Challenger 2 tested with 120 mm smoothbore gun

#1
22 February 2006 JDW

Christopher F Foss
Jane's Land Forces Contributing Editor, London

Challenger 2 tested with 120 mm smoothbore gun

A British Army Challenger 2 main battle tank (MBT) armed with a hybrid German Rheinmetall 120 mm L/55 smoothbore gun has recently undergone a series of successful firing trials in the UK.

The British Army has a total of 386 BAE Systems Land Systems Challenger 2 MBTs all armed with a 120 mm L30 rifled tank gun. The UK is the only major NATO member to use a 120 mm rifled tank gun as most countries now opt for a 120 mm smoothbore weapon.

The 120 mm L30 rifled tank gun fires a depleted uranium (DU) type armour-piercing fin-stabilised discarding sabot (APFSDS) projectile that is only used in combat.

There has been no recent UK production of the 120 mm DU round, which is now out of favour with most countries, or of other 120 mm ammunition types such as smoke or high-explosive squash head (HESH).

Following a competition, the then RO Defence was awarded a GBP3.5 million plus (USD6 million) contract from the Defence Procurement Agency (DPA) for the 120 mm Smoothbore Option Technical Demonstrator Programme (SO TDP).
The programme essentially uses the German Rhein-metal! 120 mm U55 smoothbore tank gun, which is fitted into the latest German Krauss-Maffei Wegmann Leopard 2A6 MOT. So far two hybrid 120 mm U55 barrels have been supplied to the UK plus a quantity of ammunition.

Ballistically the new weapon is the same as the German 120 mm L/55 but externally can tit into the space previously occupied by the L30.
The current Challenger 2 installation retains the L30 rifled gun's cradle, gun clamp, thermal sleeve, fume extractor and muzzle reference system.
Following trials in Germany the weapon was also tested in a static mount installed on a Centurion chassis in mid-2005 and late last year was finally integrated into a Challenger 2 MBT.

Static firing trials have been conducted against a wide range of targets firing the Rheinmetall 120 mm DM53 APFSDS projectile with a conventional penetrator. These trials are understood to have shown that the DM53 gives enhanced performance over the current 120 mm CHallenger ARMament (CHARM) 3 DU round.


The first picture of the Challenger 2 MBT fitted with Rheinmetall hybrid 120 mm U55 smoothbore gun. On top of the turret (circled) is what appears to be a mounting for a 7.62 mm/12.7 mm remote-controlled weapons station
 
#2
Hmm, more toys to play with.

Question - I'm guessing that the accuracy will be lost that the rifled barrel affords. Will this prove to be a problem or is the range of the current weapon not fully utalised anyway?

OS
 
#3
there is an article in soldier mag about this.
 
#4
Any tankie tell me the difference between smoothbore and rifled in terms of accuracy? I keep on thinking my old double-barrel shotgun vs my Enfield in terms of accuracy when I think of smoothbore.
 
#5
Challengers now hold the record for the longest distance tank kills in GW1 using the Rifled barrel, i seriously cant see a smooth bore rifle being able to kill hard targets at the same distances.

Rembering that NATO smoothbore tank weapons were designed to meet the red threat on the battlefields of europe where terrain prevents long distance shooting..... but more recently we are finding ourselves in theaters of operations where being able to defeat armour over distances before they can hit ours is a massive lifesaver.

Having said all this - if you are going to use fin stablised ammo - why would you want to fire it through a rifled barrell? you DONT want it to spin

Rincewind
 
#7
Trackpen said:
What, of course, they are looking for - regardless of operational effectiveness - is logistic commonality.
Make that cost effective logistic commonality. Surely smooth bore has to be cheaper than rifled?
 
#8
Of course, this also means no Cannister, HESH, or WP.
What are you going to do next time you need to demolish a hospital in S Iraq?
Fin is only going to make tiny holes in walls, perhaps thats what they're giving you a remote controlled 12.7 HMG for......
 
#10
will make things a bit easier for tankies though ... they will be able to go on supply raids to the septic QMs as well. In fact if they take the commonality of equipment far enough, they could just steal an M1 and strip it for parts.
 
#11
Rincewind said:
Challengers now hold the record for the longest distance tank kills in GW1 using the Rifled barrel, i seriously cant see a smooth bore rifle being able to kill hard targets at the same distances.

Rembering that NATO smoothbore tank weapons were designed to meet the red threat on the battlefields of europe where terrain prevents long distance shooting..... but more recently we are finding ourselves in theaters of operations where being able to defeat armour over distances before they can hit ours is a massive lifesaver.

Having said all this - if you are going to use fin stablised ammo - why would you want to fire it through a rifled barrell? you DONT want it to spin

Rincewind
Since it was a fin round that was used for the 5.600m kill, I'm not convinced that the rifling had anything to do with it, unless the British fin round has the fins angles so that the round rotates as if it were spin-stabilised. The Abrams not killing anything at much over 4,000m is probably more due to the fact that the American designers hard-coded a 4,000m limit into the ballistic computer. The same cannon on German tanks is not subject to the same limitation, but as they've not used it in combat except on some Yugos, the theoretical is as yet unconfirmed.

NTM
 

OldSnowy

LE
Moderator
Book Reviewer
#12
I am informed by a senior Tankie that APFSDS doesn't spin - it is carefully designed so that the outside bit does, but the arrow itself doesn't. Therefore it's logical that a smoothbore could actually be more accurate than rifled, as it will reduce one layer of complexity (the bit that has to stop the dart thingy spinning).
 
#13
Thanks, was unsure how it all worked....

as for comonality - i seem to remember - we use caseless ammunition and everyone else uses cased ammo?

Rincewind
 
#14
Rincewind said:
Thanks, was unsure how it all worked....

as for comonality - i seem to remember - we use caseless ammunition and everyone else uses cased ammo?

Rincewind
From memory of playing with the Abrams a long time ago, but I seem to recall that while the ammunition is one piece, it is not fully cased: i.e. the round has a stub case and a ready-made ash tray is thrown back into the turret after firing. Basically, the US designers wanted to speed up loading, particularly with the shuttered bustle stowage, while minimising gash in the turret.
Or am I thinking of the M1 Abrams (105mm) and not the M1A1/2 (120mm)?
 
R

really?_fascinating

Guest
#16
The fin round as used has to be over engineered to allow the use of a slipping driving band in order to reduce spin. Excessive spin in a fin round would degrade terminal effect and would create instability (all to do with centre of gravity vs centre of pressure). As for other natures HE etc, it is possible to have fins for HE rounds that allow them to be fired down smoothbore barrels - Soviet 125mm ammo for example.

In essence, a smoothbore gun allows better accuracy for fin than a rifled barrel at reduced complexity.
 
#17
Well, I was always under the impression that rifled was more accurate than a smoothbore. HESH is a great round and it was this type of round that took out the Iraqi tank at over 5000m.

On top of this, what about ammo storage and the implications of going to one piece in the C2 turret?


Reckon it's another step backwards....
 
#19
spank_the_monkey_to_death said:
HESH is a great round and it was this type of round that took out the Iraqi tank at over 5000m.
Pretty common misconception. We finally sat down and worked it out over on Tank-Net, and we have the details down to the gunner's name.

Gunner: Cpl Mick Smith
TC: Lt Colonel John Sharples.
Range: 5,600m
Ammo: L-23 (Fin)

I think you're better off with the rifle, myself, but what the hey.

NTM
 
#20
really?_fascinating said:
The fin round as used has to be over engineered to allow the use of a slipping driving band in order to reduce spin. Excessive spin in a fin round would degrade terminal effect and would create instability (all to do with centre of gravity vs centre of pressure). As for other natures HE etc, it is possible to have fins for HE rounds that allow them to be fired down smoothbore barrels - Soviet 125mm ammo for example.
The problem is that the construction of the finned HE round is such that the explosive filler content of the 125mm HE round is about on the order that you would get from a much smaller rifled equivalent. (100mm or so). You get much more bang-per-round out of a rifle.

NTM
 
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