Fly-by-wire
Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface.
The pilot may not be fully aware of all the control outputs acting to affect the outcome, only that the aircraft is reacting as expected.
Gyroscopes and sensors such as accelerometers are mounted in an aircraft to sense rotation on the pitch, roll and yaw axes.
Any movement (from straight and level flight for example) results in signals to the computer, which can automatically move control actuators to stabilize the aircraft.
A number of control movement steps can be automatically performed, reducing workload of the pilot or groundcrew and speeding up flight-checks.
[citation needed] Some aircraft, the Panavia Tornado for example, retain a very basic hydro-mechanical backup system for limited flight control capability on losing electrical power; in the case of the Tornado this allows rudimentary control of the stabilators only for pitch and roll axis movements.
In 1934, Karl Otto Altvater [de] filed a patent about the automatic-electronic system, which flared the aircraft, when it was close to the ground.
[10] In 1941, while being an engineer at Siemens, developed and tested the first fly-by-wire system for the Heinkel He 111, in which the aircraft was fully controlled by electronic impulses.
This system also included solid-state components and system redundancy, was designed to be integrated with a computerised navigation and automatic search and track radar, was flyable from ground control with data uplink and downlink, and provided artificial feel (feedback) to the pilot.
53-2280)[14] The first pure electronic fly-by-wire aircraft with no mechanical or hydraulic backup was the Apollo Lunar Landing Training Vehicle (LLTV), first flown in 1968.
[15] This was preceded in 1964 by the Lunar Landing Research Vehicle (LLRV) which pioneered fly-by-wire flight with no mechanical backup.
As of June 2024, over 11,000 A320 family aircraft, variants included, are operational around the world, making it one of the best-selling commercial jets.
The 777 used ARINC 629 buses to connect primary flight computers (PFCs) with actuator-control electronics units (ACEs).
Digital signal processing can receive and interpret input from multiple sensors simultaneously (such as the altimeters and the pitot tubes) and adjust the controls in real time.
The primary benefit for such aircraft is more maneuverability during combat and training flights, and the so-called "carefree handling" because stalling, spinning and other undesirable performances are prevented automatically by the computers.
Hence virtually all fly-by-wire flight control systems are either triply or quadruply redundant in their computers and electronics.
If one computer begins to give aberrant results for any reason, potentially including software or hardware failures or flawed input data, then the combined system is designed to exclude the results from that computer in deciding the appropriate actions for the flight controls.
Depending on specific system details there may be the potential to reboot an aberrant flight control computer, or to reincorporate its inputs if they return to agreement.
Complex logic exists to deal with multiple failures, which may prompt the system to revert to simpler back-up modes.
[25][26] In addition, most of the early digital fly-by-wire aircraft also had an analog electrical, mechanical, or hydraulic back-up flight control system.
As a result, in such conditions, the flight control systems commands the engines to increase thrust without pilot intervention.
In economy cruise modes, the flight control systems adjust the throttles and fuel tank selections precisely.
FADEC reduces rudder drag needed to compensate for sideways flight from unbalanced engine thrust.
[citation needed] Fly-by-optics is sometimes used instead of fly-by-wire because it offers a higher data transfer rate, immunity to electromagnetic interference and lighter weight.
Fly-by-light has the effect of decreasing electro-magnetic disturbances to sensors in comparison to more common fly-by-wire control systems.
[42] Wiring adds a considerable amount of weight to an aircraft; therefore, researchers are exploring implementing fly-by-wireless solutions.
[44] It is reported that enhancements are mostly software upgrades to existing fully computerized digital fly-by-wire flight control systems.
The Dassault Falcon 7X and Embraer Legacy 500 business jets have flight computers that can partially compensate for engine-out scenarios by adjusting thrust levels and control inputs, but still require pilots to respond appropriately.
