morozov KBA3 tank gun: 6500 kgf/cm² (6374.3 bar)
Morozov KBM2 tank gun: 7200 kgf/cm²(7060 bar)


I would not call this quite comparable... like the barrel life. 1,200 vs 1,500 EFC is a significant difference, the same can be said about 6500 and 7100 bar.

Edited by methos, 18 June 2012 - 1646 PM.

  • 0

#7 bojan

bojan

    Crew

  • Members
  • PipPip
  • 10,850 posts
  • Gender:Male
  • Location:Belgrade, Serbia
  • Interests:Obscure tanks and guns.
    Obscure facts about well known tanks and guns.
    Obscure historical facts.

Posted 18 June 2012 - 1851 PM

New 2A46Msomething are 7000.
As for EFC, total EFC number does not say whole story how much EFC is every round? M829A3 at least is pretty hard on gun.

BTW, Chinese 125mm used on Pakistani Al Khalid is 1800 EFC,
  • 0

#8 methos

methos

    Crew

  • Members
  • PipPip
  • 852 posts
  • Gender:Male

Posted 19 June 2012 - 0312 AM

It could be that the Russians developed a gun with a maimum chamber pressure of 7000+ bar. But there are multiple websites claiming that the 2A46M-5, which was fitted on the recently demonstrated T-90MS, still has a maximum chamber of 6500 bar.
  • 0

#9 AdmiralB

AdmiralB

    Technical Janitor

  • Members
  • PipPip
  • 1,234 posts
  • Gender:Male
  • Location:Central Indiana

Posted 26 June 2012 - 2127 PM

Isn't chamber pressure only part of the equation? Bore diameter figures in also, right? 125mm is about 8.5% larger in bore area compared to 120mm; 6500 bar in a 125mm bore is roughly equivalent to ~7000 bar in 120mm bore with respect to force on the projo base...is it not?
  • 0

#10 methos

methos

    Crew

  • Members
  • PipPip
  • 852 posts
  • Gender:Male

Posted 27 June 2012 - 0502 AM

IIrc. pressure should already take the area (volume for gases?) into account.
  • 0

#11 Lieste

Lieste

    Crew

  • Members
  • PipPip
  • 853 posts
  • Location:Bath, UK

Posted 27 June 2012 - 0528 AM

Yup, but he is saying that work done on the projectile is F(pressure, bore area, barrel length). So a smaller weapon will either generate less muzzle impulse/energy or require a higher pressure to achieve the same.
  • 0

#12 Max H

Max H

    Crew

  • Members
  • PipPip
  • 3,656 posts
  • Gender:Male
  • Location:Dorset

Posted 27 June 2012 - 1015 AM

However, a smaller diameter bore can mean less sabot weight
  • 0

#13 bojan

bojan

    Crew

  • Members
  • PipPip
  • 10,850 posts
  • Gender:Male
  • Location:Belgrade, Serbia
  • Interests:Obscure tanks and guns.
    Obscure facts about well known tanks and guns.
    Obscure historical facts.

Posted 27 June 2012 - 1053 AM

Still larger bore is preferable other factors (propellant charge) being same, one of reasons 105mm L7 took over 20pdr, larger sabot area makes more efficient use of propellants despite being heavier.

Edited by bojan, 27 June 2012 - 1053 AM.

  • 0

#14 pikachu

pikachu

    Crew

  • Members
  • PipPip
  • 1,887 posts

Posted 27 June 2012 - 1114 AM

Still larger bore is preferable other factors (propellant charge) being same, one of reasons 105mm L7 took over 20pdr, larger sabot area makes more efficient use of propellants despite being heavier.


So is there any advantage to going even bigger? IIRC the 152.4 mm Soviet TD guns in WW2 could lob projectiles as heavy as 48 kg at 800 m/s. Given that modern sabot rounds weigh about a quarter that, would it be possible to make a "hammer of God" type sabot round weighing just half the old 152.4 mm rounds but traveling at modern APFSDS velocities without increasing chamber pressure too much?
  • 0

#15 Max H

Max H

    Crew

  • Members
  • PipPip
  • 3,656 posts
  • Gender:Male
  • Location:Dorset

Posted 27 June 2012 - 1119 AM

Like the 140mm cannon that were under development? Here's a picture of the british 140mm ammo next to the 120mm, taken by Bob Griffin IIRC
Posted Image
If only...
  • 0

#16 Ben Dejo

Ben Dejo

    Crew

  • Members
  • PipPip
  • 185 posts
  • Gender:Male

Posted 27 June 2012 - 1127 AM


Still larger bore is preferable other factors (propellant charge) being same, one of reasons 105mm L7 took over 20pdr, larger sabot area makes more efficient use of propellants despite being heavier.


So is there any advantage to going even bigger? IIRC the 152.4 mm Soviet TD guns in WW2 could lob projectiles as heavy as 48 kg at 800 m/s. Given that modern sabot rounds weigh about a quarter that, would it be possible to make a "hammer of God" type sabot round weighing just half the old 152.4 mm rounds but traveling at modern APFSDS velocities without increasing chamber pressure too much?


I would go larger than 152.4mm, or at least different...the last thing I want is to accidentally get rifled field gun or howitzer ammo for my smoothbore tank gun...not only is it embarrasing it does not work so well.
  • 0

#17 Lieste

Lieste

    Crew

  • Members
  • PipPip
  • 853 posts
  • Location:Bath, UK

Posted 27 June 2012 - 1134 AM

Nothing wrong with L11/L30 in terms of energy - "all" that is needed to dramatically improve long range performance is replacing the two-piece cartridge with a similar sized fixed cartridge with full length penetrator. M829A3 penetrator is around 50% longer than what I think is probable for the L27 ~ the longest UK rod I've been able to scale from a photo, anyway.

M829A3 ~924mm O/A, ~830mm Core, ~803mm equivalent cylinder for Odermatt (figures from TN posts past and consistent with DU weight admitted under FOI reports).
L27(?) ~690mm O/A, 565mm Core (est)
  • 0

#18 IronsightSniper

IronsightSniper

    Crew

  • Members
  • PipPip
  • 250 posts
  • Gender:Male
  • Location:California
  • Interests:Contemporary History and Antiquity History, Weapons in general, Physics, Philosophy, Political Theory, Psychology, Eating, Fighting, Observing.

Posted 27 June 2012 - 2321 PM

The 140 mm gun & shot developed by the Swiss for their Leopards achieved penetration figures of over 1 m of RHAe. There are advantages to going bigger.
  • 0

#19 methos

methos

    Crew

  • Members
  • PipPip
  • 852 posts
  • Gender:Male

Posted 28 June 2012 - 0238 AM

The 140 mm guns always have far more powder (longer catridges) than the NATO 120 mm. The two-part 125 mm ammunition has about the same amount of propellant as the NATO 120 mm gun. To achieve a similar energy output (with contemporary rounds) the 125 mm gun needs to be longer.
With increasing the diameter the amount of weight spent in the sabot will increase. So even if we increase diameter, most of the gained energy will be spent on the sabot, unless we increase the weight of the projectile - which means larger diameter or higher L/D-ratio and lower muzzle velocity.

Edited by methos, 28 June 2012 - 0238 AM.

  • 0

#20 Sebastian Balos

Sebastian Balos

    Member

  • Members
  • PipPip
  • 1,145 posts
  • Gender:Male

Posted 28 June 2012 - 0303 AM

125 mm gun would be as capable as 120 mm L55 if it would have had one-piece ammo.

120 mm might be the largest possible with human autoloader. 140 mm will need an automatic autoloader. I've seen a two piece 140 mm ammo, similar in configuration to 125 mm ammo. The projectile part is actually similar to 120 mm in length so no wonder that particular design never got operational. What is needed is a one piece ammo having a caliber larger than 120/125 mm, be it 140 mm or even larger. However, have in mind that such gun and ammo will have a considerably higher recoil energy and impuls so a smooth recoil would be needed, which will have consequences on turret and autoloader design, etc.
  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users