Since helicopters appeared some 80 years in the past, they’ve used a single high-speed tail rotor to counteract the torque of the principle rotor, stabilizing the plane in flight. However that rotor is each the important thing supply of noise for helicopters and an enormous security threat whereas on the bottom.
Now veteran helicopter producer Bell has a design to interchange the mechanically pushed tail rotor meeting with 4 a lot smaller, shrouded electrical followers. The brand new system, unveiled this week after footage of its demonstration leaked on-line, will significantly muffle the plane’s sound. It additionally has the potential to make helicopters safer and simpler to fly, and will grease the skids for future electrified plane of every kind.
Developed over the past two years and examined on the firm’s facility in Mirabel, Quebec, the “electrically distributed anti-torque” system, or EDAT for brief, resembles a quadcopter drone set vertically contained in the Bell 429 helicopter’s rear vertical fin. EDAT makes use of the 4 variable-speed propellers to operate the identical manner a traditional tail rotor does, by adjusting airflow via the blades to each hold the fuselage regular and intention it in numerous instructions. Pilots use foot pedals to regulate this movement, permitting the plane to “yaw” left and proper whereas, say, in a hover.
The brand new system’s trick is within the management mechanism. A standard tail rotor at all times operates at full velocity as a result of it’s mechanically linked to the principle rotor; pilots alter the pitch of the blades to regulate airflow. In contrast, the brand new electrical followers management airflow by working at totally different speeds. “We removed all of the mechanical linkages that change the pitch of the blades and changed them with electrical wires,” Bell program supervisor Eric Sinusas stated. “We realized that we don’t really need that driveshaft and gearbox that we’ve had for the final 80 or so years.”
That transition required appreciable engineering effort and high-precision software program to make the system protected and dependable. EDAT doesn’t run off a battery, however as an alternative attracts energy from a generator connected to the helicopter’s turbine engine. That engine will nonetheless generate its typical noise, however the racket usually generated by the tail rotor—because the rotor suggestions cross via the air at excessive speeds—can be diminished. Although Bell hasn’t but disclosed the proportion in noise discount, the corporate says it’s “vital.”
Sinusas stated his crew selected the four-fan array as a result of a single bigger electrical rotor can be heavier and fewer responsive, with extra sluggish modifications in velocity. Smaller electrical followers are additionally quieter, which was the first motivation for creating the system. “Noise has at all times been there, but it surely actually hasn’t been a precedence to scale back it till lately,” he added. “We’re on the level the place areas are banning helicopter flights due to the noise ranges, and that prompted us to ask how we will clear up this.”
Changing the tail rotor to an all-electric system solves different issues. It improves stability as a result of the rotors don’t should be continuously in movement, in contrast to a traditional tail rotor. The pilot can really flip the followers off in ahead flight, because the vertical fin they’re embedded inside stabilizes the plane. (Standard tail rotors are solely wanted for hovering and low-speed flight, however they run continuously due to the hyperlink to the principle engine.) Additionally, as a result of the system is fly-by-wire, which means managed electrically reasonably than via mechanical linkages, the pc can management the followers. This will probably remove the necessity for the pilot to have to make use of the pedals in any respect. An automatic model of the EDAT would thus be a type of autopilot.