Contemporary Western Tank Rumble!

[Mighty_Zuk]

21 minutes ago, LoooSeR said:

 

 

   Better word will be "a chance to neutralizes the projectile's warhead without initiating it." 

3/4 of warheads were neutralized. Rafael claims 50% rate IIRC, while IMI's fragment-free grenade offers 90% rate. 

[N-L-M]

10 hours ago, Karamazov said:

I give it as an example because it can be launched from a gun. They can shoot a leopard 2. 

Spike can't do it yet. Anyway - its caliber is not important. Because he hits the target from above

The caliber absolutely is important, Especially on a laser spot homer. Laser homers home in on the center of the laser illuminator spot which as you can probably guess within 2 seconds of thinking about the problem is splashed all over the side of the target, not the roof. Hitting things like a T-72 glacis or NATO box tank NERA arrays from a steep dive does help you get through it, the size of the warhead is still important cause you're still going through a lot of armor. On IIR missiles which do actually choose their point of impact on the roof, warhead size would seem less important, and yet every single one in production has a tandem warhead arrangement of non-negligible dimensions, so the simple dismissal of caliber as irrelevant doesn't pass the smell test.

10 hours ago, Ronny said:

But i have never seen report of laser designation difficulty for early version of Hellfire though.

I mean, if targeting pod on fighter can designate target from 72 km away  i would expect helicopter laser designator at least 1/8 as good as that.

Fixed wing aircraft designators are different from heli ones as they're operating from up high, and not down low where all the interference and dust is; they therefore have an easier time of things. And even then, the 40 NM range for ATFLIR is for a very new system in ideal conditions, and given with no reference target size. Spot size grows with distance, and while 50m accuracy may be enough to hit an industrial building, for example, it sure ain't good enough for a tank.

Also the fact that you're ignorant of real world issues and haven't bothered to use google before coming here is a point against you, not in your favor. But seeing as you seem to need a good hard whacking with some primary sources, git rekt:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a251803.pdf

The Hellfire had an average accuracy of 76% during ODS. And that was against a cooperative enemy!

10 hours ago, Ronny said:

so I really skeptical that laser designation is problematic at merely 8 km

Laser guidance won't work through cloud cover.
Here's another freebie:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a434233.pdf

skip ahead to chapter 2 part 2 and git larned. I'm going to stop spoonfeeding you at some point, so enjoy it while it lasts.

10 hours ago, Ronny said:

There are others threat to helicopter which are far far more dangerous to helicopter than tanks, for example: SHORAD such as Tor-m1 or Pantsir-S1. Compare to their missiles, the capability of MBT's MPHE is rather pathetic. 

There are indeed other threats to helis, but effective gun counterfire from literally any target is not doing the helis any favors, and time fuzed HE which reaches helis behind terrain masking is a big threat compared to LOS-limited command-guided missiles such as those AA systems fling.

10 hours ago, Ronny said:

Also what if we use something like this:

Ukrainian knockoff beam riders are even lower energy and sadder. Not a good idea.

Also, laser illumination is like most EM "beams" not a binary "is/isn't illuminated" business, you have a lobe, and the sides of it are still enough to set off any LWR which isn't ancient.

Also 0.3 sec to correct an offset of 3-5m (which is the min offset you'd need to get the target mostly out of the main lobe) is very optimistic for any ATGM.

And to top it all off, that ATGM is extremely low energy and sad, being a 125mm beam rider.

Get with the times, this isn't the 1960s, GLATGMs are not a good idea.

5 hours ago, Mighty_Zuk said:

LAHAT is only a shitshow if you insist on analyzing its capabilities OUTSIDE of its historical background.

It was devised for the Merkava 2 tank, long before the Spike even had half the capabilities it has today.

No, even within that context it's still low energy and sad.

And at the time it was in development the Tamuz 1 was already fielded in significant numbers, and had the RF link allowing the operator to select the target for contrast lock after launch, so no. LAHAT is sad and Tamuz is a good boy.

5 hours ago, Mighty_Zuk said:

Another point you've forgotten is that a helicopter is not required for remote designation. It can be done via infantry.

Nice assumption there, but I haven't forgotten. Problem with infantry is that they're the squishiest thing on the battlefield, and lasing a tank while someone else far away fires a slow missile at it is a very good way to get plastered by HE from an angry tank. Squishies gonna squish, even if they have laser designators.

5 hours ago, Mighty_Zuk said:

And they themselves would have a low combat signature.

Laser illuminators are not in any way low sig. At all.

5 hours ago, Mighty_Zuk said:

Caliber is of course a non-factor because of top attack

Not the kind of dive LAHAT (and indeed Laser Hellfire) perform, as they're homing in on the spot painted on the front or side of the vehicle from a ground based designator. Hell you can even see this in the LAHAT promotional material if you actually bother to look.

Also, if it's that irrelevant, why do they bother with full size warheads and a precursor?
Obvious answer time: because it's damned far from irrelevant.

5 hours ago, Mighty_Zuk said:

even other similar sized missiles developed by the same company.

What non-Spike ATGM-sized missiles has Rafael developed recently?

And how much larger, proportionally, are their warheads compared to those of the Spike family?

6 hours ago, Mighty_Zuk said:

Only today are LAHAT missiles irrelevant, hence their withdrawal from service a long time ago

I'd like to see a single source confirming that it ever entered service. Cause all I see is the bunchpics from when they were testing it, and it seems to never have entered service anywhere. Got any source to change my mind on this topic? Considering how the Tamuz was in service long before LAHAT was properly developed, and was a MUCH more effective missile, LAHAT would appear to be completely useless, particularly for a cost-effectiveness conscious military.

 

You know, there's a reason LAHAT seems to have died a quiet death with nobody appearing to have actually adopted it into service.

[Ronny]

 

 

 

 

 

 

 

6

5 hours ago, N-L-M said:

 

Fixed wing aircraft designators are different from heli ones as they're operating from up high, and not down low where all the interference and dust is; they therefore have an easier time of things. And even then, the 40 NM range for ATFLIR is for a very new system in ideal conditions, and given with no reference target size. Spot size grows with distance, and while 50m accuracy may be enough to hit an industrial building, for example, it sure ain't good enough for a tank.

Also the fact that you're ignorant of real world issues and haven't bothered to use google before coming here is a point against you, not in your favor. But seeing as you seem to need a good hard whacking with some primary sources, git rekt:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a251803.pdf

The Hellfire had an average accuracy of 76% during ODS. And that was against a cooperative enemy!

Laser guidance won't work through cloud cover.
Here's another freebie:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a434233.pdf

skip ahead to chapter 2 part 2 and git larned. I'm going to stop spoonfeeding you at some point, so enjoy it while it lasts.

I checked your source, but it seem that particular occasion was due to insect sticking to the seeker head more than anything else. Furthermore, it is impossible to compare when we only have Hellfire accuracy and nothing else, for example the accuracy of Sabot, Heat and MPHE round. For comparison, the PK of air to air BVR missiles  is 55 %, the PK of anti aircraft cannon in Viet Nam war was 3-5%. Yet no one can doubt their danger. So I still think PK of 0.76 is pretty decent 

 

ATFLIR IOC in 2002 about 17 years ago, there are many newer system now such as ATP-SE.

About spot size, this is what i can find:

 

With beam width of 0.25 mrad or 0.01432394 degree, spot size at 74 km is 18 meters and spot size at 8 km is 2 meters 

 

 

 

Quote

There are indeed other threats to helis, but effective gun counterfire from literally any target is not doing the helis any favors, and time fuzed HE which reaches helis behind terrain masking is a big threat compared to LOS-limited command-guided missiles such as those AA systems fling.

57E6 and 9M330 both have proximity fuse so they can also  attack heli behind terrain masking

AIM-9X has both terminal seeker and proximity fuse

Never mind the fact that unlike MPHE tank round, these SHORAD all out range AGM-114 significantly and can be guided toward targets. Whereas for MPHE tank round, the helicopter can either stay further than 5 km or higher altitude and they would be effectively outside the engagement envelope . MPHE round are not guided either so i highly doubt that it can engage fast moving helicopter, can tank FCS even lead a helicopter moving at 200 km/h or faster? Non APFSDS round seem to have very significant gravity drop at distance:

 

 

 

M820 round need about 4.2 seconds to fly out to 3 km, in that time a helicopter with speed of 200 km/h could have move 222 meters. At 5-8 km, the situation will be even worse for an unguided round. Overall, MPHE tank round seem like pretty pathetic threat to helicopter when comparing to dedicated SHORAD and MANPADs, i do not think MPHE tank round is the reason for NLOS missiles.

 

 

 

 

 

 

 

 

2

Quote

Ukrainian knockoff beam riders are even lower energy and sadder. Not a good idea.

Also, laser illumination is like most EM "beams" not a binary "is/isn't illuminated" business, you have a lobe, and the sides of it are still enough to set off any LWR which isn't ancient.

Also 0.3 sec to correct an offset of 3-5m (which is the min offset you'd need to get the target mostly out of the main lobe) is very optimistic for any ATGM.

And to top it all off, that ATGM is extremely low energy and sad, being a 125mm beam rider.

Get with the times, this isn't the 1960s, GLATGMs are not a good idea.

No, even within that context it's still low energy and sad.

 

[Ronny]

6 hours ago, N-L-M said:

Laser guidance won't work through cloud cover.
Here's another freebie:
https://apps.dtic.mil/dtic/tr/fulltext/u2/a434233.pdf

skip ahead to chapter 2 part 2 and git larned. I'm going to stop spoonfeeding you at some point, so enjoy it while it lasts.

Yes, but neither does infrared, furthermore, i don't think this is spoon feeding, provide source to what one claim is pretty common accepted rules for proper discussion. Burden of proof lies upon a person making claims

 

 

Quote

Also, laser illumination is like most EM "beams" not a binary "is/isn't illuminated" business, you have a lobe, and the sides of it are still enough to set off any LWR which isn't ancient.

Also 0.3 sec to correct an offset of 3-5m (which is the min offset you'd need to get the target mostly out of the main lobe) is very optimistic for any ATGM.

And to top it all off, that ATGM is extremely low energy and sad, being a 125mm beam rider.

Get with the times, this isn't the 1960s, GLATGMs are not a good idea.

I tried to look up laser side lobe but really i can't find anything, unlike radio frequency beam:
Laser beam pattern:
 

 

 

Radar beam pattern:

 

I am not sure if that because laser beam has no side lobe or it is extremely in significant that it is not mentioned 

 

Quote

 Spot size grows with distance, and while 50m accuracy may be enough to hit an industrial building, for example, it sure ain't good enough for a tank.

I have a look at several laser designators:
Can be carried by infantry, max range 20 km => basically, you can illuminate enemy tank and they can't do anything
Beam divergent: 130 micro radiance = 0.007448 degrees.

At 20 km the beam spot is 2 meters in diameter, at 8 km the beam spot is only 1 meter in diameter 

 

[Ronny]

12 hours ago, Mighty_Zuk said:

The range of HE is lower than that of APFSDS, in a consideration of only the flight characteristics of the projectile.

However, what limits APFSDS range is not really how long it can fly. It can go for tens of kilometers with ease. It just won't retain the necessary velocity to penetrate a target. 

A specific APFSDS could be effective to 3km for one target, 1.5km for another more armored target, and completely ineffective to another even more armored target.

HE is not range-limited, and with fin stabilizers could fly out to a pretty good range. Russia (UVZ) claims the T-90 can fire its HE shell out to 12km.

 

It's physically possible, but the bottleneck would be the sights that probably won't even recognize the pixel they're looking at, at that range.

 

So if you can see a target 6km away, you can be sure lobbing HE shells is possible. In the IDF it's fairly routine to practice firing them out to 5km, and that's not really an exceptional feat in the west or anywhere.

 

 

But it won't hit moving target at that range right?

[Wiedzmin]

@Molota_477

what is the poin to make fake/collages from real report which doens't contain such schemes ? real report contain only turret scheme and text description for CR1 turret, armour scheme was excluded from this report, only text and scheme of whole turret without protection levels, and report doesn't contain anything about "200mm at normal" and "480mm" IIRC

 

 

report also doens't give numbers for CR2 turret, only for CR1 MLI(yes it says that turret level more or less similar) but not for Cr2

 

 

[Molota_477]

I have said that was estimated

[Molota_477]

BTW, 480/750 was based on anther RARDE Report about ENT, and the report with options comparison did wrote some data of protection level of CR1 if you have the report you can find it in annex of Leo 2.

[Wiedzmin]

5 minutes ago, Molota_477 said:

BTW, 480/750 was based on anther RARDE Report about ENT

yes there is several values, but it is better to give the real quotes and sources references , and not to draw it yourself so that it wouldn't raise questions and suspicions

 

and IIRC there no reports with 200mm for turret side from CE

 

8 minutes ago, Molota_477 said:

I have said that was estimated

i only seen this images on otvaga

[Molota_477]

1 hour ago, Wiedzmin said:

yes there is several values, but it is better to give the real quotes and sources references , and not to draw it yourself so that it wouldn't raise questions and suspicions

 

and IIRC there no reports with 200mm for turret side from CE

hmm, I see,

I will take care on such thing later.

200mm is based on the table of Chieftain Burlington report, but not accurate value so I just estimated it.

1 hour ago, Wiedzmin said:

i only seen this images on otvaga

For now I only post them on Chinese speaking platform, and have noted about it.

[FORMATOSE]

So, it looks like an old British declassified DEFE document ...but it is not.

[SH_MM]

Is this snipplet taken from the real document or only made to look as if it was?

 

 

[Militarysta]

@UP

The second option.

 

More or less values confirmed in sevral documents give us sucht picture:

 

NATO:

Leopard 2A0-2A4:

350mm vs APFSDS i 700mm vs HEAT (hull and turret)

Challenger 1:

435mm vs APFSDS i 700mm vs HEAT (turret)

300mm vs APFDS i 500mm vs HEAT (hull)

M1:

400mm vs APFSDS  i 750mm vs HEAT (turret)

350mm vs APFSDS i 750mm vs HEAT (hull from FMV files - to validation)

Leopard 2A4 late  + all older 2A0-A4 after factory F6 

420mm vs APFSDS and 800mm vs HEAT (hull and turret )

 

And Soviet muniotion it those days:

APFSDS-T (all for 2km)

3BM9 1969 240 mm RHA for 0 deg.

3BM15  1972 310 mm RHA for 0 deg.

3BM26 1985 410 mm RHA for 60 deg. 450 mm RHA for 0 deg.

3BM32  1987 (serial prod.) 500mm RHA for 60 deg.

3BM42  1988 (serial prod)  440mm stali for 60 deg. - but this round was developed to overpas NERA armour so RHA eqivalent give us nothing.

ATGM:

9M113  1974 ~600 mm RHA

9M114 1976 650 mm RHA

9M112  1977 600 mm RHA

9M111M  1980 600 mm RHA

 

And really funny is when we put in  compare T-64B, T-72A, T-80B and...T-80U and T-72B. More or less soviet tanks where mucht more better armoured vs KE but main armour where circa 30% less vs CE then in western tanks...up to T-80U and T-72B where CE protection was on par whit western ones.

[SH_MM]

The data for the M1 Abrams isn't directly comparable:

• the hull armor of the Abrams is stated as 320 mm in British documents, the 350 mm is valid for the M1A1 and M1A2 (the M1E1 prototype featured a weight simulator added to the hull, implying hull armor weight was (slightly) increased).
• the turret armor of the Abrams is listed as 340 mm at ±25° by the Brits, which would be equal to ~400 mm at 0°. The data for the Challenger 1 and Leopard 2 (against old steel APFSDS with WC core) are for  ±30°. Based on the Swedish leaks, the data for the Leopard 2A4 with C-technology armor is also for ±30°.
• the M1A1 is listed in a CIA document with 380 mm protection vs APFSDS (along an unknown arc, but I believe it is also ±25°) - potentially this armor is not only designed to defeat steel APFSDS with WC core.
• the hull of the Challenger 1 was listed as 275 mm protection in a 1980 document stating predicted protection and penetration levels.

[heretic88]

@Militarysta 

And the 3BM22? It should penetrate around 380mm @ 2km, but would it be enough against early M1 or Leo-2A0? While I doubt it would penetrate them at 2km, but what about shorter ranges, like 1km?

Also the 115mm 3BM28 with DU core?

[Militarysta]

17 minutes ago, heretic88 said:

@Militarysta 

And the 3BM22? It should penetrate around 380mm @ 2km, but would it be enough against early M1 or Leo-2A0? While I doubt it would penetrate them at 2km, but what about shorter ranges, like 1km?

Also the 115mm 3BM28 with DU core?

 

BM15 and BM22 was tested in Germany and Poland and definetly no - this round fails completly against spaced and spaced + NERA targets. About this I have no single doubt. -NERA just cracked whole penetrator  and set tungsten subrod in non linear way - so it hit backplate mostly its no front but side way. But im not so sure about BM26 - this roudnd was developerd to overpas I gen western special armour and completly diffrent build (whit stungsten subrod (od slug) in tail not in nose like in Bm15/22 was made to burst all NERA layers and made situation "tungsten sub rod vs backplat only". God idea and IMHO against erly Leporad 2A4 ot CR1 hull - enought. 

From some polish doc I just now that Germans in 1988 just...forgot about NERA layers and start to use ceramic tiles in sevral layers and shapes to incarase protection against long rod monolitic WHA and DU rods  - it was thread more dengour then estern partial rods. From other side - BM42 and BM32 was very heavy enemy and IMHO since KWS Leopard 2 was not protected agianst them.

[heretic88]

@Militarysta

Interesting! Thanks!

Just one more question: What do you think about the metal-polymer blocks found on T-55M/AM and T-62M? I know they were designed to defeat APDS, and surely made the tank immune to them. But what about APFSDS? Im thinking about the earlier models, like M735 and M774. 

[Molota_477]

8 hours ago, SH_MM said:

Is this snipplet taken from the real document or only made to look as if it was?

 

 

Of course from real documents.

21 hours ago, Sovngard said:

So, it looks like an old British declassified DEFE document ...but it is not.

Not very old, there're some files varied from 1985 to 1990.

[VertigoEx]

2 hours ago, Militarysta said:

 

BM15 and BM22 was tested in Germany and Poland and definetly no - this round fails completly against spaced and spaced + NERA targets. About this I have no single doubt. -NERA just cracked whole penetrator  and set tungsten subrod in non linear way - so it hit backplate mostly its no front but side way. But im not so sure about BM26 - this roudnd was developerd to overpas I gen western special armour and completly diffrent build (whit stungsten subrod (od slug) in tail not in nose like in Bm15/22 was made to burst all NERA layers and made situation "tungsten sub rod vs backplat only". God idea and IMHO against erly Leporad 2A4 ot CR1 hull - enought. 

From some polish doc I just now that Germans in 1988 just...forgot about NERA layers and start to use ceramic tiles in sevral layers and shapes to incarase protection against long rod monolitic WHA and DU rods  - it was thread more dengour then estern partial rods. From other side - BM42 and BM32 was very heavy enemy and IMHO since KWS Leopard 2 was not protected agianst them.

 

 

The BM26 seemed to be the temporary solution until the more advanced rounds could be delivered. IIRC the Soviet view of Western Armor was not spaced composite arrays. Rather multi layer arrays of steel, early ceramics and aluminum. This was the nature of some the arrays that the Bm32/42 was tested against. The BM26 would perform better against such targets but worst against advanced Spaced NERA arrays. I still agree that it would probably be sufficient at close range against the hull arrays of the Leo-2 and C1. Against the M1 it might pen the area around the driver, to his left and right I don't see the eroded remnants of the slug doing much damage after impacting the fuel tanks.

 

As for the M1A1 and BRL-2, it looks like it incorporates some substantial weight with the weight simulators. I have never looked at the CIA document that states the protection as 380 across the frontal arc. I have heard values ranging from 400 to 450mm across the frontal arc.

 

Thinking out loud here. The M833 and BM42 have similar rod dimensions, with the M833 being a monoblock DU design vs BM42 segmented W.  While the Bm42 impacts at higher velocity, the design is less suited against composite arrays.  Any thoughts on which round would perform better against the spaced armor arrays at the time?

[SH_MM]

3 hours ago, Militarysta said:

From some polish doc I just now that Germans in 1988 just...forgot about NERA layers and start to use ceramic tiles in sevral layers and shapes to incarase protection against long rod monolitic WHA and DU rods  - it was thread more dengour then estern partial rods

 

Given that Frank Lobitz states that the Leopard 2A4 from 1988 (with C-technology armor) uses a modified form of Beulblechpanzerung, it seems likely that they didn't completely forget about NERA, but changed the amount/distribution, by adding thicker ceramic backplates/distrubers into the main array. Already in 1978 ideal armor was "NERA + multi-layered backplate containing ceramic tiles between steel layers".

 

26 minutes ago, VertigoEx said:

IIRC the Soviet view of Western Armor was not spaced composite arrays. Rather multi layer arrays of steel, early ceramics and aluminum. This was the nature of some the arrays that the Bm32/42 was tested against. The BM26 would perform better against such targets but worst against advanced Spaced NERA arrays.

 

Andrei_bt once posted a drawing showing how the Soviets believed the MBT 80's armor would look like during the 1970s. I.e. the frontal armor was believed to be a sandwich of steel, aluminium-oxide, normal aluminium and steel.

 

26 minutes ago, VertigoEx said:

I have never looked at the CIA document that states the protection as 380 across the frontal arc.

 

Well, to be fair it doesn't mention the frontal arc, but I believe that this seems to be self-evident based on the values. It is also noted that protection is dependending on the type of ammunition used, it could be the same situation as with the Leopard 2 (~450 mm protection against WC-cored steel APFSDS rounds, but only 350 mm against M111 Hetz and similar monobloc-designs).

 

Most estimates for the M1A1 are just random guesstimates from P. Lakowski and Zaloga ("M1A1 has 600 mm vs APFSDS").

[Militarysta]

3 hours ago, heretic88 said:

@Militarysta

Interesting! Thanks!

Just one more question: What do you think about the metal-polymer blocks found on T-55M/AM and T-62M? I know they were designed to defeat APDS, and surely made the tank immune to them. But what about APFSDS? Im thinking about the earlier models, like M735 and M774. 

 

In case DM33 (again - tested in Poland vs T-55AM Merida) - no doubt 2km penetration. The same Spike (700mm RHA warhed).

 

But in case older rods - interesting question! I will conisder German DM23 and DM13.

BDD Armour have layout:

60mm HHS and then 4 to 5 (dependet on angle) 5mm HHS palte spaced by 23mm melt in polymer. For most typical angle those plates wher sloped whit effective thickens (LOS) ca 10mm  so we had space layout 60+ 10 + 10 +10 + 10 + possible another 10 mm - more or less 100-110mm RHA maybe 120 on some anagle. BDD module is mounted 40mm from turret front. 

This You know:

 

So for T-62 we have at least 100-120mm RHA in spaced alyout + 40mm air gap  +  200 -157mm cast steel.

 

DM23 have

DM23 have circa 360mm long rod from tungsten alooys and DM13 had main part whit lenght only 230mm. How mucht RHA both can overpas? 

Finally I have hard data that at point blank whit V=1650m/s DM23 overpas 420mm RHA. [end hard data]

In 2km it was circa 380mm in 60 degree slopped plate(this is assumption)  

DM13? Still no hard data - we just can assume it should be circa 300-310mm in 60 degre plate but no evidence still. As I remember M774 should overpas ca 320-340mm in the same condition but it's estimatous not "hard data".

 

So DM23 should on typical Fulda Gap range 800m-1km overpas BDD armour on T-55AD/AM or T-62 whit BDD. But if DM13 was able to do this? Interesting question cose RHA penetration on 2km for this round should be equal to thicknes of BDD+Main armour on T-62. But spaced layout always will be mucht powerfull then RHA plates whit the same number of mm bot in one stack. On the other hand - on 800m Dm13 should overpass more then 320mm RHA... 

 

 

 

[Militarysta]

...

[FORMATOSE]

14 hours ago, Molota_477 said:

Of course from real documents.

Not very old, there're some files varied from 1985 to 1990.

 

I can't wait to read them.

[VertigoEx]

4 hours ago, SH_MM said:

Well, to be fair it doesn't mention the frontal arc, but I believe that this seems to be self-evident based on the values. It is also noted that protection is dependending on the type of ammunition used, it could be the same situation as with the Leopard 2 (~450 mm protection against WC-cored steel APFSDS rounds, but only 350 mm against M111 Hetz and similar monobloc-designs).

 

Most estimates for the M1A1 are just random guesstimates from P. Lakowski and Zaloga ("M1A1 has 600 mm vs APFSDS"). 

 

 

 

 

 

 

 

It is difficult to gauge how much armor is here. I measured the front plate thickness to ~40mm and side skirts and around ~50mm on a M1 on display.  It appears that the armor here is a 1.25' and 2.5' thick plate, slightly elevated by welds.

 

Looking at the pictures, it is safe to assume that some of the weight simulators are simulating the extra material required to extend the turret another ~200mm.  If the thicker plates are 2.5' alone represents the extra steel weight (or Titanium ? ) of the inserts then we are looking at ~65mm at angle. If the efficiency of the armor improves only slightly against monoblock KE APFSDS, then 450-480mm VS KE head on seems reasonable and 400-430mm across the frontal arc. 

 

Good enough against most ammo of the time, head on long range probably good enough against BM42/32 but I have doubts at close range.  Also important to consider that BRL-2 also was probably designed to deal with tandem shaped charges as well so not all the improvements would have gone into KE protection.  Even if the improvements are on the high end of 500-520mm of estimates I have seen. It certainly wasn't sufficient against ammunition that came online 5 years after it was deployed (BM46). 

 

 

The BM42 did perform worse against spaced armor arrays vs BM32 IIRC.

 

 

 

 

 

 

[SH_MM]

8 hours ago, VertigoEx said:

It is difficult to gauge how much armor is here. I measured the front plate thickness to ~40mm and side skirts and around ~50mm on a M1 on display. 

 

Side skirts are 65 mm.

 

8 hours ago, VertigoEx said:

If the thicker plates are 2.5' alone represents the extra steel weight (or Titanium ? ) of the inserts then we are looking at ~65mm at angle.

 

That depends on a lot of factors. The steel simulators are smaller than the actual turret frontal surface and there is also the option that some of the extra weight was used to improve the side armor of the turret, in order to keep a homogenous protection level at the frontal arc.

 

There are also the curious case of (some of?) the other M1E1 pilot(s) having much thinner weight simulators:

8 hours ago, VertigoEx said:

Also important to consider that BRL-2 also was probably designed to deal with tandem shaped charges as well so not all the improvements would have gone into KE protection. 

 

BRL-2 predates the use of tandem shaped charge warheads. The armor was finished before 1984 (when the M1IP entered service), the first Soviet tanks with Kontakt-1 ERA were fielded in 1983. The first NATO missiles with tandem warheads also entered service after the M1IP (BGM-71E TOW-2A: 1986, MILAN-2T: 1991, HOT-3: 1998, etc.).

 

The more reliable values (CIA estimates, values included in an article in a US Army magazine) I've seen suggest a hefty increase in protection against (single stage) shaped charge warheads: i.e. 900 mm instead of 700 mm steel-equivalent protection.