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18 hours ago, Scav said:

IIRC XM827 was supposed to be DU which at this point was probably superior due to alloys being better, might explain the difference?

 

The there were tungsten and DU versions of the XM827 during development, but the DU version was prefered in the end (still canceled in favor for the M829 though). Likewise the US Army tested WHA and DU versions of the XM833. The article from the ARMOR magazine doesn't mention any materials, but it also includes one mention of the M735A1 (with DU penetrator).

 

At the time, DU alloys could probably achieve better performance, but the 120 mm DM13 should be better than the M735 APFSDS and its M735A1 sub-variant, simply based on physics.

 

18 hours ago, Scav said:

Could you potentially give a link or something?

 

It is availabe on the website of the German patent office, the European patent office, Google patents and many more

 

https://worldwide.espacenet.com/publicationDetails/biblio?CC=DE&NR=2234219C1&KC=C1&FT=D#

 

18 hours ago, Scav said:

95% tungsten seems on the low end, would explain why they thought a more complex shape was necessary...

 

Actually it seems that modern tungsten heavy alloy penetrators are usually made with a slightly smaller tungsten content, in some cases as low as 90%. This way it is possible to create alloys with more ductility and/or strength.

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14 minutes ago, SH_MM said:

The there were tungsten and DU versions of the XM827 during development, but the DU version was prefered in the end (still canceled in favor for the M829 though). Likewise the US Army tested WHA and DU versions of the XM833. The article from the ARMOR magazine doesn't mention any materials, but it also includes one mention of the M735A1 (with DU penetrator).

 

At the time, DU alloys could probably achieve better performance, but the 120 mm DM13 should be better than the M735 APFSDS and its M735A1 sub-variant, simply based on physics.

Yeah, in that paper where they discuss the advantages of DU vs tungsten they include performance of DU and WHA XM774 and XM833 IIRC.

https://www.alternatewars.com/WW3/WW3_Documents/Military_Tech/TAS_107/Tank_Ammo_Sec_107_JUN-1980.pdf
Pg22

 

21 minutes ago, SH_MM said:

It is availabe on the website of the German patent office, the European patent office, Google patents and many more

Thanks!
I was hoping for some penetration or atleast % numbers of efficiency but I guess that was asking too much :/.

Still, good find!

 

48 minutes ago, SH_MM said:

Actually it seems that modern tungsten heavy alloy penetrators are usually made with a slightly smaller tungsten content, in some cases as low as 90%. This way it is possible to create alloys with more ductility and/or strength.

Huh, interesting, though such a thing is stated in the document I mentioned above, I just haven't seen any alloy specifics on the more modern penetrators.

Would a jacketed tungsten rod not partially solve the issue by using a steel jacket?

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1596568117_Challenger2vsM1A2.thumb.jpg.f

 

This is a snipplet from "Challenger 2 Main Battle Tank Owners' Workshop Manual: 1998 to Present" by Lt. Col. Dick Taylor of the RTR.

 

Apparently the M1A1 HA's DU armor results in about 15% better protection against APFSDS ammunition compared to the Challenger 2, but offers a lot lower protection against HEAT munitions. Given that the M1A1 HA's turret appears to have approximately 600-660 mm vs KE (estimated 30° arc and direct from the front), that would put the Challenger 2 at 510-560 mm vs KE (this figures would match the earlier documents form the Challenger 2 design phase asking for 500 mm vs KE on turret and hull). The Challenger 1 was designed to reach a protection level of 500 mm vs KE on turret and 275 mm vs KE on the upper hull front, but according to a footnote in the same book reached only 480 mm vs KE on the turret and 340 mm vs KE on the hull.

The Leopard 2 was apparently not only offered with the B armor configuration (as tested in the UK), but it was at least proposed with the C and D armor generations aswell (protection level of the latter armor type not being disclosed to the UK). It seems that the text on the right mentions protection figures in milimeters for the Leopard 2A4 with Type B and Type C armor configurations, but that is unfortunately cut off. The Leopard 2A4 (with Type B armor) was rejected for its poor armor, worse than the Chieftain with Stillbrew vs KE.

 

Does anybody have this book? I wonder if it is worth the read, because other snipplets I've seen seem to feature quite a lot of bias (i.e. tests of Challenger 2E in Greece).

 

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6 hours ago, SH_MM said:

Does anybody have this book? I wonder if it is worth the read, because other snipplets I've seen seem to feature quite a lot of bias (i.e. tests of Challenger 2E in Greece).

 

Good but not exceptional, the work is somewhat uneven, providing good details on the Omani Challenger 2 but very few about the engine and the ammunition, for example.

 

It's complementary to the book of Simon Dunstan.

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18 hours ago, SH_MM said:

1596568117_Challenger2vsM1A2.thumb.jpg.f

 

This is a snipplet from "Challenger 2 Main Battle Tank Owners' Workshop Manual: 1998 to Present" by Lt. Col. Dick Taylor of the RTR.

 

Apparently the M1A1 HA's DU armor results in about 15% better protection against APFSDS ammunition compared to the Challenger 2, but offers a lot lower protection against HEAT munitions. Given that the M1A1 HA's turret appears to have approximately 600-660 mm vs KE (estimated 30° arc and direct from the front), that would put the Challenger 2 at 510-560 mm vs KE (this figures would match the earlier documents form the Challenger 2 design phase asking for 500 mm vs KE on turret and hull). The Challenger 1 was designed to reach a protection level of 500 mm vs KE on turret and 275 mm vs KE on the upper hull front, but according to a footnote in the same book reached only 480 mm vs KE on the turret and 340 mm vs KE on the hull.

The Leopard 2 was apparently not only offered with the B armor configuration (as tested in the UK), but it was at least proposed with the C and D armor generations aswell (protection level of the latter armor type not being disclosed to the UK). It seems that the text on the right mentions protection figures in milimeters for the Leopard 2A4 with Type B and Type C armor configurations, but that is unfortunately cut off. The Leopard 2A4 (with Type B armor) was rejected for its poor armor, worse than the Chieftain with Stillbrew vs KE.

 

Does anybody have this book? I wonder if it is worth the read, because other snipplets I've seen seem to feature quite a lot of bias (i.e. tests of Challenger 2E in Greece).

 

according to most reliable sources M1A1HA / M1A2 have a protection of 600 mm in the frontal arc of 60 degrees.

this means that Challenger 1 and 2 has a protection of ~ 500 mm in a 60 ° frotal arc.

 

480 mm is if I correctly understood the speech about protection for special armor, which experienced for Challenger 1. But about the glacis a lot of questions. 275 mm probably without special armor. Ie just some steel plates. 340 mm probably with the "Light" Chebham version.

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1 hour ago, Clan_Ghost_Bear said:

What was the British rationale for not liking the ammo storage in the turret?

 

The Brits way the Brits modeled things, any non-kinetic parts of ammo that are hit are likely to kaboom and take out the machine, and so ignoring the fact that the ammo is separated in an armored compartment, ignoring that in frontal hits that the rear of the turret is the hardest thing to penetrate in a tank (as you have to punch through the *entire* turret) the Brits said that hull-bottom stowage for live ammo segments has the least chance of being hit. This is technically true comparing the amount of frontal area in which it is theoretically possible to hit the ammo, but this is ignoring the facts that the hull is less armored & that they can't separate off the ammo storage behind bulkheads with their stowage arrangement.

 

Due to the ammo separation it's virtually impossible to K-kill an Abrams by hitting the ammo, while a Chally 2 was K-killed when a friendly HESH shell hit an open hatch... and the blast detonated the hull ammo stowage.

 

TL;DR - The Brits judged purely by amount of frontal area ammo is stowed in, irrespective of how armored or safe that area is. By that logic, T-72s have the safest ammo stowage of any modern tank...

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On 11/27/2018 at 1:23 PM, SH_MM said:

The Challenger 1 was designed to reach a protection level of 500 mm vs KE on turret and 275 mm vs KE on the upper hull front, but according to a footnote in the same book reached only 480 mm vs KE on the turret and 340 mm vs KE on the hull.

Well, yes and no.

Spoiler

Afbeeldingsresultaat voor Challenger 1 protection

Challenger 1 in this case refers to the Challenger 1 and not Challenger 1 Mk 1 as a lot of people seem to think.

They say it's only able to stop T-72 tank rounds at ranges above 1km, now they supposedly rated the 125mm at 460mm DU and later in 1981 they rated the tungsten 125mm at 475mm.

Spoiler

pasted%20image%200%20(4)_a0ca159c91df075

I do have to point out how this table seems quite inaccurate or atleast inconsistent, even if it just refers to the hull armour, both the T-64 and T-72 reach higher than 270-290mm.

 

So, personally I'd put the turret more at around 470mm or so and the hull at 325 against WP ammo, against long rods.... it's going to be less than this.
 

On 11/27/2018 at 1:23 PM, SH_MM said:

The Leopard 2A4 (with Type B armor) was rejected for its poor armor, worse than the Chieftain with Stillbrew vs KE.

I've noticed that as well, they for some reason think the 2A4 was poorer armoured than the stillbrew chieftain, something I find quite funny.
The hull is obviously superior on the leo 2 and the turret especially in the frontal 60° is also superior or at the very least equal.
 

According to this page:

Spoiler

Image result for throw of the dice by stéphane mallarmé,accompanied by separate sheet with translation by anthony hartley, plate 12 in the portfolio shaped poetry (san francisco: arion press, 1981)

The stillbrew package in 1985 only managed to resist L23A1 (I assume it's L23A1, L23 is also possible) only at 1km, penetration for L23A1 according to another book (maybe the same one, but I think it's about the Challenger 1) is around 460mm.

So, ~450mm of KE protection at the tested spots isn't far off let alone superior to the 2A4's ~430mm which was achieved by firing what looks to be DM53 at it.

Spoiler

xNAFPmz.jpg

Right hand one was used for turret testing according to that slide and it looks an awful lot like DM53, the left one looks like DM33.

 

So, considering L23A1 is notably worse than DM53, I think it's safe to say it would  do worse against a 2A4 turret than DM53 and the protection given by the armour would "increase" as a result.
 

All of that is from a stricly frontal attack, the sides of a 2A4 are also fitted with spaced armour and the LOS of it would reach around 620-640mm if hit at a 30° angle.

The Stillbrew chieftain on the other hand ranges from ~160mm at the front corners to ~86mm at the flat turret sides, neither of these seem really better than what the 2A4 has to offer.

 

I also have to point out that it seems the Brits didn't realise that long rods actually perform better at angles than against flat armour, so to the left of the gun (from our POV) is only 120mm cast + ~60mm rubber + 125mm steel at 60°, which against a long rod won't perform as well as the right side which is 150mm cast + 60mm rubber + 150-215mm steel.

So in effect, the left side of the turret is quite a bit weaker than the right hand side despite probably having similar LOS values.

That's also why I consider the statement in the outer right column of that picture to be quite naive:
Reposted image for easier reading:

Spoiler

yOmGVG3.jpg

Quote

With it varying from 480mm to 540mm; however the final design was considered sufficient to stand a good chance of resisting the Soviet successor 125mm round (tungsten monobloc and sheathed staballoy, which was postulated as being able to penetrate around 530mm point blank).

So, despite their own round already penetrating it from 1km or so and the protection being quite inconsistent, they think it'll stop future 125mm long rod ammo?

L23A1 is already a little bit worse than 120mm DM23 in terms of raw performance, 3BM32 and 3BM42 I highly doubt will have any issue with this armour at most combat ranges.

So either they didn't think the Soviets couldn't make better ammo than they did, or they didn't understand that long rods perform better against sloped armour and LOS being equal doesn't translate to the afforded protection being equal.

 

Either case seems likely IMO, especially considering their track record of underestimating/misjudging Soviet ammunition.

 

 

Anyway, I think we need to stay critical even of their official documents as they seem to be wrong or inconsistent in quite a few cases.

 

3 minutes ago, TokyoMorose said:

TL;DR - The Brits judged purely by amount of frontal area ammo is stowed in, irrespective of how armored or safe that area is. By that logic, T-72s have the safest ammo stowage of any modern tank...

Yup, just like their preferance for not having a unitary sight, they seem to often come to the wrong practical conclusions.

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9 hours ago, Liberator said:

480 mm is if I correctly understood the speech about protection for special armor, which experienced for Challenger 1. But about the glacis a lot of questions. 275 mm probably without special armor.

 

The way the sentence mentioing this is phrased, the 480/340 mm are the actual protection achieved by the Challenger 1 tank with Chobham special armor. The 500/275 mm are the design goal from a time, when the Challenger 1 was still in development.

 

2 hours ago, Clan_Ghost_Bear said:

What was the British rationale for not liking the ammo storage in the turret?

 

If you read through this topic, there is a snipplet from a British report on the M1 Abrams (the M1 Abrams was considered as an alternative to the Challenger 1), which mentions that most of the initial tests with the "safe" ammo separation actually failed, apparently because the bulkhead was not strong enough to deal with the pressure in the split seconds before it was successfully lowered via the blow-off panels.

 

Other than that, the Abrams' turret ammo storage increases the frontal profile while at the same time requiring additional armor at the turret sides (due to the fact that such a large quantity of the total ammo load is located within a single place; one does not want a single RPG to take away essentially the complete ammo loadout of a MBT). The British - and the Germans - believed that putting more ammo in the well-protected frontal section of the hull was desirable.

 

1 hour ago, Scav said:

I do have to point out how this table seems quite inaccurate or atleast inconsistent, even if it just refers to the hull armour, both the T-64 and T-72 reach higher than 270-290mm. 

 

This is from the late 1970s, there was still quite a lot of development going on before the Shir 2 tank became the Challenger 1 (one difference being the improved turret armor of the latter), while NATO didn't know much about the Soviet tanks.

 

The hull of T-64 and T-72 were believed by the British to feature only 100 mm steel sloped at 68.5° as frontal armor (which is 272 mm steel along the line-of-sight), a major underestimation.

 

1 hour ago, Scav said:

I've noticed that as well, they for some reason think the 2A4 was poorer armoured than the stillbrew chieftain, something I find quite funny.

 

The statement about the Leopard 2's turret armor being worse than the Chieftain with Stillbrew is directly focused on frontal protection (i.e. when being hit straight on) against kinetic energy penetrators of the turret front. The Leopard 2 apparently has 400-450 mm (depending on location), with the gun mantlet potentially being worse armored (~350 mm; at least that seems to be the conlcusion of the analysis done by @Laviduce) - so the Chieftain with Stillbrew seems to be quite a bit better armored.

 

1 hour ago, Scav said:

So, ~450mm of KE protection at the tested spots isn't far off let alone superior to the 2A4's ~430mm which was achieved by firing what looks to be DM53 at it. 

  Reveal hidden contents

xNAFPmz.jpg

Right hand one was used for turret testing according to that slide and it looks an awful lot like DM53, the left one looks like DM33.

 

So, considering L23A1 is notably worse than DM53, I think it's safe to say it would  do worse against a 2A4 turret than DM53 and the protection given by the armour would "increase" as a result.
 

All of that is from a stricly frontal attack, the sides of a 2A4 are also fitted with spaced armour and the LOS of it would reach around 620-640mm if hit at a 30° angle.

 

The 120 mm DM53 APFSDS round did not exist at the time of the Swedish tests and certainly wasn't delivered to Sweden. The photograph most likely shows a test projectile made only for the evaluation.

 

The data for the Leopard 2 tanks apparently comes from Krauss-Maffei and likely does not reflect what Sweden was able to test (it would be very odd to let Sweden fire its APFSDS rounds and shaped charges at every possible armor package ever made for the Leopard 2, if they are only interested in the latest one(s)).

 

1 hour ago, Scav said:

So either they didn't think the Soviets couldn't make better ammo than they did, or they didn't understand that long rods perform better against sloped armour and LOS being equal doesn't translate to the afforded protection being equal.

 

The extract from the book regarding Chieftain''s armor already shows that the British underestimated the performance of Soviet rounds, it says that (in 1981) the penetration of the T-72's 125 mm gun was estimated to be 420 mm for steel penetrators and 475 mm for tungsten penetrators point-blank at normal (aka 0 meters, 90° impact angle). The United States also underestimated the performance of the Soviet 125 mm gun and ammunition, one could say they did that to an even greater extent.

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12 minutes ago, SH_MM said:

The 120 mm DM53 APFSDS round did not exist at the time of the Swedish tests and certainly wasn't delivered to Sweden. The photograph most likely shows a test projectile made only for the evaluation.

Well, it would've been a prototype if anything, but the similarity is too striking for it to be a coincidence, perhaps it was just a round with the same function and rough dimensions.
 

13 minutes ago, SH_MM said:

The data for the Leopard 2 tanks apparently comes from Krauss-Maffei and likely does not reflect what Sweden was able to test (it would be very odd to let Sweden fire its APFSDS rounds and shaped charges at every possible armor package ever made for the Leopard 2, if they are only interested in the latest one(s)).

If this is true, then I agree, but I don't know for sure.

 

14 minutes ago, SH_MM said:

The extract from the book regarding Chieftain''s armor already shows that the British underestimated the performance of Soviet rounds, it says that (in 1981) the penetration of the T-72's 125 mm gun was estimated to be 420 mm for steel penetrators and 475 mm for tungsten penetrators point-blank at normal (aka 0 meters, 90° impact angle). The United States also underestimated the performance of the Soviet 125 mm gun and ammunition, one could say they did that to an even greater extent.

Yep, it seems only Germany fully realised the 125mm potential (atleast looking at the Krapke threat diagram) although the leo 1 part probably isn't correct.

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10 minutes ago, Molota_477 said:

What page is the data of 480/340 on? 

 

I don't know, this is what I have read in another discussion on another website. As I said I don't own the book yet. I might have mistaken the values from a random discussion with a footnote from the book, which says that the Challenger 1 mounted armor providing "equivalent amounts" to 430 mm for the turret and 315 mm for the hull.

1187995418_Page1.thumb.jpg.8a19c7d83cb87

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3 minutes ago, SH_MM said:

 

I don't know, this is what I have read in another discussion on another website. As I said I don't own the book yet. I might have mistaken the values from a random discussion with a footnote from the book, which says that the Challenger 1 mounted armor providing "equivalent amounts" to 430 mm for the turret and 315 mm for the hull.

1187995418_Page1.thumb.jpg.8a19c7d83cb87

"Equivalent amount" might refer to the mass of special armor which mounted on MBT-80 and provide 480mm protection for turret and 430mm for front hull:

14662_2000.jpg

Note the endnote"6"

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24 minutes ago, Molota_477 said:

"Equivalent amount" might refer to the mass of special armor which mounted on MBT-80 and provide 480mm protection for turret and 430mm for front hull:

 

I don't think that it refers to mass of the special armor. Note that the following document seems to list the MBT-80 with "430 mm+" protection, while also listing the effective hull armor thickness of Centurion and Leopard 1 (implying that the figures for the other tanks might also be hull armor).

 

pasted%20image%200%20(4)_a0ca159c91df075

 

In documents from 1969 and 1970, it is already mentioned that Chobham armor has a mass efficiency of above 1.0, so 430 mm steel-equivalent mass should provide a noteworthy larger amount of armor protection. It also would be odd to mix figures in milimeters with tons (for the applique armor) without even specifying that the milimeters is meant to be steel-equivalent mass.

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14 minutes ago, SH_MM said:

steel-equivalent mass

Yes, I misread it before, so it makes sense that the ''up armour'' Challenger 1's turret can obtain up to 500mm protection against some specific KE rounds while the thickness of steel-equivalent mass only 430mm.I think the same theory also is appropriate for the glacis.

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6 hours ago, Molota_477 said:

14433_2000.jpg

 

It seems that the British documents use values for protection along the full 60° frontal arc.

 

The minimum thickness of the Leopard 2 turret cheek armor along the frontal arc is roughly 660 mm.

860/660*350 = 456 mm

860/660*420 = 547 mm

 

That matches the current interpretation of this graph from the Swedish documents:

kDGjKnO.png

 

Furthmore there is the statement about the M1A1 HA's DU armor providing 15° more protection than the Dorchester armor of the Challenger 2. Given that the former is believed to provide 600 mm protection vs KE along the frontal arc based on the Swedish documents (or about 660 mm from straight on assuming that the armor efficiency stays the same regardless of horizontal slope), this would put the Challenger 2 at 510 mm (560 mm head-on) vs KE. The protection requirement for the turret was armor equivalent to 500 mm steel vs KEPs (along the frontal arc?).

 

Even more so, the Brits believed the M1 Abrams to feature turret armor providing 340 mm equivalent protection vs KE along the frontal arc. That would be equivalent to 392 mm vs KE from head-on. A CIA document puts the M1 Abrams' turret at 400 mm vs KE.

 

 

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2 hours ago, SH_MM said:

 

It seems that the British documents use values for protection along the full 60° frontal arc.

 

The minimum thickness of the Leopard 2 turret cheek armor along the frontal arc is roughly 660 mm.

860/660*350 = 456 mm

860/660*420 = 547 mm

 

That matches the current interpretation of this graph from the Swedish documents:

 

 

Furthmore there is the statement about the M1A1 HA's DU armor providing 15° more protection than the Dorchester armor of the Challenger 2. Given that the former is believed to provide 600 mm protection vs KE along the frontal arc based on the Swedish documents (or about 660 mm from straight on assuming that the armor efficiency stays the same regardless of horizontal slope), this would put the Challenger 2 at 510 mm (560 mm head-on) vs KE. The protection requirement for the turret was armor equivalent to 500 mm steel vs KEPs (along the frontal arc?).

 

Even more so, the Brits believed the M1 Abrams to feature turret armor providing 340 mm equivalent protection vs KE along the frontal arc. That would be equivalent to 392 mm vs KE from head-on. A CIA document puts the M1 Abrams' turret at 400 mm vs KE.

 

 

Interesting, I think in the case of the Challenger it doesn't refer to added protection equivalent but actual LOS thickness of the entire package.

As for the number of the leopard 2, B seems more or less correct, not sure about C though, it's definitely interesting that it keeps coming back that C tech had this much added over the first variants, the weight increase doesn't seem like it would be enough, perhaps they managed this by using very "light" materials such as ceramics and replacing some steel with lighter alternatives?

Maybe they replaced the entire array and made it more efficient with higher hardness or something?

 

As for Challenger 2, it seems that in the Hellenic tank trials the tank was critisised for it's poor hull protection and lack of roof protection, similar to the Leclerc in terms of protection, so ~550 wouldn't seem too far off, it's definitely worse than the M1A2 and leopard 2A5 as suggested.

 

I still need to find the original magazine where they talk about the trials though.

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The Greek article on the trials is just two pages long and doesn't go into detail about armor protection other than saying that the Leopard 2A5 had the best, followed by the M1A2 Abrams and that the Challenger 2's armor was disappointing, being merely better than the Leclerc. The CR2 features improved roof armor over the Challenger 1, it should be better than the Leclerc and Abrams in this regard.

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On 11/29/2018 at 12:59 AM, SH_MM said:

 

I don't think that it refers to mass of the special armor. Note that the following document seems to list the MBT-80 with "430 mm+" protection, while also listing the effective hull armor thickness of Centurion and Leopard 1 (implying that the figures for the other tanks might also be hull armor).

 

pasted%20image%200%20(4)_a0ca159c91df075

 

In documents from 1969 and 1970, it is already mentioned that Chobham armor has a mass efficiency of above 1.0, so 430 mm steel-equivalent mass should provide a noteworthy larger amount of armor protection. It also would be odd to mix figures in milimeters with tons (for the applique armor) without even specifying that the milimeters is meant to be steel-equivalent mass.

Finally I found the document of GSR3572, the data of 480 and 430 only refer to the KE protection, but not the mass equivalent thickness, and there is a heaviest protection level up to 540mm.(But it is so heavy and very hard to offer full protection on hull under MLC70, while MLC60 or 55 tonnes only is a basic model without full protection on hull, note "full protection" means including side protecion within a limited angle. 

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12 hours ago, Molota_477 said:

Finally I found the document of GSR3572, the data of 480 and 430 only refer to the KE protection, but not the mass equivalent thickness, and there is a heaviest protection level up to 540mm.(But it is so heavy and very hard to offer full protection on hull under MLC70, while MLC60 or 55 tonnes only is a basic model without full protection on hull, note "full protection" means including side protecion within a limited angle. 

However, apparently this has little to do with Challenger 1. 

MBT-80 looks very promising, sad that the British could not start it in production.

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2 hours ago, Liberator said:

However, apparently this has little to do with Challenger 1. 

MBT-80 looks very promising, sad that the British could not start it in production.

Yes , the GSR 3572 only for MBT-80, so that's all I mean.

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59 minutes ago, Liberator said:

540 mm Hull and turret or only turret? And what CE protection MBT-80?

 

Both hull(full protection, including front arc of 50°) and turret at 69 metric tonnes.

While combat weight at 64 tonnes——fully protected turret + hull protection without enough side armor(only front glacis).

 

The number of 540mm actually meams a specific KE threat which could penetrate up to 540mm RHA at 1km range(It was assumed as Soviet DU APFSDS M1980). MBT-80's Chobham armour was desired to defeat such threat after some meetings in 1978.

 

Besides these two heaviest schemes, there are also 2 correspondly intermedial schemes have 480mm protection level, but still too heavy, the full protection scheme weight 65 t, and the "only front protection on hull" version weight 62 t.

 

Note that all of these schemes are only on paper discussion.

 

And the level of 430mm RHA actually is the original requirement for MBT-80 before 1978. They thought it can be achieved within MLC60 which the turret is fully protected while the hull only has upper glacis.

 

As for CE threat, they specified the need of againsting 130mm caliber shape charge(also is front ±25° in azimuth).

 

That's all I have seen.

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1 hour ago, Molota_477 said:

 

Both hull(full protection, including front arc of 50°) and turret at 69 metric tonnes.

While combat weight at 64 tonnes——fully protected turret + hull protection without enough side armor(only front glacis).

 

The number of 540mm actually meams a specific KE threat which could penetrate up to 540mm RHA at 1km range(It was assumed as Soviet DU APFSDS M1980). MBT-80's Chobham armour was desired to defeat such threat after some meetings in 1978.

 

Besides these two heaviest schemes, there are also 2 correspondly intermedial schemes have 480mm protection level, but still too heavy, the full protection scheme weight 65 t, and the "only front protection on hull" version weight 62 t.

 

Note that all of these schemes are only on paper discussion.

 

And the level of 430mm RHA actually is the original requirement for MBT-80 before 1978. They thought it can be achieved within MLC60 which the turret is fully protected while the hull only has upper glacis.

 

As for CE threat, they specified the need of againsting 130mm caliber shape charge(also is front ±25° in azimuth).

 

That's all I have seen.

Yes, I read about this before.
It is interesting that for 130 mm CE. I know the parameters of 5 and 6 inch CE for testing, but for the first time I hear about 130 mm.

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  • Similar Content

    • By Akula_941
      Anti-air bobcat design to take away driver's hearing in maximum efficiency

      SH11  155mm SPG


    • By Serge
      A nice picture to start :

      ZAHA
    • By Sturgeon
      Let's say you're developing a tank with a unique (AKA non-historical) gun for one of our competitions here on SH. It would be nice to have an idea of the size of the gun, its shells, and what their performance both in terms of shell weight and velocity but also penetration, wouldn't it? Well, fortunately there is a way to do this with reasonably accurate results using your solid modeling software and some free to use browser tools.

      First, you want to have a general idea of the size and performance of your gun. For this example, I decided I wanted an optimized, high velocity 85mm caliber gun with a case about as big as the 7.5cm KwK 42 (as it happened, I ended up with a case that had significantly greater volume, but that fact is unimportant for this example). The cartridge I decided on has a 130mm wide rim and a 640mm long case, of course in 85mm caliber. My first step was to model this case in SolidWorks:


       
      You will also need to model your projectile, in this case a tungsten-carbide cored APCR round:


       
      Next, we need a bit of freeware: A Powley computer. Originally developed by DuPont engineers for small arms ammunition, the Powley computer is an accurate enough tool to use for much larger tank rounds as well! When you click the link, you'll be greeted with this screen:
       

       
      You'll note the dimensions are in inches and this thing called "grains" (abbreviated "gn"). The grain is an archaic Imperial mass unit equal to 1/7000th of a pound which is still used in the small arms field, today. Another quirk of small arms has the case capacity - a volume measurement - listed in grains as well. This is in fact grains of water (gn H2O), or the weight of water that will fill the case to the top. To find this, simply multiply the volume in cubic centimeters by 15.43 - which is also the exchange rate between the metric gram and grains mass.
       
      Finding the volume of the case is easy with a solid modeling program; simply model the interior as a solid and find the volume of that solid:


       
      Filling in my Powley inputs gives me this:
       

       
      Note that I typically use the diameter of the projectile across the driving bands for "Bullet Diameter", but it really makes very little difference.
       
      So far, though, we haven't actually produced any results. That's because our gun is well outside the bounds of DuPont production IMR powders, hence the output "Much slower than (IMR) 4831" in the lower left. So, we need to override the computer by checking the box next to the blue "Pressure" function, and typing in a pressure value in CUP that is reflective of tank guns of whatever era we are trying to represent. My tank gun is trying to represent something from about the late 1940s/early 1950s, so I'm going to use 45500 CUP EDIT: USE 41000 CUP for APCBC and 42800 CUP FOR APCR (or better yet, do your own calibration!):
       

       
      This gives me an estimated muzzle velocity of 3,964 ft/s for my L/50 barrel. Not bad! Note the outputs on the left, which tell you a bunch of fun facts about your round but aren't terribly relevant to what we're doing here today. Next, we need to put this gun's performance in terms of penetration. The way I like to do this is through comparative analysis.
       
      The first thing we need is to know to find penetration the ballistic performance of our round. We can estimate this using JBM's ballistic calculator and a few rules of thumb. When opening the calculator, the first thing you'll see is this:
       

       
      We care about basically none of these settings except BC, velocity, and maximum range. Caliber, projectile weight, chronograph distance, etc are all pretty irrelevant to us. Keep the environmental settings (temperature, pressure, etc.) set to their defaults. First, change the ballistic coefficient type from G1 to G7 using the dropdown menu. Then, change the muzzle velocity from 3000 to whatever the muzzle velocity was that was calculated by the Powley computer. Finally, set the maximum range to your desired distance - in my case 2,000 yards.

      For my round, I now have inputs that look like this:
       


      We also need to get some idea of how fast our projectile loses velocity, something we can't know for certain without actually building a real gun and test firing it - or at least without some really sophisticated simulations. However, projectiles with the same shape tend to fly the same way, and that's something we can exploit here. To figure this out, we need a graph showing us the performance of a real-life gun. Fortunately, there is a handy one for an IRL gun similar to what I'm designing, the 90mm M3 from World War II, and its M304 HVAP-T, which is broadly similar in construction and shape to my 85mm APCR projectile:
       

       
      Based on this chart, we see that the M304 should drop from its 3,350 ft/s muzzle velocity to about 2,500 ft/s at 2,000 yards. Doing a little trial and error with JBM tells me that this means the M304 has a G7 ballistic coefficient of about 1.13.
       
      Now, our projectile will not have the same ballistic coefficient, due to it being a different size and mass. But, we can figure out what its ballistic coefficient would be by finding its sectional density and comparing that to the sectional density of M304. To find sectional density, take the projectile's weight in grains and divide it by the square of the projectile's diameter in inches, times 7000. So for M304, we get:
       

       


      And for my 85mm, we get:


       

       
      This means that the ballistic coefficient for an identical-shape projectile with our size and weight will be about 1.019/1.330 - or 76.6% as much - as that of the 90mm M304. That means a BC of 0.866 G7 should be approximately correct for my 85mm APCR round. Let's plug that in:


       
      And then scroll down to the bottom to click "calculate", which gives us a big ol' chart that goes out to 2,000 yards:
       

       
      O-Kay! Now we have some data. It looks like at 2,000 yards, my projectile holds about 2,800 ft/s striking velocity. It's important to note here that what we really care about isn't the striking velocity of the projectile per se, but the velocity and energy of the projectile's core. The core is what's actually doing a lot of work to the armor, so for now let's stop thinking in terms of the whole projectile, and take a look at these two cores, that of the M304 90mm HVAP, and that of my 85mm APCR round. The core of the 90mm M304 is an approximately 8 pound lump of tungsten-carbide that is about 45mm in width. My penetrator is also 8 pounds, but it's longer and thinner in proportion - just 40mm wide, rather than 45mm. This means my penetrator will penetrate more armor at a given striking velocity, and we can estimate how much more by taking the specific energy of the rounds and comparing them. That is, the energy in Joules of the penetrator alone, divided by the penetrator's diameter squared:
       

       


      So the specific energy at 2,000 yards is about 826J/mm^2. Now, we need to find out at what impact velocity the M304 penetrator produces this same specific energy. Do do that, we go backwards, using the figures for M304:
       

       

       
      Therefore, the equivalent impact velocity for my 85mm APCR round at 2,000 yards is 3,150 ft/s for the M304. That means, in theory, that the M304 would have to impact a target at 3,150 ft/s to produce equivalent penetration of RHA to my 85mm APCR striking at just 2,800 ft/s.

      Now, we head back to that chart:


       
      On the left side of the graph, we put our cursor on the line that corresponds to approximately 3,150 ft/s velocity, and follow it over until it hits the curved line that corresponds with the angle of plate we care about - arbitrarily, let's pick 20 degrees. Then, we follow that point straight down until it hits the x-axis:


       
      Therefore, we estimate that at 2,000 yards, my 85mm has just over 10 inches of RHA penetration - not bad at all for a lowly APCR round!
    • By Walter_Sobchak
      Since we don't have a thread for British and Commonwealth tanks of WWII, I thought I would start one.  
       
      Check out this manufacturers instructional video on the Crusader.
       
       
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