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-3 votes

Helium balloon as a rocket

Well there are a few methods of getting to space with a balloon rocket. If you wanted to build a big balloon and then release it will fly uncontrollably and will probably never reach space. If you ...
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5 votes

Helium balloon as a rocket

There are at least two serious issues: Ascending to high altitude is useful in reducing air resistance, but does very little to aid the required orbital velocity of around 7500m/s. Using the gas in a ...
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3 votes

Why doesn’t NASA build its rockets using graphene?

Just because a substance has impressive specific strength, doesn't mean it has all the properties needed to make it generally useful. Specific strength, the ratio of strength to weight, is a very ...
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5 votes

How does Spinlaunch manage the counterweight right after launch?

Following Christopher James Huff great comment, some heavy counterweight on a very short arm could roll inside a cage. When spinning up the whole thing is balanced, the counterweight spins and rolls ...
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1 vote

Can we use magnets to land a spaceship (Starship)?

We could, but we won't. Other ways are more effective and reliable. Magnets or electromagnets on the spacecraft add mass and complexity. Extra fuel to make a landing slower and more precise adds ...
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2 votes

Why doesn’t NASA build its rockets using graphene?

Because it is carbon with high reactivity. It burns at fairly low temperatures in the presence of oxygen: "Graphene combusts at 620 K." Supersonic skin would burn up. Descending through its ...
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29 votes

Why doesn’t NASA build its rockets using graphene?

Many processes being used to make graphene only yield small and irregularly shaped flakes with a lot of defects. The size of those flakes is barely enough to render them visible for the naked eye, and ...
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  • 523
39 votes

Why doesn’t NASA build its rockets using graphene?

Besides the fact BradV pointed out that we don't have the technology to do this yet, the fact is that graphene on a macroscopic scale would not perform as well as the numbers you cited suggest. All ...
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  • 6,903
64 votes

Why doesn’t NASA build its rockets using graphene?

The Technology Readiness Level (TRL) of graphene is at 2 or 3 as far as I can tell. And that is TRL as related to making very tiny stuff. Anything used to build a structure for aircraft or spacecraft ...
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  • 1,536
8 votes

How does Spinlaunch manage the counterweight right after launch?

Spinlaunch releases the counterweight at the same time as the vehicle. Their patent says: The launch vehicle 105 may be released from the launch vehicle tether... Simultaneously, the counterweight ...
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1 vote

Sharp nose or Blunt nose vehicle for higher reentry speeds?

I keep hearing about reentry vehicle having to be a blunt nose but this reentry glider has a sharp profile. This is because the vehicles have very different use cases. The HTV-2 is looking for a low ...
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0 votes

Would it be practical to catch a rocket's exhaust to reuse it as fuel?

The exhaust from a liquid-hydrogen liquid-oxygen rocket contains a great deal of unburnt hydrogen. The stochiometric mix is 8:1 by mass but such rockets run at closer to 5:1 for maximum specific ...
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3 votes

Would it be practical to catch a rocket's exhaust to reuse it as fuel?

No, it would not be practical to do that. It is theoretically possible to convert exhaust into fuel back again. I know rockets use different fuel/oxidizer compounds, like for example hydrazine and its ...
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  • 523
2 votes

Would it be practical to catch a rocket's exhaust to reuse it as fuel?

The original question referred to a scheme to "catch the fuel as you go" but did not state whether the line connecting a rocket image to a "colector" [sic] image indicated that two ...
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