122mm APBC Availability

[rexford]

Latest thoughts on subject is that 122mm APBC became available in limited quantities starting January 1945, and that 122mm AP was primary round through end of war. I believe that CMBB makes 122mm APBC the only armor piercing round starting August 1944, which may overstate effectiveness of 122mm ammunition.

[Redwolf]

Bad for the guy just attacking me

[Amedeo]

Hi Rexford!

Did you manage to obtain more data on the BR-471B DOI other than the ones posted a few weeks ago on the Tankers' Group forum?

BTW I noticed that the 152mm guns never switch to APBC in the game. Any info about the BR-540B DOI?

Bye,

Amedeo

[Karl_Smasher]

Originally posted by rexford:

Latest thoughts on subject is that 122mm APBC became available in limited quantities starting January 1945, and that 122mm AP was primary round through end of war. I believe that CMBB makes 122mm APBC the only armor piercing round starting August 1944, which may overstate effectiveness of 122mm ammunition.

What is the penetration of the 122mm AP compared to the APBC.

It now seems certain according to Svirin that the APBC was never actually used in front line combat apart from field trials and rare tests.

Heereswaffenamt august 1944 tests with JSII 122mm AP v Panther glacis, show it couldn't penetrate it at point blank range.

[rexford]

Originally posted by Karl_Smasher:

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

Latest thoughts on subject is that 122mm APBC became available in limited quantities starting January 1945, and that 122mm AP was primary round through end of war. I believe that CMBB makes 122mm APBC the only armor piercing round starting August 1944, which may overstate effectiveness of 122mm ammunition.

What is the penetration of the 122mm AP compared to the APBC.

It now seems certain according to Svirin that the APBC was never actually used in front line combat apart from field trials and rare tests.

Heereswaffenamt august 1944 tests with JSII 122mm AP v Panther glacis, show it couldn't penetrate it at point blank range.</font>

[rexford]

Originally posted by Karl_Smasher:

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

Latest thoughts on subject is that 122mm APBC became available in limited quantities starting January 1945, and that 122mm AP was primary round through end of war. I believe that CMBB makes 122mm APBC the only armor piercing round starting August 1944, which may overstate effectiveness of 122mm ammunition.

What is the penetration of the 122mm AP compared to the APBC.

It now seems certain according to Svirin that the APBC was never actually used in front line combat apart from field trials and rare tests.

Heereswaffenamt august 1944 tests with JSII 122mm AP v Panther glacis, show it couldn't penetrate it at point blank range.</font>

[Bastables]

Originally posted by rexford:

[

The information from Svirin that I saw on Tankers forum mentioned limited combat use starting January 1945. CMBB may overstate 122mm APBC availability by making it the primary round starting summer 1944.

Thanks. Lorrin[/QB]

Could you give us a link?

[TSword]

Rexford,

Very interesting !

Hopefully you also inform BTS on your findings !

Greets

Daniel

[rexford]

Originally posted by Bastables:

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

[

The information from Svirin that I saw on Tankers forum mentioned limited combat use starting January 1945. CMBB may overstate 122mm APBC availability by making it the primary round starting summer 1944.

Thanks. Lorrin

Could you give us a link?[/QB]</font>

[Bastables]

So APBC would be treated as equivalent to a "t" special round within the game? (1-2 rounds per IS II). Starting to appear in Jan '45?

Bugger joining Yahoo, sounds like work to me and an invitation to spam my already immolated hotmail account. Could you please perform a cut and paste job? It would be much appreciated.

[ November 04, 2002, 10:19 PM: Message edited by: Bastables ]

[rexford]

Muddying the waters some more, Miles Krogfus just posted on the Yahoo! Tankers site to effect that American and British compilation of Russian 100mm and 122mm ammo found in Berlin was all pointed nose. No APBC found.

Currently seeking more details on number of tanks and guns that contributed to ammo finds. Could be a few vehicles where APBC all used up, or wasn't available due to street fighting nature of combat (emphasis on HE). Or 122mm APBC limited use in general and not available to many guns and tanks.

[Guest Mike]

What was the substantive difference between the AP & APBC round then?

"BC" stands for Ballistic Cap IIRC, and is just a thin sheet with a better aerodynamic shape than the normal projectile. It shouldn't have any real effect on AP capability appart from lessining losss of velocity with range and perhaps giving a bit better accuracy.

Did hte Russians change the shape and/or material of the AP shot with hte APBC round viz the AP one?

[rexford]

Originally posted by Mike:

What was the substantive difference between the AP & APBC round then?

"BC" stands for Ballistic Cap IIRC, and is just a thin sheet with a better aerodynamic shape than the normal projectile. It shouldn't have any real effect on AP capability appart from lessining losss of velocity with range and perhaps giving a bit better accuracy.

Did hte Russians change the shape and/or material of the AP shot with hte APBC round viz the AP one?

Russian APBC has a flat nose and ballistic windscreen to reduce air resistance, AP is pointed nose and uncapped, loses velocity much faster than APBC.

122mm APBC penetrates 207mm at 0m and 0 degrees, 122mm AP defeats 174mm at same range and angle.

122mm APBC is superior against sloped armor since square nose digs in and counters ricochet forces, penetrating 82mm/55 degrees at 1750m. 122mm AP penetrates same armor at 100m.

Having a few 122mm APBC for use against Panthers drastically changes things.

[Guest Mike]

Originally posted by rexford:

Russian APBC has a flat nose and ballistic windscreen to reduce air resistance, AP is pointed nose and uncapped, loses velocity much faster than APBC.

122mm APBC penetrates 207mm at 0m and 0 degrees, 122mm AP defeats 174mm at same range and angle.

Presumably then the APBC had a higher velovity too - 'cos I'd certainly expect a pointed round to have better penetration than a blunt one at that range and angle??

122mm APBC is superior against sloped armor since square nose digs in and counters ricochet forces,

Yep - my point exactly.

[ November 10, 2002, 03:50 AM: Message edited by: Mike ]

[rexford]

Originally posted by Mike:

Originally posted by rexford:

</font><blockquote>quote:</font><hr />Russian APBC has a flat nose and ballistic windscreen to reduce air resistance, AP is pointed nose and uncapped, loses velocity much faster than APBC.

122mm APBC penetrates 207mm at 0m and 0 degrees, 122mm AP defeats 174mm at same range and angle.

Presumably then the APBC had a higher velovity too - 'cos I'd certainly expect a pointed round to have better penetration than a blunt one at that range and angle??

122mm APBC is superior against sloped armor since square nose digs in and counters ricochet forces,

Yep - my point exactly.</font>

[Guest Mike]

Ah - thanks, I didn't realise that.

Does this work at lower calibres too? The 76 (T34, Su-76) doesn't seem to get any great advantage from having a bunt nose - I thought the advantage of the blunt nose was vs sloped armour - allowing the shot to penetrate at closer to 90 deg than a pointed shot.

[Jeff Duquette]

Mike:

While blunt-nosed projectiles exhibited some advantages over ogival (pointy) projectiles these advantages were conditional. This wasn’t a super projectile. And contrary to what has been implied here in the past, Soviet blunt-nosed projectiles were originally developed to fight ships and later adopted for use against tanks. At the time of blunt-nosed projectile development neither of these two types of potential targets were equipped with armor that was particularly well sloped. Soviet Blunt nosed projectiles were originally developed to fight mildly sloping or non-sloping armor. In addition blunt nosed projectiles function well only when the armor being attacked is seriously overmatched…i.e. the projectile diameter is larger than the target armor is thick.

Regards

Jeff Duquette

[rexford]

Originally posted by Jeff Duquette:

Mike:

In addition blunt nosed projectiles function well only when the armor being attacked is seriously overmatched…i.e. the projectile diameter is larger than the target armor is thick.

Regards

Jeff Duquette

Jeff's last statement, about APBC only doing well against overmatched armor, is not correct. Actual firing test results disprove his assertion.

122mm APBC firing tests showed that the round did better and better against really thick armor as the impact velocity increased. The rate of penetration increase for a given increase (%) in velocity improved as impact velocity increased.

Above 2200 fps 122mm APBC penetration increases as velocity raised to 2.5 power, from 1800 to 2200 fps penetration increases as velocity raised to 1.8 power. The math disproves Jeff's point.

A 10% increase in velocity above 2200 fps buys 27% more penetration, at 2000 fps a 10% velocity increase buys 19% more penetration.

122mm APBC penetrates 207mm at 2600 fps impact, which is the opposite of the condition Jeff referred to.

When the impact velocity of flat nose APBC increases, the armor's ability to resist the tremendous impact imparted by the blunt shape appears to radically decrease.

There are limits here, such as when 57mm APBC strikes at 3000+ fps. 57mm APBC doesn't do very well for some reason.

[rexford]

Originally posted by Jeff Duquette:

Mike:

And contrary to what has been implied here in the past, Soviet blunt-nosed projectiles were originally developed to fight ships and later adopted for use against tanks

Regards

Jeff Duquette

Actually, Jeff's statement is not totally correct. When 122mm APBC proved effective against sloped tank armor it appears to have surprised the Russian tank designers.

122mm APBC was not necessarily developed to fight Panthers.

However, it is notable that SU 100 was originally intended to use APBC ammo and would have if production problems had not eliminated that option. The Russians appear to have known about the superior sloped armor effectiveness of APBC by the time SU 100 was being designed.

I never implied that APBC was developed to penetrate sloped German armor, and don't remember anyone else say something like that on this forum.

[Guest Mike]

Originally posted by rexford:

I never implied that APBC was developed to penetrate sloped German armor, and don't remember anyone else say something like that on this forum.

I didn't say you did!

I think I saw it on a web site somewhere, but it was a while ago now - in the days of the demo - or perhaps even before, when "we" considered it curious that the Sov's used blunt nosed AP ammo at all.

[Guest Mike]

The Russian battlefield has a section on the differentces - http://www.battlefield.ru/guns/defin_2.html#normaliz, and also see http://www.battlefield.ru/library/bookshelf/weapons/weapons10.html (about half way down the page), and also http://www.battlefield.ru/is2_1.html, next to teh drawings of the HE & AP projectiles half way down the page.

Plus there's limited discussion of it in http://www.battlefield.ru/is2_1.html

[Jeff Duquette]

Lorrin:

You really need to look into this a bit more deeply. Your letting your pride get in the way of presenting an unbiased assessment of APBC penetration capabilities. "Armor and Gunnery's" section on Soviet ordnance is based upon a fragile foundation. Now I would be happy to recomend both Russian and German source material that you should be trying to track down.

Regards

Jeff Duquette

[rexford]

Originally posted by Jeff Duquette:

Lorrin:

You really need to look into this a bit more deeply. Your letting your pride get in the way of presenting an unbiased assessment of APBC penetration capabilities. "Armor and Gunnery's" section on Soviet ordnance is based upon a fragile foundation. Now I would be happy to recomend both Russian and German source material that you should be trying to track down.

Regards

Jeff Duquette

Thank you for offer. Would like to see the list, at your convenience.

The book section you refer to is based on U.S. trials with 122mm APBC, Russian penetration test results during WW II (provided on Russian Battlefield site and by Vasiliy Fofanov), data in Woodman's book and analysis of all the data to see if it made sense and was consistent.

Recent posts on Tankers forum show that APBC estimates in our book for 122mm and 85mm rounds are consistent with Russian figures from WW II.

Our penetration data was applied to post-WW II Russian trials against captured American armor from Korea and worked fairly well. Firing tests with 100mm APBC captured during 1950's showed rounds penetrating less than we predicted, which could be due to lowered quality export ammo, or could be result of high impact velocity which diminished APBC performance.

The 76.2mm T34 APBC estimates we prepared look reasonable but have some troublesome aspects.

Our analysis of 57mm APBC penetration data from Russian sources, using all the data we have accumulated, suggested muzzle velocity was 871 m/s instead of the 990 m/s that is usually quoted. Mile Krogfus sent me an American penetration graph for Russian ammo at 30 degrees that listed 57mm L73 APBC muzzle velocity at 850 m/s (interesting, wouldn't you say).

While there is always room for improvement, and I am always going back over the Russian penetration figures and comparing them to combat results, our work seems to have many consistencies going for it. Fragile is not the correct word for the Russian penetration estimates, since the results have been tested many times.

It may be that further work will change some of the figures.

The biggest issue right now concerns Russian AP penetration stats, which limit 100mm and 122mm guns to very short effective ranges against 82mm/55 degree armor. Source references that might help verify what we have done to date, or suggest improvements, would be gratefully accepted.

Lorrin

[ November 12, 2002, 07:02 AM: Message edited by: rexford ]

[Ex Bellator]

Hi Rexford,

I don't want to sideline your interesting thread, but as the most knowledgable fellow around , can you please spare one post to help me with something which is bugging me with the T-34M41 series.

Dou you think it is reasonable that according to the armour thickness colour bars around the T34 picture in the toolbar, the weakest armour on the whole tank is on the front turret? It would seem that the T-34 is an awful design if they put the weakest point at the most likely place to be hit.

I have seen the numbers on the data page, and my gut feeling is that the 'Rounded' bonus is not working. I know the penetration capability of various smaller German AP rounds is being tweaked in a patch, but I wonder if they have approached the problem from the wrong end.

Many thanks

[Amedeo]

A couple words about the 'rounded' feature in CMBB.

If we assume a perfect hemicylindrical mantlet and a shot that arrives with a trajectory ortogonal to the flat 'back' of the half-cylinder, with the help of elementary trigonometry, one can find that half of the hits should strike the armour with an aspect of less than 30° while the other half should strike the mantlet at angles higher than 30°.

But, at a first glance, I think that the game models this differently.

Regards to all,

Amedeo