What is “Fly-by-wire” technology in aviation? What benefits does it have and why is it used in modern airplanes today?
In: Engineering
As others have explained – it means the pilot’s controls send a signal to a motor that moves the control surface. As opposed to an old direct mechanical connection from the controls to the control surfaces or a hydraulic connection.
Benefits can include:
– less effort to move the controls (since the resistance on the wheel/stick/pedals is just ‘fake’ feedback and not the actual force to move the control surfaces against the wind)
– not prone to wear/stress/leaks like physical or hydraulic connections.
– can be overridden. The onboard computer can override inputs that would endanger the aircraft.
– can allow for unstable designs.
The last one is interesting. Historically, aircraft would be built to be stable (i.e. they’d naturally return to stable horizontal flight unless the pilot is acting on the controls). If you grab a kite by its nose and pull it through the air, that’s a fairly stable scenario. But this kind of design kinda means if you’re trying to turn, you’re having to fight against the aircraft that wants to go back to level, straight flight.
Modern fighter aircraft are sometimes designed with “relaxed stability”. This is a bit like grabbing a kite by the rear and trying to push it through the air – it’ll just buck all over the place trying to get away from stable level flight. Such a fighter would be near impossible to fly with physical controls – instead fly-by-wire systems are used which can compensate for this and keep the aircraft stable, while also allowing for greater manoeuvrability when the pilot wants it.
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