VolocopterThe VoloCity made demonstration flights in Paris over the summerOne of the innovations at this year's Paris Olympics was supposed to be an electric flying taxi service.Germany's Volocopter promised its electric-powered, two-seater aircraft, the VoloCity, would be ferrying passengers around the city.It never happened. Instead the company ran demonstration flights.While missing that deadline was embarrassing, behind the scenes a more serious issue was playing out - Volocopter was urgentl...