Are there theoretical and practical limits to reducing the size of a space rocket for launching into near-Earth orbit?

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rPman2016-03-06 01:28:51

Theory

rPman, 2016-03-06 01:28:51

Actually the whole question is in the title.
At the moment, spaceships are trying to make it as heavy as possible, since it is economically justified, and the tasks often lie in launching very large satellites or long distances into orbit (second space and interplanetary flights).
What about micro rockets? What can a rocket be like with a payload of 10 kilograms? Kilogram? Hundred grams? Smaller?
Let's omit the questions of the appropriateness of this from an organizational point of view, the question is only about the potential and the availability of the necessary technologies and materials.

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4 answer(s)

A

Alter2, 2016-04-16
@Alter2

This limit is determined by the Tsiolkovsky formula: https://ru.m.wikipedia.org/wiki/Formula_Tsiolkovsky
If the payload mass is reduced, the structural quality k begins to deteriorate sharply, because the fuel mass decreases in proportion to the volume - the cube of linear dimensions, and the structure mass - in proportion to the wall area, the square of linear dimensions. Roughly speaking, they reduced the size of the rocket three times, the mass of the fuel decreased by 27 times, and the mass of the structure by 9 times, the structural quality fell by a factor of three, and this is not even considering the fact that the engines are not so easy to scale, there are structural strength limits. In general, everything depends on the specific impulse and existing materials. The appearance of suitable structural materials makes mini-rockets unnecessary: it is already possible to build a space elevator.

A

Alexey S., 2016-03-06
@Winsik

the bulk of the rocket is fuel, until the engines are radically changed, the mass will change little.

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mamkaololosha, 2016-03-06
@mamkaololosha

If a rocket weighs a ton, then it doesn't care about these grams of yours.
I propose to parse this and ban the authors.

I

IvanKkhakhalin, 2016-03-26
@IvanKkhakhalin

A rocket capable of entering orbit must have a certain ratio of fuel mass to its own mass. If my memory serves me right, for modern rockets this ratio is the same as the ratio of the mass of cola to the sum of the mass of cola and the aluminum can in which it is located.