Red Bull's Mach 1 Skydive

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Plenty of breathless ink and commentary has been focused on the Red Bull Stratos jump this week, but it occurred to me that the biggest survival challenge isn't flight above the Armstrong line or delicate balloon plastic, but frustration. I was watching the Red Bull live feed when they scrubbed the attempt today. The disappointment was palpable, even through the video link. It's not clear if it will be rescheduled for Wednesday or not.

The difficulty in pulling off such a jump—and the balloon flight itself—is so enormous that windows of opportunity come fleetingly and they have to coincide with all the equipment working right when the window cracks open. Joe Kittinger, who's the capcom on Felix Baumgartner's Stratos jump, knows all about this. He is, of course, the current record holder for the highest parachute jump; 102,800 feet during Project Excelsior III on August 16th, 1960. Looking back on the details of that jump, you can only conclude Kittinger has a pair. I'm surprised he survived.

Excelsior was real science and intended to prove that military pilots could eject at high altitude and expect to survive protected by the standard-issue partial pressure suit that was cutting edge in 1960. And that's exactly what Kittinger jumped in. Fifty two years after the fact, it seems insane. Baumgartner's attempt has its risks, but his life support system is far more sophisticated and reliable than anything the military could dream up in 1960. Kittinger has been quoted as saying Baumgartner's suit—built by David Clark—is or at least points the way to the next generation space suit.

Whether that's true or not, Stratos is not the sort of science Excelsior was, but it is Ninja-level marketing by Red Bull, who excels at such things. The brand exposure is priceless, but not without risk. If it goes bad, it could go really bad.

As a skydiver, I've been curious about how Baumgartner is going to pull off supersonic freefall. To understand the challenge, consider the difference between drogue fall and freefall. Drogue fall, which is what Kittinger did to avoid the potentially fatal problem of a flat spin, involves deploying a drogue of some kind. In Kittinger's case, it was an ingenious multi-stage parachute system called the Beaupre Multi-Stage Parachute. It basically deployed partially in a reefed condition, then inflated via aneroid at a pre-set deployment altitude of 18,000 feet. That is, by the way, an unusually high deployment altitude. True airspeed in freefall is still quite high so opening shock would be an attention getter. Kittinger deployed high perhaps because he needed time to reconfigure himself for landing, including unfastening a heavy instrument package. Baumgartner will deploy at 5000 feet.

The BMSP put Kittinger's feet to earth in a stable mode. He could actually control his azimuth with his arms and legs. In true free fall, the standard stable mode is belly to earth, arms forward, legs back in an arch. But skydiving has evolved such that skilled skydivers can fall or fly stable head down at speeds considerably faster than belly-to-earth free fall. But to achieve head down stability requires control surface input—basically arm and leg movement—against the relative wind.

The Stratos web site seems to suggest that Baumgartner will exit and transition to head down at 120,000 feet or wherever the balloon reaches float. Or it could be he's planning on what skydivers know as tracking, arms to the side, palms down. There's not enough detail on the site to know for sure. Theoretically, the head down will allow him to reach his Mach 1 goal before reaching denser air and slowing down. (In drogue fall, Kittinger reached Mach .9.) What no one knows is if there's enough air density at that altitude for normal control inputs to be effective. Research aircraft flying at such altitudes use reaction controls to supplement or even substitute for aerodynamic control surfaces.

In his excellent book, The Pre-Astronauts, author Craig Ryan reports that the highest known freefall parachute jump was done by Soviet military jumper Major Yevgeny Andreyev in 1962, two years after Excelsior. He exited a balloon at 83,500 feet and used normal skydiving technique to remain stable without benefit of a drogue. But 120,000 feet isn't just a little higher, it's a lot higher. So no one really knows if Baumgartner will have sufficient control authority to remain head down and/or avoid a flat spin. For his last Excelsior jump, Kittinger had about 33 skydives. Not much experience by modern standards. I haven't seen Baumgartner's jump numbers, but I wouldn't be surprised if it's in the thousands.

Baumgartner may also have to contend with a shock wave, whose effects on a human body, his suit, helmet and related hardware are also unknown. Research aircraft have experienced shock-wave related control issues and Baumgartner might, too.

But they've thought of that. Wisely, too. His rig contains an optional drogue that can be deployed above Mach 1—or so whatever testing they've done seems to suggest. He's got a drogue release button on his left glove, precluding the need to pull his arms in to reach a deployment handle. In a fast flat spin, as Kittinger experienced on one of his jumps, you're a passenger slowly losing consciousness. Your hands and arms, trapped in the outer circumference of a centrifuge, might as well be back on earth. Baumgartner's rig has one last fail safe: If he encounters 3.5 Gs for more than six seconds, the drogue deploys itself.

They thought of something else, too. The dark side of Major Andreyev's record freefall was that there was another jumper aboard the balloon, Col. Peter Dolgov, who rode the balloon to 93,000 feet before exiting. For reasons unknown, his parachute deployed immediately and he was either killed by the opening shock, froze to death or ran out of oxygen. If Baumgartner's reserve gets out inadvertently or otherwise fouls something, he can cut it away. That's a novel idea. A typical sport rig doesn't have that option.

A skydiving friend of mine who did some liaison work with the FAA for Stratos, says he's never seen a more prepared or professional operation than this attempt. Everything they could think of, he says, they have. But I'm sure Kittinger would be the first to say it only takes the one thing you didn't think of to crater the best of plans.

Sobering thought. Here's a tip of the helmet visor to Baumgartner and the Red Bull team. Best wishes for a safe record jump, whenever it happens.

Comments (13)

Thank heavens the Discovery Channel isn't in charge of this one.

Posted by: Richard Montague | October 10, 2012 7:56 AM    Report this comment

As much as I like to complain about our lost freedoms, he still has the freedom to attempt this. I wish them the best.

Posted by: Roy Zesch | October 10, 2012 9:18 AM    Report this comment

I enjoyed this article because it is informative and comprehensive. Thanks for the great writing, Paul.

Posted by: Neil Schmid | October 10, 2012 9:26 AM    Report this comment

Alles Gute f r den Sprung!

All the best to the team! Calm ascent, exciting "flight"/dive and a safe landing to Felix!

Thomas

Posted by: Thomas Jakits | October 10, 2012 11:53 AM    Report this comment

What is the speed of sound at 100,000 ft?

Posted by: Chuck Gross | October 10, 2012 2:38 PM    Report this comment

675.6 MPH/990 FPS At 120,000 feet, it's 696/1020

Posted by: Paul Bertorelli | October 10, 2012 2:58 PM    Report this comment

My old-pilot dad used to say "The only damn plane I'm jumping out of is one that's on fire!" Best wishes to Felix Baumgartner.

Posted by: A Richie | October 11, 2012 9:16 AM    Report this comment

Paul, thank you for such an interesting and educational article! I genuinely appreciated it.

Posted by: Gary Grubb | October 11, 2012 9:55 AM    Report this comment

Really interesting article and educational. Only thing I'm confused on is that I thought that the speed of sound at sea level was around 714 mph and decreases as altitude increases. You said the speed of sound is higher at 120k feet than it is at 100k feet. Do I have this backwards?

Posted by: Joe Sikora | October 12, 2012 11:15 PM    Report this comment

I got those numbers for this page: www.snipurl.com/25ai8y6

It's true that Mach 1 speed decreases with altitude in the troposphere, but in the stratosphere is begins to increase slightly. I'm not sure why this is, but Mach 1 increases and decreases with several altitude bands.

Posted by: Paul Bertorelli | October 14, 2012 7:11 AM    Report this comment

Speed of sound is temperature, not pressure or density dependent (square root of temperature). After the tropopause, the temperature/speed of sound stays constant until about 66,000 ft, when both rise slightly. Wikipedia may have its limits, but it's fairly accurate on this topic. http://en.wikipedia.org/wiki/Speed_of_sound#Altitude_variation_and_implications_for_atmospheric_acoustics

Posted by: Mike Zippy | October 15, 2012 12:28 PM    Report this comment

http://en.wikipedia.org/wiki/Speed_of_sound#Altitude_variation_and_implications_for_atmospheric_acoustics

Posted by: Mike Zippy | October 15, 2012 12:33 PM    Report this comment

The URL is getting dropped from my posts, but go to Wikipedia for "speed of sound," and there's a discussion of variation of speed of sound by altitude, and a mathematical derivation of why it varies with temperature, not density or pressure (Actually, it varies with pressure and density, but in such a way that one can use ideal gas law to make the relationship between those tow terms entirely dependent on temperature).

Posted by: Mike Zippy | October 15, 2012 12:36 PM    Report this comment

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