totm nov 2023 SpaceX Discussion Thread

[eberkain]

I realize its a testing program, but it seens like every engine test reveals engine issues.  At what point do we start to consider that using the most complicated rocket engine ever built for starship might not have been the right move.  

I am a huge SpaceX fan, but i really worry how they are going to get super heavy to work with so many engines. 

[JoeSchmuckatelli]

1 hour ago, Shpaget said:

 it's still at least an order of magnitude faster than I'd expect. I keep getting amazed by their pace.

I am too - but you have to admit; it's a heck of a lot cheaper to test prototypes with just computers aboard than people.  Also,

• if Elon&Co crash a rocket, everyone says, "Aww, that's too bad.  Better luck next time."
• if NASA crashes a rocket, Congress and the Press start the whine about 'waste of money.  Where was the oversight!  Need moar administrators, and lets slow this thing down until after a full investigation, review and wait for the next Administration's funding cycle"

[Clamp-o-Tron]

7 minutes ago, JoeSchmuckatelli said:

I am too - but you have to admit; it's a heck of a lot cheaper to test prototypes with just computers aboard than people.  Also,

• if Elon&Co crash a rocket, everyone says, "Aww, that's too bad.  Better luck next time."
• if NASA crashes a rocket, Congress and the Press start the whine about 'waste of money.  Where was the oversight!  Need moar administrators, and lets slow this thing down until after a full investigation, review and wait for the next Administration's funding cycle"

This- also, NASA doesn't really do rapid prototyping for that reason. SpaceX can waste hardware as it was never really meant to fly missions. SN8 was never meant to carry out a serious orbital flight, so its destruction wasn't an impediment to the development program. However, if the Artemis-1 core stage RUDs tomorrow, that will be CATASTROPHIC because there won't be an Artemis-1, and the test stand at Stennis will be destroyed.

[RealKerbal3x]

 

37 minutes ago, eberkain said:

I realize its a testing program, but it seens like every engine test reveals engine issues.  At what point do we start to consider that using the most complicated rocket engine ever built for starship might not have been the right move.  

I am a huge SpaceX fan, but i really worry how they are going to get super heavy to work with so many engines. 

Both Starship and Raptor are in a comparatively early stage of development at the moment. There are going to be issues, and as you said it's a testing program and the purpose of a testing program is to find issues and fix them. I'm sure Merlin had just as many teething issues during its development, and look at it now - one of the most reliable rocket motors in the world. 

And it's an engine designed for a groundbreaking superheavy lift fully reusable rocket intended to make humans a multiplanetary species. I'm sure during its development they made every effort to reduce complexity, but it's always going to be complicated.

[JoeSchmuckatelli]

16 minutes ago, Clamp-o-Tron said:

This- also, NASA doesn't really do rapid prototyping for that reason. SpaceX can waste hardware as it was never really meant to fly missions. SN8 was never meant to carry out a serious orbital flight, so its destruction wasn't an impediment to the development program. However, if the Artemis-1 core stage RUDs tomorrow, that will be CATASTROPHIC because there won't be an Artemis-1, and the test stand at Stennis will be destroyed.

I don't disagree - but what we are seeing here is the value of pushing through; they have a very, very different mindset from the US Governmental 'Zero Defect Policy' thing that affects many departments so adversely. 

 

(Saw this in the Marines, and hated it greatly, during the Pre-Iraq War days... It went away when necessity put theory to the test in '03-05 -- but over time, it has settled its innovation smothering blanket back over everything.  NASA has suffered this since the Moon landings - with a possible exception of the early days of Shuttle.

 

Fact is - when you accept that there is value to learning through failure, you can achieve success so much faster.  It's when you FEAR criticism and will only accept perfect execution that things get very expensive and take for ever (if ever) to be accomplished.

[Meecrob]

23 hours ago, eberkain said:

I realize its a testing program, but it seens like every engine test reveals engine issues.  At what point do we start to consider that using the most complicated rocket engine ever built for starship might not have been the right move.  

I am a huge SpaceX fan, but i really worry how they are going to get super heavy to work with so many engines. 

Given how advanced the Raptor is, I would call [nonsense] if they didn't have any issues during development. It also seems the issues cropping up have not led to any major re-designs, which is very promising.

Edited January 16, 2021 by Vanamonde

[RealKerbal3x]

 

[magnemoe]

On 1/15/2021 at 4:31 PM, tater said:

"Needs to be a few hours at most." is "aspirational" I assume.

The engine is a unit who is installed. You can design them to be faster to swap out. 
And it make sense making it an line unit who is designed to be swapped if something is wrong. rather than trying to fix it then installed.

[Deddly]

They should use attachment nodes

[RealKerbal3x]

This is an amazing render:

 

[mikegarrison]

7 hours ago, magnemoe said:

The engine is a unit who is installed. You can design them to be faster to swap out. 
And it make sense making it an line unit who is designed to be swapped if something is wrong. rather than trying to fix it then installed.

Like on airplanes, I would expect that some maintenance of the engines would take place on-wing (as we call it), while other maintenance would be done by swapping out the engine. An engine swap can generally be completed in a shift (i.e. less than eight hours). So "a few hours" for an engine swap is a reasonable goal if he really wants to aim for airline-like turnaround times.

[kerbiloid]

They should add a swappable propulsioon unit to swap the whole engine assembly between flights.

[TheDeamon]

On 1/15/2021 at 1:35 PM, Clamp-o-Tron said:

This- also, NASA doesn't really do rapid prototyping for that reason. SpaceX can waste hardware as it was never really meant to fly missions. SN8 was never meant to carry out a serious orbital flight, so its destruction wasn't an impediment to the development program. However, if the Artemis-1 core stage RUDs tomorrow, that will be CATASTROPHIC because there won't be an Artemis-1, and the test stand at Stennis will be destroyed.

It isn't just NASA with that problem. Boeing couldn't do that either government contract or no. Their shareholders would be filing SEC complaints.

[tater]

 

 

[RCgothic]

2 minutes ago, YNM said:

Again, I'm not sure how you'd refit a Starship to receive something else on top of it, given the header tanks and whatnot. What you're asking is like taking the TKS spacecraft and adding a capsule on it when it already have one. And again this is not the Starship design-related thread.

Well I mean if (and if) NASA contracts the Starship as a moon lander, then they'd already be man-rated, at least in space. OFC you can't launch it on itself from the Earth without sacrificing all the payload and the fuel, so in effect it needs the first stage, which is real early in development. That's the one I'm questioning would be man-rated by mid 2020s. But to my understanding they're aiming for man-rating.

Also, NASA might be more open for reused boosters than you might think, given that they're still considering to allow F9 reused booster for Commercial Crew. (although we haven't seen one being manifested so perhaps after two or three years...)

They wouldn't need header tanks on an expendable starship because it's not landing anywhere. They're pretty easy to leave out.

Expendable Starship has already been mooted, and for Orion it'd be even easier because no fairing is required, just a stage to spacecraft adaptor which is not difficult to make from stainless steel.

[YNM]

1 hour ago, RCgothic said:

They wouldn't need header tanks on an expendable starship because it's not landing anywhere. They're pretty easy to leave out.

Expendable Starship has already been mooted, and for Orion it'd be even easier because no fairing is required, just a stage to spacecraft adaptor which is not difficult to make from stainless steel.

Starship is supposed to carry passengers anyway, they'll have a pressurized section...

Also, the standard version will have that flap and stuff. I honestly don't see how they're going to put a version that'll have a separable fairing - not that they can't do it but it makes little sense for them to ever put such version.

Like... what you're proposing is Dragon V1 trunk but with Starliner or Orion capsule. Why'd you want that ?

[RCgothic]

1 hour ago, YNM said:

Starship is supposed to carry passengers anyway, they'll have a pressurized section...

Also, the standard version will have that flap and stuff. I honestly don't see how they're going to put a version that'll have a separable fairing - not that they can't do it but it makes little sense for them to ever put such version.

Like... what you're proposing is Dragon V1 trunk but with Starliner or Orion capsule. Why'd you want that ?

Crew Starship can't go to TLI without refuelling, and there's a large obstacle to crew rating it. It's a long pole.

Capsule on top of an expendable starship is the easiest and fastest way to put crew on it, and it keeps Orion and the Artemis archeture basically as-is without starting again from scratch. 

[JoeSchmuckatelli]

1 hour ago, RCgothic said:

an expendable starship is the easiest and fastest way to put crew on it

...isn't the whole point of Starship to quit expending expensive rockets?

[Xd the great]

14 minutes ago, JoeSchmuckatelli said:

...isn't the whole point of Starship to quit expending expensive rockets?

Yes, eventually.

Problem is getting starship to launch humans directly without LES require an insane number of testing.

[tater]

 

[JoeSchmuckatelli]

2 hours ago, Xd the great said:

Yes, eventually.

Problem is getting starship to launch humans directly without LES require an insane number of testing.

I get that - but if Elon is dedicatedly focused on Mars; don't you think he's got to at least land and return SShip from the Moon... at least once?

 

That would be an enormous coup; especially if he brings back regolith... and then relaunches the same ship within a year

Edited January 18, 2021 by JoeSchmuckatelli

[mikegarrison]

7 hours ago, YNM said:

Starship is supposed to carry passengers anyway, they'll have a pressurized section...

Yes -- "supposed to". They are a long way from doing that.

They do have a few parts of the puzzle. They now have a crewed space capsule, so they know how to do that. And they have a crew-rated rocket, so they know how to do that.

But they have still never crew-rated a propulsive landing system. With a crew-rated Starship they would need for the ship to be considered safe enough to be its own escape system from a failed booster. (That was always pretty iffy for Shuttle/SLS.) A bigger hurdle is that Starship has absolutely no backup for propulsive landing. That has to work or everybody on-board is dead. That's a big, big hurdle.

And of course there is the whole issue that so far the only "Starships" that have actually flown have been nothing but flying fuel tanks, and the only attempt so far to make a high speed propulsive landing failed to land safely.

Edited January 18, 2021 by mikegarrison

[YNM]

8 hours ago, RCgothic said:

Crew Starship can't go to TLI without refuelling, and there's a large obstacle to crew rating it. It's a long pole.

Capsule on top of an expendable starship is the easiest and fastest way to put crew on it, and it keeps Orion and the Artemis archeture basically as-is without starting again from scratch. 

7 hours ago, Xd the great said:

Yes, eventually.

Problem is getting starship to launch humans directly without LES require an insane number of testing.

*looks at Shuttle where it's literally death if anything goes wrong while the SRBs are on, yet the first flight was immediately manned*

 

2 hours ago, mikegarrison said:

Yes -- "supposed to". They are a long way from doing that.

They do have a few parts of the puzzle. They now have a crewed space capsule, so they know how to do that. And they have a crew-rated rocket, so they know how to do that.

But they have still never crew-rated a propulsive landing system. With a crew-rated Starship they would need for the ship to be considered safe enough to be its own escape system from a failed booster. (That was always pretty iffy for Shuttle/SLS.) A bigger hurdle is that Starship has absolutely no backup for propulsive landing. That has to work or everybody on-board is dead. That's a big, big hurdle.

And of course there is the whole issue that so far the only "Starships" that have actually flown have been nothing but flying fuel tanks, and the only attempt so far to make a high speed propulsive landing failed to land safely.

Soyuz capsules have landing SRBs on them.

Also, they are now being contracted to investigate Starship as lunar HLS solution. That means that in a way they're providing for man-rating the thing, at least solely for in-orbit operations.

 

I'm not saying that man-rating this thing for launch and land on Earth will be easy. But we still have a decade in front of us. Let's not forget that F9 first flew in 2010, and they were only man-rated in 2020 after a whole decade of unmanned use. There's still time to 2030s. They'll just have to prove themselves with the unmanned version.

I'm not believing in Promised Elon Time folks. I only believe in Proven Elon Time, and we have that for F9/Dragon.

Edited January 18, 2021 by YNM

[mikegarrison]

3 minutes ago, YNM said:

Soyuz capsules have landing SRBs on them.

Several capsules intended for ground parachute landings use either airbags (Boeing Starliner) or SRBs (Soyuz, New Shepard, presumably the Chines Soyuz clone) to cushion the landing forces, but this is not the same thing as a propulsive landing. Those capsules will land survivably without that -- but there may be more force than desired upon impact.

8 minutes ago, YNM said:

Also, they are now being contracted to investigate Starship as lunar HLS solution.

There's no other choice on the moon.

[YNM]

2 minutes ago, mikegarrison said:

Several capsules intended for ground parachute landings use either airbags (Boeing Starliner) or SRBs (Soyuz, New Shepard, presumably the Chines Soyuz clone) to cushion the landing forces, but this is not the same thing as a propulsive landing. Those capsules will land survivably without that -- but there may be more force than desired upon impact.

Yeah, but the idea is there, you can turn spine-crushing landing into less-than-spine-crushing-but-still-awful landing.

2 minutes ago, mikegarrison said:

There's no other choice on the moon.

And it'll help their progress.

Edited January 18, 2021 by YNM