LULZ

hello, i very much like WarThunder for confirming Challenger 1 is indeed, a steaming pile of shit 
 

I don't think there is a possible explanation, because people are beginning the argument from the wrong direction. People are making assumptions about the protection level, then try to find sources supporting it - i.e. first comes the thesis, then sources are searched to support it. That's the wrong way to start research - saying "the Challenger 1 needs to have 500 mm RHAe against KE" and then gathering all sources that say somewhat related. I can understand that Laviduce expects a high level of protection based on the thickness of the Chieftain's Stillbrew armor package and based on the greater weight of the Challenger 1 MBT - it could have a protection level of 500 mm vs KE. But we have no confirmation to these theories. With British documents showing that the estimated penetration of 125 mm tungsten-cored APFSDS ammunition was only 475 mm at point blank, I have serious doubts that a protection level of 500 mm or more against APFSDS  was required - that's simply not how tanks are designed.
 
The Challenger 1 development was pursued at a different timeframe than the Chieftain upgrade with Stillbrew armor, thus the requirements were different; in so far "just" 400-450 mm vs KE might be a lot more realistic based on the requirements for the MBT-80 project and the data of the Shir 2, assuming the armor package was improved over the latter tank. The Challenger 1 was approved in 1980, the Stillbrew upgrade in 1984. A lot can happen in four years of the Cold War. Even the Chieftain with Stillbrew doesn't reach protection comparable to 500 mm rolled armor steel vs APFSDS ammo, because cast steel provides up to 20% less protection than rolled armor steel.
 
Ceramic armor is not a magical solution to all problems. The T-64A used ceramic armor, yet it protection level was rather limited compared to later tanks.
 
 
This is wrong. The cited book - at least in its original German version - does not say what is claimed in the first paragraph of this screenshot of "Armor Basics". While the first quote can be found pretty much verbatim on page 76, the second part - i.e. "the ballistic effectiveness of the compouned armors against KE penetrators shows an improvement of only 1.2 to 1.4 over homogeneous rolled steel plate (incontrast to a factor of  2 against shaped charges." - cannot be found on page 76 or 77 of the original book. I have never read the translated version, but I am fairly certain that it doesn't say what is claimed previously.
 
On page 75, the claimed efficiency values (1.2 to 1.4 vs KE, 2 vs shaped charge) can be found: but that is in a paragraph on the armor protection of the T-72! The "factor 2 against shaped charges" is meant to be the mass-efficiency value and is based on a Swiss assessement from a 1982 issue of the Allgemeine Schweizerische Militärzeitschrift claiming that the T-72's hull armor is weight equivalent to a 120 mm steel plate sloped at 70° and provides twice as much protection against shaped charge ammunition as steel armor of the same weight. The same article also includes statements about the supposed performance of the T-72's armor against KE ammo: the article claims that the T-72, M1 Abrams and Leopard 2 use special armor and certain types of special reach a efficiency against KE ammunition of 1.2 to 1.4 per thickness (!). The T-72, which was believed by the Swiss authors to feature a 300 mm line-of-sight thick array of such armor (in reality it had a simple cast steel turret with a thickness of up to 500 mm, while the hull armor has an effective thickness of 547 mm), would then reach a protection level of 360 to 420 mm.
 

 
We know for fact that the T-72's armor neither reaches a mass efficiency of 2 against shaped charges nor that it provides a thickness efficiency of 1.2 to 1.4 agianst kinetic energy ammunition. It is a false assumption based on incorrect data from a time when the T-72 was still a mystery to NATO and non-aligned countries.
 
Everything else - regarding the effectiveness of ceramic armor - is not related to the Challenger 1. It is pure, unreferenced speculation that the tank would be fitted with such armor, even though it has been proven that Chobham is (mostly) based on spaced NERA sandwiches. Based on a number of declassified documents on the development of Chobham armor, there apparently were more than a dozen different Chobham armor arrays being tested in the early 1970s. Some of them were merely improved versions of earlier designs, others were created to experiment with new concepts (e.g. there was on Chobham armor array that incorporated high explosives similiar to integrated ERA). There might have been some Chobham arrays with ceramic component in them and this development might have lead to the array adopted on the Challenger 1  - but there is no proof for this; even if they are included, ceramics would only play a minor role. CeramTec ETEC, one of the market leaders in Europe for manufacturing ballistic ceramic materials, includes photographs of the Leopard 2 in its flyers, suggesting that some ceramic elements might be part of the armor array.
 
However suggesting that the Shir 2's 325 mm steel-equivalent protection against APFSDS rounds could be increased to 500+ mm just by incorporating ceramic materials seems wrong. Burlington and Chobham are different names for the same thing - there are numerous files using both names to refer to the same armor arrays. According to the British DSTL, modern armor arrays designed to provide protection against KE and HEAT rounds follow a three-stage layout, i.e. they consist of:
a distrupting stage to break KE pentrators and shaped chage jets a distrubing stage, which makes sure that the particles and fragments of the broken penetrator change direction and yaw angle an absorbing stage, which stops the fragments from reaching the interior and absorbs the kinetic energy The options for designing the second stage are pretty much limited to different types of spaced multi-layer armor or other types of reactive armor; based on known armor arrays - such as the T-72B's armor and the M1 Abrams' armor, the distrubing stage usually takes up at least half the available armor volume. The first stage is often based on a reactive armor (see the wedge-shaped armor of the Leopard 2A5 or the Kontakt-5 ERA on late Soviet MBTs), although it could also be made using high-hardness steel, perforated armor or ceramic plates (the latter two variants being common on lighter vehicles, because this armor is more efficient against short, bullet-shaped penetrators). The absorbing stage also can include ceramic materials, but will always include a steel layer (which serves as strucutral support) and potentially kevlar, polymers or other materials.
 
In case of the M1 Abrams, the absorbing stage of the hull armor was a rather simple steel plate.
 

 
So simply adding ceramics to the armor won't drastically change the protection. The Challenger 1 would require a completely different armor array, which would suffer from the typical problems of ceramic armor against large calibre ammunition, such as a relatively low efficiency, low multi-hit capabilty and problems with cost and manufacturing. Armor consisting of layered aluminium oxide with polymer backing and steel enclosure provides the same protection against shaped charges as steel of the same thickness - thus a Challenger 1 with 700-800 mm frontal armor at most would be quite vulnerable to shaped charges.
 
 
The "Armor Basics" document from which these snipplets are taken is known to be outdated and incorrect in various aspects. The author speculated too much and used false premises to generate his values - armor thickness, armor weight and layout are often wrong. Here for example he ignored that the Challenger 1 turret is meant to provide protection along a 60° frontal arc (30° to each side of the turret centerline), but the Chieftain was designed with protection along a 45° arc only! Thus his whole idea of using the weight difference to scale the equivalent armor weight of the frontal armor is incorrect. He also claims that a 15% increase in steel mass would result in a steel mass equivalent to a thickness of 50 cm - this would mean that in his beliefs the Chieftain was having an armor thickness of 434 mm, which it does not have in reality - the thickness of the frontal turret armor of a Chieftain is about 240-280 mm according to sources posted earlier in this topic.
 
 
I don't know any "Ed Francis" and see no reason why his writing should be relevant to this discussion. Seeing that the origin of this quote is a post on the Warthunder forum, which wasn't even written by him, but somebody claiming to have spoken to him, I would be rather careful. This is a big pile of unreferenced claims, that in some cases is rather easy to disprove. It is all speculation with no sources.
 
If Burlington and Chobham were two different things, why would official US and UK documents use both names like synonyms?
 

 
There are dozens of documents on the development of Chobham/Burlington armor, which are using both names; they also use "Chobham spaced armour" and similar terms disproving the claims that supposedly were made by Ed Francis. And this is how the Chobham spaced armor is shown in the same document - no trace of ceramics!

 
Ceramics themselves do not bulge, but rather break; the elasitic backing behind the ceramic tiles will bulge. Ceramics are not suited for NERA sandwiches as long as multi-hit capability matters,
 
Even if this forum poster had asked Ed Francis on the topic and he let him type on the Warthunder forum with his account, I don't see why this name would result in the text being relevant to us. According to a quick google search Mr. Francis is a volunteer at Bovington, not an expert on AFV design and armor technology. Given that there seems to be no special credentials to his name and that Bovington still has a plaque citing incorrect armor values in front of the Chieftain tank, I do not consider this to be a source.
 
 
There are no exact figures, which is also related to the problem of "irrecoverably lost" being a philosophical question. However the Abrams supposedly did perform very well in ODS. There were 14 Abrams tanks with DU contamination after being struck by DU rounds or on-board fire, for which the US Army lacked procedures and equipment to deal with. If they recovered these later or not is unknown to me.

hello, i very much like WarThunder for confirming Challenger 1 is indeed, a steaming pile of shit