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Starship / Super Heavy

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Re: Starship / Super Heavy

#141

Post by blackrock »

What are the odds of Starship working? It seems really complex.

And that last phase where the ship flips vertical from the bellyflop, looks insane for human passengers inside. How many G’s is that maneuver pulling?

SN8 appears 90% successful, but I’m wondering if that remaining 10% is the killer.

As they say: You spend 10% of your time, solving 90% of your problem. And then you spend 90% of your time, solving the last 10% of your problem.

Between high speed re-entry, and thermal protections, I wonder how well the Starship design was modeled, to handle hypersonic re-entry speeds. It appears to be a very large spacecraft that’s re-entering the atmosphere at very high speeds.

If it succeeds, then maybe it’ll open up space travel and make it cheaper. If not, then well, nice try. Back to the drawing board.

But maybe, we’ll see results soon enough, with SN9.

Re: Starship / Super Heavy

#142

Post by savanaly »

dorkwood wrote: post #114
ubertoop wrote: post #72

Earlier quoted context omitted.

Nice use of "factoid". Most people use this world incorrectly.

If most people are using a word to mean something different, doesn't that mean the meaning of the word has changed?

If I choose to label them "incorrect" for their usage of "factoid", by your own argument I'm absolutely right.

Re: Starship / Super Heavy

#143

Post by edoceo »

sudosysgen wrote: post #136
adwn wrote: post #128

Earlier quoted context omitted.

> The Saturn V can carry those 3 people way further, though. Saturn V: 3 people to the Moon; Starship: 100 people to Mars (unproven, of course). Mars is a little further than the Moon. Granted, that's with in-orbit refueling.

The Saturn V would be three people to the moon and back. Starship is 100 people more or less around GTO. Multiple starships are needed to go to Mars. It's a pretty ridiculous comparison.

The Saturn V didn't come back with people did it? Just a small capsule splashing in the ocean

Re: Starship / Super Heavy

#144

Post by blackrock »

rtkwe wrote: post #67
TylerE wrote: post #58

Earlier quoted context omitted.

I guess the counterargument is that as long as you bring it down in a "safe" area, you don't really need a 100% success rate. If you can reuse it, great, if not, well, it's a rocket.

The belly flop is also how passenger variants will be landing so you do actually need a reliable program....

How many G’s will passenger experience when the ship transitions from the belly flop to the suicide burn?

That looks like an awful lot of G’s that this maneuver is pulling there.

Re: Starship / Super Heavy

#145

Post by perilunar »

mrlonglong wrote: post #21
colechristensen wrote: post #19

Earlier quoted context omitted.

The site has extensive solar power, I'm not aware of environmental concerns for solar-powered desalination. I would guess that it is driven by a real need for water and a hedge against environmental assessment difficulties.

What are they going to do with all the brine. It's quite toxic and I don't think it's a good idea to dump that back in the sea.

The discharge from the Sydney desalination plant has been unexpectedly good for sea life:

https://www.abc.net.au/news/2019-12-19/sydney-desalination-p...

Re: Starship / Super Heavy

#147

Post by chipsa »

trevyn wrote: post #44
wongarsu wrote: post #39

Earlier quoted context omitted.

When launching rockets on land you need flame diverter trenches to deal with exhaust and water deluge systems to deal with the sound (the water droplets absorb sound). When launching on water, dealing with the exhaust is more straightforward, but sound travels much better in water than in air, so it's a much bigger problem (mostly for marine life). One idea is to create a curtain made out of air bubbles that effectiv…

Wait, the water they spray on a land launch is only for sound suppression?

Mostly, yes. Some of it is used for protecting the structure (ablative armor, essentially). But that requires much less water than is actually used. This is why Sea Launch's launch platform also had a water deluge system. They're far enough out that the only people that can really hear it are the control ship, but they have the deluge to help keep the exhaust from scorching the launcher.

Similarly, the Saturn V MLP had "rainbirds" to wet it down, even though the vast majority of the water used was down the exhaust trench for sound suppression.

Re: Starship / Super Heavy

#148

Post by TeMPOraL »

sudosysgen wrote: post #136
adwn wrote: post #128

Earlier quoted context omitted.

> The Saturn V can carry those 3 people way further, though. Saturn V: 3 people to the Moon; Starship: 100 people to Mars (unproven, of course). Mars is a little further than the Moon. Granted, that's with in-orbit refueling.

The Saturn V would be three people to the moon and back. Starship is 100 people more or less around GTO. Multiple starships are needed to go to Mars. It's a pretty ridiculous comparison.

Getting to LEO is already halfway to anywhere in the Solar System, though. And then Starship can go back and land.

Re: Starship / Super Heavy

#149

Post by ggreer »

wongarsu wrote: post #51
trevyn wrote: post #44

Earlier quoted context omitted.

Wait, the water they spray on a land launch is only for sound suppression?

Yes. Without it large rockets like the space shuttle might create more than 200db at lift off, enough to kill someone or to damage the rocket https://en.wikipedia.org/wiki/Sound_suppression_system

If rocket damage is a concern, why don’t such rockets destroy themselves right after leaving the launchpad? At that point the water suppression is no longer relevant but the sound waves are just as powerful. It can’t just be that the ground reflects sound waves, since that would only be a ≈3dB (2x) increase in sound energy. Rockets with >2x more thrust seem to use the same sound suppression, so rocket damage can’t be the main reason for installing such systems.

My guess is that water systems are needed to reduce damage to the launch pad.

Re: Starship / Super Heavy

#150

Post by juanbyrge »

valuearb wrote: post #133
nerpderp82 wrote: post #113

Earlier quoted context omitted.

I prefer Mercury.

Ironically Mercury is definitely more inhabitable than Venus.

How so? The dark side of Mercury is frozen and Mercury rotates very slowly (one day on mercury is 2 months on earth). If you had a rolling home base you maybe able to avoid the extreme heat.
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