What Is FlyByWire?

Tue Nov 16, 1999 4:14 am

Hey Everyone,
I always wanted to know what Is Fly By Wire. I noticed that new aircrafts like A340 and A330 and others dont have a Yoke. The only thing i saw was this little joystick on the left hand side of the pilot, and the right hand side of the co-pilot. Is that Fly By Wire? Wouldnt that be more harder to fly using the left hand then using a big Stck or Yoke with both hands? Thats a wierd thing. Well anyway, what is Fly By Wire?  
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Joined: Wed May 26, 1999 10:07 am

RE: What Is FlyByWire?

Tue Nov 16, 1999 4:27 am

There are many people more educated about flight systems than me but I'll give you enough to settle you for now. In a standard control aircraft the control surfaces (rudder, tail, ailerons, etc.) are moved by the motion of the yoke by cables (not electric cables but wire rope) or by hydraulic fluid, similar to the power brakes on an automobile, you push on a plunger that sends fluid to hydraulic cylinders which perform the action.

In a fly by wire system the motion is made by the joystick in the cockpit, the motion in the stick is picked up by electronic sensors in the joystick which then send that signal to the three (triple redundant) flight computers which evaluate the signal and then send a signal electrically to electric hydraulic pumps or to electric motors which move the control surfaces that are deemed necessary for the action the pilot inputs. This system will not allow the pilots to make a move that the computers deem unnecessary or dangerous. I am not starting the usual fight here but that is what happened to the airbus at the Paris Air Show, the aircraft was told that it was time to land, the aircraft began the landing procedure into the trees and the aircraft caught fire and crashed. Any attempt by the pilots to pull the plane out was ignored as the computer was landing the plane and the pilots did not shut off the automated landing system. This problem was found to be in the software and was fixed, but as sure as the lord made little green apples there will be other bugs that come out. All we can hope for is they are discovered in simulators on the ground, not at cruising altitude.

Posts: 127
Joined: Sat May 21, 2011 1:33 pm

RE: What Is FlyByWire?

Tue Nov 16, 1999 4:30 am

Fly by wire is not directly the reason for the Airbus 'sidestick', as the 777 (with a conventional control column) is also fly-by wire.

It is the future of aircraft design, and no new aircraft design of the future will even not be fly-by-wire until a replacement is found for it.

As simply as possible, Fly by wire is a different way of commanding flight controls on an airliner. The flight controls are, of course, still moved by hydraulic power as they have been for many years, but in a fly-by-wire aircraft the signals are sent to the hydraulic jacks and actuators on the control surfaces electronically, rather than mechanically. This has saved the use of heavy mechanical rods, levers and springs which were previously used, replaced with wires which results in large weight savings for aircraft which makes them more efficient.

Also with fly-by-wire, no physical effort is required to move the controls, so a sidestick was introduced by Airbus giving the pilot an uncluttered view of the instruments, allowing the instruments to be larger, and also allowing us to have lunch in comfort at last!

That was, of course, a simple explanation of how it works, the electrical signals actually pass through an array of computers which transmit further electrical signals to the control surfaces, and it is all fairly techincal, much more than I know at least. Nevertheless I hope you are a little clearer as to the controls which will be present on new aircraft in years and decades to come.

A320/330 pilot.

Good Answers

Tue Nov 16, 1999 4:45 am

Thanks to bothe Phil330 and Pmk for that explanation. I understand better now. But what is wierd is that well aint it easier having a yoke in front then contorlling a 1000 ton aircraft with your LEFT hand? WoW, what an invention.  

Pros And Cons

Tue Nov 16, 1999 4:52 am

FBW design is obviously the way foreward for aircraft design, but Boeing and airbus seem to have two slightly different ways of implementing it.

I have never flown FBW airbusses so I am probably not in the best of positions to debate, however I have often asked myself why Boeing retained the traditional control column on their FBW B777 while Airbus swears by the sidestick.

Surely there must be more to it than marketing and PR! Discussing this with fellow aviators (admittedly Boeing Drivers) there appears to be the notion that a control column gives more 'information' when used in a multi-crew environment. The non flying pilot sees on his column the direction and amplitude of control displacement made by the flying pilot, both pilots see what the autopilot is doing. Both pilots' controls are physically connected making handover/takover of control direct. The 'bus philosophy is suitable to a single pilot aircraft (eg. a fighter) where these aspects are not issues. I am sure the sidestick is a very safe and well engineered piece of equipement but I would like some 'bus drivers to give me their thoughts on wether it is truly the marvel it is said to be or if maybe the gentlemen at Toulouse added a bit of 'originality' to modern aircraft design.
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Joined: Sat May 21, 2011 1:33 pm

RE: What Is FlyByWire?

Tue Nov 16, 1999 6:00 am

Bird Strike,

I must admit as a devoted 757 driver I was reluctant to move onto the 'sidestick' philosopy last year, but have found it has a number of advantages over the control column, and I would now be reluctant to go back to 'Boeing'. In fact of the 10 or so 'converters' I have spoken to only 1 said he prefered the Boeing.

Those things aside what you say is correct, although we come across control takeovers from pilot to pilot very rarely. It is much more common to take over from the autopilot than from the other pilot.

Another advantage of the Airbus 'fly-by-wire' concept is that because the flying is computer controlled (i.e. the pilots actions are interpreted and translated by a computer) all Airbus types feel alike when you fly them as they are all 'tuned' to fly the same. I fly the A320, A321 and A330 and the similarities are remarkable.

Training for the A320 was more difficult than for the Boeing since it was impossible to 'follow through' the actions of the instructor as the controls are in no way linked. You do get used to it very quickly, though, and having a proper table to eat from is a real bonus!

A320/330 pilot.
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Joined: Wed Sep 08, 1999 12:01 pm

Bird Strike

Tue Nov 16, 1999 8:11 am

Boeing didn't adopt the sidestick because they wanted something different and unique from Airbus.

Pros And Cons

Tue Nov 16, 1999 8:26 am

AC_A340, Don't you think the ones who were being different were Airbus? there's quite a lot of history behind the control column and I'm sure both Boeing and Airbus did their homework well when deciding about the future of such a fundamental piece of hardware. As I said earlier, Mr. Boeing built my office and so far I've always felt at home...That may change soon though as our company is replacing our 76's with 330's. I'm curious to see airbus' side of the story!

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