Talk:Chobham armour

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infobox[edit]

there must be some kind of infobox we could add? maybe including users, year, manufacturers ect. (Fdsdh1 (talk) 20:31, 15 November 2012 (UTC))

Well, infoboxes must use some standardised format. I don't think a standard box is available that is applicable here.--MWAK (talk) 06:30, 16 November 2012 (UTC)

Perforated Armour[edit]

Can someone provide some information on what "perforated armour" is? I did a quick search and found nothing particularly enlightening. Currently the link just redirects to the vehicle armour page, which has no mention of it. Bobbis 16:48, 21 Apr 2005 (UTC)

Well, in fact it has :o). But to state the obvious: perforated armour is just that: armour with perforations. To understand the principle applied in its simplest form, imagine a block of steel with perpendicular holes drilled into it, that are smaller in diameter than the penetrator hitting it. If the penetrator hits the area between the holes it has to penetrate the whole of the thickness of the plate - that plate of course being a lot thicker for the same weight now that it has perforations in it. If it hits the edge of the perforation the penetrator will tip, deform or (hopefully) snap. That's one penetrator that won't penetrate. If it snags into the perforation the abrasion will be terrible. And abrasion provides 60% of the protective qualities of any armour even during a normal impact.
Instead of drilling holes into a steel plate you can create a similar structure with perpendicular uranium or tungsten rods, bundled together. Cold tungsten is rather brittle so you'd have to encase it in e.g. titanium tubes.
This is only the principle at its most simple. The protective qualities can be significantly improved by applying materials of different hardness and toughness and by using an advanced topology optimised for the expected penetrator. A remarkable advantage of perforated armour compared to Chobham armour is its vastly superior "multiple hit capability" (i.e. sustainability). When modern perforated armour is hit there's at first a build-up of protection: the addition to the protective mass by the deformed penetrators is at first more important than the loss of structural cohesion! If you keep hitting a Leopard 2A4's frontal armour with a T-80 you'll run out of sabot rounds long before the Leo 2 is knocked out. That's very satisfying from the point of view of the Leopard 2 crew. However if an original M1 was hit by a T-64, after the second hit on the same module its crew was (un)protected by a heap of expensive rubble, only good to make toothpaste from (it's the same stuff).
Perforated armour can also be used to protect LAV's against bullets, but then the thin armour plates have to be really optimised for the bullet calibre.

--MWAK 15:51, 24 Apr 2005 (UTC)

This sounds very much like "spaced armor" from the 1960s, actually.
Indeed such systems were then in development and the principles were implemented in the Leopard 1A3 and A4, the A1A1 in the Mittel and Schwer configuration, as well as the French AMX-32 and 40. These types were therefore much better protected than is often assumed (well, their turrets...). Much what has been described as "spaced" is not of a simple laminate type as would be suggested. --MWAK 09:56, 4 December 2005 (UTC)

http://www.ciar.org/ttk/mbt/papers/ijie01/ijie_25_423.pdf is an interesting paper that looks at the effect of projectiles striking the edge of armour plates. MWAK do you have any references discussing the build-up effect or the composition of Chobham? It might be nice to add a perforated Armour article, or at least add something to Vehicle armour Megapixie 03:56, 13 July 2005 (UTC)

There are no unclassified papers on the build-up phemomenon (which is a freak effect anyway); so it's better not to put it in the article :o). The International Journal of Impact Engineering is an excellent source in general. Also the American Ceramics Society (it sounds so innocent doesn't it? But it isn't all about pottery ;o) can give a lot of information. See e.g. http://www.ceramics.org/meetings/cocoabeach2004/armor.asp. Relevant to the article is especially this abstract:
The drive to develop armor systems for combat vehicles requires improvements in the bonding of ceramic armor to metallic substructures. Current methods that utilize epoxy adhesives provide limited strength and ballistic performance. Reactive multilayer joining offers the novel ability to form strong metallic joints between ceramic tiles and metallic plates at room temperature. Reactive NanoTechnologies’ novel joining technology is based on the use of reactive multilayer foils as local heat sources. The foils are a new class of nano-engineered materials, in which self-propagating exothermic reactions can be initiated at room temperature with a spark, laser or hot filament. By inserting a multilayer foil between two solder or braze layers and two components, heat generated by the reaction in the foil melts the solder and consequently bonds the components. The joining process can be completed in air, argon or vacuum in approximately one second. The use of reactive foils as a local heat source for soldering or brazing eliminates the need for furnaces, speeds up the joining process, and dramatically reduces the total heat that is needed. Most importantly the limited heating of the components virtually eliminates the mismatch in thermal contraction that normally occurs on cooling from soldering or brazing temperatures. Thus large thermal stresses are avoided and large area samples can be bonded. This presentation will begin with a description of the multilayer foils and their use as local heat sources in soldering and brazing. We will then demonstrate their utility in the bonding of two ceramic armor systems, Al2O3/Al and SiC/Ti 6-4. For each of these systems we will first show numerical predictions and IR measurements of heat [t]ransfer. Then we will present shear strength measurements for the joints. The strengths achieved range from 30 to 80 MPa, and are limited by failure in the braze or solder. Finally examples of large scale reactive joints for each of these material combinations will be shown.
It's a public secret that in the late seventies the British used boron carbide and the Americans alumina. Stone age technology by today's standards of course :o). The last ten years, in a desperate effort to lower costs enough to equip even LAV's with an effective protection against RPG's, the USA has tried to mobilise the world's research sources. This could only be done by being less strict about security. Especially through the SBIR-program much has been revealed, among which the fact that silicon carbide is used in vehicle armour. http://www.dtic.mil/matris/sbir/ should be most interesting! Particularly http://www.dtic.mil/dticasd/sbir/sbir012/sba39.html
Should you doubt the claims in the article about recent protection levels: see http://www.fprado.com/armorsite/US-Field-Manuals/abrams-oif.pdf on page 7.

--MWAK 09:11, 13 July 2005 (UTC)

All good stuff.

I've seen some estimates of the M1's protection levels on a couple of forums

But a Chinese webpage isn't exactly the most reliable of sources.

The pages on armour are very fragmented (no pun intended). I thought it might be good to re-structure some of it - i.e. a page on each armour type and a main page with summaries linking off to the other pages. The problem is that it's hard to get a concrete references. I'm currently getting side tracked working on Soviet and early western ATGM's - see AT-3 Sagger,Entac ....

Do you think it would be worthwhile re-organising the pages? It's probably going to take me a couple of weeks at least to finish up the ATGM's - but after that I wouldn't mind helping out.

Megapixie 12:44, 14 July 2005 (UTC)

Allow me to comment. :o)
  1. The first diagram has the principle right: the original M1 armour consisted of three main sections: an outer thinner steel plate; a thicker steel back plate — and in between the alumina (Al2O3). However it pretends to give exact numbers. It fails because it is based on a complete misunderstanding of CMC's. It shows no matrix, no vibration absorber, no oxygen absorber and no expansion space. In fact it reminds me of nothing so much as Wilkins original work of over forty years ago, as if all you needed was some massive Magical Crystal. Such a configuration would literally self-destruct. It also fails to understand the fundamentally modular nature of the system.
  2. The first column of armour equivalence estimates is correct. No wonder: it's the official one. The numbers for the M1A1 and M1A2 are ridiculous underestimations though, unless those of the M1A1 are interpreted as indicating the equivalence of a double silicon carbide matrix, without uranium module. Then you would have a lot of empty space left; a single matrix has a thickness, according to the original SBIR discussion (later partially deleted in the archives :o), of four centimetres. The numbers in the Team Abrams presentation are inches, not feet: a RPG with a nominal penetration of 360 mm steel caused only a hole of about 30 mm deep! Such is the superior quality of the American "eumorphed" silicon carbide composites, so much better than the industrial-grade junk Soviet engineers had to work with. There should be space enough to protect the tank with an equivalence of over a metre against KE and almost double that against HEAT and still remain within a weight limit ensuring 80% reliability (if you have a good maintenance team). Newer composites are in development improving toughness through the use of nanotubes; these should make it possible for the CMC's to really contribute to KE-protection. At present no actually bought KE-rounds can penetrate the M1's frontal armour in its heavy configuration.
  3. However, as said, the system is modular; it's up to the theatre commander to decide what the general threat level is, whether strategic mobility demands outweigh the need for protection. I've been told base commanders often remove the CMC's completely to reduce costs by putting them in protected storage, at the same time reducing general maintenance and fuel use. This would then be the origin of the story that the tank "rings hollow" if hit with a hammer. Certainly it seems to be the cause of the heavy suspension damage during the Iraq invasion; drivers made jumps that would have caused no trouble for the unloaded vehicles they were used to, but now destroyed the suspension elements.
  4. Speaking about ATGW's (nice work you've done!), it should be noted that the penetration of a hollow charge does in fact not scale linearly with its diameter: heavy missiles are a lot more dangerous than is often presumed. So that's the bad news. :o)
And now about the article structure. As it is now, it isn't too bad. Vehicle armour can be used as a sort of general introduction — and we need one, I feel: remember that for most people, especially those of the female persuasion, all this is completely new and utterly confusing. It would indeed be very nice to have a special "Perforated armour" article; but, as you said, it's hard to get good references and it might be harder still to defend the validity of the article if challenged. As it is a subject people have strong opinions about (to say the least :o) perhaps it should be mentioned only in the context of Chobham. For "normal" steel armour we could use RHA and sloped armour. I often get the impression less attention should be given to all kinds of modern developments and more to the basics of ballistical protection, which the average tank enthusiast doesn't seem to understand at all :o).

--MWAK 15:14, 14 July 2005 (UTC)

On closer inspection I believe the Chinese table is an incorrect copy of a more original one with four columns, the second then giving data for the M1 Improved. This seems to be indicated by the wrong number for the weight increase. Many other data would make more sense if seen as estimates comparing the M1 Imp to the M1A1, rather than the M1A1 to the M1A2. It's also notable it's assumed the replacement ceramic is titaniumdiboride, apparently inspired by reports about the LAV-programme in the mid-eighties. It's certain titaniumdiboride modules were made, but their very high cost makes it doubtful the entire M1-fleet was refitted with them.--MWAK 18:11, 14 July 2005 (UTC)

Absolutely no scientific reasoning behind this article. Oh, and non of the M1 variants use Chobham as this is a British invention which has never been made available to them.

Is there not even a tiny bit of scientific reasoning present? ;>) Regarding your second claim: it all depends on what you call "Chobham". Since the early seventies there has been close cooperation between the British and the Americans in this field.--MWAK 09:35, 26 April 2007 (UTC)

A person sent to me an e-mail, some years ago, that perfurated armour is did as a lot of holes obliquos in the armour.Then comes another plate, without any holes.Being "/" a hole and a "*" normal material, a perfurated armour is such as this: */*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*Agre22 (talk) 13:14, 26 August 2008 (UTC)agre22

Well, in your diagram, the plates themselves are oblique (possible, but not relevant to the principle), not the holes. Also, if you let one plate cover the holes of the other, it would be benificial to have holes in that plate too, just in another position.--MWAK (talk) 06:21, 27 August 2008 (UTC)

Removed last paragraph under 'applications', I have never read such rubbish based on OR, the French followed the British and use a titanium-tungsten system, Dorchester Armour isn't being 'fazed out' if anything the opposite, armies around the world have rushed out to copy it, as an example the Germans and French have dropped spaced armour in favour of the above. Finally to top it off not a single citation either. Why someone would come onto the Chobham Armour entry and push 1960's spaced armour is beyond me and has no place in this article. Twobells (talk) 14:14, 29 June 2012 (UTC)

An error?[edit]

" The effectiveness of Chobham armour was demonstrated in the first Gulf War, where no Coalition tank was destroyed by the obsolete Iraqi armor. "

I know this does not make sense, and I can think of no appropiate word to replace the second 'armour'. Perhaps someone would like to fix?

It sounds a bit silly :o). "Tanks" might well do.--MWAK 08:09, 7 February 2006 (UTC)

Or "ordnance". Gdr 22:22, 7 February 2006 (UTC)


"armor" is sometimes used as a shortened form of "mobile armor" (which is to say, tanks or other armored fighting vehicles). Here it is clear that the author meant Iraqi tanks. TTK 05:55, 8 March 2006 (UTC)
I forgot to thank you, once I discovered your contribution here, for the enormous amount of work you have done in the past to make available information about this subject to the larger public!--MWAK 20:42, 11 May 2006 (UTC)

One could also say "obsolete Iraqi AFVs" (for Armored Fighting Vehicle) or "fighting vehicles", or "landcruisers" (which would be a rather dated and British term) or simply list the nomenclature of the Iraqi armor involved. —Preceding unsigned comment added by Woerkilt (talkcontribs) 04:51, 27 February 2009 (UTC)

Effect of sloped armor[edit]

The article seems to operate on the assumption that the only advantage to sloped armor is the chance of deflection. That's not the primary advantage. The advantage is simply that the steeper the angle of the hit, the more metal a penetrator has to through in order to breach the armor. As a rule of thumb, every 30 degrees off the perpendicular effectively doubles the amount of armor that has to be penetrated. And so while having flat-sided armor may be an advantage against HEAT rounds, it's a significant disadvantage against kinetic penetrators.

Well — aside from your rule of thumb, which is simply incorrect — you make the common mistake to forget that although angling implies that a longer stretch of armour has to be penetrated, this offers no weight advantage, simply because the angled armour plate has to be proportionally longer. See sloped armour.--MWAK 05:46, 24 September 2006 (UTC)


As applied to most armoured vehicle design below Main Battle Tank level the sloping of the armour is usually applied in conjunction with reducing the thickness of the metal so as to provide the same protection at lower weight with the primary objective of improving performance and mobility; this was a feature of the German half tracks of WWII from which all modern light armoured fighting vehicles have been developed today. The effectiveness of their light armour and greater mobility compared with that of Allied types at the time was profound. Whilst sloped armour can provide some deflection properties these are slight at best. Where deflection does occur against armour it is mostly due to the projectiles own energy being transformed by its momentum in finding its path blocked by impenetrable armour, the unspent energy has to go somewhere.86.27.129.157 (talk) 22:32, 11 October 2008 (UTC)

No, you are mistaken: the benefit of sloping resides in two mechanisms: a better weight efficiency in enveloping the armour and deflection effects. "Reducing the thickness of the metal so as to provide the same protection at lower weight" does not work as such, because, as I stated above, the plate has to be proportionally longer. As it happens, the deflection effects are relatively larger for lighter projectiles, and therefore more relevant for light AFVs. The superiority of German light armour in some phases of the Second World War was due to a more effective tactical and operational use, not to their sloped armour array, as the opposing armies also applied the principle extensively in their vehicle design.--MWAK (talk) 13:31, 27 February 2009 (UTC)

Chapter: "Effectiveness"..[edit]

Everything writen under here is false. 1st, armored vehicles and MBT's were lost in both 91 and 03 and to ATGM's, ROCKETs and Grenades and KE-weapons, including M1's and Challengers. Also this story about the punctured sideskirt M1 is bogus too, it was no tandem warhead, just your common PG-7VL or VM, and this with 330 -> 550 RHA penetration is far cry from the PG-7VR of which none of have ever been encountered in Iraq, infact only know use of this round has been from Checnya and even from there theres been just few photos of this in use.

Well, it's not the best section of the article ;o). The main point however is this: no existing RPG can easily penetrate the Chobham armour proper, i.e. the ceramic tiles. The silicon carbide composite used has a mass efficiency of over 25. A typical double layer configuration would have the equivalence of about 1000 RHA against hollow charges. A RPG-7, whether it has a tandem warhead or not (no, it will not "pre-shatter" the tile), will probably not penetrate even a single layer. But only a part of the vehicle is protected by Chobham.--MWAK 12:23, 11 November 2006 (UTC)
  • Only 1 Challenger2 has been destroyed......It was a "blue on blue" incident. —Preceding unsigned comment added by 86.129.37.181 (talk) 16:18, 8 October 2007 (UTC)

Pics/Diagrams?[edit]

Any pics or diagrams? I'm interested in seeing what this armor looks like/how it works. Maybe an animated GIF of a round penetrating and being deflected/disrupted by the armor? Shrumster 17:02, 30 January 2007 (UTC)

The pictures available are classified and/or copyrighted. The assemblage looks like what it is: a metal framework holding ceramic tiles. When there is a metal face plate, the entire assemblage looks like a metal plate. The heavy armour modules look like removable metal boxes, because they are contained in these. Should you open them, the topology then visible isn't easily described and strongly varies among types. Most published diagrams in the popular literature are rather simplistic and deceptive. Some are downright nonsensical. Especially the terms "layer" and "rod" have confused many artists, apparently not having got a clue how they should be interpreted :o). Anyone is invited to go to http://63.99.108.76/forums/index.php?s=5994548d9d786158a232a99ba6583369&showforum=8 and make a nice drawing of the typical penetration effects, basing himself on the pictures shown in the various pdfs made available through this site. --MWAK 08:35, 31 January 2007 (UTC)

Plastic Armour[edit]

Does anyone know if there is a relation to the second world war era Plastic armour, Chobham style armour can't have arrived out of no where and the earlier Plastic armour is similar in concept in being fine but tough granules kept in shape by a matrix. KTo288 13:59, 10 August 2007 (UTC)

It would indeed not be incorrect to say that Chobham is directly derived from development lines started in the forties.--MWAK 17:27, 10 August 2007 (UTC)
Does that double negative mean yes?KTo288 09:58, 11 August 2007 (UTC)
Yes :o).--MWAK 18:24, 11 August 2007 (UTC)
ThanksKTo288 21:02, 11 August 2007 (UTC)

Rampant speculation[edit]

This article is full of opinion and random hypotheses which aren't sourced. Wikipedia is not a place to speculate on things. Chris Cunningham 17:39, 25 August 2007 (UTC)

Ah, you are communicating. Good ;o). Now to business: the accusation of original research is a very serious one and should not be lightly made. Are you very sure you have the expertise to correctly identify any "opinion and random hypotheses"? Obviously the article needs inline references — putting them in is simply a very time-consuming process, the main reason they aren't there — but most of the content is very basic. Could it be that you have concluded, after reading popular accounts that the composition of Chobham Armour is "classified", that the entire principle of ceramic armour is some great undisclosed mystery? This is far from true, I assure you. I will start adding references — obviously I've been waiting for this — but there will remain a narrative gap between the very technical papers and the implicit knowledge they assume any reader to possess already.--MWAK 18:36, 25 August 2007 (UTC)
Well, yes. The lack on inline citations is exacerbated by the use of phrase like "it is probable that". It's also quite chatty; that "bit of a mystery" thing should be removed, because how a hairdryer works is a "bit of a mystery" as well. Chris Cunningham 08:57, 26 August 2007 (UTC)
In that case we will increase the level of formality — and of course the process of adding citations is far from complete :o). I'm not sure what you mean with "chatty" exactly. As far as I can see there are no sentences without informative content present and the account is quite bone-dry as it is; but perhaps you're an engineer or physicist and correctly perceive that a more quantitative approach would be able to perfectly describe in a single formula what a thousand words fail to express. Should you want to add a quantitative analysis, this would of course be most welcome; nevertheless it should be remembered that most readers would be unable to understand it and need a purely qualitative treatment also.--MWAK 13:34, 26 August 2007 (UTC)
Well, put it this way: what does the phrase "the exact nature of the protection offered is sometimes presented as a bit of a mystery" add to the article? It's obviously not from a source ("The BBC reports that Iranian weapons researchers have declared the level of protect offered by Chobham armour to be 'a bit of a mystery'"), and it is also obviously not going to be much of a mystery after one reads the rest of the paragraph (which somewhat demystifies it), so it would seem that the clause is both irrelevant and unwanted. Removing it increases the sourced:unsourced ratio in the article.
The second problem (which is really the key one) is that things are constantly phrased as "could be" rather than "is". How something could be composed isn't what we should be discussing. Take this: "To minimise the effects of this the tiles could be made as small as possible, but then the ratio between the area covered by tiles and that covered by the matrix would become more unfavourable, also because the matrix elements cannot be reduced accordingly as they have a minimal practical thickness of about an inch. An equilibrium is usually found at a diameter of about ten centimetres." Why the build-up? Just say that the tiles are produced at 10cm because this is the best compromise. This speculative, arrive-at-a-conclusion phrasing is okay for key points in the article, but it's used all over the place. It's possible that the whole "protective qualities" section could be merged into the construction one after this is corrected because of all the duplication it causes through being separate. Chris Cunningham 14:04, 26 August 2007 (UTC)
There are several issues at stake here. Firstly we are not capable of giving a detailed sourced description of the properties of the actual Ceramic Composite Systems used in the respective MBTs of the world's armies, simply because most of the relevant sources have not been made public as yet. What we can do however is to give a sourced presentation of the present state of the art of ceramic armour in general, while abstaining from the claim that this state of the art is really applied in any actual western tank. Therefore we can only describe such systems as "typical" — given the known state of the art of present ceramic armour technology as reflected by the technical literature — and possibly applied.
Secondly, you are mistaken to call "arrive-at-a-conclusion phrasing" speculative. Speculation is the suggestion of facts; what the text does is to give the known design principles and then logically infere from them the conclusions (of course within a certain assumed factual context). This is far from redundant as neither the principles nor their deductions will be obvious to the average reader. If the text merely stated that tiles are 10 cm wide, the reader wil not be given the insight why this must be so. Why not a continuous ceramic layer covering an entire turret side? This was in fact the original intention for the MBT-70. And when the reader is told why — to prevent extensive damage by a single hit — he still would need to be told why in that case tiles shouldn't be made as small as possible. Might be obvious to you and me — but not to most. Of course we could condense the phrasing: "The typical tile size of 10 cm is a compromise between limitation of impact damage and optimising the tile-matrix framework ratio given a minimal one inch framework bar width". This is shorter and we both immediately understand what is meant. However, this is because we already are acquainted with the subject. To the reader it would probably be a bit of a mystery ;o).--MWAK 16:58, 26 August 2007 (UTC)
While I appreciate that this is a fascinating subject, this sort of thing is why WP:SYN was developed. Composite armour has its own article, and as this is an article for a specific type of composite armour it should refrain from using sources which don't actually refer to said armour to advance an argument. On the tile size thing, I'm coming round to your suggestion that it just needs to be made more concise. Chris Cunningham 08:00, 27 August 2007 (UTC)
Well, though the lead section as yet imperfectly reflects this, "Chobham armour" has of course become a generic term for "ceramic vehicle armour" in general. Should we limit ourselves to its strictest meaning, not even the M1 or Challenger 2 can be said to be fitted with Chobham armour in the narrow sense. Composite armour is a much wider concept so merging the two articles seems undesirable. Should we create a new article "Ceramic vehicle armour" we would be forced to begin this with "Ceramic vehicle armour, commonly known as Chobham armour..." — but if "Chobham armour" is the common name, it should in principle be the article title.
As the concept is general, I tried to give a general treatment of ceramic armour technology. I fail to understand what special argument I could be advancing by this. Obviously this would be different if Chobham armour were such a complete mystery that it would not even be certain that it was ceramic armour — for then the emphasis on this armour type would be biased. However, again the lead section is as yet incorrect: we have good official, public and published information on the basic properties of Chobham armour in the narrow sense.--MWAK 18:29, 27 August 2007 (UTC)
The intro edits are good. I'm going to de-tag this and see what else I can do to help out. Thanks for working so diligently on this. Chris Cunningham 08:44, 28 August 2007 (UTC)

Further work[edit]

No thanks. I'll continue being diligent by first of all adding the references you indicated as the most necessary :o). Your restructuring of the article is very reasonable; only I feel that it would be more "logical" to first give the general physical principles involved — in an expanded section — and only then present the structural properties. I'll also try and create a short "Development" section, as an introduction to the subject.--MWAK 10:56, 29 August 2007 (UTC)

"No thanks"?
I'm not sure that we can get away with explaining the protection factor first, again due to the angle of not trying to teach content. We should first describe, then explain things, rather than presenting the problem first. But no reason not to experiment!
The article's looking pretty nice now. Once it's got more inline citations, it can probably get graded as a good article. Chris Cunningham 12:01, 29 August 2007 (UTC)
Sorry, I didn't mean "No, thanks" but "No thanks are necessary". My germanic background got the better of me...I indeed have taught this subject in the past, so that could explain my educational approach of the matter :o).--MWAK 19:09, 29 August 2007 (UTC)

Reference formatting[edit]

Okay, we've got a lot of contextual referencing now. We should move to eliminating redundancy by having a References section containing the full description of the books being referenced (in proper cite tags) and a Footnotes section which contains the page numbers. I'll start doing this. Chris Cunningham 07:56, 4 September 2007 (UTC)

Very good idea! Thank you for your efforts; I myself tend to be a bit lazy and simply copy the whole for each footnote...--MWAK 07:13, 6 September 2007 (UTC)

Leopard 1 "glacis armour"[edit]

Leopard1 cfb borden 1.JPG
Leopard-1-latrun-1.jpg

Such modules are also used by tanks not equipped with Chobham armour; an early less sophisticated steel version of such armour can be seen attached to the glacis of the German Leopard 1.

I'm removing this, until someone can find a reference. As far as I know, the only thing which can be seen attached to the Leopard's glacis is the metal racks for storing the track grousers, seen empty and loaded in the photos here.

I sure hope the article isn't full of other such tidbits. Michael Z. 2007-10-03 22:58 Z


Yes, but the reason the track grousers have the shape they do and are attached at this particular place is that they can function as a primitive perforated armour system :o).--MWAK 07:42, 4 October 2007 (UTC)

Why an M1 Picture?[edit]

Since this is British armour I don't think that the only picture should be of an American tank! Why don't we put a picture of a Challenger 2 up there? —Preceding unsigned comment added by TechnoRat (talkcontribs) 17:26, 24 January 2008 (UTC)

Make that a Challenger 1, I would say :o). But again: it has become a generic name.--MWAK (talk) 08:08, 26 January 2008 (UTC)
Done. --Padijow (talk) 22:21, 13 May 2008 (UTC)

"Structure" versus "Protective qualities" again[edit]

The more I look at this, the more I think that we should be explaining what the armour does before how it does it. I really think the order of these sections would be best swapped. Chris Cunningham (not at work) - talk 23:23, 11 October 2008 (UTC)

Yes, one of the many possible logical orders could be to first discuss the demand made on such armour, then the general qualities which enable it to meet this demand, followed by the consequences for auxiliary structures and finally the way all the components fit together to form a coherent whole.--MWAK (talk) 07:14, 12 October 2008 (UTC)

Time to propose GA?[edit]

Article looks pretty nice now, informative and complete. Think it's time to nominate it as a good article? Chris Cunningham (not at work) - talk 12:44, 13 October 2008 (UTC)

Well, it is informative, but complete? As someone probably having an above average knowledge of the subject, I'd say there are many, many gaps: the Start-class criterion "The article has a meaningful amount of good content, but it is still weak in many areas" is still applicable. The history section is somewhat adequate, but the technical sections are very superficial; they really form but the roughest outline of the content that should be there. Also, obviously, any serious quantification of the main physical principles and material properties involved is simply lacking. If Wikipedia is to be taken seriously we had better abstain from puting the label "good" on texts that any expert would consider simplistic or even childish...Maybe we could uprate it to the new C-class instead? ;o)--MWAK (talk) 08:10, 14 October 2008 (UTC)
Fancy posting an outline of where you think it should be headed, content-wise? Chris Cunningham (not at work) - talk 13:06, 14 October 2008 (UTC)
As said, the present text already is an outline! The desired content is indicated by the implied questions posed by it. If we read the first sentence of the Protective Qualities chapter: "Due to the extreme hardness of the ceramics used, they offer superior resistance against a shaped charge jet and they shatter kinetic energy penetrators (KE-penetrators)", we ask ourselves: "How extreme is that hardness? Are some ceramics harder than others? Is there a hardness variation within a ceramic and would this matter? How superior is their resistance exactly? Superior compared to what? How does it vary with the hardness? Is the same mechanism used to shatter those penetrators? Are jets and penetrators equally affected? Are all jets or penetrators equally affected? What is the relation with toughness? With density? With temperature?" etc., etc.--MWAK (talk) 07:08, 15 October 2008 (UTC)

Protection Levels?[edit]

So what are the actual protection statistics for the Chobham armor? I mean, how much RHA protection would 100mm of Chobham armor equal?--HellraizerofUSA (talk) 22:35, 29 June 2009 (UTC)

Well, there is no such thing as the Chobham armour. Types vary a lot. Also the threat varies a lot: KE is different from HEAT-attack. And then there is the problem of the interaction between the different components: ceramics, foam, metal backing plates. Pure ceramic armour from the seventies would, for a given weight, be a few times more effective against HEAT-attack than RHA. As it was also a few times lighter, for a given thickness the protection would be about equal. Against KE-attack the effectiveness would have been about equal for the same weight, meaning it would be a few times less for a given thickness.
A modern ceramic would be expected to have a protection level against HEAT that is a full order of magnitude better. That means that even a plate of the same thickness would be about ten times as effective than RHA. But its protective qualities as regards KE have not kept up, meaning it would give about the same protection against penetrators as a RHA-plate of the same thickness.--MWAK (talk) 07:21, 30 June 2009 (UTC)

Citatation needed on hardness being primary factor in defeating shaped charge jets[edit]

As pretty much all materials can be treated as a liquid when hit at the speed a shaped charge jet moves (see page on shaped charge) at I don't see how hardness could help. —Preceding unsigned comment added by 188.221.161.189 (talk) 18:31, 31 January 2010 (UTC)

Yes, pretty much all materials. This is why only certain materials are useful for "special" armour :o). The main mechanism, as explained in the text, is that the armour is brittle and fractures, the "shards" destroying the geometry of the "jet". You cannot use hydrodynamics to correctly describe the process. It's a bit more chaotic, so to say.--MWAK (talk) 14:48, 1 February 2010 (UTC)
Hydrodynamic models (models which treat penetrator and target materials as liquids) were the best people could come up with to describe hypervelocity-domain penetration in the 1960's, but we've learned a lot about it since then. The interacting materials are not literally liquids. Characteristics such as hardness, elasticity, and material strength play a significant role in the behavior of hypervelocity penetrations, as evidenced by Anderson's, Lanz's, and Odermatt's recent contributions to the field. Now, that having been said, calling hardness "the primary factor in defeating shaped charge jets" seems like an overstatement, or perhaps a misrepresentation of "surface dwell" (also known as "interface defeat", where penetrator material moves laterally across the face of hard ceramic components for a relatively long time before penetrating into the ceramic). If dwell plays a primary role in Chobham/Burlington's operation, then the claim would be more understandable (though still worded a bit poorly). Producing dwell depends on a number of factors: (1) a ceramic material with high compressive strength, (2) a high quality of bond between the ceramic component and a hard, strong, dense backing component (such as steel, tungsten heavy alloy, or depleted uranium alloy), and (3) hydrostatic prestressing of the ceramic component. Lacking any one of these things will greatly diminish the surface dwell. TTK (talk) 18:19, 3 June 2010 (UTC)

Arguable and non-verified content[edit]

I've read the article several times, but there is much information without citation/verification.

  • The whole article is giving no real hint of the composition of Chobham armour, it is only talking about generall ceramic matrices armour ("Chobham-style armour"). Therefore the article includes a list of ceramics (boron carbide, silicon carbide, aluminium oxide (sapphire or "alumina"), aluminium nitride, titanium boride), but no really quotations which ceramics are used.
  • The article claims that the MBT-70 was protected by silicon carbide. No citation is given. The armour of the MBT-70 is according to serveral other sources, the English Wikipedia article and the German equivalent described as spaced armour (Schottpanzerung (1st generation) in German).
  • The development section includes serveral sentences/phrases which aren't part of the development of Chobham armour and therefore aren't relevant.
  • The usage of Chobham armour in the Leopard 2 is generally denialed in this article. In fact most sources claim that the Leopard 2 uses a special kind of composite armour including Chobham-style ceramic matrices. Encyclopedia Britannica and the German Wikipedia article (based on books written by W. Spielberger, Frank Lobitz, etc.) claim that the Leopard 2 uses a Chobham-style armour. Christopher F. Foss claims in the book "Panzer und andere Kampffahrzeuge von 1916 bis heute" (Illustrated encyclopedia of the world's tanks and other fighting vehicles) from 1977 that [...] at the end of 1976 it came out that the in Great Britain developed Chobham armour was used. The early prototypes [1] [2] used the same type of armour as the Leopard 1A3/1A4, but some prototypes [3], the Leopard 2AV and the production models all have the slab-sided appearance, which is according to the article typical for Chobham/Chobham-style armour (Instead of rounded forms, the turrets of tanks using Chobham armour typically have a slab-sided appearance).
  • The M1 Abrams is according to this article using Chobham armour, although it is told to be a modificated version which includes a DU layer.
  • Ceramic polystyrene foam is mentioned in the text. Polystyrene is not a ceramic foam, it is a kind of plastic. Foamed polystyrene (sometimes known as Styrofoam or Styropor) doesn't have the same potency as a layer of unfoamed polystyrene
  • The article includes several (obvious) false claims about the usage of perforated armour. The Leopard 2 would use a armour system mainly relying on perforated steel plates. How can the Leopard 2 with such a type of armour be having a higher protection level agianst chemical energy than against kinetic energy? Why do other sources (mentioned above) claim the opposite? And why should "Armored Cav — a guided Tour of an Armored Cavalry Regiment", a book about the American tanks, be considered a reliable when it comes to German tanks? Not to forget that the first series produced Leopard 2 already had the slab-sided turret [4].
  • Furthermore the article mentions "[...] the very large procurement, maintenance and replacement costs of those ceramic armour systems not based on the cheap but rather ineffective alumina.". I've never heard about anything like that. How to replace the ceramic tiles? They must cut through the outer layers of the armour and the matrix. What kind of maintenance has to be done? They also would have to cut through the outer laysers of the armour/matrix to reach the ceramic tiles.
  • Imo this article should be renamed "Chobham-style armour" or the content should be reduced to the early M1 and Challenger 1/2.
  • The useage of ceramics in aircrafts is not worthy to mention in an article about a type of tank armour.
  • I've heard that Chobham, which itself is not an official name, is also called Burlington (or somehow affiliated with it). Declassified documents shows that this armour was presented to the FRG.

--Tim.vogt (talk) originally posted 11:37, 28 November 2010 (UTC), reposted by --Tim.vogt (talk) 11:15, 4 January 2011 (UTC)

Concerning the LEOII and perforated armour. Maybe the confusion is because modern armour doesn't consist of a single type of armour, but instead consists of multiple types of armour, each type designed to give a certain "effect". One could suggest that an armour system had perforated armour on the outerside (primarely to defeat Ke rods, and offer some defense against HEAT) backed by composite or chobham armour on the inner side to primarely defeat HEAT and stopping weakened (by the outer armour) Ke penetrators.
So it would be a "both". Jomsviking (talk) 12:03, 3 January 2011 (UTC)
User Tim.vogt had withdrawn his contribution. Though it raised a lot of valid points and pointed out many possible misconceptions, I feel it is best to respect his decision, so I will again remove it for the time being. Maybe your reaction will motivate him to reinsert it or an improved version. Certainly you are correct in suggesting that modern armour packages might use a combination of armour types. It would be more typical to have the ceramic armour on the outside, though, just as with the later M1 systems.--MWAK (talk) 20:47, 3 January 2011 (UTC)
I didn't withdraw anything. I added the section twice (due to some connection troubles) and removed the second one, you later removed the other, which was intented to remain. Btw. the outmost armour layer shouldn't consists of a Chobham like matrix structure, else it would be damaged (not penetrated, but it would lose stability), when hit (even by smaller 30 and 40 mm APFSDS). At least the Challenger 2 has two steel (?) layers bolted on the turret front. --Tim.vogt (talk) 11:15, 4 January 2011 (UTC)
My apologies. I hadn't noticed this or I would have answered sooner. Whether they should or should not :o), on the M1 the outer layers consist of ceramic armour modules. Indeed this makes these susceptible to damage by rapid-fire cannon.--MWAK (talk) 13:34, 4 January 2011 (UTC)
Jomsviking, I personally believe it is a mere missinterpretation. Mostly "perforated armour" is explained as "layers of steel at different angles". In German the term Schottpanzerung or Mehrschichtschottpanzerung is sometimes used to describe the armour of the Leopard 2. This term doesn't have an adequate English counterpart, but imho "laminated armour" or "(mulit)layered armour" would be matching. Schottpanzerung can itself be subdivided into three generations: the first generation (used in MBT-70 and Marder 1A3) consists of spaced steel plates, while the second (used in the Leopard 1A3/A4 and early Leopard 2 prototypes (PT 1 - 17?)) can already seen as "real" composite armour. Although I personally don't really believe that perforated armour is incorporated in this tank, the current article doesn't point out that the Leopard 2 doesn't only rely on it, but also uses other composite armour. The German sources I've read doesn't mention any perforated elements, but instead high hardened steel, ceramics, plastics and rubber. --Tim.vogt (talk) 11:15, 4 January 2011 (UTC)
Tim, sounds reasonable. Regarding the perforated armour on LeoII, I was told by a (danish) tanker that the (some of) armour on the LEOIIa5DK was "a kind of steel with cavities filled with some kind of foam" I translated that into some type of "perforated armour". Now eventhough many internet sites put extreame credibility into the testemony of soldiers/tank crew, I think they lack the material physic knowledge to have a clue about what they are seeing, but that's just an oppinion (not that I am an expert on the subject, though I know enough to know that I don't really don't know anything about it) — Preceding unsigned comment added by Jomsviking (talkcontribs) 11:58, 4 January 2011 (UTC)
Some time ago the Leopard 2A5s of Danemark were upgraded with MEXAS-H applique armour on the hull, i.e. ceramic tiles and a outer steel were bolted on. Maybe he was talking about this? Another explanation might be the usage of tungsten. Tungsten can't be used effectively without a harder bonding structure. According to the German wikipedia tungsten is normally inserted into small holes inside a nickel or steel plate, which later is hardned. The DU-layer in the M1s armour is also using a special structure ("steel encased DU wire mesh").
But how does he get information about the Leopard 2 armour? No tank was licence built in Danemark. And afaik the repairs on the tank armour are done by KMW. --Tim.vogt (talk) 12:36, 4 January 2011 (UTC)
"But how does he get information about the Leopard 2 armour? No tank was licence built in Danemark. And afaik the repairs on the tank armour are done by KMW"
Don't know Jomsviking (talk) 20:26, 4 January 2011 (UTC).
The Danish tanker was basically right :o). Probably someone took the trouble of correctly informing him. Always good for morale, I'd say. Schottpanzerung, though its literal meaning is different, is in the literature used as a synonym of "spaced armour". Even the hardest (armour) steel or nickel is considerably softer than any tungsten alloy used.--MWAK (talk) 13:34, 4 January 2011 (UTC)
That depends on the source and the date. In the 70s and 80s (there were some nice article/books about tanks) the term was used more often for composite armour, nowadays it is more affiliated with spaced armour. --Tim.vogt (talk) 13:51, 4 January 2011 (UTC)
"Schottpanzerung", Doesn't "Schott" mean something like "Bulk head" ("Skot" in danish)? IF true, Maybe that gives an idea of the "Schottpanzerung" as an armour structure resembling that of the compartemensation of a ship? Maybe a distinction to spaced armour, is merritted by the structure not only given more depth to the armour at constant weight (which is basically the spaced armour idea) but, I imagine, that multiple "bulk heads" (plates of armour) made with different hardnesses can play a role in deflecting or tipping a penetrator within the armour "package"??? (or is that far out?) Jomsviking (talk) 20:26, 4 January 2011 (UTC)
That's correct, "Schott" can be translated as bulkead. Schottpanzerung could be determined as "armour with an outer and an inner layer consisting of metal". The Leopard 2 armour is built "inside" the tank walls [5]. As I allready mentioned there are claims of several materials/structures being used inside the armour. I.e. layers of steel (high-hardened), tungsten, the English wikipedia claims titanum would be used, ceramic, plastics and rubber. Imho it is probable that the outermost layers of the armour consits of steel (and rubber or plastic), followed by a ceramic matrix (Chobham-style) which is backed by a tungsten layer, followed by another plastic/rubber/steel composition. --Tim.vogt (talk) 20:49, 4 January 2011 (UTC)
Ohh, my wast knowledge of german! ;) Anyway, concerning the tungsten, which I quess is used for defeating Ke penetrators. Why do they place it at the back, I would suspect that you wanted it at the front?Jomsviking (talk) 22:45, 4 January 2011 (UTC)
As far as I know Tungsten (or DU) itself is not a very good armour material on it's own, since it has a hardness of only some 294 HB (lying in US armor class 1 & 3 for a 1.25 inch thick steel plate [at least in the 90s]). But Tungsten or DU have a very high density, therefore it is used as backing plate in the ceramic matrix, which increases the ceramic tiles efficiency against kinetic energy. I believe that the ceramic matrix is located behind a sequence of (hardened) steel, rubber and/or plastic layers, which should offer at least protection against medium caliber rounds (and maybe even more). But that's just opinion. --Tim.vogt (talk) 10:53, 5 January 2011 (UTC)
Well, pure uranium is rather soft. Therefore it is used in alloys with titanium or nickel, which alloys are as hard as armour steel. Pure tungsten though is extremely hard in itself (2570 HB) and is used in alloys to make it tougher. Tungsten nor uranium are typically used as backing plates; they are difficult to apply in plate form ("heavy armour" has the form of perpendicular rods) and density is not all that relevant for a backing plate. Their alloys would be so hard that they would reflect too much energy and thus increase damage to the tile in case of an impact. It's true that the ceramic armour could in principle be protected by a thick outer layer of steel but modern 30-40 mm rapid fire cannon are so powerful that you would need about 120-150 mm steel to effect this. As the weight of a 55 ton tank turret armour is equivalent to about only 400 mm RHA frontal protection in the first place, you can't afford to apply a third of that weight in the form of conventional steel as it would comprise the entire special armour concept (which was why the Challenger 1 which still used a cast steel inner turret was replaced by the Challenger 2). That mass can be used about three times as effective in the form of perforated armour. The outside of the modern Western tank turret is basically just a thin-walled container. Nor is the outer wall backed by plastics or rubber; while it is true that this could dampen the impact to protect a ceramic tile attached to it, this is irrelevant because there simply are no such tiles: the armour is modular. In the container removable metal boxes are placed with the matrix plates inside. These boxes do not touch the outer wall.--MWAK (talk) 09:03, 6 January 2011 (UTC)
2570 HB? You must be kidding, this value can't be true. You can take a look at matweb where the hardness of pure Tungsten (249 HB, as hard as a medicore steel) and some commercial alloys can be seen. No alloy of the one I checked had a hardness even close to 1000 HB. Hard materials tend to break or shatter (like ceramics), a property which makes them useless as penetrators (Tungsten and DU are used as penetrators for APFSDS/APDS, while the Soviets did/do use some steel parts). And afair density is a important factor for the usefullness as backing plate (I've read this in imo reliable sources and it makes sense in the physical aspects). If you don't believe it is usefull as backing plate, why/and where would you use it? Ceramics itself are pretty hard and can be used for protection against KE (as proven by MEXAS and AMAP). Why would you use such a high-densitity (heavyweight) material if you can use low-weight ceramics instead? Armour thickness doesn't seem to be an important reason.
Regarding the steel (rubber/plastic) composite armour at the front: the Challenger 2 has two rolled steel plates (imo ca. 50 mm) bolted on the turret front. They are pretty easy to see: [6]; Here is a Challenger 2 without bolted on parts (in front of the Bovington tank museum). From the thickness they might be not as thick as required to fully adsorb the impact energy of modern medium caliber APFSDS, but they are told to be high-hardened (they would cause spall, but this would only hit the base armour), they work as disrupting stage. Regarding the ~ (350 -) 400 mm RHAe frontal, you seem to speak of the M1 Abrams (basic model), which didn't have largely superior KE protection than other contemporary tanks (Leopard 1A4 turret ~ 300 mm, T-72 ~ 305–410 mm, T-64 ~335 - 450 mm) and therefore might not be the best example. But: the Chieftain had 380 mm thick frontal steel armour and a weight of some 55 tonnes.
Do you believe that the M1A1 (or the Leopard 2A4) have some 80 cm thick "Chobham armour"-boxes on the turret front or do you support my opinion that other laminated armour is also used? And how to "replace" them (in the case of the Leopard 2 and the M1A1/2 these "boxes" are welded together to the turret/or a "roof" plate was welded upon them)? --Tim.vogt (talk) 14:24, 6 January 2011 (UTC)
Point taken: 2570 is of course its Brinell MPa number, not the HB value. Well, it is still one of the hardest natural elements ;o). Certainly when properly treated. As regards the use of hard materials as penetrators, one should not confuse hardness with brittleness. Tungsten carbide is very hard but was still widely used in AP-rounds, though admittedly shattering was a problem.
When the Americans began to add uranium modules, they openly stated the reason for it: ceramics are less effective against KE-penetrators. I.e. less effective per unit of weight. The main reason for this was that the uranium was given the form of what has been described as a "mesh" or as "rods". So it is a perforated armour system, combining solid parts with cavities. The penetrator must therefore either hit a solid part, being of extreme thickness because the weight saved by the cavities can be concentrated there or travel through several cavities subjected to the edge effect, sloped armour, differential hardness, toughness and density, all this causing abrasion, deformation or breakage. Using heavy metal components instead of only steel or titanium offers the advantages of limiting the armour thickness to better fit a pre-existing tank design (so, the thickness is relevant) and increasing the material differentials. And in general, metal systems are of course a lot cheaper than ceramic tiles. So, unless one is locked in some design path dependency as happened to the poor Yankees, these are better avoided.
As regards the case of the Challenger 2, you made the very plausible suggestion the frontal turret plates might be disruptor elements. However, such might be useful whether there is a ceramic armour present or not and would also function against large calibre penetrators.
When referring to a 400 mm steel equivalence I meant the weight, not the protection level. So a 55 ton tank will have the mass equivalence of 400 mm steel to put on the front of its turret, whatever the system he uses. Dependent on that system the protection levels might vary wildly — precisely the reason to use as least conventional steel as possible.
In the case of the M1 it has been disclosed that the armour package is divided in a ceramic tile system in the front and a uranium mesh system more to the back. Given the advantages made in ceramic armour protection against HEAT-threats, the tile matrices are today likely rather thin. To the best of my knowledge, there has been no official source stating that any Leopard 2 model is equipped with ceramic tiles. It's very confusing trying to interpret all this as a "laminated armour". Real laminated armour-ceramic sandwiches were developed in the sixties but proved to be a failure, the very reason Chobham was such a breakthrough. Certainly the heavy metal really doesn't resemble a laminate; it is not applied in "layers" or "plates" but as largely perpendicular components. To weld the boxes (there is a nice picture of them in Char Leclerc: De la guerre froide aux conflits de demain) to the container walls or roof would be impractical; they are secured by means of bolts, clamps etc. To replace them one has merely to weld open the turret roof weld seams, which can be done in the field if necessary.--MWAK (talk) 18:46, 6 January 2011 (UTC)
* You say depleted Uranium (DU) is "rather soft" and it would be in special alloys which contain Titanium or Nickel as hard as armour steel. Then why would they use DU (even as perforated elements this would be any senseless, if DU would be only as hard as steel while having a much greater weight)? And your statement that the DU is used ater the ceramic matrix imho supports my opinion: DU and Tungsten aren't very effective on their own. If the DU "mesh" is located behind the ceramics, it might work as "backing plate".
* There are several sources claiming that the Leopard 2 uses a Chobham-like armour: the oldest one I found is from 1977. In this Christopher F. Foss (& co-authors) says that at first it was believed that the Leopard 2 used Schottpanzerung (as the first prototypes did), but then "at the end of 1976" it came out (or it was announced, this is troublesome to translate without being biased) that the in Britain developed Chobham armour/system would be used. Furthermore he gives one pretty simple description of Chobham: "This [Chobham armour] is several layers of steel and ceramic plates [tiles], which alternate each other." Then there is the scan/images of original British documents, which shows that the British already demonstrated "Chobham" (i.e. Burlington) armour to a West German comitee as early as 1970. Worth mentioning is also the fact that there was a Anglo-German joint project, the FMBT programme from 1972 to 1977. The article currently contains a sentence, which supports the useage of Chobham/Chobham-like armour in the Leo 2: Instead of rounded forms, the turrets of tanks using Chobham armour typically have a slab-sided appearance. The German wikipedia, itself citing several books, also claims that a Chobham-like armour is used.
* The Leclerc MBT is having modular (exchangeable) armour, the Challenger 1 & 2, the M1 Abrams and the Leopard 2 don't have modular base armour. Their armour is "built-in", changing the turret armour composition would require a new turret. [7] [8]
--Tim.vogt (talk) 14:49, 8 January 2011 (UTC)
The protection offered by a metal armour component is not only determined by its hardness but also, among other aspects, by its density or mass. Disregarding other advantages, a uranium perforated armour mesh a foot thick would thus provide the same protection as about 80 cm of steel. No weight gain compared to a steel perforated armour per definition — but a lot of space saved. So using this option would obviate the need for very major design changes when improving the protection level against KE-threats. Possible other advantages of heavy metals include increasing the density differentials which improves the chance of the penetrator being deformed or breaking. The backing of a ceramic tile matrix is a very specialised component, optimised to support and cushion the tile in such a way that the damage to the matrix by an impact is minimised. Making the ceramic directly touch the mesh would be far from ideal, to put it mildly. Of course you could put a plastic layer in between but that would still compromise the modularity. In this modularity there is no fundamental difference between the Leclerc and the M1 and Leopard 2. What was different was that the French chose to openly present it as an advantage. And the outer stowage box rim of the Leclerc turret was originally meant to hold an ERA-layer. The pictures you referred to are very illuminating: they show the basic turret as it is: a thin-walled empty container in which the modules can be placed (the Challenger 1, in essence still using the cast Chieftain turret, is a major exception in this respect). Obviously the factory revision is an ideal opportunity to check, maintain or replace the modules. But it can be done in the field also: the Americans in 1991 openly stated that the new uranium mesh modules were inserted by the troops deployed at the Iraqi border in Saudi-Arabia. One should not be deceived by simplistic diagrams of "special armour": they suggest it is a single block with all components tightly jammed in. This would however be hugely impractical and be a major obstacle to easy production, maintenance and replacement. The Soviet system was basically different from Western practice of course.
The 1976 incident is a delicate matter. We have to understand it was not a deliberate deception. The Chobham facilities brought forth two major developments: the one was the tile system, the other the use of foam. The Germans adopted the foam, using it in an improved form with a ceramic powder component in combination with armour laminates for the Leopard 1 A3 and A4. Later, when the demanded protection levels against KE-threats increased, this was further developed into a perforated steel armour system. When the Americans made the choice for a ceramic tile system, they began to exert considerable pressure on the Germans to adopt it. Late 1976 the Germans, against their better judgement, still cherished the hope that the Leopard 2 might be chosen as the common American-German tank, so they kept open the option of using ceramic tiles. At the same time they had begun changing their perforated steel system by replacing the foam in the cavities by alumina inserts, a version later rejected because the weight and cost penalty was not justified by the very marginal increase in protection against HEAT-threats. In 1976 the British and Americans disclosed the existence of "Chobham". This put the Germans in a awkward position: as they had earlier stated that their models were protected by spaced armour, this would now give the false impression that the Leopard 2 would be a generation behind and grossly inferior to the M1. Given the fact that at the time there was a real possibility it might indeed be equipped with it, they thus claimed that the Leopard 2 would be protected with Chobham-equivalent armour. This of course had the advantage of them not having to disclose their own perforated armour concept! Eventually the Leopard 2 would not use "Chobham". BTW, though a slab-sided turret is logical for a tank using ceramic tiles, the reverse isn't true: slab sides do not imply Chobham but modularity. The Leclerc is slab-sided too, though this is obscured by the bevelled stowage boxes.--MWAK (talk) 09:22, 9 January 2011 (UTC)

Chobham armour[edit]

I have a really hard time believing the describtion of Chobham armour function's against hollow shaped charge weapons. I don't really see how "Hardness", "cracking" or "ragged entrance channel" has much to do with stopping a jet of very hot molten metal. Not being a expert in materials, I would presume that any material coming into contact with such a hot jet and thus subjected to extreame temperatures and pressures, will simply melt or even vaporise (mostly as grains). (And thus it loosses it's structual brittleness and hardness, though the individual grains keeps the hardness). My - lay man's - Understanding of Chobham, armour is that it works like reactive armour: You have a sandwich structure of two plates with a ceramic in between. When the outer plate is hit and penetration begins, energi is transfered through the outer plate and to the ceramic in form of high pressure. Because the ceramic is confined (by the outer and inner plate) the pressure result in a steep temperature increase which more or less vaporises the ceramic, creating a gas under high pressure consisting of grains of the ceramic. When the molten jet, of the shaped charge, burns through the outer plate it so to speak "punctures the baloon", and the high pressurised gas (of the ceramic material) shoots out, directly against the direction of the molten jet. This causes the molten jet to loose momentum and de-focusses the jet. This also explains why chobaham is more effective against HEAT than Ke penetrators, since while the reactive effect does, I presume, significantly decrease the momentum of the penetrating rod (f.ex. by abrading it, I suspect) it can't "de-focuss" it or, more relevant, make it change direction (because the reaction "jet" and the rod moved in more or less exact opposite directions).

I suspect that if you want to use hardness (to shatter the penetrator) or cracking (to divert energy laterally) you would want to have the penetrator make a clean hit on that material, not allow the penetrator to "prime" that material by heating (which makes the material more soft and less brittle) as it strikes through outer layers on it's way through the entire armour package. Jomsviking (talk) 11:49, 3 January 2011 (UTC)

Well, you have become the victim of simplified accounts in popular books about the functioning of hollow charge weapons. Contrary to what is commonly stated there, the explosion by a hollow charge does not form a "jet of molten metal". Yes, there is a jet, but of hot gasses. And there is metal but not in a real jet nor is it molten. The explosion force compresses the soft metal covering ("liner") of the hollow cone and deforms it. This happens so quickly that it simply hasn't got the time to melt. Instead a "hypertensile" stretched metal string is formed. The penetrative qualities of this object largely depend on its speed and mass, not on its temperature. Basically it is just a KE-penetrator but with a very high speed (the tip would leave the planet if not for the atmosphere), a rather low mass and very little cohesion because it is in an immediate process of disintegration. The latter is its Achilles heel, exploited by ceramic armour. And no, also the gasses do not sufficiently vaporise the ceramic for a "balloon" to be formed — although they contribute to the velocity of ceramic particles that break the "jet" geometry. These particles are not the "grains" of a gas: a gas has per definition no grains and if the gas pressure would be directly effective it would not matter much whether it had been made from metallic or other molecules and ceramic armour would offer no advantages over steel. However, the main mechanism is simply that the penetrator follows the path of least resistance, being the rather chaotic cracks in the ceramic.--MWAK (talk) 20:36, 3 January 2011 (UTC)
You have to cut me some slack in the prober use of technical terms in english, what little material physic I was thought a long time ago was in a different lanquage.
I accept your better describtion of a shaped charge. Though as far as I can see it doesn't really make a difference in respect to what I am trying to say.
I apologize for the confusion created by me using the word "gas", maybe a "dust cloud made up of tiny grains/pieces of the ceramic" would have been better?
"However, the main mechanism is simply that the penetrator follows the path of least resistance"
That's a new mechanical principle for me; So we have a jet of hot gasses; plz explain how these molecules/particles change their momentum to magically follow the path of least resistance? (the "jet" would probably propagate longest along the path of least resistance, but that doesn't mean that it follows the path of least resistance)
"it would not matter much whether it had been made from metallic of other molecules and ceramic armour would offer no advantages over steel."
Let's take the "dust cloud" picture instead of a "gas", the difference would f.ex be the hardness of the grains/tiny pieces of the ceramic and the high melting point (preventing the transition into a proper gas). But ofcourse if chobham armour doesn't work this way, it's irrelevant. Though you do write; "although they contribute to the velocity of ceramic particles that break the "jet" geometry."
You mean that particles are moving freely? If particles are moving freely, one would suspect that the moment the "jet" get into contact with such a medium of moving particles, it will be bombarded by them (because of the high velocities involved, because temperature is high), which as you say "break the "jet" geometry.", or as I like to put it; defocuss it and results in the "jet" dissipating in a larger volume of material - and thus loosing it's penetrating power.
Which is exactly what I stated in my opening post;
" I don't really see how "Hardness", "cracking" or "ragged entrance channel" has much to do with stopping a jet of very hot molten metal." (where "hot molten", should have been "hot gaseous" or something)Jomsviking (talk) 22:46, 3 January 2011 (UTC)
I fear I've been not sufficiently clear. Yes, we do have a jet of hot gasses but this real jet is of minor importance. Let's forget about them for a moment and concentrate on the main mechanism. The penetration is largely effected by the "sting" of hypertensile metal. This sting is not gaseous nor a fluid but a solid in a process of extreme deformation. When its tip impacts the tile surface it will cause the ceramic to crack at that point. This is why hardness and brittleness are essential: a too soft or too tough material will not crack. The cracks will not nicely follow the ballistic trajectory of the sting but form at an oblique angle. This means the tip of the sting will now encounter an oblique surface and will be deflected in the direction of the crack, hit more ceramic nevertheless causing more cracks, etc., etc. until it is defeated. At first the incoming broader parts of the sting will be forceful enough to create a more or less straight entrance channel anyway but its ragged sides will nevertheless keep obstructing and deflecting the subsequent even broader parts of the sting, a process enhanced by (preferably large, not small) pieces of the ceramic of the channel wall breaking off. So that is also part of the defocusing. The later, much slower, sting parts will not find a nice small entrance hole at the end, formed by the tip, as when steel armour is hit. Instead they will encounter a heap of ceramic rubble. When the tile is thick enough during the last phase the remaining metal, the back of the "carrot", will "mushroom" sideways. So, a lot of culinary similes there: I hope the explanation is edible ;o).--MWAK (talk) 08:54, 4 January 2011 (UTC)
I think you have desribed to me some basics about how ceramic armour diverts energy and momentum laterally. And I think it sounds reasonable. Though I find it hard to believe that the famed Chobham armour, that revolutionized (then) modern tank warfare, a great secret of the western world and one of "our" then best cards in offsetting the numerical superiority of the warsaw pact armoured forces, was "simply" a question of producing and manufacturing a ceramic like Titanium diboride (or other ceramics like that) in a tile (matrix of some material, what ever) and utilizing it's (inherrent) material properties. I would suspect that the "communists" would have caught up to that idea pretty fast. I suspect that (or reason dictates) that there has be something subtible, something that aren't or weren't more or less common (for specialists) ceramic knowledge at the time - but ofcourse that's a secondary argument. Jomsviking (talk) 11:25, 4 January 2011 (UTC)
also, but that's just pure speculation from my part, I am puzzeled why a high momentum impact in a very short time, simply doesn't shatter the ceramic (which as far as I know is quite stiff) into a fine powder (kinda like hitting burnt clay with a hammer), in which case the crystaline/structual properties (lack the correct word) you describe is irrelevant Jomsviking (talk) 11:39, 4 January 2011 (UTC).
Well, the reason why this technological development eventually was advantageous to the West was precisely that the Soviets had a head start. Being the first to implement a cheap version, induced them to start mass production of too light types, in the 40 ton class. But you need a 55 ton vehicle to really benefit from these systems. I have no doubt that if the tile system was not invented by them in the first place (you never know), it was certainly known to them shortly after its conception. So, it was not The Great Secret nor strictly necessary to offset the numerical disparity which was not all that extreme to begin with. I strongly suspect that the mystique surrounding Chobham stemmed from people despairing of explaining terms like "hypertensile" ;o).
Regarding "shattering" versus "cracking": the difference is gradual. But the comparison with a hammer is very informative. I knew a ATGW-instructor once who tried to boost the morale of his TOW-teams by showing them that ceramic armour was far from invincible. He had a whole supply of old alumina tiles from the Americans and at the beginning of the lesson he showed one to his audience, explaining it was an advanced ultra-secret material providing superior protection. Then he lifted a normal hammer to hit it with. The men of course expected it would simply bounce off without even a scratch being made. Every time they gasped with surprise when he easily shattered the outside and whole chunks flew off. Ceramics are vulnerable to rather slow impacts with heavy masses. The hollow charge "sting" is to the contrary very fast and very light. "Momentum" has two component factors; its all depends which is the dominant one, speed or mass.--MWAK (talk) 17:13, 4 January 2011 (UTC)
""Momentum" has two component factors; its all depends which is the dominant one, speed or mass."
Exactly; you have lowish mass, but very high velocity, which translates into a high momentum. The derivative (rate of change) of the momentum with respect to time is the force (or the momentum is the integral of the force wrt time), hence if the change in momentum is large wrt time, then the exerted force will be large. In this case we have a high speed "collision" that is over in a very short time, hence the rate of change of the momentum (the derivative wrt time) is huge and the force exerted (or rather the force necessary to bring about the (rapid) change in momentum in the given timespan) will be huge, this force is the (oppossed) force that will be used deform the material. But when "enough is enough": at which force a significant part of the ceramic is shattered into powder, I don't know Jomsviking (talk) 20:06, 4 January 2011 (UTC).
Indeed, the kinetic energy depends on the time period and thus can be expressed as ½mv². So, in principle the penetration increases with the square of the velocity. Obviously, there is a modicum of pulverisation at the impact point, but that point is very narrow limiting the amount pulverised. So the front of the sting which is best suited to cause a deep penetration because of its very high speed and high concentration, is the part confronted with the highest relative cracking. The parts arriving later relatively pulverise more material while widening the entrance channel but are slower and broader and thus would have contributed less to the penetration anyway.--MWAK (talk) 07:22, 6 January 2011 (UTC)
Just some physics; The energy is less interesting in the describtion of the collision. The see that, imagine two car accidents; Identical cars speeds at 100Km/h against a concrete wall. The first car hits the wall at 100km/h while the second car breaks down to 50 km/h before it hits the wall. Both cars are brought to a complete stand still in the collision. Now the driver in the first car is toast, but the driver in the secondcar, given seat belt and modern car, will get away from this with minior injuries. Now the "before and after" momentum and the "before and after" energy are the same in the two situations, and the work done on each car is the same. But the force excerted is not the same in the two situations. The guy and car that hit's the wall with 100 km/h is beaten into a pulp by a huge force, while the other guy experiences a much more moderate force (though, in a longer time). It's the force that "breaks" things, (very)coarsely speaking it's the mass times the time interval times the (de)acceleration that causes the damage. In our ceramic it will be the force of the impact that shatters the ceramic first of all, along it's grain boundaries. The force is related to impuls/momentum by the integral of force (it's much harder to derive the force from the energy) Jomsviking (talk) 09:28, 7 January 2011 (UTC).
Anyway, I lack the knowledge, though I am very surprised that "cracking" can make such a difference, since I would believe that the principle manner of penetration is by the "sting" pulverising the ceramic as it goes along (and hence there is nothing to "crack") Jomsviking (talk) 09:28, 7 January 2011 (UTC).
If the warhead is powerful enough and penetration succeeds, that is what will happen of course :o). To understand the defeat mechanism better one should also consider another factor: dwell. The metal of the sting point is slowed when it impacts the tile face. But the shock waves this causes are not and crack the ceramic well in front of it and also in a more lateral direction.--MWAK (talk) 09:26, 8 January 2011 (UTC)

Development and application section[edit]

What a bunch of nonsense, the development of the Leopard 2 armour has no place in the article. It is almost as though whoever wrote it was trying to make some sort of apology/comparison and why on earth is there any mention of GIAT? Twobells (talk) 15:14, 29 June 2012 (UTC)

Well, I can refer to the second line of the intro: "The name has since become the common generic term for ceramic vehicle armour". So, very strictly limiting the scope of the article to the British research and its direct American offshoots is unwarranted. Therefore it is relevant to indeed make a comparison with the systems of other nations, including one from GIAT.--MWAK (talk) 05:54, 30 June 2012 (UTC)

precise and formal[edit]

In what way is this wrong?- Chobham armour is the composite armour developed in the 1960s ...

All wikipedia needs is that "Chobham armour" is the wp:commonname. To say- is the name informally given to, is wrong unless there is another common name. If there is another name we should use that instead. Bhny (talk) 12:22, 7 May 2013 (UTC)

The "informally" simply informs the reader that it is not an official type designation. It is important to stress this to avoid ambiguity. It is not a matter of stating the obvious as the "common name" might well have coincided with the official one. Also there is the problem that the name might be used in a limited sense, only referring to the British project, or in a more general sense for any type of ceramic armour. This makes it even more desirable to be clear from the onset about its informal nature. Past experience has taught me that all kinds of confusion will result otherwise :o).--MWAK (talk) 06:02, 8 May 2013 (UTC)
what is the official name? Bhny (talk) 13:25, 8 May 2013 (UTC)
Good question :o). The generic concept of course does not have a single official counterpart. The British armour seems to have been known as "Burlington" but even that is not a formal factory designation.--MWAK (talk) 18:39, 8 May 2013 (UTC)
Although only a guess, I suspect that at some time it may have had one of these; List of Rainbow Codes — Preceding unsigned comment added by 80.7.147.13 (talk) 19:23, 24 January 2014 (UTC)

https://en.wikipedia.org/wiki/Heavy_water[edit]

I have watched some military television content and I noticed that a greater explosive reactive force could be achieved when water seperated the explosive detonation and the target.

I notice there is something called Heavy Water on wikipedia

Would an inclusion of heavy water in your reactive armour provide a greater counteracting force?

I think all this knowledge is in the dambusters project.

Best Regards

Darren Mark Horton

82.29.73.4 (talk) 15:51, 2 April 2017 (UTC)

Well, it depends against what kind of explosion you want to protect. Normally, any protective belt defending against a single explosion is ideally very tough and at the same time very inelastic. Like some ceramics really. Water in general is not ideal. Heavy water is somewhat better but unless you are designing an interplanetary spacecraft and need water as a belt to protect against cosmic radiation anyway, I wouldn't bother. And you can't use heavy water as a normal consumption supply because in the end it wrecks your cell chemistry. You'll get sterile and ultimately you die.
For protection against hollow charge explosions, water is pretty good but not good enough to be practical for use on vehicles.
But perhaps this is not what you are really asking. If e.g. a depth charge would explode in a heavy water ocean, would this lead to greater or lesser damage to a submarine? I'm not quite sure but I presume the expansion and contraction cycle would be intensified, leading to greater damage.--MWAK (talk) 16:59, 2 April 2017 (UTC)