totm nov 2023 SpaceX Discussion Thread

[mikegarrison]

On 11/20/2019 at 3:52 PM, mikegarrison said:

With actual water tanks, and a lot of other pressure vessels, it's pretty standard to use a criterion known as "leak before burst". I wonder if SpaceX explicitly considered that? (Of course, they may have, and this was just an unexpected failure mode.)

https://en.wikipedia.org/wiki/Pressure_vessel#Leak_before_burst

 

22 minutes ago, tater said:

 

 

[CatastrophicFailure]

30 minutes ago, StrandedonEarth said:

So, @CatastrophicFailure, maybe you want to switch to 304L stainless? Or do you prefer the 301 results?

erm, what?

[tater]

@mikegarrison in this case, they strength of the material is improved via the cold temp, so they'd need to put cryos in it first anyway, or the test wouldn't tell them what they need to know (how it behaves in that temp regime).

This test was with nitrogen, so it's not like a LOX/CH₄ test at least (explosion risk wise).

[CatastrophicFailure]

Slightly better view of the leak here...

 

[StrandedonEarth]

22 minutes ago, CatastrophicFailure said:

 

erm, what?

Well, those pop tests end with a catastrophic failure when the tanks were built with 301 stainless. But with the 304L stainless it simply starting leaking, instead of a massive catastrophic burst rupture.

[mikegarrison]

1 minute ago, StrandedonEarth said:

Well, those pop tests end with a catastrophic failure when the tanks were built with 301 stainless. But with the 304L stainless it simply starting leaking, instead of a massive catastrophic burst rupture.

... Which might be because of the material, or because of the construction, or both.

[tater]

Both were destructive tests by intent.

The small test tanks are also different than full tanks, they are testing the material, and the technique.

[CatastrophicFailure]

41 minutes ago, StrandedonEarth said:

Well, those pop tests end with a catastrophic failure when the tanks were built with 301 stainless. But with the 304L stainless it simply starting leaking, instead of a massive catastrophic burst rupture.

Eh, small beans. I'm waiting for that inevitable catastrophic failure when a full-sized SSSN (not to be confused with SSN) bellyflops into the ocean from 20 klicks. 

[sh1pman]

22 minutes ago, CatastrophicFailure said:

Eh, small beans. I'm waiting for that inevitable catastrophic failure when a full-sized SSSN (not to be confused with SSN) bellyflops into the ocean from 20 klicks. 

The tanks will be mostly drained and full of gaseous CH4 and O2. Oh yeah.

https://en.m.wikipedia.org/wiki/Thermobaric_weapon

[CatastrophicFailure]

Then again, I suppose seeing an SSN fall from that height would be pretty spectacular too... for entirely different reasons... 

[CatastrophicFailure]

closeup of the poof. 
Question now is, do they move on, or shall this tank be...un-poofed...
pokes @Just Jim with a stick 

[tater]

1 hour ago, CatastrophicFailure said:

Question now is, do they move on, or shall this tank be...un-poofed...

Musk said before the test they knew it had a problem which was already addressed for a follow on test tank.

[kerbiloid]

The hopper-flopper has appeared to be a hopper-popper.

Couldn't they finally hire a reservoir engineer? The humanity has a long history of chemical and gas plants.

12 hours ago, tater said:

Tank is almost totally white now.

As they definitely know about albedo and can calculate heat income before painting, they obviously don't just pick random colors from a shop, but do some serious magic.

[micha]

22 minutes ago, kerbiloid said:

Couldn't they finally hire a reservoir engineer? The humanity has a long history of chemical and gas plants.

The trick, I'm guessing, is volume-to-weight ratio.

It's "easy" to make strong enough tanks, as you said, humanity has some experience with that by now.

[Ultimate Steve]

"Any idiot can build a bridge that stands, but it takes an engineer to build a bridge that barely stands."

[magnemoe]

16 hours ago, tater said:

Cool render:

 

They will need another way to deploy them however. 

I'm I the only one who don't like the whale mouth door? Yes its probably the lightest solution.
As I see it it has some problems. first is obviously payload integration. 

The second is satellite deployment, as I understand satellites will be put into its own container. For something like starlink you will have stacks inside the container. who will then be placed in the bay, assume they will use some sort of framework if they have many containers. 
Benefit here is that you don't need prefect clean room facilities operating the cargo bay as the satellites are protected until they are in space. 
However this creates problems with the wale mouth door unless it can open more than 90 degree you can only release satellites forward and a bit to the side. You could tilt the payload adapter in orbit so you release and avoid the nose. 
If you can open the door wide you could release to the side who is much better if you carry many containers you could even rotate the payload adapter if you have lots of smaller containers. 
You will obviously need another door if you land and deliver cargo 
 

[Xd the great]

I am actually kinda worried about Starship.

You simply do not see so many rapid unscheduled disassembly on other rocket companies.

or do you?

 

[RCgothic]

2 hours ago, kerbiloid said:

Couldn't they finally hire a reservoir engineer? The humanity has a long history of chemical and gas plants.

If SpaceX aren't already more expert at designing and building cryogenic tanks to withstand flight pressure and flight loads whilst minimising mass than the leading gas plant suppliers then I'll buy a hat and eat it.

This is a core capability for a rocket company.

As @Ultimate Steve points out, anyone can design a tank to hold pressure. Designing it light enough to fit on a vehicle is the hard part. Designing it light enough to be load-bearing rocket is hardest of all.

[sh1pman]

17 minutes ago, Xd the great said:

I am actually kinda worried about Starship.

You simply do not see so many rapid unscheduled disassembly on other rocket companies.

or do you?

 

It’s their design strategy, build a prototype quickly, blow it up, get the data, fix the problem, repeat. 
 

Some other companies need 10 years to build a fuel tank.

Edited June 16, 2020 by sh1pman

[Hannu2]

10 minutes ago, sh1pman said:

It’s their design strategy, build a prototype quickly, blow it up, get the data, fix the problem, repeat. 
 

Some other companies need 10 years to build a fuel tank.

SpaceX's PR is based on publicity. I am sure that other companies make tests too, and fail sometimes, but behind fences without cameras.

SpaceX's development pace is also probably more than all other combined in the world. Their advances in last decade are exceptional. They began from nothing and have taken largest share of world's satellite launches, their reusable rocket is overwhelmingly more advanced and economical than any other manufacturer's products and next they will begin crew transports for NASA. If they get Starship operational for heavy satellite launches in next few years they even increase their distance to others. I hope that Blue Origin can challenge them very soon, because monopoly situation is never good in long run. I do not believe that traditional big companies in USA or Europe can do it without massive political subsidizing.

 

[sh1pman]

29 minutes ago, Hannu2 said:

I do not believe that traditional big companies in USA or Europe can do it without massive political subsidizing.

Or with massive political subsidising. The only possible exception is BO, but they have unlimited money cheat code.

[tater]

 

[Hannu2]

11 minutes ago, sh1pman said:

Or with massive political subsidising. The only possible exception is BO, but they have unlimited money cheat code.

I am quite sure that in both coasts of Atlantic important companies will be subsidized long time. Europeans want to have "own" rocket and Americans want to keep traditional military companies running. Probably they lose commercial launches but states continue to buy launches and fund companies.

I do not also believe that billionaires use their own "unlimited" money to develop space tech for science and humankind. They think always profits, they would not be billionaires otherwise. I believe that also Musk have thought billions from global satellite net when he has given PR talks about colonizing Mars or other bulls... er.. aspirational visions. Strange people, they think money even they have found a bit which gives "unlimited money" from save file. I would certainly think only consuming of money, for example in crazy science projects. But that's why I am middle class nobody and they are billionaires.

[sevenperforce]

1 hour ago, Hannu2 said:

I do not also believe that billionaires use their own "unlimited" money to develop space tech for science and humankind. They think always profits, they would not be billionaires otherwise.

Jeff Bezos spends $1,000,000,000 per year on Blue Origin.

Jeff Bezos earned $2,264,400,000.00 last night.

2 hours ago, Xd the great said:

I am actually kinda worried about Starship.

You simply do not see so many rapid unscheduled disassembly on other rocket companies.

or do you?

Well this was a scheduled disassembly. They were intentionally testing to failure.

2 hours ago, sh1pman said:

Some other companies need 10 years to build a fuel tank.

That burn...like fuel-rich oxyhydrogen staged combustion.

3 hours ago, magnemoe said:

I'm I the only one who don't like the whale mouth door? Yes its probably the lightest solution.
As I see it it has some problems. first is obviously payload integration. 

I don't like it either. Ostensibly they want to avoid seams in the heat shield. But it does seem messy.

[kerbiloid]

Spoiler

  

15 hours ago, CatastrophicFailure said:

Slightly better view of the leak here...

 

 

Watch it from 00:30, right before the exhaust. That's the root of problem.

Spoiler

Four Angry Birds have crossed the tank right before the event and either pierced it, or made unstable by wingwaving.

Of course not snipers but still better than nothing.

Recall! The Ancient Romans never launched rockets when birds were flying wrong.

And pay attention at their formation. Straight line, accurate interval.
Bet, the crows owner is the same coven who caused a hurricane before the Dragon launch.
Or maybe they are ULA crowdrones with guided bomblets.

Spoiler

The event happened on the third one's flyby, and the fourth one stopped waving before that.

Probably, tthe first crow was a recon, the second was a bomber, the third is a photographer, the fourth controls the result.

 

Edited June 16, 2020 by kerbiloid