But that bleed-air is initially coming from the outside, too, isn’t it? Is it HEPA-filtered or something?
You can attach reactive armor modules on top of the main armor of the tank. They’re not armor in the traditional sense so much as active point defense systems.
If you go way up thread, the Abrams uses some on the side skirts. Other tanks use differing amounts and configurations.
That bleed air is is pulled off after the combustion stage of the turbine, and it burns off something like 99% of chemical contaminants. The cooler/filter system takes care of 99% of that 1%. So you’re breathing filterted, chilled turbine exhaust. The engine pulls more air through than it needs to combust the fuel, so there’s plenty of O2 to suck off and use for crew purposes.
When I say “chilled,” it’s not air conditioning by any stretch of the imagination. But when it’s 120* F inside the turret, even 80* F air feels blissfull.
So a fire attack of some sort would have to suck up enough air to snuff the engine in order to suffocate the crew.
Another way to take down an Abrams is water. The engine air passes through three particle separators: the mesh screens over the air intakes, a pre-cleaner which is an oblong box (roughly 3’ x 2’ x 8") containing a stack of several thin metal plates with air holes in them, offset one from the other, and finally, there’s three large paper filters called “V-Packs.” Get those wet enough and you’ll stall the engine out.
Most “water casualties” are self-inflicted by none-too-bright tank commanders telling their drivers to take less-than-optiimal routes. On my first deployment to Grafenwoehr Training Area in Germany, my TC had me drive through what he thought was just a big puddle. Turns it it was a very big puddle, and deep, too, with delusions of being a small pond.
Fortunately I was going fast enough that when we hit, it displaced a lot of water, and we were through and out before it could surge back and fill the hole created by our entry. Otherwise, it would’ve had definitely surged back high enough to suck water into the engine and soak the V-packs.
I know this because some knucklehead in Third Plattoon tried the same thing, but wasn’t going fast enough to clear the puddle before the backsurge swamped him.
So the OP could outfit his [del]suicide squads[/del] combatants with large water balloons and super-soakers. Get enough water on the left-center-top of the hull, and you have one stalled Abrams.
OK, so you have two guys, one civilian carrying a bucket of paint on his way to paint a house, and one guerrilla carrying a bucket of paint who, as he walks past the tank, throws it all over the sensors and periscopes. Which one do you shoot before he gets close enough, and why?
Tell both to stay the fuck away (and emphasize it by pointing large, black, fully-automatic, belt-fed bullet-chuckers at them). The one who doesn’t run away in terror but instead screams “DIE! DIE! DIE!” as he runs at you with the bucket of paint is your enemy.
!BLAM! Problem solved.
Seriously, why would the tank crew sit still long enough for someone to get in range with something like that (much less an effective AT weapons of some sort)? Do you seriously think tank crews (military combatants) in a hostile/war zone are going to be idiots? Not establish a perimeter? Not stay on alert/watch? Let any schmuck just diddy-bop into effective range?
Not to say it can’t happen; in an insurgeny/counter-insurgency type conflict, sheep and goats get hard to tell apart. But a sufficiently alert/paranoid crew of soldiers are not likely to get caught flat-footed by some mook with a bucket of paint strolling by their vehicle within effective paint-throwing range.
I doubt it would do anything much, since superglue has a low shear strength and the tank has an enormous amount of torque. Tossing a bag of thermite into the works though, that might work. Even if it probably wouldn’t be able to melt through the armour it could fuse the mechanical parts together and make it near impossible to repair in the field.
Buckets of honey… Come on…Come ON…COME ON!!! ABORT ABORT!!
Goat bomb; hmm…
Except that most of the wars we find ourselves in nowadays seem to be insurgency-type conflicts. When you bring your tanks into the city of a putative ally, you can’t just order everyone out of the city for the sake of your tanks. If you’re going to go to measures like that, then you don’t really even need the tanks at all: Just warn everyone to evacuate the city, and then send the B52s in to flatten the place. Contrariwise, if you intend to leave it as a functional city, then you can’t stop the people just going about their daily routines.
Lumpy didn’t specify a terrain in his OP; the tank/Cavalry doctrine I was brought up with (admittedly 20-years old) didn’t put tanks in close-quarters/urban terrain for counter-insurgency “peacekeeping.”
Even so, I doubt that even U.S. Infantry squads at checkpoints in Baghdad let just anyone stroll up on them without exerting some sort of control over the situation. As we well know, that doesn’t always work with a suicidally determined adversary.
If you do put a tank as a heavy-firepower backup at some sort of urban checkpoint, it’s going to be great big fat immobile target; tough, yes, with lots of firepower, but a large stationary target nonetheless. With my Cavalry background, sacrificing mobility is a cardinal sin, right up there with screwing the Commander’s virgin daughter.
Satchel charges, RPG attacks from hides, etc., can all take a vehicle crew by surprise, or wear them down under the draining tension of having to be constantly aware of everything in their immediate environment.
But since Lumpy also didn’t specify what type of scenario his game would take place in, it is altogether possible under the “Might Makes Right” rule that yes, the occupiers of a city can order its inhabitants to alter their daily routines to such an extent as, “Under penalty of death, do NOT approach closer than 100 meters to a military checkpoint unless ordered to do so by said checkpoint.”
For the OP, isn’t there a “banned book” of some sort, written by a US citizen, that outlines how you can take down big American tanks without the tools a soldier might otherwise rely on? I can’t remember the title, and I don’t think it’s the oft mentioned Anarchist’s Cookbook. Worth Googling for if you’re better with search terms than I am.
It’s mentioned in a lot of the documentaries on tank warfare I’ve seen.
The Wikipedia article for the 8th King’s Royal Irish Hussars in Korea mentions the tankers’ response to the Chinese infantry trying to overrun them;
The thread is starting to sound like a guide on surviving an attack by Daleks 
FTR, We were discussing a cross-country journey through a “semi-apocalyptic”* American midwest.
If your Cavalry background includes screwing the Commander’s virgin daughter, you ought to tell us about it sometime. 
*For those who careOk, what the heck is “semi-apocalyptic”? We’re still hashing out the details but the baseline scenerio is that terrorists turned loose a genetically engineered plague which almost, but not quite, brought down civilization. A provisional government mostly run by the military has restored civil order on most of the East Coast, and has at least the formal alligiance of some enclaves on the west coast. In between, a chain of military forts and depots in the middle of a chaotic midwest controlled by local factions of varying degrees of friendliness or hostility. The idea is that our tank is part of a convoy that was sent cross country to “show the flag” by some genius with too many stars on his shirt. We can (almost) always obtain enough fuel, and ammunition is plentiful (though not limitless), and we will even have a few opportunities to obtain spare parts for the engines and tracks. The one thing that is not going to be available is any way to repair damaged armor; whatever damage we take is there to stay.
In that scenario, you’re biggest limitation is going to be the wear and tear on the tracks and the drive train. Tanks aren’t built for long road trips. As far as protection, you should survive pretty much anything short of a really big IED.
Unfortunately (or, perhaps, fortunately!) I have no personal experience in this regard. And no Cavalry background is required; general military will do just fine.
I like the concept. May I offer some suggestions?
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The crew picked for this tank should be “elite,” as such things go. “Best-of-the-best,” and all that.
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Fuel and other petroleum products are going to be the biggest concern; Abrams are Capital-G Gas Guzzlers, and require near-constant top-up of TurboShaft synthetic turbine oil, and you’ll also n eed some 30W for the tranny, suspension, and final drive. You’ll either have to have fuel-depots/supply points in friendly hands every 250 miles or so, or a couple of fuel trucks in the convoy.
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Parts will be another big concern. I’d recommend one complete FUP (Full-Up Pack) which is an engine/transmission combo. Lots of spare ammo, too. And a maintenance crew as part of the convoy as well.
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Ammo loadout: unless there’s something you’re not telling us, typical AT munitions (Sabot, HEAT) probably won’t be as necessary. You’d probably load out more general and anti-personnel munitions (HEP, Beehive/flechette).
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Personal arms: most tank crews are armed with a sidearm (1911 .45ACP in my day, M9 9mm nowadays), with a single M-16 issued as a “crew” weapon. I’d up that to an M9 for everyone, an M-4 for the driver, gunner, and commander as well for dismount, and an M-16w/M203 grenade launcher for the loader. Change the loader’s MG from the vehicle-mount only M240 to a hybrid M-249 SAW that can be used either vehicular and dismounted.
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Cumulative damage to armor: I’d say you’d need 100mm AT guns or higher to actually stress the armor enough to worry about “cumulative damage” to the armor. RPG-29s, AT-4 (both Swedish and Soviet models) for rockets to “cumulatively” damage the armor. That’s assuming hits on the thickest armor (front turret and front hull).
What if I’m at the top of a flight of stairs? Tanks can’t go up stairs, right?
In regards to the road trip and the lost armor, you can always try Hillbilly Armor as a sort of duck tape repair. The stuff won’t be as good as dedicated armor by a longshot, and if you use it the wrong way, it may actually be dangerous to you, but I’ve heard of welders coming up with some clever supplementary armor solutions, such as cage armor, which basically projects the outer shell of the armor out a foot or two, in order to prematurely set off shaped anti-armor warheads before they can contact the actual armor. The effectiveness of it depends a lot on what the bad guys are shooting at you, I don’t think it has much effect at all on Explosively Formed Penetrators or kinetic penetrator rounds.
But yeah, as far as disabling a tank without dedicated anti-tank weapons, it’s mostly just going to come down to a shovel and a saw, digging tank traps and camouflaging them against detection. Mind you, many things tanks can get themselves stuck in, other tanks, or even dedicated tank extraction vehicles, can pull them right back out of (kinda makes you wonder if tanks getting bogged in deep puddles and the like happens a lot :D)
Oh, and those dedicated tank extraction vehicles are built on tank chassis themselves, as I recall they remove the turret and put some cranes and other tools on them. I wouldn’t bet on them being much easier to take out than a tank itself would, aside from the much more modest firepower at their direct disposal.
There’s a picture of an M1 that got penetrated below the skirt armour by a 14.5mm AP round.
Also the sighting systems and sensors are vulnerable to anything 20mm or over.
Which mind you, is still a pretty big freaking gun, especially compared to anything that infantry tend to carry. Do any modern armies even issue anti tank rifles any more?
Most of my experience is with bonding aluminum to aluminum, but I’m sure there is some adhesive that would strong enough, but I don’t know if there is anything that would cure fast enough.
We’ll have a few tanker trucks (can you say “highly flammable target”?) and the assumption is that we’ll be able to get more supplies as we go along (and of course, to assume makes an ass out of u and me)
There are some bases out there run by colonels of somewhat dubious loyalty, plus all those people claiming to be the Freestate of Cumberland or such. We’re taking some AT just in case.