Talk:Sloped armour

message: ::Nice picture Graeme!--MWAK 07:08, 28 June 2006 (UTC)
replies: text: It came about it while playing with my son's wooden bricks - take two triangular ones slide them past each other and voila! GraemeLeggett 08:44, 28 June 2006 (UTC)
thread_title:  Picture 

message: The explanation of physics in the article is extremely poor. "LOS" is not a term used anywhere, by any engineering or scientific discipline, and it is flawed by definition because ballistic projectiles always travel in an arc. It has been made up, and is both misleading and ignorant.
In the formula "vertical" is also rubbish - this should be a normal to the vector of incidence. To simplify this: theta should be a combination of: 1) the armour angle from vertical, 2) angle of the vehicle itself 3) and also adjust for the angle of the incoming projectile.
Because convention is to express sloped armour angles in degrees from horizontal, it would be better to use sine() rather than cosine() in the formula. Preceding unsigned comment added by 85.134.180.68 (talk) 13:23, 25 April 2009 (UTC)
replies: text: Well, the physics used in the article is of course extremely basic. Very simplified cases are treated to explain the essentials to the reader. Allow me to address some of your concerns:
#"LOS" (Line-of-Sight) is indeed not a physical term. However, it has not been made up — at least not by us :o) — but, perhaps worse, is military jargon (used e.g. here: http://www.forum.sudden-strike.ru/attachment.php?attachmentid=6811 ). Remember that most military personnel have never received a very thorough education in physics. That the angle of incidence changes as a function of distance, that the positive effect of sloping is in some measure negated by this and that there is also the complicating factor of precession, are most important aspects, that definitely should be elaborated by someone (you perhaps?) but the normal educational procedure in this case is to first pretend that the projectile strikes travelling along the horizontal plane and that the vehicle is in a "neutral" horizontal position. A select few can then be introduced to higher truth. To see that the normal human mind already has to strain itself to grasp the implications of the first step, it suffices to read this talk page.
#Given that the projectile moves along the LOS and the vehicle is in a "neutral" position, the formula is, to the best of my knowledge, correct. Obviously sections treating more general cases have to apply different formulae. You have correctly pointed out that the text fails in making the position assumption explicit. I'll remedy this immediately.
#The military convention is to give the angle from the vertical. The military see vertical side armour as the standard situation, the aberration from which should be indicated. Accordingly the formula applied uses the cosine rule, and is referred to under that name in standard military jargon.--MWAK (talk) 19:21, 25 April 2009 (UTC)

text: Well, the term LOS did not originate in this forum. My point was that military terminology differs from that used by physics. Your claim "If you want to have the same internal space with sloped armour you have obviously to expand the tank dimensions" is problematic. In general, sloping allows a better approximation of the ideal form to envelop a given volume with a minimal surface: a sphere. Best-fitting the armour to some ideal ergonomic configuration might indeed result in a lower volume but with a certain weight penalty due to a larger surface. During the Second World War, major impediments to applying sloped armour were a limited capacity to produce large cast sections and a limited capacity to manufacture large thick plates. Often, not much thought was given to it and the armour was simply "wrapped" around a normal configuration. The Merkava is an interesting case. The Merkava I apparently did not use composite armour and the extreme angling was intended to defeat long rod penetrators which, due to the back plate effect, would have more easily overcome a less extreme slope than a vertical plate.--MWAK (talk) 09:44, 17 February 2020 (UTC)

text: I can assure you that the term LOS far predates the invention of computer games. As indeed, I do myself, perhaps the reason I don't have game buddies :o). Your point about sloping in principle having to be balanced against the demands of ergonomics and transport is of course a valid one. Could you provide some actual instances of WWII designs in which sloping was deliberately avoided for this reason? Obviously, some amphibious tanks were made bulky on purpose.--MWAK (talk) 11:48, 20 February 2020 (UTC)
thread_title: Extremely Poor Physics

message: Basically it seems to me that the horizontal armour has been ignored,
unless it is open space, which is not so good for armour.
Taking a 45deg slope versus straight, and say a 30cm length/height with 10cm of armour.
Right angled armour @ 10cm Area would be 30x10+(30-10)x10=300+200=500 sq cm
Sloped armour at 45deg would be 42.4x10 = 424 sq cm
Obviously the right angled horizontal could be reduced (which is generally done for non sloped).  — Preceding unsigned comment added by 95.172.68.145 (talk) 12:45, 8 August 2013 (UTC)
replies: text: Well, to simplify matters the limiting case has been explained in which an attack from a single "direction" has to be defeated. Indeed this could be expanded to a model with attack from all possible directions — but then sloping becomes irrelevant for deflection and trivial as regards the weight-volume ratio: the ideal form would then be simply a sphere! More complex models can be made in which a certain probability is assigned to a certain direction. And it is possible to create the model describing the total of all such models. However, the mathematics would be quite complicated.--MWAK (talk) 18:37, 8 August 2013 (UTC)
thread_title:  Hasn't the horizontal armour effect been ignored 

message: User:Irondome Hello, I noticed that you reverted my edit of adding the Mareșal tank destroyer. May I know why? Is it anything of what I said not true? The Mareșal came before the sloped German TDs, it's a fact, nothing untrue about that. I never even stated that the Hetzer was based on it, which is something debatable, I just stated the fact that Mareșal came ahead of them, which is 100% true. What's the matter, can't risk ripping away any of T-34's glory? Are only the "Great" ones allowed in the article, is this article racist by any chance? Do you have something against the Mareșal? Awaiting your reply. 79.113.130.48 (talk) 03:52, 13 April 2016 (UTC)
replies: text: Well, the Mareșal is not a very important example of sloping because its designers were hardly original in applying the principle and the type never became operational. It is outside the scope of the article to give a list of all vehicles with sloping armour. I have to admit the design is a very extreme case, the Mareșal looking like a tracked pyramid :o).--MWAK (talk) 05:44, 13 April 2016 (UTC)
replies: text: 79.113.130.48 (talk) Firstly I would be careful of casually throwing around accusations of "racist", or "having something against" something which is basically a piece of metal. I fully endorse MWAK (talk)'s points. Really the article is no place for a detailed list of specific types. I would suggest you further expand and improve the Mareșal article itself, bringing further sources to bear. Also I suggest you look at Leonardo's fighting vehicle. The concept of sloped armour is hardly new.. Irondome (talk) 15:23, 13 April 2016 (UTC)
replies: text: Is that you, RoumanianandProud? Irondome (talk) 13:39, 14 April 2016 (UTC)
thread_title:  Mareșal tank destroyer 

message: In the section about deflection: "If the projectile travels very fast, and thus is in a state of hypervelocity, the strength of the armour material becomes negligible – as by the impact both projectile and armour will melt and behave like fluids – and only its area density is an important factor."
Early research into hypervelocity domain physics (by Held, et al) treated interacting solids as liquid because this was the best model they had at the time for predicting interaction behavior, but in fact the materials do not melt and remain solid.  More recent models -- most notably the excellent Lanz/Odermatt formula -- incorporate the strength of the penetrator and penetrated material as parameters.  It is more correct to say that the strength of the armor is less significant than it is in the ballistic velocity domain.
I've had rotten luck editing armor pages in the past, as my edits almost always get reverted despite including references.  I'd be willing to make a stab at untangling this, though.  TTK (talk) 17:08, 23 July 2018 (UTC)
replies: text: Well, at the time I inserted that explanation to make things a bit more understandable for the layman. I agree that the text is simplistic at this point. Would "as on impact both projectile and armour will behave more or less like fluids" be an improvement? In any case, we must keep in mind that any information must be relevant for the subject: deflection. And yes: the Lanz-Odermatt formula, though still a very simplified model, accounts for tensile strength but, as the authors state: "The formula simplifies to pure hydrodynamic penetration in the limits of large impact velocities and normal incidence"!--MWAK (talk) 20:24, 23 July 2018 (UTC)
replies: text: That's fair, and I apologize if my assessment was harsh.  Yes, "as on impact both projectile and armour will behave more or less like fluids" would be accurate and an improvement.  Regarding the formula's behavior at its limits, it's true, but "large impact velocities" are very, very large.  The penetration behavior of HEAT penetrators is still somewhat dependent on material strength, and those are five to nine times faster than hypervelocity long-rod penetrators.  I only bring that up because the behavior of long-rod penetrators is very interesting, close to the ballistic domain, and that contributes to some weird and sometimes counterintuitive or contradictory behavior with regard to sloped armor, sometimes turning into it, sometimes turning away from it.  This wikipedia article touches on some of them, but if you think it wouldn't detract from it, I'd like to take a crack at distinguishing between ballistic behaviors and hypervelocity behaviors, and which effects can contribute to the sloped armor offering a higher mass efficiency than vertical armor of equivalent LOS thickness. TTK (talk) 07:25, 24 July 2018 (UTC)
replies: text: I have every confidence that your contributions will be valuable! Do not hesitate to add sources as the article sorely needs them.--MWAK (talk) 14:28, 24 July 2018 (UTC)
replies: text: Yes,TTK (talk , I too have confidence that your technical knowledge will improve the article. I have been following this, and particularly the form of words needed in the sentence discussed above, has been plaguing me! Irondome (talk) 14:42, 24 July 2018 (UTC)
replies: text: Thanks for the encouragement :-) I haven't forgotten about this, but decided fleshing out the page on Hypervelocity a little is a necessary prerequisite for improving this one.  I hope to add content there next week. TTK (talk) 04:03, 29 July 2018 (UTC)
thread_title: Misconceptions about hypervelocity domain behavior