How to calculate HE penetration?

[flamingknives]

Were there HESH rounds in WWII?

No. Came soon after though.

To be effective, there has to be good contact between the HE and the armour, so as to better transmit the shockwaves.

[Mr. Tittles]

If you look at some of the numbers listed in the game as far as HE penetration, its probably just based on velocity. The game lists identical numbers for the panther gun and the soviet gun mounted on the marder. Both have velocitys close to 700m/s for HE. Both show 61mm penetration at 100 meters and 500 meters, which is strange. It does decrease at greater ranges.

The Panzer IV website does not list the angle on these penetration values. Anyone know if it is 60 degrees?

[Redwolf]

Originally posted by Mr. Tittles:

Both have velocitys close to 700m/s for HE. Both show 61mm penetration at 100 meters and 500 meters, which is strange. It does decrease at greater ranges.

It is probably assumed that anything faster than a given optimal speed causes the casing to desintegrate prematurely.

[Guest Mike]

I wonder if the explosion of a HE round actually degrades it's penetrative ability?

In an old "war monthly" I have there's a sequence of shots showing an SS-11 ATGM with a dummy warhead hitting the side of a Centurion - after the hit the tank is a mess - the tracks are broken, and the rubber wheels on fire - possibly from burning of residual fuel from the missile?

Obvioulsy the missile is a lot larget than your typical HE round, but it's also a lot slower, and that V^2 component can make a lot of difference to Ek!!

[Mr. Tittles]

Originally posted by redwolf:

</font><blockquote>quote:</font><hr />Originally posted by Mr. Tittles:

Both have velocitys close to 700m/s for HE. Both show 61mm penetration at 100 meters and 500 meters, which is strange. It does decrease at greater ranges.

It is probably assumed that anything faster than a given optimal speed causes the casing to desintegrate prematurely. </font>

[Mr. Tittles]

[ October 02, 2003, 01:13 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

Originally posted by Mike:

I wonder if the explosion of a HE round actually degrades it's penetrative ability?

Its probably a safe bet that the explosion must occur after the HE shell has started or finished penetrating. If the HE detonates before, it blows much of the mass of the shell away. It may actually help penetration if it occurs after the shell has penetrated into the armor close to its diameter width. The explosion would then be acting as a sort of booster.

It would be interesting to set up a 75mm HE shell against armor and find out what it can penetrate at no velocity whatsoever. It may be 5mm or less.

[Horncastle]

Originally posted by Mike:

I wonder if the explosion of a HE round actually degrades it's penetrative ability?

In an old "war monthly"

Bit off topic, but would you know anywhere where I could get some war monthly mags from. I used to have some that were given to me by my cousin when but a nipper, but threw them away. Do you know any sites that may have classifieds ads etc that might occasionally put them for sale. Or has someone set up a site with scans of articles in?

Cheers

[Redwolf]

Originally posted by Mike:

I wonder if the explosion of a HE round actually degrades it's penetrative ability?

In an old "war monthly" I have there's a sequence of shots showing an SS-11 ATGM with a dummy warhead hitting the side of a Centurion - after the hit the tank is a mess - the tracks are broken, and the rubber wheels on fire - possibly from burning of residual fuel from the missile?

Obvioulsy the missile is a lot larget than your typical HE round, but it's also a lot slower, and that V^2 component can make a lot of difference to Ek!!

You probably mean the AT-11, the ATGM fired from the T-90.

SS missiles are the big operational ones :eek:

An ATGM is actually pretty slow, I wonder whether they accidentially used a real warhead :cool:

[ October 02, 2003, 07:57 AM: Message edited by: redwolf ]

[Redwolf]

Originally posted by Mr. Tittles:

</font><blockquote>quote:</font><hr />Originally posted by redwolf:

</font><blockquote>quote:</font><hr />Originally posted by Mr. Tittles:

Both have velocitys close to 700m/s for HE. Both show 61mm penetration at 100 meters and 500 meters, which is strange. It does decrease at greater ranges.

It is probably assumed that anything faster than a given optimal speed causes the casing to desintegrate prematurely. </font>

[Sardaukar]

Originally posted by redwolf:

</font><blockquote>quote:</font><hr />Originally posted by Mike:

I wonder if the explosion of a HE round actually degrades it's penetrative ability?

In an old "war monthly" I have there's a sequence of shots showing an SS-11 ATGM with a dummy warhead hitting the side of a Centurion - after the hit the tank is a mess - the tracks are broken, and the rubber wheels on fire - possibly from burning of residual fuel from the missile?

Obvioulsy the missile is a lot larget than your typical HE round, but it's also a lot slower, and that V^2 component can make a lot of difference to Ek!!

You probably mean the AT-11, the ATGM fired from the T-90.

SS missiles are the big operational ones :eek:

An ATGM is actually pretty slow, I wonder whether they accidentially used a real warhead :cool: </font>

[Mr. Tittles]

Well there are two possible explanations:

1) The Tiger HE shell is robust enough to work normally up to its maximum speed.

2) Over time, we had quite some threads where CMBB showed the same penetration for whole row or several adjacent numbers in the penetration charts. Could be a bug, but BFC never commented. [/QB]

If HE fails, then its penetration would go down, not stay the same. There would be a HE gap of sorts.

A quick review of other weapons HE penetration makes me lean towards #2. For some reason, 61mm penetration shows up in multiple rows. I believe that the data shown in the info window might not reflect what is really going on as far as the games mechanics/algorithyms.

The more thought I give it, the more it seems there must have been a mechanism for delaying the percussion fuzing. That is, there must be a setting on the shell to delay the explosion. Indirect Artillery uses a time mechanism based on revolutions. So does antiaircraft flak shells, but this direct fire HE would be a delay based on contact. That is, once the percussion fuze is tripped, its train of firing could be immediate or perhaps variable or a fixed value.

A percussion fuzed HE shell that strikes armor and immediately explodes would have to rely primarily on the explosive to blast through the armor (well the front scab of the shell would help but much of the mass of the shell would leave the 1/2MV^2 equation).

AP rounds must have some sort of impact fuzing (if it has a HE charge). The sudden impulse of deceleration setting off a delay. This must all be in the rear of the AP round. another reason HE would be a poor 'AP' substitute is that it has a hole in its front! The contact fuze is made of soft materials and is screwed into the front of the HE shell.

A major factor is also how the HE shells are made. Are they cast? Forged? Drawn/stamped?

[ October 02, 2003, 10:46 AM: Message edited by: Mr. Tittles ]

[Mr. Tittles]

http://members.tripod.com/~nigelef/ammo.htm

This site claims the 17lbr high velocity HE round was made from stouter material than other HE rounds. I would assume that other HVHE would also have to be made of materials to withstand the stress of firing at similar velocities.

[flamingknives]

A major factor is also how the HE shells are made. Are they cast? Forged? Drawn/stamped?

Cast or Drawn would be the only ones that would work - cartridge cases are drawn, bullets are drawn and then... gah! I can't remember the correct term! Spun? Like saucepans.

If cast, the shells would have to then be turned to fit the gun barrel and in most cases would have a rough surface where it didn't contact the barrel.

Cast would be the most logical as drawing only really works for thin walled stuff (really thin, actually, thickness<5mm)

Turning the whole thing out of solid rod would be horrendously wasteful for HE shells.

[rexford]

Many HE shells can be set for instant detonation upon impact, or for a delay between impact and explosion.

Against infantry in the woods, instant detonation works best for hits high up against trees, where you want fragments to instantly rain down on infantry under or near trees.

For infantry in trenches, set HE for delay and fire at ground infront of trench so shell hits ground, bounces up in the air and explodes over the trench.

I assume anti-tank use of HE shells would set detonation to delay.

[rexford]

PzKpfw IV Universe site presents penetration against vertical armor.

[Mr. Tittles]

Anyone know what the delay is? Is it some fixed setting or a variable type thing?

[Guest Mike]

Originally posted by Sardaukar:

I think he means SS-11 ATGM, first generation wire guided anti-tank missile.

Yep - the magazine dates to the 70's - a bit before the T-90's time, and when the Centurion was still pretty much the best "Western" tank around.

[Claus B]

I cut this from a picture of a damaged Cromwell tank in Villers-Bocage (Taylor: Villers Bocage through the Lens). It shows the right hand side of the turret. It has been suggested that the damage is from a HE round, probably fired point-blank by an 8,8cm KwK 36 (Tiger gun).

Judging from the suggestions made in this topic, my interpretation would be that the HE round hit, penetrated the outer layer of 51mm IT80 armour by virtue of its velocity, but detonated in the process, leaving the 12,7mm IT110 inner armour plate intact.

Comments?

Claus B

[ October 03, 2003, 05:57 AM: Message edited by: Claus B ]

[flamingknives]

...the 17lbr high velocity...

Correct nomencleture is 17pdr. or 17pr.

Yep - the magazine dates to the 70's - a bit before the T-90's time, and when the Centurion was still pretty much the best "Western" tank around.

1966 saw the introduction of the Chieftain, rendering the Centurion and the Conqueror, which was a more powerful tank, obsolescent. They'd both still have been used for firing tests though.

[Redwolf]

Originally posted by Mr. Tittles:

Anyone know what the delay is? Is it some fixed setting or a variable type thing?

It is variable, at least on HE rounds for real artillery, like 105mm.

In the ETO US artillery units sometimes cleaned houses by setting the time for explosion after impact so that the rounds would penetrate from the roof down into the floor they wanted and exploded there. I don't have a primary source about it, but there was a thread on the CMBO forum about it which was convincing.

[ October 03, 2003, 07:59 AM: Message edited by: redwolf ]

[Mr. Tittles]

Originally posted by Claus B:

I cut this from a picture of a damaged Cromwell tank in Villers-Bocage (Taylor: Villers Bocage through the Lens). It shows the right hand side of the turret. It has been suggested that the damage is from a HE round, probably fired point-blank by an 8,8cm KwK 36 (Tiger gun).

Judging from the suggestions made in this topic, my interpretation would be that the HE round hit, penetrated the outer layer of 51mm IT80 armour by virtue of its velocity, but detonated in the process, leaving the 12,7mm IT110 inner armour plate intact.

Comments?

Claus B

I am not too familiar with the shape of these tanks but maybe someone can confirm:

1. Is there supposed to be a big rivet at about 11 0'clock from the center of the hit?

2. Does the outer armor appear to be buckled in somewhat?

It certainly appears to be a HE shell and not HEAT. From the blast area, It appears that it came from a flat trajectory. Is the outer armor not as hard as the inner armor?

I would concur that it appears that the HE went off after 'stalling' at the inner armor. Would be nice to know what internal effcts it had if any.

[Mr. Tittles]

http://www.panzerace.net/main/normandy.asp?page=3

This detailed account would suggest that it either came from a TigerI or perhaps a Panzer IV.

Interesting tidbit is that a line of Cromwells were unmanned when the panzerace made his rampage. Perhaps Whittman wanted to try HE on them?

[Redwolf]

Whoever shot the HE round probably ran out of AP.

If this is supposed to be Villers-Bocage you can safely assume that the initial single Tiger ran out of AP mid-battle.'

[rexford]

Originally posted by Mr. Tittles:

Anyone know what the delay is? Is it some fixed setting or a variable type thing?

Sherman tank 75mm HE can be set for 0.05 second delay, or superquick action with immediate detonation.

U.S. manual on Tank Gunnery states that "Superquick action when striking armor plate, a gun shield or a building will burst before it can penetrate."

"The 0.05 second delay action results in the shell penetrating before bursting when it strikes light armor, gun shields or buildings. If the shell strikes the ground, it ricochets, travels 20 to 25 yards beyond the point of impact, and then bursts about 10 feet in the air. Because of the downspray from the burst in tyhe air, a ricochet burst has devastating effect on personnel without overhead cover."