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Rockets consume a lot of fuel and carry not eough payload. To reduce the fuel needed, why not send it in the mesosphere?

Imagine a big balloon, capable of carrying a small rocket to the mesosphere (or at least stratopause) where about 99.9% of the air is located under, so basically, its almost a vacuum.

We would drastically reduce air friction: the rocket would be smaller.

How big would the ballon need to be (we could reuse it)?

For 5 tons of payload, how much of liquid oxygen and liquid hydrogen would we need (as rocket fuel)? How about for 10 tons of payload?

Thank you for your help.

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  • $\begingroup$ Balloons just...float away you can't control their course. They make for excellent targets since they can't be stealth. $\endgroup$ Jun 30, 2018 at 16:22
  • $\begingroup$ Shouldn’t this question be on the space exploration stack exchange? $\endgroup$
    – thebigtine
    Jun 30, 2018 at 19:23
  • $\begingroup$ Any question that asks about "real world stuff" is fair game here on WB.SE in an effort to understand how such things might be applied to a fictional world. $\endgroup$
    – elemtilas
    Jun 30, 2018 at 19:30
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    $\begingroup$ @elemtilas That is false. All other question requirements must till be met. $\endgroup$
    – Aify
    Jun 30, 2018 at 20:11
  • $\begingroup$ Most of the energy is expended in accelerating the vehicle and payload to orbital velocity. Only a small part is expended pushing the rocket out of the atmosphere. So the answer is, there would be a little saving on fuel, but nothing to write home about. Full explanation in XKCD What-If #58. $\endgroup$
    – AlexP
    Jun 30, 2018 at 21:24

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Achieving orbit is much more about velocity (gaining 16,000+ mph) than about altitude.

For vertical-launch rockets, a higher launch platform will save a few seconds' drag. The extra complexity is generally not worthwhile.

Horizontal-launch rockets (like Pegasus) spend longer in the atmosphere, so reducing atmospheric drag is worthwhile. Instead of a stationary launch site, they get a small extra velocity boost from their launch aircraft...since velocity is still more important than altitude if you want to make orbit. Note that no current horizontal-launch systems can handle 5 tons of payload.

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Using a balloon to launch a rocket is already a thing. Especially interesting here will be the democratization & commercialization of launching micro a/o nano satellites from a relatively cheaper platform.

Article

Using a dirigible HAPS may also be a way to go, as you can control the platform's motions in the way you can't with a balloon. Plus the station can be manned & manoeuvred more easily.

WP article

The first such launch was 70 years ago:

Rockoon

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You could have a rail system thousands of miles long, or a giant cannon, lifted miles high above at least part of the atmosphere by countless thousands of giant balloons, to accelerate a rocket to a good fraction of orbital velocity. Then the rocket would have to provide the rest of the acceleration and also circularize the orbit at the right altitude.

Such a system would be very expensive and would probably need a very high volume of launches to be worthwhile.

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Such a balloon rocket launch pad would probably be a very worthwhile and cost-effective endeavor somewhere like Venus, with a far thicker and denser atmosphere and with extremely difficult surface conditions. On Earth, not so much.

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