totm nov 2023 SpaceX Discussion Thread

[JoeSchmuckatelli]

What link are you guys watching? 

[RealKerbal3x]

Just now, JoeSchmuckatelli said:

What link are you guys watching? 

NASASpaceflight for commentary as well as LabPadre Pad Cam for a closeup view.

[tater]

I have the labpadre launch pad cam since the one thing I never want to hear is idiots talking.

I'll switch to SpaceX once they're live.

No statement on the Starship page about a test today yet.

Did find this cool image on spacex.com though:

[Lewie]

I work tonight...

 Curse my schedule!! I’ve got a good feeling about SN15, she might be the one...really don’t want to miss it. 

[JcoolTheShipbuilder]

Sn 15 launch tonight?

[Flying dutchman]

Everyday astronaut stream says scrubbed

[JcoolTheShipbuilder]

Just now, Flying dutchman said:

Everyday astronaut stream says scrubbed

Awwwe

[RealKerbal3x]

8 minutes ago, Flying dutchman said:

Everyday astronaut stream says scrubbed

Yup, the road closure was cancelled.

 

[YNM]

I guess because the vehicle is by SpaceX, this stream is appropriate here : (EDIT : It was re-scheduled)

Spoiler

 

(stream always [slightly] better on the long-running link)

Edited May 1, 2021 by YNM

[tater]

SN16.

SN16 likely good to go by whenever SN15 meets whatever its fate is.

[SunlitZelkova]

15 hours ago, kerbiloid said:

Even in a sandbox?

A sandbox is self contained and is probably legally more like a building than the ground "outside" (the regular nature ground) so I don't think so lol.

[SpaceFace545]

So why does spacex build starship like that. Like seriously it's being built like a silo. Why don't they use actual rocket building or aerospace techniques such as using milled isogrid "skin" or better materials such as aluminum and titanium (steel is good but not the best). Now don't give me excuses like "steels cheaper" or "making a rocket like a grain silo is cheaper" and "its just a prototype". Money aside this is marketed as the most advanced spacecraft ever built yet my farmer cousin can make the same thing.  This sounds kinda harsh but just why build something the cheapest way possible?

[YNM]

Just now, SpaceFace545 said:

Why don't they use actual rocket building or aerospace techniques

Oh yeah, like the first powered aeroplane was made by a bicycle repair shop...

idk. If it works, it works. Their focus is using cheaper-grade (cheaper due to larger tolerance from a different grade, not inferior) material so they can test their methods of flying. Will they do this on the final product ? Who knows. If it works now, it probably works later. If it doesn't, then they've figured out things while doing it cheaply. It only makes sense to do proper prototyping where you care about them (shape, method of control, engines). But it makes little sense on the materials itself, really - you just need it to withstand the forces enough to carry the test out.

[RyanRising]

42 minutes ago, SpaceFace545 said:

So why does spacex build starship like that. Like seriously it's being built like a silo. Why don't they use actual rocket building or aerospace techniques such as using milled isogrid "skin" or better materials such as aluminum and titanium (steel is good but not the best). Now don't give me excuses like "steels cheaper" or "making a rocket like a grain silo is cheaper" and "its just a prototype". Money aside this is marketed as the most advanced spacecraft ever built yet my farmer cousin can make the same thing.  This sounds kinda harsh but just why build something the cheapest way possible?

"Cheaper" isn't an excuse, it's SpaceX's whole claim to fame. Doing it cheaper allows them to develop (and sell) the rocket without running out of money. If they run out of money while developing the rocket, you don't get to see that rocket fly.

[cubinator]

1 hour ago, SpaceFace545 said:

So why does spacex build starship like that. Like seriously it's being built like a silo. Why don't they use actual rocket building or aerospace techniques such as using milled isogrid "skin" or better materials such as aluminum and titanium (steel is good but not the best). Now don't give me excuses like "steels cheaper" or "making a rocket like a grain silo is cheaper" and "its just a prototype". Money aside this is marketed as the most advanced spacecraft ever built yet my farmer cousin can make the same thing.  This sounds kinda harsh but just why build something the cheapest way possible?

They say steel has really good thermal properties - it can stay strong through atmospheric reentry as well as handle the cryogenic fuels. It also happens to be cheap and easy to weld together like a grain silo.

[tater]

1 hour ago, SpaceFace545 said:

So why does spacex build starship like that. Like seriously it's being built like a silo. Why don't they use actual rocket building or aerospace techniques such as using milled isogrid "skin" or better materials such as aluminum and titanium (steel is good but not the best). Now don't give me excuses like "steels cheaper" or "making a rocket like a grain silo is cheaper" and "its just a prototype". Money aside this is marketed as the most advanced spacecraft ever built yet my farmer cousin can make the same thing.  This sounds kinda harsh but just why build something the cheapest way possible?

Why build anything more expensively than you need to? All that matters is what the specs are, if they can do the job, being 100X more expensive doesn't matter (unless you are bragging how expensive they are).

They are building their GSE tanks exactly the same way—and each one of those GSE tanks could be bought off the shelf for about a half a million $. That gives you a benchmark on how much cheaper. SLS tanks are arguably ~2 billion each (They got paid $6.7B for 3 tanks).  These are literally quite possibly 1000X cheaper.

If they were 10% cheaper, then yeah, the money aspect would not matter, and they might do better to reduce risk by using the slightly more expensive version. Ti would not be slightly more expensive. CFC was vastly more expensive, and required loads of tooling for any iterative changes as well.

The world is covered with pressure vessels designed to hold LOX/CH4/propane/etc. They are made to pretty demanding standards, and survive for decades sitting outside. Ships and submarines? Ditto. Aircraft are different, as they not only have to meet required specs, they also must be light. That's simply not true for this sort of rocket. the relative mass of the skin ends up being small.

If SS ends up at ~100t dry mass, and wet it is 1300t (1200 propellants), the dry mass ratio is 7.7%.

So how is your cousin doing with his billion dollar rocket business, BTW? If he can do it, why isn't he? Is he satisfied with the billions he already has? Does he hate money?

You always want to minimize cost to the extent you can. If it is a trade off, then you address that—where to spend money, where not to spend money. All products do this. There is an off the shelf 100TB SSD—do you have one? Why not, it's the most expensive and most capable, right? Because you don't need a 100TB drive.

 

11 minutes ago, cubinator said:

They say steel has really good thermal properties - it can stay strong through atmospheric reentry as well as handle the cryogenic fuels. It also happens to be cheap and easy to weld together like a grain silo.

And they are using robotic welding (and x-raying the welds) at this point. The first prototype was extremely rough, that is no longer true.

Spoiler

No robots in this rocket factory. Notice the dents as well... look familiar?

Back of the room you can see the outside light pouring in through the open door. Not hermetically sealed, either. San Diego can be humid as well (where the Atlas missile factory was).

 

Edited April 30, 2021 by tater

[RCgothic]

They don't machine aluminium alloy isogrids for the fun of it. It's a ridiculously expensive technique, it's just that acheiving the same result with welding on those materials is basically impossible, it's hard enough to get a decent friction stir in a barrel weld, let alone all those intricate details.

On the other hand stainless steel is comparatively not difficult to weld. There's no point isogridding if welded struts work just as well.

And the stainless steel is chosen over the more conventional aerospace materials because it can better withstand the heat of re-entry without excessive heat shield.

 

Edited May 1, 2021 by RCgothic

[magnemoe]

1 hour ago, RCgothic said:

They don't machine aluminium alloy isogrids for the fun of it. It's a ridiculously expensive technique, it's just that acheiving the same result with welding on those materials is basically impossible, it's hard enough to get a decent friction stir in a barrel weld, let alone all those intricate details.

On the other hand stainless steel is comparatively not difficult to weld. There's no point isogridding if welded struts work just as well.

And the stainless steel is chosen over the more conventional aerospace materials because it can better withstand the heat of re-entry without excessive heat shield.

 

This, note that SpaceX does not isogrind falcon 9, even if it makes more sense for an reusable launcher.  They think its too expensive. 
Its also no reason to make aluminum, composite or steel tanks in an clean room. Clean room are used for satellites with sensitive optic. 

[YNM]

7 hours ago, magnemoe said:

Note that SpaceX does not isogrind falcon 9, even if it makes more sense for an reusable launcher.  They think its too expensive. 

It does say that they're using Al-Li like many other aerospace manufacturers but that's interesting. I've always thought that the milling must be really expensive, and letting go of it must've been a pretty good way to push down cost.

[tater]

As expected the hop seems to be moved to Monday (the county likes the beach to be open on weekends for people).

[tater]

 

[Lukaszenko]

18 hours ago, SpaceFace545 said:

So why does spacex build starship like that. Like seriously it's being built like a silo. Why don't they use actual rocket building or aerospace techniques such as using milled isogrid "skin" or better materials such as aluminum and titanium (steel is good but not the best). Now don't give me excuses like "steels cheaper" or "making a rocket like a grain silo is cheaper" and "its just a prototype". Money aside this is marketed as the most advanced spacecraft ever built yet my farmer cousin can make the same thing.  This sounds kinda harsh but just why build something the cheapest way possible?

Agreed. They should definitely make it at least as Space Shuttle, or better yet SLS. But 10x more expensive, because advanced. Make it so so expensive so as to bankrupt entire nations before the tooling is delivered, because it's a rocket dammit!

And, every component should be designed to be one-time-use only, as a true rocket should be.

They should make the access road to the pad out of single-crystal inconel. Why? Because rocket.

And scrap it after one use as well, for good measure. 

Down with Gwyneth! Down with Musk! 

SpaceFace545 for president of SpaceX! 

[kerbiloid]

18 hours ago, SpaceFace545 said:

Money aside this is marketed as the most advanced spacecraft ever built yet my farmer cousin can make the same thing. 

And another one could stick tiles on it.

[KSK]

19 hours ago, SpaceFace545 said:

So why does spacex build starship like that. Like seriously it's being built like a silo. Why don't they use actual rocket building or aerospace techniques such as using milled isogrid "skin" or better materials such as aluminum and titanium (steel is good but not the best). Now don't give me excuses like "steels cheaper" or "making a rocket like a grain silo is cheaper" and "its just a prototype". Money aside this is marketed as the most advanced spacecraft ever built yet my farmer cousin can make the same thing.  This sounds kinda harsh but just why build something the cheapest way possible?

Did you see the first couple of Starship tanks? Great big carbon fibre things built on a seriously impressive piece of kit. Very high tech, very futuristic, very lightweight.

Turns out that stainless steel (or the particular grade of stainless steel that they're using) was the better material. The fact that's cheaper as well was more than likely a factor too but that decision to switch to stainless steel was an engineering decision.

[Elthy]

Why is everyone here so eager to reply to trolls? If he would realy want to know why Starship is build from steel he could search for that, e.g. "why starship steel" yields tons of articles on that topic.