New MBT(Leo 2, M1A2, or Challenger 2), new light tank (Stingray), or new DFSV (M8 or MGS)?

[Lance Wiebe]

The two concepts indeed do have their strengths and weaknesses.  Primarily in that the rifled gun was designed to fire both KE and CE rounds, with one of the CE rounds having an Infantry support capability.  HESH is great for forticications, buildings and so on, and the smoothbores lack this capability.

There is no denying that the smoothbore was designed to kill armour, and nothing else.  It is telling that 25 years after the weapon first appeared, the French, Germans, and Americans are still developing a round with HE capabilities.  The primary problem with all of them is stability and accuracy.  None of the rounds 120mm HE projectiles, including the French round, have met the minimum requirements for acceptance, despite being in development for years.

However, the argument is moot.  The excellent CHARM3, the most accurate and powerful 120mm tank gun out there, will soon beome a footnote in history.  And, someday, technology will develop a round that is almost as good as the HESH/HEP/HE rounds fired from rifled barrels for the smoothbore. 

There is one thing that makes me wonder about the US approach, though.  And that is there call for the various 105 mm rounds for the MGS.  Maybe they will use the 105 to support the Infantry, and give up on developing an HE round for the 120?

 

[12alfa]

When the 120 sb have been is service and the same amount of upgrades to the ammo as the Charm/rifled tubes, will we say the charm is still the best?

The Charm system to a great degree was developed before the wall came down and deployed after a long r&d stage. If we wait for the same amount of time with the 120 sb I think we will see a greater improvement in its use and different ammo types.Also a rifled tube can't fire a ATGM , can it?

Can't argue that it;s a great tube slaved to one of the best FCS, but the ammo that is now in question, for them to switch the system because of supplier problems in my book is it's downfall. This is not going to happen to the smoothbores.

Is the spun Ke round less effective than a non-spun round, I mean it's more stable in flight and at point of impact is better/ more precise than a spun round?

 

[Lance Wiebe]

The reason the Brits rejected smoothbore in the first place was their belief that tanks had a secondary task to support infantry complete their tasks.  It hasn't been cheap for them to keep developing the gun and ammunition as they have, with no hope of export orders.    Now, with their cutbacks, it has become impossible.  At least they are calling for the L55, and not the L44.  The problem there is that some of the ammo developed for the L55 is not compatable with the L44, so using some US ammunitions is out of the equation.

The KE round fired from both the rifled and smoothbore cannons are fin stabilised, and do not spin.  The APFSDS designed for rifled barrels has a slip ring, so the ring bites the lands and spins, while the projectile doesn't spin. 

Some of the reasons the Charm 3 is so powerful is that it uses new technology in the construction of the barrel, I'm not sure if the Brits will share this technology or not, but I think that if they license build the L55, you'll see some interesting developments from RO fairly shortly.  This new construction allows much greater chamber pressures, so the designers came up with a slip ring that really bites the lands, and provides greater obturation than was achievable before.  This results in a round with much higher KE than is achievable with smoothbores.  Smoothbores, inherent to their design, cannot quite achieve the obturation rifled barrells can.

I find it interesting that the UK, with its small industry, has achieved so much in tank design.  Highlights include the first truly stabilised main gun, spaced armour, Chobham armour, and now the as yet unfielded (?) electric armour.

 

[Smoothbore]

A Challenger 1 (armed with a 120 mm L11A5 rifled cannont) took the record for the longest range kill by a tank in the first Gulf War, destroying a T-55 at a range of about 5 km with a HESH round.
A remarkable distance considering scintillation of the near-surface air.

 

[Lance Wiebe]

Are you sure it was a HESH round?   I haven't seen proof either way, but this web site claims it was an <a href=http://www.army-technology.com/contractors/ammunition/apfsds.htm>APFSDS</a> round.

By the way, the link has a good explanation of APFSDS, while the parent site itself has some good, unclassified information.   http://www.army-technology.com/

 

[Smoothbore]

I would consider Army Technology a more reliable source compared to where I got my specs from. It was most likely the L27A1 CHARM round.

Now back to the original question:
Both tanks (I'm assuming we're talking about the SEP version of the M1A2) are world leaders by which other vehicles are assessed, both are equally matched in terms of optics and fire control including independent thermal viewers on both vehicles permitting hunter-killer capability. The M1A2 SEP has a slight advantage in armour protection which includes both Chobham- type composite layers and DU inserts that are 2,5x denser than high grade steel. Challengers used in Op Telic have better side protection which incorporate ERA panels. The Abrams outpaces the Chally in mobility tests. The gas turbine is also stealthy and emits no visible exhaust.

 

[12alfa]

Are you sure it was a HESH round?   I haven't seen proof either way, but this web site claims it was an <a href=http://www.army-technology.com/contractors/ammunition/apfsds.htm>APFSDS</a> round.

By the way, the link has a good explanation of APFSDS, while the parent site itself has some good, unclassified information.   http://www.army-technology.com/

I read a report on the hit. Seems the gunner was "pestering" the c/c to let him take a shot, finnaly the commander decided to issue that famous FIRE order, the rest is now history. This is King of rifled systems, and fron the country who gave us the first Tank.And from them will come the 1st plastic AFV also.

Think I read it was hesh aslo, my mind is going ya know...

 

[Lance Wiebe]

So many advances from Great Britain in the field of armour.

The first true sabot round, spaced armour, composite armour, now "electric" armour

It's too bad that they couldn't develop a decent power pack for so long.  They led, and lead, the west in passive armour protection, and the 17 pounder, 20 pounder and 105 were far and away the best tank guns of their time.  But.......The Chieftan's power pack was a disgrace, and an embarrassment.  The latest one is not bad, but light years away from the German packs.

 

[Yard Ape]

Could a German power pack fit/function in a Brit tank?

 

[12alfa]

The KE round fired from both the rifled and smoothbore cannons are fin stabilised, and do not spin.   The APFSDS designed for rifled barrels has a slip ring, so the ring bites the lands and spins, while the projectile doesn't spin.  

Are  you saying that the round (sabot,penetrator, and slip ring) are not spining to a small degree while traveling down the tube in a rifled system?
I can't see a non-moving object in a rifled tube, even with slip rings, after the initial explosion keeping up to the spin that is generated by the rifing to keep the dart perfectly level, am I making a sence?

I agree that after the seperation of the sabots, the dart will in distance will start to fly without spin due to the fins. But from what I have read and seen in a Charm system firing , the sabots fly off in a matter that loks like they are spining after leaving the tube, unlike the effect of a sabot out of a sb as to falling off without and noticible spining effect.

Granted this spin is small, but is it still there?

 

[Smoothbore]

Agreed, the Brits have advanced steel machining technology, they first introduced electro-slag refined steel in the production of the L11 cannon for the Chieftain. They however lack sophistication in optics and FCS (Challenger 2 uses a French thermal imager from Sagem). And yes, both the Leyland 60 (Chieftain) and the Perkins CV12 TCA (Challenger) are not leading edge powerpacks, it all started with that damned Centurion.

Could a German power pack fit/function in a Brit tank?

There was a prototype called the Vickers Mk 7 which mounted a turret similar to todays Challenger 2 with the chassis of a Leopard 2. It didn't sell though.
If you're asking whether it is possible to squeeze a foreign power-pack into the Challenger chassis I believe thats the whole point of the updated Challenger 2E export variant, which features a 1500 hp MTU 883 diesel engine.

It's all here:
http://www.army-technology.com/projects/challenger2/

 

[TANKIE]

Dont worry 2 much about it lads chally 2 proved itself in the Gulf and abrams tried 2 follow but couldnt.
RPG rounds were bouncing off chally 2 side and just making the paint while the abrams were getting taking out by a rpg in the side .

How many tanks were lost in the Gulf war ,1 chally 2 due to blue on blue , does anyone know how many abrams were knocked out ??????    :skull:

 

[childs56]

I thought that the fin stab sabot rd fired out of a rifled barrel did spin. The reason for the fins was to stabilize the penetrator rod to keep it form tumbling head over heals not to keep it from spinning. Spinnig as I recall has a more accurate affect on range due to its increase in stablity of the actual rod or rd itself. I might  be wrong about this.

 

[Lance Wiebe]

You are wrong.

APFSDS rounds do not spin, the slip ring negates the grooves in the barrel, and the round emerges with no spin. 

Spin is applied to rounds for stability reasons, but in the case of KE rounds, spin actually detracts from penetration performance, which is why the move to develop fin stabilized rounds developed in the late '70s.

 

[childs56]

I just re-read the info I had on penetrator rods and it states that early rods used by the Brits had a spin on them and that they were less effective then more modern ones(not as much range but more accuracy) and that the new rds fired from the rifled barrel does have some spin but it is negligible because of the slip rings. I found a site on the US ammunition site and it is quite informative except that you cant access it now because of security reasons.

 

[Lance Wiebe]

Yes, the original APDS rounds achieved their stability by spinning, very much like a rifle bullet.  But the fin stabilised rounds fly more like an arrow, not a bullet, if you want a simple analogy.  While upon exiting the barrel, a APFSDS round may have some very slight spin, the spin is gone by the time the sabots are released.

 

[12alfa]

  While upon exiting the barrel, a APFSDS round may have some very slight spin, the spin is gone by the time the sabots are released.

I have a paper that says
"The
British 120mm APFSDS has its spin largely cancelled by the slip rings
on the sabot, but even so its still doing 1,200 rpm at the muzzle.
The
penetrator does spin, but very slowly, maybe 1 rps, just enough to smooth
out aerodynamic irregularities.   The development of fin-stabilized
long-rod penetrators is one of the things that has made smoothbore main
guns more fashionable than rifled main guns recently."


Is this wrong?

 

[Lance Wiebe]

I can't imagine where they got 1200 rpm at the muzzle.  LFTEU has some really good high speed photography taken of APFSDS rounds exiting the barrel.  Great training aid!

Like I said earlier, spin degrades the performance of both HEAT and APFSDS rounds, (here I am talking terminal effects).  The reason that rifled barrels are kept by the British is that they can fire spin-stabilised rounds for Infantry support, such as HESH and smoke.  Smoothbores cannot fire HESH and smoke rounds.  Therefore, the APFSDS rounds fired from rifled barrels have quite a bit higher complexity (and cost) to negate the spin.

There is also some performance loss.  A rifled barrel, naturally, converts some of the energy of the propellant to spin.  There is a natural drag on the round to achieve this.  Even using teflon slip rings, there is some energy loss when compared to a smoothbore gun.  Increasing propellant to maintain velocity also has the disadvantage of increasing barrel wear, and causes greater consequences of fire.  And we all know the law of physics, where energy is greatly dependant on speed.  (energy=mass X velocity squared).

The British have resigned themselves to the smoothbore, which means that they are losing their Infantry support ammunition.  The cost of being the only users of rifled 120 finally became too much, in terms of R&D.

The 105 in also dead, in terms of development of new rounds.  Nobody is designing new tanks with rifled 105, so it is doubtful we'll see any changes to our ammunition, unless it is done by SNC.

 

[12alfa]

Just trying to understand this spinning more. The paper is from  Robert F. McCoy's "Modern Exterior Ballistics" and what I'm trying to get a grip on is "precession".
As you know this has some effect on the rod at impact. Thus my post on the rifled tube having "spin". Now you say that it does not, you see why in a bit confused?

Most data I have or read ,reports some spin, on both in the barrel and as the rod moves downrange to impact. Given this rotation is small, but is there I believe to stabilise the rod from precession .
My question is therefore , does the rod spin? Does not the fins have machining on them to produce this "spin", meaning the fins edges are not square. I don't know if i can explain this clearly enough to find a answer.

Afv's and ammo is a hobby of mine and obtaining info is a on going quest.

Is the 120 on the new India tank a rifled one, have seen post of it being so, this is a new tube and seems to point to more development in the rifled tube area.
Cheers.

 

[Lance Wiebe]

Grrr.

I answered this in some detail, but when I hit "post", my whole computer froze up on me.  Stupid computers.  Can we get together and discuss this over a beer instead?

Now, you're going to get the condensed version. 

I am going to take a wild guess, and state that the book you have predates the latest long rod penetrators.  While precession was desirable in all rounds, except for HEAT, todays long rod penetrators (the ones approaching an L ratio of 20:1) have to defeat this once desirable trait.  The problem with these rounds is that they do not spin in a nice manner, instead, the nose yaws in a circle as it flies down range.  This is obviously less than desirable.  Huge amount of research time has fixed this in the older rounds, but the greater the L ratio, the worse the problem.  Experimental rounds with an L ratio of 40:1 have been fired, the only way possible to stalize them is to have no spin whatsover.  They cannot, therefore, be fired from rifled barrels, even with slip rings.

High speed photography displays the tendency of APFS rounds fired from rifled barrels to yaw to the right and down, the seperation of the sabot tends to help straighten the round, the fins do the rest.  The fins negate the spin of the round, so while a FS round hitting a target  at closer ranges may have some spin, it is negligable.

BTW, the yaw I was talking about earlier means that if we fire at a target closer than 400M with our current weapon/ammo combination, the round will not be effective, as it will not hit nose first.