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Skydiver To Break Sound Barrier During Free-Fall 311

Posted by Soulskill
from the some-velocities-are-more-terminal-than-others dept.
Hugh Pickens writes "Over fifty years ago, American Joe Kittinger made history by leaping from a balloon at 102,800 ft, and although many have sought to repeat the feat, all have failed. Now, BBC reports that Austrian extreme sportsman Felix Baumgartner will try to break the long-standing record for the highest ever parachute jump, skydiving from a balloon sent to at least 120,000 ft, and it is likely that 35 seconds into in his long free-fall of more than five minutes, he will exceed the speed of sound — the first person to do so without the aid of a machine. 'No-one really knows what that will be like,' says Baumgartner. Although challenges in the endeavor include coping with freezing temperatures and ultra-thin air, a key objective for Baumgartner will be to try to maintain a good attitude during the descent and prevent his body from going into a spin and blacking out. 'The fact is you have a lot of different airflows coming around your body; and some parts of your body are in supersonic flow and some parts are in transonic flow. What kind of reaction that creates, I can't tell you,' adds Baumgartner."
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Skydiver To Break Sound Barrier During Free-Fall

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  • I'll bet (Score:5, Insightful)

    by Vinegar Joe (998110) on Saturday January 23, 2010 @12:05PM (#30870042)

    It's really going to hurt.

  • by pnewhook (788591) on Saturday January 23, 2010 @12:10PM (#30870078)

    So I guess I'm not the only one to think this guy is going to die doing this stunt.

    • by fuzzyfuzzyfungus (1223518) on Saturday January 23, 2010 @12:17PM (#30870130) Journal
      I suspected, and breaking slashdot rules and reading TFA confirmed, that his suit is designed to automatically deploy the parachute at some failsafe altitude, even if he blacks out earlier.

      Still plenty of room for things to go wrong, people manage to die doing perfectly ordinary parachuting from time to time; but probably more dramatic than dangerous.
      • by Anonymous Coward on Saturday January 23, 2010 @12:42PM (#30870300)

        To go that fast, he will need to be extremely streamlined. Air becomes incompressible at supersonic speeds, so either his feet or head will need to handle the friction and stress created. I'd want a stability bar running the length of my body that my feet, legs, torso, shoulders, arms and head "clip" into.

        To get out of that streamlined attitude is easy. To get out of it safely is a different matter completely. I'd want a way to release a trailing parachute, attached to my shoulders, to bleed off most of the speed. Perhaps down to 200 mph.

        Slowing from 1200+ fps to 120 fps is a big deal and without extremely careful methods to retain something call static stability http://en.wikipedia.org/wiki/Longitudinal_static_stability [wikipedia.org] and he will end up tumbling out of control, breaking limbs or worse.

        Any way, I wanna watch. I hope he does the trailing smoke thing!

        • Re: (Score:2, Insightful)

          by Mitchell314 (1576581)
          He shouldn't feel more than 1 G pushing back on him. I know I abused units, but it's no more force than the ground pushing back on you. Newton's 3rd law. Terminal velocity means acceleration of gravity = -acceleration due to resistance. Otherwise, as long as he doesn't go very far past TV, he shouldn't have to worry too much in that regard (With or without all the other problems). Friction and heat? I don't know how bad that'll be, I hope he does the math before cooking like an egg. If he does cook, that is
          • by Bruha (412869)

            More like he should be wearing a suit that gets more stiff where it tries to vibrate as the wind compresses his skin. If you've seen people in wind tunnels and watch their skin make waves, that needs to be prevented with this guy.

            More likely he's going to rip up some areas of his skin severely and it's entirely possible he'll bleed out before he gets to the surface.

          • Re: (Score:3, Interesting)

            Otherwise, as long as he doesn't go very far past TV, he shouldn't have to worry too much in that regard

            Remember, he's going to be falling for a good long time in air so thin it's pretty close to vacuum -- I'd guess that terminal velocity at 120,000 feet is a hell of a lot faster than it is down here. He'll be moving very, very fast when he gets down to the thicker parts of the atmosphere. Fast enough to cause deceleration significantly greater than 1G? Dunno, but it wouldn't surprise me.

        • Re: (Score:3, Insightful)

          by ravenspear (756059)
          Air becomes incompressible at supersonic speeds

          No it's the opposite, it becomes compressible at supersonic speeds. Low speed airflows are incompressible.
      • by Kjella (173770)

        If he's still coming down straight, that's fine. If he's in a spin, the chute can start off in any direction, it can tangle in itself or in him and never extend properly. And he definately wouldn't want to be unconscious hitting the ground, without controlling the landing that too will be nasty. Automatic releases are a last-ditch emergency resort because you certainly won't survive wihtout the chute, not something you'd want to rely on.

        • It should be noted that the current record holder *did* go into a spin, and if he had been going any faster in it would have died just from how fast he was spinning in addition to blacking out (which he did).

        • by Zocalo (252965)
          Maybe they plan on using a smaller drogue chute to try and get him the right way up first and reduce the speed of descent a little to lessen the strain on the main chute. wouldn't really matter quite so much if that tangles, as long as your design means that you can safely jettison it or otherwise get it out of the way before you deploy the main chute once things have settled down.
    • I was wondering that as well, considering that the first airplanes that exceeded the speed of sound broke apart due to the stresses.
    • by Jeremi (14640)

      So I guess I'm not the only one to think this guy is going to die doing this stunt.

      I think it's likely that he won't... he's done similarly dangerous stunts before and is still alive, so it's not like he's some clueless bozo who doesn't know what he's doing. I think he (and his support team) have analyzed the risks and believe they have a reasonable chance of success, or they wouldn't be doing it.

      I think the key piece of technology here is the altimeter that automatically opens his parachute for him. He m

    • by dimeglio (456244)

      I didn't read TFA but I would first send down a few up-aimed video cameras and a dummy. This is going to help him capture the fall and see if the dummy breaks-up when it hits the sound barrier. Kind of a dry run. If all goes well, he could then safely jump. At least, he will know the risks better. A trail of smoke thing sounds like a great idea but likely impractical.

  • Just like car racing, I want to watch.
  • Star Trek (Score:3, Interesting)

    by tripmine (1160123) on Saturday January 23, 2010 @12:11PM (#30870096)
    Am I the only one that though of the space diving scene from Star Trek 11?
  • Failed how? (Score:5, Funny)

    by Greger47 (516305) on Saturday January 23, 2010 @12:22PM (#30870168)

    American Joe Kittinger made history by leaping from a balloon at 102,800 ft, and although many have sought to repeat the feat, all have failed.

    Failed?!? How can you fail that? Throw yourself self off the balloon and miss the ground?

    /greger

  • A simple machine (Score:2, Insightful)

    by psnyder (1326089)

    he will exceed the speed of sound — the first person to do so without the aid of a machine.

    He's using a machine. It's a balloon that sends him up 120,000 ft.

    • Re: (Score:2, Insightful)

      by Anonymous Coward
      Well aren't you the Number One Wet Blanket.
    • by raddan (519638) *
      I think TFA meant without a machine to propel you on the way down. At that point, it's just you and gravity.
    • Re:A simple machine (Score:5, Interesting)

      by Anubis IV (1279820) on Saturday January 23, 2010 @01:09PM (#30870526)
      Not true at all. He wants to exceed the speed of sound by falling quickly, but the dang balloon keeps lifting him up! If anything, it's actively working against him!

      On a more serious note, which simple machines would you say make up a balloon? Is it a pulley? A wedge? A lever? A balloon is just hot air in a sack. Nothing machine-like about that, though I suppose the mechanism for generating hot air may involve a machine, but that's tangential.
      • I thought the definition of a machine was something about moving parts?

        • by jschen (1249578)
          By that definition, a passively cooled computer wouldn't be a machine.
          • by tepples (727027)
            Unless it's a netbook, it still has moving parts: hard drive and optical drive.
            • by jschen (1249578)
              Oops... forgot about the hard drive. Stick an SSD in there and pull out the (non-essential) optical drive, and you no longer have moving parts. Still clearly a machine.
    • by Sir_Lewk (967686) <sirlewk@nOSpAm.gmail.com> on Saturday January 23, 2010 @01:09PM (#30870536)

      You must be a big hit at the parties.

    • he will exceed the speed of sound — the first person to do so without the aid of a machine.

      He's using a machine. It's a balloon that sends him up 120,000 ft.

      Gah. The basic assumption here is that he's not using powered flight to get him up there ... the fact that a balloon can be considered a mechanical device is irrelevant. And even if he were using a rocket or other such machine to get him there, it would hardly detract from the feat itself, that of falling almost 28 miles. Why the summary even bothered to state that he's not using the aid of a machine is stupid anyway ... of course he's using a machine of some kind to get that far off the planet. What else w

    • Re: (Score:2, Insightful)

      by 517714 (762276)

      Whether one uses a lever, a classic machine, or a balloon to raise an object is irrelevant. The fall from it is not aided by the machine. Using your (il)logic, one could not jump off the top of a mountain without using a machine - an inclined plane.

  • by starbugs (1670420) on Saturday January 23, 2010 @12:42PM (#30870298)

    Test the survivability of this by using a dummy with G-force sensors (just like we see on Mythbusters).
    Then, if all goes well - try the stunt.

    And please, use some kind of stabilizer to make sure you don't turn into a frisbee.

    I do see potential in this 'experiment' if anyone ever needs to bail out on spaceship2.

    • by X0563511 (793323)

      On that note... I do hope he has some kind of data recording system.

      While the speed and pressures will not be the same, the data collectible may well be invaluable if someone decides to invent an ejection system that functions at mach1 or beyond.

    • OK, you've hit on the best idea right there! Get Mythbusters to test his idea first. If Buster (the dummy) survives, then out come the explosives!
  • Sound barrier (Score:3, Insightful)

    by russotto (537200) on Saturday January 23, 2010 @12:50PM (#30870362) Journal

    I'm going to guess that he doesn't break the sound barrier. The term "barrier" isn't entirely fanciful, as power required to go faster increases enormously as you approach it.

    On the other hand, if he DOES break the sound barrier, I'm going to bet it does him some injury.

    • by rossdee (243626)

      The trick is to start out high enough that you build up enough speed before hitting the dense atmosphere. The speed of sound decreases as the air gets thinner too.

      • by Meumeu (848638)

        The speed of sound decreases as the air gets thinner^Wcolder too.

        Fixed that for you.

  • by Zero__Kelvin (151819) on Saturday January 23, 2010 @01:01PM (#30870462) Homepage
    I realize that Terminal Velocity will be higher with less air density, and the speed of sound should be lower, but do they both change so much that this is actually possible?
  • by captainskyhawk (1652491) on Saturday January 23, 2010 @01:04PM (#30870488)
    Isn't "terminal velocity" lower than the speed of sound?
    • by Geoffrey.landis (926948) on Saturday January 23, 2010 @01:11PM (#30870542) Homepage
      Pretty good information about high-altitude skydiving here: Speed of a Skydiver [hypertextbook.com]
    • by WittyName (615844) on Saturday January 23, 2010 @02:00PM (#30870892)

      The speed of sound depends on the density of the air. Your acceleration would also be affected, drag is at a cube rate or fourth?!? rate. Gravity depends on the distance from the center of the earth. Without doing the math, there should be some region where resistance is low, acceleration fairly high, allowing supersonic speed.

      Some body armor, perhaps a viscous gel embedded with carbon fiber, seems wise! Maybe a helmet to keep facial features from being torn removed.. Frost burn, too.

    • Re: (Score:3, Interesting)

      by Angst Badger (8636)

      Isn't "terminal velocity" lower than the speed of sound?

      Terminal velocity depends on aerodynamic drag. At altitudes that high, there atmosphere is quite thin, so there's not much drag and a man-sized object can fall well in excess of the speed of sound. In fact, the air is so thin at 100,000 feet that even deploying his parachute wouldn't do much to slow him down. When he reaches the lower, denser parts of the atmosphere, he'll slow down considerably.

      If not, terminal velocity in the lithosphere is approximately 0 mph.

    • Terminal velocity is the speed a thing is going when the force of gravity pulling down is equal to the force of drag pushing up (0 net force = no acceleration, ie constant velocity). The force due to drag at high altitudes is very low because there's not much air that high, which means there's not much to keep gravity from accelerating the sky diver. As he descends and the air gets thicker he will decelerate back to subsonic speeds because terminal velocity is lower at lower altitudes (all else being cons

    • Re: (Score:3, Informative)

      by selven (1556643)

      The guy's starting at over 36km. Air pressure is about one 200th that of surface pressure [wolframalpha.com]. Given that the acceleration needed to counter drag increases with velocity^2 (if you're going twice as fast, twice as many air particles hit you at twice the relative velocity), that means that terminal velocity is 14 times as high as usual. Terminal velocity at the surface for a mostly vertical human with gear (I estimated 0.30m^2) is 200 m/s [wolframalpha.com], so up there the terminal velocity is over 2800 m/s, or about 9.5 times th

  • Drift? (Score:4, Interesting)

    by RevWaldo (1186281) on Saturday January 23, 2010 @01:07PM (#30870512)
    During the fall, how far could he drift from the balloon's overhead position? A few miles? Tens of miles?
  • by bobdotorg (598873) on Saturday January 23, 2010 @01:12PM (#30870558)

    If you fart while exceeding the speed of sound, will it make a noise?

  • by tomhath (637240) on Saturday January 23, 2010 @01:18PM (#30870602)
    Strictly speaking the record will be for highest parachute jump. Assuming he's alive when he jumps he should get the record, even if he lands in several pieces.
  • Braking deceleration (Score:3, Interesting)

    by Arancaytar (966377) <arancaytar.ilyaran@gmail.com> on Saturday January 23, 2010 @01:21PM (#30870620) Homepage

    Aside from the air friction, it's going to jolt like hell when his chute opens and he starts to decelerate.

    • I imagine his chute will be specialized to allow for variable resistance. This does make the jump much more dangerous, however. Even with a fail safe, his chute will likely deploy with the resistance to the minimum, so he'll come in pretty fast.

      I don't really know, I'm just guessing mostly.

  • golfer (Score:5, Funny)

    by mordorph (1342355) on Saturday January 23, 2010 @02:05PM (#30870926)
    The Difference between a bad golfer and a bad skydiver? one goes *Whack*... "D@mn". the other goes "D@mn"...Whack.
    • Re: (Score:3, Funny)

      by dangitman (862676)
      Nobody says "damn" in those situations. They say "fuck" or "shit" or "fucking cunt."
  • by DynaSoar (714234) on Saturday January 23, 2010 @08:12PM (#30873966) Journal

    Interviewer: "Is that your crash helmet?"
    Jose' Jimenez: " . . . oh I hope not."

    Using:
    standard atmosphere http://www.desktopaero.com/stdatm.html [desktopaero.com]
    Mach/altitude tables http://www.aerospaceweb.org/question/atmosphere/q0112.shtml [aerospaceweb.org]
    g acceleration http://en.wikipedia.org/wiki/Terminal_velocity [wikipedia.org]
    and historical stuff on Col Joe.
    At 35 seconds he'll have fallen from 120kft to 80kft, going 1126 ft/s. That's Mach 1 at sea level. At 80kft it's Mach 1.15, giving some room for drag error. 10 seconds later he'd cross from stratosphere to tropopause where Mach 1 is lowest, but since it's only a matter of ~6 ft/s, this just gives him room to fall farther if need be but not required. At 80kft the dynamic pressure will be around 55 lb/ft^2, so if fully loaded he weighs more than 165 lbs he'll still accelerate some, but not after the 45 second mark. If he's outfitted like Kittenger was, he'll weigh up towards 300 lbs, and would still accelerate for some time.

    At 30 seconds he'll be falling at 965 ft/s, or Mach 0.98, well within the narrow transonic region of highest pressure, "max Q". This is where aircraft prior to the Bell X-1 came apart due to the buffeting of turbulence combined with the growing bow shock pressure wave.

    He can do it theoretically. The altitude is just about perfect for the attempt. I'm more concerned about whether he'll be able to keep from getting the piss kicked out of him at the Mach line. Sure, it'll be slight compared to what General Chuck punched through, but he's a damn sight slighter than the X-1. On the other hand Kittenger hit Mach 0.96 around 60kft and I see no report of this effect so maybe it's not a problem.

    It may still be a problem to punch through though. There's a spike in the speed/drag curve that's greater or lesser depending on the drag characteristics (coefficient of drag of cD). If his outfit will be shaped to approximate a low cD body so much the better. Since he'll require some form of protection I doubt anyone would fault him for choosing a shape to fit his flight profile.

    If he kept up his falling profile he's still slow to terminal velocity for the lower altitude, around 200 MPH, slower still if he's either braking or blacked out and spinning. Lower altitude here is taken to be where he could pop the chute and stay conscious even if he lost his mask, around 20 kft. At that altitude and speed a full open would be quite a jerk, but no more than airborne troops practice, and which I'm sure he's handled previously. If he's designing his chute to be able to be opened higher/faster should he need or want to, he'll include a drogue chute with a delay before the main, to slow him gradually to safe opening speed (especially helpful if spinning).

Ma Bell is a mean mother!

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