# World record sky dive (today)...why was his freefall time less than the previous record? **URL:** \ **Category:** Factual Questions\ **Created:** [October 15, 2012, 1:59am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740 "2012-10-15T01:59:32Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [October 16, 2012, 1:58am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/21 "2012-10-16T01:58:35Z")
23 miles up, gravity is just as strong as at ground level. You don’t hit atmosphere, it’s a gradual thickening as you go down. He’s not going fast enough to heat up from friction. The only reason it seem re-entry vehicles “hit” atmosphere is that they’re going around 15-20,000 mph and go through the upper atmosphere in a few seconds. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [October 16, 2012, 1:58am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/22 "2012-10-16T01:58:39Z")
It’s a pretty near-vacuum at 100,000 feet. He had an additional 28,000 feet or so in a near-vacuum to build up a lot of extra speed. ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [October 16, 2012, 2:01am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/23 "2012-10-16T02:01:52Z")
> [@Dr.Colossus](#): > > what even. in that case, jumping should cause you to fall “up,” no? No. Not even remotely. Gravity is not caused by air pressure. Air pressure is caused by gravity, but just above the atmosphere there is almost as much gravity as there is on the ground. > [@](#): > > wouldn’t you need even MORE propulsion in a “near vacuum” to fly through it? (\*i say that because gravity wouldn’t be so strongly affecting you) No, again not at all. Gravity is not caused by air. When he stepped out of the platform he was in a gravity field nearly as strong as someone standing on the ground. That caused him to accelerate just as fast as he would as if he fell at sea level. The near-total lack of air around him meant he didn’t have much drag as he would if falling at lower altitude, so he reached a higher speed. > [@](#): > > i thought his high speed of falling was due to the longer distance to build up speed, not the vacuum causing less drag–i mean, that drag would cause re-entry level burn-friction when he hit atmosphere, would it not? thus burning him up/slowing him way the fuck down? He never got fast enough to be in any danger of burning up. Reentering satellites and space shuttles are hitting the air at orbital speed, which is 15000MPH or more. He was only going at about 800MPH or so, which wasn’t fast enough to cause much heating. It still probably wouldn’t have been fun if he hadn’t wearing that suit. ---
**Author:** ![Dr.Colossus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.colossus/32/9423_2.png) [@Dr.Colossus](https://boards.straightdope.com/u/Dr.Colossus)\ **Post date:** [October 16, 2012, 2:25am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/24 "2012-10-16T02:25:41Z")
cool stuff. so he slowed to terminal velocity closer to the ground? ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [October 16, 2012, 2:53am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/25 "2012-10-16T02:53:35Z")
> [@Dr.Colossus](#): > > what even. in that case, jumping should cause you to fall “up,” no? > > wouldn’t you need even MORE propulsion in a “near vacuum” to fly through it? (\*i say that because gravity wouldn’t be so strongly affecting you) > > (bear with me. i really am this stupid). > i thought his high speed of falling was due to the longer distance to build up speed, not the vacuum causing less drag–i mean, that drag would cause re-entry level burn-friction when he hit atmosphere, would it not? thus burning him up/slowing him way the fuck down? To expand on what others have said: Before he jumped from the capsule he was experiencing ~1G just like on the Earth’s surface. This may be hard to wrap your mind around but the ‘zero-G’ experienced by Shuttle & ISS occupants (or anyone in low-Earth orbit) is actually kind of an illusion. They’re essentially in (a constant) free fall. It’s the exact same thing as the so-called ‘zero-G simulating’ Vomit Comet aircraft experiences. If the Shuttle were capable of stopping its forward orbital velocity without losing altitude (magic, anti-gravity drive) then everyone & everything in it would suddenly fall to the floor of the ship and experience (nearly) 1G just like on Earth’s surface. The only humans who have experienced true zero-G (or close to it) by actually leaving the majority of Earth’s gravitational field were the Apollo astronauts who left low-Earth orbit. Sort of. Actually, again, on the way to the Moon they were still in free fall only in a much, much wider orbit. I guess if one of the missions had done a direct abort, firing the C/S module’s main engine to essentially ‘stop’ somewhere mid-way from the Earth to the Moon, turning around, and heading back to Earth, while stopped they’d have been in the closest thing to zero-G (though they’d still be in free fall orbiting the Sun). My head hurts… ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [October 16, 2012, 3:04am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/26 "2012-10-16T03:04:18Z")
> [@Dr.Colossus](#): > > cool stuff. so he slowed to terminal velocity closer to the ground? I’m guessing he pulled the chute a long time before he slowed down to standard terminal velocity. His Parachute was designed for high speed opening. Anyone seen a website with detailed charts on his speed over time throughout the descent? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 16, 2012, 3:04am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/27 "2012-10-16T03:04:44Z")
> [@](#): > > cool stuff. so he slowed to terminal velocity closer to the ground? “Terminal velocity” is not one single speed. It depends on the local atmospheric conditions. For a human near sea level, it’s only one or two hundred MPH. But in the thin air that high up, it’s much, much higher. He was probably going at very close to (local) terminal velocity for almost the entire jump, and he was never going more than slightly faster. ---
**Author:** ![Dr.Colossus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.colossus/32/9423_2.png) [@Dr.Colossus](https://boards.straightdope.com/u/Dr.Colossus)\ **Post date:** [October 16, 2012, 4:00am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/28 "2012-10-16T04:00:54Z")
> [@Chronos](#): > > “Terminal velocity” is not one single speed. It depends on the local atmospheric conditions. For a human near sea level, it’s only one or two hundred MPH. But in the thin air that high up, it’s much, much higher. He was probably going at very close to (local) terminal velocity for almost the entire jump, and he was never going more than slightly faster. would this cause stresses on a human body that might cause one to black out? it just seems like a little much, to me. i suppose that’s where the suit comes in, but fuck, that’s a fast pace for a body to fall. ---
**Author:** ![Dr.Colossus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.colossus/32/9423_2.png) [@Dr.Colossus](https://boards.straightdope.com/u/Dr.Colossus)\ **Post date:** [October 16, 2012, 4:20am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/29 "2012-10-16T04:20:17Z")
> [@Hail\_Ants](#): > > To expand on what others have said: Before he jumped from the capsule he was experiencing ~1G just like on the Earth’s surface. This may be hard to wrap your mind around but the ‘zero-G’ experienced by Shuttle & ISS occupants (or anyone in low-Earth orbit) is actually kind of an illusion. They’re essentially in (a constant) free fall. It’s the exact same thing as the so-called ‘zero-G simulating’ Vomit Comet aircraft experiences. If the Shuttle were capable of stopping its forward orbital velocity without losing altitude (magic, anti-gravity drive) then everyone & everything in it would suddenly fall to the floor of the ship and experience (nearly) 1G just like on Earth’s surface. > > The only humans who have experienced true zero-G (or close to it) by actually leaving the majority of Earth’s gravitational field were the Apollo astronauts who left low-Earth orbit. Sort of. Actually, again, on the way to the Moon they were still in free fall only in a much, much wider orbit. I guess if one of the missions had done a direct abort, firing the C/S module’s main engine to essentially ‘stop’ somewhere mid-way from the Earth to the Moon, turning around, and heading back to Earth, while stopped they’d have been in the closest thing to zero-G (though they’d still be in free fall orbiting the Sun). My head hurts… holy hell. i stopped reading mid-way and did some calculus just to settle my mind down. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [October 16, 2012, 4:47am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/30 "2012-10-16T04:47:32Z")
> [@Dr.Colossus](#): > > would this cause stresses on a human body that might cause one to black out? it just seems like a little much, to me. > > i suppose that’s where the suit comes in, but fuck, that’s a fast pace for a body to fall. Apart from when he was spinning, there are no forces on his body that he wouldn’t feel on a normal skydive. ---
**Author:** ![Pitchmeister](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pitchmeister/32/3459_2.png) [@Pitchmeister](https://boards.straightdope.com/u/Pitchmeister)\ **Post date:** [October 16, 2012, 8:49am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/31 "2012-10-16T08:49:07Z")
> [@Dr.Colossus](#): > > would this cause stresses on a human body that might cause one to black out? it just seems like a little much, to me. > > i suppose that’s where the suit comes in, but fuck, that’s a fast pace for a body to fall. And as for speed, humans experience more speed onboard a Concorde, let alone military jets. As Richard Pearse points out, the spinning (=sudden changes in acceleration) causes the problem. You can experience this on a rollercoaster - it’s not very exciting when it just goes very fast, you need sudden twists, turns, ups and downs to get your desired gut reaction. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [October 16, 2012, 11:51am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/32 "2012-10-16T11:51:04Z")
> [@coremelt](#): > > I’m guessing he pulled the chute a long time before he slowed down to standard terminal velocity. His Parachute was designed for high speed opening. > > Anyone seen a website with detailed charts on his speed over time throughout the descent? I posted the following in the other Stratos thread in this forum. Months ago I did an Excel spreadsheet simulating his freefall. I predicted a peak velocity of 860 MPH for him, and he actually hit 833, so I’m calling my results “close enough.” By my estimates: -he was traveling at about 150 MPH when he popped his chute at 9000 feet elevation (4500 feet above local terrain). This is likely very close to terminal velocity for that altitude. -he hit his peak speed at an altitude of around 88,000 feet, after which he began slowing down. -his peak decel rate was about 0.6 g’s. At that point, he felt an upward aero drag force equivalent to 1.6 times his body weight; factor in gravity pulling down with 1x his body weight, and so a maximum decel rate of 0.6 g’s. -He would have had very little sensation of speed for a long time; the relative motion of the earth toward him would have been difficult to perceive until he reached lower altitudes, and the wind drag didn’t build up to appreciable levels for a long time, either. Downward acceleration was in excess of 0.8 g’s for the first 30 seconds of his dive (in other words, he perceived something quite close to weightlessness for that length of time). Additional: he did experience some temperature rise from compressive heating of the air in front of him, but his modest speed (Mach ~1) combined with the very low ambient temp (-50F) meant that the highest temperature he saw, at least until getting close to the ground, was only a few degrees above zero F. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [October 16, 2012, 1:21pm UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/33 "2012-10-16T13:21:07Z")
> [@coremelt](#): > > Anyone seen a website with detailed charts on his speed over time throughout the descent? > [@Machine\_Elf](#): > > Months ago I did an Excel spreadsheet simulating his freefall. And [here’s my plots.](http://s7.postimage.org/5ue4bm7y1/Baumgartner_s_estimate_freefall_data.jpg) Again, not real-world data, just my simulation (although I think it’s reasonably accurate). I watched part of his ascent on Sunday (from about 80,000 feet and higher), and the local pressures they were reporting (and therefore the local densities) were slightly higher than what my atmospheric model has (about a 1/4-psi off); that may help explain why his actual peak velocity was slightly lower than I predicted, and why his total freefall duration was slightly longer than I predicted. Also, in my previous post I was misreading my own temperature plot. His actual peak ram air temperature was about 11 degrees C. That’s still only about 50F, so not anything for him to have been worried about. My model also accounted for the slight reduction in gravity that he experienced (about a 1% drop at his peak altitude) due to being farther from the center of the earth. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [October 19, 2012, 12:37am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/34 "2012-10-19T00:37:31Z")
> [@Hail\_Ants](#): > > I watched it live and _ **my first thought** _ was that, he had the highest freefall, the highest balloon flight, and probably the fastest freefall (plus Mach 1) so I wouldn’t be surprised if he deliberately let Kittenger keep the longest freefall record by a few seconds. Pure speculation, but still… Actually that was my _second_ thought. My first thought watching it live was, _“Holy shit, he’s gone into a flat spin, he’s going to die!”_ How \*did \*he stop spinning without deploying his drogue chute (which would have prevented him from going supersonic)? ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [October 19, 2012, 1:21am UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/35 "2012-10-19T01:21:30Z")
Hijacking the conversation back to the OP: So, is the probable answer some combination of a) the drogue chute, and b) a less aerodynamic suit? ---
**Author:** ![chargerrich](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chargerrich/32/5399_2.png) [@chargerrich](https://boards.straightdope.com/u/chargerrich)\ **Post date:** [October 19, 2012, 2:46pm UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/36 "2012-10-19T14:46:56Z")
> [@Bumbershoot](#): > > Kittinger used a drogue chute for stability, so even though he was falling very fast, his average rate of descent was slower the Baumgartner’s. Kittinger’s top speed was 614 mph, Baumgartner’s was 834 mph. > > Also, because he used a drogue, he wasn’t technically in freefall. I am sure I am probably missing something here with the thinning atmosphere at high altitude, but doesn’t terminal velocity of a human peak at around 200MPH? So did he slow down as he reached lower altitudes and more resistance? ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [October 19, 2012, 3:04pm UTC](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740/37 "2012-10-19T15:04:40Z")
> [@chargerrich](#): > > I am sure I am probably missing something here with the thinning atmosphere at high altitude, but doesn’t terminal velocity of a human peak at around 200MPH? > > So did he slow down as he reached lower altitudes and more resistance? Terminal velocity is a function of the size/shape of the object AND the density of the fluid medium through which the object is falling. Objects falling through high-altitude air have a much higher terminal velocity than they do when falling through sea-level air because high-altitude air is far less dense. At 88,000 feet - right around where Baumgartner hit his peak speed - the air density is about 2% that of sea-level air. As he fell farther and farther down, he encountered more dense air, which gradually decelerated him to something close to 150-200 MPH before he deployed his parachute. [Previous page](https://boards.straightdope.com/t/world-record-sky-dive-today-why-was-his-freefall-time-less-than-the-previous-record/637740.md?page=1)