Gallery: Skydiver Aims to Smash Record, Sound Barrier in 23-Mile Jump
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*Editor's note: On Tuesday, Oct. 9, Felix Baumgartner will [attempt the highest skydive ever](http://stag-komodo.wired.com/playbook/2012/10/red-bull-stratos-3/) when he leaps from an altitude of 23 miles. Here's a piece we wrote earlier this summer looking at the jump in detail…* Later this summer, Austrian skydiver Felix Baumgartner will ascend to 120,000 feet in a pressurized capsule and, wearing only a spacesuit, jump. As he plummets 23 miles in the highest skydive ever, Baumgartner will become the first person to break the sound barrier in free fall. That’s the plan, anyway. To even attempt this will expose him to many challenges, including the risk that water in his body could vaporize. But one challenge in particular is foremost in everyone’s mind: What happens when Baumgartner encounters the shock waves that invariably occur when something exceeds the speed of sound? No one really knows. "Until you do it, it's still an unknown," says Jonathan Clark, the medical director for [Red Bull Stratos](http://stag-komodo.wired.com/playbook/tag/red-bull-stratos/), the team assembled to help Baumgartner reach his lofty goal. *__Above__: Felix Baumgartner, stepping into the void from 71,580 feet during a test jump in March.* Photo: Jay Nemeth/Red Bull Content Pool
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More on 'Fearless' Felix:[](http://stag-komodo.wired.com/playbook/2012/10/felix-baumgartner-stratos/) [What We Can Learn from 'Fearless' Felix's Supersonic Skydive](http://stag-komodo.wired.com/playbook/2012/10/felix-baumgartner-stratos/)[](http://stag-komodo.wired.com/playbook/2012/10/red-bull-stratos-space-suit/) [What Does One Wear on a 23-Mile Skydive](http://stag-komodo.wired.com/playbook/2012/10/red-bull-stratos-space-suit/)[](http://stag-komodo.wired.com/playbook/2012/10/red-bull-stratos-balloon/) [World's Highest Skydive Requires the World's Biggest Balloon](http://stag-komodo.wired.com/playbook/2012/10/red-bull-stratos-balloon/)[](http://stag-komodo.wired.com/wiredscience/2012/10/the-physics-of-the-red-bull-stratos-jump/) [The Physics of the Red Bull Stratos Jump](http://stag-komodo.wired.com/wiredscience/2012/10/the-physics-of-the-red-bull-stratos-jump/)Baumgartner is not the first to dream of eclipsing the unofficial record Joe Kittinger, a retired Air Force colonel from Florida, set in 1960 when he jumped from 102,800 feet. Australian [Rodd Milner planned a jump](http://stag-komodo.wired.com/wired/archive/9.08/space.html) in 2001, for example, and Frenchman Michel Fournier aborted attempts at the record in 2008 and 2010. Baumgartner will jump from the stratosphere for several reasons, not the least of which is because he can. The seasoned skydiver and BASE jumper wants to set records for the highest jump and longest free fall. But there’s also some scientific inquiry in all of this, in learning what happens to the body as it approaches and breaks the sound barrier. Such data will be of interest to military and commercial aerospace, especially companies like Space X and Virgin Galactic. “I think the data gathered will be very interesting for the technical community that is concerned with the specific scenarios pilots will face if they have to bail out at supersonic speed,” says John D. Anderson, the curator for aerodynamics at the National Air and Space Museum and a professor emeritus in the department of aerospace engineering at the University of Maryland. Many people have exceeded Mach 1 and beyond in airplanes, of course, but it’s anyone’s guess what will happen when “Fearless Felix” crosses that threshold wearing only a pressurized suit. Should he succeed, “it’s going to be huge,” Clark says. *__Above__: Baumgartner during egress training earlier this year in Lancaster, California.* Photo: Jörg Mitter/Red Bull Content Pool [](http://stag-komodo.wired.com/playbook/?attachment_id=12006) *__Above__: A ground crew helps Col. Joe Kittinger remove his flight gear after jumping from 102,800 feet during the Excelsior III program at Holloman Air Force Base on August 16, 1960.* Photo: U.S. Air Force
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Baumgartner will ascend to the edge of the stratosphere in a [pressurized capsule carried aloft](http://stag-komodo.wired.com/autopia/2012/03/red-bull-capsule-ready-for-record-breaking-skydive/) by a balloon. When he reaches 120,000 feet – the highest manned flight ever in a balloon, by the way – he will step into the void. He expects to free fall for at least five minutes (another record) and exceed the speed of sound, in the vicinity of 700 mph at that altitude. A [test jump from 13 miles up](http://stag-komodo.wired.com/playbook/2012/03/red-bull-stratos/) went off without a hitch in March, and Red Bull Stratos plans another before the final jump sometime between July and September. Each successful test only increases Baumgartner's confidence in the jump, and the team helping him make it. "Every flight that has ever taken off had risks," he said. "The most important thing is to minimize the risk to an acceptable level. Of course I realize that the dangers are more extreme in this project because we are going up to a really hostile environment. And I do feel fear. But I think fear is a natural asset — it helps me stay sharp, and fighting it would only use up energy. At this point, I feel confident because we've done so many tests — each one has been more difficult, and every success has motivated us." During the development of supersonic aircraft, engineers learned the hard way that there are aerodynamic rules that must be followed if the wings and tail are to continue functioning with a shock wave. Baumgartner can expect these shock waves to begin building as he surpasses Mach 0.7. At that speed he'll enter what’s called the transonic region, and the waves probably will cause vibrations that he will feel around his helmet and shoulders. As he achieves the speed of sound, Baumgartner will encounter compression shock waves that will form just in front of his helmet and shoulders. As this happens, Anderson says, Baumgartner will feel increasing in pressure against his body, because pressure always rises behind a shock wave. *__Above__: Baumgartner and life support engineer Mike Todd check the fit of Baumgartner's pressurized suit.* Photo: Sven Hoffmann/Red Bull Content Pool
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The fact Baumgartner will be 18 to 20 miles above Roswell, New Mexico when this happens will be to his advantage. The air is very thin at that altitude and the shock waves are expected to be relatively weak compared to those experienced by aircraft at lower altitudes, where the air is denser. For this reason, the team hopes the waves will have “minimal, if any effect” on Baumgartner and his ability to maintain control. Still, he isn’t in the clear just yet. Even as he falls, he will pass through increasingly dense air, which could create a new set of problems. "Because he’ll be in thicker air when he decelerates back under the speed of sound, theoretically the transonic vibrations could be stronger than those he initially experienced," says Art Thompson, the mission's technical project director. Baumgartner will want to remain as aerodynamic as possible when he passes through the sound barrier. As soon as he steps from the capsule he’ll assume the delta position, meaning head first, arms at his side. That shape mimics that of most supersonic airplanes, keeping flight control surfaces within the shock wave cone. But what happens if Baumgartner fails to maintain this position? Should, say, his arm move beyond the cone, it would increase the drag and the effects of the shock waves. If the drag were severe enough, it could result in his arm being torn off, much like an aircraft losing a wing. “It's not something I'd want to do,” Anderson says. *__Above__: Baumgartner, testing the capsule he'll ride to 120,000 feet.* Photo: Christian Pondella/Red Bull Content Pool
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Assuming the optimal position is easier said than done at 120,000 feet. At that elevation, the air is so thin — the pounds per square inch absolute is 0.067 — it is “virtually a vacuum,” the Red Bull crew says. That makes maneuvering tricky, because Baumgartner will need air resistance to shape his body into the correct form. There are varying estimates as to how long it will take Baumgartner to assume the correct position, but Luke Aikins, the principal skydiving consultant, suspects Baumgartner could fall 20,000 feet before encountering enough resistance to start taking control of his body position. If Baumgartner can't assume the delta position or loses it mid-flight, he could go into a flat spin, which would be a problem. In a flat spin, which also can happen below the speed of sound, Baumgartner would spin uncontrollably, sending his blood rushing toward the extremities. If it rushes to his feet, he could black out. If it rushes to his head, it could cause a potentially fatal brain aneurysm. Baumgartner also faces the possibility of going into a tumble. Aikins says such a spin is more likely than a flat spin, and he suspects Baumgartner will go into a slow tumble after stepping from the capsule as the weight of his chest pack and parachute pull him over. Tumbling could send blood rushing to one end or the other. If Baumgartner does find himself in a tumble right away, Aikins says, he should have plenty of time to pull himself out of it before he starts rotating fast enough for it to become a problem. *__Above__: Baumgartner in the capsule.* Photo: Jörg Mitter/Red Bull Content Pool [](http://stag-komodo.wired.com/playbook/?attachment_id=11999) *__Above__: It's a tight fit in the capsule.* Photo: Red Bull Content Pool
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To ensure Baumgartner stays safe if he starts spinning, he will wear a device on his wrist called a “Gwiz.” Aikins says the device, which he helped design, uses accelerometers and sophisticated software to monitor the g-forces Baumgartner will experience. If the Gwiz reads a force of 3.5 g or more for six continuous seconds, a drogue, or mini, parachute will automatically deploy — even if Baumgartner is unconscious — to help stabilize him. Baumgartner can deploy the drogue manually if he feels out of control, but will have to wait at least half a minute after stepping from the capsule. Aikins says there is a 30 second delay on the drogue chute because that’s how much time is needed to experience the air resistance to properly deploy the chute. Any sooner and Baumgartner could get tangled up. "Felix won’t want to deploy the drogue if he can stabilize himself using his body position because it would slow him in his quest to reach the speed of sound," the team says. "But it’s there just in case he needs it." *__Above__: Baumgartner rode his capsule, carried aloft by a balloon, to an altitude of 71,580 feet during his first manned test in March.* Photo: Jörg Mitter/Red Bull Content Pool
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Baumgartner is set to deploy his main chute at 5,000 feet and will need to have slowed to at least 172 mph for it to work. Red Bull says that shouldn’t be a problem. A reserve chute will deploy if a sensor detects that Baumgartner is exceeding 80 mph when he passes below 1,500 feet. The entire jump should take a little more than 15 minutes, with five and a half minutes of free-fall and 10 minutes with his chute deployed. Kittinger was an Air Force colonel when he set the unofficial record by jumping from 102,800 feet (19.5 miles) in 1960. Kittinger, 83, is a mentor to Baumgartner and among his chief advisers, along with a former NASA flight director and an engineer who worked on the B-2 bomber. Russian cosmonaut Yevgeny Andreyev set the official record for a high-altitude jump without a stabilizing drogue chute when he leaped from 83,500 feet in 1962. Four years later, Lockheed test pilot Bill Weaver was thrown from his SR-71 Blackbird when it broke apart at 79,000 feet while traveling at MACH 3.18, or more than 2,100 mph. Although he lived to tell the tale, nothing about his fall was actively monitored to understand what he experienced. That’s a gap in our knowledge that Baumgartner and his team hope to fill. *__Above__: Baumgartner, about to step into the void from 13 miles up.* Photo: Red Bull Content Pool [](http://stag-komodo.wired.com/playbook/?attachment_id=11997)
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*__Above__: Baumgartner celebrates completing his jump from 71,580 feet above Roswell, New Mexico, in March. He plans another test jump before making his leap from 120,000 feet later this summer.* Photo: Christian Pondella/Red Bull Content Pool
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