When the capsule's hatch rolled aside and Felix Baumgartner saw the black frame of the vast emptiness and a thin realm of blue 39 km below, what did he feel? What could a human feel? For a person like me -and Mr. Bean, of course-, who gets dizzy at the sight from the top of the diving board or feels incapable of bungee-jumping from scarcely 150 m, the sense of being at the edge of a capsule ascending unflappably into space is something that a million of pounds could not buy. Apart from the physical demand of the jump, technical developments and economical efforts, Felix being suspended in the Universe is the most appealing deed for me: the capsule, being fatefully carried away; the oxygen, ticking down unmercifully. And three, four, six seconds before jumping that account for a whole eternity.
As for the speed of sound, I guess Felix broke the limit of the sound, although the information is contradictory and surprisingly imprecise. In any case, I think that any statements made in this direction need to be more thoroughly explained.
Leaving aside the suspicion that a large percentage of people who have written and talked about the speed of sound does not know how much it really is or what it is, one can read that Felix reached Mach (M) 1.25 at a maximum velocity of 833.9 mph. However, the video shows different figures. In the video, it seems that Felix reaches a maximum of 729 mph and that remains there (terminal velocity) for about 20 - 25 seconds, after which he starts decelerating. (The video is cut in the best moment, but listen to the voice of the man). 729 mph is 325 mps, which is below 340 mps, the speed of sound in air at NTP conditions (atmospheric pressure and 20 Celsius). Of course, the speed of sound is lower high up in the stratosphere and, with this consideration, Felix's flight was probably supersonic. How much lower? If we take 833.9 mph as M=1.25, 833.9 mph is 372.5 mps, which gives a hypothetical speed of sound of only 298 mps. If 729 mph is the true maximum speed at which Felix traveled, his supersonic flight would have been M = 1.09.
Taken as a simple and ideal exercise, as good as I could, I drew the evolution of Felix's fall speed and estimated the acceleration he suffered from the data of the video. I have been unable to paste it here. The maximum acceleration takes place at the beginning of the fall, of course, but only amounts to 9.2 m/(s^2), approx. Given the altitude and the latitude (35N, Alburquerque), one would expect 9.74 m/(s^2), so let's assume that the difference is due to friction or/and drag or whatever (spinning, Magnus effect?, etc). Then, the acceleration felt by Felix reduces, although it is irregular, as expected. Both acceleration and deceleration shows peaks (up to 2.2g in deceleration) but, who knows, I just collected the data with pencil stopping repeatedly the video... .
I calculated as well the distance traveled until deceleration starts (first minute of fall) and got about 14 km. If this is correct, it means that when Felix started decelerating he was still in the stratosphere. The average velocity of fall during the acceleration part is, then, about 522 mph.
(PLEASE, LEAVE YOUR COMMENT).
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