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Decompression

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Flash
27988.  Sun Oct 23, 2005 5:35 pm Reply with quote

Although 'decompression' starts with a D, this strikes me as a classic GI question:

Q: What happens if you fire a bullet through the fuselage of a pressurized aeroplane?

F: Decompression / You get sucked out through the hole

A: Not much, apparently. This was tested in Mythbusters Episode 10
Feb. 22, 2004. They concluded that: "The pressure is not high enough and the hole is too small. Even when a sizable hole was blown in the fuselage with explosives, the rush of air was nowhere near powerful enough to suck Buster out of the hole."


Last edited by Flash on Sat Nov 12, 2005 5:53 am; edited 1 time in total

 
JumpingJack
27991.  Sun Oct 23, 2005 5:44 pm Reply with quote

Flash,

I've never heard that you'd get sucked out through a bullet hole, I'm afraid, so it wouldn't do a lot for me.

Also, we probably ought to avoid research from other QI related TV shows, don't you think? I thought the plug for Brainiac looked a bit naff in retrosepct and unworthy of us.

(My fault, I know, I fully supported, even pushed for, the question...)

 
Flash
27994.  Sun Oct 23, 2005 5:51 pm Reply with quote

I think that if you ask your next dinner party what they think will happen if a hole gets blown in the fuselage of a plane (it can be quite a large hole, not just a bullet hole) you may find that this notion is quite widespread. It gets used in films a lot, anyway. We wouldn't need to quote Mythbusters - I haven't researched it, but I bet there are scientific sources which have debunked it.

Incidentally, I agree that we should avoid using other shows' footage.

 
Flash
27995.  Sun Oct 23, 2005 5:54 pm Reply with quote

If this one did make the cut, this is for the notes:

Conversely, Hollywood would seem to be right about hiding from bullets underwater. High velocity bullets disintegrate in less than 3 feet of water, and slower velocity bullets (eg pistol rounds) slow to non-lethal speeds after travelling through 8 feet of water.

 
Gray
28010.  Sun Oct 23, 2005 9:14 pm Reply with quote

I thought the 'sucked out of plane' thing was genuine. I suppose, then, that people just suffocate instead if they're at high enough altitude.

There is 'explosive decompression' though - where the rush of air out of a hole in less than 0.1 seconds (and the shock of the pressure change on the plane fuselage) causes it to break up. Slower than 0.1 seconds is called 'rapid decompression'.

This is well documented for e.g. Turkish Airlines Flight 981, from 1973, where six people were sucked out of a suddenly ruptured cabin door.

Explosive decompression to the human body (i.e. falling out of your space suit) is called 'Ebullism', and looks nasty if it's over more than 1 atmosphere drop (although the human skin can actually stand a vacuum, it appears - GI question there?).

These engineers have managed to stem the tide of explosive decompression in seals:
Quote:
Explosive decompression can happen when any gas filled fluid is passing through an elastomer seal.

When the pressure inside the seal fluctuates inappropriately between high and low, massive heat can build up, inducing the oil or gases flowing past the seal to molecularly migrate into the seal's polymer material, eventually causing it to rupture.

 
Flash
28023.  Mon Oct 24, 2005 4:24 am Reply with quote

Quote:
human skin can actually stand a vacuum, it appears

I wouldn't have guessed that - so if were you thrown out of a spaceship without a space suit you'd remain intact? Would your body decay in space, or would the bacteria all die as well? If they did, does it follow that a dead body in space would remain intact and uncorrupted indefinitely?

 
Gray
28026.  Mon Oct 24, 2005 4:41 am Reply with quote

I think some bacteria can freeze for infinitely long - look at those dug up and reanimated from ice cores that have lain dormant for tens of thousands of years.

It sounds like you wouldn't explode in space, although I expect your lungs and brain would try to get out through your nose after about 30 seconds. It wouldn't, I guess, be a very attractive corpse. I suppose there must be gaseous cavities that would expand horribly. Moral: never take off your space helmet if you have wind.

 
eggshaped
28028.  Mon Oct 24, 2005 4:56 am Reply with quote

This is from Straightdope:

http://www.straightdope.com/classics/a3_147.html

Quote:
...the medical literature suggests this view is exaggerated. For one thing, I have never seen anything indicating your eyeballs would explode (although your eardrumms might burst). It's true that in the absence of ambient pressure your blood and other bodily fluids would boil, in the sense that they would turn to vapor. But that's not as drastic as it sounds. Your soft tissues would swell markedly, but they'd return to normal if you were recompressed within a short time.

It's conceivable your lungs might rupture, since in a vacuum the air in them would greatly expand. But experience suggests this is rare even if decompression is extremely rapid. The chances are much greater if your windpipe is closed, making it impossible for the expanding air to escape.

Death would not be instantaneous. It's believed you'd have 10-15 seconds of "useful consciousness" and it'd be several minutes before you'd die. If you were rescued within that time there's a decent chance you'd survive. Research with chimps and monkeys suggests that if you were exposed to a virtual vacuum for less than 90-120 seconds you might not suffer any permanent damage.

That said, there are circumstances involving explosive decompression in which your body might be torn to bits. This would result not from the exposure to a vacuum per se but from injuries caused by the accompanying air blast.


Also as an aside, there was this major decompression accident in the 80s, at the Byford oil rig, here’s Wiki’s take on it.

Quote:
At 4:00 AM on November 5, 1983, four divers were in a compression chamber system attached to a diving bell on the rig, being assisted by two dive tenders. One diver was about to close the door between the chamber system and the trunk when the chamber was explosively decompressed from a pressure of 9 atm to 1 atm in a fraction of a second. Five of the men were killed; the other was severely wounded.

Diver D4 was shot out through the small jammed hatch door opening, being ripped apart. Subsequent investigation by forensic pathologists determined that diver D4, being exposed to the highest pressure gradient, exploded with violence due to the rapid and massive expansion of internal gases. All of his thoracic and abdominal organs, and even his thoracic spine, were ejected, as were all his limbs.

Simultaneously his remains were expelled with force through the narrow trunk opening left by the jammed chamber door, less than 60 centimetres (24 inches) in diameter. Chunks of his body were found scattered about the rig. One part was even found lying on the rig's derrick, 10 metres directly above the chambers. His death would almost certainly have been painless and instantaneous.

Medical investigations were carried out on the four divers' remains. The most conspicuous finding of the autopsy was large amounts of fat in large arteries and veins and in the cardiac chambers, as well as intravascular fat in organs, especially the liver. This fat was unlikely to be embolic, but must have "dropped out" of the blood in situ. It is suggested that the boiling of the blood denatured the lipoprotein complexes, rendering the lipids insoluble.

The rigor mortis was unusually strong. The hypostases (accumulations of blood in internal organs) were light red, and in two cases there were numerous hemorrhages in the livers. All the organs showed large amounts of gas in the blood vessels, and scattered hemorrhages were found in soft tissues. One of the divers had a large sub-conjunctival bulla (a blister in the tissue of the eye).


http://en.wikipedia.org/wiki/Byford_Dolphin

 
Gray
28030.  Mon Oct 24, 2005 5:06 am Reply with quote

Now that's just nasty.

 
Flash
28035.  Mon Oct 24, 2005 5:16 am Reply with quote

I can think offhand of two film scenes with people bursting apart under decompression - one of the Timothy Dalton Bond films in which Roberto Davi uses a decompression chamber to execute an associate, and the end of Total Recall, when three of the characters are ejected out of the side of a mountain on Mars.

 
Gray
28040.  Mon Oct 24, 2005 5:33 am Reply with quote

I thought it made Arnold Schwarzenegger look slightly better, actually.

 
MatC
49964.  Thu Feb 09, 2006 10:28 am Reply with quote

On a related topic - I can’t find the cutting right at this eon, but apparently the answer to the question “What would happen if someone opened the door while the plane was flying?” isn’t “He’d be sucked out,” or even “He wouldn’t, actually, be sucked out,” but “You can’t open the door while the plane’s in flight: the variable pressures make it physically impossible. So worry about something else instead.”

 

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