StuG III Thread (and also other German vehicles I guess)

[SH_MM]

18 hours ago, Scav said:

I've seen that and the one other document, but I've seen good counter arguments backed up with measurements on the real thing, I'm still mostly on the fence, though I think it's hard to argue with physical thickness measurements.

 

Do you mean the same "physical measurements" mentioned by heretic88 about five pages ago, which only focus on the gun mantlet, assume that it is completely made of armor-grade steel and not hollow at all? That's not reliable, just like the "solid titanium trunion of the Leopard 2, which doesn't exist. I've never seen any measurements of the actual M60A1 turret frontal armor aside those mentioned in the Soviet reports.

 

The turret cheek armor seems to be ~100 mm thick at most (not accounting for slope), just as written in the Soviet reports.

 

 

 

 

 

 

18 hours ago, Scav said:

Still, it would seem odd to me that the M60A1 with it's ~10t higher weight would only achieve the same (rough) protection as the leo 1 on t he turret....

 

The weight difference between the turrets is much less than 10 tonnes. Add to this different profiles + armor technology (cast steel is less effective than normal RHS, spaced armor formed by rolled steel plates is more effective than RHS) and you got your explanation.

 

18 hours ago, Scav said:

I don't really get how they come to the conclusion that the hull is vulnerable to 100mm AP at 750m for the M60A1, same with the figure for the normal M60

 

Because in reality steel hardness and normal distributions in protection and penetration performance matter. The BR-412B and BR-412D with their blunt-shaped tips managed to retain most of their performance against sloped armor. The upper hull front of M48 Patton (110 mm at 60° = 220 mm LOS) was vulnerable to blunt-tipped versions of 100 mm AP rounds, when the impact velocity was in the range 880-900 m/s. The M60A1's hull armor is thinner but slightly better sloped (228 mm LOS).

 

 

This is a ballistic limit according to Soviet criteria, meaning that 75-80% of all rounds will manage to penetrate the armor at this velocity. From the US perspective - caring about the protection - another criteria would be used, as you don't want to stop only 20-25% of all rounds at the desired range, but a reasonable amount (75-100%). That is why the ranges for protection are larger than the ranges for penetration of the same target in certain instances.

 

18 hours ago, Scav said:

As for the hardness, IIRC the early M60s had that, but the later ones had better steel in the ~260BHN region. 

 

Steel hardness was changed in 1978 for the M60A3, the M60A1 production ended around the same time. Most likely all M60A1 tanks were made with the softer steel. The Soviets (for most of their tanks, but the T-80 is apparently an exception) and the British used cast steel with a hardness of 260-280 HB, which supposedly was 5-15% weaker than RHS according to Soviet sources. German sources say that cast steel was "up to 20% worse" (20% more armor required to reach the same protection level) than RHS, similar statements are made by Sweden (cast steel being 10-20% worse than RHS).

 

The Leopard 1A3 as mentioned by Wiedzmin uses steel plates with a hardness 301 HB and 370-410 HB for the frontal armor,  up to 490 HB for the side armor plates and 260-300 HB for the roof armor. So there is quite a significant difference.

 

16 hours ago, Xlucine said:

Only 5 degrees of protection for the welded leo 1 turret? That's very narrow, M60 and chieftain were +/- 22.5 degrees IIRC

 

The Chieftain was designed with a 45° frontal arc (±22.5 degrees), the M60A1 wasn't. Its armor relied much more on slope in the horizontal plane, very similar to the welded turrets of the Leopard 1 and Leopard 2K/PT. IIRC it was designed with a protected frontal arc of 30° (±15 degrees) or smaller.

 

59 minutes ago, heretic88 said:

Also do not forget the soviet evaluation about M-60A1 protection. They clearly state that from head on, the M-60 is fully immune to even 115mm APFSDS...

 

As Wiedzmin already stated, the Soviet reported that the "mantlet and cradle" provide protection against spall and bullets only, while not stating anything about the mantlet surviving 115 mm APFSDS rounds. You keep beating the same statement and ignore the fact that the same article from Andrei actually lists the gun mantlet as a weakspot!



 

So the Soviets, who actually captured a M60A1 found the mantlet to be badly armored, but they must be wrong, because someone on WarThunder forums measured the exterior (!) without knowing anything about the composition (RHS vs mild steel, hollow or solid) of the mantlet...

 

And btw. that the turret front at 0° could be penetrated "at a close range" by 100 mm, 122 mm and 115 mm projectiles doesn't mean that it is immune to these and also doesn't mean that this range is identical for all these rounds.

[Scav]

33 minutes ago, SH_MM said:

Do you mean the same "physical measurements" mentioned by heretic88 about five pages ago, which only focus on the gun mantlet, assume that it is completely made of armor-grade steel and not hollow at all? That's not reliable, just like the "solid titanium trunion of the Leopard 2, which doesn't exist. I've never seen any measurements of the actual M60A1 turret frontal armor aside those mentioned in the Soviet reports.

I was in-fact talking about the mantlet yes, and there's been measurements made in a pretty professional manner:
https://forum.warthunder.com/index.php?/topic/371226-id-0059205-16jul2017-m60a1-gunshield-and-mantlet/
Even if it's normal cast steel (which it probably is) that's a lot of steel and a lot of LOS.
 

As for the trunnion of the leo 2, I know the leo 2K had a hollow one and the leo 1 before it, but I find the difference in weight for the gun assembly with and without mantlet too much for the mantlet alone.

Going from 4290kg with mantlet to 3100kg without..... unlikely it was just the mantlet.
 

33 minutes ago, SH_MM said:

The turret cheek armor seems to be ~100 mm thick at most (not accounting for slope), just as written in the Soviet reports.

Don't know about the cheeks, they're cast and go lower the further up you go so it really depends on where you measure.
I don't think that's going to reach 350mm across the entire fron though.
 

33 minutes ago, SH_MM said:

The weight difference between the turrets is much less than 10 tonnes.

Oh, I was talking about the entire weight, sorry.
 

33 minutes ago, SH_MM said:

Add to this different profiles + armor technology (cast steel is less effective than normal RHS, spaced armor formed by rolled steel plates is more effective than RHS) and you got your explanation.

Yeah, though there's other differences that might account for a lower weight too, the leo 1 engine is quite heavy, not sure what the M60s one is like.
 

33 minutes ago, SH_MM said:

Because in reality steel hardness and normal distributions in protection and penetration performance matter.

Oh I know.

 

33 minutes ago, SH_MM said:

The BR-412B and BR-412D with their blunt-shaped tips managed to retain most of their performance against sloped armor.

Most as in?
BR-412D doesn't even seem capable of 240mm so there's no way it could penetrate 108mm at 64-66°, both will lack severely against angles even compared to APDS (2nd gen).

 

33 minutes ago, SH_MM said:

The upper hull front of M48 Patton (110 mm at 60° = 220 mm LOS) was vulnerable to blunt-tipped versions of 100 mm AP rounds, when the impact velocity was in the range 880-900 m/s. The M60A1's hull armor is thinner but slightly better sloped (228 mm LOS).

That's PB though, so only at PB could they penetrate the M48 hull, M60A1 hull is significantly better.

 

33 minutes ago, SH_MM said:

This is a ballistic limit according to Soviet criteria, meaning that 75-80% of all rounds will manage to penetrate the armor at this velocity. From the US perspective - caring about the protection - another criteria would be used, as you don't want to stop only 20-25% of all rounds at the desired range, but a reasonable amount (75-100%). That is why the ranges for protection are larger than the ranges for penetration of the same target in certain instances.

Yes, there is the question of how they got this estimate, according to the guy I'm talking to they guessed the performance of 100mm AP at 250-260mm without taking into account the shells would degrade in performance at increasing angles, they also had a simplified model.
I've asked him for the source, hope he'll respond today.

 

33 minutes ago, SH_MM said:

Steel hardness was changed in 1978 for the M60A3, the M60A1 production ended around the same time. Most likely all M60A1 tanks were made with the softer steel. The Soviets (for most of their tanks, but the T-80 is apparently an exception) and the British used cast steel with a hardness of 260-280 HB, which supposedly was 5-15% weaker than RHS according to Soviet sources. German sources say that cast steel was "up to 20% worse" (20% more armor required to reach the same protection level) than RHS, similar statements are made by Sweden (cast steel being 10-20% worse than RHS).

 

The Leopard 1A3 as mentioned by Wiedzmin uses steel plates with a hardness 301 HB and 370-410 HB for the frontal armor,  up to 490 HB for the side armor plates and 260-300 HB for the roof armor. So there is quite a significant difference.

Yeah, there is a significant difference, though the LOS is still quite high, even if you take 15% off that, it should still stop 100mm AP on a lot of the surface area for the turret.
 

33 minutes ago, SH_MM said:

As Wiedzmin already stated, the Soviet reported that the "mantlet and cradle" provide protection against spall and bullets only, while not stating anything about the mantlet surviving 115 mm APFSDS rounds. You keep beating the same statement and ignore the fact that the same article from Andrei actually lists the gun mantlet as a weakspot!

In what manner did they consider it a weakspot though?
Obviously a hit here would disable the cannon anyway.

[Scav]

Not sure if you guys have seen more of the document:
https://imgur.com/a/vz1AA

Seems to me that the turret was simplified somewhat, they also used an estimated BR-412B and a 50% penetration metric.

 

If you have questions, I'll ask the person that gave this to me, he knows a lot more about this than I do and has spent a long time on figuring it out, needless to say that the M60A1 is a very complex tank in terms of armour protection and it doesn't help that the penetration/protection standards vary depending on the source.

Not to say I'm convinced either way, but I think generalising the turret as equivalent to the Leo 1A3 turret isn't entirely correct.

 

[Molota_477]

I just curious on one thing, where can enquire such documents? 

[Scav]

1 hour ago, Molota_477 said:

I just curious on one thing, where can enquire such documents? 

Depends, some can be found readily on the web, some you need to ask people who have copies of them, DTIC is a quite interesting platform that has a lot of research on it.

[heretic88]

4 hours ago, SH_MM said:

measurements of the actual M60A1 turret frontal armor aside those mentioned in the Soviet reports.

The turret cheek armor seems to be ~100 mm thick at most (not accounting for slope), just as written in the Soviet reports.

Here you go. 186.95mm. + double slope. Easily above 300mm LOS viewed from the front.

As for the mantlet, weight calculations clearly show that it is impossible to be hollow.

[Scav]

To be fair, I was a bit skeptical at first and I'm not entirely convinced yet.

BUT.
I don't have a counter argument and I've not seen anyone use anything but that document (A & B) to disprove it, from personal experience I definitely don't put all my faith in documents alone.

Atleast documents that seem to be estimations and theoretical.

[Zadlo]

10 hours ago, SH_MM said:

The Soviets (for most of their tanks, but the T-80 is apparently an exception) [...] used cast steel with a hardness of 260-280 HB, which supposedly was 5-15% weaker than RHS according to Soviet sources.

 

Well, that's not in 100% true.

 

The worst quality cast steel used in Soviet tanks has had this range of hardness. The exact type of cast steel used in turrets (in this example - T-72M1 turrets) offers the hardness between 275 and 455 HB.

[Wiedzmin]

8 hours ago, Zadlo said:

 

Well, that's not in 100% true.

 

The worst quality cast steel used in Soviet tanks has had this range of hardness. The exact type of cast steel used in turrets (in this example - T-72M1 turrets) offers the hardness between 275 and 455 HB.

don't know where you get 455HB for serial postwar casted soviet turret, but T-62, T-72 and T-64 uses SBL-2 steel which has hardness up to 277HB(Impression Diameter - 3,65mm) and tensile strength up to 882MPa 

[TokyoMorose]

10 hours ago, Wiedzmin said:

don't know where you get 455HB for serial postwar casted soviet turret, but T-62, T-72 and T-64 uses SBL-2 steel which has hardness up to 277HB(Impression Diameter - 3,65mm) and tensile strength up to 882MPa 

 

I was going to say, 455HB seems pretty incredible for a serial produced cast steel anything!

[Wiedzmin]

T-34 and JS-2 have 440-450 if US metallurgical test correct 

[Scav]

2 hours ago, Wiedzmin said:

T-34 and JS-2 have 440-450 if US metallurgical test correct 

Cast or rolled?
Rolled that would still be quite high.... especially for an early T-34.

[Ramlaen]

http://m.spiegel.de/wirtschaft/unternehmen/rheinmetall-will-leopard-hersteller-krauss-maffei-wegmann-kaufen-a-1240541.html

[Wiedzmin]

8 hours ago, Scav said:

Cast or rolled?
Rolled that would still be quite high.... especially for an early T-34.

cast and rolled. it's not very high,before you ask high hardness not always means super brittle

 

 german panzer IV front plate(30mm) has 600 on outer surface(face hadened) and 418 rest part(core) of front plate, 50mm plate on G model was 500-520HB but these plates often was brittle  indeed

[SH_MM]

On 11/25/2018 at 3:49 PM, Scav said:

As for the trunnion of the leo 2, I know the leo 2K had a hollow one and the leo 1 before it, but I find the difference in weight for the gun assembly with and without mantlet too much for the mantlet alone. 

Going from 4290kg with mantlet to 3100kg without..... unlikely it was just the mantlet.

 

The weight of the gun trunion of a Stridsvagn 122 (Leopard 2A5) is 110 kilograms including the mounting supports.

 

On 11/25/2018 at 3:49 PM, Scav said:

Yeah, though there's other differences that might account for a lower weight too, the leo 1 engine is quite heavy, not sure what the M60s one is like.

 

The MB 838 CaM-500 has a weight of 1,950 kilograms. R. P. Hunnicutt lists the weight of the the M60's AVDS-1790 at  4,700 pounds dry (in case of the M60A1 and M60A2) and at 4,900 pounds dry (for the M60A3). That equals 2,132 kg and 2,222 kg respectively.

 

On 11/25/2018 at 3:49 PM, Scav said:

BR-412D doesn't even seem capable of 240mm so there's no way it could penetrate 108mm at 64-66°, both will lack severely against angles even compared to APDS (2nd gen). 

 

According to "World War II Ballistics: Armor and Gunnery", the BR-412D can penetrate 235 mm of armor steel at 100 meters distance. Adding differences in criteria and steel hardness to this makes it rather possible that it could penetrate 240 mm armor steel at some ranges. But it seems US protection data is based on the BR-412B round with worse performance tested against cast armor only (at least the source is named "TACOM Ballistic Design Data 100 mm APHE BR-412B vs Cast Steel Armor"): so the hull armor protection might been under-estimated unless the US somehow thought that rolled steel plates with similarly low ballistic performance as the soft cast armor used for the turret was desirable.

 

On 11/25/2018 at 3:49 PM, Scav said:

Yeah, there is a significant difference, though the LOS is still quite high, even if you take 15% off that, it should still stop 100mm AP on a lot of the surface area for the turret.

 

The claimed reduction betwen 5-15% reduction in protection is valid for 260-280 HB steel, not the 220-240 HB (which turned out to be only 210 HB during tests of a M47 Patton tank in Yugoslavia). Given that the US military used some of the softest cast armor and that even American authors like R. P. Hunnicutt criticized the poor quality of this steel, it seems likely that it would be closer to the 20% reduction in protection mentioned by German and Swedish sources.

 

Yes, the M60A1 should be able to survive being hit by a 100 mm AP at some places of the turret front, specifically at the better sloped parts - but not everywhere... and thats what matters.

 

On 11/25/2018 at 5:14 PM, Scav said:

Seems to me that the turret was simplified somewhat, they also used an estimated BR-412B and a 50% penetration metric. 

 

The 50% metric somewhat makes sense, it seems to be the standard used by the US military based on numerous other documents. The BR-412B however is an odd choice.

 

On 11/25/2018 at 5:14 PM, Scav said:

Not to say I'm convinced either way, but I think generalising the turret as equivalent to the Leo 1A3 turret isn't entirely correct.

 

Never said it was equivalent, but similar protection when seen directly from the front. The M60A1 has much better hull armor, better turret side and rear armor, arguably a thicker mantlet and it has a larger protected frontal arc. But when seen directly from the front, the protection difference appears to be negible.

 

The Leopard 1A3's turret was apparently tested against 90 mm HVAP ammo with tungsten-carbide core (West-Germany never used simple APCBC for the 90 mm guns of Patton and KaJaPa), which in terms of raw penetration actually outmatches 100 mm AP(CBC/HE) rounds by quite a bit, but may or may not be more suspectible to damage by spaced armor.

 

In general spaced armor was very effective against older ammo, specifically against bullet-shaped rounds with spin-stabilization. The UK was happy, that the L15 APDS for the L11 tank gun of the Chieftain lost only 20% of its penetration against spaced armor arrays (after optimizations), while US tests showed that adding a 1/2 inch thick steel plate spaced in front of a 3-4 inches thick steel target could increase the protection against 90 mm M304 HVAP rounds dramatically (reducing the maximum range at which the armor can be penetrated by 1.500 to 2,200 yards depending on angle).

 

On 11/25/2018 at 8:08 PM, heretic88 said:

Here you go. 186.95mm. + double slope. Easily above 300mm LOS viewed from the front. 

 

Negative. First of all, the measure point is very close to the gun mantlet and gun mounting mechanism, which might be included at this very specific point. Cast turrets have variable thickness, so seeing one specific point having a certain thickness doesn't say anything.

 

Aside of that, the slope won't be enough to reach 300 mm or more. The M60A1's turret front is ellipsoid, the angle of slope is varying by quite a lot. Close to the front of the turret, it is about 45° in the horizontal plane; when moving away from the center of the turret, the physicial armor thickness is reduced and the slope increases up to 60°. The right turret cheek, where the measurement was made, has a much less dramatic slope in the vertical plane; it reaches only up to 16° close to the commander's hatch and is only 10° close to the gun mantlet. The slope in the horizontal plane is varing between 4° (though the 4° is directly next the gun mantlet) and 57° (close to the commander's hatch), with the turret at the location of the measurement point being sloped at something between 44-50°.

That puts LOS thickness at 261-290 mm and this value might be the result of the mounting mechanism for the gun being nearby. You keep forgetting that the 254 mm LOS thickness is the official figure used by the US Army in its internal documents. There is no logic behind prtending that the M60A1 has 300-350 mm KE protection at the turret (with ~400 mm mantlet), given that the US Army itself says that this is incorrect.

 

 

[Scav]

6 hours ago, Wiedzmin said:

cast and rolled. it's not very high,before you ask high hardness not always means super brittle

 

 german panzer IV front plate(30mm) has 600 on outer surface(face hadened) and 418 rest part(core) of front plate, 50mm plate on G model was 500-520HB but these plates often was brittle  indeed

Interesting, didn't think they reached that high, I'm assuming that went down over the course of the war or?
 

1 hour ago, SH_MM said:

The weight of the gun trunion of a Stridsvagn 122 (Leopard 2A5) is 110 kilograms including the mounting supports.

Where did you get that?
I've been trying to find good info on it but... it's hard to get specifics, I also have to point out that the trunnion might've been changed going from 2A4 to 2A5.

If you look at 2A4 pictures from the inside, the trunnion is painted (probably against corrosion) while that doesn't seem to be the case on the 2A5s, if the pain was indeed against corrosion, that means the trunnion on the 2A5 could be made of a different material, not needing the paint to protect against corrosion, titanium would fit in this case.
 

The switch to a different material could be explained by the wedge of a mantlet adding quite a bit of extra mass (and therefore protection), lightening the trunnion could be a reaction to that, ofcourse, that's just speculation.

 

1 hour ago, SH_MM said:

The MB 838 CaM-500 has a weight of 1,950 kilograms. R. P. Hunnicutt lists the weight of the the M60's AVDS-1790 at  4,700 pounds dry (in case of the M60A1 and M60A2) and at 4,900 pounds dry (for the M60A3). That equals 2,132 kg and 2,222 kg respectively.

Odd, heavier engine that produced less HP and wasn't much more reliable if at all?
Was there another reason for it or just a less impressive part of the tank?

 

1 hour ago, SH_MM said:

According to "World War II Ballistics: Armor and Gunnery", the BR-412D can penetrate 235 mm of armor steel at 100 meters distance. Adding differences in criteria and steel hardness to this makes it rather possible that it could penetrate 240 mm armor steel at some ranges. But it seems US protection data is based on the BR-412B round with worse performance tested against cast armor only (at least the source is named "TACOM Ballistic Design Data 100 mm APHE BR-412B vs Cast Steel Armor"): so the hull armor protection might been under-estimated unless the US somehow thought that rolled steel plates with similarly low ballistic performance as the soft cast armor used for the turret was desirable.

I have reason to believe the numbers in WW2 ballistics are wrong, while I do realise I'm about to post a link to the WT forum of all places, I can guarantee you that Conraire and atleast two other people most definitely know what they are talking about as they have done a load of research.

Way more than I have and probably more than the vast majority of people interested in this topic.
 

That said, they're not flawless in their assessments and are still learning (aren't we all?).

 

So, 240mm I find highly dubious, maybe it would reach this against the cast armour of the M60s that had the lower hardness, I'm not entirely sure if the angle plays a role or if lower hardness is always xx% worse.

Still, I don't think this picture is entirely wrong:

Spoiler

Remarkebly, an SB picture that doesn't seem too far off, obviously, the turret ring isn't ever going to reach 254mm but the rest seems plausible.
 

1 hour ago, SH_MM said:

The claimed reduction betwen 5-15% reduction in protection is valid for 260-280 HB steel, not the 220-240 HB (which turned out to be only 210 HB during tests of a M47 Patton tank in Yugoslavia). Given that the US military used some of the softest cast armor and that even American authors like R. P. Hunnicutt criticized the poor quality of this steel, it seems likely that it would be closer to the 20% reduction in protection mentioned by German and Swedish sources.

Yeah, then in that case 20% does indeed seem more likely, I do wonder how exactly the tests were performed though, I've seen some sporadic mentions of cast armour deficits not being as noticeable at higher obliquities, is there any truth to that?
 

1 hour ago, SH_MM said:

Yes, the M60A1 should be able to survive being hit by a 100 mm AP at some places of the turret front, specifically at the better sloped parts - but not everywhere... and thats what matters.

True, but technically even a leopard 2A6 wouldn't survive a 100mm AP to the underside of the wedge if it bounces down into the hull, while I know that's a pretty weird thing to bring up, what I'm actually trying to ask is: do we know the criteria for what they considered a "penetrating hit"?
I've started to wonder a lot more about this after I've been reading the Swedish powerpoint on the trials, in their renders of the tanks you can see they only colour some areas and probably consider the others "inert", yet we don't get that info on their charts, same with the area around the mantlet for the 2A5 proto, there's small slits that seem vulnerable, was that intentionally "calculated" or just an artifact of the way they did their simulation?

Same goes for the leo 1A3 turret, though it does seem to have a slightly more "homogenous" armouring of the front.

 

I'm waiting for new measurements some people were going to do on the M60A1 turret, the angles don't seem that easy to get right just from drawings alone.

 

1 hour ago, SH_MM said:

The 50% metric somewhat makes sense, it seems to be the standard used by the US military based on numerous other documents. The BR-412B however is an odd choice.

Yeah, IIRC, army standards were the (in)famous 50%, while Navy seems a lot more like the Russian standards (75-80% or something).

Kinda curious as to how much the values would differ if they used different standards.
 

1 hour ago, SH_MM said:

Never said it was equivalent, but similar protection when seen directly from the front. The M60A1 has much better hull armor, better turret side and rear armor, arguably a thicker mantlet and it has a larger protected frontal arc.

Yes, I agree.
 

1 hour ago, SH_MM said:

But when seen directly from the front, the protection difference appears to be negible.

Yeah and honestly that's something that bothers me, it just doesn't make an awful lot of sense to me, maybe I looked at too many articles praising the armour protection of the M60s or downplaying the leo 1 armour but.....

 

1 hour ago, SH_MM said:

The Leopard 1A3's turret was apparently tested against 90 mm HVAP ammo with tungsten-carbide core (West-Germany never used simple APCBC for the 90 mm guns of Patton and KaJaPa), which in terms of raw penetration actually outmatches 100 mm AP(CBC/HE) rounds by quite a bit, but may or may not be more suspectible to damage by spaced armor.

 

In general spaced armor was very effective against older ammo, specifically against bullet-shaped rounds with spin-stabilization. The UK was happy, that the L15 APDS for the L11 tank gun of the Chieftain lost only 20% of its penetration against spaced armor arrays (after optimizations), while US tests showed that adding a 1/2 inch thick steel plate spaced in front of a 3-4 inches thick steel target could increase the protection against 90 mm M304 HVAP rounds dramatically (reducing the maximum range at which the armor can be penetrated by 1.500 to 2,200 yards depending on angle).

Yeah, I've noticed the different "priorities" or "accents" Germany, US and UK put on armour protection, what I found particularly curious is how the UK in the Burlington Chieftain research basically considered 115mm APFSDS equivalent or "probably" not much better than 105mm APDS.

Spoiler

With spaced armour there's always that random factor at play, or atleast that's what it looks like.

 

1 hour ago, SH_MM said:

Negative. First of all, the measure point is very close to the gun mantlet and gun mounting mechanism, which might be included at this very specific point. Cast turrets have variable thickness, so seeing one specific point having a certain thickness doesn't say anything.

I would agree, we need an entire array of pictures and overlayed onto a diagram to see where exactly it was taken, a single picture doesn't say that much.
 

2 hours ago, SH_MM said:

That puts LOS thickness at 261-290 mm and this value might be the result of the mounting mechanism for the gun being nearby. You keep forgetting that the 254 mm LOS thickness is the official figure used by the US Army in its internal documents. There is no logic behind prtending that the M60A1 has 300-350 mm KE protection at the turret (with ~400 mm mantlet), given that the US Army itself says that this is incorrect.

While that 254mm LOS figure seems to be the most common one for the cheeks , I've not seen any other official document state that 300mm or so is wrong, maybe the 254mm figure is an average across the frontal arc (30-45°?) or just a minimum when looked at from the front.

The mantlet does seem to have more though, I don't think 254mm is entirely correct for the entire turret, the mantlet seems closer to 300-350mm to me.

 

 

Anyway, from a purely frontal attack I guess the 1A3 really isn't that far off from an M60A1 turret in terms of raw protection, but it probably wouldn't stand up nearly as well against multiple hits or heavier shells would it?

Those thin plates seem like they would buckle quite easily even if they defeated the round.

[SH_MM]

6 hours ago, Scav said:

Where did you get that?

 

"12 cm kanon strv 121/122 - Skjuttabeller" by the Försvarets Materielverk (i.e. the official firing tables and technical manual of the 120 mm gun of the Swedish army). The title of the document suggests that the data would be largely valid for both the Stridsvagn 121 (Leopard 2A4) and the Stridsvagn 122 (Leopard 2A5), but the drawings and total weight suggests that the weight data is taken from the Stridsvagn 122.

 

But the 110 kg was wrong, I read the value from the wrong column/line by accident. It might be a lot heavier, the trunion with supports is listed as 595 kg.

 

6 hours ago, Scav said:

Odd, heavier engine that produced less HP and wasn't much more reliable if at all?
Was there another reason for it or just a less impressive part of the tank? 

 

The AVDS-1790 was a much older design that was only used for the M60, because the United States originally focused on different projects (mainly the T95 medium tank) and only went back to using the AVDS (which already had been used in slightly different versions in the M47 and M48 Patton tanks) after these ended unsuccessful. The overall situation is a bit worse considering that the United States were using SAE gross horsepower at the time (i.e. they measured the maximum possible power output in the baseline configuration by excluding any factors such as cooling fans, that would result in a loss of power), while Germany was using DIN-PS according to the standard DIN 70020. When the US switched from SAE gross horsepower to SAE net horsepower in 1972, the power output of all advertised cars was significantly reduced (e.g. the Chrysler 426 Hemi famously engine had  an output of 425 gross hp, but only 350 hp net).

 

The AVDS-1790 is however a robust design that had a lot of unused potential, as seen by the later variants (with up to 1,200 hp net horsepowers) used by Israel and others.

 

6 hours ago, Scav said:

Remarkebly, an SB picture that doesn't seem too far off, obviously, the turret ring isn't ever going to reach 254mm but the rest seems plausible.

 

That is the third revision. The original M60A1 in SteelBeasts had 633 mm at the turret front and 400 mm on the mantlet, because the author assumed that the 254 mm was the physical armor thickness before slope...

http://www.tank-net.com/forums/index.php?showtopic=26578&hl=m60a1#entry618626

 

After that there was an intermediate version, still with way too much armor:

 

But the Leopard 1A3 is also overrated by Steel Beasts...

 

6 hours ago, Scav said:

I've started to wonder a lot more about this after I've been reading the Swedish powerpoint on the trials, in their renders of the tanks you can see they only colour some areas and probably consider the others "inert", yet we don't get that info on their charts, same with the area around the mantlet for the 2A5 proto, there's small slits that seem vulnerable, was that intentionally "calculated" or just an artifact of the way they did their simulation?

 

The Swedish protection analysis is focused on the crew compartment only; everthing outside the crew compartment is not analyzed. I know what you mean with the "slit" in the armor protection, but unfortunately I don't have an answer to that question. Maybe this is accurate and a result of how the armor elements are arranged within the array, but it also could be a minor error in the calculations.

 

6 hours ago, Scav said:

Yeah, I've noticed the different "priorities" or "accents" Germany, US and UK put on armour protection, what I found particularly curious is how the UK in the Burlington Chieftain research basically considered 115mm APFSDS equivalent or "probably" not much better than 105mm APDS. 

 

That might be related to the timeframe. The document is from 1969/1970, when the only 115 mm APFSDS NATO knew off had a steel penetrator with no tungsten carbide. It easily shattered when hitting spaced or sloped armor, while having overall rather low armor penetration (200-240 mm at 2,000 meters against flat steel armor). However the Soviets already had the 115 mm BM3 with tungsten-carbide slug at the tip of the steel penetrator, capable of penetrating 270 mm RHS at the same distance - this was AFAIK the first type of 115 mm ammunition accepted by the Soviet Union, but it was expensive and not exported, so NATO only knew about the all-steel penetrators.

 

[Scav]

1 hour ago, SH_MM said:

"12 cm kanon strv 121/122 - Skjuttabeller" by the Försvarets Materielverk (i.e. the official firing tables and technical manual of the 120 mm gun of the Swedish army). The title of the document suggests that the data would be largely valid for both the Stridsvagn 121 (Leopard 2A4) and the Stridsvagn 122 (Leopard 2A5), but the drawings and total weight suggests that the weight data is taken from the Stridsvagn 122.

 

But the 110 kg was wrong, I read the value from the wrong column. It might be a lot heavier.

Oh, that tabel in the "documents for the documents god" thread?

 

Quote

Eleverbara systemets vikt ............................................................................................. 1165 kg
Vapensköld ................................................................................................................................ 595 kg
Hylskorg .......................................................................................................................................... 24 kg
Eldrörsskydd ............................................................................................................................ 29,5 kg
Krugasejektor .......................................................................................................................... 12,5 kg
Bakstycke vikt ......................................................................................................................... 580 kg
Kil vikt ........................................................................................................................................... 110 kg
Vapenvagga vikt ..................................................................................................................... 595 kg
Framförare vikt........................................................................................................................... 36 kg
Rekylbrom vikt........................................................................................................................... 63 kg

Interesting, I completely forgot about this, from my (limited) understanding of Swedish, "Vapensköld" I think means mantlet, "Vapenvagga" supposedly (asked another person too) means guncradle, I'm asking a Swedish friend of mine to confirm though.
 

1 hour ago, SH_MM said:

The AVDS-1790 was a much older design that was only used for the M60, because the United States originally focused on different projects (mainly the T95 medium tank) and only went back to using the AVDS (which already had been used in slightly different versions in the M47 and M48 Patton tanks) after these ended unsuccessful. The overall situation is a bit worse considering that the United States were using SAE gross horsepower at the time (i.e. they measured the maximum possible power output in the baseline configuration by excluding any factors such as cooling fans, that would result in a loss of power), while Germany was using DIN-PS according to the standard DIN 70020. When the US switched from SAE gross horsepower to SAE net horsepower in 1972, the power output of all advertised cars was significantly reduced (e.g. the Chrysler 426 Hemi famously engine had  an output of 425 gross hp, but only 350 hp net).

 

The AVDS-1790 is however a robust design that had a lot of unused potential, as seen by the later variants (with up to 1,200 hp net horsepowers) used by Israel and others.

Thanks!
Engines really aren't my strongsuit so it's nice to see an explanation

 

1 hour ago, SH_MM said:

That is the third revision. The original M60A1 in SteelBeasts had 633 mm at the turret front and 400 mm on the mantlet, because the author assumed that the 254 mm was the physical armor thickness before slope...

http://www.tank-net.com/forums/index.php?showtopic=26578&hl=m60a1#entry618626

 

After that there was an intermediate version, still with way too much armor:

Yeah I remember that 
Always cracked me up when I saw those pictures...
 

1 hour ago, SH_MM said:

But the Leopard 1A3 is also overrated by Steel Beasts...

Yeah, I agree, I think 250mm is also quite high, though I guess it's possible in some areas.
 

1 hour ago, SH_MM said:

The Swedish protection analysis is focused on the crew compartment only; everthing outside the crew compartment is not analyzed. I know what you mean with the "slit" in the armor protection, but unfortunately I don't have an answer to that question. Maybe this is accurate and a result of how the armor elements are arranged within the array, but it also could be a minor error in the calculations.

This has been bothering me for some time now....

And the more I think about it, the more I'm convinced we'll never know until someone actually involved with the tests tells us.
 

My theory is that the values we have were tested but the colour scheme is more or less based on that but filled in the "blanks" with simulation of material thickness, think Warthunder like penetration mechanics with pixel projectiles.

What I'm not sure about is the graphs where we can see the different "versions" with the B tech version on the left with all the different angles and protection %s and the leo 2 "improved" on the right, are those "only" showing the crew compartment coverage or is that including all the visible armour?

 

2 hours ago, SH_MM said:

That might be related to the timeframe. The document is from 1969/1970, when the only 115 mm APFSDS NATO knew off had a steel penetrator with no tungsten carbide. It easily shattered when hitting spaced or sloped armor, while having overall rather low armor penetration (200-240 mm at 2,000 meters against flat steel armor).

Yeah it wasn't the best, still I think it's complacent or naive to think this "new" ammo type isn't much better or has better potential/ working mechanism than APDS.
I think it's probably still better than APDS against complex targets if they're not too spaced or with too thick layers.

 

2 hours ago, SH_MM said:

However the Soviets already had the 115 mm BM3 with tungsten-carbide slug at the tip of the steel penetrator, capable of penetrating 270 mm RHS at the same distance - this was AFAIK the first type of 115 mm ammunition accepted by the Soviet Union, but it was expensive and not exported, so NATO only knew about the all-steel penetrators.

Yeah, until 1981 where the Iranian chieftains got a kicking.... that was a pretty nasty surprise I think for the Brits.

[heretic88]

21 hours ago, SH_MM said:

Negative. First of all, the measure point is very close to the gun mantlet and gun mounting mechanism, which might be included at this very specific point. Cast turrets have variable thickness, so seeing one specific point having a certain thickness doesn't say anything.

Not really. But it looks like you didnt even check the WT report about the M-60 turret... Thickness gradually decrease from that measure point, as angle increases. Below the right lifting eye, it is still 154-160mm. On the left side, where angle is greater, it is 148mm.

 

Also, about the mantlet, I quote from the article:

"... I have contacted with USMC Museum (https://www.usmcmuseum.com) in order to get some information. I asked them, because they restored M60A1 tank two years ago...

... But also I received very important information from the Museum.

 

“Gunshield is built in two parts, and welded together. The piece is
solid, and there are no cavities within, with the exception of the holes for
the cannon, co-axially mounted machine gun and the secondary gun sight.”

 

 

 

[heretic88]

As for BR-412D, I think the most reliable source is Отечественные бронированные машины 1945-1965 гг:

http://ser-sarajkin.narod2.ru/ALL_OUT/TiVOut10/SuRuPzWg/SuRuPzWg051.htm

[Liberator]

1 hour ago, heretic88 said:

As for BR-412D, I think the most reliable source is Отечественные бронированные машины 1945-1965 гг:

http://ser-sarajkin.narod2.ru/ALL_OUT/TiVOut10/SuRuPzWg/SuRuPzWg051.htm

 this is a calculation formula de Marr.

 

[SH_MM]

14 hours ago, Scav said:

Interesting, I completely forgot about this, from my (limited) understanding of Swedish, "Vapensköld" I think means mantlet, "Vapenvagga" supposedly (asked another person too) means guncradle, I'm asking a Swedish friend of mine to confirm though.

 

Eleverbara systemets - elevation system,

Vapensköld - gun shield (mantlet),

Hylskorg - basket for the propellant stubs,

Krugasejektor - fume extractor,

Backstycke - back part of gun (breech block, etc.),

Kil - wedge lock,

Vappenvagga - gun cradle,

Framförare - the opposing actor to the recoil brake (don't know what the exact term is in English),

Rekylbrom - recoil brake

 

The Vappenvagge should include the trunion, but also the other parts of the cradle, at least if the definition is identical to the German one. I.e. everything orange:

(ignore the spelling mistake)

(Gun cradle of the M256 gun)

 

16 hours ago, Scav said:

My theory is that the values we have were tested but the colour scheme is more or less based on that but filled in the "blanks" with simulation of material thickness, think Warthunder like penetration mechanics with pixel projectiles.

 

AFAIK it is all calculated based on the LOS thickness at these tangles and the performance data delivered by the tank manufacturers without any simulation of materials.

 

16 hours ago, Scav said:

What I'm not sure about is the graphs where we can see the different "versions" with the B tech version on the left with all the different angles and protection %s and the leo 2 "improved" on the right, are those "only" showing the crew compartment coverage or is that including all the visible armour?

 

The graphs on this page are not from Sweden, but part of the documents delivered by Germany (that's why the description of the table is in German). The data should be valid for the complete vehicle surface at the relevant angles.

 

 

 

[Scav]

7 minutes ago, SH_MM said:

leverbara systemets - elevation system,

Vapensköld - gun shield (mantlet),

Hylskorg - basket for the propellant stubs,

Krugasejektor - fume extractor,

Backstycke - back part of gun (breech block, etc.),

Kil - wedge lock,

Vappenvagga - gun cradle,

Framförare - the opposing actor to the recoil brake (don't know what the exact term is in English),

Rekylbrom - recoil brake

 

The Vappenvagge should include the trunion, but also the other parts of the cradle, at least if the definition is identical to the German one. I.e. everything orange:

Thanks, yeah I also confirmed it with my Swedish friend, though he isn't part of the military in any way so he didn't know 100%.

That the "Vappenvagge" also includes some smaller other bits makes sense and would explain the rather high weight, though it does seem like the "trunnion" or gun cradle is indeed atleast more armoured than the proposed 25 + 25 like on the leopard 2K diagram.
Makes sense as I've talked to numerous leo 2 crew some of which told me they "tapped" on the trunnion and thought it didn't sound hollow.

And yeah, these guys do actually know more than the average person as they're very much interested in this kind of thing. 

 

10 minutes ago, SH_MM said:

AFAIK it is all calculated based on the LOS thickness at these tangles and the performance data delivered by the tank manufacturers without any simulation of materials.

Ah, that would make sense yeah, I guess this is the simplest solution and probably the most likely.

 

11 minutes ago, SH_MM said:

The graphs on this page are not from Sweden, but part of the documents delivered by Germany (that's why the description of the table is in German). The data should be valid for the complete vehicle surface at the relevant angles.

Oh, interesting, I was wondering why they seemed to look more German than Swedish (admittedly, they're quite similar languages).

So, if it doesn't take into account the "inert" parts that would be more reasonable, I'm still very confused as to the red graph (in the middle), it doesn't seem to portray C tech as the values are incredibly high for such a small weight difference (55.15t -> 56t).

Yellow seems to match the graph on the right, so B pakette + D-2 wedges, but I'm curious as to the other ones.... perhaps a "C tech" pakette + wedges? Or D-1 and D-2?....

We don't have a lot to go on, I'm hoping you have more info on it so we can figure it out with a bit less speculation :D.

[SH_MM]

1 hour ago, Scav said:

So, if it doesn't take into account the "inert" parts that would be more reasonable, I'm still very confused as to the red graph (in the middle), it doesn't seem to portray C tech as the values are incredibly high for such a small weight difference (55.15t -> 56t). 

Yellow seems to match the graph on the right, so B pakette + D-2 wedges, but I'm curious as to the other ones.... perhaps a "C tech" pakette + wedges? Or D-1 and D-2?....

 

The yellow graph might correspond to the Leopard 2A4 with "D" technology armor (production start in 1991), not the Leopard 2A4 with "C" technology armor (production 1988-1991).

 

I can say that the late Leopard 2A4 turret front with the latest armor ("D" technology) did survive a direct impact from the LKE1 APFSDS fired from 2,000 m distance without the projectile reaching the inner layers of the armor array. This round was later type-qualified as 120 mm DM43 APFSDS (given its 600 mm penetrator length and 1,740 m/s muzzle velocity, it should be able to penetrate about 600 mm of flat armor at this distance). The sources for this is classified, unfortunatley it cannot be shared without potentially getting some people in trouble.

[Scav]

11 minutes ago, SH_MM said:

The yellow graph might correspond to the Leopard 2A4 with "D" technology armor (production start in 1991), not the Leopard 2A4 with "C" technology armor (production 1988-1991).

Well, yellow seems to match the leopard 2 "improved" scheme nearly perfectly, for 700mm it shows 30% protected surface which matches the graph on the right, same for the 600mm protection, it's just above 40% for both.

That's only from straight front though.
I don't think D tech was ever a main armour technology, it seems to be exclusively add-ons, I mean, getting 700mm odd protection out of 860mm LOS seems way too much without adding appliqué.

 

As for C tech, I meant the red graph, it's still too much for the weight difference, but I don't know what else it could correspond with.

 

15 minutes ago, SH_MM said:

I can say that the late Leopard 2A4 turret front with the latest armor ("D" technology) did survive a direct impact from the LKE1 APFSDS fired from 2,000 m distance without the projectile reaching the inner layers of the armor array. This round was later type-qualified as 120 mm DM43 APFSDS (given its 600 mm penetrator length and 1,740 m/s muzzle velocity, it should be able to penetrate about 600 mm of flat armor at this distance). The sources for this is classified, unfortunatley it cannot be shared without potentially getting some people in trouble.

Hm, does it mention wether or not add-ons were used?

While I consider your statements and such quite reliable, you have to understand I don't want to just assume you're correct without evidence, still thanks for the info :).

(that only makes me even more confused tbh)