Eurocopter has successfully flown a production-capable testbed helicopter using fly-by-light systems to drive its primary flight controls. Known under the awkward cognomen of the active control technology demonstrator/flying helicopter simulator (ACT/FHS), the remarkable rotorcraft is a Eurocopter EC 135 airframe fitted with the new laser light control system. The ACT/FHS’s control system is in many ways similar to the fly-by-wire systems just beginning to enter production as the nerve system of such advanced rotorcraft as the Bell Agusta BA609 civil tiltrotor and NH Industries NH 90 military transport (the latter is due to enter service with the German military in 2004). As with those aircraft, control signals between the ACT/FHS’s pilot stations, flight control computer and actuators for rotor blade control are not transmitted electrically, via wire, but instead optically, via hair-thin optical glass fibers.

aved, the optical system is far less complex, the total number of control system moving parts (always a sensitive issue in the rotorcraft world) is reduced, and the overall handling of the helicopter can be greatly augmented, even over the improved handling reported by pilots of the first fly-by-wire helicopters. Simply put, fiber-optic systems can move more data than wire systems, clearing the way for improved flight control systems, super-stability augmentation and a host of other new technologies still under either design or consideration. Funding for the ACT/FHS is being conducted under the terms of an agreement between the German Aerospace and Space Center (DLR) and the German Armed Forces test center (WTD61). According to the deal, both the German armed forces and German industry can eventually make use of the new fly-by-wire technology.