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Super Heavy has splashed down in The Gulf of Mexico

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Re: Super Heavy has splashed down in The Gulf of Mexico

#241

Post by simiones »

_glass wrote: post #227
simiones wrote: post #173

Earlier quoted context omitted.

Columbus very very much didn't plan to die (though he very much would have if he didn't get lucky that there was a whole new continent there). His plan was to land in India, which he thought he would reach around the time he actually reached the new continent, because he had a completely wrong idea of how large the globe actually was (he alone had this wrong idea; the actual circumference of the globe was pretty well…

Yeah, but it's in your text/comment. The logical thing is that it makes 0 sense. Columbus to not take the real circumference makes 0 sense. Let's go to Mars, start a civilization there. It'll be a lot of change for us humans. And only if you live somewhere you can really solve problems. Maybe it's a good plan against a nuclear war, whatever.

Columbus was just wrong, he was not motivated by some higher goal.

And no, it's not a good plan against a nuclear war, Mars is far far far less hospitable than the Earth would be if we launched all of the nuclear weapons we have today. It's far more radioactive, dusty, cold, toxic, and everything.

Re: Super Heavy has splashed down in The Gulf of Mexico

#242

Post by garaetjjte »

notact wrote: post #217
pixl97 wrote: post #68

What the hell, half melted starship actually did the landing flip and hit the ocean slow!!! That was amazing!

Can someone explain why reentry must be so hellish? The energy gained during the rocket burn into orbit must be bled off during reentry, and that energy is enormous. However, why must reentry occur so quickly? It seems if the descent into the atmosphere was slower, the heat shield would be able to radiate the heat energy away more effectively, thus lowering skin temperatures, and significantly reducing the engineerin…

If you are coming at higher speed eg. from the moon, then it's possible to slow down to get reentry equivalent to low earth orbit one. But you can't really slow down much more because you would just plunge into atmosphere at steeper angle. Some vehicles utilize skip reentry trajectories, where it does high altitude pass through atmosphere and then goes in second time: https://en.wikipedia.org/wiki/Non-ballistic_atmospheric_entr...

Re: Super Heavy has splashed down in The Gulf of Mexico

#243

Post by xnx »

mlindner wrote: post #226
xnx wrote: post #155

Big respect to that camera lens cover. The drama of seeing the camera get obscured and then have the cover crack was peak.

Everyone said it cracked, but it didn't look like cracking to me. It looked like carbon vapor deposition/metal vapor deposition.

That's how it started, but there was a specific moment where it suddenly cracked. Further deposition and debris may have obscured that crack later.

Re: Super Heavy has splashed down in The Gulf of Mexico

#245

Post by mhandley »

tocs3 wrote: post #237
mhandley wrote: post #204

Earlier quoted context omitted.

The fact that it managed the flip and landing burn means the fuel tanks (i.e. most of the fuselage) must have suffered no burn-through, despite what happened to the front flap. They've obviously got some redesign needed on the thermal protection around the flap hinges, but broadly, the thermal protection system and aerodynamic control during reentry seem to have worked well enough. It's finally starting to feel like…

One of the NSF commentators commented the fuel for the landing burn comes from the header tanks (little extra tanks for this kind of thing). Still, I would think if one of the closed up sections had a hole that it would cause all sorts of other troubles.

Yes, that is correct - they need the header tanks to make sure that fuel is immediately available, not sloshing around the main tanks as the ship flips. Rockets really don't like sucking in vapour. I'm not sure if they're pressurized separately from the main tanks though - I would assume not, as that would be more complicated, but I could be completely wrong.

Re: Super Heavy has splashed down in The Gulf of Mexico

#246

Post by mannykannot »

GJim wrote: post #172
steve1977 wrote: post #80

Earlier quoted context omitted.

When I was young, there were no rocket landings.

My grandfather recalls (what he later found out to be) a rocket landing in London's east end during his youth. There were quite a lot of them at the time.

"Once the rockets are up, who cares where they come down? That's not my department" says Wernher von Braun.

- Tom Lehrer.

https://genius.com/Tom-lehrer-wernher-von-braun-lyrics

Re: Super Heavy has splashed down in The Gulf of Mexico

#247

Post by bagels »

notact wrote: post #217
pixl97 wrote: post #68

What the hell, half melted starship actually did the landing flip and hit the ocean slow!!! That was amazing!

Can someone explain why reentry must be so hellish? The energy gained during the rocket burn into orbit must be bled off during reentry, and that energy is enormous. However, why must reentry occur so quickly? It seems if the descent into the atmosphere was slower, the heat shield would be able to radiate the heat energy away more effectively, thus lowering skin temperatures, and significantly reducing the engineerin…

It would take a tremendous amount of fuel to do what you're imagining, probably to the point of making the craft impossible to build with current technology.

Your orbit would have to be high enough to do a burn to cancel your orbital velocity (lots of fuel), then you have to burn against gravity for a slow vertical descent (lots of fuel). The rocket equation says... you'll need a larger craft and more fuel to carry the extra fuel in to orbit. It gets pretty out of hand.

Instead of using fuel to slow down, spacecraft make a small burn to have the orbit intersect the atmosphere, and then use drag instead of fuel to slow down.

Re: Super Heavy has splashed down in The Gulf of Mexico

#248

Post by dirkc »

bradley13 wrote: post #244

I hope they have footage from ships. It would be great to see actual videos of the soft landings. One dumb question I have: There was no payload, and yet starship used essentially all of its fuel to achieve this trajectory. How does this compute?

I don't think they fueled it up all the way. But I do thing the booster and maybe also starship itself is a little heavier than they plan to have it at the end.

*update* if you check the video just before launch (39:54), you can see that the fuel bars for both the booster and the ship is not 100% full: https://twitter.com/i/broadcasts/1OwxWYzDXjWGQ

Re: Super Heavy has splashed down in The Gulf of Mexico

#249

Post by bagels »

tocs3 wrote: post #228
notact wrote: post #217

Earlier quoted context omitted.

Can someone explain why reentry must be so hellish? The energy gained during the rocket burn into orbit must be bled off during reentry, and that energy is enormous. However, why must reentry occur so quickly? It seems if the descent into the atmosphere was slower, the heat shield would be able to radiate the heat energy away more effectively, thus lowering skin temperatures, and significantly reducing the engineerin…

They use the atmosphere to help slow the ship down. It takes most of the tank of fuel to get up there and moving so fast. It would take most a tank to slow down. So, they would need about double the fuel plus some for landing. P.S. I have not done any of the math (I might be able to figure it out but it might take a week or two to figure it out). P.S.S : Maybe if they could refuel in space efficiently (asteroid minin…

Its more than double.

Re: Super Heavy has splashed down in The Gulf of Mexico

#250

Post by notact »

tocs3 wrote: post #228
notact wrote: post #217

Earlier quoted context omitted.

Can someone explain why reentry must be so hellish? The energy gained during the rocket burn into orbit must be bled off during reentry, and that energy is enormous. However, why must reentry occur so quickly? It seems if the descent into the atmosphere was slower, the heat shield would be able to radiate the heat energy away more effectively, thus lowering skin temperatures, and significantly reducing the engineerin…

They use the atmosphere to help slow the ship down. It takes most of the tank of fuel to get up there and moving so fast. It would take most a tank to slow down. So, they would need about double the fuel plus some for landing. P.S. I have not done any of the math (I might be able to figure it out but it might take a week or two to figure it out). P.S.S : Maybe if they could refuel in space efficiently (asteroid minin…

I understand the atmosphere is used to slow the vehicle - it's basically free brakes that you don't have to carry with you. I never suggested using rockets in reverse to slow the vehicle down. What I am asking is, instead of effectively standing on the breaks and generating enormous amounts of friction in a short period of time, why can't the vehicle ease onto the breaks and spread the friction out over time so it can be more safely dissipated (via a more shallow reentry angle).
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