Helikopter - El.drift av halerotor? - AW&ST

Fra min korrespondent i Sandnes har jeg mottatt følgende: Ref. bloggen din i dag og Leonardo med el-halerotor. Vedlagte bilde viser halerotoren på helien min. Har vært vanlig i mange år med el-motordrift på mange RC-helikopter. Problemfritt, enkelt og greit! (Red.) Tail Rotor Electrification Could Pave Way For Rotary-Wing Hybridization Tony Osborne  Despite the rush toward electric vertical-takeoff-and-landing (eVTOL) air systems and urban air mobility, helicopter manufacturers and their suppliers are continuing to explore the potential electrification of anti-torque systems on conventional helicopters. The approach is regarded as a possible first step toward the hybridization of rotorcraft and could bring about key ancillary benefits in terms of performance, safety and environmental aircraft. Leonardo has performed 10 hr. of testing with AW139-scale electric tail rotor ZF contends a 1,000-kW motor will be needed for a light twin-engine helicopter anti-torque system Leonardo has been studying the potential of the technology in conjunction with the UK’s University of Bristol through the European Union’s Clean Sky 1 initiative, ground testing an air-cooled electric tail rotor on the tail boom of an AW139 medium twin-engine aircraft for 10 hr. in the company’s whirl tower facilities in Cascina Costa near Milan. “This is not a technology ready for implementation, but there is a lot of potential,” says Roberto Garavaglia, Leonardo’s president of strategy and business development. On a conventional helicopter, the tail rotor runs by using a shaft connected to the main gearbox via the tail boom to a gearbox that synchronizes the tail rotor’s movement with that of the main rotor. Introducing an electric anti-torque system could immediately dispense with the complex network of shafts and gearboxes, eliminating the need for heavy maintenance on those components. Such a system would probably derive its power from a generator driven by the turbine, an approach likely to be used in distributed hybrid-powered eVTOL air vehicles being envisioned by some manufacturers.

Leonardo’s electric tail rotor demonstrator was scaled to the size of an AW139 medium-twin-engine helo. Credit: Leonardo Helicopters

In addition to reducing maintenance costs, the electric tail rotor can be decoupled from the conventional main rotor. On the ground for example, this would allow the tail rotor to be shut down entirely, making the on- and offloading of passengers safer, while the main rotors keep running. In the emergency medical service mission, where stretcher-bound patients are often loaded on board via clam-shell doors in the rear fuselage of light helicopters, shutting down the tail rotor would eliminate the safety risk posed by running rotors. “In the cruise, most of the stability in forward flight is provided by the vertical and horizontal stabilizers,” Garavaglia says. But reducing the speed of the electric tail rotor or optimizing it in conjunction with that of the main rotors—particularly during cruise—could help reduce fuel consumption as well as the noise levels that result from the main and tail rotors’ interactions, he notes. A helicopter company test pilot tells Aviation Week that another benefit could be to link tail rotor performance to density altitude so that performance could be improved in low-density situations, such as those associated with hot and high conditions. An electric tail rotor also could compensate for the loss of tail rotor thrust and improve aircraft control, especially for smaller helicopters during severe turbulence. Leonardo’s work on an electric rotor paved the way for the technology to reach a technology readiness level of four—component validation in a laboratory environment. In 2017, Italy bestowed the National Award for Innovation to the company for this work. An electric tail rotor would make it easier to design a folding tail boom, too, allowing the aircraft to take up less space in a hangar or perhaps on a ship, if applied to a naval aircraft. Weight savings are likely to be neutral, however, because while  the electric tail rotor allows the removal of the heavy tail rotor gearbox and shaft, it still requires the generator, motor and extra wiring. At Heli-Expo, Germany’s ZF, a specialist in producing aviation gearboxes, displayed a mockup of an electric tail rotor it plans to demonstrate this year. Initially, the use of a 1,000-kW motor is being explored, but company officials note that the technology is scalable across the spectrum of helicopter sizes and takeoff weights. ZF expects such a motor will be needed to support the tail rotor of a light-twin helicopter model up to around a 4-metric-ton maximum gross weight. The company also plans to look at the potential of an electric shrouded anti-torque system, such as Airbus’ fenestron system, to see if the technology could be applied there. “We do not believe this is a technology that can be applied retroactively because of the challenges associated with certification and testing. Instead, it would be better used on a new-build helicopter,” says Lars Mitter, head of customer services at ZF Aviation Technology.