Reply #10: It's pretty easy to calculate Vt at low altitudes, it's around 60 M/S for a falling human

[mach2]

but is obviously a lot faster that far up. I don't know what air density is at that altitude, I'm surprised a balloon can even get that high...but it's pretty much above the atmosphere so the 1000 mph figure might actually be about right. If he pulls it off (argh, he's 64 YO!)...it will be interesting to hear his impressions, like if there was really any sensation of speed.
:-)