 Titanium was still expensive and not widely used because it was difficult to machine.The Arrow's thin wing required aviation's first hydraulic system to supply enough force to the control surfaces, while using small actuators and piping.A rudimentary fly-by-wire system was employed, in which the pilot's input was detected by a series of pressure-sensitive transducers in the stick, and their signal was sent to an electronic control servo that operated the valves in the hydraulic system to move the various flight controls.