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About Ammunition...


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Blue_Badger #21 Posted 19 July 2013 - 10:49 AM

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It would appear that I overstated the effects of overpressure on modern combat vehicles. The second report you provided does still detail damaging effects caused by rapid compression of air but it is limited to burst eardrums and first degree burns.

I was basing my thoughts around WW2 combat reports which gave the impression that the rounds penetration caused the heat which detonated the ammo. Later ones (these were written in the Africa campaign) detail that it was in fact hot fragments. The fragments being heated through heat sear. The lethal effects of the rounds would also be compounded by poor crew protection. I was also thinking of several types of bunker busting ammunition. HESH, HE, MPAT and regular concrete training rounds. All of these (except the training rounds which are simply sited to be "effective") are sited to be able to eliminate the target through concussive overpressure. However the only one which translates to the situation in question is MPAT, which since been shown to be a rather poor bunker buster (troops survived inside regularly after a hit.) The others have the advantage of an explosive charge sending a large mass through at speed. I think this likely magnifies the effects some what.  

Heat sear is another phenomenon that is capable of causing extreme heat but I can't find anything solid. The most extreme effects have been documented by the royal Navy where it is said that rooms catch fire. In tank warfare, with smaller ammo and fewer flammable items I'm guessing that it is reduced in effect.

The Bradley incident is an interesting one. Not only did It pass clean through but there were no major pyrophoric effects. Given that the Bradley's side armour is only proofed against 14.5mm I'd say that what was observed was evidence against using that type of ammo on soft skinned targets. (Not that this disproves your point)

Thanks for your sources, they were a good read.

Vlevs #22 Posted 26 July 2013 - 11:17 AM

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View PostBlue_Badger, on 19 July 2013 - 10:49 AM, said:

It would appear that I overstated the effects of overpressure on modern combat vehicles. The second report you provided does still detail damaging effects caused by rapid compression of air but it is limited to burst eardrums and first degree burns.
I was basing my thoughts around WW2 combat reports which gave the impression that the rounds penetration caused the heat which detonated the ammo. Later ones (these were written in the Africa campaign) detail that it was in fact hot fragments. The fragments being heated through heat sear.
[...]
The Bradley incident is an interesting one. Not only did It pass clean through but there were no major pyrophoric effects. Given that the Bradley's side armour is only proofed against 14.5mm I'd say that what was observed was evidence against using that type of ammo on soft skinned targets. (Not that this disproves your point)
Vast majority of WW2 AP ammo carried bursting charge. I believe it's hard to differentiate effects of bursting charge vs heat sear by observing from afar. Of course, 2-pdrs don't have bursting charge so the point is valid. Still, there's a difference between a spark lighting up unprotected ammo vs all-encompassing furnace incinerating crew. As for comparing to HE shells for effect, HE shells produce overpressure effect far more effectively, and 105 mm HE shell's explosive energy is roughly twice that of a modern APFSDS penetrator muzzle energy.
Since APDS doesn't carry bursting charge, after-armor effect is comparatively limited, and relies solely on kinetic energy transforming into fragments and heat. And it's important to consider that despite huge speeds, modern penetrators don't have overwhelming amounts of energy vs those used in WW2 (quick and dirty calculation gives 6,6 MJ for top-of-the-line 120 mm APFSDS vs 5,2 MJ for 88 mm KwK 43). In addition, when hitting a modern tank, much of that energy is spent on making a hole in the armor.
In addition, there's oft-repeated claim that in WW2 battles of Pacific American tanks were better off using HE, as Japanese light tanks could go on after being perforated by 75 mm AP, as light armor did not trip bursting charge. Further suggesting, that heat sear and overpressure inside tank aren't the killers that they're made out to be. This seems analoguous to how lightly armored Bradley doesn't seem to break the penetrator enough to get substantial pyrophoric effect.

View PostBlue_Badger, on 19 July 2013 - 10:49 AM, said:

The most extreme effects have been documented by the royal Navy where it is said that rooms catch fire. In tank warfare, with smaller ammo and fewer flammable items I'm guessing that it is reduced in effect.
That's interesting. Can you detail this incident a bit more? But being navy, there's a bit difference in scale, and battleship shells outmass tank shells by a factor of 100 or so.

Edited by Vlevs, 29 July 2013 - 03:53 PM.


Blue_Badger #23 Posted 05 August 2013 - 09:04 PM

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I read the info about heat sear in a book several years ago. It was about the battle of Jutland and why it went wrong. I don't remember any of the finer details as I didn't even take the book out, I just read it there lol.

Basically the British conducted several investigations after the battle to find the source of error. the overstocking of the charges in the turret bustles and outside the magazines was a popular theory but simple sparks and the expected heat from the penetration (heat sear was not a rated factor then). The tests showed the round and armour where it passed through super heating, almost to melting point, due to the extreme friction. Quite deadly as you can imagine.

Vlevs #24 Posted 16 August 2013 - 09:39 PM

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View PostBlue_Badger, on 05 August 2013 - 09:04 PM, said:

The tests showed the round and armour where it passed through super heating, almost to melting point, due to the extreme friction. Quite deadly as you can imagine.

Quite interesting, I know very little of naval side of things. And that's where much of the old knowledge about shells vs armor is.

Whether sparks in melting point are deadly depends entirely of what mass is a human exposed to. What I've read about penetration incidents tells me, that while burns were a common injury among tank crew members, they were very rarely lethal when they weren't from fuel or ammo fire. So in this case I'm not really satisfied with "imagining" what danger they present, I want some actual recorded incidents. And so far it seems that indirect hits from non-bursting shells are generally not life-threatening.

jaskap77 #25 Posted 28 September 2013 - 09:49 PM

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View PostAIM_120_AMRAAM, on 28 April 2013 - 01:39 PM, said:

So yeah, basically I got some questions about various types of Ammunition used in WW II and later-on (Captain Obvious, duh!)



1. Why did the Russian 122mm guns have 2-piece Ammunition? I only know seperated shells and shell propellants from high-caliber artillery pieces starting in the 152mm range? For example, it seems logical to me, that the 152mm SU/ISU-152 gun was using 2-piece Ammunition because of the weight and size of the shell to enable the Crew to handle it.

While I know that the comparison is off because of the large time difference, a shell I saw and handled in the Tank Museum in Munster (Leopard 2 APDSFS 120mm Shell I believe) weighted slightly less than 20 Kg. I always thought that 2-piece Ammunition was used because of the shell weight with increasing caliber (modern Panzerhaubitze 155mm HE-Shell weighs in at around 80 Kg for the whole cartridge).

Wouldn't it make more sense to use "complete" cartridges in the 122mm gun in order to increase its Rate of Fire? Didn't Soviet Tanks provide enough space to store the cartridges in one piece in the tank?



2. My next question is about rifled guns and HEAT-Ammo. I read somewhere that a HEAT-Shell is less effective when fired from a rifled gun because of the spin imposed on the Shell. The rotation would hinder the creation of the destructive "Metal Spike" and therefore lessening its effectiveness against hardened targets.

How was this counter-acted by tank designers? Since most tanks still used rifled guns after the war (like the Leopard 1) wouldn't it be kinda useless to design a powerful HEAT-Shell only for its effectiveness to be decreased by the very nature of the gun?



For these questions few thoughts.

1. Cartridge type ammo is typically longer (assembled) than cartouche shot. And to my knowledge there wasn't technology available to make durable disintergating casings as in modern MBT's. And soviet tanks have allways been smaller in size. So I bet this (lack of space) is reason for two piece ammo.

2. As mentioned earlier, rotation reduces copper cone formation thus reducing penetration. One way to counter act rifling is to make ammunition with rotating groove band (part that mates with barrel rifling)




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