totm nov 2023 SpaceX Discussion Thread

[MKI]

6 minutes ago, mikegarrison said:

Developing technology that can be used on Mars? Fine. Actually designing your Earth LEO ships as Martian landers? Idiotic.

Thats "end-game" requirements. The first boss is "rapid economic reusability" with core architecture needing to take that "end-game" into account.

Its one thing to change the architecture to support more specific requirements, like a HLS variant, or P2P, or even the required tanker variant. Its another to get the thing flying economically, and quickly in the first place, which is more or less where the Shuttle failed as it had only 1 iteration.

Starship is going to need a lot of iterations to solve all the technical challenges that get presented over time.

 

So yea there could be changes required for down-mass, but that shouldn't require large architectural changes relative to whatever is needed to fly/reuse the thing economically.

[tater]

The downmass difference is not going to be huge I would think. The bulk of most mass to LEO is in fact propellant, even with SS. Actual payloads tend to be volume-limited.

The base mass of the vehicle with nominal landing props is huge, and even a bare crew vehicle will have the additional crew compartment mass all the time as part of the vehicle dry mass.

I think the original spec mentioned a much lower return mass to Earth from Mars (20t?). That was for a crew vehicle, so the dry crew compartment, plus any actual humans, plus the stuff they need to stay a live for X months (and maybe some kgs of rocks).

That seems unclear reading it. 20t in addition to empty dry mass.

100 people (LOL) would leave ~10t for consumables, so landing "cargo" would have most of that 10t gone (except the recycled water), so maybe 15t plus the rest of the vehicle?

[CatastrophicFailure]

1 hour ago, mikegarrison said:

I've said it before, but it's a ridiculous idea to use a Martian landing ship as an Earth LEO ferry. Horses for courses.

Developing technology that can be used on Mars? Fine. Actually designing your Earth LEO ships as Martian landers? Idiotic.

Welp, people smarter than you or me seem to think it's a good idea, and they're the ones putting money where the mouth is, so I'm gonna give them the benefit of the doubt for now. Most efficient way? No, probably not. Fastest, in terms of hardware development time vs same ol' same ol' that's gotten us nowhere? Now that might be something.

If it's stupid but it works... it's not stupid. 

[zolotiyeruki]

If you're returning stuff from orbit, it seems like you could ferry up a reentry capsule (a refurbished cargo dragon, perhaps?), stuff your spools of fiber optics in that, and deorbit/recover it in the traditional manner.

[mikegarrison]

28 minutes ago, CatastrophicFailure said:

Welp, people smarter than you or me seem to think it's a good idea, and they're the ones putting money where the mouth is, so I'm gonna give them the benefit of the doubt for now.

I know there are smarter people than me, because I've met some of them. But I'm not willing to randomly assume SpaceX engineers are among them.

[tater]

What downmass has SpaceX actually claimed for Cargo Starship? How would an uncrewed vehicle even secure any cargo?

The User Guide mentions point to point Earth cargo as a possibility, but gives no numbers at all. Other than that, no downmass is mentioned.

Downmass was suggested up thread as something that MIGHT be possible. The only statement actually by SpaceX I have ever heard are that as the User Guide suggests, P2P, but that's maybe not even the same exact vehicle , and the fact that a small payload can return to Earth from Mars.

I don't think it's being designed to bring payloads down from LEO at all, though it might have some capability in that regard assuming you could even secure the payload properly—which would be a pretty serious requirement otherwise a certain vehicle loss event would occur.

Lunar and Mars payloads are entirely different flight regimes, the first sorta easy (no atmosphere), and the second nearly no atmosphere.

Edited September 7, 2021 by tater

[tater]

 

[cubinator]

9 minutes ago, tater said:

 

That's a lot fewer tape strips on that thing.

[tater]

7 minutes ago, cubinator said:

That's a lot fewer tape strips on that thing.

I suppose they could have spent a few years modeling tile application, then tested in special (expensive) facilities, then come up with an approach to apply the tiles on their test vehicle perfectly the first time...

Or they could put 15,000 up over a couple weeks, figure out what didn't work, then fix it in a few more weeks, and next time get it much closer to perfect the first time.

If they end up with functionally tiled vehicles in less time than it would have taken to wait until they figured it out perfectly, this way wins.

Edited September 7, 2021 by tater

[NFUN]

What's the test schedule looking like?

[JoeSchmuckatelli]

1 hour ago, cubinator said:

That's a lot fewer tape strips on that thing.

It's almost like they want to fly it fairly soon 

[tater]

34 minutes ago, NFUN said:

What's the test schedule looking like?

Unsure, but both vehicles are now at the launch site.

There's some "mystery structure" that people assume is a thrust simulator for the booster, so perhaps they mess with that at some point? The might have moved B4 to the launch pad for more test fitting, since now they have GSE attachments they need to fit?

SN20 needs a static fire at some point.

[spacehex]

21 hours ago, sevenperforce said:

They’re not TUFROC but otherwise yes I agree. 

Oh right, I just assumed they were X-37B-esque TUFROC. Do you know what they are?

[sevenperforce]

56 minutes ago, spacehex said:

Oh right, I just assumed they were X-37B-esque TUFROC. Do you know what they are?

They are the same HFSI aerogel-esque silica-based ceramic that the Shuttle used, except thinner, tougher, and with a different waterproofing chemical.

Most importantly they are (mostly) mechanically-affixed rather than glued on, which solves most of the Shuttle tile problems. 

[derega16]

On 9/5/2021 at 7:50 PM, Minmus Taster said:

The tiles that have red tape on them are probably to indicate a tile needs to be replaced.

I meant one that pained red not tape

[Spacescifi]

1 hour ago, sevenperforce said:

They are the same HFSI aerogel-esque silica-based ceramic that the Shuttle used, except thinner, tougher, and with a different waterproofing chemical.

Most importantly they are (mostly) mechanically-affixed rather than glued on, which solves most of the Shuttle tile problems. 

 

While the Challenger disaster was tragic... at least sometimes the school of painful experiences forces mankind to refine technology so they don't die using it.

Several common things in use people died using in the begininng attempts

 

Aircraft. Submarines I think... X-rays... sure there are plenty more.

[JoeSchmuckatelli]

2 hours ago, sevenperforce said:

mechanically-affixed rather than glued on, which solves most of the Shuttle tile problems

We hope.

I'd hate to see a bunch shake off during the launch 

 

... of course the steel might just be good enough to make it if its only in a few spots.

[Silavite]

If nothing else, at least there will be no risk of foam insulation projectiles.

[tater]

36 minutes ago, JoeSchmuckatelli said:

We hope.

I'd hate to see a bunch shake off during the launch 

 

... of course the steel might just be good enough to make it if its only in a few spots.

Not sure what % of lost tiles were the result of vibration. We know TPS was catastrophically damaged by foam from the External Tank, however.

On the bright side, SS will not fly with people until that issue is sorted out, regardless. Either uncrewed vehicles fail reentry, or they land and any tile failures are examined and corrected until they land repeatedly without failures.

[cubinator]

9 hours ago, derega16 said:

I meant one that pained red not tape

The red stuff at the very tip is some glue, like what the Space Shuttle used.

[Beccab]

Lifting has begun!

[tater]

 

[MKI]

41 minutes ago, tater said:

 

The scale of this thing is just mind blowing. The people on the stand are still only the size of each engine bell... and the engines look tiny 

[mikegarrison]

It is very Kerbal, isn't it? Just a long cylinder with a few things tacked onto the side and then a bunch of engines spammed onto the bottom. All it needs now is moar boosters.

[MKI]

1 hour ago, mikegarrison said:

All it needs now is moar boosters.

I'd just think they part clipped all the boosters onto the bottom ;D