The Ultimate Arch

[webtaz99]

You first, dude. I'll hold the camera.<br /><br />"Here, hold my beer and watch <i>this</i>!"<br /> <div class="Discussion_UserSignature"> </div>

 

[vogon13]

You won't have to hold my beer . . . . <br /><br /><br /><br /><img src="/images/icons/rolleyes.gif" /><br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[nexium]

Humans have built taller stuctures most years for centuries. The end is not in sight. If we add one meter average per year: In 200,000 years we will be building 200 kilometer structures. With lots of funding and a few disassterous collapses, we can likely reach 12 kilometers by 2012. Predictions farther ahead are mostly wild guesses. The tallest structure in 2008 will be about one kilometer. Neil

 

[spacester]

The height of a vertical cylindrical tower is not limited by material properties, it's limited by Euler's Formula for Column Buckling. Google as desired. <div class="Discussion_UserSignature"> </div>

 

[nexium]

The height may be limited by the amount of high quality steel the world can produce. If the area of the base is a million times the area at the top of the tower (taper) static stress is a minor problem, even at a height of 200 kilometers. In this case windloading, thermal stress, foundation shifts, etc become the most challenging engineering problems. Neil

 

[kelvin_zero]

Why is the portion of an elevator in the atmosphere such a problem?<br /><br />There would still be great uses of a tower that could reach out of the atmosphere if it could be built. You could use a magnetic railgun approach like people have suggested for the moon.

 

[kelvin_zero]

and of course that is very easy since the ring is effectively a big circular mass driver. In fact accelerating the payload to orbital speed is actually deceleration to stationary wrt to the ring. Presumably it can then continue to accelerate the object the same velocity in the positive direction, releasing it with double the velocity at which the ring is orbiting. <br /><br />I actually came up with that idea independently (brag, brag <img src="/images/icons/wink.gif" /> ), but I didnt have the short elevator. Craft still had to make it up to the ring using beamed power. Each ring element was an independent satelite with a solar cell, laser to beam power, and ion drive to recover momentum and keep it aligned etc.

 

[nexium]

For the space elevator, www.liftport.com is thinking a very thin ribbon about a meter wide. The climber rollers will squeze the ribbon for traction, so changing to a round tether in Earth's atmosphere, complicates the climber design. Above the atmosphere, a round tether would soon be severed by micro meteorites and bits of space junk too small to track.<br />Also atomic oxygen in the upper atmosphere will quickly weaken CNT = carbon nano tubes because of the large surface area. Coating the very flat ribbon to protect it from atomic oxygen, may double the mass in the atmosphere. Most coatings will not stretch as well as CNT leading to coating failure. A reel of ribbon at the anchor ship may be 1000 kilometers long, all of which needs to be coated, in case it becomes desirable to unreel all of it temporarily. The hoytether is like a cylindrical fish net, so protecting it from atomic oxygen is also challanging. Neil

 

[kelvin_zero]

Couldnt get the link to work but thanks for that clear summary.<br /><br />Have they considered attaching to a high atmosphere balloon to allow a more robust cable for the last few kilometers? Ahh.. whom I kidding.. Of course someone has.

 

[publiusr]

Burj Dubai is closer to completion than I thought. This thing might be 3000 feet plus.