Yaw pedals, featuring mechanical linkages to the rear tail fin, as well as sensors to send control inputs to the top rotor controllers to affect yaw.
It's easy to look back at the history of exploration and aviation and feel like there's no mountains left to climb, that the age of the great pioneers is behind us and we're doomed to a future of LCD tanning and monitor hypnosis. But don't try telling that to Pascal Chretien. On August 12, this electrical/aerospace engineer and helicopter pilot took to the air in the world's first untethered, fully electric manned helicopter flight in a prototype machine that he designed and built almost entirely by himself within a 12 month development period. In his 2 minute, 10 second test flight, Chretien beat aviation giant Sikorsky into the record books - but it was not without significant risk. As the man himself puts it: "in case of crash I stand good chances to end up in kebab form."