Modern composite tank armor is extremely effective. An M1A2 Abrams has an equivalent thickness of 3 or 4 feet of good steel. This for actual armor only a few centimeters thick.

The only real problem with it is "multiple hit capability". That is to say if the armor is hit in precisely the same place multiple times it becomes much less effective.

I propose a module containing a small stack of armor plates and a robot arm. The plates would have an air activated glue. In any lull in combat the robot arm could unseat itself and slap plates over any damaged armor prolonging combat effectiveness.
-- Voice, Nov 29 2012

M1 Abrams tank http://en.wikipedia.org/wiki/M1_Abrams
Please see armor section. [Voice, Nov 30 2012]

RHA http://en.wikipedia...d_Homogeneous_Armor
Rolled homogeneous armor [Voice, Nov 30 2012]

Actually, 1cm of Chobham armor is roughly equivalent to 3.5cm of cast steel when struck by a HEAT penetrator, so the supposed 10cm frontal armor (the specific thickness is classified, of course) on the Abrams is only worth about a foot of steel, not 3 or 4.

BTW, what is your definition of 'good steel'? Specificity will aid ensuant discourse.

A heat-activated glue combined with a small blowtorch on the arm would adhere much faster than an air-drying glue. Also, an arm long enough to reach anywhere on the tank's sides and upper hull would have to be quite long and of sufficient build to support its own weight and that of the patch; the servos would have to be quite powerful to maintain stability with the tank bouncing across broken ground. Both of these necessities mean that the whole assembly will be quite bulky. Finally, the module would have to be situated so as not to obstruct the rotation of the turret.

The best scheme would be to place it on the turret itself, but the only two practical locations, the back or the top, both present challenges. Installing the module on top of the turret would interfere with the commander's line of sight, raise the overall height of the vehicle, and expose the module to enemy fire (meaning that it will have to be armored and thus even more bulky). Installing it on the rear of the turret will interfere with the loading and operation of the tanks main gun magazines, and of course the entire module would be lost if one of the magazines were penetrated, since they are designed to explode outward when hit in order to save the crew and the vehicle from complete devastation.

This is an interesting idea, but there isn't nearly enough meat on the bones.
-- Alterother, Nov 29 2012


Please, please - allow the cool tones of pure reason to clarify matters. First, consider armor. It is to keep something outside from coming through and hurting those within. If the something comes in, it comes in through a hole in the armor. Now the robot arm: presumably this is because having a person scramble out of the tank exposes this person to hurtful things on the outside. But those robot arms: they will easily be blown up or captured with lassos, and if they go rogue they will give you a wedgie.

The solution: have the person safely inside the tank apply extra armor on the inside of the weakened spot. People are good at putting things on other things. Hurtful things trying to gain entry thru a previously damaged spot will find new and undamaged armor beneath. A stash of spare 1 cm armor plates would serve well to keep the dirty magazines from sliding around inside the moving tank.

A fake robot arm atop the tank might still be useful. It could be inflatable to give the illusion of huge muscles, and would mostly perform culturally-appropriate rude gestures.
-- bungston, Nov 29 2012


para-armour, perhaps?
-- 4whom, Nov 29 2012


Erm, yes: what happens when the robot arm get hit? Wouldn't that be the first thing people would aim for?
-- mitxela, Nov 29 2012


Chobham covers a wide range of ceramic armor.

The M1A1 is supposed to be ~700mm equivalent against HEAT, 600 against APFSDS, so 2-3 feet, not one.

The key question is whether the robot arm+spares weighs more or less than simply thickening up the armor in the first place.
-- MechE, Nov 29 2012


// Wouldn't that be the first thing people would aim for? //

Probably not. The idea behind most penetrative anti-tank weapons is a one shot kill. Those with the means to pierce the armor of a tank (AT rockets, recoilless rifles, or really big guns) typically try to hit the engine in the rear of the hull or the magazines in the rear of the turret. Barring that, they'll go for the thinner armor on top of the turret or the flanks; a frontal shot is a last-ditch resort. Those without a penetrating weapon are going to go after the tracks in order to immobilize the tank. Either way, it makes little sense to attack the self-repair mechanism first when you can just attack the tank and then, if need be, have a better shot at the repair arm in its vulnerable deployed state.
-- Alterother, Nov 29 2012


Chobham is a composite armor formed by spacing multiple layers of various alloys of steel, ceramics, plastic composites, and kevlar, giving an estimated maximum (frontal turret) 1,320–1,620 millimetres (52– 64 in) of RHAe versus HEAT (and other chemical energy rounds) and 940–960 mm (37–38 in) versus kinetic energy penetrators. The depleted uranium underlay adds 610 mm to that. (linky)

RHA was some of the best steel of the world war II era, which makes it good but not excellent compared to modern steel.

The arm would be at risk when deployed but the idea is to use it when the tank is stopped between battles for a quick patchup, not in the heat of battle.

A patch on the inside wouldn't work because A: the crew can't get to all areas of the tank that need to be armored and B: the weakened place on the armor probably doesn't represent full penetration. If something gets all the way through the crew is probably dead.
-- Voice, Nov 30 2012


At some point in the process the manipulator has to give an appropriate hand signal in the direction of the enemy.
-- FlyingToaster, Nov 30 2012


Well it should be capable of flinging poo anyhow.
-- 2 fries shy of a happy meal, Nov 30 2012


Just a question about patches - I don't know much about armor, but I'm thinking a patched-on cover over a blast-blemish in the steel/ceram/plast sandwich will still be a notable weak spot.

So - what about a patch that covers the hole, but also has a standoff cage and internal deflector plate that will make it difficult for another incoming round to get a clean hit on the same spot?

Really, I want to post some sort of suggestion for a powerfully-magnetized Roomba-tankmech-R2-droid low-profile thing that can lock down your power couplings, replace armor and jettison parts cannisters while you're shooting/scooting. But... I won't.
-- lurch, Nov 30 2012


//        The arm would be at risk when deployed but the idea is to use it when the tank is stopped between battles for a quick patchup, not in the heat of battle.    //

In that case, wouldn't it be easier for a crew member to just jump out and apply the patch by hand?

RHA is a reference to a manufacturing process--Rolled Homogenous Armor. Rolled homogenous steel, while not typically used for tank armor these days, is still good stuff. However, the RHAe is still based on the medium-carbon steel used in WWII. Modern RH steel is available in a wide array of alloys.
-- Alterother, Nov 30 2012


Thinking about tanks - the problem is the people in there. Without them it would be a lot tougher. I wonder if there are drone tanks? Maybe the antenna apparatus is not durable.
-- bungston, Dec 03 2012


//Thinking about tanks - the problem is the people in there. Without them it would be a lot tougher. I wonder if there are drone tanks? Maybe the antenna apparatus is not durable. — bungston//

When the Stryker was marketed, it was supposed to have an unmanned variant. It never materialized, however.
-- Kansan101, Dec 03 2012


There are drone tanks in the works, but there are a number of reasons why the idea takes a lot of perfecting, most concerning the gun. A tank on the ground is much more vurlnerable than an airborne drone, and far greater a liability. If it malfunctions or is compromised by the enemy in some manner, much hilarity could ensue. The Defence Department does not like the idea of "rogue 120mm smoothbore levels town" going viral on YouTube.
-- Alterother, Dec 04 2012



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