In Gurps, how powerful do you need to fight a tank?

[Varyon]

Originally Posted by Anaraxes

The diameter of the steel pin holding track shoes together on the Abrams is 1.374 inches. If you can bend or break that, you can get an "M-kill" on the tank. (If the tank moves with "only" a bent track, it'll likely just tear its own track off.)

Such a bar has DR 30 and HP 60, per the tables on B558.

Supers rules for bending bars make it a Quick Contest of ST versus the higher of the object's HP or HT; DR subtracts from ST before the Contest. So, Lifting ST 90 gives you a 50-50 shot at breaking a track. That's ST 20 + 9 (Super-Effort). ST 20+10 gives you a value of 120, so 90 vs 60, guaranteed other than crits.

Breaking a tooth or three off the drive sprocket would be similar, as the teeth are individually about that same size. They poke between the gaps in the track shoes, so I wouldn't think they'd be particularly easy to get a hold on. But if you're imagining just grabbing the edge of the track and pulling it outward, you don't really care which part breaks.

Tracks are typically tensioned with a force equal to around 10% of the weight of the tank. They're not stretchy or loose (or at least they're not supposed to be), so you can't just slip the track off the wheels without physically breaking the track --or loosening the idler wheel so you can get the tension off the track with enough slack to just lift it over the retaining edge or sprocket teeth. Breaking a drive/idler/road wheel or axle would be harder than just breaking the track.

Do you know if there's anywhere in the tracks where you could just shove your arm in and get it stuck (and mangled if you're a normal human), akin to the spokes of a tire? If you've got enough DR to tank (heh) a cannon to the chest, the tracks would probably break before your arm would even be harmed (at least if it's general-purpose DR), and even if not the tank is just going to be stuck going around in circles with one set of tracks unable to move.


With that much general-purpose innate DR, one thing that might work for you would be to get enough levels of Super Jump to be able to Slam into tanks hard enough to break through their side armor. Combined with Walk on Air and a somewhat-lenient GM, you can even target the top armor, which will be a lot more vulnerable (basically, you jump up to a bit above the tank, plant your feet on solidified air - or however you justify Walk On Air working - while upside down, then before gravity takes hold you jump off again at full speed toward the top of the tank; you can't really rely on just falling really far unless you're also superdense, as a human-shaped and human-weight object in a dive has a terminal velocity of only around Move 100, which means dealing only 1d cr per HP). I'm not sure how the top armor compares to the armor on the treads, however - if a mobility kill is sufficient, you may want to go that route instead. Super Jump is actually a pretty cheap way to get high damage*; it normally has the drawback that you also take that damage, but if you've got enough DR to handle an anti-tank weapon, you've probably got enough DR to smash through a tank without injury.

*A standard human long-jump has a maximum distance of 7 yards, and every level of Super Jump doubles this - but you use the higher of Basic Speed and 1/5 your maximum long-jump distance to determine the speed. Wrecking a tank by going through it's front armor on an average damage roll calls for around 500d (actually more like 485d, but we'll round up; note I used Anthony's suggestion of dealing 200 HP Injury past 1500 DR for this). For a character with HP 10 to do this (assuming they have enough DR to survive), they'd need to be moving at around Move 5,000, around Mach 13.3. That calls for a long-jump distance of 25,000 yards, or Super Jump 12 [120] - a steal compared to the [2500] base for a 500d cr Innate Attack, but then you need even more points than that invested in "can survive Slamming into a tank at Mach 13.3," but if you've already got that going for you, might as well capitalize on it, right? Alternatively, you pay another [60] for Bouncing +50%, in which case a successful Jumping roll lets you simply bounce off the tank without taking any damage - although then you have a ~1.5% chance of pulping yourself in the attempt (thanks to a failed Jumping roll - I assume anyone who opts for this is going to have Jumping 16 or higher). As a bonus, because you retain IIRC 90% of your velocity on a bounce, you should be able to readily hit the side (or top with the Walk On Air option) of the tank - jump to land right beside it (or just above it), then bounce off the ground (or air) and slam into it. I'd personally assign a -2 to the relevant Jumping rolls for this (like a tic-tac), but that's cheap to overcome (of course, if you're really skilled, you could do a Rapid Strike to bounce between multiple tanks, wrecking all of them). And of course you don't need nearly as much damage if you're intending to go through the side or top armor.

EDIT: I'll note that I'm not a fan of how Bouncing works, as it feels rather broken, but I've confirmed with Kromm that the above is how it's meant to work. Personally, I think I'd rather interpret it as downgrading the slam to be one that is at however much speed you lost in the bounce (10% by default, but I think the wording of Bouncing says "up to 90%," so you could opt to adjust this for a given slam), but also give the option to make this a shove (deals no Injury, but deals double Knockback). So if you have HP 10 and slam into something at Move 5,000, then bounce off at Move 4,500 (losing 10% of your speed), that only results in a Move 500 slam. That's either 50d cr to each of you, or 50d cr dkb to just the target. Against a ~200 HP tank, that latter option will shove the tank back a couple yards (the former option probably won't damage it at all - unless you targeted the top armor perhaps, I forget how much DR that has - and knock it back about a yard... but unless you've got some serious DR of your own, you're probably pulped).