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  #51  
Old 11-16-2016, 07:54 AM
Gunslinger Gunslinger is offline
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Originally Posted by Precambrianmollusc View Post
The question here though is 'what is sufficiently big?' . Clearly by definition anything that is 'sufficiently big' will do what it is sufficient for .
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In the case of artillery, probably anything over 100mm, maybe 155, these days. The rock would have to be really big, given that a lot of the effect of AP shells (and HE from above a tank) has to do with sectional density (i.e., putting all the pressure on a small area), and velocity is a lot more effective than mass.

Assuming a spherical lump of granite ... screw it, let's compare things I know: a 12-pounder cannon in Napoleon's time had a bore of 121mm, fired a cast-iron round ball weighing (duh) 12 pounds (4.1kg) at 439m/s. It'd chip away at a stone wall or penetrate a foot or so of oak, and could reach out to 1400m.
The WWII German 12.8cm PaK 44 fired a 28kg shell at 950m/s, and could penetrate 200mm of 30-degree-sloped armor at a thousand meters.
The Rheinmetall 120mm on the Abrams fires an 8kg lawn dart at 1700m/s, and can (probably; the actual numbers are classified) shoot through 560mm of armor at 2km.

I'm not an engineer, but that seems to indicate that it's not really possible to build a trebuchet (at least out of wood) that could throw a rock big enough to hurt a modern MBT.


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Originally Posted by bump View Post
I always thought the loader was the lowest guy on the crew totem pole. as loading the gun and manning a mg is a little less skilled than actually driving the tank.
Could be, it's been awhile since I read about it. Counterpoint, driving is easy, just turn in the direction the TC tells you to (it's not so much "driving" as "semi-autonomous remote control unit"-- tank drivers can't see for crap, they're mainly there to keep from running into things directly ahead when the commander is otherwise occupied and can't actively guide them), as opposed to slamming cartridges the size of your thigh into the breech of a gun as fast as the TC can call out targets. Maybe you're thinking of WWII and I'm thinking of modern, and the roles have swapped, what with modern tanks being easier to drive, faster to shoot, and no longer needing a part-time mechanic as part of the fighting crew.

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Originally Posted by Chronos View Post
Can the top-ranked guy in the tank change the duties around if he wants? A cousin of mine is a tanker, and has made his way up to fairly high rank (Lt. Col., from what I'm told), so I'm presuming that he would be the boss in any tank he's in... but that cousin absolutely loves to drive, and is quite good at it. Would it be allowed/acceptable for him to just say to the low man on the totem pole "Move over; I'm taking the wheel" (or whatever it is that a tank has)?
The commander of an individual tank is usually a CPL or SGT (the LTs and CPTs of a tank company are also TCs, for obvious reasons), and yeah, one would assume they rotate the crew around regularly when not expecting combat, if only to keep their filling-in-for-a-wounded-guy skills up, or to train for the next job up the line (say, let the Gunner poke his head out the top while the TC gets a nap in the gunner's seat on a long march).

But like Muldoon said, an LTC's up at the level where they're at best riding around in the backseat of a HMMWV well behind the armor, their job is strategic. Which is not to say an LTC could pull rank and tear it up on the training range, but never while deployed.

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Originally Posted by Kedikat View Post
I've had thoughts about using super adhesives as weapons. Shoot a shell or missile that splatters on impact and the adhesive seeps into turret ring, maybe gun mechanical bits, hatch crevices ( can't get out ).
Much more effective and arguably cheaper to just slap a shaped charge into it and break things, alas.

Quote:
A non moving tank might be permanently immobilized if hit in the drive wheels and tracks. Some adhesives are very thin liquids that like to seep into crevices and set. They can resist tons of force.
The Soviets accidentally used this to great effect in WWII -- German Tiger and Panther tanks had several rows of closely-spaced overlapping roadwheels that, when fighting in Russia, tended to get packed full of mud during the day's driving. The mud then froze when they stopped for the night.

But that was more annoying than anything -- a couple hours with blowtorches or the like to get everything freed up and start rolling again. It's extremely difficult to permanently kill a tank -- as long as it can be recovered and hasn't melted into a heap of slag, it can be fixed.
  #52  
Old 11-16-2016, 09:34 AM
Machine Elf Machine Elf is offline
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Originally Posted by JerrySTL View Post
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.
Helicopters have firing rates that low, but fixed-wing aircraft fitted with guns are generally capable of thousands of rounds per minute. The GAU-8 Avenger, fitted to the A-10, is good for 4200 rounds per minute. test firing here; you don't even hear the individual rounds, you just hear a loud buzz at about 70 Hz.
  #53  
Old 11-16-2016, 10:07 AM
Gunslinger Gunslinger is offline
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Originally Posted by Machine Elf View Post
Helicopters have firing rates that low, but fixed-wing aircraft fitted with guns are generally capable of thousands of rounds per minute. The GAU-8 Avenger, fitted to the A-10, is good for 4200 rounds per minute. test firing here; you don't even hear the individual rounds, you just hear a loud buzz at about 70 Hz.
Yeah, but they're not going to hit the same hole in the armor and dig through, those 50-80 rounds in a typical burst might hit the tank. (IIRC, the GAU-8 and most fighter-jet 20mm Gatling guns carry enough ammo for maybe ten seconds at max cyclic rate -- the Warthog, with it's 4200 RPM, carries 1174 rounds-- it's very much the same as the infantry rifle firing in three-round bursts from a 30-round mag and hoping one will hit and knock out the target. As opposed to the ship-mounted twin/quad Bofors 40mm AA guns and truck-mounted quad .50s which put up a literal wall of steel/lead; the airplane guns are more in the spirit of bomb CEP than of actual aiming.)

Last edited by Gunslinger; 11-16-2016 at 10:07 AM.
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