SpaceX Discussion Thread

[cubinator 8,744]

What's the mass of a Raptor engine? I'm sure they're planning to be able to carry spare engines for astronauts to replace on Mars if needed.

[tater 28,108]

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

[RealKerbal3x 6,000]

Just now, tater said:

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

It's always 'aspirational', but regardless of whether that goal is technically achievable or not, the ambition of it is a big part of what keeps SpaceX moving so fast. 

8 minutes ago, cubinator said:

What's the mass of a Raptor engine? I'm sure they're planning to be able to carry spare engines for astronauts to replace on Mars if needed.

I doubt they'll bring entire spare engines along, many of the first Starships to land on Mars will probably stay there so they can just cannibalise components from them. 

[tater 28,108]

 

[cubinator 8,744]

3 minutes ago, RealKerbal3x said:

I doubt they'll bring entire spare engines along, many of the first Starships to land on Mars will probably stay there so they can just cannibalise components from them. 

Ooh, yes, that's a good idea too. I dunno, though, Starship is pretty big. They might be able to fit just one, like a spare tire in a car. I'm sure they'll at least have a small stack of extra heat tiles, in case they find some broken en route to Mars.

[RealKerbal3x 6,000]

1 minute ago, cubinator said:

Ooh, yes, that's a good idea too. I dunno, though, Starship is pretty big. They might be able to fit just one, like a spare tire in a car. I'm sure they'll at least have a small stack of extra heat tiles, in case they find some broken en route to Mars.

Good thing about the stainless steel construction is that they'll be able to cannibalise literally everything. Old ships could be cut up and the material used to construct and repair buildings and vehicles. Raptors could be removed and used as spares, as I already said. There would be plenty of intact heat tiles, and they might even be able to use the tank sections as propellant storage. 

[YNM 2,620]

46 minutes ago, RealKerbal3x said:

It's always 'aspirational', but regardless of whether that goal is technically achievable or not, the ambition of it is a big part of what keeps SpaceX moving so fast. 

They're also more than ready to embrace the failures, and in fact expects failures. Harder to swallow for governments when the opposition can throw "but the money !".

All I'm waiting for are just the free fireworks show, then after the show ends we'll have a new technology ready for use...

Edited January 15 by YNM

[Shpaget 2,128]

Even if "a few hours at most" is ElonTime^TM it's still at least an order of magnitude faster than I'd expect. I keep getting amazed by their pace.

[kerbiloid 11,562]

Just use the classic time translation.

https://coding.abel.nu/2012/06/programmer-time-translation-table/

P.S.
The "don't poke the bears" rule is actual, too. 
Every time somebody asks SpX about time, the time gets farther by two weeks.

Edited January 15 by kerbiloid

[eberkain 724]

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 647]

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 1,087]

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 6,000]

 

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 647]

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 282]

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 by Vanamonde

[RealKerbal3x 6,000]

 

[magnemoe 2,714]

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 5,086]

They should use attachment nodes

[RealKerbal3x 6,000]

This is an amazing render:

 

[mikegarrison 4,221]

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 11,562]

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

[TheDeamon 2]

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 28,108]

 

 

[RCgothic 2,511]

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 2,620]

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 ?