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I am fully aware that you can put fuel tanks there, my point was that it's a big empty space that is excellent for ammunition storage.

 

I see your point, although I still don't know about a place where "if you get penetrated, your ammo goes up" being an excellent location for that.

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I see your point, although I still don't know about a place where "if you get penetrated, your ammo goes up" being an excellent location for that.

It is as excellent as the Challenger II's ammunition storage. 

 

Space efficient but very deadly for the crew.

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Actually, as a ex-Leo 2A6 crew member and current TNO researcher told me, he thinks it's the biggest flaw of the Leo 2 design. He also went as far as claim that the lower plate isn't actually all that thick. Which, combined with the ammo stowage behind the lower plate makes me raise an eyebrow.

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Actually, as a ex-Leo 2A6 crew member and current TNO researcher told me, he thinks it's the biggest flaw of the Leo 2 design. He also went as far as claim that the lower plate isn't actually all that thick. Which, combined with the ammo stowage behind the lower plate makes me raise an eyebrow.

One thing I have been pondering about lately is:

It is possible to extend the ammunition rack to the whole width of the bustle?

Removing the pumps and old FCS should clear up space. Alternative you could add a auto loader like the Leclercs if you need it for the 130mm gun. 

 

So you can either:

Install a autoloader.

Increase ammunition capacity.

Or move more ammunition to the turret.

 

Would this be too expensive? 

 

The hull rack could be made into a armored wet storage rack, with fuel tanks on the side for added protection. But I have a feeling they would simply leave it as it is for increased ammunition capacity.

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Actually, as a ex-Leo 2A6 crew member and current TNO researcher told me, he thinks it's the biggest flaw of the Leo 2 design. He also went as far as claim that the lower plate isn't actually all that thick. Which, combined with the ammo stowage behind the lower plate makes me raise an eyebrow.

That sounds like a hell of a liability in dealing with IEDs

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That sounds like a hell of a liability in dealing with IEDs

 

It would take a really big or specialized mine.  Those do exist, but the 20-40mm of belly armor most MBTs have makes them a hell of a lot harder to kill with mines than, say, trucks or APCs.  To put it in perspective, most MBTs have about two to three times as much belly armor as a LAV-25 has over the frontal arc.

 

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   IEDs are not really a problem for LFP. Generally only EFP mines can be real danger, but they are usually placed in such way that only side armor is in real danger.

 

   And ALL Western tanks are needlessly big comapred to MUH SOVIET MEDIUM TANKS like T-64. Yes, medium, because i am now fully into "USSR never had MBT from 1960s to 1990s" theory.

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One thing I have been pondering about lately is:

It is possible to extend the ammunition rack to the whole width of the bustle?

Removing the pumps and old FCS should clear up space. Alternative you could add a auto loader like the Leclercs if you need it for the 130mm gun. 

 

So you can either:

Install a autoloader.

Increase ammunition capacity.

Or move more ammunition to the turret.

 

Would this be too expensive? 

 

The hull rack could be made into a armored wet storage rack, with fuel tanks on the side for added protection. But I have a feeling they would simply leave it as it is for increased ammunition capacity.

 

For the record, I'm dubious about the effectiveness of wet ammo stowage.  Sure, wet ammo rack Shermans burned far less frequently than their dry rack counterparts.  Wet rack Shermans also moved the ammo out of the easily-penetrated hull sponsons and onto the hull floor, where they were less likely to get hit in the first place. 

The chemistry just doesn't make much sense.  Gun ammunition and explosives contain both fuel and oxidizer, so pouring water over burning nitrocellulose won't snuff it out like it would a regular fire.  In a few edge cases, if the water gets to the spark very early the heat energy could dissipate into the water quickly enough that the temperature inside the propellant would drop, and the combustion could no longer proceed.  Maybe maybe maybe the water could get into a hole fast enough to waterlog the propellant, which would render it more or less inert, but flame propagation in nitrocellulose-based propellants is scary fast and I would be shocked if water managed to outrun it.  I would think in most cases, however, that the wet ammo stowage just slows down the fire by absorbing some of its energy for a time.  This is not without value, as it could allow precious extra seconds for the crew to GTFO.

 

I recall some study of knocked-out tanks from the Iran-Iraq War, including T-62s and Chieftains, which concluded that the wet ammo stowage on Chieftains did not make them less prone to fire.

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Does anyone have ground clearance figures for the T-72?  I had always heard that it's about two inches less than for Western MBTs.

According to Steven Zaloga, the T-72 has 490 mm ground clearance; this about the same as the M1 Abrams (19 inches/482 mm according to Hunnicutt), but about two inches less than the frontal area of the Leopard 2 (550 mm).

 

Also curious if anyone has figures showing the approximate thickness of the armor in the front hull of the Leo 2.

The upper section of the Leopard 2's hull nose (the one sloped at ~45°) has a line-of-sight thickness of more than 600 milimetres. The distance to the end of the special armor cavity is 600 mm, behind this is a further steel plate; I have commonly seen estimations in the range of 640-660 mm.

This is essentially the same thickness as the armor cavity with backplate on the Abrams (estimated to be 600-700 mm). Also one should note that this is the same thickness as the M1A1 Abrams and Leopard 2A4 turret when attacked from 30° angle.

The composite armor at the lower nose section gets thinner; to some 200-300 mm-ish thickness until it ends. Something like this photo from SteelBeasts shows, but the lower armor cavity slopes back and is no straight.

 

56e83cf99636b_leopard_2a5hullarmor.jpg.5

Overall it appears that the Leopard 2 has essentially the same armor thickness at the hull front as the M1 Abrams. The full thickness of the armor cavity might cover a slightly smaller area, but overall the Leopard 2 seems to have a slightly larger coverage of the front hull with composite armor.,

 

However the Leopard 2 has further armor packages for the hull available, such as IBD's MEXAS-H design (as adopted on Strv 122, Leopardo 2E, Leopard 2HEL, Leopard 2A5DK and Leopard 2A7 QAT), RUAG's SidePro armor aswell as the AMAP armor (as operational with Singapore and Indonesia). This armor packages add at least one foot thickness of composite armor to the tank. When the adoption of this armor package was tested on the M1A2 and Leclerc tanks for Sweden, the Swedish FMV noted a 50-100% increase in protection according to FMV's Richard Lindström.

 

strv_ny-16.jpg

 

In Germany the armor package was originally ordered in 1995 for adoption within the KWS 3 upgrade (whole hull would require an overhaul for KWS 3, as this meant the adoption of a new turret with 140 mm gun), but the order was canceled shortly after. Currently Germany is trying to enhance the Leopard 2A7 design (enhanced tank currently codenamed Leopard 2A7V), which also includes the adoption of the further armor package.

 

Frontal hull vulnerability, at first glance, looks like one area where the Abrams is greatly superior to the Leo 2.  The left side of the Leo 2 hull is filled up with non-compartmentalized ammo and the right side of the Leo 2 hull is filled up with driver.  On the Abrams the driver is centerline, and the right and left are filled with fuel tanks.

 

If you are talking about crew survivability, the frontal fuel tanks of the Abrams might be an advantage. On the other hand, once the fuel tanks are hit and the fuel is incinerated, the tank has be abandoned unless you want to eat fried Abrams tankers.

The fuel tanks of the Abrams are more likely to be incinerated, because of the thinner side armor compared to the Leopard 2. The Leclerc might have the best hull armor design (at least as long as there is no AMAP/MEXAS-H armor), but it's lower front is not protected by composite armor.

 

I always thought it was an odd decision to put the ammo at the front.

 

It is the safest place. All current tanks are optimized for anti-tank warfare, which means the armor of the tank is designed to protect the frontal 60° arc of the vehicle. By placing the ammo directly behind the hull armor, the largest amount of the frontal 60° arc of the the ammo is protected by the tank's thick frontal armor. Moving the ammunition away from the armor, means it is more exposed, as less of it is covered by the tank's frontal armor.

 

One thing I have been pondering about lately is:

It is possible to extend the ammunition rack to the whole width of the bustle?

Removing the pumps and old FCS should clear up space. Alternative you could add a auto loader like the Leclercs if you need it for the 130mm gun. 

 

So you can either:

Install a autoloader.

Increase ammunition capacity.

Or move more ammunition to the turret.

 

Would this be too expensive? 

 

The hull rack could be made into a armored wet storage rack, with fuel tanks on the side for added protection. But I have a feeling they would simply leave it as it is for increased ammunition capacity.

It is possible to extend the ammo rack to the whole width of the bustle; Rheinmetall once proposed to fit a semi-automatic loader at the bustle containing all ammunition. However storing all ammunition in one place is not an ideal design decision, because this means you have to put enough armor at this place to survive anti-tank weapons; otherwise your ammo rack will be hit and the tank is useless. This is why the M1 Abrams' bustle has the same armor protection as the crew compartment.

 

The 130 mm gun will need an autoloader.

 

Rheinmetall claims that their Leopard 2 Revolution tank has a new "decoupled ammunition bunker". I am not sure if this also has a blow-out compartment or is just a fancy new term for ammo rack.

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Now it's Ariete bashing time. The Italian engineers had no knowledge of manufacturing proper tanks (even the OF-40 export tank was largley based on Leopard 1 components; in fact the original hull design was made by German companies), so the Ariete is a bit special.
 
It's turret has extremely thin side armor, some say it's spaced armor, other people claim it's normal steel armor or composite. Judged by the thickness of the ammunition hatch, it's side armor might be 100-150 mm thick.
 

HApousZ.jpg?1


 
Looks kind of like the Leopard 1A3's ammunition hatch. The hull side armor however is more than average, because it extends along the whole hull sides (whereas tanks like the Leopard 2 and Abrams have thin armor at the engine compartment).
 
CjRDH0Y.jpg
 
This might be ~60 mm armor at the engine compartment vs the Leopard 2's 40 mm and Abrams' 38 mm. Btw. did I forget to mention, that the ammunition in the Ariete's turret is stored like in the M48 tank?
 
There are armor upgrades; a PSO package used in Iraq and a frontal turret armor upgrade, which apparently hasn't been purchased yet.

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If you are talking about crew survivability, the frontal fuel tanks of the Abrams might be an advantage. On the other hand, once the fuel tanks are hit and the fuel is incinerated, the tank has be abandoned unless you want to eat fried Abrams tankers.

The fuel tanks of the Abrams are more likely to be incinerated, because of the thinner side armor compared to the Leopard 2. The Leclerc might have the best hull armor design (at least as long as there is no AMAP/MEXAS-H armor), but it's lower front is not protected by composite armor.

 

 

The fuel cells in the Abrams are separated from the crew, so a hit would need to penetrate it, start a leak, and also ignite it.  And then spread inside the tank.  And then prove absolutely impossible for the built-in automatic fire extinguisher to put out for some reason.  A fire on the outside of a tank is simply not that threatening to things on the inside:

 

 

Furthermore, a JP-8 fire can be extinguished (say, by the automatic halon fire suppression system that every Abrams has), unlike an ammunition fire, which categorically cannot be put out once it gets going.

 

And this is essentially kerosene we're talking about, not the easiest stuff in the world to catch on fire:

 

 

 

It is the safest place. All current tanks are optimized for anti-tank warfare, which means the armor of the tank is designed to protect the frontal 60° arc of the vehicle. By placing the ammo directly behind the hull armor, the largest amount of the frontal 60° arc of the the ammo is protected by the tank's thick frontal armor. Moving the ammunition away from the armor, means it is more exposed, as less of it is covered by the tank's frontal armor.

 

 

Except that turret armor is thicker than hull armor.  By that logic, putting the ammunition directly behind the turret cheeks would be the safest possible location.

But the Leo 2's designers must have been very confident in their location of the hull ammo rack, seeing as they didn't bother to isolate it from the crew at all, unlike the designers of the inferior Abrams, who were so terrified of their paper creation being penetrated in the hull rear that they even put blowoff panels and blast doors on the hull ammunition storage:

 

UYLr7Gs.jpg

 

 

 

It is possible to extend the ammo rack to the whole width of the bustle; Rheinmetall once proposed to fit a semi-automatic loader at the bustle containing all ammunition. However storing all ammunition in one place is not an ideal design decision, because this means you have to put enough armor at this place to survive anti-tank weapons; otherwise your ammo rack will be hit and the tank is useless. This is why the M1 Abrams' bustle has the same armor protection as the crew compartment.

 

 

The armor on the turret sides over the ammunition storage of the Abrams might be thicker than the armor over the turret sides of the crew compartment.  Go to 2:32 in this video:

 

You can see that the crew compartment is wider that the ammunition storage.

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It is the safest place. All current tanks are optimized for anti-tank warfare, which means the armor of the tank is designed to protect the frontal 60° arc of the vehicle. By placing the ammo directly behind the hull armor, the largest amount of the frontal 60° arc of the the ammo is protected by the tank's thick frontal armor. Moving the ammunition away from the armor, means it is more exposed, as less of it is covered by the tank's frontal armor.

 

 

I disagree. While true that it is protected by the frontal armor, would it not be also true that a center-placed ammo rack is also protected by the frontal armor? The difference here is that a penetrating shot has more distance to travel until it can hit the ammo, meaning it will have a far lower chance of actually being hit by high speed fragments as it will be saved by modules between it and the armor. However, not the case in the Leopard.

 

That is, if it's taking hits from the front.

 

If it takes hits to the sides or to the belly (IED/mines), then ammo placement doesn't matter because with any design, it would be just as easy to hit. 

 

Tank armor doesn't completely prevent a modern KEP's penetration. It just determines how much range has to be between the tanks until a penetrating shot can be scored. With Russia's new 1-piece ammo and improved 125mm gun, I'm pretty sure a T-14 can penetrate the hull front of a Leopard 2 at decent range. And since we can never actually guarantee a certain place in the tank will be completely impregnable to all threats, it's important to design a fail-safe solution. 

 

This is exactly why I am critical of the T-14's design (crew located at frontal section). Although it was a compromise due to the general design, it's still a flaw.

 

However, for both points I do admit that for any tank, a hull down position is an ideal situation and thus protection features should be focused on the turret. 

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So basically in a conventional layout, this is the most optimal way?:

KqSeze4.png

 

All the ammunition rack have blow out panels and are armored.  The auto loader is a Leclerc style bustle auto loader. The fuel in the sponsons are optional, when the front cant fit more fuel, it is stored in the sponsons. 

Side exhausts to avoid spewing smoke in the face of the infantry.

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Is that a driver-in-turret config, or is the driver buried in the hull along with the fuel?


I don't know about optimal, but that seems pretty good.  Conceivably all the ammo could be located in the hull, and an autoloader could pluck it out and handle it round by round into the breech.  The Swiss NKPZ was going to work like this:

 

zviMXgu.jpg

 

Object 187's glacis design seems like an improvement too:

 

qCYwLWD.jpg

 

Instead of having an extremely sloped glacis that meets the turret ring, it has a somewhat less sloped glacis and a long flat section.  This avoids the weak zone where the turret ring meets the glacis seen on... just about every current MBT, actually.

It would reduce the driver's visibility, but with the wondrous cameras now available this could be less of a problem.

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So basically in a conventional layout, this is the most optimal way?:

KqSeze4.png

 

All the ammunition rack have blow out panels and are armored.  The auto loader is a Leclerc style bustle auto loader. The fuel in the sponsons are optional, when the front cant fit more fuel, it is stored in the sponsons. 

Side exhausts to avoid spewing smoke in the face of the infantry.

 

 

This is cross section of Object 490, so in 1980s designers were looking at such layout.

img003.jpg

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The fuel cells in the Abrams are separated from the crew, so a hit would need to penetrate it, start a leak, and also ignite it.  And then spread inside the tank.  And then prove absolutely impossible for the built-in automatic fire extinguisher to put out for some reason.  A fire on the outside of a tank is simply not that threatening to things on the inside:

 

Furthermore, a JP-8 fire can be extinguished (say, by the automatic halon fire suppression system that every Abrams has), unlike an ammunition fire, which categorically cannot be put out once it gets going.

 

And this is essentially kerosene we're talking about, not the easiest stuff in the world to catch on fire:

Come on, were are talking about something that is capable of penetrating the Abrams' hull armor; so essentially a tank round or some sort of modern anti-tank weaponry (RPG, ATGM, EFP). There shouldn't be much doubt about the JP-8 being incinerated in such a case. Btw. diesel has a higher flash point than JP-8 and is often set on fire during combat.

As for the video of the burning T-80U; there are huge differences to our hypothetical scenario. First of all there are several hundred gallons of fuel in an Abrams (most of which is stored in the front), not just a tiny bit. The fuel tanks are not insulated from the interior, there would be only a small amount of steel and foam between the fire and the crew, while the T-80U has about two feet of composite armor including non-metallic materials (with much lower thermal conductivity than the Abrams' fuel tanks).

 

The automatic fire extinguishers might work in some cases, but they most likely not designed to extingusih the fire of the main fuel tanks. The amount of halon seems to be more limited. I don't know; actually I was talking about the fuel being on fire without the crew compartment being penetrated.

 

Fire_suppression_system_1.jpg

 

 

Except that turret armor is thicker than hull armor.  By that logic, putting the ammunition directly behind the turret cheeks would be the safest possible location.

Yes and no. The turret armor is not thicker, if you take a look along the complete 60° frontal arc. But even if it was, there still is another difference: the turret is more likely being hit (depending on source, up to 75% of all hits occur on the turret). Moving the ammo to a place with lower likelyhood of it being hit, is the first step to make the tank more survivable.

 

Except that turret armor is thicker than hull armor. By that logic, putting the ammunition directly behind the turret cheeks would be the safest possible location.

But the Leo 2's designers must have been very confident in their location of the hull ammo rack, seeing as they didn't bother to isolate it from the crew at all, unlike the designers of the inferior Abrams, who were so terrified of their paper creation being penetrated in the hull rear that they even put blowoff panels and blast doors on the hull ammunition storage:

There is absolutely no need to become huffy and feel insulted. Everything I said is either based on a direct source or can be measured. I have read about and seen (although not in person) many cases of vehicles starting to burn after the fuel tanks were penetrated. This is why I wrote about this previously.

 

I don't think the Leopard 2's hull design is a genius idea and the very optimal design; however I also don't think it is horrible and (a lot) worse than the Abrams hull design. In the end every design decision on an armored vehicle is a trade-off between multiple different factors. While people online are always very eager to praise the Abrams hull design, there is one major issue about it that bogs me: nobody cared about using the same design. The Leopard 2, the Leclerc, the Challengers, the K1, the Type 90, the Ariete, GM's XM1 design, hell even the brand new built-from-blueprint tanks such as the Type 10, K2 Black Panther and Altay have the same "dumb ammo storage" as the Leopard 2.

 

So I cannot believe that it is inherently bad. What is the likelyhood of the frontal armor being penetrated and the ammo being incinerated without the crew dieing? Is there enough time to leave the tank before the ammo completely explodes (after initially being set on fire) for the crew to leave? Maybe these questions play a major role in tank designing; I don't have answers to them, but the people who should have access to such data (the people responsible for designing tanks) choose the dumb Leopard 2's layout.

 

I'd personally love to see the same ammo storage layout, but fitted with blow-off panels and a proper isolated compartment.

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Is that a driver-in-turret config, or is the driver buried in the hull along with the fuel?

I don't know about optimal, but that seems pretty good.  Conceivably all the ammo could be located in the hull, and an autoloader could pluck it out and handle it round by round into the breech.  The Swiss NKPZ was going to work like this:

 

zviMXgu.jpg

 

Object 187's glacis design seems like an improvement too:

 

qCYwLWD.jpg

 

Instead of having an extremely sloped glacis that meets the turret ring, it has a somewhat less sloped glacis and a long flat section.  This avoids the weak zone where the turret ring meets the glacis seen on... just about every current MBT, actually.

It would reduce the driver's visibility, but with the wondrous cameras now available this could be less of a problem.

Yeah, the idea was for the driver to be up front like in the M1, protected by the fuel. 

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I disagree. While true that it is protected by the frontal armor, would it not be also true that a center-placed ammo rack is also protected by the frontal armor? The difference here is that a penetrating shot has more distance to travel until it can hit the ammo, meaning it will have a far lower chance of actually being hit by high speed fragments as it will be saved by modules between it and the armor. However, not the case in the Leopard.

 

That is, if it's taking hits from the front.

 

If it takes hits to the sides or to the belly (IED/mines), then ammo placement doesn't matter because with any design, it would be just as easy to hit. 

 

Tank armor doesn't completely prevent a modern KEP's penetration. It just determines how much range has to be between the tanks until a penetrating shot can be scored. With Russia's new 1-piece ammo and improved 125mm gun, I'm pretty sure a T-14 can penetrate the hull front of a Leopard 2 at decent range. And since we can never actually guarantee a certain place in the tank will be completely impregnable to all threats, it's important to design a fail-safe solution. 

 

This is exactly why I am critical of the T-14's design (crew located at frontal section). Although it was a compromise due to the general design, it's still a flaw.

 

However, for both points I do admit that for any tank, a hull down position is an ideal situation and thus protection features should be focused on the turret. 

 

 

TbhGq66.png

The further away from the front, the more exposed is the ammo. Traveling through more distance won't realistically affect the penetration power of an APFSDS/hollow charge jet or it's fragements. It will be enough to set the ammo on fire.

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Come on, were are talking about something that is capable of penetrating the Abrams' hull armor; so essentially a tank round or some sort of modern anti-tank weaponry (RPG, ATGM, EFP). There shouldn't be much doubt about the JP-8 being incinerated in such a case. Btw. diesel has a higher flash point than JP-8 and is often set on fire during combat.

As for the video of the burning T-80U; there are huge differences to our hypothetical scenario. First of all there are several hundred gallons of fuel in an Abrams (most of which is stored in the front), not just a tiny bit. The fuel tanks are not insulated from the interior, there would be only a small amount of steel and foam between the fire and the crew, while the T-80U has about two feet of composite armor including non-metallic materials (with much lower thermal conductivity than the Abrams' fuel tanks).

 

 

An uncontrolled fire inside the hull, whether it's a big fuel tank or the ammo would require evacuation of the tank.  There's just too much energy in that stuff; the heat in ammo cooking off is frequently enough to de-temper the torsion bars, which is why knocked-out tanks frequently sink into their own suspensions.

 

But to put out a fuel tank fire, one need only deprive it of oxygen.  There only needs to be enough halon to displace the oxygen entering the burning fuel tank to get the fire to go out.  In principle you could even displace the oxygen in the fuel tanks with an inert gas as the fuel is consumed (such systems are standard on fighter aircraft) and render it very hard indeed to ignite.  It's also fairly easy to make the fuel tanks cellular so that only a small portion is threatened at any time.  The cellular divisions could also help disrupt HEAT jets; there have been studies of such cellular fuel tanks that have a mass efficiency of 3 vs RHA against HEAT threats.  Fuel is pretty damned effective armor, and since you're going to be carrying around a bunch of it anyway...

 

AFAIK the Abrams' fuel cells are just big, dumb fuel containers, but upgraded fuel tanks are a part of the M1A3 program.

 

Whereas ammo, once it gets going, effectively cannot be extinguished.  So wherever you end up putting the ammo, it had better be isolated and under blowoff panels.

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But to put out a fuel tank fire, one need only deprive it of oxygen.  There only needs to be enough halon to displace the oxygen entering the burning fuel tank to get the fire to go out.

When you penetrate a fuel tank, there are two holes from which oxygen can enter. One at the interior of the MBT, one at the place where the penetrator originally impacted. I am no expert for halon gases, but it seems somewhat unlikely that it is capable of exiting the tank through the penetration hole and is capable of completely blocking all air of entering. While Halon has a lower density than air, there still is Fick's law... this topic might need further research.

 

It's also fairly easy to make the fuel tanks cellular so that only a small portion is threatened at any time.  The cellular divisions could also help disrupt HEAT jets; there have been studies of such cellular fuel tanks that have a mass efficiency of 3 vs RHA against HEAT threats.  Fuel is pretty damned effective armor, and since you're going to be carrying around a bunch of it anyway...

 

I don't know your source, but a few years ago there was a discussion on the TankNet forums, where somebody claimed that fuel hat a ME of 3 vs HEAT. After he posted a link to a research paper, it became clear that this included the (relatively thick) steel walls of the fuel tanks.

 

According to Israel Tal, fuel was found to be about 1/7 as efficient against HEAT as steel of the same thickness. This matches the expectations of the density law.

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In the "Theoretical Study of a Diesel-Filled Airtight Structure Unit Subjected to Shaped Charge Jet Impact" study done by Zhen-Yu Gao et al, there is no mention of the fuel starting to burn or there being a danger of fire.

 

I don't know your source, but a few years ago there was a discussion on the TankNet forums, where somebody claimed that fuel hat a ME of 3 vs HEAT. After he posted a link to a research paper, it became clear that this included the (relatively thick) steel walls of the fuel tanks.
That doesn't matter all that much. Steel armour perpendicular to the hydrodynamic jet will barely have an effect on the total penetration capabilities. For every 1 cm of penetration in steel, the hydrodynamic jet loses 0.94 cm of length. And if he includes the steel walls in the calculation for relative effectiveness vs RHA and still gets a factor of three, doesn't that mean the fuel is even more effective than calculated, since the steel walls will have a relative effectiveness of ~1?

 

For diesel however it's different because that has a secondary effect where the diesel implodes onto the penetrating hydrodynamic jet, slowing it down and thus decreasing jet velocity. This effect does not happen in solids.

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      SUBJ: RFP for new battle tank

      1.      Background.
      As part of the War of 2248 against the Perfidious Cascadians, great deficiencies were discovered in the Heavy tank DF-1. As detailed in report [REDACTED], the DF-1 was quite simply no match for the advanced weaponry developed in secret by the Cascadian entity. Likewise, the DF-1 has fared poorly in the fighting against the heretical Mormonhideen, who have developed many improvised weapons capable of defeating the armor on this vehicle, as detailed in report [REDACTED]. The Extended War on the Eastern Front has stalled for want of sufficient survivable firepower to push back the Mormon menace beyond the Colorado River south of the Vegas Crater.
      The design team responsible for the abject failure that was the DF-1 have been liquidated, which however has not solved the deficiencies of the existing vehicle in service. Therefore, a new vehicle is required, to meet the requirements of the People’s Auditory Forces to keep the dream of our lord and prophet alive.


       
      Over the past decade, the following threats have presented themselves:

      A.      The Cascadian M-2239 “Norman” MBT and M-8 light tank

      Despite being approximately the same size, these 2 vehicles seem to share no common components, not even the primary armament! Curiously, it appears that the lone 120mm SPG specimen recovered shares design features with the M-8, despite being made out of steel and not aluminum like the light tank. (based on captured specimens from the battle of Crater Lake, detailed in report [REDACTED]).
      Both tanks are armed with high velocity guns.

      B.      The Cascadian BGM-1A/1B/1C/1D ATGM

      Fitted on a limited number of tank destroyers, several attack helicopters, and (to an extent) man-portable, this missile system is the primary Cascadian anti-armor weapon other than their armored forces. Intelligence suggests that a SACLOS version (BGM-1C) is in LRIP, with rumors of a beam-riding version (BGM-1D) being developed.

      Both warheads penetrate approximately 6 cone diameters.

      C.      Deseret tandem ATR-4 series
      Inspired by the Soviet 60/105mm tandem warhead system from the late 80s, the Mormon nation has manufactured a family of 2”/4” tandem HEAT warheads, launched from expendable short-range tube launchers, dedicated AT RRs, and even used as the payload of the JS-1 MCLOS vehicle/man-portable ATGM.
      Both warheads penetrate approximately 5 cone diameters.

      D.      Cascadian HEDP 90mm rocket
      While not a particularly impressive AT weapon, being of only middling diameter and a single shaped charge, the sheer proliferation of this device has rendered it a major threat to tanks, as well as lighter vehicles. This weapon is available in large numbers in Cascadian infantry squads as “pocket artillery”, and there are reports of captured stocks being used by the Mormonhideen.
      Warhead penetrates approximately 4 cone diameters.

      E.      Deseret 40mm AC/ Cascadian 35mm AC
      These autocannon share broadly similar AP performance, and are considered a likely threat for the foreseeable future, on Deseret armored cars, Cascadian tank destroyers, and likely also future IFVs.

      F.      IEDs

      In light of the known resistance of tanks to standard 10kg anti-tank mines, both the Perfidious Cascadians and the Mormonhideen have taken to burying larger anti-tank A2AD weaponry. The Cascadians have doubled up some mines, and the Mormons have regularly buried AT mines 3, 4, and even 5 deep.

      2.      General guidelines:

      A.      Solicitation outline:
      In light of the differing requirements for the 2 theaters of war in which the new vehicle is expected to operate, proposals in the form of a field-replaceable A-kit/B-kit solution will be accepted.

      B.      Requirements definitions:
      The requirements in each field are given in 3 levels- Threshold, Objective, and Ideal.
      Threshold is the minimum requirement to be met; failure to reach this standard may greatly disadvantage any proposal.

      Objective is the threshold to be aspired to; it reflects the desires of the People’s Auditory Forces Armored Branch, which would prefer to see all of them met. At least 70% must be met, with bonus points for any more beyond that.

      Ideal specifications are the maximum of which the armored forces dare not even dream. Bonus points will be given to any design meeting or exceeding these specifications.

      C.      All proposals must accommodate the average 1.7m high Californian recruit.

      D.      The order of priorities for the DPRC is as follows:

      a.      Vehicle recoverability.

      b.      Continued fightability.

      c.       Crew survival.

      E.      Permissible weights:

      a.      No individual field-level removable or installable component may exceed 5 tons.

      b.      Despite the best efforts of the Agriculture Command, Californian recruits cannot be expected to lift weights in excess of 25 kg at any time.

      c.       Total vehicle weight must remain within MLC 120 all-up for transport.

      F.      Overall dimensions:

      a.      Length- essentially unrestricted.

      b.      Width- 4m transport width.

                                                                    i.     No more than 4 components requiring a crane may be removed to meet this requirement.

                                                                   ii.     Any removed components must be stowable on top of the vehicle.

      c.       Height- The vehicle must not exceed 3.5m in height overall.

      G.     Technology available:

      a.      Armor:
      The following armor materials are in full production and available for use. Use of a non-standard armor material requires permission from a SEA ORG judge.
      Structural materials:

                                                                    i.     RHA/CHA

      Basic steel armor, 250 BHN. The reference for all weapon penetration figures, good impact properties, fully weldable. Available in thicknesses up to 150mm (RHA) or 300mm (CHA).
      Density- 7.8 g/cm^3.

                                                                   ii.     Aluminum 5083

      More expensive to work with than RHA per weight, middling impact properties, low thermal limits. Excellent stiffness.

       Fully weldable. Available in thicknesses up to 100mm.
      Mass efficiency vs RHA of 1 vs CE, 0.9 vs KE.
      Thickness efficiency vs RHA of 0.33 vs CE, 0.3 vs KE.
      Density- 2.7 g/cm^3 (approx. 1/3 of steel).

      For structural integrity, the following guidelines are recommended:

      For light vehicles (less than 40 tons), not less than 25mm RHA/45mm Aluminum base structure

      For heavy vehicles (70 tons and above), not less than 45mm RHA/80mm Aluminum base structure.
      Intermediate values for intermediate vehicles may be chosen as seen fit.
      Non-structural passive materials:

                                                                  iii.     HHA

      Steel, approximately 500 BHN through-hardened. Approximately twice as effective as RHA against KE and HEAT on a per-weight basis. Not weldable, middling shock properties. Available in thicknesses up to 25mm.
      Density- 7.8g/cm^3.

                                                                  iv.     Glass textolite

      Mass efficiency vs RHA of 2.2 vs CE, 1.64 vs KE.

      Thickness efficiency vs RHA of 0.52 vs CE, 0.39 vs KE.
      Density- 1.85 g/cm^3 (approximately ¼ of steel).
      Non-structural.

                                                                   v.     Fused silica

      Mass efficiency vs RHA of 3.5 vs CE, 1 vs KE.

      Thickness efficiency vs RHA of 1 vs CE, 0.28 vs KE.
      Density-2.2g/cm^3 (approximately 1/3.5 of steel).
      Non-structural, requires confinement (being in a metal box) to work.

                                                                  vi.     Fuel

      Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE.

      Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE.

      Density-0.82g/cm^3.

                                                                vii.     Assorted stowage/systems

      Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE.

                                                               viii.     Spaced armor

      Requires a face of at least 25mm LOS vs CE, and at least 50mm LOS vs KE.

      Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 10 cm air gap.
      Spaced armor rules only apply after any standoff surplus to the requirements of a reactive cassette.

      Reactive armor materials:

                                                                  ix.     ERA-light

      A sandwich of 3mm/3mm/3mm steel-explodium-steel.
      Requires mounting brackets of approximately 10-30% cassette weight.

      Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).

                                                                   x.     ERA-heavy

      A sandwich of 15mm steel/3mm explodium/9mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).

                                                                  xi.     NERA-light

      A sandwich of 6mm steel/6mm rubber/ 6mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.

                                                                 xii.     NERA-heavy

      A sandwich of 30mm steel/6m rubber/18mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.

      The details of how to calculate armor effectiveness will be detailed in Appendix 1.

      b.      Firepower

                                                                    i.     2A46 equivalent tech- pressure limits, semi-combustible cases, recoil mechanisms and so on are at an equivalent level to that of the USSR in the year 1960.

                                                                   ii.     Limited APFSDS (L:D 15:1)- Spindle sabots or bourelleted sabots, see for example the Soviet BM-20 100mm APFSDS.

                                                                  iii.     Limited tungsten (no more than 100g per shot)

                                                                  iv.     Californian shaped charge technology- 5 CD penetration for high-pressure resistant HEAT, 6 CD for low pressure/ precision formed HEAT.

                                                                   v.     The general issue GPMG for the People’s Auditory Forces is the PKM. The standard HMG is the DShK.

      c.       Mobility

                                                                    i.     Engines tech level:

      1.      MB 838 (830 HP)

      2.      AVDS-1790-5A (908 HP)

      3.      Kharkov 5TD (600 HP)

                                                                   ii.     Power density should be based on the above engines. Dimensions are available online, pay attention to cooling of 1 and 3 (water cooled).

                                                                  iii.     Power output broadly scales with volume, as does weight. Trying to extract more power from the same size may come at the cost of reliability (and in the case of the 5TD, it isn’t all that reliable in the first place).

                                                                  iv.     There is nothing inherently wrong with opposed piston or 2-stroke engines if done right.

      d.      Electronics

                                                                    i.     LRFs- unavailable

                                                                   ii.     Thermals-unavailable

                                                                  iii.     I^2- limited

      3.      Operational Requirements.

      The requirements are detailed in the appended spreadsheet.

      4.      Submission protocols.

      Submission protocols and methods will be established in a follow-on post, nearer to the relevant time.
       
      Appendix 1- armor calculation
      Appendix 2- operational requirements
       
      Good luck, and may Hubbard guide your way to enlightenment!
    • By Collimatrix
      Shortly after Jeeps_Guns_Tanks started his substantial foray into documenting the development and variants of the M4, I joked on teamspeak with Wargaming's The_Warhawk that the next thing he ought to do was a similar post on the T-72.
       
      Haha.  I joke.  I am funny man.
       
      The production history of the T-72 is enormously complicated.  Tens of thousands were produced; it is probably the fourth most produced tank ever after the T-54/55, T-34 and M4 sherman.
       
      For being such an ubiquitous vehicle, it's frustrating to find information in English-language sources on the T-72.  Part of this is residual bad information from the Cold War era when all NATO had to go on were blurry photos from May Day parades:
       

       
      As with Soviet aircraft, NATO could only assign designations to obviously externally different versions of the vehicle.  However, they were not necessarily aware of internal changes, nor were they aware which changes were post-production modifications and which ones were new factory variants of the vehicle.  The NATO designations do not, therefore, necessarily line up with the Soviet designations.  Between different models of T-72 there are large differences in armor protection and fire control systems.  This is why anyone arguing T-72 vs. X has completely missed the point; you need to specify which variant of T-72.  There are large differences between them!
       
      Another issue, and one which remains contentious to this day, is the relation between the T-64, T-72 and T-80 in the Soviet Army lineup.  This article helps explain the political wrangling which led to the logistically bizarre situation of three very similar tanks being in frontline service simultaneously, but the article is extremely biased as it comes from a high-ranking member of the Ural plant that designed and built the T-72.  Soviet tank experts still disagree on this; read this if you have some popcorn handy.  Talking points from the Kharkov side seem to be that T-64 was a more refined, advanced design and that T-72 was cheap filler, while Ural fans tend to hold that T-64 was an unreliable mechanical prima donna and T-72 a mechanically sound, mass-producible design.
       
      So, if anyone would like to help make sense of this vehicle, feel free to post away.  I am particularly interested in:
       
      -What armor arrays the different T-72 variants use.  Diagrams, dates of introduction, and whether the array is factory-produced or a field upgrade of existing armor are pertinent questions.
       
      -Details of the fire control system.  One of the Kharkov talking points is that for most of the time in service, T-64 had a more advanced fire control system than contemporary T-72 variants.  Is this true?  What were the various fire control systems in the T-64 and T-72, and what were there dates of introduction?  I am particularly curious when Soviet tanks got gun-follows-sight FCS.
       
      -Export variants and variants produced outside the Soviet Union.  How do they stack up?  Exactly what variant(s) of T-72 were the Iraqis using in 1991?

      -WTF is up with the T-72's transmission?  How does it steer and why is its reverse speed so pathetically low?
       
       
    • By Proyas
      Hi guys,
       
      I recently read about upgrade packages to old tanks like the M-60 and T-55, but kept seeing comments from people saying they would still be obsolete. Is this because the M-60 and T-55 are made entirely of steel (and not composite) armor?  
       
      I have this theory that thick steel armor is probably totally obsolete, and is just dead weight in the age of lighter weight composite armor. You can bolt on upgrades to an M-60 or T-55, but you're still hamstrung by the fact that either tank will be carrying around tons of useless steel. Am I right? 
       
      Also, if we wanted to upgrade old tanks like that, wouldn't the best idea be to develop a new turret--with lighter, modern composite armor and better technology inside--and just drop it into the old tanks? The hulls would still be made of heavy steel, but that could be helped a bit by adding applique armor. 
       
      Here are some of the upgrades I read about: 
       
      https://youtu.be/NG89Zh9qQrQ
       
      http://www.army-guide.com/eng/product1907.html
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