aviationbuff
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Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 12:01 pm

http://www.flightglobal.com/articles...s-the-wire-out-of-fly-by-wire.html

Quote:
Gulfstream this year could take fly-by-wire to a new level by throwing out the wire. In addition to its tests with fly-by-light control, the Savannah, Georgia-based aircraft maker has been experimenting with a system that will use a wireless channel or channels to pass data back and forth to a spoiler actuator on the company's G550 advanced flight-controls testbed.

 
askr
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 12:16 pm

Wow. Now this is scary news... I bet they will use much better stuff than SOHO wifi, but still, I would pi** my pants if i where to fly in an, effectively, remote controlled plane.
Is this stuff cheaper or lighter?
They still need to route power or hydraulics to the relevant parts of the palne, so will it realy allow tham to save enough weight / money to make it usefull?
ATC-PL Wanabe :) - 2nd application is in... 11 July...
 
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Starlionblue
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 12:27 pm

This has been discussed before. And yes, it is of course a matter that requires serious thought.

However I would note that there have been naysayers from the day we climbed down from the trees. I am quite sure there were those who predicted doom for the Wright brothers, for Lindbergh, for the Apollo program, for the 747, for the A320, etc etc...
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
GolfOscarDelta
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 2:37 pm

Didn't Boeing already try this fly-by-wireless stuff for the 787 and then shelve it after they were unable to prove to the FAA that the wi-fi signals would be secure (un-hackable so to speak) ?

Also does anyone know if fly-by-light actually allows for weight savings as compared to fly-by-wire if so how much? because IMHO i think the difference b/w fly-by-wire and fly-by-light is basically changeing an electric current carrying wire to a light carrying fiber optic wire; where you are basically replacing one wire with another, so can you really achieve significant wieght reduction by using fly-by-light?
 
kalvado
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 2:40 pm



Quoting Starlionblue (Reply 2):
I am quite sure there were those who predicted doom for the Wright brothers, for Lindbergh, for the Apollo program,

I don't think it's a legitimate comparison - revolutionary change vs design rectification
First Wright plane broke after 4th flight; Apollo program took 3 lives in test stage and 3 more were on the edge..
Somehow I don't think anyone would pay for a jet which crashes "just" in 1 out of 10 flights.

Back to topic - from the link, it looks like they consider radio link benefits mainly for an uncontained engine failure scenario.. Maybe that's what it supposed to be - backup for the worst case scenario?
 
avt007
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 2:48 pm

I remember learning about wires in tech school back in 1986. After telling us what a wonderful thing Kapton was, he assured us that fibre optics would be replacing wiring in all new aircraft. 20 years later, all I've seen is the Dash 8-100 alternate nose gear indication, and all that is, is a light shining down a fibre optic tube, so you can see it in the flight deck!
I personally don't see any advantage to optics over wiring, especially since you can use data busses, and send lots of information over a single twisted pair. Assuming there is an advantage, it would be offset by repair costs. Anyone in the industry can repair a wiring harness, but what happens when your fibre optic cable gets damaged? As for wireless, again, is the weight gain offset by having a transmitter and receiver, and redundant components?
I'm all for advances, and new technology, but only if there's a clear advantage, not just high tech for high tech's sake.
 
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SEPilot
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 3:46 pm



Quoting Avt007 (Reply 5):
I'm all for advances, and new technology, but only if there's a clear advantage, not just high tech for high tech's sake.

 checkmark 
My primary concern would be interference. I suspect it will be very, very difficult to absolutely guarantee that it could not occur.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
Mir
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 4:20 pm



Quoting GolfOscarDelta (Reply 3):
Didn't Boeing already try this fly-by-wireless stuff for the 787 and then shelve it after they were unable to prove to the FAA that the wi-fi signals would be secure (un-hackable so to speak) ?

I believe so, but Gulfstream is very different from Boeing in one regard - it's customers are not afraid of paying top dollar for the fanciest toys. So while I have my doubts about getting it certified, if anyone can make it work, it would be them.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
avioniker
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 5:54 pm

The advantages to fiber optics are many. The fibers are a fraction of the weight of wire, signals travel truly at the speed of light, the databus language is not substantially different from ARINC wired standards, etc.

The single biggest downside is the fragile nature of the fibers. The aren't at all tolerant of excessive handling.
When a splice is needed the ends must be polished very precisely to prevent light (signal) loss and there is always some loss. Not to mention the lack of patience on the part of the tech who's trying to work in a very cramped environment at the end of a long shift. It's often easier to simply replace the bundle. (Glad those Gulfstream owners have throw-away money.)

What some believe the biggest hurdle to the use of fiber optics is the inherent vibration of all airframes and engines. It causes the phenomenon of micro-crazing. This is where the fibers develop microscopic cracks and crazing in the core of the fiber due to the vibration of the aircraft. Over time it causes loss of the light intensity until a point is reached where the fiber must be replaced. In multi-fiber bundles where the individual fibers aren't coated the crazing has the potential to cause cross fiber emission errors much like a short in a normal wire.

There's plenty of problems for the new crop of engineers to work out. I love listening to college professors and new engineers talking with stars in their eyes about fiber-optics and wi-fi. Especially when they start talking about the older workforce having to adapt to their new ideas. There's a reason for the skepticism on the part of the over 40 crowd; Experience.
Building something just to demonstrate that you can is never a good idea when put into mass production. Just one older workforce member's opinion, mind you. . .
 Smile
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
kalvado
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 9:39 pm



Quoting Avioniker (Reply 8):
The advantages to fiber optics are many. The fibers are a fraction of the weight of wire, signals travel truly at the speed of light, the databus language is not substantially different from ARINC wired standards, etc.

Well, if we're talking about high speed data transfer media (twisted pair or coax) both cable and fiber have similar propagation velocity, approximately 60% of speed of light. However, it would still take only few microseconds for the signal to travel across 747.

Quoting Avioniker (Reply 8):
The single biggest downside is the fragile nature of the fibers

I would say the biggest issue is inability to taper some signal from the media, and need for optics to electric converters at each point of use. Basically you cannot have an optical databus - you can have a point-to-point only.
Second best is temperature sensitivity of optics components. That's OK for indoor use, but temperature variations for airliner are too big..
 
CJAContinental
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 10:17 pm



Quoting Askr (Reply 1):
Is this stuff cheaper or lighter?



Quoting GolfOscarDelta (Reply 3):
Didn't Boeing already try this fly-by-wireless stuff for the 787 and then shelve it after they were unable to prove to the FAA that the wi-fi signals would be secure (un-hackable so to speak)

I thought that they abandoned it because they actually found that the aircraft could be lighter using wires. About potential hacking; didn't they find that because the three main computers, controlling flight entertainment systems, communication/CAS/navigation, and flight controls were interlinked, if someone were to hack into the computer through in-flight entertainment, they could then hack into the computer handling the flight controls?
Work Hard/Fly Right.
 
tdscanuck
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 10:28 pm



Quoting GolfOscarDelta (Reply 3):
Didn't Boeing already try this fly-by-wireless stuff for the 787 and then shelve it after they were unable to prove to the FAA that the wi-fi signals would be secure (un-hackable so to speak) ?

That was wireless IFE. As far as I know, they never tried fly-by-wireless.

Quoting GolfOscarDelta (Reply 3):
Also does anyone know if fly-by-light actually allows for weight savings as compared to fly-by-wire if so how much? because IMHO i think the difference b/w fly-by-wire and fly-by-light is basically changeing an electric current carrying wire to a light carrying fiber optic wire; where you are basically replacing one wire with another, so can you really achieve significant wieght reduction by using fly-by-light?

The wire itself is lighter (and smaller). On top of that, you don't need to shield it which, on FBW wiring, can be a big chunk of the weight of the bundle.

Tom.
 
LMP737
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 10:42 pm



Quoting Avt007 (Reply 5):
After telling us what a wonderful thing Kapton was, he

The synonym for Kapton is cheap junk.
Never take financial advice from co-workers.
 
askr
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 10:43 pm

Going back to the question of interference with Fly-by-WiFi (naturally not your household type :wink Smile - how can hey guarantee that some freak pax sitting next to a receiving node doesn't forget to switch off the wifi card of his laptop or something...
And those things can be quite power full - I've got a 150 mWat ERIP setup with my laptop for garden use... I know that the onboard stuff would probably run on different frequencies, but there is absolutely no assurance for something external blanking out the signal.

The onboard system might bidirectional, with the Tx resending commands if the Rx doesn't respond, but heck - thats a delay I would not like to encounter!

Using the Fly-by-WiFi system as an alternate, emergency system in case of, say an uncontained engine failure is a bit overkill for me, but plausible.
If the damage can take out control cables, than there is quite a big chance it will take out the hydraulic / electrical bus as well.
ATC-PL Wanabe :) - 2nd application is in... 11 July...
 
gigneil
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Mon May 26, 2008 11:07 pm



Quoting Kalvado (Reply 9):
I would say the biggest issue is inability to taper some signal from the media

I'm not sure what you mean by this. Optical networks can be tapped and split pretty easily for monitoring purposes. If you just mean kill relative transmit or receipt power, optical attenuators are easy and cheap ways to do it, and are pretty deterministic, and of course more sophisticated transceiver sets can change their transmit power.

Quoting Kalvado (Reply 9):
need for optics to electric converters at each point of use.

You'd need an optical transceiver on every device, which in this case would be integral.

Quoting Kalvado (Reply 9):
Basically you cannot have an optical databus - you can have a point-to-point only.

That's certainly not true. Passive optical networks are effectively optical buses today, and even simpler methodology for doing it would be a tapped optical bus. You transmit down the fiber and use a simple set of mirrors to split it off and replicate it. That technology is cheap.

Would you WANT to do it? No. The A380, 787, and A350 aren't even using electrical buses, they're using avionics switched full-duplex Ethernet.

Buses suck for the communication of volume information.

Quoting Kalvado (Reply 9):
That's OK for indoor use, but temperature variations for airliner are too big..

There are lots of optics available that can accommodate much wilder temperature variants than that.


My turn to say why not to do it: The cost of the glass itself is prohibitive, and the cost of maintaining it high. There's not enough benefit.

NS
 
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Starlionblue
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Tue May 27, 2008 12:23 am

With a powerful enough EM pulse you can fry any electronics, wired or non. So just because it's a wire doesn't mean it's invulnerable.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
brons2
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Tue May 27, 2008 2:22 am



Quoting Avt007 (Reply 5):
Anyone in the industry can repair a wiring harness, but what happens when your fibre optic cable gets damaged?

You splice it. It's not some black science, lots of techs are trained to splice fiber, at least in my industry.

That being said, on an airliner, it seems to be a solution in search of a problem. ARINC switched copper ethernet should work fine.
Firings, if well done, are good for employee morale.
 
LMP737
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Wed Jun 04, 2008 11:38 pm

Earlier models of the 777 use fiber optics to connect the Maintenance Access Terminal with the AIMS cabinets. Of course this is a non-critical system. It's interesting to note that 777 coming off the line now have an Ethernet connection for this instead of fiber optics. Don't know why they changed it, I'm way to low on the totem pole to know these sorts of things.  Smile

I'm in the Avioniker camp when it comes to fiber optics on a large scale. Sure it sounds neat but the real test as he says when it's 3:00AM and you have a tired/cranky tech working on it.
Never take financial advice from co-workers.
 
MD-90
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Thu Jun 05, 2008 4:16 am



Quoting Avioniker (Reply 8):
What some believe the biggest hurdle to the use of fiber optics is the inherent vibration of all airframes and engines. It causes the phenomenon of micro-crazing.

You know, I've always wondered why Cirrus uses fiber optic lights in its planes. The bulbs for the overhead reading lights are actually located in the tail and the light travels through fiber optic cables up to the top of the cabin. Granted, that's simply light, and not data, but I've always thought that was an interesting choice.
 
osiris30
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Thu Jun 05, 2008 5:08 am



Quoting GolfOscarDelta (Reply 3):
Didn't Boeing already try this fly-by-wireless stuff for the 787 and then shelve it after they were unable to prove to the FAA that the wi-fi signals would be secure (un-hackable so to speak) ?

No.. that was for the IFE system, not flight control surfaces, etc.

Quoting Mir (Reply 7):
I believe so, but Gulfstream is very different from Boeing in one regard - it's customers are not afraid of paying top dollar for the fanciest toys. So while I have my doubts about getting it certified, if anyone can make it work, it would be them.

I think many people here don't realize how resilient a wireless signal can be made to be, especially at those incredibly small ranges. And there are advantages in that there are no lines to severed in the event of a failure of any kind. Inspect is also a breeze and if something is faulty you don't have to rip out wires that run the length of the fusealge.

Quoting Avioniker (Reply 8):
The single biggest downside is the fragile nature of the fibers. The aren't at all tolerant of excessive handling.

Fibre is a LOT more resilient than alot of people realize. I work with a lot of fiber on a regular basis... provided you don't put a hard kink into it (thereby causing refraction to occur within the strand) the stuff is pretty damned tough (I've seen it walked on, support ethernet switches that slipped from a careless persons hands, etc. and been no worse for the wear (in any meaningful terms of loss))

Quoting Avioniker (Reply 8):
When a splice is needed the ends must be polished very precisely to prevent light (signal) loss and there is always some loss.

This is getting much easier with the tools of today. Modern splicers are miles better than they were just 10 years ago.. they are also not suitcase sized any more  Smile

Quoting Avioniker (Reply 8):
What some believe the biggest hurdle to the use of fiber optics is the inherent vibration of all airframes and engines. It causes the phenomenon of micro-crazing.

Interesting. Hadn't heard of that before. Having said that, it sure sounds like a materials problem and not something I would imagine can't be solved with the correct application of effort.

Quoting Askr (Reply 13):
I know that the onboard stuff would probably run on different frequencies, but there is absolutely no assurance for something external blanking out the signal.

Directionality of the signal/antenna can do a lot to cut down on unwanted interference. Wireless signals can be shaped and you can do some clever things to only listen to signal coming from a specific location.

Also guys, lets remember.. ok, we're worried about interference/jamming... well let's see.. first thing I do is move into a frequency that's not commonly used. That rules out accidental interference.. this leaves us with intentional sabotage... well let's look at that scenario:

In flight @ altitude and speed: VERY difficult to jam the signal of the aircraft from an external source. Let's assume no one on the aircraft (in this case a corporate jet) wants to kill themselves (if they did, again on a corporate jet, there would be MUCH easier ways to do it).

On the ground, during takeoff, landing, etc. (i.e. those times you'd be vulnerable to 'easy' external interference): You can simply safe guard the computers so that should coms be lost via the wireless link they perform in a safety mode.. for example the engines are commanded to max thrust, and flight control surfaces to a moderate 'nose up' position until coms are restored.

Finally you can frequency hop like crazy, across a very wide spectrum.. and you can do it intelligently so that the next hop is agreed to by both ends of the connection, via encrypted traffic.

At the end of the day, it's not *that* hard to make the system robust to the point where other methods of downing the aircraft become a bigger concern. Given the budget these guys are playing with, I'm sure I could make the wireless system secure and robust enough to make a shoulder launched missle an 'easier' option for brining down a bird with than wireless hacking.

Quoting Gigneil (Reply 14):
Buses suck for the communication of volume information.

Point of order: Depends on the information  Smile.. if the information needs to have multiple consumers then buses can be a great way to do it.

Quoting LMP737 (Reply 17):
Don't know why they changed it, I'm way to low on the totem pole to know these sorts of things.

Cost. Ethernet got faster and even cheaper. Just go see how cheaply you can get a gigabit ethernet switch at (insert local computer store here) now, as opposed to 20 years ago (when ethernet was limping along at 10megs for most folks, and 100megs for the VERY rich/stupid/heavy datacenters).

Quoting LMP737 (Reply 17):
Sure it sounds neat but the real test as he says when it's 3:00AM and you have a tired/cranky tech working on it.

Really it's not that big a deal to splice anymore.. honest to goodness.. the machines do ALOT of the work these days, and I'm sure they will keep getting better.
I don't care what you think of my opinion. It's my opinion, so have a nice day :)
 
LMP737
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Thu Jun 05, 2008 2:37 pm



Quoting Osiris30 (Reply 19):
Really it's not that big a deal to splice anymore.. honest to goodness.. the machines do ALOT of the work these days, and I'm sure they will keep getting better.

It's not the equipment I'm worried about. It's the guy working on the equipment who's manhandling the associated hookups. AA used to have fiber optic reading lights in first class on their 777's. They got rid of them because they were to much of a pain. I remember changing one and having it come apart of me.
Never take financial advice from co-workers.
 
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HAWK21M
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RE: Gulfstream Takes The Wire Out Of Fly-by-wire

Fri Jun 06, 2008 9:07 am

Reliability of this system will prove its effectiveness over time.
Currently there are too many doubts.
regds
MEL
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