Where does this 500mm number come from? Is it
the tatget frontal protection level for Arjun?
No, genious, it ain't. It's just the hotshot IItians at the CVRDE just forgot to extend the armor cavity further back into the crew compartment behind the GMS while copying the Leo2A4 turret, which leaves about ~400-450 mm of space for armor, which means there's simply no room left in there to put any composite inserts and retain the level of protection necessary for a critical position like that.
Here is a photograph of an underproduction Leopard 2A4 in the factory
The cavity in red is where the GMS goes into, and the one behind in green is where they place the composite armor materials. Note, how the armor in the right extends further back as compared to in the left. This ain't the case for Arjun, sadly.
And as for the mantlet, we've seen it with the faceplate removed, and there was no composite armor there. And even 500mm is being way too generous I would say, given the design. Do keep in mind that you have to leave room for the gun's servo mechanism inside the mantlet and that makes the room available for armor in there quite limited (unless you can come up with a different design like the South Koreans did, which isn't the case for Arjun).
Also, your general statement that composite armor is always less effective than the same thickness of RHA is questionable.
For fuck's sake, go read a few books on armor development before clapping your traps, will ya??!!
With materials like ceramics and carbides that are all much harder than steel I find this hard to believe.
Just because your scientifically illiterate mind can not wrap itself around a certain fact doesn't make it untrue, simpleton!!
It is a well-known fact that steel is more thickness efficient but weight inefficient whereas composites are the exact opposites. Just do a comparison between the thickness of an AR500 NIJ Level III steel armor insert vs a Leve lII ESAPI one and see for yourself which one's thicker. The same applies to tank/AFV armor as well.
Steel is somehow the exact ideal material for defeating kinetic penetrators
Not ideal, just better cm for cm. What I mean by that is an RHA/HHA plate of a certain thickness will always provide a substantially higher level of protection against KE rounds as compared to a composite block of identical thickness.
When it comes to stopping heavy alloy penetrators, it's the relative density of the rod and armor material that counts much more than sheer hardness. And that's why we aren't even sure whether ceramics are at all used in composite armor in any meaningful amount.
and no other composite is more effective on a per thickness basis?
Pretty cool, isn't it??
If this is such a well established fact, it should be easy for you to find a source for it.
It's your job to find and familiarize yourself with the relevant facts before you decide to engage someone in a debate, on a subject you lack in any meaningful knowledge (made quite apparent by your ignorance).
