That's not a vent, that's a rant. :-D

Calvin

All Boeing commercial aircraft are fly-by-cable. All (I think all, I know most are at least) of Airbus' commercial aircraft are fly-by-wire. Since Airbus is approaching the 50% marketshare, I'd guess around 40% of the planes flying are fly-by-wire.

Hmm, fly by cable, fly by wire, fly by night...
I know the difference in this situaton, but isnt a cable just a big wire?

Either way, I thought that the air control surfaces (rudders, ailerons) were actuated by hydraulics. And that is what caused the crash of a plane about 10 years ago near pittsburg - the hydraulics froze or something, forcing the rudder hard to one side. Pilots would never be able to exert enough force to move the control surfaces with their feet and hands.

I would have to verify with my cousin (works at Boeing) but I think the 777 is fly by wire. Or, maybe not... but it was at least the first aircraft of its kind designed entirely on computers using CAD/CAE.

By one definition, a cable is a collection of wires. But in this case, a cable is ``a wire or wire rope by which force is exerted to control or operate a mechanism''. (Merriam-Webster)

"Fly-by-wire" in this definition means electronic input to the main control surfaces via computer (among many other things like fuel delivery, . This is much like the newer Mercedes and BMW's. There is no throttle cable in those cars. When you depress on the accelerator, an electronic pulse is sent to the computer and the throttles are opened accordingly. As a commercial pilot, I can vouch for the benefits of such a system. It has been available in military aircraft for years. The Concorde was the first commercial fly-by-wire aircraft but most new aircraft produced after 1991 made by Boeing (B-777) and Airbus (A-330) are fly-by-wire aircraft.

It turns out the 777 is fly-by-wire and the A300 and A310 are fly-by-cable.

Fly-by-cable is where the pilot mechanically triggers the hydrolics that manipulate the control surface (or in the way old school days, mechanically manipulate the control surface with no hydrolics). Fly-by-wire does this with electrical impulses, the feeling of 'moving' the control surface is simulated by attaching a weight to the input device (stick/yolk) that provides the increased strength needed to move a device in different conditions (hard to explain, but if you want, I can try). Fly-by-light is the same as fly-by-wire except with fiber optics and light pulses instead of electrical. I think the LockMart JSF is the first aircraft to use this, but FBL appears in the V-22 acronym list as Fly-by-Light also, so maybe the V-22 uses it also.

Why is fly by wire better than fly by cable? It would seem like cable would be less likely to fail.

Why is fly by wire better than fly by cable? It would seem like cable would be less likely to fail.

No.

Cable is a mechanical construct, with bell-cranks, pivots, bearings, pulleys, any number of components that can break, stretch, wear out, or fail in other ways.

Fly by wire means you replace all that mechanical paraphernalia with a simple wire. All it has to do is stay in one piece (no reason for it to do otherwise, is there?) and carry the occasional electron or two from one end to the other. Simpler and more reliable.

tanstaafl.

Right, it puts all the work on other things like the servos, pumps and other little fun beasties that wouldn't exist if not for FBW.

The F16 was fly by wire wasn't it? If I recall correctly, the 'wire' portion of many of the planes was severed from vibration and high G's. Subsequently, the 'Fly' portion of the vehicle was disabled. This usually happend when the plane was located many thousands of feet above solid earth.

There were no indications of a problem before this happened. Several planes crashed before the cause was discovered.

Is it better? Hmmmmm......

Also, as I understand it, many new-fangled planes (the F-22 pops to mind) are extraordinarily maneuverable because they are on the verge of instability, and without computers making thousands of corrections a second, wouldn't fly at all. And those corrections would be impossible if it weren't being flown by wire.

That's exactly the sort of thinking that is preventing wider adoption of fly by wire. ("good enough for my car is good enough for the air-o-plane...")

Calvin

The F16 was fly by wire wasn't it? If I recall correctly, the 'wire' portion of many of the planes was severed from vibration and high G's.

Yeah, I saw that TV special, too. (Was that Nova or 60 Minutes? Don't remember.) Scary stuff.

Thing is, mechanical and hydraulic systems can fail, too. I, um, havent gotten on an airplane in a long time.

There are steer by wire and brake by wire (further away) development programs under way at companies such as SKF, Motorola, TRW, and Delphi. The current 'Quadrasteer' system on some GM trucks has no mechanical linkages between the steering wheel and the rear steering actuators.

-Zeke

Actually most all Fighter planes still in Service use computers to correct, at the speeds they use one bullethole can change their aerodynamics to the point it would almost impossible to correct manually without putting the pilot into some serious G's first.

You cannot have a very maneuverable aircraft that is completely stable, the two are mutually exclusive. For aircraft that need to be extremely stable (think freighters, tankers, commercial), they sacrifice maneuverability to acheive the stability.

Due to the weight differences, it is possible to have layers upon layers upon layers upon layers of backup systems for a FBW system. A cable system is much heavier, so it only has one or two backup systems.

Oh *please* someone tell the German television stations that we really need Red Dwarf over here!! Saw some of the early stuff back in NZ and would love to catch some more of it some time. Hmmm, can you get BBC2 on satelite?

Not easily, I BBC 2 used to transmit in the clear on analogue satellite (possibly one of the eutelsats) but I doubt it's still done.

Yeah, [bold]unstable airframes[/bold] are all the rage for modern fighter jets. F22, JSF, Eurofighter Typhoon etc. All are aerodynamically unstable and [bold]require[/bold] Fly-By-Wire technology to even get off of the ground.

In reply to:

---

There are steer by wire and brake by wire (further away) development programs under way at companies...

---

Mercedes Benz 2003 SL uses brake by wire. It does have a mechanical backup though.

Nice and comforting, esp since I have seen quite a few reports of throttle by wire going out (on new cars - what happens to people like me that drive 20 year old cars 20 years from now??)

You should know better than me Andy, but I thought you could get our digital satelite over most of Europe.
In caravan/motorhome magazines, they advertise self seeking satellite dishes with this claim, also for use by long distance truckers.

I've just been in Majorca and they are certainly advertising set ups to get 1,2,ITV,4 and 5, with a free card, in shop windows.

I think you forget that the pea in question is a Minnesota county fair prize winning pea!

This is not a pea to be messed with.

This is a pea even a Bolo would think twice about!

Do not underestimate the power of the pea...

Funny,

I'd never heard it before. I must have excellent taste in commedians....