holes in armor!

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I have just read about perforated steel armor-armor full of holes! I have a few questions about this:- how effective is it against APDS and HEAT? What tank uses it (I discovered it while reading about the AMK 40). How does it work? Could we have had it in WW2? Does slope help or not? Love to hear from you if you have the answers.
 
It was used as the primary armor on the Leopard II tank. The holes are drilled at a sloped angle relative to the expected direction of impacts from the top, and are smaller then the diameter of expected threat sabot projectiles. So when a sabot reaches the holed area, it is subject to asymmetric forces and always meets some resistance, encouraging its own erosion. The end result is that protection per weight improves considerably. How much would depend on the exact details of the incoming projectile, as it always will when considering special armors like this. I've heard 70% resistance for 50% of the weight claimed as an average, I have no idea as to the validity of this claim.
Against HEAT the armor protection is generally reduced, though it depends on the exact hit placement. The point though was the Germans thought AP shot from tanks was a bigger threat then HEAT missiles while fighting on the defensive. Missiles could after all be countered to a considerable degree with counter fire and smoke screens due to the considerable times of flight, while you couldn't do much about a well aimed Soviet AP shot. You also could repair perforated armor easily which was a big plus when fighting outnumbered. The British and Americans disagreed about the threats and so used Cobham which was much more effective against HEAT. Ultimately Cobham was improved in various manners to increase protection from sabots, while the Germans improved perforated armor vs HEAT by filling the holes back in with lightweight composite or similar materials. Other changes were also made in the long run, such as the Leopard II now has that big wedge of spaced armor on the front of the turret.
[/size]This sort of armor could be produced in WW2, or WW1 for that matter, but it is not very realistic for war use. First, it’s only going to work well with fairly thick slabs of armor, thinner plates will loose too much stiffness and yet even most German tank armor simply wasn't all that thick in WW2. It also just requires a vast amount of drilling, and drilling steel armor requires large machine tools and lots of tungsten drill bits. It also simply requires a great deal of time in the manufacturing plant. All three were in short supply during WW2, and drill bits were not as good as they would be in the 1970s.
 
Thank you very much for the info. It at first sight looks like a crazy idea but it ain't crazy if it works! Drilling the holes does seem time consuming, plasma jet cutters? Imagine if we used it in WW2-a Comet type tank with Centurian levels of protection, take that Panther!
 
Just re-read the wiki entry for the AMX 40, frontal armor is 400-450mm RHA equivalent using this technique, impressive for a 40 ton MBT.
 
You know I think I'm not remembering that spec I once read correctly. I think it was in fact ~70% of the weight for the same protection could be accomplished against AP shot. Pretty sure AMX-40 had laminated armor that included a composite component.

Plasma cutters wouldn't work very well for making hundreds of holes in large solid chunks of armor. The max depth they can cut would be a limitation with heavier plates, and while they make fairly clean holes as far as cutting torch systems go its still not nearly so clean as what a drill produces. Also drilling can and is water cooled, reducing distortion of the armor plate heat treatment.
 
Take a look at 'Super Bainite' steel. According to the website, perforated Super Bainite steel is twice as effective as conventional steel armor. In addition it is cheap to make and does not need a specalist plant to manufacture it. This sounds like the perfect material for mass produced armored vehicles.
 
I hope you're aware of the nefarious consequences of having lots of holes in a dreadnought's skin.
 
Arjen said:
I hope you're aware of the nefarious consequences of having lots of holes in a dreadnought's skin.
Click to expand...

No problem, you just would have to make sure, that there's always an even number of holes, so water would
pour in through one and pour out through the other hole ! ;)
But seriously, as Sea Skimmer wrote " The holes are drilled at a sloped angle relative to the expected direction
of impacts from the top" and I think, that for a dreadnought directions of a shell could have a wider range of angles,
than for a tank.
 
Sorry. Couldn't resist.
 
It would be okay on a ship angle wise. If you have a vertical piece of armor, you drill the holes at a downward slope from the top. The only way for a shell to fly dead down the holes would then be if it was fired at an upward angle, which for a ship would mean the shell comes out of the ocean. Flooding issues could be mitigated by tapping the ends of the holes and screwing in some plugs.
However I’d really be a bit surprised if the integrity of thick face hardened plates would hold up to hits by battleship shells after you drilled them full of holes. This is much different material than tank armor made, and delaminating of the hard face was always a concern. It might be okay on cruiser belt and turret armor which was more likely to be homogenous material.
Course the cost of drilling so many holes in thousands of tons of face hardened armor might easily be comparable to the cost of simply making the ship somewhat bigger to hold heavier armor in the first place, hull steel isn't very expensive. Tanks are working under different restrictions with regard to absolute weight and engine power. I think some aircraft armor in WW2 actually was made of a series of thin perforated plates, overlapped so the holes didn't line up, but this was a bit different, a lightweight form of spaced armor used for armor behind the cockpits of fighters.
 
Thanks for that, Sea Skimmer. I think you're right on the face hardened vs. homogenous thing, and of course the time taken as well as the expense.


Wrought iron might be a different proposition for drilling; but even if it were, now we're talking a very different era, with a fairly blunt (2crh or worse) rotating shell moving not much faster than sound when it hits as opposed to a slender (e.g. 8crh or better) unrotated, fin-stabilised one moving three or four times faster. The composition of both shell and armour is thus radically different, the circumstances of the interaction are completely changed, and the perforated-armour effect might not even be operative.
 
I think, another reason, that such an armour wouldn't have been a wise choice for a battleship lies in the
following "..and are smaller then the diameter of expected threat sabot projectiles". But during the battleship era,
the range of threat calibre for a battleship was much larger, than for todays tanks. There wouldn't have been too
much sense in making the armour lighter, but still effective against BB main guns, when the shells of the medium
guns could pass through it undisturbed !
 
It depends on the era of battleship. The early sail-and-steamers faced the same sort of homogenous main battery (albeit of smaller calibre) as their Dreadnought descendants. It was the late 19th Century ships first built as sail was dying out that had a more mixed-battery philosophy. By the time you get to World War 1, the range is so far out that secondary batteries aren't playing a role in dreadnought combat any more.
 
Well, I had the end of that era in mind, the time of WW II, when all Navies, which actually
were building battleships fitted medium artillery again and those guns actually were used in
BB vs. BB fights (e.g. Kirishima vs. USN Washington, Rodney and KGV vs. Bismarck),
not to mention, that often cruisers were amongst the enemies (Scharnhorst vs. DoY, Belfast, Norfolk,
Sheffield, Hood and PoW vs. Prinz Eugen and Bismarck. So the danger of a medium calibre shell
passing through a "perforated" armour would have been quite real, I think.
 
Even a thick slab of armor riddled with holes is still going to breakup medium caliber hits, and the angles prevent hits directly down a hole. Also holes are not likely to increase directly in proportion to the thickness of the plate. They'd remain relatively small. As well the smallest caliber shells like five and six inch generally lacked proper APC ammunition which already made piercing face hardened armor nearly impossible. The problem remains if the armor will work at all against heavy APC rounds. I don't think it would be able to hold together, but I really don't know. Adding toughness was the great feat of warship armoring; it wasn't difficult to merely harden it.
 
On that note, I find it interesting to compare early armourclads which had hard-but-brittle wrought iron on a backing of teak with the later ones carrying compound armour (hard steel in front, softer iron behind), and finally homogenous* face-hardened steel. In all cases, the rule of hard in front, soft behind is followed.




* = homogenous inasmuch as it is produced as a single piece of plate rather than two or more joined together. I agree that the molecular structure is nowhere near homogenous when the process is done.
 
Had a look into Erich Groener "Die deutschen Kriegsschiffe" volume 1. He gives the combination of
steel armour on teak until the Deutschland class (the last class of German pre-dreanoughts) for
battleships and until the SMS Seydlitz for battlecruisers. Don't know if it was practice in British
battleship design, too ?
 
I've got Attwood's book on warship design plus a few DK Brown books at home. I'll have a look this evening, but you may be right. From memory, the teak in RN practice was more a space-filler by that stage than the reinforcement for the main armour that it was in sail battleships.
 
Yes, you may be right. In SMS König Wilhelm, an armoured frigate built in 1869 the thickest part of the belt armour was 178 mm of
wrought iron on 250 mm of teak, whereas in the battlecruiser SMS Seydlitz from 1913 it was 300mm of steel on just 50 mm teak.
Just strange, that for the battleships from the Nassau class onwards no use of teak is mentioned anymore. Perhaps it was used
to compensate for a higher flexibility of the larger, but principally lighter hulls of the battlecruisers ?
 
Back to MBT armor,(please!) does anyone know how effective the Russian combination-K armor was? It is a very simple laminate of Steel-fiberglass-steel. I imagine it is an improvement over HRA steel against AP and HESH but how does it fair against HEAT?
 
Jemiba said:
Perhaps it was used
to compensate for a higher flexibility of the larger, but principally lighter hulls of the battlecruisers ?
Click to expand...


Basically the margin of error in the hull girder and the thickness of the plates required some kind of filler to make sure everything was nice and tight and excluding water. As the margins of error went down people shifted to concrete, as in the USN, or were able to do the task with thin steel plates. In the early days of armor wooden backing was needed to absorb vibration and provide a thick armoring for the plates. It never actually added much resistance to preforation, and none at all with later faced hardened armor. So one wished to minimize backing mass, and used thin armor like STS plate to absorb splinters.
 

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