I am wondering how effective a 20mm AP cannon would be against the sidal armour of an M1 Abrams original. How about a .50 caliber gun against the rear ventilation port of an Abrams? What about with AP sabot rounds?
Not just bullets either. How badly would pouring boiling oil from a medieval castle wall damage a modern MBT? Or what about throwing a large rock at it from a catapult?
Could you detonate a HE shell inside it’s barrel by shooting at it down the barrel? Or stabbing it with a knife? Can you damage the barrel itself by shoving a knife down inside? I read that this is possible on a Quora post with 80 or so upvotes.
Pretty sure a 50 cal machine gun isn’t liable to do much to a M1, except mess up the optics.
A 20mm gun isn’t liable to do much to the side armor; even the vaunted 30mm Avenger cannon only penetrates 76mm at 300m, and it’s *designed *to kill tanks. A 20mm round probably does less damage at the same range, and the M1 probably has more than 76mm worth of protection from the side.
Boiling oil probably wouldn’t do much unless you lit it, and then it would effectively be the same as a molotov cocktail.
A rock wouldn’t do much, even if fired from a trebuchet.
I suppose you could mess up a shell and the barrel, but I dont’ think you’d kill the tank unless you got lucky and rolled your grenade down the barrel as they opened the breech.
The wikipedia article on the M1 Abrams has some pretty interesting reading on damage to various tanks, the causes, and the results. History of the M1 Abrams - Wikipedia
A 20 mm cannon would not penetrate the side armor. While there have been a huge number of 20 mm cannons through the years, none of them offer that sort of penetration. WWII cannons with specialized ammunition might penetrate 40 mm of armor. Armor Penetration Table
The fuse isn’t active when it’s in the barrel so simply hitting the fuse isn’t enough at that point. Despite the fuse being at the tip (and other places like on the 120MM MPAT) the detonators aren’t. Short of hitting the detonator I wouldn’t bet the impact from a small arms round is enough to cause it to explode. Also unless the gun is pointing directly at you the round is likely bouncing on it’s way down the barrel further reducing the energy. If it’s not concentrating on a target they are about to engage, the barrel is moving around too if they are at all expecting a threat.
Put the last two points together. You really only have a decent shot to try when the barrel is pointing directly at you and the tank is about to engage.
Is your name Mister Fantastic? Do you have a similar super power? If not your arms aren’t remotely long enough to stab the round.
I’m not sure that any knife you’ll likely have is harder than the surface hardness inside the barrel. The grooves of the rifling are quite a bit deeper than any small scratch you’d get in quickly anyway.
Leaving it inside might work. Something like jamming the tube into mud fully obstructing the barrel tends to result in the barrel needing replacing if the crew fires before cleaning it out. I’m not sure something as small as a knife would be a big enough obstruction. Feel free to try. Be aware the crew will still have a tank that, other than the main gun, is probably fully functional. That crew will be pissed. Not as pissed as if you shot their cooler and sleeping bags up but still…
While a single 20 mm round probably wouldn’t do much harm, I wonder about multiple impacts at the same spot? Many aircraft can shoot hundreds of rounds a minute. Of course the tank and aircraft are probably both moving (especially the aircraft) so hitting the same spot more than once could be problematic.
But what if the TANK was thrown by a trebuchet and it flew and tumbled waaaaaaaay away, and landed on its tracks? I don’t fancy the crews’ chances, but could the tank survive that?
Is the impact of that qualitatively different from a nearby explosion (e.g. neighbouring tank blown up by pouring coke and Mentos down barrel)?
Man I’d like to see the trebuchet capable of hurling over 60 tons of tank. The counterweight alone would have to be…what…minimally 2,400 tons and probably closer to 6,000 :eek:?
During the early stages of the Eastern Front of World War 2 German 37mm anti-tank guns were completely incapable of penetrating the armor of Soviet T-34 tanks, to the point that one of the Soviet T-34 strategies of dealing with 37mm AT guns was to simply charge them and run them over to conserve ammo since they offered no threat to them. KV-1 heavy tanks also reported incidents where hundreds of 37mm rounds hit them frontally or on the side and the tanks were completely fine. Since modern tanks have many times the protection of those tanks I doubt multiple 20mm hits would do any damage at all except maybe from the very top.
Are you sure? Tank armor is designed to protect against HEAT and sabot rounds. A large rock is a very different attack. According to wikipedia, the largest trebuchets could launch a 90 kg rock up to 300 meters. That’s an impact velocity of 54 m/s or 120 mph. I wouldn’t be surprised if having 200 lb of rock hitting the top of a tank at 120 mph did a lot of damage.
The Abrams has a smoothbore main gun. Not that it matters - you’re not going to be able to do anything to the bore with a knife that will affect it.
[QUOTE=Wikipedia]
In 1421 the future Charles VII of France commissioned a trebuchet (coyllar) that could shoot a stone of 800 kg, while in 1188 at Ashyun, rocks up to 1,500 kg were used.
[/QUOTE]
Now we’re up to 1.5 tons. Which is a lot less than an 60-ton tank, but the falling impact is going to be a lot more than 1.5 static tons.
I’m no expert, but my wild guess is that a direct hit wouldn’t smash the tank flat, but it would have a good chance of messing up the turret bearings, suspension/treads, gun barrels (main and machine), and anything else sticking out of the main armor box.
Surface hardness of the M1A2’s M256 120mm L/44 gun’s chrome plated lining is currently (?) around 900-1100 on the Knoop hardness scale. As chrome plating, and specifically hexavalent chrome waste, leads to a bit of a toxic waste issue, the US Army is investigating other methods of surface treatment for large gun barrels like the M256. One of those methods involves sputtering either Tantalum or Chromium onto the surface of those barrels. Measured hardness from either of those sputtered materials is around 200 Knoop (or HK), which is evidently hard enough for the purpose. (See Slide 18 of the linked document.) Without this coating, ultra-high speed kinetic energy penetrator shells like the M829A3 would wear out the barrel in, ballpark, about 150 shots. (Slide 3) FWIW, the A3 looks to be much rougher on the barrel than other ammunition. 5700 FPS comes with a price.
Anyway, kitchen knives’ hardnesses are often measured on the Rockwell C scale. 55-60 is typical, though modern powdered metal blades can get higher. Converting between the two scales shows that 55-60 HRc is about 600-700 HK. So, I don’t think the knife would scratch the older barrels, but it might scratch the newer sputtered ones.
As to penetrating the armor on a modern MBT with multiple smaller impacts, I’ll link to this oldie-but-goodie, the A-10 Pilot’s Coloring Book, circa 1977. Not because it’s all that helpful in answering the question, but it does show that answering “will it penetrate or not?” really depends on where the tank is struck. I have read accounts from Bradley crew that they were able to penetrate the armor on T-72 on down with 25mm sabot ammunition and judiciously selecting where to shoot the tank. I haven’t read of sabot ammunition available for the 20mm x 102 rounds the U.S. M61 rotary cannon uses. Which strikes me as strange, given sabot AP ammunition exists for smaller cartridges like 12.7 and 7.62 mm. I wonder if it’s because 20mm is primarily an aircraft or anti/aircraft weapon for the U.S., and sabots are either unneeded to damage aircraft, or pose a FOD hazard when shot from aircraft?
Moreover, sabot ammunition isn’t the most friendly to use in a combined arms environment; flying sabot petals evidently pose quite the risk to infantry operating in front of the gun muzzle. (Range safety document, with more info than probably you want on surface danger zones for a large variety of ammunition. From it, at page 98, even plastic sabots from 25mm shells are dangerous up to 100m downrange, and up to 50 m to the side of the muzzle.) Still, if you need to punch through armor, there’s no substitute for speed, and sabot rounds are faster than everything else.
As far as the trebuchet and rock go, don’t tanks often knock down trees while maneuvering in forests? Are tanks often damaged by tree tops falling onto their top armor?
The rock would definitely not do any damage to the armour itself. Back of the Envelope calculations only, but the 1.5 ton rock would impact with ~2,000 Kj of kinetic energy. A modern sabot round I believe delivers in excess of 12,000 Kj of kinetic energy. Which depending upon where you hit it, an M1 can shrug off.
As you suggest, some of the components might suffer, and I suspect a shaken up crew, but good luck hitting a mobile target like a tank with a trebuchet anyway.
20mmx102 APDS rounds exist; they are the standard ammo for the 20mm Gatling gun as used in the Phalanx shipboard terminal missile defense system. They aren’t used in a/c guns for the reason you stated. In a few freak cases modern fighters have managed to fly into the path of their own 20mm projectiles, not to mention a cloud of sabot petals rapidly decelerating in the a/c’s path.
Anyway even with a stationary gun against a stationary target, there is enough dispersion in the trajectory from round to round to make it unlikely to hit ‘the exact same spot’ (say we define that as a difference of some small % of the round’s diameter). And Gatling guns have a larger dispersion when the barrel is moving perpendicularly to the axis of fire at a varying speed as the gun spools up at the beginning of a burst (eventually it’s constant and can be corrected for by the same degree on each shot). Some dispersion is fine; the optimum dispersion is generally greater than zero in multiple rounds against a moving target, but hitting right on top of a previous hit is not likely.
In some actual cases though antitank rounds defeated armor they were theoretically incapable of penetrating by nearby hits causing the armor to shatter. You can find pictures of armor of German tanks in WWII defeated that way by theoretically overmatched Allied antitank rounds. Of course it also might have meant the armor wasn’t produced correctly. And it’s not directly relevant to modern tanks where protected by heterogeneous armor arrays rather than steel plates.
The highest penetration performance quoted for any 20mm rounds are for 20x139 APDS types as fired by the Rheinmetall Rh202 on for example the German Marder Infantry Fighting Vehicle. That’s 60mm per the Wiki page, 44mm at 1000m by other sources.
The lowest value I could find for M1 armor is from a Russian site’s diagram showing only 30mm of steel on the lower hull side behind/beneath the skirts, and also meaning the round has to thread its way through the closely spaced road wheels. And it’s just somebody’s official looking diagram of classified info.
This Steel Beasts game specification shows a very narrow zone of 50mm protection just below the side skirts
But in both regards, penetration and protection, there’s now a parallel world of values programmed into games which the game programmers try to verify in the real world, but they must come up with some detailed specification either way. The game values are often the product of discussion among people who know what they are talking about, in general technically, but who aren’t divulging classified info. It’s not necessarily crudely made up stuff by people with no idea what they are talking about. Many such learned discussions occurred over the years here for example, though this forum is not what it used to be: http://www.tank-net.com/forums/index.php?act=idx
(somehow the site also now generates an unsafe site warning. I’ve never had a problem, but I’m not telling anyone to proceed to it if not comfortable doing so)
Anyway, these numbers are people’s estimates, possibly in some cases actual info which has leaked, but I’m not saying it’s the absolute fact, and I’d recommend against people who know it’s not correct from their own knowledge of classified info speaking up and saying so, even just to say that.
Practically speaking 20mm guns have negligible capability v modern well protected tanks. US claims against Iraqi tanks in 1991 even with 25mm in side shots is not to my knowledge solidly documented. There’s a surprising lack of detailed public info on actual weapons effects and causes of Iraqi tank losses after all this time, besides certain well known photos which speak for themselves.
I was just coming back to mention that since I had both slicks and A1s (and later) floating through my head based on the OP. I defaulted to the gun all my Table VIIIs were on.
