Carbon nanotubes and fiber optics

[Modelworks]

I was reading about how hard it is to install fiber lines for data due to the expense of routing all the lines through neighborhoods, digging up streets, running it on poles, etc.

Could we construct towers about half as tall as cell towers , then connect them with fiber lines running inside a cable constructed of carbon nanotubes ?

It is stronger than steel, but lightweight . The towers could be placed a mile apart or more, depending on the location. Cables could carry much more fiber than what is usually buried.

Thoughts ?

 

[Cogman]

Fiber, no. Fiber degrades quite rapidly when exposed to any sunlight, so adding the casing and such on top will make it just as heavy / heavier then copper lines. Not to mention it is very brittle, so the wind blowing the line back and forth could easily cause a line to break and the signal quality to degrade. Not to mention the Fiber splicers would go on strike if they had to splice on a pole.

Underground is really the best place for fiber, It is shielded from all the elements, is hardly ever bent or moved, and is relatively easy access for the fiber splicers.

It is expensive, and time consuming (I buried fiber for a couple of years) and its a big country. Those are some things people seem to easily forget when they moan and complain about fiber not being to every home.

I should note that when I said it would be heavier then coper lines, what I meant is copper has a relatively light sheathing around it. Fiber on the other hand has a pretty heavy one to prevent it from bending. (Also, it is coiled in such a way that makes it a PITA to open up.)

 

[Eeezee]

Wouldn't that be even more expensive than just digging up streets? Carbon nanotubes aren't exactly cheap...

 

[OUCaptain]

Feasibility and cost aside, I think we can all agree the last thing any one wants is more towers and cables over head.

 

[Super Nade]

I'm not sure how you can use nanotubes as a waveguide over such long distances? Especially at 1550nm?

 

[OUCaptain]

Originally posted by: Super Nade
I'm not sure how you can use nanotubes as a waveguide over such long distances? Especially at 1550nm?

He's referring to the nano tube tech to provide a strong enough guy wire to support the fiber cable between towers. This would allow you to pull the cable tighter and therefore allow longer distance between towers.

 

[Modelworks]

Originally posted by: OUCaptain

Originally posted by: Super Nade
I'm not sure how you can use nanotubes as a waveguide over such long distances? Especially at 1550nm?

He's referring to the nano tube tech to provide a strong enough guy wire to support the fiber cable between towers. This would allow you to pull the cable tighter and therefore allow longer distance between towers.

Exactly.
I got to thinking about this after reading several papers about the space elevator concept.
If it has tensile strength enough to do something like that, then between towers shouldn't be hard.

 

[Super Nade]

Originally posted by: OUCaptain

Originally posted by: Super Nade
I'm not sure how you can use nanotubes as a waveguide over such long distances? Especially at 1550nm?

He's referring to the nano tube tech to provide a strong enough guy wire to support the fiber cable between towers. This would allow you to pull the cable tighter and therefore allow longer distance between towers.

The core of a single-mode fiber is between 1-10um, add a cladding to that and you have a very macroscopic entity. I'm not sure if a material made of carbon-nanotubes can be precisely grown over a large dimension to accommodate this? Fibers are sensitive to bending and having them swing around in the wind is probably not a good idea.

 

[Rubycon]

Guy wires actually support vertical structures and masts, etc. The reinforcing wires to support the weight of cables is generally called the messenger. It's a nifty idea however increasing the span also means the pull on each run becomes tremendous and the tower would have to be incredibly strong to support this weight. With the increased swept area with such a long span also introduces challenges to deal with from weather - the pull from heavy winds and ice loading would be tremendous!

 

[The Boston Dangler]

a span of 1 mile? wooooooo nelly!

with a span of 1 mile, you would need to hang it far higher than most transmission towers. the necessary sag (to allow for thermal expansion and contraction, among other things) would be rediculous. at that height, the whole thing would need to be lit for low flying aircraft, and you couldn't build anything anywhere near it.

messenger is load-bearing member of self-supported cable, and is bonded parallel to the outer jacket of the cable. in the cable business, it's used for subscriber drops (rg-6, rg-11) and short spans feeding a large building (no more than .500, or half-inch diameter) because it costs much less labor. the phone company occasionally uses self-supported twisted-pair trunks of about 3 inches in diameter. more common for large aerial cable, and all fiber, is the use of a braided steel cable called strand, usually 3/8 inch. the cable is attached by wrapping a pair of steel wires around it, called lashing. fiber is always hung this way to allow for de-lashing and repairs or modifications. the strand, and all associated hardware, can support a minimum of a 2000 pound load.

10 years in the industry has taught me underground cables are just as susceptible to damage as aerial.

 

[OUCaptain]

Originally posted by: Rubycon
Guy wires actually support vertical structures and masts, etc. The reinforcing wires to support the weight of cables is generally called the messenger. It's a nifty idea however increasing the span also means the pull on each run becomes tremendous and the tower would have to be incredibly strong to support this weight. With the increased swept area with such a long span also introduces challenges to deal with from weather - the pull from heavy winds and ice loading would be tremendous!

Messenger wire, thats it. I knew guy didn't sound right. Thanks.

As long as the towers are in a straight line, all the middle towers will only have a vertical load. The towers on the ends on the other hand will have a significant horizontal load as well as vertical.

The swinging shouldn't be a problem. Fiber can bend and flex way more than people give it credit. Besides, this wouldn't be the first time fiber has been used in an aerial situation. Just a larger scale. As long as the carbon nanotube super duper messenger wire can support the weight, it's doable. I just don't any more damn cables and towers in my town. We've got plenty as it is.

 

[Rubycon]

What about galloping? Wouldn't longer spans be prone to severe pulling?

galloping lines

 

[Super Nade]

Why go through all that trouble when laying cables underground is easier and cheaper?

 

[Rubycon]

Actually running underground is extremely expensive particularly in urban areas. They both have their pros and cons. UG is immune to most weather. Repairs are costly. In wide open areas it may actually (with data) be feasible to use optical transmission. (wireless)

 

[Gibsons]

Originally posted by: The Boston Dangler
snip
10 years in the industry has taught me underground cables are just as susceptible to damage as aerial.

This surprises me, what are the most common causes of damage to underground cables? Water seepage, some guy with a backhoe...?

 

[lxskllr]

Originally posted by: Gibsons

Originally posted by: The Boston Dangler
snip
10 years in the industry has taught me underground cables are just as susceptible to damage as aerial.

...some guy with a backhoe...?

That's my guess.

 

[The Boston Dangler]

Originally posted by: Gibsons

Originally posted by: The Boston Dangler
snip
10 years in the industry has taught me underground cables are just as susceptible to damage as aerial.

This surprises me, what are the most common causes of damage to underground cables? Water seepage, some guy with a backhoe...?

yep, happens all the time. there's animal damage, too. once, i found an underground steam leak had obliterated 6 inches of cable. it wasn't damaged, it was gone.

 

[Cogman]

Originally posted by: The Boston Dangler
a span of 1 mile? wooooooo nelly!

with a span of 1 mile, you would need to hang it far higher than most transmission towers. the necessary sag (to allow for thermal expansion and contraction, among other things) would be rediculous. at that height, the whole thing would need to be lit for low flying aircraft, and you couldn't build anything anywhere near it.

messenger is load-bearing member of self-supported cable, and is bonded parallel to the outer jacket of the cable. in the cable business, it's used for subscriber drops (rg-6, rg-11) and short spans feeding a large building (no more than .500, or half-inch diameter) because it costs much less labor. the phone company occasionally uses self-supported twisted-pair trunks of about 3 inches in diameter. more common for large aerial cable, and all fiber, is the use of a braided steel cable called strand, usually 3/8 inch. the cable is attached by wrapping a pair of steel wires around it, called lashing. fiber is always hung this way to allow for de-lashing and repairs or modifications. the strand, and all associated hardware, can support a minimum of a 2000 pound load.

10 years in the industry has taught me underground cables are just as susceptible to damage as aerial.

I don't know. Did you do fiber burying? When we did it we used a florescent orange conduit that was pretty dang tough. That, and we tried to keep it at least 4 ft deep. Sure, that doesn't stop some goon that wants to take a backhoe through and dig up stuff (without first finding out whats buried) but at very least it would keep the average joe from splitting the line with his shovel.

The company I worked for was mostly in a rural area, so that might be a factor, but as far as I've heard our lines haven't been cut too often. The lines that are cut are generally not the fiber lines, but the bare 25 pair lines that we do.