Falling faster: The surprising leap of Felix Baumgartner

Research news - Five years ago the Austrian daredevil Felix Baumgartner broke the sound barrier during his free fall from an altitude of almost 39 kilometers. Now researchers at the Technical University of Munich (TUM) have analyzed the fluid dynamics of his descent. The surprising result: Baumgartner, with his irregularly shaped equipment, fell faster than a smooth, symmetrical body would have. Felix Baumgartner's daring leap from the stratosphere on October 14, 2012 set a world record: It was the first time ever that a human being had broken the sound barrier while in free fall. Prof. Ulrich Walter, head of the TUM Chair for Astronautics, recognized Baumgartner's record leap as a unique opportunity to study how an irregularly shaped object falls: "In the past nobody knew how rough and irregularly formed surfaces like the folds of the protective suit and the backpack Baumgartner wore would impact fluid dynamics." - A jump raises plenty of questions. The first surprise came shortly after the landing, recalls Walter, who followed the jump live as scientific advisor to the Stratos team: "Our calculations, based on the fluid dynamics of a smooth body, indicated that Baumgartner would need to jump from an altitude of about 37 kilometers in order to break through the sound barrier, i.e. to fall faster than Mach 1 or about 1200 kilometers per hour. But in reality Baumgartner reached a much higher speed of Mach 1.25." But how could an athlete equipped with a protective suit and a backpack fall faster than a symmetrically shaped object with a smooth surface?