On August 16, 1960 he made the final jump from the Excelsior III at 102,800 feet (31,300 m). He was in freefall for 4 minutes and 36 seconds reaching a maximum speed of 614 mph (988 km/h) before opening his parachute at 18,000 feet (5,500 m). He set records for highest balloon ascent, highest parachute jump, longest freefall and fastest speed by a man through the atmosphere. [1]
It is claimed that he broke the sound barrier in his freefall.
I suppose they could make the appropriate calculations to prove otherwise prior to "flight", but I would have worried I was going to come back a big burning greaseball.