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How high can a balloon/s be and still be tethered to the ground? enter image description here

The most common problem was finding the calmest place on Earth.

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The longest balloon chain is 20 km

Pictures below are basic balloon chains.

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closed as off-topic by abelenky, Simon, Pondlife, Jay Carr, Federico Sep 2 '16 at 20:26

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about aviation, within the scope defined in the help center." – abelenky, Simon, Pondlife, Jay Carr, Federico
If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ if the question is about using balloons as a space elevator, this seems like a better fit for space.SE than here $\endgroup$ – Pondlife Sep 2 '16 at 19:04
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    $\begingroup$ @Pondlife but balloons are only going to be useful within the atmosphere, so that part seems on topic here. $\endgroup$ – fooot Sep 2 '16 at 19:26
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    $\begingroup$ @fooot I think you can see it either way, this just doesn't feel like aviation to me. But it's only my opinion and if someone has a good answer then that's great. $\endgroup$ – Pondlife Sep 2 '16 at 19:42
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    $\begingroup$ It's a physics problem (Archimedes' principle) more than a space exploration or aviation one. At some point a "lighter than air" is not lighter at all and its buoyancy can just balance its weight and the raise stops, exactly like a submarine can climb from depths, but cannot raise in the atmosphere. Unfortunately this point is not part of "space" (100 km altitude) as nothing is lighter than vacuum. Adding a rope will make the maximum altitude even lower. Very much lower. $\endgroup$ – mins Sep 2 '16 at 20:40
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As you go higher the pressure decreases which means that the density of both the air and the lifting gas goes down.

That means that the higher you want to go the bigger the balloon you need for a given lifting force. Eventually you reach a point where it is not not practical to make the structure light enough to go any higher. The highest altitude reached by a balloon is considerably lower than the lowest altitude at which orbit is practical.

It also means that as you go higher the wind-area of your balloon increases which will put more force on the tether. The loading from the tether, both from it's weight and from winds at various altitudes will further reduce the practical maximum altitude compared to a free floating balloon.

There is also the issue that in low orbit you need a considerable sideways movement relative to the ground. Most of the delta-v in a launch rocket is spent on gaining the sideways velocity, not in gaining the altitude.

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No, it would not work because there will be a point where the balloons will stop rising due to the fact that the density of the gas inside and outside are the same. In space, you have a near-vacuum which is lower than the density of the hydrogen inside the balloon which means that you cannot have a balloon floating in space.This short article talks about helium balloons, but the principles are the same (The numbers for hydrogen should be different though, but not by too much).

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