Airbus Helicopters is today commemorating 50 years since the first flight of its emblematic fenestron shrouded tailrotor. Fifty years ago today, the first fenestron flew on the second prototype of the Sud Aviation Gazelle. In the ensuing years, the configuration has become an integral part of designs for the companies that have emerged from Sud, including Aerospatiale, Eurocopter, and Airbus Helicopters.
The initial idea behind shrouding the tail rotor was to safeguard workers on the ground and protect the tail rotor in forward flight and in complicated operational environments, such as working around high-voltage power lines. Later designs incorporated sound-reduction benefits.
Originally called the “fenestrou,” which is Provençal for “little window,” the term evolved into fenestron. It was first certified on the Gazelle in 1972 and then subsequently integrated into the first single-engine Dauphin prototype. A second generation all-composite design with a 20 percent larger diameter was launched in the late 1970s and a third generation, fitted onto the H135, optimized noise levels using uneven blade settings. This design was later incorporated into the H130 and the H145. The latest refinement of the fenestron is flying aboard the new H160 medium twin. It is larger and is canted 12 degrees for improved performance and stability with higher payloads at lower speeds.