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Early 1980S Armour Comparisons ?


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On 1/25/2021 at 8:49 AM, methos said:

I would say that is possible, but then again it is only speculation. The question remains whether the US Army believed that the Soviets were going to field an APFSDS round with monoblock penetrator within the relevant time frame.

Previously the XM1 was required to only stop sheated steel penetrators with brittle tungsten alloy cores (i.e. the XM579E4), because the US Army assumed that the Soviets would only field such a round in the mid-1980s.

I think that is more of a "when" not if. They dumped billions into bringing the turret armor of the M1A1 up signifigantly and delivered armor components to the Lima tank plant by early 1988. I suspect development took a few years. On another note  The FGR and UK saw things differntly for some time it seems. 

Was the XM579E4 a WA or WC core? The contemporary Soviet APFSDS were nearly all WC core up until the mid 1980s. 3BM-29  not sure about this round.  

On 1/25/2021 at 8:49 AM, methos said:

 

It is also worth mentioning that during the SAIFV program (hypothetical alternative to the Bradley IFV based on a XM1 Abrams' drivetrain components) the option was investigated to stop a potential 115 mm DU APFSDS round (simulated using the XM774 APFSDS). According to the relevant document, the XM774 was capable of penetrating 189 mm steel armor sloped at 60° (378 mm LOS) at 1,000 m distance. Hence it seems more likely that the "380 mm" figure might be based on the M774 round rather than the M833.

 

That seems reasonable. I was thinking that reference threat could have been measured in flat pen. The M833 does about 380mm at 1km flat. 

For compairison it looks the M744 defeats the HT target at about 1190m/s vs 1020 m/s for the M833. 65 vs 53 m/s V drop. Against the HS target the M774 fails at >~1230m/s vs M833 ~920m/s  (Back of envelope calcs). 

 

On 1/25/2021 at 8:49 AM, methos said:

 

Soviet 125 mm APFSDS such as 3BM-26, 3BM-29 and 3BM-32 probably still could defeat the M1A1's armor at ranges in excess of one kilometer.

 

I am a doubtful on the 3BM-26 I have seen no evidence that it does well against spaced arrays. Even if the M1A1 turret array is somewhat less then BRL-2 target . A round similar to the DM-13 was insufficent at any range. A steel WC slug design even putting it at the rear, out performing that test round or comming close to that seems a bit of a stretch. 

Mayyybe 3BM-29 not sure what the construction is (steel encased DU?, DU slug ?). 3BM-32 almost certantly based on what seems to be true.  

 

 

 

 

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22 hours ago, EasyE said:

Was the XM579E4 a WA or WC core? The contemporary Soviet APFSDS were nearly all WC core up until the mid 1980s. 3BM-29  not sure about this round.  

It used an early tungsten heavy alloy core, but in terms of brittleness these were basically on par with WC (but they had a significantly higher density and hence improved lethality). The Britsh FVRDE also considered using such early tungsten alloys for APDS rounds.

The XM579E4 was worse than the German 105 mm APFSDS for Rheinmetall's smoothbore gun (which used the same penetrator as the 120 mm DM13 with a much larger tungsten penetrator than the XM579); yet in 1974 firing tests, the German 105 mm APFSDS failed to penetrate a target consisting of multiple spaced steel plates (equivalent weight 230 mm along the line of sight) even at 200 meters distance!

 

The XM579E4 APFSDS was likely not much better than Soviet designs against complex targets, hence it was never adopted and development was focused on the XM735 (with enlarged tungsten penetrator).

22 hours ago, EasyE said:

I am a doubtful on the 3BM-26 I have seen no evidence that it does well against spaced arrays. Even if the M1A1 turret array is somewhat less then BRL-2 target . A round similar to the DM-13 was insufficent at any range.

You are looking at the ability to penetrate the armor frontally only; the US trials also included tests against the BRL targets at an angle (negating some of the slope in the horizontal plane) apparently to simulate the requirement for a protected frontal arc.

In these cases BRL-1 and BRL-2 could be penetrated by (some of) the tested rounds at greater distances; BRL-1 for example in excess of 10 kilometers.

 

The 3BM-26 APFSDS was the first Soviet round designed with complex targets in mind; its raw penetration power is also quite a bit higher than that of the M774 APFSDS. I wouldn't rule out the possibility that the frontal arc of the M1A1 remained vulnerable to the 3BM-26 at combat distances...

 

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On 1/28/2021 at 11:57 AM, methos said:

 Yet in 1974 firing tests, the German 105 mm APFSDS failed to penetrate a target consisting of multiple spaced steel plates (equivalent weight 230 mm along the line of sight) even at 200 meters distance!

 

Yikes! What was the LOS distance of the array? 

 

On 1/28/2021 at 11:57 AM, methos said:

The 3BM-26 APFSDS was the first Soviet round designed with complex targets in mind; its raw penetration power is also quite a bit higher than that of the M774 APFSDS. I wouldn't rule out the possibility that the frontal arc of the M1A1 remained vulnerable to the 3BM-26 at combat distances...

I think what ends up mattering a great deal is what the concept of "complex" armor is. IIRC there was a document floating around suggesting  some assumptions regarding a sandwich array of Steel, aluminum, cermaics  etc.  I can see   a 3BM-26 design being rather more effective against such an array due to the stablizing effect of solid material not allowing for the effecient imparting of lateral forces vs a spaced NERA array, like Type B and what we assume is in the turret and hull of the M1 ~1980. 

I agree overall I wouldn't rule out that under some circumstances it could be effective. 

Interestingly in the early 1980s the ammo fired by the USA seems to be more effective against the spaced arrays protecting their tanks, while the Soviet ammo was more effective againsttheir own arrays more comprised of steel.  If defeating their own arrays was the goal...they all nailed it. 

 

Anyhow saw this pic floating around. This seems to be a armor concept that  Dr Manfred Held suspected could be in use by western tanks in the 1980s. 

German thoughts on chobham..JPG

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13 hours ago, EasyE said:

Yikes! What was the LOS distance of the array? 

The total thickness of the armor array was 670 mm. At impact angle 34° instead of 30°, (and with that reducing LOS thickness to 599 mm) it could be penetrated by the 105 mm APFSDS round at 200 m distance.

14 hours ago, EasyE said:

IIRC there was a document floating around suggesting  some assumptions regarding a sandwich array of Steel, aluminum, cermaics  etc.  I can see   a 3BM-26 design being rather more effective against such an array due to the stablizing effect of solid material not allowing for the effecient imparting of lateral forces vs a spaced NERA array, like Type B and what we assume is in the turret and hull of the M1 ~1980. 

At some point of time the Soviets used a special target representing the MBT 80 tank; this was based on public descriptions from Jane's Defence Weekly, International Defence Review etc., so it consisted of aluminum-oxide tiles with an aluminium backing located in an steel cavity. However I don't know if this target was actually used as reference for their ammunition designs or solely used to test if their existing ammunition could defeat it.

There are two targets - a seven layer target and a ten layer target - that the Soviets used for testing (at least) the 3BM-42 Mango and 3BM-32 Vant APFSDS rounds; based on the exterior appearance of them (or what has been claimed to be identical to these targets), they consist of thick steel plates with textolite inter-layers only.

13 hours ago, EasyE said:

Anyhow saw this pic floating around. This seems to be a armor concept that  Dr Manfred Held suspected could be in use by western tanks in the 1980s. 

German thoughts on chobham..JPG

No, this isn't related to Dr. Manfred Held. It is an illustration from Rolf Hilmes' latest book, showing generic "Chobham" armor as used on the Challenger 1 and Leopard 2AV. Obviously this is not correct, but it is a step in the right direction - in his previous book on tank technology, he still insisted that Chobham armor was just ceramic tiles with backing, no NERA at all. Now Mr. Hilmes probably read about Chobham being NERA, but was too afraid to ignore the outdated/fake sources claiming that Chobham was based on ceramic armor.

 

 

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