FLIGHT MANAGAMENT SYSTEMS

Flight Management Systems

Flight Management Systems

Fly-by-Wire

Cable control (fly-by-wire, FBW, Fly in spirit by wire (electric)) is a control technology for aircraft.

In contrast to classical control, in which the control movements of the pilots by steel cables, rods or hydraulic systems to the control surfaces or rotors are transmitted to sit at Fly-by-wire sensors (e.g. potentiometers ) to the controls (stick, pedals , etc.) (Aviation Safety and Pilot Control, 2000).

In general, it is assumed that the data transferred by wire flight control commands originate from a computer. This pilot is also supported and freed from routine tasks (Fielding, 2001).

Concept

Mechanical and Fly-by-wire FCS

The early generations of flight control systems were mechanically-based. Mechanical flight control system direct mechanical linkages were used between the pilot's cockpit controls (pitch/roll stick and rudder pedals) and the control surfaces that manoeuvre the aircraft, which are for this example: tailplane, ailerons and rudder. This arrangement is inherently of high integrity, in terms of probability of loss of aircraft control, and provides us with a very visible baseline for explaining FCS developments. Digital fly-by-wire flight control system Subsequent generations of FCS have been developed on programmes such as Tornado, Jaguar Fly-by-wire and the Experimental Aircraft Programme towards the current quadruplex digital fly-by-wire type, for example, on Eurofighter Typhoon (Stevens and Lewis, 2002). The main emphasis is now on digital computing with the use of inertial motion and air stream sensor units; the direct mechanical linkages between the cockpit controls and the control surfaces have been removed and replaced with electrical signaling with direct motion commands, hence the term 'fly-by-wire' (Stevens and Lewis, 2002). This arrangement provides a significant reduction in mechanical complexity. In order to achieve the same level of integrity as that achieved with the earlier mechanical systems, multiple signal sources and several lanes of computing are necessary to provide redundancy, these being cross-monitored in order to isolate any failed equipment and to ensure safe operation. The current military aircraft trend is towards triplex redundant architectures with reliance on both cross-lane and in-lane monitoring to achieve the required level of integrity, and hence the associated safety of system operation (Aviation Safety and Pilot Control, 2000).

The movements of the pilots at the controls (e.g. on the side stick ), when the fly-by-wire electrical signals are converted into, then by servo motors or hydraulic cylinders by means of controlled, are valves electric back in the control surfaces reacted to movements (Flight Control Design - Best Practices, 2003).

The control signals are transmitted purely electric. An extension of the fly-by-wire concept is the control signals from execution by a flight control computer can run that. It also provides a fly-by-wire automatic and thus much more rapid response to flight path and attitude changes, as for example, by turbulence caused (Flight Control Design - Best Practices, 2003).

History

The development of such systems began when we saw an opportunity through servo actuators, the laborious and difficult serviceable rods, cable systems and hydraulics, electrical ...