totm nov 2023 SpaceX Discussion Thread

[sevenperforce]

2 minutes ago, ThatGuyWithALongUsername said:

Also, with the higher melting point of steel and the multiple bolts, it's entirely possible that even if a tile does get cracked in flight, it would stay bolted on and the stainless steel could take the heat.

I agree.

I understand where their resources are being placed, but it was annoying to not have better renders of some of the critical areas, like the heat shield. It wouldn't have been too hard to add a honeycomb texture. Also, I think Elon mentioned once before that with the properties of stainless, they might be able to get away with only putting heat shielding on the very hottest parts of the windward side, so it may not even be over 10,000 tiles. 

2 minutes ago, ThatGuyWithALongUsername said:

Also, willing to bet that there's some work being done towards making the inspection quicker- maybe even to the point of using fancy equipment to just do a "quick scan" of the entire heat shield, instead of manually inspecting every single tile up close, but I really, really don't know enough about how that might work- I'm just imagining that with all our computery advances since the 1980's, surely that could help speed it up somehow.

I thought there were 21,000 tiles on the Shuttle but I just saw another source that said over 31,000. I believe the majority had to be removed, inspected, and reaffixed every flight. These definitely would not need to be removed and might not even need to be inspected individually.

2 minutes ago, ThatGuyWithALongUsername said:

Also, some questions: Where are the header tanks? There's a window at the nosecone, but they aren't in the tanks?

And are the grid fins on the booster still made of solid cast Titanium? Because that's a lot of Titanium.

A lot of titanium, yes, but at least they don't have to do anything between flights.

I'm disappointed by the renders. I think a lot of these details (like where the header tanks are) just aren't there.

8 minutes ago, tater said:

The narrow stance freaks me out, frankly.

At least they appear to have abandoned the "land on launch clamps" nonsense.

The narrow stance for Superheavy isn't a problem, I don't think. With hot-gas thrusters both fore and aft (Falcon 9 has only forward cold-gas) and multiple gimbaled engines for landing, plus a LOT of aft weight (the legs, for example, will probably weigh more proportionally than on Falcon 9), I don't see any trouble landing Superheavy. 

Starship is a problem. With payload up top and fewer engines in the back and those ginormous fins and that narrow, narrow stance...egads. They definitely need hot gas thrusters for days. It's a very kerbal thing, of course: if you lack control at some critical flight envelope, just throw on some more Vernors and be done with it. 

Speaking of which, the "turn and burn" approach makes more sense. I appreciated that he explained that. The engines only gimbal to 15%, so the flip adds horizontal velocity, which must be canceled before landing. You could correct this by using the control surfaces to orient almost nose-down before initiating the flip but that would end up accelerating you toward the ground, which you also do not want. I think I have a better idea how to pull this off in KSP, too.

I am surprised they did not ever try a subscale demonstrator with SuperDracos or something.

[tater]

The header tanks in these prototypes are right up in the nose, but that's for simplicity, and these are throw away vehicles. I think they evolve to be inside the prop tanks.

9 minutes ago, sevenperforce said:

Starship is a problem. With payload up top and fewer engines in the back and those ginormous fins and that narrow, narrow stance...egads. They definitely need hot gas thrusters for days. It's a very kerbal thing, of course: if you lack control at some critical flight envelope, just throw on some more Vernors and be done with it. 

I'm thinking for landing anyplace unprepared. Engines will excavate rather a lot of regolith.

[sevenperforce]

Just now, tater said:

The header tanks in these prototypes are right up in the nose, but that's for simplicity, and these are throw away vehicles. I think they evolve to be inside the prop tanks.

He said they would do dewar tanks for orbital ops to prevent boiloff but those will presumably be separate from the hot-gas bottles.

2 minutes ago, tater said:

I'm thinking for landing anyplace unprepared. Engines will excavate rather a lot of regolith.

Those legs scare me for even earthbound concrete-pad landings, let alone lunar or interplanetary ops.

[ThatGuyWithALongUsername]

44 minutes ago, sevenperforce said:

I agree.

I understand where their resources are being placed, but it was annoying to not have better renders of some of the critical areas, like the heat shield. It wouldn't have been too hard to add a honeycomb texture.

...

I'm disappointed by the renders. I think a lot of these details (like where the header tanks are) just aren't there.

Look a bit closer- there is a honeycomb texture, at least on a couple of the renderings:

I think it's also fair enough to assume that there's enough detail on the heat shielding that this is how much shielding the ship is gonna have- no more, no less.

 

And personally, I was happy with the renders. No, they didn't answer all my burning technical questions, and that was disappointing. But they looked so darn cool! And you could, for the first time, unlike any previous renderings, compare them with an actual thing that was right there! To me, the whole presentation just screamed "yes, this is happening. We are doing this" and that was amazing. Mk1 makes for an amazing prop, I guess, even if it isn't finished or built the same way.

 

And yeah, legs are a bit worrisome. But if they land precisely enough I think it will be fine. They just... really have to choose their landing sites carefully, maybe. And build a proper concrete pad as soon as possible on any planetary body they happen to visit.

 

That being, said, those legs combined with that crazy flip definitely makes me think that at least Mk1 or Mk2... probably won't make it at one point.

Edited September 29, 2019 by ThatGuyWithALongUsername

[sevenperforce]

1 minute ago, ThatGuyWithALongUsername said:

Look a bit closer- there is a honeycomb texture, at least on a couple of the renderings...

I stand corrected. Didn't have a look at the high-res renders until now.

1 minute ago, ThatGuyWithALongUsername said:

I think it's also fair enough to assume that there's enough detail on the heat shielding that this is how much shielding the ship is gonna have- no more, no less.

That I'm not sure about. The possibility of using fewer tiles on the lower-temp areas is still decent.

1 minute ago, ThatGuyWithALongUsername said:

And personally, I was happy with the renders. No, they didn't answer all my burning technical questions, and that was disappointing. But they looked so darn cool! And you could, for the first time, unlike any previous renderings, compare them with an actual thing that was right there! To me, the whole presentation just screamed "yes, this is happening. We are doing this" and that was amazing. Mk1 makes for an amazing prop, I guess, even if it isn't finished or built the same way.

Maybe I was too hasty. It'as awesome to see and I'm glad. I just think that the renders show some lingering uncertainty, e.g., what the heck they're doing with the legs, and so forth.

A thought occurred to me...if the Starship did start to list on landing (at least on the leeward side), there could be a computer subroutine to immediately flap the wings back in that direction to catch it. I would have to do some math to see whether it could rest in that position or not. Might be just enough if the PDSes were used sacrificially.

Come to think of it, flapping them back could also help correct a windward list, by changing CoM.

[billkerbinsky]

2 hours ago, kerbiloid said:

Though, 100 persons require 20..30 toilet seats each with pipes and pumps.

Don't need anywhere that many.    US OSHA requires five toilets for an office with 81-110 workers.   Source: https://www.shrm.org/resourcesandtools/hr-topics/risk-management/pages/osha-restroom-rules.aspx

Fast attack submarine (with a crew of ~112) has six toilets, one urinal: https://www.quora.com/How-many-restrooms-are-on-a-fast-attack-submarine

[kerbiloid]

29 minutes ago, billkerbinsky said:

Don't need anywhere that many.    US OSHA requires five toilets for an office with 81-110 workers.   Source: https://www.shrm.org/resourcesandtools/hr-topics/risk-management/pages/osha-restroom-rules.aspx

Fast attack submarine (with a crew of ~112) has six toilets, one urinal: https://www.quora.com/How-many-restrooms-are-on-a-fast-attack-submarine

On the Earth, in normal gravity. Where they don't need to attach/detach and do other operations with hoses and packages, where peristalsis works normal way, where they have windows and a lot of air and water around.

Though, as 100 human crew was definitely ridiculous, a 20-30 crew needs less, probably four.
And a bathroom if they don't like to smell like a zoo. Iirc, up to 300 l of water per crewman was required in Mir to have a bath in zero-G. Earth hated it.

And as they can't take a lot of oxygen to breath, they must have a whole electrolytic system to reprocess the dirty water and urine into breathable air.
Iirc in Mir they were using up to 25 kg of expendables per human per day, depending on work, uncluding a whole set of single-use towels and a clothes pack per several days.

You can reprocess water, but all clothes and towels should be either taken from the Earth, or washed, or burnt and recycled into methane, what means even more water reprocessing.
And don't forget to have a backup facility, as the journey may last for three years, and any malfunction  is lethal.

So, I'm afraid that properly a 200 t payload craft is something for 4..6 crewmen to Mars if they like economic class.

Edited September 29, 2019 by kerbiloid

[tater]

 

15 minutes ago, kerbiloid said:

On the Earth, in normal gravity. Where they don't need to attach/detach and do other operations with hoses and packages, where peristalsis works normal way, where they have windows and a lot of air and water around.

Yep. the 100 people to Mars thing is goofy, I'll accept it when they make the TMI burn with 100 people aboard, not before .

[ThatGuyWithALongUsername]

Yeah, I think 20-30 at best to Mars is more realistic, but maybe we're talking about the 18m one. This tweet, for example, *does* say "ultimately." Even though it has a picture of the 9m Starship,, that may be what they mean.

Also, I've just realized... power generation hasn't been addressed all the way since the original 2016 ITS, as far as I know. What happened to the solar panels? Did they switch to fuel cells?

[kerbiloid]

Spoiler

38 minutes ago, ThatGuyWithALongUsername said:

power generation hasn't been addressed all the way since the original 2016 ITS, as far as I know. What happened to the solar panels? Did they switch to fuel cells?

 

[Treveli]

26 minutes ago, kerbiloid said:

  Reveal hidden contents

 

100 people on board, 12 crew, 88 'power plant technicians'.

[StrandedonEarth]

54 minutes ago, kerbiloid said:

  Reveal hidden contents

 

 

27 minutes ago, Treveli said:

100 people on board, 12 crew, 88 'power plant technicians'.

Where’s my like button, dammit. But yes, that’s an elegant way of using the energy spent on keeping fit, that would otherwise be wasted 

[KSK]

13 hours ago, Xd the great said:

His company has 5000 employees? so 250 people is working on starship.

Also, consider the fact that those aren't rockets, but water towers that looks like a rocket and flies like a rocket.

If it looks like a rocket and flies like a rocket - I'm calling it a rocket.

A rocket cunningly disguised as a water tower if you absolutely insist.

[sh1pman]

 

[kerbiloid]

Spoiler

1 hour ago, Treveli said:

12 crew

Including 6 to manage solar sails.

 

Edited September 29, 2019 by kerbiloid

[Brotoro]

I like that they are landing the Superheavy on a pad near the launch tower instead of that landing-on-the-launch-clamps stuff.

[RealKerbal3x]

5 minutes ago, Brotoro said:

I like that they are landing the Superheavy on a pad near the launch tower instead of that landing-on-the-launch-clamps stuff.

Much better, a slightly lower chance of destroying the pad in the event of a landing failure

[kerbiloid]

11 minutes ago, Brotoro said:

I like that they are landing the Superheavy on a pad near the launch tower instead of that landing-on-the-launch-clamps stuff.

A R-7-like launchpad with four clamps (the "tulip"). Used also as a landing pad.
When Starship is starting, the clamps get released and bend outside. When it lands back, they bend inside and fix it.

Spoiler

 

Edited September 29, 2019 by kerbiloid

[RealKerbal3x]

So, what’s happening over in Florida? I suppose the part of that team that went to give Mk1 an extra push have returned now, but we haven’t been hearing many updates.

[CatastrophicFailure]

Man, we really need that like button back. 

5 hours ago, sevenperforce said:

Welding on the 35,000 nuts will be a pain for sure, though.

Robots, yo.  

Repetitive, high-precision tasks like this have been the domain of robots for decades, now. And as you pointed out, the vast majority of those bolts will be more or less identical. Luckily for Musk, he’s a little familiar with the ins and outs of assembly automation, Starship won’t forever be built in a field, after all. 

I think they’re building an actual factory in Florida at the KSC.

6 hours ago, RealKerbal3x said:

They could sleep and eat in shifts, so that 50 people sleep while the other 50 are awake.

This is how they’ve done it on submarines for decades as well. Life support issues aside, we’ve got plenty of experience with cramming dozens of dedicated, highly trained people into steel tubes in extremely close quarters for months on end already. And bringing enough food for all of them. 100 at once, I dunno, but at least the new crop will get windows. 

This may be a reason for using Mars as a stopping off point to the outer solar system. Not to refuel the ship so much (tho it would need it) but to give the crew a few weeks of “shore leave.”

There won’t be a need for them to bring years of supplies with them to Mars, either, that will already be waiting for them. Possibly an entire semi-finished colony with functioning food production already started, again set up by robots sent on the first few unmanned Starships. 

 

Edited September 29, 2019 by CatastrophicFailure

[CatastrophicFailure]

14 minutes ago, RealKerbal3x said:

So, what’s happening over in Florida? I suppose the part of that team that went to give Mk1 an extra push have returned now, but we haven’t been hearing many updates.

Yeesh, give ‘em a break, it hasn’t even been a day, yet.  They’ve earned it. 

[magnemoe]

35 minutes ago, kerbiloid said:

A R-7-like launchpad with four clamps (the "tulip"). Used also as a landing pad.
When Starship is starting, the clamps get released and bend outside. When it lands back, they bend inside and fix it.

  Hide contents

 

This is still used to launch Soyuz and work nice for that, the strongpponts it the booster top connectors. It will not work for starship landing as you will have error in position in both directions, you will also have horizontal forces. 
Now having an movable platform might work but not sure its worth it. 

[tater]

https://amp.cnn.com/cnn/2019/09/29/business/elon-musk-spacex-mars-starship-cost/index.html

 

She quotes part of the Bridenstine tweet and asks him about it. He says “Did he say ‘commercial crew’ or ‘SLS’?”

[sevenperforce]

18 minutes ago, tater said:

https://amp.cnn.com/cnn/2019/09/29/business/elon-musk-spacex-mars-starship-cost/index.html

 

She quotes part of the Bridenstine tweet and asks him about it. He says “Did he say ‘commercial crew’ or ‘SLS’?”

That was hilarious.

 

[Josh IN SPACE]

Cool presentation, lots of good questions from the crowd. I'm glad they don't appear to be seeking a clamp landing. It's probably doable but not worth going for yet.

It's gonna be nuts to see that thing belly-flop. I wonder how it would feel to be in that thing when it does the rapid turn at the end of the fall before performing the controlled landing. Seems a bit jarring.