I want to calculate the weight required to make an armor that can resist 7.62 RUAG SWISS AP, also known as VPAM level 12. I needed a baseline so I took NIJ Level IV and then tried to find the difference of weight so I could get a percentage. The only plate that's still made for this threat is the TenCate CX-950 IC. This plate is 8.93 lbs for a sapi medium and is alumina in-conjonction with soft armor. I then needed to find a Level IV alumina IC, which I found on UARM's website. It's 7.6 lbs, so if we do 8.93/7.6 we get around 1.175, but I put 1.25 considering UARM's plates are often quite heavy. Now that we have 1.25, we can start applying it to silicon carbide and boron carbide. Denmark's group has a level IV silicon carbide plate at 5.95 lbs, so times 1.25 it gives 7.4375. Hesco's boron carbide IV plate is 5.1 lbs, so times 1.25 we get 6.375.
Now, I wanted to know what was the weight for hardened steel. I took MARS 600, which is one of the best armor steel you can get. Using this page, I can easily calculate that you would need about 19mm to stop it. Using a calculator, we know that a full inch sapi medium plate would weight 33.9 lbs. 19mm/25.4mm = 0.748 inch so if we do 0.748*33.9 we get 25.3572 lbs.
The problem is obvious : How is boron carbide 4 times as light as steel? Silicon carbide is 3.4 times as light too? It doesn't make any sense, giving that they are both around 2.2 ME and hardened steel is 1.3 ME, so it should be around 1.7 times heavier for steel. What did I get wrong?
I recently read about upgrade packages to old tanks like the M-60 and T-55, but kept seeing comments from people saying they would still be obsolete. Is this because the M-60 and T-55 are made entirely of steel (and not composite) armor?
I have this theory that thick steel armor is probably totally obsolete, and is just dead weight in the age of lighter weight composite armor. You can bolt on upgrades to an M-60 or T-55, but you're still hamstrung by the fact that either tank will be carrying around tons of useless steel. Am I right?
Also, if we wanted to upgrade old tanks like that, wouldn't the best idea be to develop a new turret--with lighter, modern composite armor and better technology inside--and just drop it into the old tanks? The hulls would still be made of heavy steel, but that could be helped a bit by adding applique armor.
Here are some of the upgrades I read about: