HEAT vs APHE

[ddmauro7 26]

Hello all, I hope this is in the correct section as I assumed machinery of war included their ammunition. I was wondering how, in real life, does HEAT measure up to APHE in terms of post-pen effect. They both should have some explosive effect after penetrating amour I think? Thanks in advance to anyone who can help me understand!

[PlumleyBT 2,979]

HEAT doesn't have a real explosive effect inside the target.

tl;dr: the shaped charge is used to melt and pierce the target's armor with gases thanks to high temperature and pressure while the copper cone isn't the real penetrator.

So the post pen damage is created by shrapnels and the expanded gas.

APHE have a explosive filler that is supposed to detonate inside the target after penetration.

[TheFuzzieOne 3,355]

4 hours ago, ddmauro7 said:

Hello all, I hope this is in the correct section as I assumed machinery of war included their ammunition. I was wondering how, in real life, does HEAT measure up to APHE in terms of post-pen effect. They both should have some explosive effect after penetrating amour I think? Thanks in advance to anyone who can help me understand!

 

How APHE functions in game is hilariously inaccurate. In reality they aren't a 360 grenade that goes off. They actually function more akin to how AP works in game, it's more like a forward cone of a slightly different spread. Its misrepresentation in game is one of the oldest problems there is.

 

HEAT in game a fairly decent simplistic representation of it. But I stress the "simplistic" part. (And putting aside the hedge nonsense.)

Edited September 6, 2020 by TheFuzzieOne

[ddmauro7 26]

ahhhh thank you both, very interesting.

[Silent_Witch 1,452]

A common misconception of HEAT

HEAT utilized shaped charge, it is place behind a conical hollow ductile metal (usually copper). the exposive pressure drive the "copper cone" inward to collapse. This result the copper cone turn into a "carrot" shape, with a hypersonic tips and slower slug (tail). When this hypersonic tip impact on armour, it generate a pressure so enormous the metal grain on the armour no longer able to keep it's strength and turn into "fluid stage" for that moment.

The slug tail travelling at a much slower speed, hence it have to push away the armour and this slug is where the damage come from (spalling)

[AraMacao 1,164]

9 hours ago, Silent_Witch said:

... This result the copper cone turn into a "carrot" shape, with a hypersonic tips and slower slug (tail). ...

I live the fact that you describe the copper beam as a carrot. 

Eat my carrot tiger 2!

[Silent_Witch 1,452]

30 minutes ago, AraMacao said:

I live the fact that you describe the copper beam as a carrot. 

Eat my carrot tiger 2!

My English vocabulary are limited, couldn’t think of any word to describe the slim tip and fat tail

[PlumleyBT 2,979]

12 hours ago, Silent_Witch said:

. When this hypersonic tip impact on armour

No, the copper cone is used to compress at high temperatures and pressures the gases between it and the armor, this generate a jet stream that nullify the armor thickness and resistance, the copper penetrator do the rest.

But the armor is already defeated even before the copper slug penetrate

[AraMacao 1,164]

22 minutes ago, PlumleyBT said:

No, the copper cone is used to compress at high temperatures and pressures the gases between it and the armor, this generate a jet stream that nullify the armor thickness and resistance, the copper penetrator do the rest.

But the armor is already defeated even before the copper slug penetrate

Wat ... The copper pushes the air in front of it and that's what digs a hole in the target?  So a shaped charge would not work in space?

[TheGaiaphage 118]

The copper cone is the penetrator:

 

https://www.researchgate.net/publication/337544828_Determination_of_Shaped_Charge_Jet_Characteristics_Using_a_Neural_Networks_Model_Based_on_Hydrocode_Simulations

 

[PlumleyBT 2,979]

6 hours ago, AraMacao said:

Wat ... The copper pushes the air in front of it and that's what digs a hole in the target?  So a shaped charge would not work in space?

"When the charge is detonated by the fuze mounted in the nose, a jet of high-energy gas and vaporised metal from the cone is projected axially forward (the Munroe effect). This jet, travelling at a speed of around 6,000 m per second, burns its way through the armour like a cutting torch."

http://www.army-guide.com/eng/article/article_494.html

 

The cone isn't the penetrator, cause the high energy jet has already pierced the armor.

[aja318 375]

No, HEAT shells do not send molten or vaporised metal into armour, they create VERY FAST jet of metal that impact armour, interaction happen in hydrodynamic regime (both armour and copper jet behave like fluids) so the jet can push through. You can even do experiment in your house, you need container of water and something that will generate water stream, direct your stream of water into water container and observe how it behave.

 

It's not molten.

It's not gas.

It does not burn.

It just goes VERY FAST.

 

Finally, spalling is what happen when fragements of armour are send flying inside protected space and can happen even without armour being breeched (see HESH anti armour function).

[AraMacao 1,164]

11 hours ago, PlumleyBT said:

"When the charge is detonated by the fuze mounted in the nose, a jet of high-energy gas and vaporised metal from the cone is projected axially forward (the Munroe effect). This jet, travelling at a speed of around 6,000 m per second, burns its way through the armour like a cutting torch."

http://www.army-guide.com/eng/article/article_494.html

 

The cone isn't the penetrator, cause the high energy jet has already pierced the armor.

If gases is what's doing that digging then this illustration would be incorrect. It shows a shaped charge without metal cone (liner) achieving less penetration than one with cone.

[MaximumSomething 58]

17 hours ago, PlumleyBT said:

"When the charge is detonated by the fuze mounted in the nose, a jet of high-energy gas and vaporised metal from the cone is projected axially forward (the Munroe effect). This jet, travelling at a speed of around 6,000 m per second, burns its way through the armour like a cutting torch."

http://www.army-guide.com/eng/article/article_494.html

 

The cone isn't the penetrator, cause the high energy jet has already pierced the armor.

 

That is just not the case. This is from the US Army Research Laboratory: https://apps.dtic.mil/sti/pdfs/ADA469696.pdf  If you don't want to read it that's fine, powerpoint presentations are often hard to follow without the lecture to go with it, but it has pictures and things to help show some of what is going on and that might help. The high points: pg.5 the tip is moving around 10km/s but is only 400-500C, so something like lead or zinc would be molten, materials like aluminium, copper, or steel will still be solid. pg.16 It's under "misnomers" but near enough, no plasma, no melting, no 20,000C, no burning cutting torch, no super density material.

[ddmauro7 26]

ill read it, I'm more of a visual learner.

[PlumleyBT 2,979]

4 hours ago, MaximumSomething said:

 

That is just not the case. This is from the US Army Research Laboratory: https://apps.dtic.mil/sti/pdfs/ADA469696.pdf  If you don't want to read it that's fine, powerpoint presentations are often hard to follow without the lecture to go with it, but it has pictures and things to help show some of what is going on and that might help. The high points: pg.5 the tip is moving around 10km/s but is only 400-500C, so something like lead or zinc would be molten, materials like aluminium, copper, or steel will still be solid. pg.16 It's under "misnomers" but near enough, no plasma, no melting, no 20,000C, no burning cutting torch, no super density material.

A new method was used to analyze shaped charges and results showed that the tip (not the slug or "carrot") has a temperature of 1200K, with its hypersonic speed its enough to nullify material strenghts.

https://www.sciencedirect.com/science/article/pii/S1877705813009144?via%3Dihub

The slug, which is much slower and colder penetrates a heavily degradated armor.

[Silent_Witch 1,452]

10 hours ago, ddmauro7 said:

ill read it, I'm more of a visual learner.

Both HEAT and HESH utlized condense matter response under shock loading, but HEAT and HESH work in very different way

HEAT make use of high shock loading that the armour no longer able to hold it's strength and behave like fluid for that specific moment

HESH on the other hand toy with impedance using reflection wave to create a stress zone

[MaximumSomething 58]

13 hours ago, PlumleyBT said:

A new method was used to analyze shaped charges and results showed that the tip (not the slug or "carrot") has a temperature of 1200K, with its hypersonic speed its enough to nullify material strenghts.

https://www.sciencedirect.com/science/article/pii/S1877705813009144?via%3Dihub

The slug, which is much slower and colder penetrates a heavily degradated armor.

 

Yes, the energy present in the jet is not evenly distributed, so from that paper (thanks, by the way) the very tip of the jet is hotter at around 860-920C. I would also draw your attention to the fact that experiment was also done in a vacuum, so the statement "the copper cone is used to compress at high temperatures and pressures the gases between it and the armor" certainly can't be true. It's an explosively projected jet of metal doing the penetrating.

[PlumleyBT 2,979]

1 hour ago, MaximumSomething said:

 

Yes, the energy present in the jet is not evenly distributed, so from that paper (thanks, by the way) the very tip of the jet is hotter at around 860-920C. I would also draw your attention to the fact that experiment was also done in a vacuum, so the statement "the copper cone is used to compress at high temperatures and pressures the gases between it and the armor" certainly can't be true. It's an explosively projected jet of metal doing the penetrating.

Thats a huge semplification, i admit it.

But my point stands. For an explosion you need expanding gas at high temperature.

So the vacuum is intended to have a controlled enviriorment or you cant have a explosion at all.

And i want to point out also that with high pressure melting points temperatures decrease, this means that the above mentioned 1200K can be enough to cut through the metal.

So we have the tip, which is a small % of what remains of the metal cone, is separated from the slug in a state that can be considered non solid state, travels at hypersonic speed(more speed=more penetration) hit a degradaded metal armor.

So, i guess, can we consider the armor defeated but not penetrated?

Edited September 9, 2020 by PlumleyBT

[MaximumSomething 58]

I would suggest the vacuum is to prevent atmospheric heating and/or the formation of any plasma that would interfere with the temperature measurement, not for anything to do with the explosion. There isn't enough mass in the tip of the jet for its temperature to really change anything vs. its velocity. Bearing in mind it is late and I've had a couple, the decimal points might wander off. Going off their measurements the tip is around 5mm across and about 15mm long, so roughly cylindrical volume is is 0.29cm^3, copper's density is 8.96g/cm^3 (call it 9) mass will be around 2.6g, specific heat of 0.385J/gC at 1200K comes to 1,225J assuming we allow it to cool to 0K/-273C on contact with a target, which is unlikely. 2.6g at the stated 9.15km/s has a KE of 110,932J. So back-of-the-envelope the tip is near 100:1 KE to thermal, probably more given the unrealistic cooling allowed for, the rest of the jet is likely similar just less energetic, the remains of the cone doesn't really matter after that. I can't see heat as being an important factor in piercing armour.

 

This isn't a real warhead, but I don't think that matters as making it bigger won't help, only making it slower and/or hotter would.