Paris has long been at the heart of the history of flight. It is where the Montgolfier brothers ascended in the first hot-air balloon in 1783, and where Charles Lindbergh completed the first solo transatlantic aeroplane journey in 1927. Next year, if all goes to plan, Paris will be the site of another industry first when Volocopter, a German maker of electric aircraft, launches a flying-taxi service during the Olympic Games. At the Paris Airshow in June the company, and some of its rivals, paraded a new generation of battery-powered flying machines designed for urban transport. The electrification of aviation...