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Tank Myths


Walter_Sobchak
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Myth: During WWII, American tanks weren't supposed to fight enemy tanks. That's what TDs were for.

Chieftain rejogged my memory of this in his little video on the history of TDs.

This one always gets me. McNair gets a lot of press here, but even if people aren't privy to the facts that the turret front plate on the Sherman was removable so they could use the 75 mm gun, a 105 mm howitzer, or an ordnance similar to the 3" antitank gun; or that weapons suites considered for the Sherman included the British 6-pounder antitank gun or even dual 37 mms (used by the infantry as antitank guns); or that work on what would become the 76 mm gun began as soon as it was realized the 3" antitank gun wouldn't fit in the turret, just look at what the US was actually fielding. The medium tank M2 and the light tanks M2A4-M5 were armed with a 37 mm antitank gun, and though the medium tank M3 did have a 75 mm gun that could fire decent HE as well as comfortably take on most tanks, when the designers couldn't put that gun in a turret they kept a turret anyway and armed it with a 37 mm antitank gun. And the first WW2-era attempt at a heavy tank? BOTH 3" and 37 mm antitank guns...
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This one always gets me. McNair gets a lot of press here, but even if people aren't privy to the facts that the turret front plate on the Sherman was removable so they could use the 75 mm gun, a 105 mm howitzer, or an ordnance similar to the 3" antitank gun; or that weapons suites considered for the Sherman included the British 6-pounder antitank gun or even dual 37 mms (used by the infantry as antitank guns); or that work on what would become the 76 mm gun began as soon as it was realized the 3" antitank gun wouldn't fit in the turret, just look at what the US was actually fielding. The medium tank M2 and the light tanks M2A4-M5 were armed with a 37 mm antitank gun, and though the medium tank M3 did have a 75 mm gun that could fire decent HE as well as comfortably take on most tanks, when the designers couldn't put that gun in a turret they kept a turret anyway and armed it with a 37 mm antitank gun. And the first WW2-era attempt at a heavy tank? BOTH 3" and 37 mm antitank guns...

You might almost think the armor board was a little worried about enemy... wait for it... tanks?

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HEAT penetrates due to chemical energy. It doesn't. It penetrates due to kinetic energy.

 

While HEAT does use chemical energy to propel the kinetic energy penetrator, so does every single AP cartridge. A HEAT round just has it at two points, to propel the shell and to propel the kinetic energy penetrator. Whereas with almost all AP shells the shell and penetrator are one and the same.

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This one always gets me. McNair gets a lot of press here, but even if people aren't privy to the facts that the turret front plate on the Sherman was removable so they could use the 75 mm gun, a 105 mm howitzer, or an ordnance similar to the 3" antitank gun; or that weapons suites considered for the Sherman included the British 6-pounder antitank gun or even dual 37 mms (used by the infantry as antitank guns); or that work on what would become the 76 mm gun began as soon as it was realized the 3" antitank gun wouldn't fit in the turret, just look at what the US was actually fielding. The medium tank M2 and the light tanks M2A4-M5 were armed with a 37 mm antitank gun, and though the medium tank M3 did have a 75 mm gun that could fire decent HE as well as comfortably take on most tanks, when the designers couldn't put that gun in a turret they kept a turret anyway and armed it with a 37 mm antitank gun. And the first WW2-era attempt at a heavy tank? BOTH 3" and 37 mm antitank guns...

Glad SOMEBODY has some sense.

Many people let words do their talking for them, so as soon as you label the US tanks as "not antitank weapons", then thought ceases.

This is also a major tactic in the political arena, and a very powerful one.

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Glad SOMEBODY has some sense.

Many people let words do their talking for them, so as soon as you label the US tanks as "not antitank weapons", then thought ceases.

This is also a major tactic in the political arena, and a very powerful one.

That and simple 'if not A, then B' dualism.

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HEAT penetrates due to chemical energy. It doesn't. It penetrates due to kinetic energy.

 

While HEAT does use chemical energy to propel the kinetic energy penetrator, so does every single AP cartridge. A HEAT round just has it at two points, to propel the shell and to propel the kinetic energy penetrator. Whereas with almost all AP shells the shell and penetrator are one and the same.

 

It uses a combination of both chemical and kinetic energy actually.

HEAT shells use a copper liner, which is a cheap but extremely effective conductor.

 

Combine the copper jet's extreme heat and extreme speed and you get the perfect weapon to cut through steel. 

 

But then of course people take it the other way and say it 'melts' the armor, which is also not true.

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It uses a combination of both chemical and kinetic energy actually.

HEAT shells use a copper liner, which is a cheap but extremely effective conductor.

 

Combine the copper jet's extreme heat and extreme speed and you get the perfect weapon to cut through steel. 

 

But then of course people take it the other way and say it 'melts' the armor, which is also not true.

No, this isn't how it works at all.

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It uses a combination of both chemical and kinetic energy actually.

HEAT shells use a copper liner, which is a cheap but extremely effective conductor.

 

Combine the copper jet's extreme heat and extreme speed and you get the perfect weapon to cut through steel. 

 

But then of course people take it the other way and say it 'melts' the armor, which is also not true.

No, absolutely not.

 

The only thing related to thermal energy during hydrodynamic penetration is the impact flash, nothing else.

 

It's still being debated whether or not the jet is actually melted or not. Which doesn't even matter since hydrodynamic penetration does not depend on thermal energy even in the slightest. With hydrodynamic penetration the only thing that has a significant effect on the penetration distance is density. Even the strength of the materials are not always relevant. Yes, they have an effect on penetration, but on very high impact velocities the penetrator strength is assumed to be 0.

 

And no, velocity doesn't matter when you're above the hydrodynamic limit of the materials involved.

 

As a matter of fact, an accurate calculation for the penetration depth of a hydrodynamic penetrator is simply p=L*sqrt(ρpt). Which is to say: Penetration depth = Length of penetrator multiplied by the square root of the penetrator density divided by the target density.

 

Source: "Armour; Materials, Theory and Design" by Paul J. Hazell

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Okay then I stand corrected. 

This is a good attitude.

 

edit: and because tone is hard, let me clarify: I really mean this in an unironic sense. Being able to take input and correct your misconceptions is a rare trait, and you should be commended for doing so.

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  • 3 weeks later...

My "favorite" myths abut tanks:

 

1) Leopard-2AV main  armour was worse then XM1 :-)

2) Leopard-2A4 was inferior in armour protection in compare to M1 and M1IP

3) T-72B was poor protected in compare to western tanks

4) T-80U was poor protected in compare to western tanks

The favorite one:

5) T-72B and T-80B and T-80U and T-64 have therible "Ronson quality" survivialibity on battelfield after hit

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  • 2 years later...
On 8/31/2016 at 12:02 PM, Mighty_Zuk said:

 

It uses a combination of both chemical and kinetic energy actually.

HEAT shells use a copper liner, which is a cheap but extremely effective conductor.

 

Combine the copper jet's extreme heat and extreme speed and you get the perfect weapon to cut through steel. 

 

But then of course people take it the other way and say it 'melts' the armor, which is also not true.

 

A 2013 study by Uhlig and Hummer showed that the outer part of a modern copper-based HEAT jet, in-flight, had a measurable temperature of ~800°C, though more dated experiments at getting temp readings in-flight showed lower numbers (~550°C). 800°C is still far from the melting point of copper (~1100°C) and given the short amount of time a HEAT jet stays in the air before striking its target, it's even more worthless against steel (for reference - depending on their respective grades, stainless steel alloys melt somewhere between 1,375°C and 1,530°C) . As Bronezhilet said, heat (the HEAT acronym really caused a lot of misunderstandings here) has nothing to do with the armor-penetration mechanism of a shaped charge.

 

The HEAT jet simply a semi-liquid spike made from a very dense material (copper, lanthanum or any other alloy thereof), violently compressed by a chemical explosion and made to travel at hypersonic speeds in one very specific, narrow direction. The rest is just pure physical pressure.

 

EDIT: the only part where heat (lowercase) matters is maybe post-penetration, because it means that whatever is on the other side will be hit by a spray of very dense, fast-moving material...and a hot one at that.

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1 hour ago, Peasant said:

Is German tank inferiority in France a myth, overblown, or real?

 

Pz II, 38t, Pz I, (and heavier) Pz III, are more mobile (in terms of fuel range) than their French counterparts?

 

Why does the Pz III get such a bad rep in wehraboo circles? 

 

Anyone who thinks a tiger 2 was a good tank is bound to favour the impenetrable-even-after-being-surrounded french white elephants over tanks that could actually win battles

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My (so far) favourite tank myths :)

 

1. T-34's maximum production rate during WW2 was higher than Sherman's one.

2. Leopard 1 (but without add-on armor) has higher chances of survival on the battlefield than T-72

3. Anders tank is based on CV90 chassis

4. You can't replace / exchange glass laminate plates in T-72A/M chassis

 

And extending to anti-tank things:

5. AT-3 Sagger exists only in MCLOS version

6. Javelin launcher doesn't have a tripod

7. Spike missile uses only a man-in-the-loop guidance

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2 hours ago, Peasant said:

Is German tank inferiority in France a myth, overblown, or real?

 

Pz II, 38t, Pz I, (and heavier) Pz III, are more mobile (in terms of fuel range) than their French counterparts?

 

Why does the Pz III get such a bad rep in wehraboo circles?

 

German tanks in France were chiefly light tanks. The PzIII was available only in small numbers because they had one hell of a time getting production ramped up. 

 

As for a bad rap, probably because you can't put a huge fuckoff gun on the chassis. Interestingly enough, the Soviets liked the PzIII. It was popular to use in captured tank units and there were two SPG designs that used it as a chassis.

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1 hour ago, Renegade334 said:

 

A 2013 study by Uhlig and Hummer showed that the outer part of a modern copper-based HEAT jet, in-flight, had a measurable temperature of ~800°C, though more dated experiments at getting temp readings in-flight showed lower numbers (~550°C). 800°C is still far from the melting point of copper (~1100°C) and given the short amount of time a HEAT jet stays in the air before striking its target, it's even more worthless against steel (for reference - depending on their respective grades, stainless steel alloys melt somewhere between 1,375°C and 1,530°C) . As Bronezhilet said, heat (the HEAT acronym really caused a lot of misunderstandings here) has nothing to do with the armor-penetration mechanism of a shaped charge.

 

The HEAT jet simply a semi-liquid spike made from a very dense material (copper, lanthanum or any other alloy thereof), violently compressed by a chemical explosion and made to travel at hypersonic speeds in one very specific, narrow direction. The rest is just pure physical pressure.

 

EDIT: the only part where heat (lowercase) matters is maybe post-penetration, because it means that whatever is on the other side will be hit by a spray of very dense, fast-moving material...and a hot one at that.

When I said what I said, I really should have rephrased better because now I can see how it can sound very wrong. 

Temperature indeed is a non-factor on the penetration power. It's purely kinetic. Unfortunately, my local ammo 'expert' (knows a lot of history, but not a whole lot about how it actually works) claims the HEAT's defeat mechanism is entirely non-kinetic.

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58 minutes ago, Lord_James said:

Depleted uranium is a terrible material to make ammo and armor out of because it is radioactive and poisons everyone near it ))))) 

Now, it is a heavy metal and not particularly good for you, especially in dust form. And not something you want to be fucking around with needlessly.

 

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6 minutes ago, Belesarius said:

Now, it is a heavy metal and not particularly good for you, especially in dust form. And not something you want to be fucking around with needlessly.

 

 

I was mostly referring to the radioactive part, because something something uranium and radiation. 

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