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This is whole chart is strange... 360-370 should be M774... M833 should definitely penetrate more than 400mm.  430-440 (where M900 is on the chart) is more believable for it. Armor values are also off. "T-62 basic" looks like a T-62M with metal-polymer blocks. T-72A and M1 should have the exact same protection...

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1 hour ago, heretic88 said:

This is whole chart is strange... 360-370 should be M774... M833 should definitely penetrate more than 400mm.  430-440 (where M900 is on the chart) is more believable for it. Armor values are also off. "T-62 basic" looks like a T-62M with metal-polymer blocks. T-72A and M1 should have the exact same protection...

 

The chart is correct. The labeling might be a bit confusing: the T-72M1 referenced in the table is not the basic T-72M1 (i.e. Object 172M-1-E5 or Object 172M-1-E6) but rather the T-72M1M (Object 172M-1-E7),  which is a T-72M1 with the more advanced NERA armor of the T-72B. Later this was export variant was superseded by the T-72S (Object 172M-1-E8) as true export model of the T-72B. At least on T-72M1M tank was operated by the Republic Guard in Iraq. Rheinmetall marketed its 105 mm smoothbore guns as capable of defeating the T-72M1M (aswell as the T-72S and T-72B), which the normal 105 mm rifled guns L7 and M68 were incapable of doing. They tried to persuade the US Army to buy smoothbore guns for the Stryker MGS among others.

Due to its rarity, the existence of the T-72M1M remained unknown for some while and I haven't seen any clear data to whom exactly how many T-72M1M tanks were sold.

 

I don't think that the "basic" belongs to the T-62 version, but rather is meant to show that this is the basic threat for which the mentioned APFSDS ammunition was adopted. The values clearly reflects the T-62M.

 

As for the penetration achieved by the M833 APFSDS: 400 mm against steel armor at normal combat ranges is not possible. The length and velocity of the longord penetrator are not enough to achieve such levels of performance. I.e. the M833 has a 427 mm long penetrator, as you can see in the following images:

clip1543.pngIOLKSbN.png

 

The following graph taken from a declassified document shows the reduction of the velocity of several APFSDS types over ranges. As one can see, the impact velocity of the M833 APFSDS at 2,000 metres (typical combat range used to measure armor penetration) will be slightly below 1,400 m/s.

03iJE1f.png

The following charts shows a comparison of different methods for measuring normalized penetration (i.e. LOS penetration against a sloped target) in relation to the length of the high-density longrod penetrator of an APFSDS round. It compares two mathematical solutions (the forumula from W. Lanz & W. Odermatt aswell as a sub-module of the ALEGRA software suite) with actual measurements (the dots) which are interpolated using a polynomial fit (spline interpolation).

Looking at the chart, the length and velocity of the M833 would roughly result in a factor slightly below 0.8 penetrated steel thickness per penetrator length (P/L). A value of 0.8 multiplied with 427 mm will result in an estimated armor penetration 341 mm. Keeping in mind that the graph below is calculated for tungsten rods, the DU penetrator might (based on the exact criteria) perform better; the US Army Research Laboratory (ARL) has established that there is no difference in armor perforation (punching a hole through a steel target), but a difference for armor penetration (punching a hole into a steel target without fully perforating it) - so it isn't really clear wether this matters. Earlier work from ARL suggested a 8-10% lower penetration for tungsten rods, which would suggest 360-370 mm penetration (or rather 180-190 mm sloped at 60°) at 2,000 m distance. 

KO4RD6X.jpg

 

 

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Thanks for the explanation!

 

So, what do you think where does the 500mm for the M833 (in Militarysta's chart, and also in some russian sources) comes from? And what criterias did they use to determine such result?

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18 hours ago, heretic88 said:

Thanks for the explanation!

 

So, what do you think where does the 500mm for the M833 (in Militarysta's chart, and also in some russian sources) comes from? And what criterias did they use to determine such result?

No idea, most of them are taken from Bauman book (2006 Moscow) and they are put ther based on "unkown" criteria. Thats the problem whit, in theory realible sources.

Whit polish WITU is the same - sometimes they put something shamefully mistaken but generally it's good source.

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1 hour ago, Militarysta said:

No idea, most of them are taken from Bauman book (2006 Moscow) and they are put ther based on "unkown" criteria. Thats the problem whit, in theory realible sources.

Whit polish WITU is the same - sometimes they put something shamefully mistaken but generally it's good source.

What if they just made some typo? Maybe that data is for the M900 and for some reason they wrote M833 instead?

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On 8/11/2018 at 6:07 PM, SH_MM said:

IMml2ddeOiU.jpg

 

M833 - 360-370 mm

 

2 things: 

 

1. Source? 

 

2. Is this chart suggesting that M900 is only as powerful as M111 Hetz? Cause M111 could penetrate the T-72 at range (just barely), but the graph also shows M900 just barely penetrating a T-72 at range. 

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4 hours ago, Militarysta said:

How about DM13 and DM23? 

 

Based on the graphs you posted earlier, the 120 mm DM13 and 120 mm DM23 APFSDS have rather short penetrators, but also a rather large diameter. This is relevant, since penetration increases with diameter for a given length (more accelerated mass = more kinetic energy; penetration scales with kinetic energy). A slightly thinner rod with greater length would overall be superior, but technology and/or other requirements resulted in a diameter of 32 mm for the DM23 APFSDS (thinner tungsten rod with the available alloys did shatter too often).

YDhaJIw.jpg

 

The velocity of the DM23 after traveling 2,000 m is 1,529 m/s according to Swiss firing tables, but these list the muzzle velocity at only 1,640 m/s. So either the DM23 has a muzzle velocity of 1,640 m/s rather than the usually reported 1,650 m/s or the differences are caused by the Swiss measuring methology or are result of a local modification to the 12 cm PzKan 87 (Swiss designation for the DM23). If the latter cases are true, the impact velocity should be ~1,539 m/s instead.

Given that the penetration efficiency of shorter, thicker rods is more, it seems that the DM23 might achieve a penetration per length of above 1 against German HzB A steel:

Hqsv5rJ.jpg

(from Anderson and Riegel III, 28th International Symposium on Ballistics, "Estimate of penetration/perforation performance based on semi-infinite penetration data")

 

The problem is that exact informations regarding the specific steel alloy are rather scarce. HzB. A (and other steels of the HzB classification) existed in several versions with different alloys and hardness levels. In so far it is hard to convert the exact penetration data into RHA penetration. For the graph from the previous post, the steel hardness was said to be 255 on the Brinell scale.

 

Based on the plotted data, the DM23 might achieve between ~ up to 1.05 P/L, so its 360 mm long penetrator would result in a penetration of 378 mm into semi-infinite HzB. A steel. I don't have access to the source from which the data is taken (research paper by Hohler and Stilp, who apparently work for the German Fraunhofer institute), so it is unknown to me wether the steel target was sloped or not. The penetration against sloped targets would be higher than unsloped ones. As this is semi-infinite penetration, the perforation should be higher (meaning: DM23 would probably punch a hole through a 390 mm thick  HzB. A steel plate under the same conditions).

 

 

As for the 120 mm DM13: It is hard to say due to its unconventional construction. The BM-42 Mango APFSDS (which seems to be the closest thing in terms of internal penetrator construction) supposedly achieves a penetration slightly greater than the combined tungsten penetrator length; it has a higher muzzle velocity, but due to the fin construction a greater V-drop (Fofanov lists V-drop of Soviet 125 mm APFSDS ammo as between 60 and 140 m/s/km; given that Mango has full calibre fins, it should be significantly more than 60 m/s/km). Maybe the steel sheat helps increasing the penetration efficiency by simulating a thicker rod/lower L/D ratio?

 

The DM13 should have slightly above 1,500 m/s velocity at 2,000 m distance according to the US graph from the last post (probably 1,510 - 1,520 m/s). That and its shorter rod should lead to a lower penetratioon than DM23 by quite a bit... how much? I don't know. Maybe it is 320-350 mm, if the steel has any positive effect on armor penetration. Otherwise it would again be close to a P/L of 1 (if DM13 behaves like a conventional monoblock penetrator), which would lead to a penetration of only ~310-320 mm. Perforation and penetration against sloped targets might again be higher.

 

The penetrators of both the M833 and the 120 mm DM23 APFSDS have rounded tips, which performs slightly worse than flat-tipped penetrators against sloped target (but penetration still should be higher than against unsloped ones). 

120mm_DM23.jpg

 

1 hour ago, Lord_James said:

1. Source?  

 

2. Is this chart suggesting that M900 is only as powerful as M111 Hetz? Cause M111 could penetrate the T-72 at range (just barely), but the graph also shows M900 just barely penetrating a T-72 at range. 

 

Source is a Rheinmetall presentation from 2002. It used to be on DTIC, but I cannot find the full presentation at the moment... maybe the link expired or it was removed...

 

The M111 Hetz was capable of penetrating the original T-72's hull armor at very short ranges (some sources say 500-800 metres maximum). The T-72 had a glacis consisting of 80 mm steel, 105 mm stekoplastika (glass-fibre reinforced plastic) and 20 mm steel sloped at 68°. The T-72A had a different layout: 60 mm steel - 105 mm stekoplastika  - 50 mm steel (this is also 10 mm more steel), which was more effective against AP(FS)DS ammo. On later models, a 16 mm thick steel plate was added to the hull, improving protection further. The late production model of the T-72A featured spaced hull armor.

DGVZdcU.png

 

The M111 Hetz could never defeat the turret armor except for maybe a direct hit near the gun mount, where the armor thickness was only ~300-350 mm. The turret reaches a thickness of more than 475 mm at the well armored cheeks.

1451427730-t-72-ural-turret-thicknesss-c

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9 minutes ago, LoooSeR said:

Small Grammar nazi (or Grammar commisar?) note - not stekloplastika, but stekloplastik. 

 

I am innocent, S. Zaloga used the false form in "M1 Abrams vs T-72 Ural".

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12 minutes ago, SH_MM said:

I am innocent, S. Zaloga used the false form in "M1 Abrams vs T-72 Ural".

lol, i think that fiberglass layer is called Steklotekstolit (STB).

   Kind of terrible (for our tankers) thing is that T-72B3 still have unmodified armor from whatever T-72 they took for modernisation. I even saw T-72A (?) in one of TV reports about army training in the field. Strange to see that after so many years info on armor of Soviet tanks is still partially relevant.

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16 hours ago, SH_MM said:

 

Based on the graphs you posted earlier, the 120 mm DM13 and 120 mm DM23 APFSDS have rather short penetrators, but also a rather large diameter. This is relevant, since penetration increases with diameter for a given length (more accelerated mass = more kinetic energy; penetration scales with kinetic energy). A slightly thinner rod with greater length would overall be superior, but technology and/or other requirements resulted in a diameter of 32 mm for the DM23 APFSDS (thinner tungsten rod with the available alloys did shatter too often).

YDhaJIw.jpg

 

The velocity of the DM23 after traveling 2,000 m is 1,529 m/s according to Swiss firing tables, but these list the muzzle velocity at only 1,640 m/s. So either the DM23 has a muzzle velocity of 1,640 m/s rather than the usually reported 1,650 m/s or the differences are caused by the Swiss measuring methology or are result of a local modification to the 12 cm PzKan 87 (Swiss designation for the DM23). If the latter cases are true, the impact velocity should be ~1,539 m/s instead.

Given that the penetration efficiency of shorter, thicker rods is more, it seems that the DM23 might achieve a penetration per length of above 1 against German HzB A steel:

Hqsv5rJ.jpg

(from Anderson and Riegel III, 28th International Symposium on Ballistics, "Estimate of penetration/perforation performance based on semi-infinite penetration data")

 

The problem is that exact informations regarding the specific steel alloy are rather scarce. HzB. A (and other steels of the HzB classification) existed in several versions with different alloys and hardness levels. In so far it is hard to convert the exact penetration data into RHA penetration. For the graph from the previous post, the steel hardness was said to be 255 on the Brinell scale.

 

Based on the plotted data, the DM23 might achieve between ~ up to 1.05 P/L, so its 360 mm long penetrator would result in a penetration of 378 mm into semi-infinite HzB. A steel. I don't have access to the source from which the data is taken (research paper by Hohler and Stilp, who apparently work for the German Fraunhofer institute), so it is unknown to me wether the steel target was sloped or not. The penetration against sloped targets would be higher than unsloped ones. As this is semi-infinite penetration, the perforation should be higher (meaning: DM23 would probably punch a hole through a 390 mm thick  HzB. A steel plate under the same conditions).

 

 

As for the 120 mm DM13: It is hard to say due to its unconventional construction. The BM-42 Mango APFSDS (which seems to be the closest thing in terms of internal penetrator construction) supposedly achieves a penetration slightly greater than the combined tungsten penetrator length; it has a higher muzzle velocity, but due to the fin construction a greater V-drop (Fofanov lists V-drop of Soviet 125 mm APFSDS ammo as between 60 and 140 m/s/km; given that Mango has full calibre fins, it should be significantly more than 60 m/s/km). Maybe the steel sheat helps increasing the penetration efficiency by simulating a thicker rod/lower L/D ratio?

 

The DM13 should have slightly above 1,500 m/s velocity at 2,000 m distance according to the US graph from the last post (probably 1,510 - 1,520 m/s). That and its shorter rod should lead to a lower penetratioon than DM23 by quite a bit... how much? I don't know. Maybe it is 320-350 mm, if the steel has any positive effect on armor penetration. Otherwise it would again be close to a P/L of 1 (if DM13 behaves like a conventional monoblock penetrator), which would lead to a penetration of only ~310-320 mm. Perforation and penetration against sloped targets might again be higher.

 

The penetrators of both the M833 and the 120 mm DM23 APFSDS have rounded tips, which performs slightly worse than flat-tipped penetrators against sloped target (but penetration still should be higher than against unsloped ones). 

120mm_DM23.jpg

 

 

Source is a Rheinmetall presentation from 2002. It used to be on DTIC, but I cannot find the full presentation at the moment... maybe the link expired or it was removed...

 

The M111 Hetz was capable of penetrating the original T-72's hull armor at very short ranges (some sources say 500-800 metres maximum). The T-72 had a glacis consisting of 80 mm steel, 105 mm stekoplastika (glass-fibre reinforced plastic) and 20 mm steel sloped at 68°. The T-72A had a different layout: 60 mm steel - 105 mm stekoplastika  - 50 mm steel (this is also 10 mm more steel), which was more effective against AP(FS)DS ammo. On later models, a 16 mm thick steel plate was added to the hull, improving protection further. The late production model of the T-72A featured spaced hull armor.

DGVZdcU.png

 

The M111 Hetz could never defeat the turret armor except for maybe a direct hit near the gun mount, where the armor thickness was only ~300-350 mm. The turret reaches a thickness of more than 475 mm at the well armored cheeks.

1451427730-t-72-ural-turret-thicknesss-c

Lol M111 penetrating glacis T-72A(60 mm steel+105 mm stekloplastik+50 mm steel) at distance 1500-2000 m( ОКР Отражение). 

only after welding a 16 mm high hardness plate could protect the T-72A from M111 at an impact speed of 1428 m / s

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