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  #1  
Old 07-28-2002, 05:20 PM
Jet Jaguar Jet Jaguar is offline
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Skydivers don't breathe?

On National Geographic Explorer this weekend, they did a bit with a skydiver who trained a falcon to jump with him, in an effort to determine the falcon's top speed in a dive.

Anyway, on one of their bumpers to commercial, they claimed that a skydiver can't breathe during freefall. They said it wasn't necessary anyway, because the skin will absorb enough oxygen from the air. Furthermore, they claimed that the reason skydivers don't jump on cloudy days is that the condensation on their skin would suffocate them.

This sounds like total B.S. to me. It sounds a lot like the Goldfinger "painted skin" myth. I imagine not jumping on cloudy days has more to do with seeing the ground than suffocation. Plus I know what water drops feel like on a motorcycle at 65 mph, they probably pack quite a sting at 120 mph. Any skydivers care to confirm/deny/comment?
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  #2  
Old 07-28-2002, 05:36 PM
Mangetout Mangetout is offline
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It isn't true; it's been addressed here on the boards before (along with the myth that skydivers can't jump when it's raining as they would injure themselves on the pointy end of the raindrops).
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Old 07-28-2002, 05:39 PM
Gut Gut is offline
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Here is an old relevant thread. It's definately not true. You are also correct about water drops packing quite a sting at 120mph.
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Old 07-28-2002, 05:40 PM
Mangetout Mangetout is offline
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(although if they are jumping from really high up, they can't breathe and would have to wear special apparatus; does anyone know if they ever jump from just above the altitude where normal breathing is possible and just hold their breath until they fall into breathable atmosphere? (sounds exceptionally risky due to the risk of blacking out and not being able to pull the cord, unless your chute is deployed automatically at a certain altitude)
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  #5  
Old 07-28-2002, 05:44 PM
Boyo Jim Boyo Jim is offline
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I have real trouble believing that National Geographic would put out such crap. Are you sure that's where you saw it, and not a "factoid" piece produced by some idiot, and aired by the station alongside the NG show?

OTOH, the "Goldfinger" painted skin thing is essentially TRUE. Your body must sweat for temperature regulation, and having all your pores sealed could kill you.
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  #6  
Old 07-28-2002, 05:50 PM
Mangetout Mangetout is offline
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Quote:
Originally posted by Gut
You are also correct about water drops packing quite a sting at 120mph.
I would imagine so (I have travelled at over half that speed in the rain on a motorbike and it hurt a little then, but raindrops aren't pointy (that's the myth part); also the raindrops are falling too, so you aren't hitting them at your descent velocity.
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Old 07-28-2002, 06:09 PM
Sam Stone Sam Stone is offline
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I know this is radical, esoteric science, but the producers of the show might be interested to learn that human beings do not breathe through their skin.
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  #8  
Old 07-28-2002, 06:09 PM
Gut Gut is offline
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I only fell through the edge of a cloud and still felt little stingy bits on my face. I bet going through the centre of a cloud or actual rain really stings.
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  #9  
Old 07-28-2002, 06:36 PM
Mangetout Mangetout is offline
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I suppose falling through a cloud of hail (especially if it was still forming and not actually falling) would be pretty rough.
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  #10  
Old 07-28-2002, 06:53 PM
Gut Gut is offline
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LOL. That would really suck. You couldn't even react as you would on the ground if you got hit with something. i.e. grabbing at the spot that hurts. You'd mess up your stable freefall and go all wonky. Besides you'd be grabbing at almost everything. Maybe it would be best to just curl up and wait to be through the cloud and resume a stable position. Although the general rule is no falling through clouds.
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  #11  
Old 07-28-2002, 07:25 PM
Exapno Mapcase Exapno Mapcase is online now
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Quote:
Originally posted by yojimboguy
OTOH, the "Goldfinger" painted skin thing is essentially TRUE.
Your body must sweat for temperature regulation, and having all your pores sealed could kill you.
Sorry to hijack, but this is called the Goldfinger myth in body-pianting circles, from what I've read.

A couple of quotes:

http://www.photo.net/nudes/body-paint

Quote:
Oh and the thing about not covering the whole body is not true. It is perfectly safe to do so... someone has been watching too much James Bond (Goldfinger!) In the world of fetish some people clad themselves entirely in rubber with nothing but a small straw sticking out of their mouths to breathe, all that happens is they sweat a lot. Most make-up is breathable to a certain extent, although if it is very thick a model may sweat. Dri Clor or a really powerful anti-perspirant applied first will do the trick, follwed by a good dose of spray sealant once you are finished.
http://www.bodypaintart.com/Body_Pai...Technique.html

Quote:
Finally, I want to address the "Goldfinger" myth, for those people who get their medical information from the movies.

People breathe through their lungs, not their skin. Total coverage of a person's body with paint will not suffocate them. I'm speaking from personal experience here, so anyone who disagrees should send me some medical references or citations that demonstrate otherwise.
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  #12  
Old 07-28-2002, 08:30 PM
Boyo Jim Boyo Jim is offline
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Snopes supports my statement. It has nothing to do with "breathing" or air supply, it's about body temperature regulation.

Do a search in Snopes using "Goldfinger". Painting your entire body could indeed result in your death.
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  #13  
Old 07-28-2002, 09:30 PM
Muffin Muffin is online now
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Quote:
Originally posted by Gut
I only fell through the edge of a cloud and still felt little stingy bits on my face. I bet going through the centre of a cloud or actual rain really stings.
Once one is through the cloud and falling along with the rain, hail, and frogs, what is the speed one falls at, and what is the speed the rain falls at?
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Old 07-28-2002, 09:49 PM
Gut Gut is offline
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Quote:
Originally posted by Muffin


Once one is through the cloud and falling along with the rain, hail, and frogs, what is the speed one falls at, and what is the speed the rain falls at?
Terminal velocity for a person is about 120mph in a stable position. i.e. the tummy down, arms and legs spread out. I think it's about 180-200mph if you dive.

Rain varies greatly as explained here. I'm not feeling particularly math capable right now so I can't do the m/s to mph conversion for you.

I don't know about frogs and hail.

As an aside the cloud I fell through the edge of looked nice and soft and fluffy from above. It was a beautifull day with just a few of those puffy clouds floating around. They aren't so fluffy as they would have you believe.
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  #15  
Old 07-28-2002, 11:13 PM
Jet Jaguar Jet Jaguar is offline
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Quote:
Originally posted by yojimboguy
I have real trouble believing that National Geographic would put out such crap. Are you sure that's where you saw it, and not a "factoid" piece produced by some idiot, and aired by the station alongside the NG show?
It was definitely National Geographic Explorer, on MSNBC. Here's a link to the episode in question, though they don't mention this factoid on the page (it's just an episode summary, really). The bumper was presumably produced by them, as it was narrated by the same guy that narrates the show (I forget his name), the visual and audio styles blended together in a way that looks like they were produced together, and it was the usual type of question-answer bumper they use to keep you through the commercial break.
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  #16  
Old 07-29-2002, 07:23 AM
Muffin Muffin is online now
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Quote:
Originally posted by Gut


Terminal velocity for a person is about 120mph in a stable position. i.e. the tummy down, arms and legs spread out. I think it's about 180-200mph if you dive.

Rain varies greatly as explained here. I'm not feeling particularly math capable right now so I can't do the m/s to mph conversion for you.
Thanks for the link. 120 mph is 53.65 meters per second.
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  #17  
Old 07-29-2002, 07:36 AM
Philster Philster is offline
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What altitude does a typical dive start at? Just curious.
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  #18  
Old 07-29-2002, 07:58 AM
Ringo Ringo is offline
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Altitude - IIRC static line jumps were from ~2000-2500 feet and freefall was from ~12,000 feet. YMMV.
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  #19  
Old 07-29-2002, 08:39 AM
scotth scotth is offline
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Yep, if National Geographic said that stuff, they are full of it.

1) I've done many jumps with freefall over 60 seconds. That is a pretty long time to hold your breath. Many people could do that, but it would be a long time for many others. I never had any problems breathing while in freefall. Some people report a bit of their breath catching in their throat from the high speed wind, but they get used to it after a few jumps usually. Many people have experienced this as kids sticking their head out the car window. If you stay out there, you figure out how to breath just fine.

2) You are not supposed to "punch clouds" while skydiving. It is a safety issue, as you cannot see hazards (like aircraft) below you. It is pretty easy to avoid collisions (even during freefall) if you know something is below you. All that said, most everyone has punched a cloud sometime or another. It doesn't hurt, or affect your breathing, it is just humid and moist feeling.

3) I have hit some rain in freefall. Not very pleasent, but not dangerous either. I did it jumping in shorts, t-shirt and sandals. (Which is how I liked to jump anyway) Plenty of stinging on the face, arms and legs, but no damage.

4) 120 mph is at the high end of what people fall at in a stable position. 110-115 is more typical. I am pretty lanky and tend to fall at about 108mph. (One of the reasons I like to jump in shorts and t-shirt, I fall a bit faster and can "stay down" with other jumpers more easily.) Going into a head or feet down position (which takes a good bit of practice to stay balanced in, kind of like riding a bike or unicycle for example) will easily take your speed to above 200mph. One note, be sure to get back to belly down long enough before deploying your parachute to get your speed back down to a more normal speed. Opening a parachute above 135 mph or so can be pretty unpleasent if not dangerous.

5) As to oxygen, it is very common to jump from up to 15,000 without any type of supplemental oxygen. The planes that you past say 12,500 feet are usually pretty high performance and get you that last 2 or 3k feet pretty quick, so there isn't really any issues with hypoxia. Going to 18k feet, it is usually a good idea to be on oxygen during the plane ride. That will keep the blood oxygen level high. You remove the oxygen shortly before you jump. You will have plenty of oxygen in the blood to get you safely to a lower altitude during freefall. This technique of wearing oxygen in the plane works well to about 23k feet. At 23k feet a person has about 4 minutes of unimpaired conciousness. You can safely take the mask off a full minute before actually jumping, fall for 50 or so seconds and be back below 15k with no problems. The highest jump I have personally made is from 18.5k feet.
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  #20  
Old 07-29-2002, 06:07 PM
Muffin Muffin is online now
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Thanks for the informative post, Scotth.
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