Viability of Modernizing old Tanks?

[Sarevok]

I think Skimmer is referring to the thin armor on the BMP-3. The Bradley is a considerably heavier and better armored as a consquence.

[Norade]

Yeah, I just wonder how bad the Bradley is compared to the BMP-3. Though it sounds like the BMP must lose by a significant percentage even though it seems to be the better armed tank. Fire control and C3 will obviously go to the Bradley though, as does survivability.

[Marcus Aurelius]

The new gun does have a significantly higher rate of fire than the original 76 mm gun, which can be useful for supporting infantry.

Yeah I think that's the idea. Use the 57mm to suppress bunkers, buildings and troops in the open as well as light-medium while you are making an amphibious landing. Tanks on the beach are priority targets for naval gunfire and attack helicopters. Once they have a beachhead they can bring ashore a lot of ATGMs and T-55s to cope with enemy armor. On land the 57mm should deal with Stryker class deathtraps efficiently even with its 1950s AP ammo. A lot of medium armor has serious protection against 30mm cannon fire these days but that's still nowhere near 57mm energy levels.

I still wonder, though, if the 57 mm autocannon makes much sense in the final analysis. The 76 mm gun had a much more useful size HE shells, so I don't think there should be that much difference in suppressive capability. As for fighting against light armor, they could have designed a modern HEAT shell for the 76 mm, which should be able to penetrate something like 400 mm of RHA quite easily. Even the old BK-350M HEAT was rated for 280 mm penetration and it was 1960s tech, if I remember correctly. Modern HEAT should have in the ballpark of 30%-50% higher penetration.

About the only situation where the 57 mm autocannon would be significantly superior than the 76 mm with modern ammunition is engaging helicopters or shooting at moving ground targets at long ranges, where the higher muzzle velocity is a big advantage. That said, I remember reading that they actually used old S-60 barrels from guns that had seen barely any use, so perhaps the 57 mm option was simply cheaper than designing new ammunition for the 76 mm gun.

[Sea Skimmer]

I think Skimmer is referring to the thin armor on the BMP-3. The Bradley is a considerably heavier and better armored as a consquence.

I think Skimmer is referring to the thin armor on the BMP-3. The Bradley is a considerably heavier and better armored as a consquence.

Not so much the thin armor even; the BMP-3 can take heavy appliqué armor like the Bradley can to gain worthwhile protection.
http://www.allempires.net/uploads/20060 ... rmor-0.jpg

The Russian Army does not field it this way at the moment; but that’s because they want the vehicle to stay amphibious. The main issue is a BMP-3 has 40 rounds of 100mm shells and cartridges and anti tank missile warheads and rocket motors in an exposed autoloader. Wrapped inside and around that is 500 rounds of exposed 30mm and several thousand machine gun rounds, plus whatever ammunition the rifle squad in the back might be carrying. To make life even more fun, the 100mm ammo stands upright so it has the largest possible target profile for an incoming hit. How the hell is the thing not supposed to be catastrophically obliterated along with everyone inside by anything that hits it?

The auto cannon ammunition is actually more vulnerable to ignition then the 100mm rounds, but it takes many 25-30mm shells burning to cause an explosion, the crew should have time to escape. One 100mm round going off is very bad, and one missile going off is also very bad. The make things worse the BMP-3 uses an unusual opposed piston engine which is placed at the rear of the hull, with the infantry exiting over the top. That means an engine fire can easily cut off the main means of crew escape.
http://yd1hdt.files.wordpress.com/2008/11/bmp-3cut1.jpg

A front engine, found on well, a crapload of IFVs, makes a lot more sense because the engine block provides a fair bit of protection to the crew. Engine fires will destroy vehicles, but usually not quickly. It seems the FCS program though actually had the engine on the fucking middle of the side… with hybrid batteries on the opposite side as ballast.

Anyway, on the Bradley they recognized the ammo storage - fireball problems and made changes on A2 models and later. A lot of reserve ammunition storage was moved to external bins in-between the appliqué armor and the hull, the ammo now actually acts as more armor. Flammable armor, but armor none the less. The ready ammo in the turret is wrapped in a spall liner with a wide standoff from the hull exterior.

By definition an infantry fighting vehicle is a highly offensive type of design, you can’t really ever expect one of them to survive very well unless it weighs more then 50 tons, but you can expect a well designed vehicle to hold together a little while before burning and exploding, at least long enough for the surviving infantry squad and crew to get the wounded out and continue to fight.

The Soviets just didn’t think like that in terms of individual unit survivability; it wasn’t possible with amphibious designs since the armor was stuck being almost paper thin. They believed in survivability through total suppression of the anti tank defense using every possible weapon. The 100mm gun allows the BMP-3 to extend suppression much more deeply into the enemy position; its 7,000 meters which matches virtually all anti tank missiles range and comfortably exceeds that of might TOW and HOT which armed compromised majority of NATO heavy ground based anti tank missile launchers. 25-30mm can optimsitcally be effective at 3,000-4,000 meters, this isn’t enough to engage the missiles before they can engage the BMP.

This idea does not work so well in smaller actions in the modern age, when forces are smaller, more dispersed and more likely to rely on indirect fires whenever possible. Mass firepower only works if you have well, mass. Individual unit superiority, of which survivability is a major factor, counts for proportionally more and more because you simply cannot blanket the entire landscape in firepower. The enemy is going to get a chance to hit you.

I think the BMP-3 is really neat; it would make a great deal sense for a 1989 Soviet motor rifle division to have one regiment of them, plus a BMP-2 and BTR-80 regiment (almost nothing had all three regiments with BMPs). But I really wouldn’t want to have a modern force equipped with the things unless it was reuse of the turret on a light tank hull of my choice; this option does exist for sale.

[Coyote]

The new gun does have a significantly higher rate of fire than the original 76 mm gun, which can be useful for supporting infantry.

Yeah I think that's the idea. Use the 57mm to suppress bunkers, buildings and troops in the open as well as light-medium while you are making an amphibious landing.

I still wonder, though, if the 57 mm autocannon makes much sense in the final analysis. ...

About the only situation where the 57 mm autocannon would be significantly superior than the 76 mm with modern ammunition is engaging helicopters or shooting at moving ground targets at long ranges, where the higher muzzle velocity is a big advantage...

If an autocannon is what you want, it might be better to purpose-build a new light tank to specifications. An old MBT has a decent recoil-absorbing chassis which is overbuilt for little autocannons; maybe use that chassis to upgrade to a heavier standard gun like a 120mm but mount it, assault-gun style, in a casemate with limited traverse to use against fortifications and infantry support. The advantages being that a casemate-housed assault gun will have a lower profile and do away with all the complexities of a turret, which is a bonus for armies trying to stretch a buck.

[Zaune]

Not sure how you'd cram a 120mm gun with a useful ammunition load and the bottom end of a powered turret into a hull that would be much use in an urban environment; you'd end up with either several metres of barrel sticking out the front or something considerably longer and wider than anything currently in use, both of which would cause major problems with handling. Something like the 60mm mortar fitted to the Merkava might be a better bet; I can't remember off-hand if HESH or similar mortar rounds already exist, but they should be feasible.

[CaptHawkeye]

BMP-3 etc

I guess that's just what the Russians get for trying to cram so much firepower into a very tiny package. I don't suppose they could cut back on extra ammunition stowage? It probably wouldn't do much.

[erik_t]

Not sure how you'd cram a 120mm gun with a useful ammunition load and the bottom end of a powered turret into a hull that would be much use in an urban environment; you'd end up with either several metres of barrel sticking out the front or something considerably longer and wider than anything currently in use, both of which would cause major problems with handling. Something like the 60mm mortar fitted to the Merkava might be a better bet; I can't remember off-hand if HESH or similar mortar rounds already exist, but they should be feasible.

For whacking bunkers, one does not need a terribly high-velocity gun.

[Simon_Jester]

Not sure how you'd cram a 120mm gun with a useful ammunition load and the bottom end of a powered turret into a hull that would be much use in an urban environment; you'd end up with either several metres of barrel sticking out the front or something considerably longer and wider than anything currently in use, both of which would cause major problems with handling. Something like the 60mm mortar fitted to the Merkava might be a better bet; I can't remember off-hand if HESH or similar mortar rounds already exist, but they should be feasible.

I think Coyote's proposing to dispense with the turret entirely for the 120mm-armed variant, turning it ino something more like a StuG. Or am I misunderstanding?

[Zaune]

You may be right; I understood him to be talking about putting an auto-cannon turret on top of a StuG.

Mind you, didn't Sweden try something like this a while back, only to decide that StuGs went out of fashion for a reason and buy Leopard IIs instead?

[Simon_Jester]

The S-tank. Basically, invented as a dedicated defensive vehicle to engage advancing Soviet mechanized forces by finding hull-down ambush positions, because nothing got more hull-down than an S-tank.

Never saw combat, but for all I know it might have worked; in any case, this hypothetical assault gun would probably look a lot like the S-tank, but not exactly the same. And the concept for its use would be different.

[Shroom Man 777]

The S-tank was said to be able to fire just as accurately, if not more so, than its contemporary MBTs. I wonder how well it stacks up to more modern designs and systems.

[Simon_Jester]

Well, accurate gunnery was important for its role as a long range ambush-tank. The idea was that it could find a nice spot to hunker down and get into a long range gun duel with Soviet armor, where its lower target profile and accurate sights would be an advantage. Then after enough time had passed, it would kick into reverse gear and get the hell out of there.

At short range the S-tank would be at a tremendous disadvantage because of its fixed mount gun, so it makes sense that they'd optimize the tank for accurate long range gunnery. The problem is that there's more to a good tank design than that: the S-tank's inability to fire on the move could become a problem, for instance. The main argument for an assault gun designed along the same lines as the S-tank would just be cost, not so much "we get better performance this way." It's a cheap way to mount the heaviest-caliber guns onto a small chassis.

[Coyote]

Yeah, I was talking turretless, like a STuG. A more contemporary example (well, 1980's contemporary) would be like the ASU-85 airborne assault gun the Soviet Airborne had... but that is only an example of the concept; the ASU-85 was, IIRC, a PT-76 light tank chassis with a 76mm gun on it.

But you can take a T-55 or T-62 chassis, dispense with the turret entirely and put a heavier gun on it like a 105mm or 120mm and use it assault-gun style. You might get only 15 degrees of traverse at best, but it is still better than nothing and it can be useful in certain roles. An assault gun has to work primarily as a infantry support weapon and in close coordination with dismounts, it'd be meat on the table in open tank country.

As the Germans found out, in a tank-sparse army some assault guns can be a good stopgap measure in a pinch, and they can do well if they are well-hidden and camouflaged in a defense, but you wouldn't want to rely on them as tank replacements. A poor army in, say, the former Soviet republics or Africa might do well to convert some of their old T-55s and such into assault guns, while scrapping the rest and getting T-72s, and then being careful in how they are combined and used. Likely they aren't going to be going up against a lot of tank armies anyway, or organized AT defenses, since a lot of the countries still using T-55s tend to use their armies as Gendarmeries for internal "security" more than actual combat forces-- which is why T-55s have managed to remain relevant for so long in some of those countries: they're more than enough against peasants and the occasional radical group.

A good T-72 modernization was when old-school Yugoslavia hired the Israelis to upgrade the export versions of the T-72 that the Soviets had given them. Upgraded fire controls, laser rangefinders, cant sensors, etc, turned the T-72s into the M-84 which was still a pretty capable tank.

[Pelranius]

The M84 also had a machine gun and sensors that detect ATGM launches, determine the direction the missile was coming in from and would automatically fire in the direction of said ATGM crew (back when a lot of missiles had to be wire guided to the target). Always thought that a pretty nifty feature.

[[R_H]]

But you can take a T-55 or T-62 chassis, dispense with the turret entirely and put a heavier gun on it like a 105mm or 120mm and use it assault-gun style. You might get only 15 degrees of traverse at best, but it is still better than nothing and it can be useful in certain roles.

Wouldn't that require increasing the height of the hull? What about building a new turret (AC- and RPG(-7)-resistant)?


BAE Systems has a concept vehicle similar to what you're proposing, the CHARGER.

described as a "highly specialized lethal effects vehicle", the CHARGER is a cross between a tank and a bulldozer. Apart from it's ability to punch through walls, the 30 tonne vehicle could be equipped with vertical launched missiles, mortars and/or cannon depending on the target. It would also employ actuated spaced armor options designed to create space between the vehicle and it's shield. This could include using electro-magnetic magnets that could be deployed to "float" above a vehicle in a threatening situation.

[Zaune]

When did BAE start headhunting concept artists from Games Workshop?

[Pelranius]

Looks like the UK caught FCS fever after us and the Chinese (both of which have since dropped the projects and gone on to heavier programs). Though admittedly the BAE system is a lot less complicated, so it shouldn't be too hard to pull off, mechanical sweat aside.

[The Dark]

Yeah, I was talking turretless, like a STuG. A more contemporary example (well, 1980's contemporary) would be like the ASU-85 airborne assault gun the Soviet Airborne had... but that is only an example of the concept; the ASU-85 was, IIRC, a PT-76 light tank chassis with a 76mm gun on it.

PT-76 chassis with an 85mm M-44 gun (the same as the T-34/85). According to Isby's Weapons and Tactics of the Soviet Army, the optics were similar to those on the T-62.

[[R_H]]

Looks like the UK caught FCS fever after us and the Chinese (both of which have since dropped the projects and gone on to heavier programs). Though admittedly the BAE system is a lot less complicated, so it shouldn't be too hard to pull off, mechanical sweat aside.

Some of the stuff sounds like it would be really complicated to get working, like power in structure, or pores in armour to sweat water through.

[Marcus Aurelius]

Well, accurate gunnery was important for its role as a long range ambush-tank. The idea was that it could find a nice spot to hunker down and get into a long range gun duel with Soviet armor, where its lower target profile and accurate sights would be an advantage. Then after enough time had passed, it would kick into reverse gear and get the hell out of there.

At short range the S-tank would be at a tremendous disadvantage because of its fixed mount gun, so it makes sense that they'd optimize the tank for accurate long range gunnery. The problem is that there's more to a good tank design than that: the S-tank's inability to fire on the move could become a problem, for instance. The main argument for an assault gun designed along the same lines as the S-tank would just be cost, not so much "we get better performance this way." It's a cheap way to mount the heaviest-caliber guns onto a small chassis.

I suppose you haven't been to Sweden ever? Because there is not many places where long range gunnery would be useful. The typical line-of-sight is probably less than 1,000 meters. Skåne (southermost Sweden) is about the only place where it's significantly more, but I can tell you that the Swedes did not design their tank exclusively that in mind, since it was not a likely invasion area for the Soviets.

We have to remember that the S-tank was designed in the early 1960s. Back in those days tanks didn't really have fire on the move capability. The job of the gun stabilization, which was not even universally available in all tanks at the time, was to make target acquisition faster during the stop required for accurate firing. No tankers were taught to engage armored targets on the move back then (soft targets were a different matter, since pinpoint accuracy was not always required for suppressive effect with HE shells).

The S-tank was also specifically designed with a short hull so that it could make very fast 90 degree turns. In Swedish tests it was able to match the turret traverse rate of the Centurion while stationary and exceed it while on the move. The S-tanks crews performed very well in mock combat against the Centurions, which was the most modern comparison platform available to the Swedes. Before the S-tanks were finally retired they also tested them in combat exercises against the Leopard 2s and they performed quite well in all tactical situations (i.e. not only in defense), although they did admit that at that point the Leopard 2 crews were less experienced with their vehicles than the S-tank crews.

The idea of the S-tank was not so much to have a heaviest possible gun, but the have the lowest possible profile combined with a very good frontal armor. When the S-tank was introduced it had the best frontal armor of any medium tank. The Chieftain had slightly better frontal armor but it was a much heavier vehicle. Of course that class leadership was relatively short lived with the introduction of the T-64, but nevertheless it was pretty good. Also, unlike the T-64's frontal armor, the S-tank's armor provided a uniform protection with virtually no weak spots. For example the Soviet 100 mm and 115 mm guns tank could not penetrate the S-tank's frontal armor until the 1980s, which was an achievement only the Chieftain could share until the introduction of the Leopard 2 and M1 Abrams. Even the 1960s vintage 125 mm APFSDS would have been hard pressed to penetrate except at very close ranges.

[Fingolfin_Noldor]

Sweden is a pretty mountainous and forested country, with many areas rather narrow for tanks. The place could be adequately defended on land with a relatively small army. As such, a tank like the S-tank could hide very easily and set off pretty decent ambushes if given modern ammunition.

[Simon_Jester]

I suppose you haven't been to Sweden ever?

No, in point of fact, I have not. I was thinking of the S-tank in terms of the Abstract Defensive Tank. For which I would think accurate long range gunnery would be a logical priority, because it complements the tank's low target profile when dug in.

I was not thinking of the S-tank as the Terrain Specific Defensive Tank because I am not qualified to comment on the terrain of Sweden because, as you point out, I am not Scandinavian. If I had gone off and claimed that long range gunnery was useless for the tank because of short sight ranges... there would be no reason for me not to expect someone like you to jump in and say "hah, shows what you know, if you pick your spots you can have lines of sight out to X thousand meters easily!"

So I chose to make no assumptions about the terrain the Swedes expected the S-tank to fight in, rather than making a specific assumption I had no justification for.

Sweden is a pretty mountainous and forested country, with many areas rather narrow for tanks. The place could be adequately defended on land with a relatively small army. As such, a tank like the S-tank could hide very easily and set off pretty decent ambushes if given modern ammunition.

My impression was that the tank was designed with this in mind. I had assumed that its good gun accuracy (noted by others) was a feature designed to complement its ability to fight as a long range "tank sniper," because I did not factor in the terrain.

Factoring in the terrain I don't know why they bothered to work hard on gun accuracy, which I infer they must have done because they wound up with a tank that could shoot more accurately than most of its competitors. Maybe I'm off base, they didn't have to work hard on accuracy, and got it anyway as a happy accident rather than as a major design goal.

[Sea Skimmer]

Yeah, I was talking turretless, like a STuG. A more contemporary example (well, 1980's contemporary) would be like the ASU-85 airborne assault gun the Soviet Airborne had... but that is only an example of the concept; the ASU-85 was, IIRC, a PT-76 light tank chassis with a 76mm gun on it.

ASU-85 is a PT-76 with a 85mm gun. However a couple enclosed turret 85mm versions of PT-76 were designed, though only produced as sub variants in China and North Korea. The same 85mm gun also mounted on a BTR-70 but that was also not mass produced by the USSR. My understanding of the ASU-85 is that it had no turret in ordered to have a very low profile to fit in smaller aircraft and under choppers.

But you can take a T-55 or T-62 chassis, dispense with the turret entirely and put a heavier gun on it like a 105mm or 120mm and use it assault-gun style. You might get only 15 degrees of traverse at best, but it is still better than nothing and it can be useful in certain roles. An assault gun has to work primarily as a infantry support weapon and in close coordination with dismounts, it'd be meat on the table in open tank country.

Something the size of a T-55 can take a 122mm howitzer in a fully rotating turret, IIRC Egypt has such design in service. The armor won't be that heavy but it really beats being limited arc. A fixed gun means throwing a track, say after you hit a mine or take artillery damage will cripple your main firepower.

As the Germans found out, in a tank-sparse army some assault guns can be a good stopgap measure in a pinch, and they can do well if they are well-hidden and camouflaged in a defense, but you wouldn't want to rely on them as tank replacements. A poor army in, say, the former Soviet republics or Africa might do well to convert some of their old T-55s and such into assault guns, while scrapping the rest and getting T-72s, and then being careful in how they are combined and used. Likely they aren't going to be going up against a lot of tank armies anyway, or organized AT defenses, since a lot of the countries still using T-55s tend to use their armies as Gendarmeries for internal "security" more than actual combat forces-- which is why T-55s have managed to remain relevant for so long in some of those countries: they're more than enough against peasants and the occasional radical

The Germans didn't face tanks that could fire on the move, at this point those can show up anywhere in the world. That really makes a fixed gun a non starter.

This is also the reason why the S-tank was not followed up as mentioned above. It has some very clever twin engine and transmission steering controls to make it just as easy to aim as turning a turret, in the 1960s. At the time all threat tanks still had to stop to fire and most had no active means of rangefinding. But modern tanks can fire on the move with accuracy and can traverse turrets 360 degrees in as little as 6-9 seconds vs. 20-30 seconds for a T-62 of the era. That's a very big difference.

Plus anti tank missiles work so well now, that solves a lot of your low profile problems out of hand against armored attack. Turrets are cheap enough now that its just kind of silly not to have one unless you are mounting an indirect fire piece.

A good T-72 modernization was when old-school Yugoslavia hired the Israelis to upgrade the export versions eof the T-72 that the Soviets had given them. Upgraded fire controls, laser rangefinders, sensors, etc, turned the T-72s into the M-84 which was still a pretty capable tank.

Yeah a upgraded T-72 can meet most tank needs, pretty much forever. Its far more credible then a T-55 and better even for a mobile artillery role blowing up buildings.

[Marcus Aurelius]

I was not thinking of the S-tank as the Terrain Specific Defensive Tank because I am not qualified to comment on the terrain of Sweden because, as you point out, I am not Scandinavian. If I had gone off and claimed that long range gunnery was useless for the tank because of short sight ranges... there would be no reason for me not to expect someone like you to jump in and say "hah, shows what you know, if you pick your spots you can have lines of sight out to X thousand meters easily!"

My impression was that the tank was designed with this in mind. I had assumed that its good gun accuracy (noted by others) was a feature designed to complement its ability to fight as a long range "tank sniper," because I did not factor in the terrain.

Factoring in the terrain I don't know why they bothered to work hard on gun accuracy, which I infer they must have done because they wound up with a tank that could shoot more accurately than most of its competitors. Maybe I'm off base, they didn't have to work hard on accuracy, and got it anyway as a happy accident rather than as a major design goal.

Sure, even in Sweden you can find places where 2000+ meters firing ranges can be achieved, but the problem with them is that they are not very common and a capable commander of the attacking force would anticipate long range AT defenses at such points, and allocate artillery and possibly air assets to suppress the defenses. Often the best defensive position is also the most obvious, which means that sometimes the second or third best position is actually the best.

The S-tank did have fairly good FCS for its time and the gun barrel is significantly longer than the standard NATO 105 mm L7/M68 rifled tank gun (L/62 instead of L/52). Therefore it was one of the most effective 105 mm guns until the Americans and French designed DU penetrators for their 105 mm guns, which the Swedes of course could not utilize due to political reasons, although I have heard rumors that in the 1980s some Swedish generals were trying to get such rounds accepted. So long range anti-tank sniping was certainly possible with the S-tank, but it was not designed exclusively or even primarily with that in mind.

EDIT: fixed the quotes.