Up, up and away ... oh shit, wait, wait!
December 21, 2011 9:24 AM   Subscribe

Comic-book physics question: Let's say I'm a superhero whose only power is the power of flight. How fast could I fly in the atmosphere before I get injured, ripped apart or burned up?

At some point, you'd just rip your arms off, right? And if not, eventually you'd just burn up like a re-entering spacecraft.

Let's make some stipulations for the discussion.

* There's no max speed. I can fly as fast as I want, and it's up to me to determine what's safe through some trial and error and experimentation. I have some kind of magic speedometer or airspeed indicator so I'll just know what the speed is at any given moment.
* Let's say we're only testing flat out, level flight speed, with a gradual acceleration from zero. In our test, there will be no concerns about braking, turning or G-forces (other than straight-ahead flying).
* It's a magical power of flight. No rocket thrust or flapping wings. Up, up and away!
* I have no superhero-style invulnerability, magic protection or force fields.
* I'll take normal, everyday precautions available to skydivers or motorcycle riders (e.g. wearing leathers, eye-goggles and/or a full-face helmet). Let's also presume that I don't hit anything.
* Max altitude would be 10,000 feet, staying well clear of altitudes where a lack of oxygen would be an issue.
posted by Cool Papa Bell to Grab Bag (43 answers total) 11 users marked this as a favorite
 
Well, if you're going by blast or wind force then the CDC says 294 MPH.
posted by Burhanistan at 9:27 AM on December 21, 2011


Well, maybe between that and 502 MPH, depending on your helmet.
posted by Burhanistan at 9:27 AM on December 21, 2011


That depends- is your costume made of unstable molecules?

On a more serious note- 10,000 feet up and exposed is COLD. How fast could someone fly at that altitude before hypothermia becomes an issue?
posted by mkultra at 9:32 AM on December 21, 2011


It's a magical power of flight.

Then wouldn't you have a magical invulnerability to the negative effects of flight?
posted by Brandon Blatcher at 9:33 AM on December 21, 2011


Lack of superstrength would preclude you from using an Iron Man-like suit without its own propulsion as a safety device, but you could still wear something like an astronaut suit, right?
posted by elizardbits at 9:36 AM on December 21, 2011


Then wouldn't you have a magical invulnerability to the negative effects of flight?

Because that's not the question, doofus.

Lack of superstrength would preclude you from using an Iron Man-like suit without its own propulsion as a safety device, but you could still wear something like an astronaut suit, right?

Sure, but my character is an everyday kind of person that doesn't have access to high-tech materials.
posted by Cool Papa Bell at 9:38 AM on December 21, 2011 [3 favorites]


untethered EVA suits aren't especially aerodynamic anyway - your plss would rip off at high speeds and no one likes integrity breaches.
posted by elizardbits at 9:43 AM on December 21, 2011 [1 favorite]


Well, if you're going by blast or wind force then the CDC says 294 MPH.

That's going to depend on air pressure as well, I think. A thinner atmosphere isn't going to generate as much friction.
posted by empath at 9:47 AM on December 21, 2011


mkultra: "On a more serious note- 10,000 feet up and exposed is COLD. How fast could someone fly at that altitude before hypothermia becomes an issue?"

So how fast would he have to fly at 10,000ft in order to create just enough friction with the air up there to counteract the chilly temperatures?
posted by Grither at 9:52 AM on December 21, 2011 [1 favorite]


He could line his suit with hand warmers. The main issue is how much force his body could withstand.
posted by Burhanistan at 9:54 AM on December 21, 2011


Just FYI: I imagine your character will work up a pretty good oxygen saturation level if they are flying around all the time. Oxygen doesn't get really thin until more around 19,000-20,000ft. Up to 14,000 will be no problem whatsoever. Skydivers exit at 14,500 for instance.
My information is more based on different altitudes I've done mountaineering at though.

Keeping with the skydiving theme, I found this and found it interesting:

This successful 102,800 foot Air Force test jump was made, from a special high altitude balloon, on August 16, 1960 by Capt. Joseph Kittenger. He was in freefall** for nearly five minutes.

Because of the extreme altitudes involved, Joe had to wear an astronaut-style pressure-suit. Keep in mind: the world's first human astronaut, Yuri Gargarin, had not yet flown into space. Only military test pilots had exceeded 100,000 feet of altitude in experimental rocket aircraft. Joe was making a parachute jump from the edge of space. Also, at those altitudes the air was so thin, and the resultant aerodynamic drag so small, that Joe approached the speed of sound in freefall (he was clocked at around 614mph -- there is some debate that he might have even surpassed the speed of sound. But I don't think the data supports that claim).


That makes me think that it would be possible to fly quite high in even very low-tech gear.

"On a more serious note- 10,000 feet up and exposed is COLD. How fast could someone fly at that altitude before hypothermia becomes an issue?"
Just being at 10,000ft doesn't automatically make it freezing. I've been comfortably naked, outside, at 15,000ft in the sun.
posted by zephyr_words at 9:59 AM on December 21, 2011 [1 favorite]


Well, if you're going by blast or wind force then the CDC says 294 MPH.

That paper seems to be concerned with blasts, not sustained speeds you build up to, or wind that you're exposed to just out in the world. For example, it says 102 mph = serious injuries are common. I'm sure a 102 mph blast, or walking in a hurricane, would knock people off their feet and fuck them up real good. But clearly, one can ride a motorcycle that fast without harm.
posted by Cool Papa Bell at 10:00 AM on December 21, 2011


Because that's not the question, doofus.

Your origin story is important, just sayin'.

Anyway, I don't think you could find out, because you'd black out from gforces first. Assuming you've got a helmet on and a learther flight suit of some sort, you could probably handle 4-10gs, then pass out and fall to your death.

But a real problem would come from vibration, especially if you start vibrating at the same resonance frequency as internal organs. Even at low gs, that would tear you apart.
posted by Brandon Blatcher at 10:01 AM on December 21, 2011


Brandon Blatcher: "Anyway, I don't think you could find out, because you'd black out from gforces first. Assuming you've got a helmet on and a learther flight suit of some sort, you could probably handle 4-10gs, then pass out and fall to your death."

One can theoretically accelerate to near the speed of light without surpassing 1g.

Just sayin'.
posted by Grither at 10:05 AM on December 21, 2011 [3 favorites]




you could probably handle 4-10gs, then pass out and fall to your death.

Not sure about that. There are several "everyday" examples here that would indicate otherwise. For example, "Top Fuel drag racing" at 4.2 g. Those cars top out at 250-280 mph.
posted by Cool Papa Bell at 10:13 AM on December 21, 2011


Sure, I'm guessing on the Gforce numbers. I guess the question is howlong are going to be at that 4.2g or whatever and how fast are you getting there? Is it a gradual and swift acceleration?

Most people would probably try to go as fast as they can.
posted by Brandon Blatcher at 10:20 AM on December 21, 2011


You can go pretty fast without dying from G forces. Otherwise we wouldn't have a space program.
posted by Jairus at 10:22 AM on December 21, 2011 [1 favorite]


then pass out and fall to your death.
Well that depends on how the magic works, doesn't it.
posted by shothotbot at 10:28 AM on December 21, 2011 [1 favorite]


Back when I was doing some pick-up writing for Ape Entertainment, they were putting out a comic that really thought an awful lot about this stuff. It's protagonist was a regular joe with just-flight powers. I can't remember what the upshot of it was in terms of limitations, but I'll e-mail Skipper and let him know about this thread. Odds are good he's done his share of research on it.
posted by Shepherd at 10:29 AM on December 21, 2011 [1 favorite]


G-force and velocity are really two separate things. The only question here (which I'm also curious to know) is how much blast/wind force a man flying relatively unprotected in the lower atmosphere could take before his body ripped apart.
posted by Burhanistan at 10:29 AM on December 21, 2011 [3 favorites]


You can go pretty fast without dying from G forces. Otherwise we wouldn't have a space program.

Yes, it's entirely possible to fly fast in a metal enclosure and not die from G forces. One does pass out after a certain load, though, which could be a problem if you don't have that nice ship around you.

Acceleration That Would Kill a Human is interesting reading.

Presumably one would slow down if flying fast was beginning to hurt.
posted by Brandon Blatcher at 10:45 AM on December 21, 2011


You're trying to find out how much Ram Pressure a human can withstand. Is that the question?
posted by vacapinta at 10:46 AM on December 21, 2011 [2 favorites]


To add to conversation, though really not answer the question. I believe the SR71 was built to be loose until it was at its cruising altitude where it would extend, from the heat caused by its friction with air, around 20 inches (if I remember correctly)
posted by zombieApoc at 10:47 AM on December 21, 2011


Brandon Blatcher, I think you're mistaking acceleration for velocity. Cool Papa Bell can accelerate as slowly as he wants, say .1 m/s^2, and still reach any velocity he wants. It's not a G-force thing.
posted by monkeymadness at 10:52 AM on December 21, 2011 [1 favorite]


Am I crazy for thinking you'd hit a limiting speed at which you could no longer breathe before you'd hit one where you'd burn up?
posted by solotoro at 11:08 AM on December 21, 2011


Cool Papa Bell can accelerate as slowly as he wants

I doubt anyone who can magically fly is going to be accelerating slowly.
posted by Brandon Blatcher at 11:09 AM on December 21, 2011


I've been in 100 knot winds, and it's pretty uncomfortable but you can weather it with goggles and a facemask. I assume your magical power doesn't preclude you getting those things. However, on land, those same winds would carry objects up to the size of medium trees along with it and if one of *those* hits you you have some serious problems.
posted by zomg at 11:09 AM on December 21, 2011


Hey everyone. I'm the creator / writer of the book Shepherd spoke about "Bizarre New World." I did in fact spend a lot of timing dealing with this subject, but my book didn't have to deal with this precise problem you speak of.

My book is about an ordinary overweight schmoe who one day inexplicably discovers he can defy gravity, but it was important to me that I keep the tale as realistic as possible, hopefully keeping the book as relatable as possible. One way I did that was keeping his ability extremely limited. He only has enough raw power to lift his body weight and push it through the air about 15 mph. Superman he's not. Otherwise he's completely human in every way, thereby making him VERY vulnerable to the elements. Going up is one thing, but coming down gets a bit of help from gravity and momentum. A skydiving instructor helped me with the logistics. I always intended him to only fly at slow speeds, but adding gravity into the mix changed all that. My guy ends up using a wingsuit to better control his ability. Since I never have my character go at the speeds you spoke of, this never became something I needed to deal with.

Ultimately I wanted to keep his abilities reasonable because by the end of the first series it's revealed he's really only the first to get the ability and suddenly the entire human race leaps into the sky with him. I wanted to truly explore how human flight would affect the human race, and I hired a bunch of creative teams to help flesh the world out (separate from my core book) in short stories from all walks of life.

Of course there's always room for new ways to look at this subject. Raven Gregory's "Fly" is a much darker (and VERY different) approach to the concept. His book really skirts the line between ordinary people and super-humans. I tried to keep my people as ordinary as possible.

If you have any other questions I'll do what I can answer them. And good luck!

Skipper Martin
www.bizarrenewworld.com
posted by skipper_martin at 11:10 AM on December 21, 2011 [10 favorites]


You don't have to be going very fast to get a bug in your eye and lose control.
posted by Confess, Fletch at 11:12 AM on December 21, 2011


About breathing and bugs in eyes: He mentions a helmet, which would both block bugs and create an air pocket. It's conceivable that at some speed the air pocket could be too thin to breathe, but none of this is the question.

I doubt anyone who can magically fly is going to be accelerating slowly.

Unless he knows it would kill him if he didn't.

I have no data, but I think with an aerodynamic helmet (Rocketeer) and a suit that's something better than street clothes, he could go pretty damn fast, and the issues would probably become, first, losing control when he twitches a finger and starting to tumble, breaking or tearing off his limbs with the rotational G's, and two, assuming he's got that kind of control, at what point the wind/friction would rip his suit and therefore likely his skin off. I'm not sure how to go about calculating that, or if the wind shear tolerances of skin and leather have been figured.
posted by cmoj at 11:21 AM on December 21, 2011


I think breathing would become challenging pretty quickly. To inhale, you'd probably have to tilt your head to have ram air fill up your lungs, then tilt it another way so your nostrils are in a low pressure area and you can exhale. (There is an urban legend about skydivers moving quickly enough to "breathe through their skin" but it appears to be BS.)

The SR-71 aircraft flew at around Mach 3 at very high altitude and the outside of it reached what would be a deadly temperature of over 300 °C (572 °F). Plus the heating effect would be much higher at lower altitudes, so the person would have to fly very much slower than Mach 3.

BTW regarding the acceleration derail (the question was about how fast a person could go, not whether they could exercise enough restraint to avoid crushing g-force), it would take less than a minute at 2 g acceleration to reach 2000 mph, which is pretty close to Mach 3.
posted by exogenous at 11:23 AM on December 21, 2011 [1 favorite]


I doubt anyone who can magically fly is going to be accelerating slowly.

Magical flight is the only stated super power. That means our protagonist does not have the additional super power of quick acceleration.
posted by The World Famous at 11:43 AM on December 21, 2011


Using vacapinta's link for ram pressure, we have P = ρv2, where

P = ram pressure
ρ = fluid density. The atmosphere is about ρ = 0.4135 kg/m3 at 10,000 feet

Let's guesstimate an upper bound of P that a human can withstand by using the world deadlift record of 460 kgf = 4508 kg * m/s2. Suppose your area in the direction of force is about 1/4 m2, and distribute pressure evenly, for P = 18032 kg m3/ s2. Divide by ρ and we have v2 = 43608 m2/s2, so v = 209 m/s
= 467 miles per hour.

So 467 miles per hour at 10,000 feet altitude would be sort of like sustaining the world record deadlift. I doubt anybody would survive that for very long.
posted by qxntpqbbbqxl at 11:49 AM on December 21, 2011


I should add that good aerodynamics could improve that figure well past the speed of sound.
posted by qxntpqbbbqxl at 11:56 AM on December 21, 2011


qxntpqbbbqxl, going from this I figure the frontal area in the traditional Superman position to be just under half your figure, at 0.11 square meters, which all else being the same gives 660 mph if Wolfram and I did the math correctly.
posted by exogenous at 12:03 PM on December 21, 2011


I figure the frontal area in the traditional Superman position to be just under half your figure, at 0.11 square meters, which all else being the same gives 660 mph if Wolfram and I did the math correctly.

But with normal human strength, holding steady in that position at that speed is going to be virtually impossible, and when an arm comes loose or our hero's head catches the wind and snaps backwards, things are going to go all sorts of wrong.
posted by The World Famous at 12:09 PM on December 21, 2011


Straight Dope had a similar question before. There is also this previous AskMeFi thread on the force required to tear off a limb. There is probably no hard fast answer because there are a lot of variables (what position is the guy in while flying, how muscular he is, what is he wearing, does he have an oxygen supply, etc). Per the Straight Dope piece, the guy is going to suffer nasty trauma to his mouth, nose and eyes at 500 mph if he doesn't have some kind of face shield. At Mach 2, the Concord's skin temperature was 250 F and the flying man is probably not as aerodynamic. The flying man could probably negate a lot of these effects by tooling around in something like a deep sea hard suit with internal cooling. But, as the Straight Dope piece mentions, at Mach 20, even an enclosed space suit wouldn't protect him.
posted by chrisulonic at 12:15 PM on December 21, 2011


I was thinking arms at the side, but yeah if the head starts to drift and catch the wind it could get pretty ugly.
posted by exogenous at 12:17 PM on December 21, 2011


"Stable freefly head down position has a terminal speed around 240-290 km/h (around 150-180 mph). Further minimizing body drag and streamlining the body position allows to reach higher speeds in vicinity of 480 km/h (300 mph)."

World record appears to be 526 km/h (326 mph).

You can see the type of equipment they use here.

So I think you could put down 326 or mph or so as a minimum achievable speed for your superguy.

I realize that there is already a far higher speed reported above for Joseph Kettinger, but he was at a far higher altitude and also in a more substantial suit. The 326 mph figure seems to be close to the fastest speed a human can achieve in freefall close enough to the surface of the earth to actually breathe, etc. That may not the maximum figure you're looking for but it does seem to set a minimum on the speed your looking for.
posted by flug at 12:43 PM on December 21, 2011 [1 favorite]


John Strapp flew at 570 mph with no ill effects.

That's a quite different situation, as it was within an aircraft with the canopy removed. Without knowing the exact configuration of the amount of windscreen left, etc, it is hard to extrapolate, and this might be far different than being completely exposed to the airstream.
posted by flug at 12:48 PM on December 21, 2011


The fact that you asked this question makes me think you would like the book Packing for Mars, which does contain some discussion of the effects of high wind speed on humans (but which, sadly, I don't remember specifically enough to contribute content to this question.)
posted by rosa at 2:11 PM on December 21, 2011


Packing for Mars is great, but a lot of the trauma mentioned concerns the Columbia Shuttle disaster, jets breaking apart or similar accident type stuff. Fascinating yes, but wildly different from the OPs stated premise of flying straight.

The only thing that's remotely similar is several skydiving experiments from balloons at enormous heights. However, the book doesn't mention any tests with cadavers from those heights (which would be interesting), only dummies.

I would suggest that the OP experiment on other people first (I would certainly volunteer), taking them up to 10,000 feet and then dropping from there and seeing what happens.

However, since the rigidly defined comic book premise does not include super strength, which would surely be needed to carry another human being up to 10,000 feet, perhaps this a foolish suggestion.
posted by Brandon Blatcher at 6:02 AM on December 22, 2011


« Older Is Textmate for me?   |   what full-time jobs, other than retail, can i find... Newer »
This thread is closed to new comments.