Aces High Bulletin Board

General Forums => The O' Club => Topic started by: 63tb on July 14, 2008, 07:59:34 PM

Title: Modern tank cannons - smooth vs rifled
Post by: 63tb on July 14, 2008, 07:59:34 PM
Folks,

I was watching Top Gear and they mentioned that a Challenger II tank had a rifled main gun that "can actually hit something" unlike smooth bore American tanks that can "hit something over there".

I was surprised at this. I thought all tank guns are rifled. Do any other tanks use smooth bore main guns? Why would you use a smooth bore?

63tb
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Hornet33 on July 14, 2008, 08:09:42 PM
The M1A1, Leoperd II, and Leclerk all use a 120mm smooth bore cannon. In fact the M1A1 cannon is of German design originaly for the Leoperd II. The Challenger is the only other tank on the planet in the same class as the others that uses a rifled cannon. If I'm not mistaken the Russian T-72-80-90 series tanks all use a smooth bore 125mm cannon as well.

The smooth bore is better for firing SABOT rounds with since the penetrator is nothing more than a large dart that destroys the target with kinetic energy instead of explosives. If you spin a SABOT round it's actually not as acurate.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Latrobe on July 14, 2008, 08:10:01 PM
The british use the Rifled bore and have better accuracy than most other tanks, but they lack higher velocity because of it. I think mostly every other country uses smooth bore because it gives you better penetration (because of higher velocity), but with a lack of accuracy compared to rifled. The American M1 Abrams though is just so technologically advanced I thinks its accurate enough to hit anything the Challenger I and II can.


Though I'm no expert I could be wrong with some of this info.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Maverick on July 14, 2008, 10:10:55 PM
This is kind of silly. If you really want to see what the accuracy capability of the smooth bore tank cannon you just might want to read the description of the 73 Easting battle in GW1. Those are AFAIK the longest ranged engagements on the battlefield for tanks. The range was in excess of 3700 meters and the hit ratio was in excess of 90%. It was also a killing range for the gun.

FWIW the main gun battle sight range of the 105mm tank round (sabot) on the M60 tank was 1600 to 1800 meters and the range you could expect a kill or penetration was 1200 meters assuming the target was the front of a soviet T72. The later M60A3 with the gun upgrades could expect to hit out past that range easily but the 105 doesn't have the penetration capability of the 120mm.

With the proper ammo, targeting system and gun, the smooth-bore gets more velocity, flatter trajectory and shorter flight time than a rifled bore. It also doesn't burn out near as fast either. It will certainly do the job at a farther range than will the rifled bore as has been demonstrated.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: 63tb on July 14, 2008, 10:22:24 PM
What gives the smooth bore round its stability? Wasn't that the advantage of rifling?

63tb
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Maverick on July 14, 2008, 10:32:09 PM
The sabot round in the 120 is fin stabilized. It looks kind of like a stubby crossbow bolt. A very heavy one.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Jester on July 14, 2008, 11:13:45 PM
MK.735 SABOT ROUND from the 120mm Gun on the M1A2
(https://www.mysticarmynavy.com/images/sabot2.jpg)

What the SABOT Round Looks like:
(http://www.army-guide.com/eng/images/060801_GermanADFSDS_1.jpg)

Projectile Dart leaving the SABOT casing after firing:
(http://www.frfrogspad.com/sabot.jpg)
Title: Re: Modern tank cannons - smooth vs rifled
Post by: ZetaNine on July 14, 2008, 11:26:55 PM
one point of contention that I have always has when it comes to military weapons demonstration films...is that they always show the target at impact....large explosion and all....but they rarely focus on the what the target looks like when the smoke clears...

that...and...does anyone have any filmed footage/images of sabot penetrations...and the resulting carnage inside the vehicle?
Title: Re: Modern tank cannons - smooth vs rifled
Post by: MORAY37 on July 15, 2008, 03:05:38 AM
The british use the Rifled bore and have better accuracy than most other tanks, but they lack higher velocity because of it. I think mostly every other country uses smooth bore because it gives you better penetration (because of higher velocity), but with a lack of accuracy compared to rifled. The American M1 Abrams though is just so technologically advanced I thinks its accurate enough to hit anything the Challenger I and II can.


Though I'm no expert I could be wrong with some of this info.


Respectfully, I would disagree.  Challenger 2 is probably the best all round tank in existence, currently.  It was the only armored vehicle in both gulf wars to not lose a single tank to enemy fire.  (in one engagement an Iraqi AT missile hit one dead on, only blowing off the gunner's sight.  The tank drove away and was back in action in 4 hours.  There are also repeated examples of the Challenger 2 taking dozens of hits from man portable AT weapons and figting on.)

The Challenger also has the longest confirmed kill of another tank..... 5,100 meters.  Abrams? Forget about it after 2000 meters....it's not hitting.

The only thing that doesn't make it better than the M1a2 is it was only manufactured in 265 examples. 
Title: Re: Modern tank cannons - smooth vs rifled
Post by: rabbidrabbit on July 15, 2008, 11:14:49 AM
Respectfully, what makes you think you have any clue about this?  Your statements are clearly contradicted by observable fact.






Respectfully, I would disagree.  Challenger 2 is probably the best all round tank in existence, currently.  It was the only armored vehicle in both gulf wars to not lose a single tank to enemy fire.  (in one engagement an Iraqi AT missile hit one dead on, only blowing off the gunner's sight.  The tank drove away and was back in action in 4 hours.  There are also repeated examples of the Challenger 2 taking dozens of hits from man portable AT weapons and figting on.)

The Challenger also has the longest confirmed kill of another tank..... 5,100 meters.  Abrams? Forget about it after 2000 meters....it's not hitting.

The only thing that doesn't make it better than the M1a2 is it was only manufactured in 265 examples. 
Title: Re: Modern tank cannons - smooth vs rifled
Post by: slipknot on July 15, 2008, 11:29:38 AM
Top Gear is a fun show, but they often substitute humorous proclaimations for facts. If they can do it at the expense of an American machine, they will. Jeremy Clarkson, for all his talent, probably knows as much about modern weaponary as I do about high end women's footwear.

Flaunting this ignorance in a confident and mocking tone, and putting the British above the Americans in the process, is better than drugs for him. He does the same thing when comparing cars, except that he actually knows a thing or two about cars. Here it's just absurd.

The Americans, as well as the Russians and whoever else uses sooth bore technology does so for a reason--and these reasons were mentioned already. Departing from the rifled barrel technology would not have been done on a whim. Smoothbore guns fire the sabot round, which requires no rifling--as mentioned. They also fire actively guided munitions, which can autocorrect their trajectory.

The concept of gyroscopic stabilization is in its 3rd century, and it should come as no surprise that new technologies are being implemented to improve upon it. Just because the Brits are sticking to a method that's older than the United States doesn't mean they're doing it right.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: GtoRA2 on July 15, 2008, 11:38:29 AM
Yeah, I think Mavs post has more accuracy then morays...... Mav has some inside knowledge!  :D
Title: Re: Modern tank cannons - smooth vs rifled
Post by: thrila on July 15, 2008, 12:12:21 PM
More importantly, the challenger comes with tea making facilities as standard.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: 2bighorn on July 15, 2008, 12:18:13 PM
Rifled gun was requirement due to older types of ammo Brits wanted to use with Challenger.
Currently, Challenger is undergoing several update programs, among others, rifled guns are going to be replaced by smooth bore guns.


Quote from: Janes
The Challenger Lethality Improvement Programme (CLIP),
which includes the replacement of the current 120 mm L30 series rifled tank gun with a 120 mm L/55 smoothbore gun, will be rolled into the C2 CSP. The FSG has been funding CLIP for several years, and the first unmanned firing of the weapon installed in a Challenger 2 MBT took place in early 2006.

Source: http://www.janes.com/news/defence/systems/jdw/jdw070525_1_n.shtml
Title: Re: Modern tank cannons - smooth vs rifled
Post by: 68Wooley on July 15, 2008, 12:38:13 PM
Rifled gun was requirement due to older types of ammo Brits wanted to use with Challenger.
Currently, Challenger is undergoing several update programs, among others, rifled guns are going to be replaced by smooth bore guns.


Source: http://www.janes.com/news/defence/systems/jdw/jdw070525_1_n.shtml

Beat me to it. The 120mm A30 cannon on Challenger 2 can fire HESH rounds which have a longer range than its APFSDS round. The HESH round is also better when you want to blow stuff like buildings up rather than turn the contents of an armoured vehicle to mush.

To be honest, you could argue the relative merits of Challenger 2, Leopard 2, Le Clerk and Abrams all day and not reach consensus - they're all good, evenly matched tanks. However, in the interests of adding a bit of nationalistic jingoism and keeping the thread interesting , I'll say this:

1. The only thing to have ever killed a Challenger is err, another Challenger. This is relatively unique in the British army. Traditionally it is the US Air Force that destroys our armoured vehicles.

2. The Abrams, like the M60 before it, originally used a British Gun. It now uses a Geman gun. It also uses armour developed by the British. Which begs the question - isn't the M1 really just a European tank with a gas-guzzling turbine engine stuck in the back?

 :noid

Title: Re: Modern tank cannons - smooth vs rifled
Post by: slipknot on July 15, 2008, 12:46:31 PM
Which begs the question - isn't the M1 really just a European tank with a gas-guzzling turbine engine stuck in the back?

No more than the US is just e European country with some Mexicans cutting the grass.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: GtoRA2 on July 15, 2008, 12:54:24 PM
Didn't we improve on the Armor, by incorperating depleted uranium in it on the M1?
Title: Re: Modern tank cannons - smooth vs rifled
Post by: evenhaim on July 15, 2008, 01:02:44 PM
Our merkava tanks uses a similiar smoothbore gun to what the brits use, and they work just fine :)
Title: Re: Modern tank cannons - smooth vs rifled
Post by: mietla on July 15, 2008, 01:34:51 PM

It was the only armored vehicle in both gulf wars to not lose a single tank to enemy fire.

How many have you deployed? If you had two Challengers among thousands of M1, what was a chance of being even targeted.

Quote
The Challenger also has the longest confirmed kill of another tank..... 5,100 meters.  Abrams? Forget about it after 2000 meters....it's not hitting.
 

I've read reports of M1 engaging Iraqi tanks at 3000-4000 meters and killing them with ease. Some Iraqi tank were even killed while they were hidden behind the sand.

Title: Re: Modern tank cannons - smooth vs rifled
Post by: 63tb on July 15, 2008, 06:50:43 PM
Thanks for all the great info!

Can a smooth bore gun only fire a sabot round?

63tb
Title: Re: Modern tank cannons - smooth vs rifled
Post by: 33Vortex on July 15, 2008, 06:55:39 PM
SABOT rounds is in the sub-caliber category. There are similar projectiles for small-arms. Like the Barrett .50 cal can fire sub-caliber rounds to achieve high-velocity, flat-trajectory ballistics, much like a tank gun actually. In order to hit targets at extreme range with great accuracy.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: GtoRA2 on July 15, 2008, 07:07:10 PM
Thanks for all the great info!

Can a smooth bore gun only fire a sabot round?

63tb

The gun in the M1 can fire sabot and Heat rounds and I think the Army has a HE round in the works.   
Title: Re: Modern tank cannons - smooth vs rifled
Post by: bustr on July 15, 2008, 07:31:48 PM
120mm M830 HEAT-MP-T   
Chemical Energy Anti-Tank Multi Purpose Ammunition

The M830 High Explosive Anti-Tank - Multipurpose - Tracer (HEAT-MP-T) service round for the smoothbore 120mm combustible cartridge case tank ammunition employs a full diameter shaped charge to defeat a wide spectrum of targets. Extremely effective against buildings and bunkers, as well as armored vehicles and other targets, the M830 serves as the companion ammunition to the kinetic energy M829 series anti-tank munition. The M830s safe and reliable fuzing ensures detonation on frontal impact or graze. The combustible cartridge case has proven to be safe, rugged and capable of withstanding the rigors of field service.

Look here for a full line up of 120mm rounds for the M1A2 tank.

http://www.gd-ots.com/sitepages/dirfire.html


 
Title: Re: Modern tank cannons - smooth vs rifled
Post by: hlbly on July 15, 2008, 11:52:34 PM
If you look historically the germans make the best guns . The brits make the best armor , and the US makes the best automotive systems . The isrealis just improve everything .
Title: Re: Modern tank cannons - smooth vs rifled
Post by: AquaShrimp on July 16, 2008, 06:26:34 AM
The M1 uses a 122mm smoothbore Rhinemetal cannon.  Rifled barrels can wear out extremely quickly.  The Russians actually had to carry extra barrels with them into battle as their rifled cannons were wearing out at an extremely quick rate (Post-afghanistan, not exactly which conflict this was, in the desert some where). 
Title: Re: Modern tank cannons - smooth vs rifled
Post by: 33Vortex on July 16, 2008, 07:40:28 AM
Chechnya.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Hornet33 on July 16, 2008, 07:59:57 AM
M1 ABRAMS ARMAMENT
The main armament is the 120mm M256 smoothbore gun, developed by Rheinmetall Waffe Munition GmbH of Germany. The 120mm gun fires the following ammunition: the M865 TPCSDS-T and M831 TP-T training rounds, the M8300 HEAT-MP-T and the M829 APFSDS-T which includes a depleted uranium penetrator. Textron Systems provides the Cadillac Gage gun turret drive stabilisation system.

The commander has a 12.7mm Browning M2 machine gun and the loader has a 7.62mm M240 machine gun. A 7.62mm M240 machine gun is also mounted coaxially on the right hand side of the main armament.

Title: Re: Modern tank cannons - smooth vs rifled
Post by: Hornet33 on July 16, 2008, 08:12:17 AM
The M1 uses a 122mm smoothbore Rhinemetal cannon.  Rifled barrels can wear out extremely quickly.  The Russians actually had to carry extra barrels with them into battle as their rifled cannons were wearing out at an extremely quick rate (Post-afghanistan, not exactly which conflict this was, in the desert some where). 

See my above post. 120MM gun not 122mm.

Also the Soviets last tank that had a rifled barrel was the T-54/55. That had a 100mm rifled main gun. The T-64/72/80/90 ALL use a 125mm smooth bore main gun, the T-62 used a 115mm smooth bore main gun, so I don't know what tanks they had that they were carrying extra barrels into battle. Also changing the main gun tube on a tank is NOT something the crew can do on their own, and is NOT something you stop and do in the middle of a battle. Also the most commonly used tank by the Soviets in Afghanistan was the T-64. The Soviets supplied old T-55's to Afghan Army units. Desert Storm the Iraqi's were using T-62's T-72's for the most part. Some units were equipped with the old T-55's, but I never saw an Iraqi tank with a spare barrel strapped on the side and I saw ALOT of blown up tanks over there.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: 2bighorn on July 16, 2008, 11:13:12 AM
Can a smooth bore gun only fire a sabot round?

Both, rifled and smooth bore guns, fire loads of different ammo types, from APFSDS, HEAT, HEFRAG, etc, all the way to guided missiles.

The reason why smooth bore guns are more common, is development of armor. Composite armor proved a bit much for shaped charge rounds, so they went back to kinetic penetrators, for which very high muzzle velocity is a must and that is easier to achieve with smooth bore guns.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Fishu on July 16, 2008, 11:31:17 AM
Quote from: GtoRA
The gun in the M1 can fire sabot and Heat rounds and I think the Army has a HE round in the works

They just need to supply the rounds to the crews first. Anti-personel capability of Abrams has been worse in Iraq than it should be.


US makes the best automotive systems . The isrealis just improve everything .

You call the poor suspension and gas guzzling engines of the US cars as the best automotive systems? The cars might be manly, but the systems hasn't been as good until the very recent years, though often suffering from design faults.

I'd say the US takes the israelis place as the improver of everything, even israeli inventions :)

The most reliable automotive systems seem to come from Japan - their cars can be seen on the roads far longer than any western car. Mercedes used to be the innovator of automotive systems, but I haven't seen many innovations recently.

Title: Re: Modern tank cannons - smooth vs rifled
Post by: 33Vortex on July 16, 2008, 11:53:57 AM
See my above post. 120MM gun not 122mm.

Also the Soviets last tank that had a rifled barrel was the T-54/55. That had a 100mm rifled main gun. The T-64/72/80/90 ALL use a 125mm smooth bore main gun, the T-62 used a 115mm smooth bore main gun, so I don't know what tanks they had that they were carrying extra barrels into battle. Also changing the main gun tube on a tank is NOT something the crew can do on their own, and is NOT something you stop and do in the middle of a battle. Also the most commonly used tank by the Soviets in Afghanistan was the T-64. The Soviets supplied old T-55's to Afghan Army units. Desert Storm the Iraqi's were using T-62's T-72's for the most part. Some units were equipped with the old T-55's, but I never saw an Iraqi tank with a spare barrel strapped on the side and I saw ALOT of blown up tanks over there.

Perhaps he was thinking of the BMP, BRDM or some other armored vehicle? That's a completely different story.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Maverick on July 16, 2008, 05:52:21 PM
The twin military experts fishu and shrimp have been conspiring again to print the "real" truth as they see it.  :rolleyes:

Replacing a main gun tube is not field level maintenance. It is never done in the field nor at front line areas. Not only is it a piece of equipment weighing more than a "couple pounds" it has to be integrated with the gun system. It's not like swapping a barrel on a machine gun which is an area weapon BTW, not an accurate point weapon.

Anti personnel weapons on the M1 are the MG's that were installed in and on it. They work fine. The main target of a tank is other armor, not troops in the battle field, that is why armor is not employed separately but as a combined arms unit with infantry. Infantry protects the tanks from the infantry and the tanks protect the infantry from other tanks and armored vehicles. They also add additional direct fire to the enemy positions and troops. HEAT rounds work as explosive rounds since they create overpressure and frags as well as an armor penetration device. Armor is a shock weapon system not a primary anti infantry system.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Bodhi on July 16, 2008, 06:00:44 PM


The most reliable automotive systems seem to come from Japan - their cars can be seen on the roads far longer than any western car.




(http://www.eastohiocoolcars.com/Chevy/1940%20Chevy%20Delux_A4.jpg)
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Mustaine on August 19, 2008, 11:16:16 PM
There's a "new" thread about this same topic, posting the same video

http://bbs.hitechcreations.com/smf/index.php/topic,244641.0.html

Guess it needs the same "you are dumb and ignorant guys who like to suckle Jeremy Clarkson" smack down as this one.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Motherland on August 19, 2008, 11:20:32 PM
lmao, it's not about that. That's just one little comment in the beginning of the video. Not the subject of the thread...
Title: Re: Modern tank cannons - smooth vs rifled
Post by: bj229r on August 19, 2008, 11:21:45 PM
Beat me to it. The 120mm A30 cannon on Challenger 2 can fire HESH rounds which have a longer range than its APFSDS round. The HESH round is also better when you want to blow stuff like buildings up rather than turn the contents of an armoured vehicle to mush.

To be honest, you could argue the relative merits of Challenger 2, Leopard 2, Le Clerk and Abrams all day and not reach consensus - they're all good, evenly matched tanks. However, in the interests of adding a bit of nationalistic jingoism and keeping the thread interesting , I'll say this:

1. The only thing to have ever killed a Challenger is err, another Challenger. This is relatively unique in the British army. Traditionally it is the US Air Force that destroys our armoured vehicles.

2. The Abrams, like the M60 before it, originally used a British Gun. It now uses a Geman gun. It also uses armour developed by the British. Which begs the question - isn't the M1 really just a European tank with a gas-guzzling turbine engine stuck in the back?

 :noid


Harleys have German pistons :aok (at least they did 10 years ago).......I bet the Brit gun leaked oil.....
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Elfie on August 20, 2008, 01:05:33 AM
Quote
Both, rifled and smooth bore guns, fire loads of different ammo types, from APFSDS, HEAT, HEFRAG, etc, all the way to guided missiles.

Iirc, only smooth bore guns fire guided missiles.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: MrRiplEy[H] on August 20, 2008, 12:45:00 PM
The twin military experts fishu and shrimp have been conspiring again to print the "real" truth as they see it.  :rolleyes:

Replacing a main gun tube is not field level maintenance. It is never done in the field nor at front line areas. Not only is it a piece of equipment weighing more than a "couple pounds" it has to be integrated with the gun system. It's not like swapping a barrel on a machine gun which is an area weapon BTW, not an accurate point weapon.

Anti personnel weapons on the M1 are the MG's that were installed in and on it. They work fine. The main target of a tank is other armor, not troops in the battle field, that is why armor is not employed separately but as a combined arms unit with infantry. Infantry protects the tanks from the infantry and the tanks protect the infantry from other tanks and armored vehicles. They also add additional direct fire to the enemy positions and troops. HEAT rounds work as explosive rounds since they create overpressure and frags as well as an armor penetration device. Armor is a shock weapon system not a primary anti infantry system.

T80 Maintenance and repair

High manufacturing quality and design peculiarities of the tank have made the tank easy in maintenance and repair:

    * maintainability of the power pack has been achieved due to the optimal building block design. Time required for the replacement of the tank power pack in the field constitutes only 3 hours;
    * the application of the quick disconnecting connection gun tube with its breech allows to replace the gun tube in the field conditions without dismantling the gun from the tank turret;
    * the fire control system and the armament control complex have the built - in control and collimation system;
    * engine air intake device design on T-80U tank ensures air dustiness de-crease at its intake into the engine in more than 10 times what in combination with the unique system of automatic dust removal from the engine setting elements guarantees engine reliable work at any air dustiness without maintenance. This level of air cleaning was proved by the tests in the deserts of Middle Asia and desert Tarr;
    * fuel and oil systems' elements are made of stainless steel what ensures their high corrosion durability;
    * T-80U tank is fueled by the closed stream through one filling throat besides during the filling up process fuel undergoes additional cleaning coming through the special filter. This makes maintenance much easier and excludes dust and moisture getting inside the fuel tanks;
    * auxiliary power pack allows to carry out storage batteries maintenance and charging, all systems and complexes functioning check and maintenance without starting the main engine what is especially important while conducting the works indoors.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Angus on August 21, 2008, 09:22:48 AM
That is not an M1, and the T's of any brand had a bad day against the Challenger.
But....is it the weapon, or is it the man behind it?

p.s. The smooth bore can fire longer rounds, so that means heavier for the same width of barrel. With a shell equally short, the rifled barrel will be more accurate. There is a reason for your rifle being....rifled  :D
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Elfie on August 21, 2008, 09:29:52 AM
Quote
With a shell equally short, the rifled barrel will be more accurate.

Unless you are firing Sabot rounds, then the smooth bore will be more accurate.  The fins on Sabot rounds stabilize the round in flight so the rifling isn't needed, or wanted even.

Quote
There is a reason for your rifle being....rifled

The rifling imparts a spin to the projectile which stabilizes it in flight and makes it more accurate.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Chalenge on August 21, 2008, 09:41:34 AM
The most reliable automotive systems seem to come from Japan - their cars can be seen on the roads far longer than any western car. Mercedes used to be the innovator of automotive systems, but I haven't seen many innovations recently.

I think there will always be amazing examples of machines that outlive their designed lifespan. I have an Uncle that still owns the first car he bought brand new off a car lot. I think any Japanese car that came in contact with it would look like a crumpled soda can since its made of steel. Gas hog? Of course thats the American way! We should not have to model our lives after mamby-pamby girly boys.  :D
Title: Re: Modern tank cannons - smooth vs rifled
Post by: FrodeMk3 on August 21, 2008, 11:23:01 AM
Unless you are firing Sabot rounds, then the smooth bore will be more accurate.  The fins on Sabot rounds stabilize the round in flight so the rifling isn't needed, or wanted even.

The rifling imparts a spin to the projectile which stabilizes it in flight and makes it more accurate.

If you fellas are really interested in AFV Main Gun and armor comparisons, check this out:http://members.tripod.com/collinsj/protect.htm (http://members.tripod.com/collinsj/protect.htm)

It's pretty up to date, and it has some interesting Data.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Cthulhu on August 21, 2008, 11:24:52 AM
Unless you are firing Sabot rounds, then the smooth bore will be more accurate.  The fins on Sabot rounds stabilize the round in flight so the rifling isn't needed, or wanted even.

The rifling imparts a spin to the projectile which stabilizes it in flight and makes it more accurate.
Another VERY important reason why modern MBTs don't use rifled barrels is that the preferred weapon to kill other tanks is what's called a "long-rod penetrator". These weapons, like the Abram's "Silver Bullet", have large L/D values (long and narrow) which concentrate a lot of energy over a very small area. (sectional density to you guys who shoot or reload). These long darts can't be spin-stabilized worth a damn because they wobble badly if spun at high rpm's. They have to be fin-stabilized and encased in sabots.

In addition, HEAT rounds really don't like being spun either, the rotation having a negative effect on the forming of the copper slug and the blast shape. The French found this out with their old AMX-30 and actually mounted the hollow charge on bearings within their HEAT rounds to minimize spin.
 
These are probably the main reasons that smooth-bores are used. Although less barrel wear is definitely a plus.


Oh, and Clarkson is always taking shots at Americans. I just laugh it off. Top Gear is great. :aok
Title: Re: Modern tank cannons - smooth vs rifled
Post by: FrodeMk3 on August 21, 2008, 01:22:49 PM
See my above post. 120MM gun not 122mm.

Also the Soviets last tank that had a rifled barrel was the T-54/55. That had a 100mm rifled main gun. The T-64/72/80/90 ALL use a 125mm smooth bore main gun, the T-62 used a 115mm smooth bore main gun, so I don't know what tanks they had that they were carrying extra barrels into battle. Also changing the main gun tube on a tank is NOT something the crew can do on their own, and is NOT something you stop and do in the middle of a battle. Also the most commonly used tank by the Soviets in Afghanistan was the T-64. The Soviets supplied old T-55's to Afghan Army units. Desert Storm the Iraqi's were using T-62's T-72's for the most part. Some units were equipped with the old T-55's, but I never saw an Iraqi tank with a spare barrel strapped on the side and I saw ALOT of blown up tanks over there.

Hornet, the T-64, even with it's long service life, has only ever seen combat in Chechnya. The Primary tank used in Afghanistan was the T-62.

Quote
During the Soviet war in Afghanistan, the T-62 was a primary tank used by the Soviet army.[16] The Soviets used tanks pretty much in the same way as the US Army did in Vietnam, with many tanks in fire support bases. Towards the end of the war T-62Ms appeared in large numbers. This modernized variant of T-62 had the BDD appliqué armour package specially designed to defeat shaped charges (for example RPGs). Many T-62s fell victim to Mujahideen attacks and, especially, antitank landmines, as did many Soviet AFVs sent there. Many also fell into the hands of the Afghan Mujahideen after being left behind by withdrawing Soviet forces. Those vehicles as well as derelict ones restored to working order are now used Afghan National Army. Afghan army operates 170 T-62, T-62M and T-62M1 tanks.[11]

The Russian army has also used both T-62s and T-62Ms in combat in Chechnya. The T-62M is still being used for counterterrorism operations in this region.[12]

http://en.wikipedia.org/wiki/T-62 (http://en.wikipedia.org/wiki/T-62)
Title: Re: Modern tank cannons - smooth vs rifled
Post by: indy007 on August 21, 2008, 05:05:45 PM
That is not an M1, and the T's of any brand had a bad day against the Challenger.
But....is it the weapon, or is it the man behind it?

I think it's obvious, the tank is not the asset at all, the crew is. You can build a new tank far faster than you can re-train a good crew. Pretty much all MBTs have the same basic features... Challenger, Leopard 2A6, M1A2, Merkava 4, T-90... long gun, heavy armor, high speed, good optics & sensors, good comms. Now except for the T-90, which I don't think has seen combat yet, does anybody know of a case of any of these tanks ever losing crew members? I know some M1s and Merkavas have been disabled, but I haven't read of any crew losses. I do remember one story of a M1 driver having his tank wrecked with a multiple 105mm shell IED, but they carved into the tank 6 hours later and the guy was still in his position without a scratch, just really bored.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: FrodeMk3 on August 21, 2008, 05:13:51 PM
I think it's obvious, the tank is not the asset at all, the crew is. You can build a new tank far faster than you can re-train a good crew. Pretty much all MBTs have the same basic features... Challenger, Leopard 2A6, M1A2, Merkava 4, T-90... long gun, heavy armor, high speed, good optics & sensors, good comms. Now except for the T-90, which I don't think has seen combat yet, does anybody know of a case of any of these tanks ever losing crew members? I know some M1s and Merkavas have been disabled, but I haven't read of any crew losses. I do remember one story of a M1 driver having his tank wrecked with a multiple 105mm shell IED, but they carved into the tank 6 hours later and the guy was still in his position without a scratch, just really bored.

(Quoted for truthfulness)

If you consider the way the Iraqi's employed their Tanks' in GW1 and II, you'll see that tactics, training, and intelligence have a lot to do with it too. You can't just drive out onto the modern battlefield in a tank, and expect to get within sight of the enemy and be invulnerable. Nobody's built an AFV yet that can do that.  The Iraqi's dug their tanks' in, but in bare open sand (at least, that's what a lot of GW I pics' show) and although the hulls' were protected, the turrets' were exposed, due to a lack of any other kind of cover. They just died in their revetments, for the most part sitting ducks.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Elfie on August 21, 2008, 06:16:22 PM
Quote
Another VERY important reason why modern MBTs don't use rifled barrels is that the preferred weapon to kill other tanks is what's called a "long-rod penetrator".

Also, you can't fire missiles from a rifled bore. Although I'm not sure if any tanks do this anymore. I know the M-60 could fire a missile down it's 105 tube, but I forget what it was called now.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: FrodeMk3 on August 21, 2008, 06:46:28 PM
Also, you can't fire missiles from a rifled bore. Although I'm not sure if any tanks do this anymore. I know the M-60 could fire a missile down it's 105 tube, but I forget what it was called now.

Most of the T-series' russian tanks armed with the 125mm can fire either the AT-8 or AT-11's.http://en.wikipedia.org/wiki/AT-11_Sniper (http://en.wikipedia.org/wiki/AT-11_Sniper)

Title: Re: Modern tank cannons - smooth vs rifled
Post by: Maverick on August 21, 2008, 11:17:21 PM
Also, you can't fire missiles from a rifled bore. Although I'm not sure if any tanks do this anymore. I know the M-60 could fire a missile down it's 105 tube, but I forget what it was called now.

M60's didn't have a missile, you're thinking about the Sheridan Tank and the shillelagh (SP??) missile. The guidance computer for the missile didn't like the cannon. Firing a cannon round (155mm) would scramble the missile system.
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Elfie on August 22, 2008, 12:10:44 AM
Quote
you're thinking about the Sheridan Tank and the shillelagh (SP??) missile.


Yeah thats it. :)
Title: Re: Modern tank cannons - smooth vs rifled
Post by: FrodeMk3 on August 22, 2008, 12:17:18 AM
M60's didn't have a missile, you're thinking about the Sheridan Tank and the shillelagh (SP??) missile. The guidance computer for the missile didn't like the cannon. Firing a cannon round (155mm) would scramble the missile system.

Perhaps' the M-60A2? (http://upload.wikimedia.org/wikipedia/commons/5/59/M60A2-drives-off-LARC-60-198510513-2.JPG)

Quote
M60A2 'Starship'
 
M60A2 tank is driven off LARC 60 amphibious landing craft during the Army exposition PROLOG '85.The M60A2, nicknamed the "Starship" due to its space-aged technology, featured an entirely new low-profile turret with a commander's machine-gun cupola on top, giving the commander a good view and field of fire while under armor but spoiling the low profile. It also featured a 152mm caliber main gun similar to that of the M551 Sheridan light tank, which fired regular rounds as well as the Shillelagh anti-tank guided missile (ATGM). The fitting of a CBSS (closed breech scavenger system) which used pressurized air used to clear the breech after each shot solved some problems such as unburnt propellant from the main gun rounds fouling the barrel and pre-detonating subsequent rounds. The M60A2 proved a disappointment, though technical advancements would pave the way for future tanks. The Shillelagh/M60A2 system was phased out from active units by 1981, and the turrets scrapped. Most of the M60A2 tanks were rebuilt as M60A3, or the hulls converted to armoured vehicle-launched bridge (AVLB) vehicles.[1]
Title: Re: Modern tank cannons - smooth vs rifled
Post by: Cthulhu on August 22, 2008, 01:42:21 AM
M60's didn't have a missile, you're thinking about the Sheridan Tank and the shillelagh (SP??) missile. The guidance computer for the missile didn't like the cannon. Firing a cannon round (155mm) would scramble the missile system.
Shillelagh was also intended for the old MBT-70. (still looks cool after all these years)
Included an autoloader and a remote-controlled 20mm for anti-aircraft use. Driver sat in the turret.

(http://upload.wikimedia.org/wikipedia/commons/f/fe/MBT-70.Aberdeen.0007rb5r.jpg)