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What would happen to occupants of an O'Neal Cylinder if it suffered a massive hull breach on one of its ends i.e. the base of the cylinder? Specifically, those nearer to the breach.

If the breach occurred catastrophically (explosion or some kind of hull failure) what would those near it experience? Say the failure occurs at "ground level" of the station and is a hundred or so meters across and a few dozens high.

  • Would there be a real legitimate risk of being violently sucked out as so often inaccurately depicted in movies?

  • In the violent outrush of air how severe would the pressure drop be?

  • Would that outrush of air reach supersonic velocities?

  • What would happen to a lake or ocean located nearby?

  • What other effects, if any, can be expected?

I know due to the massive size of the station it would likely take a long time to vent atmosphere through a breach even a hundred meters across. For the majority of the population, there would be plenty of time to get to safety or a repair mechanism to close the breach. I'm only concerned with those unfortunate souls near by.

Edit: Links to resources that can help me find the answers are perfectly acceptable.

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  • $\begingroup$ What's the hole size and how far from center do you want it to be? $\endgroup$ – Mołot Nov 23 '16 at 19:14
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    $\begingroup$ Call it one hundred meters long by forty meters high, and right on the inner surface of the cylinder. $\endgroup$ – Joe Kissling Nov 23 '16 at 19:18
  • $\begingroup$ If nobody will, I'll try to do my math when I'm home. $\endgroup$ – Mołot Nov 23 '16 at 19:21
  • $\begingroup$ I've got the free time, what resources should I look to for the proper mathematical formulations? $\endgroup$ – Joe Kissling Nov 23 '16 at 19:23
  • $\begingroup$ too late, it seems all I would think of and more is already in the answer. $\endgroup$ – Mołot Nov 23 '16 at 21:56
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So for my rough estimate I'm going to use Bernoulli to approximate, as outlined below. (This assumes the fluid is incompressible which doesn't really apply to air terribly well, and assumes a steady state of flow which given a large enough O'Neil Cylinder and a small hole would likely apply.)

Bernoulli Equation

Using derivation 4, assuming initial velocity is zero, air density and initial pressure are Earth normal (1.225 kg/m3 and 101 kPa) and final pressure is zero (vacuum of space) we can find the final velocity is calculated to around 400 m/s or 900 mph.

This is a really, really fast wind speed, faster than hurricanes (74-160 mph), even faster than tornadoes (upper end around 300-400 mph) and faster than the speed of sound at sea level pressure (768 mph)

Now this would not actually happen, if we look at our assumption, we assumed air was incompressible, it is compressible. The limit to how fast air would move is the speed of sound, waves won't go faster than that in air without something directly pushing it. 768 mph is still pretty amazingly fast, not something you would want to be too near (wind speed would drop off farther from the hole.)

This would definitely be fast enough to suck people out. From XKCD's what if series, in wind speeds over ~120 mph it's impossible to stand and you would started sliding and getting pulled out the hole.

Other than the high wind speeds, air pressure would begin to drop in the cylinder around the hole, temperatures would lower, clouds would form, it would be very similar to a large low pressure storm system on Earth.

Larry Niven's original Ringworld novel featured a hole into space which caused a constant storm centered on the hole.

With regards to local lakes or oceans, they would either freeze from the temperature drop, or boil from the pressure drop depending on how far from the hole they are (boiling closer to the hole and freezing further away and generally getting blown around by the giant winds, it might look a little like a giant snow globe.)

Depending on the relative sizes of the habitat and the hole this storm could last for a long time or immediately suck the entire atmosphere out in one blast at the speed of sound. Either way definitely a bad day.

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    $\begingroup$ I guess I should have given Bernoulli more credit, I was not a fan of the incompressible assumption. But it seems to be a fairly good approximation. $\endgroup$ – Joe Kissling Nov 23 '16 at 19:53
  • $\begingroup$ Lots of thermal capacity in a body of water, not even counting the state change to ice. Atmosphere will be gone for a long time before a lake freezes. Even with boiling away a lake in vacuum it will take significant time to freeze -- just like people don't turn to ice when exposed to space. Sure, it is really cold, but heat transfer rate in a vacuum is poor. $\endgroup$ – Gary Walker Nov 24 '16 at 5:50
  • $\begingroup$ Yup my answer was basically going to be " the same as what happens on a Ringworld" plus the passage about the storms in Ringworld. $\endgroup$ – Ash Sep 5 '17 at 11:35
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Josh King gave a good answer about the air, but a more pressing problem might depend on exactly where the hole is in relation to the spin axis of the cylinder.

The Island 3 configuration is actually two counter rotating cylinders to maintain their long axis pointed at the sun to gather solar energy for industry and agriculture. if one cylinder is breached off axis, the cylinder will be unbalanced and begin to wobble or precess around its spin axis, putting considerable stress on the cylinder itself (a composite construct of concrete, glass and reinforcing steel cables under tension, much like a suspension bridge). Since the cylinder is relatively long and slender, the sudden torques caused by precession around the axis could conceivably buckle the cylinder, causing catastrophic failure.

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Island 3

Even without a catastrophic failure of one of the cylinders, the unbalanced cylinder will be putting a tremendous amount of stress on the coupled cylinder and the mechanisms which link them together. The inhabitants will be feeling a "spinquake", which will be somewhat like having an unbalanced load in a conventional top loading washing machine during spin cycle. Depending on the structural details of internal fittings, buildings etc. there could be a lot of internal damage as things are shaken apart.

The emergency procedure if one of they cylinders becomes unbalanced might well be to cast off the second cylinder to isolate it from shaking forces, and hope that the stricken cylinder does not fail catastrophically. If it does, large pieces will be propelled at high velocity into the other cylinder, destroying exterior fittings as a minimum (the large mirrors and agricultural cylinders on the outer rings) and potentially breaking reinforcing tension hoops and breaching the structure of the cylinder itself as a worst case. Given the size and mass of each cylinder, it is safe to assume there is no way even a decoupled cylinder could move far enough away to avoid being destroyed in the hours or days it might take for the first cylinder to shake itself apart.

So the true threat to the colony could well be mechanical failure as the system becomes unbalanced.

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  • $\begingroup$ Any ideas on how long this unbalance would take to get out of control? The sheer size and mass of the cylinder compared to the breach I described should take a while. I'd also expect some sort of compensating system in the cylinders, perhaps the billions of listers of water that could be used as shielding can also used to as some kind of balance. $\endgroup$ – Joe Kissling Nov 24 '16 at 19:23
  • $\begingroup$ Without any real parameters it is impossible to say. The structure is strong in tension against rotational forces, but since it is a long tube with relatively thin walls (as a percentage of overall size) it might be very easily "buckled" under unbalanced forces. The usual descriptions of these things assume the structure itself is massive enough to provide shielding, as well as being able to deal with the internal movement of people and vehicles, so counterweights, ballast tanks etc. will need to be something you explicitly build into the story. $\endgroup$ – Thucydides Nov 24 '16 at 21:22

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