In 2010, Sikorsky Aircraft introduced “Project Firefly,” an all electric helicopter technology demonstrator based on the S-300C airframe. The intent was to have it flying a year later and set a world record for the first all electric manned helicopter flight. Unfortunately, the company did not make the target date and last year the first all electric powered helicopter flight was achieved by pilot and designer Pascal Chretien in France.
Chretien took a different approach than Sikorsky, rather than use a heavy existing airframe he designed a new lightweight highly energy efficient aircraft. As an electrical engineer and commercial rated helicopter pilot he knew what areas to target. A tail rotor can consume 10 percent of available power, so to eliminate the tail rotor Chretien used a coaxial main rotor system. He employed a second generation asymmetrical rotor blade design which provided a 19% increase in lift over his initial blades. Powered by a lightweight (128 pounds) Lithium ion polymer pouch cell battery pack the two DC powered electric motors provided a total of 43 hp, enough power to lift the required 545 pounds. Each rotor system has its own motor and yaw is controlled by varying the electrical signal to each motor.
In July and August of 2011, the aircraft made 29 flights totaling 99.5 minutes with some flights lasting 6 minutes. Then on 12 August 2011, the world’s first un-tethered manned flight of a helicopter powered only by an electric motor took place at Venelles, France. Chretien hovered above the ground for 2 minutes 10 seconds entering the Guinness World Book of Records.