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# Sky Tube

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Jim is appalled by the research into vacuum tube trains currently being undertaken. Jim reckons that a little fan infront of a stream lined train will work just as well.

In any case Jim has decided to point these researchers in the right direction. The only free vacuum near the planet is at altitude.

Jim proposes a helium balloon whose outer surface forms a tube. Within this tube two solar powered vehicles (that can maintain an atmosphere) are placed. The tube is bouyed sufficiently to settle at 30km above the earth.

The accelerations of the two vehicles will always sum to zero to prevent motion of the tube.

The rest is just maths...

Jim reckons a mid point transfer between vehicles will offer an opportunity to stretch ones legs, partake in a beverage and take a photo or two...

Who is Jim?
 — pocmloc, Apr 14 2011

//stretch ones legs// Particularly if one steps across too slowly.
 — spidermother, Apr 14 2011

 Why helium ? it's expensive and hard to replace. If something happens 30km up it's not going to matter much if you're on fire as well.

 For that matter, why a vacuum ? ... ooooooooohhh

<competing Idea "Hydrogen Tunnel" posted>
 — FlyingToaster, Apr 15 2011

Ummm, if you have a tube that can support itself at altitude, and a vehicle that can (presumably) contain people and propel itself at altitude, why not just put the helium on the vehicle, and forget the tube?
Otherwise you're maintaining all that length of tube for no reason (ie: most of the tube doesn't have a vehicle in it, and provides little (from your description) advantage to the vehicle).

The tube, unable to support the overpressure created by a high-speed vehicle traveling along it, ruptures at its weakest point, the apex. Jim plummets 30 kilometers to his death.
 — Alterother, Apr 15 2011

 There is no over pressure ...

 --- the vehicle is outside the balloon --- the ballon is shaped like a tube

So Jim can be inside the tube but outside the balloon. (Potentially Jim could cycle along in his scuba gear.)

Why is Jim referring to himself in the third person?
 — doctorremulac3, May 18 2011

 /Why is Jim referring to himself in the third person?/

There are actually two dudes named Jim. Three if you count Jerome.
 — bungston, May 18 2011

There is only one dude named Jim. Everyone named Jim is really the same person. It's the most parsimonious explanation.
 — mouseposture, May 18 2011

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