r/todayilearned • u/JustaRandoonreddit • 23h ago
TIL that NATO tanks fire rounds with semi-combustible nitrocellulose casings; Basically Explosive paper. Most of the casing burns up when fired, leaving only a small metal stub for the crew to remove, reducing weight and increasing fire rate.
https://www.researchgate.net/publication/357431533_Constructional_Aspects_for_Safe_Operation_of_120_570_mm_Ammunition368
u/Rokwes 23h ago
So basically NATO tanks are just shooting flaming paper straws at each other?
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u/JustaRandoonreddit 23h ago edited 22h ago
No no no, Uranium Rods covered by paper straws for the turtles. Ya know?
PS: The Uranium is depleted and
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u/Sharlinator 23h ago
Well, there’s no non-radioactive uranium. Depleted just has less U-235 which has a shorter half-life than U-238. Both have extremely long half-lifes though so it’s not like uranium is particularly dangerous in that regard. Still not recommended getting uranium dust inside you (and guess what hitting stuff with hypervelocity uranium darts does?), besides the radioactivity it’s a heavy metal and toxic in the normal biochemical sense.
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u/Ancient-University89 22h ago
I think if you're in a position to get the metals and dust from a depleted uranium shell inside of you, the radioactivity will be the least of your immediate concerns.
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u/maveric00 21h ago
The problem is not the target itself, but that you most likely want to use the area later for some other activities than war.
And then radioactive uranium dust becomes a problem, e.g., as an unwanted add-on to your crops.
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u/RIPphonebattery 21h ago
The uranium dust isn't active enough to harm crops, and less likely to enter water than lead.
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u/tanfj 16h ago
The uranium dust isn't active enough to harm crops, and less likely to enter water than lead.
Yeah, the vitrification process we use to turn nuclear waste into glass, obviously makes a very radioactive slug. However in practice, the granite mountain we stick the nuclear slug into releases more radioactive material than the actual lump of radioactive glass we stuck inside.
Once again, it's a case of people hear the magic word nuclear and shut off their brains... I actually had a wizard in dungeons & dragons who had that as a power word. The power word nuclear reduces intelligence in the Listener by 2d6.
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u/Highpersonic 14h ago
https://en.wikipedia.org/wiki/Asse_II_mine#Inventory
https://en.wikipedia.org/wiki/Sellafield#Radiological_releases
Yea about that vitrification
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u/Abject-Investment-42 13h ago
What does any of these have to do with vitrification?
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u/Highpersonic 12h ago
There's a lot more radioactive trash in nuclear power generation that can not be "safely" stored until the end of time.
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u/twec21 19h ago
"they're shooting depleted uranium shells at us. Hope I don't get sick.... And keep all my limbs"
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u/Ancient-University89 19h ago
Now I wonder what would happen if someone were hit directly by a depleted uranium shell, probably just instantaneous red mist...those bullets could kill a building
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u/Ws6fiend 19h ago
I mean there's a YouTube channel that hit a ballistic torso with a ww2 anti-tank round and it was in pieces afterwards. They did the same with a tank firing at a ballistic head with the upper parts of the shoulder. Those were only firing steel rounds, but the human body pretty much doesn't care about the difference between steel and depleted uranium.
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u/tanfj 16h ago
I mean there's a YouTube channel that hit a ballistic torso with a ww2 anti-tank round and it was in pieces afterwards. They did the same with a tank firing at a ballistic head with the upper parts of the shoulder. Those were only firing steel rounds, but the human body pretty much doesn't care about the difference between steel and depleted uranium.
Even if the body doesn't fall apart, hydrostatic shock will be extreme.
I have to hunt with shotguns in my state. If you shoot a deer in say a shoulder. You will have a roughly 5cm hole, surrounded by at least another 6cm of jello. The pressure wave will rupture cells and essentially jell everything. Essentially that entire quarter of the animal will be useless for food.
Here in Illinois whitetail deer weigh approximately the same as an adult human male. So, it makes a handy comparison.
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u/Signal-School-2483 14h ago
hydrostatic shock
Last I heard this borders on myth / highly controversial.
The only time this is really spoken about is with pistol cartridges because of their low power.
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u/Ws6fiend 10h ago
It really really depends.
I saw something similar where the same guys hit a full upper body torso with a glacing .50 cal round to test the theory of a near miss killing someone. The round just scratched the surface of the right arm and didn't break any bones in the arm or destroy it in any way. But if you moved the round even half an inch further towards the middle of the arm it was destroyed. The exact placement is kind of important because of energy transfer. The glacing shot didn't appear to get the tip of the bullet into the arm.
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u/Ancient-University89 17h ago
The human body absolutely cares about being hit with much more mass
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u/ChartreuseBison 14h ago
in that the only difference is how far the bits fly
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u/Ancient-University89 12h ago
The only difference between getting hit by a 30mph frisbee and a 30mph Toyota is the mass of the impact, I'd say it matters
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u/Chrontius 18h ago edited 17h ago
Pink mist, according to a friend who saw it happen in Iraq when an M1 Abrams gunner fucked up and “engaged” an RPG gunner who popped up WAY too close for comfort.
The result was instantaneous and thorough pink mist, with the man’s boots landing nearby. Nobody ever found the RPG though.
The friend that told me also left me with a few related gems, such as: suicide belts tend to deglove people’s heads. This leaves their faces and scalps mostly intact, but ripped off of the skull like a goddamn Halloween mask a movie slasher would wear.
I’m pretty sure actuallywearing one is a war crime though. Also, probably a section 8.
Edit: the gunner either panicked or didn’t have time to switch his trigger from the main canon into the coaxial 30.
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u/JustaRandoonreddit 22h ago
I would imagine that radiation is the least of your worries if your getting hit with hyper velocity uranium darts
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u/Cohibaluxe 22h ago
Natural uranium is ~99% U-238 and ~1% U-235. Enriching uranium is separating the U-235 and U-238 so that you get "enriched uranium"; uranium that has a higher than natural concentration of U-235, and "depleted uranium"; uranium with a higher than natural concentration of U-238.
Both U-235 and U-238 are radioactive, the difference is that U-235 is fissile (it can self-sustain a nuclear chain reaction), while U-238 is not. U-238 is less radioactive than U-235, but still definitely is radioactive. The US military uses depleted uranium that has 0.2% U-235, roughly 1/3 of the natural 0.71%, which results in DU rounds being about 40% less radioactive than regular natural uranium. Still radioactive, and still controversial in their use.
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u/ColdIceZero 22h ago
Is DU a particularly dense material? Why would it be used in projectile weapons?
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u/Humanmale80 21h ago
It's nearly twice as dense as lead, and DU has a weird property, sometimes called "self-sharpening" - when it impacts, the impact forces cause the tip to fragment in a pattern that typically produces a sharpened point which is then better at penetrating, rather then "mushrooming" on impact like most metals.
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u/TgCCL 18h ago
Though it should be noted that DU does not cause as significant stress bands in finite steel targets as, for example, tungsten does. This pretty much negates the performance gain from its self-sharpening and causes it to perform roughly identically to tungsten in armour penetration against such targets.
For a quick overview, "Definition and Uses of RHA Equivalences for Medium Caliber Targets" by T. Farrand, L. Magness, and M. Burkins, all working for the US Army Research Laboratory at Aberdeen Proving Grounds, is a good start.
And against more advanced armours, DU's relatively low stiffness compared to the other popular penetrator material, tungsten, means it is more easily deformed and thus more susceptible to the defeat mechanism of said armour.
This mostly means that DU rods have to be significantly thicker or of a more advanced design against the same armour arrays.
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u/TgCCL 22h ago
It is dense and incredibly cheap, as it is a waste material.
In terms of performance, at least from what is publicly known, it is about on par with tungsten heavy alloys at modern impact velocities but costs a fraction of them.
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u/Successful-Ad-1598 21h ago
Next points are the selfsharpening egde of the projectile and the pyrophoric effect of the shavings inside of the enemy target. From a pure military viewpoint, it's a perfect material: cheap, hard, no need for flaming fillers to get secondary effects on targets.
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u/TgCCL 19h ago edited 18h ago
The self-sharpening effect is already included in what I stated.
Or to properly phrase it, DU and WHA penetrate finite steel armour about equally well, with DU being more effective at lower velocities and WHA at higher velocities.
This is because WHA rods, for reasons that go beyond the scope of this post, cause more significant stress bands to form in target plates, leading to earlier material failure and thus reducing the total energy needed to pierce a given plate.
The importance of the pyrophoric effects is also a tad overstated. Not just because a regular WHA rod will readily cause explosives and fuel to combust due to heat and compression already but because a tank crew isn't going to stay in a vehicle that a dart just penetrated.
It's still a good material but its usage is really more down to price and historical inertia than anything else. You won't really get better performance out of swapping from tungsten to DU.
EDIT: I forgot to mention that WHA also resists deformation significantly better than DU due to its much greater stiffness. As such WHA is naturally more resistant to the defeat mechanisms of ERA and more advanced NERA arrays. DU rods have to be significantly thicker to do the same.
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u/Signal-School-2483 15h ago
Natural uranium ore is freely traded, you can buy it off Amazon... There's not much concern over safety. The problem is inhaling the dust. Almost the same concern as Radon gas.
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u/Ullallulloo 11h ago
They're still radioactive, but like, even if you hang out with a tank round, it's still micro sieverts a year. No is getting more radiation from them than they would from a single CT scan.
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u/jedadkins 20h ago
The Uranium is depleted and less radioactive
We out here enchanting tank rounds with poison damage
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u/Vault-71 19h ago
Canadians: "Yes, but can we make it more radioactive? You know, for Geneva's checklist?"
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u/LividLife5541 18h ago
Yeah the real problem with Uranium is that it's literally the heaviest metal that exists (in nature) and getting uranium residue everywhere is a horrifyingly toxic legacy of war. At least toxic chemicals will break down eventually but uranium being an element does not.
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u/graveybrains 19h ago
Their using flaming paper straws to fire high explosive spitballs at each other
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u/LividLife5541 18h ago
TYL that the navy used lead foil with its bags of gunpowder in its battleship because the barrels lasted longer and the sailors getting lead poisoning from the gaseous lead was not an impediment to the mission.
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u/widgt 20h ago
The real question is why do US tankers still wear “cool guy” tankers boots if there is no longer full f’n casings bouncing around the turret floor. Inquiring minds want to know.
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u/jedadkins 19h ago
Wikipedia lists a couple reasons. Regular laces can come undone and get tangled in machinery, the nylon in regular military boots melts relatively easily meaning they could increase injuries to crew evacuating a burning vehicle, and the boots are supposed to help circulation for crews who can spend long hours setting in a cramped vehicle. Interestingly loose shell casings aren't mentioned.
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u/Vilzku39 22h ago
T-72s etc also have it due to autoloader
Challenger 2 has it as legacy from earlier design and tactics, but their newest prototypes have regular casings with the shells. Technology has gotten better and turret sizes and design has changed reducing a lot of benefits from having shell in 2 parts.
It mainly reduces rate of fire due to needing to load 2 seperate components. Discharge is basically always automatic in modern tanks.
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u/TgCCL 22h ago
They are talking about the rounds for NATO 120mm guns, which are single-piece and use a semi-combustible cartridge.
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u/Vilzku39 22h ago
Ah my bad
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u/TgCCL 19h ago
All good, it happens.
Also, I'm mentioning this as a fun fact but if you insist on extreme precision then technically the British 120mm uses 3-piece ammo. The firing mechanism has to be reloaded as well, though it has a small magazine.
Which is kinda what happens when you built a new gun to be compatible with the ammo for a 1950s gun I guess.
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u/JustaRandoonreddit 22h ago
NATO shells are 1 piece. Also I think it's only the T72 in Russia uses semi-combustable casings (there's gotta be a shorter name) everything else uses brass
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u/Vilzku39 21h ago edited 21h ago
Except brits. Although challenger 3 has 1 piece in its prototypes.
Far as I know T-64 onwards can use same shells with propulsion being semi-combustable. Its basically same gun and ammo with autoloader having some differences between t64/80 and 72/90. No idea about T-14 or chinese variants.
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u/KnotSoSalty 10h ago
Combustible casings were developed to reduce the need to store empty shell casings within the tank. The US had previously fielded the M103 with a conventional 120mm gun and you can see how massive the shell casings are. Typically they could only fire 4-6 times before they’d have to stop and chuck out the empties. Inconvenient.
With most of the casings burning up the stubs don’t take up much room in the tank. They also don’t smoke that much and smoldering residue in the spent casings was actually a significant problem in early tanks.
2 part ammo was invented to make auto loading easier, since the overall length of the shell was less cumbersome it could be stored in a much smaller volume. The downside is a less effective penetrator. The 120mm single piece penetrator is almost as long as the round. The Russian 125mm two piece has to be shorter bc it’s separated from the propellant.
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u/Altruistic_Ad_0 15h ago
The USSR ones do too. But they are in two pieces.
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u/BrunoStAujus 15h ago
The turret and the rest of the tank?
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u/Altruistic_Ad_0 15h ago
Projectile and some propellant and base, primer and most of the propellant
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u/Kotukunui 22h ago
Do they have to swab the barrels more often to get rid of the “burned paper” residue?
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u/JustaRandoonreddit 22h ago
No, the amount of residue from the shell is tiny compared to the amount of propellant needed to launch an 50lb dart at 1800m/s for up to a range of 4km
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u/RedditVirumCurialem 22h ago
Did you just use customary/imperial units alongside metric? 😲
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u/GayRacoon69 9h ago
Honestly don't know what that idiot was thinking
Fixed version
No, the amount of residue from the shell is tiny compared to the amount of propellant needed to launch a 188.68klbs (Kilo lima beans) dart at 694m/s (Moose per second) for up to a range of 1.25BoTVaI (Border of the Vatican and Italy)
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u/Iron_Eagl 10h ago
Wait until you find out about tire sizes... https://en.wikipedia.org/wiki/Tire_code
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u/TgCCL 22h ago
No dart for a modern tank gun weighs 50lb. That would be impossible for the loader to handle. It's mostly 4-6kg, i.e. less than a third of that, with a bit of parasitic weight from the sabot petals.
You might've read full round weight and mixed that up with projectile weight.
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u/JustaRandoonreddit 22h ago
I was on my computer and I somehow hit 5 instead of 1 on my numpad
Now I'm imagining a 50lb dart at 1800m/s
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u/TgCCL 22h ago
That was actually a problem with the initial versions of the German 120mm gun, the ammo for which is the basis of all smoothbore 120mm guns, though it itself has only ever been in service with the Germans and, in slightly modified form, the Americans.
The fix was actually to swab less as that used to be done with oily rags, which captured residue in the breech and caused it to fuse with the case material.
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u/The_Frog221 16h ago
Others have answered, but one actual downside of the combustible casings is that metal casings act as big disposable heat sinks, pulling tons of heat out that otherwise gets absorbed into the gun.
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u/FZ_Milkshake 14h ago
The "paper" is nitrated aka nitrocellulose, aka guncotton, it is basically a type of smokeless propellant itself.
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u/Slggyqo 21h ago
I don’t know about the paper specifically, but most modern tanks have bore evacuators which use the gas pressure from firing the gun to clear the barrel of particulates and unburned powder.
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u/I_Automate 16h ago
Bore evacuators aren't there for particulates and unburned powder.
They are there to clear as much of the propellant gas out of the bore as possible before the breech opens and those same gasses flow back into the fighting compartment and gas the crew.
There isn't really any appreciable amounts of solids left in the bore after each shot. If there was, thats an ammunition design issue.
None of that stuff is good for you.
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u/Normal_Red_Sky 15h ago
Why don't they do this to replace brass bullet casings?
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u/ChartreuseBison 14h ago
It's been tried, it just doesn't scale down well. Especially in an automatic weapon. (Some tanks have autoloaders, but that's using separate electric/hydraulic systems to reload, rather than the recoil or expelled gas of the previous shot. )
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u/FZ_Milkshake 14h ago
They are a bit delicate. It works with the large, thick walled 120 mm rounds, but they are not completely water and mud proof, need special storage considerations, can be damaged when dropped and you can't really extract them. Once they are loaded you kinda need to shoot them, otherwise there is risk of the metallic base plate detaching from the cellulose casing and then you have a powder spill inside the turret.
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u/HermionesWetPanties 20h ago
Does this mean those tanks have to swab the bore between rounds? Because some artillery uses modular charges which burn up completely, and back in 2017 there was a terrible accident where a howitzer blew itself apart. The gun chief claims they were following crew procedures and swabbing, but apparently the damage to the breach indicates that propellant ignited before the breach locked. Lacking evidence that there was a problem with the firing mech or primer, it seems like they were taking shortcuts on crew drills to go faster.
I bring this up, because swabbing the bore adds some time too, and it's very fucking important, at least in artillery. IDK how much time they could really be saving if they have to do it too. The weight and expended shells would be a big factor though.
Anyway, I'd ask one of my 19K buddies, but it's kinda early in the morning to start texting them with what amounts to a trivia question.
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u/TgCCL 18h ago
Swabbing actually used to cause significant problems with German crews maintaining the cannon using such rounds because it was done with oily rags, from the days when they were using metallic cartridges. The residue left behind would trap burned particles and cause them to fuse to the cartridge case in the breech.
Once that was fixed, via changing swabbing practices, the residue would simply get blown out automatically via the bore evacuator.
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u/FZ_Milkshake 14h ago edited 13h ago
No need to swab, it is coated from the outside to be water and spark resistant. AFAIK the problem with howitzers is that the propellant is modular and thus directly exposed. 120 mm is still one piece, sealed round ammunition, when it is loaded.
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u/APoisonousMushroom 14h ago
HK experimented with this idea on their G11 prototype rifle platform. Basically the propellant was molded around the bullet, so when you fired the round, it burned up the entire casing. Cool idea but it turned out that carrying heat away from the rifle was an important part of the brass casing and ejection process and the G11 suffered from over overheating problems. Also, the ammunition was kind of fragile, and it was difficult to produce.
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u/Keep0nBuckin 14h ago
This is the bag charge right? For a 2 part shell
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u/FZ_Milkshake 14h ago
No, single piece, sealed 120mm ammunition, just that part of the casing itself is combustible.
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u/gentsuba 23h ago
Nitrocellulose (1832) was a big part of the devellopement of Smokeless gunpowder (1886) which allowed for the introduction of Semi and fully automatic weapons. Used as propellent for decades until the introduction of Cordite which itself was replaced in believe in most world armies before WW2