Editing Aircraft flight control system (section)

====Artificial feel devices====
With purely mechanical flight control systems, the aerodynamic forces on the control surfaces are transmitted through the mechanisms and are felt directly by the pilot, allowing tactile feedback of airspeed. With hydromechanical flight control systems, the load on the surfaces cannot be felt and there is a risk of overstressing the aircraft through excessive control surface movement. To overcome this problem, artificial feel systems can be used. For example, for the controls of the [[RAF]]'s [[Avro Vulcan]] jet [[bomber]] and the [[RCAF]]'s [[Avro Canada CF-105 Arrow]] supersonic interceptor (both 1950s-era designs), the required force feedback was achieved by a spring device.<ref>The Arrowheads, pages 57-58, 83-85 (for CF-105 Arrow only).</ref>  The [[Fulcrum (mechanics)|fulcrum]] of this device was moved in proportion to the square of the air speed (for the elevators) to give increased resistance at higher speeds. For the controls of the American [[Vought]] [[F-8 Crusader]] and the LTV [[A-7 Corsair II]] warplanes, a 'bob-weight' was used in the pitch axis of the control stick, giving force feedback that was proportional to the airplane's normal acceleration.{{Citation needed|date=July 2010}}