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#41 KV7

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Posted 18 March 2018 - 0556 AM

 

 

 

 

 

I think another potential problem is that even slightly plunging fire is going to be a real problem if you are relying on a high slope to deflect the shot.

Plus threats different from tank cannon fire, like top-attack EFP... May look at comparison of top protection of M1 compared with T-series. Highly angled steel plate is really compromise decision.
 
Plunging fire from 122mm HE or larger will go through as well I think.
 
Well, those would wreck most tanks anyway, difference wound be only between FU and FUBAR.
 
Do we have good estimates available for penetration of various impact fused HE rounds ?
Well, just out of my mind - 122mm could wreck 60mm plate(like IS-2 did with Panther turret side). That's not taking into account weld lines and whole set of outer equipment like sights.

 

But this is not so comparable to lower velocity plunging indirect fire.
 


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#42 GARGEAN

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Posted 18 March 2018 - 0615 AM


 

 

 

 

 

I think another potential problem is that even slightly plunging fire is going to be a real problem if you are relying on a high slope to deflect the shot.

Plus threats different from tank cannon fire, like top-attack EFP... May look at comparison of top protection of M1 compared with T-series. Highly angled steel plate is really compromise decision.
 
Plunging fire from 122mm HE or larger will go through as well I think.
 
Well, those would wreck most tanks anyway, difference wound be only between FU and FUBAR.
 
Do we have good estimates available for penetration of various impact fused HE rounds ?
Well, just out of my mind - 122mm could wreck 60mm plate(like IS-2 did with Panther turret side). That's not taking into account weld lines and whole set of outer equipment like sights.
 
But this is not so comparable to lower velocity plunging indirect fire.
 
Mostly. But big flat 2 inch thick roof with simple weld lines not too comparable with Panther turret side.
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#43 Interlinked

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Posted 18 March 2018 - 0647 AM

Well, just out of my mind - 122mm could wreck 60mm plate(like IS-2 did with Panther turret side). That's not taking into account weld lines and whole set of outer equipment like sights.

Depends on whether the shot was fired in fragmentation or delayed mode. In the delayed mode, 76mm HE-Frag can penetrate 30mm of armour at 1 km, and 85mm HE-Frag could penetrate 45mm at 30 degrees from 500 m and 50mm at 30 degrees from 300 m. I'm sure 122mm HE-Frag can penetrate even more than that, depending on the distance, but in the fragmentation mode, 122mm HE-Frag can't go through the roof armour of a T-64 turret. It can easily rip off hatches, sights and other important stuff and kill everyone inside, though, so it hardly matters.

https://1.bp.blogspo...mm+he+shell.jpg

Edited by Interlinked, 18 March 2018 - 0651 AM.

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#44 GARGEAN

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Posted 18 March 2018 - 0730 AM

Well, just out of my mind - 122mm could wreck 60mm plate(like IS-2 did with Panther turret side). That's not taking into account weld lines and whole set of outer equipment like sights.

Depends on whether the shot was fired in fragmentation or delayed mode. In the delayed mode, 76mm HE-Frag can penetrate 30mm of armour at 1 km, and 85mm HE-Frag could penetrate 45mm at 30 degrees from 500 m and 50mm at 30 degrees from 300 m. I'm sure 122mm HE-Frag can penetrate even more than that, depending on the distance, but in the fragmentation mode, 122mm HE-Frag can't go through the roof armour of a T-64 turret. It can easily rip off hatches, sights and other important stuff and kill everyone inside, though, so it hardly matters.

https://1.bp.blogspo...mm+he+shell.jpg
Yeah, that's kinda what I was talking about difference between FU and FUBAR.
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#45 KV7

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Posted 18 March 2018 - 0823 AM

What is 'killing everyone inside' - spalling ?

Even if we accept field artillery is going to be a big problem we are going to find marginal cases, for example you would like to be resistant to 81mm mortar rounds at least.


Edited by KV7, 18 March 2018 - 0827 AM.

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#46 GARGEAN

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Posted 18 March 2018 - 0826 AM

What is 'killing everyone inside' - spalling ?

Pressure bump after explosion breaking trough hatches.
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#47 Interlinked

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Posted 18 March 2018 - 0830 AM

What is 'killing everyone inside' - spalling ?

Even if we accept field artillery is going to be a big problem we are going to find marginal cases, for example you would like to be resistant to 81mm mortar rounds at least.

When the hatches of a tank are ripped off by the force of the explosion, the people under those hatches are probably dead.

I completely agree that protection from smaller artillery pieces is a very useful thing. I don't know if tanks were ever specifically designed with a requirement to be resistant to direct hits from 81mm mortars, but it seems that the thickness of roof plating needed to fulfill the universal requirement of 152/155mm airburst shrapnel resistance tends to coincide with that goal. Hatches and sights are usually proofed against machine gun fire as well so the damage from the fragmentation of a direct hit by an 81mm bomb is limited to some extent.

Edited by Interlinked, 18 March 2018 - 0838 AM.

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#48 KV7

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Posted 18 March 2018 - 2030 PM

Right, to go back to the original problem - if we have moderately sloped thick armor, a lot of plunging fire or top attack munitions will land onto armor designed to resist AT weapons from the frontal aspect without massive sloping - and therefore will have large LOS thickness from near vertical angles.

If we take say the T-72, the absolute size of the turret roof and exposed hull roof is not so large, and a direct plunging hit from say 122mm (or most top attack munitions) onto the glacis or turret cheeks is certainly going to be survivable. 


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#49 Adam Peter

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Posted 19 March 2018 - 1150 AM

When impacting at such a high angle, it is not the tip of the rod that penetrates the target but the tail.

 

Maybe there is some benefit for Soviet APFSDS for having larger fins (and speed drop on the other side) than contemporary NATO APFSDS?


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#50 Interlinked

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Posted 19 March 2018 - 1229 PM


When impacting at such a high angle, it is not the tip of the rod that penetrates the target but the tail.

 
Maybe there is some benefit for Soviet APFSDS for having larger fins (and speed drop on the other side) than contemporary NATO APFSDS?

It's totally negligible. According to the firing tables on Stefan Kotsch's website, the angle of impact of 3BM-15 at 2.0 km is only 0.13 degrees from the horizontal plane.

http://www.kotsch88....mm-ke-2A46M.htm
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#51 KV7

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Posted 19 March 2018 - 2038 PM

Things might get interesting if the fin impacts before the tip. But I know nothing about this.


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#52 GARGEAN

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Posted 20 March 2018 - 0112 AM

Considering relatively soft steel for fins and outer body plus pretty huge lever - fin with just be ripped off, adding minimal tilt to body.
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#53 KV7

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Posted 20 March 2018 - 0125 AM

Considering relatively soft steel for fins and outer body plus pretty huge lever - fin with just be ripped off, adding minimal tilt to body.

Yeah that was my guess.


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