A Fenestron's a shrouded tail rotor of a helicopter that's essentially a ducted fan. The housing's integral with the tail skin, and, like the conventional tail rotor it replaces,'s intended to counteract the torque of the main rotor. It was original conceived by Sud Aviation in the 1960s. Sud Aviation became part of Aerospatiale which merged with Daimler-Benz Aerospace AG to form Eurocopter in 1992. Eurocopter has since become part of the European Aeronautic Defence and Space Company (EADS). Wh… (More on Fenestron)