Monday, 18 June 2018

Mousetrap

The Maus tank that was recovered by Soviet specialists did not sit idle in the Soviet Union. It was picked apart and its components were sent out for study. The armour composition and hull design were carefully studied. It would be a shame to demolish such a rare exhibit, so only the D-25 was allowed to fire on it, with the performance of other tank guns (the Maus' own 128 mm and the Soviet D-10) being only calculated.



"Calculations of the anti-shell resistance of main armour components

The calculations of resistance to shells of the main hull and turret armour components were performed using the Jacob de Marre formula with Zubrov’s corrections based on the practically obtained limit of complete penetration established by firing at the 160 mm medium hardness armour plate with a 122 mm tank shell. The coefficient K was established to be 1700 and was used to calculate the resistance of the components regardless of the thickness, angle of impact, and type.
The results are given in table 5.
The table shows that not all components completely protect the tank from being penetrated with armour piercing shells fired from already existing guns.
The vertical sides significantly reduce the resistance of the armour and they can be penetrated (at angles of 90 and 270 degrees) with the domestic 100 mm gun.

Conclusions
  1. The hull of the German Maus tank, composed from large and thick armour plates, is of no significant interest. The only interesting aspect is the method of connecting armoured plates of large dimensions and thicknesses, which can be used on domestic practice.
  2. The vertical placement of side armour drastically reduces the protection and makes the tank vulnerable in certain conditions.
  3. The large dimensions of the hull and turret, as well as the significant mass of the armour (105 tons) reduce the tank’s maneuverability."
Component
Thickness (mm)
Angle from normal
Calculated limit of complete penetration, m/s
128 mm gun
Vo = 870
122 mm gun
Vo = 781
100 mm gun
Vo = 900
Upper front plate
200
65
No penetration
Vpen = 1200
No penetration
Vpen = 1300
No penetration
Vpen = 1500
Lower front plate
200
35
Penetration
Vpen = 850
No penetration
Vpen = 925
No penetration
Vpen = 1050
Side
185
0
Penetration
Vpen = 655
Penetration
Vpen = 700
Penetration
Vpen = 805
Upper rear
160
35
Penetration
Vpen = 695
Penetration
Vpen = 740
Penetration
Vpen = 845
Lower rear
160
30
Penetration
Vpen = 625
Penetration
Vpen = 700
Penetration
Vpen = 798
Turret front
210
0
Penetration
Vpen = 780
No penetration
Vpen = 830
No penetration
Vpen = 950
Turret side
210
30
Penetration
Vpen = 855
No penetration
Vpen = 920
No penetration
Vpen = 1040
Turret rear
210
12
Penetration
Vpen = 755
No penetration
Vpen = 810
No penetration
Vpen = 925
Tank Industry Herald 5-6 1946, p.26

To give some reference to the velocities, the D-25's sharp tipped shell drops below 740 m/s at about 700 meters and below 700 m/s at 800 meters and the improved blunt tipped shell at about 750 and 1300 meters respectively, so an IS series tank would have been able to punch through the side of a Maus tank from a respectable distance. 

Several interesting points here. One is that the assumption that K=2400 in everyone's favourite table doesn't hold here. The armour in the Maus turned out to be of much lower quality. In this test, armour with K=2030 is referred to as "reduced quality" armour, but the Maus scored even less than that: 1700. K=1700 means that the 160 mm of armour can be penetrated by the D-25 at roughly 2700 meters. 

The second is that the "gigantomania" that erupted when the Soviets encountered the Ferdinand turns out to have been justified. The BL-9 gun firing a 122 mm shell at 1000 m/s would have been able to penetrate the Maus in any place other than the upper front plate.

19 comments:

  1. Super large tracked vehicles belong in strip mines and not on the battlefield. BY the way, could industry officials of deliberately used batches of low quality armor on the Maus because they knew it would never be in combat?

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    1. These were early prototypes and the ironworks involved might well have been new to making plate THIS thick to boot so I find it plausible that the shoddy quality while not entirely intentional was considered acceptable (already to save scarce alloying elements) for what were basically technology demonstrators not meant to be sent into combat.

      Had the design entered serial production, to the abject horror of every industrial and logistical planner, plate quality would presumably have improved already due to the foundries debugging their manufacturing processes.

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    2. I don't mean to be a grammar nazi, but the construction is "could have" or "should have" not "could of" and "should of".

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    3. ...those are valid enough colloquial expressions though? Albeit admittedly I'm not sure Will is using the former quite right...

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    4. The proper contraction is "could've/should've/would've," like "couldn't/shouldn't/wouldn't."

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    5. I confess, I use improper writing etiquette on purpose. And I'll keep doing it until McDonald's brings back Szechuan Sauce.LOL.

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  2. Can't wait to see a certain person arguing that the Maus armor was actually good, and that he knows better than literally everyone else. Beyond that, I think William Sager does have a point, it could just be the case that this was, as a prototype, not expected to see battle and thus not given high-quality armor. It could, however, just be that the Germans didn't have the materials to make good armor at that point, though.

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    1. There's an argument that the poor quality armor was not a design flaw in the tank, but a manufacturing problem. Same argument as for Panthers, which suffered in the field from poor quality in the transmissions and armor. People conflate that with poor design, which misses the point.

      In any case, even if the Maus had the armor it was designed for, it was not unstoppable from the flanks and rear. Given its speed and the handful that could be produced, those shots hardly seem impossible. I'd like to see stats about the 85mm firing at the tracks and road wheels, since driving a platoon of T-34s behind it and pounding the tracks seems both possible and profitable. Then you have infantry crawl under it and place 20 50-pound satchel charges :) Or drop SAP anti-ship bombs on it ... Or ...

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    2. However, I would indeed argue that designing a tank with features that your industry is incapable of handling is indeed a flaw in the design. Its like making a modern tank with a railgun, but then realizing you can only fit enough capacitors to fire twice before recharging for an hour with an inadequate generator. Technology just wasnt ready.

      Also the odds of hitting a Maus with a SAP or AP bomb are relatively negligible unless you drop small bombs in groups, which gives you the problem if theyre gonna do much (50kg would need to drop vertically into the roof to penetrate, horizontal drops would only impact the sides)

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    3. Getting way off-topic here, but ...

      At this point in the war, no one was dropping horizontally from low altitude from this sort of target. Dropping from any sort of altitude makes the bomb arc down to near-vertical from gravity acceleration (aerodynamic drag being a minor component in verticalization).

      I'd use at least a full squadron of Pe-2s carrying 4 or 8 100kg bombs each. Those are dive bombers with reasonably small CEPs and the bombs will hit near-vertically even in low altitude releases. The Western Allies would have to use fighter-bomber attacking in 45 degree dives or such, which are less accurate. Still, the P-47D Thunderbolt could carry essentially the same bombload as the SB2C Helldiver, so you could put a lot of bombs on target. (Tillman and Lawson that F4U Corsairs bombing Japanese positions on the Marshall Islands achieved a CEP of 195 feet, which is a good approximation of the P-47. They achieved 4.5% hits against 50 foot targets. We'll be conservative and say 1% hits on a target the size of a Maus. That's not a totally unreasonable number of bombs if we assume that each fighter-bomber can carry three bombs.)

      Getting a direct hit on a tank-sized target is very difficult, but given the cost of a Maus, the effort is probably worth it.

      Oh, and if you have a sick sense of humor, you have B-17s dropping maximum loads of 250lb SAP bombs or Lancasters dropping blockbusters. I suspect that 12,000lb bombs don't need to score direct hits ...

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    4. For one, P-47s are suboptimal for the job due to dive angle and the low number of bombs used (despite their size). The TBD Devastator (carrying 12 100lb bombs) or a TBF Avenger might be better. However, one can also simply forgo bombs entirely and use rockets such as the HVAR AP rockets used against subs. Coming in from high enough they have sufficient accuracy and hopefully penetration to go through certain parts of the roof (such as air intakes). If you want to go further there was even a post war HEAT warhead for the HVAR rockets, which had a penetration of 263mm at 0°, enough to punch through most parts of the Maus at vertical impact angles.

      Also I would doubt HE bombs, even cookies, being that effective against the Maus (not ineffective but substantially less effective than other tanks) due to the heavy skirt armor covering most of the tracks and suspension elements, giving a Maus a very aerodynamic shape against shockwaves with little to no exploitable pockets where the shockwave might get trapped.

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  3. The obvious tactic for dealing with a maus would be to bypass it. They are almost immobile and cannot control very much terrain.

    WW2 aircraft were really, really bad at knocking out tanks a lot less formidable than the maus.

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    1. I suspect the Maus would of been a lot easier to hit than most tanks. And all that would be needed was to break a track. Because after that it was nothing but the worlds most expensive pillbox.

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  4. A 256 lb. GP AN-M57A1 bomb dive bomb dropped from 5000 ft. would only penetrate about 48mm. Enough to throw fragments into the engine with a hit there but not penetrate the turret top.

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    1. Weren't Tigers flipped over by the Caen bombing? A direct hit isn't required.

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    2. A few. It's not a tactic you can rely upon, especially if you consider the level of effort that went into, say, the Caen or COBRA bombings. The air force wasn't going to do that every day.

      I suspect most of the tank wrecks we see flipped over were pushed over by dozers clearing routes.

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  5. The more I see of Maus stats, the less I am impressed. The IS-4 had almost as good armor protection and yet was 40 tons lighter; and although the IS-4 was deemed to have insufficient mobility by the Soviets causing its production to be terminated after 200-250 units, it was far more mobile than this thing.

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  6. A demonstration that the author doesn´t comprehend how ARTKOM used the De Marre function and developed it´s armor quality data.

    K=2400 is for face hardened / high hardeness armor, which succeeds in breaking up the attacking projectile pretty much completely.

    K=2100 is for armor which doesn´t completely succeed in breaking up the attacking shot. This number may apply to both, high quality RHA, which succeeds in partial break up or reduced quality HHA.

    K=1900 is exceptional quality RHA vs intact projectiles
    K=1800 is average ww2 quality RHA vs intact projectiles
    K=1700 is for underaverage ww2 quality RHA vs intact projectiles (soft armor)
    K=1500 is for very poor quality armor against intact projectiles. -Such as, for example, 45mm high hardness 8-S armor plate (T34 armor plate, originally testet and passed with K=2400 against soviet AP) in soviet trials vs captured 5cm Pzgr39, which couldn´t be broken up due to the presence of a functional armor piercing cap.

    Maus armor plates were not "medium hardness" as claimed, and this casts in doubt any rlevance of tests quoted with 122mm AP against "medium hardness" armor (=NOT!!! Maus plates). Of course, this makes the calculations pretty much of a red herring, too. Instead, Maus armor plates was rather soft (215-240BHN), cause it was from Wh naval grade RHA, not from slightly harder Army grade RHA (similar in quality to thick plate ELEFANT armor, which was also originates from naval armor stock). Naval armor was optimized against equal cal attack (f.e. 15cm, 21cm and 24cm AP for plates 15cm to 24cm thick).
    Naval armor would therefore not possess the same ballistic resistence of Army RHA againts undermatching attack, and owing to the softer hardness, would be at a disadvantage to damage the rather easily breakable soviet domestic AP. It would, however, fail in ductile hole formation rather than plugging.
    Soviet wartime ballistic tables were wrongly calculated. The error was not corrected until after end of hostilities due to lack of projectile tracking equipment. The final, 1973 edition for A-19, used by the Yugoslav army has a terminal velocity of 669m/s at 700m.
    Finally, the german 128mm gun V0=870m/s tabulated here is a FLAK L/61 piece, and not the MAUS´s own 128mm KWK44 L/55, which possessed a V0=920m/s.
    It´s worth noting that the 122mm cannot penetrate the (too thin: 210mm) turret front but the 88mm KWK43 / PAK 43 could obtain at least partial penetration of the 230-240mm turret front.

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    1. The coefficient K=1700 was established for the Maus experimentally. So basically you admit that the Maus armour was "underaverage" quality, and that it doesn't shatter even "easily breakable" Soviet AP? Or are you just writing another tirade about how everyone is wrong and you are the only holder of universal truth?

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