How does a tank round create this sort of vaccum?

This sounds almost unbelievable to me. Almost. Anyone care to explain the physics of this?

Well, I’m prepared to call BS.

When a big blast goes off, first you get the initial shock wave, then a big column of smoke and dust rises. There’s a strong wind toward the center of the blast to replace the air that went up. I do not know if that wind would be enough to “suck guerrillas out from their hideaways,” though.

I was watching a documentary about the battle between the Hood and Prince of Wales and the Bismarck and the Prinz Eugen.

One of the descriptions the German sailors (survivors from the Bismarck) used about the giant shells that were passing overhead was that “they ripped a scream from your lungs.”

I would sincerely doubt it, but I think it will be easier to prove it correct by way of verified anecdote than to prove it wrong via calcs. Or, that is, more straightforward. And until I see a verified as true anecdote, it sounds like perhaps a reporter took an exaggeration too seriously.

I’d have to see a picture of all the furniture that got sucked out of buildings, and similar tornado-like damage before I gave the report any credibility.
Lightning, which heats air to ~8000 degrees doesn’t generate winds that suck people out of their hideaways. Why would a much slower 120mm tank round ?

I know when I was in the Army, I was stationed at a proving ground that tested a lot of heavy weapons (they tested the flechette type rounds there…nasty little things). One of the guys was telling me about a new tank killing round. It was supposed to be a high velocity DU round that was shot through the fuselage of the tank. the resulting change in air pressure was supposed to either cause an implosion in the inner chamber (ie where the gunner and spotter sit) or cause the crew members to be sucked out “an itty-bitty hole”. While this may make more sense in a tank that is sealed from the outside air supply with negative pressure, like in the Abrams, I’m not quite sure how this would work in an environment outdoors.
Of course, I’m not a physics type person…so I can’t quite qualify it with any calculations.

Sounds like a lot of hyper BS to me…

I am absolutely unqualified to answer, but…

Have you ever stood by the side of a road when a large truck went by? There is a “blast” of air that is being pushed out of the way by the truck. Then as the truck passes, there is a suction behind it. The same thing happens when you use a paddle in water. There is a wave in front of the paddle, and eddies behind it as the water rushes forward to fill in the “hole” cause by water being displaced. It seems to me that a 120mm high velocity round would be displacing a lot of air, creating a partial vacuum behind it. Would this vacuum be sufficient to “suck guerrillas out from their hideaways into the street”? I have no way of knowing; but there would be some vacuum behind the round, as well as a shock wave before it if the round is supersonic.

Does lightning have mass?

It sounds like a game of “telephone” to me. Someone who knows what a mile-per-second twenty pound slug of metal sounds used a phrase like “pulled 'em right out of their positions” to a reporter. The reporter then took that literally and with a smidge of poetic license filed his or her story.

There is a shock wave that is no doubt disconcerting, but a vacuum there is not.

I find this very difficult to swallow for two reasons:

  1. It would make far more sense to keep the tank interior at positive pressure to reduce the chance of biological or chemical agents entering the compartment. Negative pressure is used in biological facilities to keep potentially deadly organisms in, which is the opposite of what you’d want in a tank. I’m not qualified to say whether or not a tank is kept at any pressure differential at all, but if it were going to be, positive pressure would make the most sense.

  2. I can’t see any sort of projectile causing a sufficient pressure differential to force a human body through a relatively small hole or cause the tank crew copmpartment to implode (or explode, for that matter). In fact, I’ll go so far as to say this is completely impossible. It’s already been noted that high-velocity projectiles do produce a partial vacuum in their wake, but even a complete vacuum inside the tank wouldn’t cause implosion, and you’d need a large overpressure inside to force a man through the hole created by the round, and there’s no mechanism for that.

But wait a minute. I saw Goldfinger this one time at band camp? And I swear that’s what happened…

I went through a rapid decompression once.

Hi. M1A1 tanker here.

The first anecdote; about sucking guerrillas out of their postions, is complete nonsense.
The second, about sucking crewmembers out of a 25mm hole in the turret is also nonsense. Q.E.D. is right about positive pressure. However, that only occurs when there is a threat of Nuke/Bio/Chem weapons being used. At all other times the loader’s and commander’s hatches are open. You can see a lot more that way.

I’ve heard about crewmembers being sucked out before. Many times, and from other soldiers. They claim they have seen a video that shows sheep, goats, or chickens sucked out. I have never seen a video like this and I love watching anything about military equipment. I think it is the military equivelant of an urban legend.

Yes, soldiers will repeat rumors as gospel. You WOULD NOT BELIEVE how many soldiers knew the guy in Desert Storm who got a video of his wife screwing another guy. It usually ends with her saying to the camera “I want a divorce”. EVERYBODY knew that guy!