Wiki Super Heavy/Starship - General Development Discussion

[ecarfan]

Teslerati now says, quote: “Update: CEO Elon Musk stated on Twitter that the Los Angeles Times’ original report and a partial miscommunication on behalf of SpaceX misconstrued an official statement that early-stage Starship and Super Heavy prototype construction and development would stay in South Texas for the time being. It appears that SpaceX’s Port of LA plans remain largely unchanged.”

And shows this quote from SpaceX: “
“To streamline operations, SpaceX is developing and will test the Starship test vehicle at our site in South Texas. This decision does not impact our current manufacture, design, and launch operations in Hawthorne and Vandenberg Air Force Base in California. Additionally, SpaceX will continue recovery operations of our reusable Falcon rockets and Dragon spacecraft at the Port of Los Angeles.” – SpaceX, January 16th 2019”
———————————————————

This is a bit confusing.

 

[Grendal]

Starship and Falcon Super Heavy will be built in California. It's only this test Starhopper rocket, and possibly other testing vehicles, that is being built and tested in Texas. That doesn't mean they won't be launching the official rockets there in the future. They just won't be manufacturing them there. Possibly assembling them there and the other launch sites though. Starship and Super Heavy are so big that SpaceX can't transport them any other way than by ship or crazy big plane.

Does that clear things up?

 

[ecarfan]

Thanks. So what SpaceX “miscommunication” was Elon referring to that resulted in the LA Times compounding the confusion and publishing an inaccurate story? And the Port of Long Beach representative seemed pretty disappointed.

 

[Grendal]

I expect that someone at LA Times asked a spokesperson at SpaceX what was going on in Texas. The person didn't answer clearly enough and the article writer thought Starship and Super Heavy would be built there, not just the Starhopper test vehicle. I'm guessing the spokesperson didn't make the distinction between the two clear. The article writer is unlikely informed enough to distinguish between two big shiny rocket ships. From there, someone called the Port of Long Beach and asked them how they felt about it and the whole thing snowballed into a big miscommunication mess that Elon had to clear up

 

[mongo]

Thanks. So what SpaceX “miscommunication” was Elon referring to that resulted in the LA Times compounding the confusion and publishing an inaccurate story? And the Port of Long Beach representative seemed pretty disappointed.

Every literal interpretation combined with "thinks not said"

To streamline operations, SpaceX is developing and will test the Starship test vehicle at our site in South Texas.

Turns into
To streamline operations, SpaceX is developing the Starship in South Texas, and will test the Starship test vehicle at our site in South Texas.

This decision does not impact our current manufacture, design, and launch operations in Hawthorne and Vandenberg Air Force Base in California.

Does not mention Port of LA, thus the assumption that PoLA is impacted.

Additionally, SpaceX will continue recovery operations of our reusable Falcon rockets and Dragon spacecraft at the Port of Los Angeles.

PoLA is called out here as only handling recovery, reinforcing the assumed meaning of not being listed in the second sentence.

 

[ecarfan]

Every literal interpretation combined with "thinks not said"

I assume you meant to type “Things not said”.

Clearly communicating is indeed a challenge, whether one is a SpaceX employee talking to an LA Times reporter, or when posting in an online forum.

 

[ecarfan]

SpaceX fits Starship prototype with tank bulkheads as hop test pad progresses

Someone named “Austin Barnard” appears to have flown a drone over the Boca Chica facility and taken some photos showing what’s happening there with the Starhopper.

Here is his photo of what I assume is the Starhopper launch pad that is under construction. While I can understand that a launch pad for hop tests can be kept fairly simple, I do wonder where the flame trench will be.

 

[mongo]

While I can understand that a launch pad for hop tests can be kept fairly simple, I do wonder where the flame trench will be.

Second stage is VTOL from unimproved Mars or moon surface and Earth landing pads, so it needs to work without flame trench in general. This unit is less mass to start, so that likely helps too.

Is trench move to protect the ground equipment than the rocket? I know one of the early day rocket concerns was the vibrations (and I think that is one of the reason for the water system)

 

[ggr]

Excellent read: Elon Musk Interview: Why the Starship Is Built of Stainless Steel

 

[Cosmacelf]

Excellent read: Elon Musk Interview: Why the Starship Is Built of Stainless Steel

Wow, wow, wow. Fascinating that this is all Elon’s idea and he had to convince his engineers. Imagine what Elon could do if he wasn’t running Tesla!

Why does he call this a regenerative heat shield? Just because it doesn’t ablate?

 

[Nikxice]

Great interview. The "counterintuitive" riddle of using stainless steel versus carbon fiber is clearly explained by Elon. Looks like SpaceX is still undecided on whether to use water or fuel for transpiration cooling on the windward (reentry) side of the vehicle.

 

[mongo]

Wow, wow, wow. Fascinating that this is all Elon’s idea and he had to convince his engineers. Imagine what Elon could do if he wasn’t running Tesla!

Why does he call this a regenerative heat shield? Just because it doesn’t ablate?

Regenerative since you can keep pumping water or fuel into the double wall hull and it will keep transpiring out the micropores to cool the skin. As long as you have fluid, it regenerates(ish).

 

[bxr140]

Is trench move to protect the ground equipment than the rocket? I know one of the early day rocket concerns was the vibrations (and I think that is one of the reason for the water system)

Its mostly attenuating the acoustic energy so it doesn't reflect back and destroy the rocket (same for the flame trenches)...but...I think in the big picture deluges are multi-purpose. There's got to be some pad equipment that is less damaged with water suppression.

 

[HVM]

Methane is it...

Elon Musk
‏Verified account @elonmusk
Replying to @PopMech
"When going to ~1750 Kelvin, specific heat is more important than latent heat of vaporization, which is why cryogenic fuel is a slightly better choice than water"
11:31 AM - 22 Jan 2019

Space Development Club:
Replying to @elonmusk @RationalEtienne @PopMech
"Being able to use one of the propellants for coolant also means you don't need to complicate the design and logistics with a water tank."

Elon Musk:
"Yes. Also, despite high outside heat, rapid water vaporization can counter-intuitively cause it to snap freeze & block cooling channels."

https://twitter.com/elonmusk/status/1087794886315819008

 

[ecarfan]

Excellent read: Elon Musk Interview: Why the Starship Is Built of Stainless Steel

I love that guy! How does he think of this stuff? I know, First Principles, logical reasoning, etc.. But it is so hard for adult brains to re-think a difficult problem from square one. Somehow, he does it, while also employing expert level knowledge of multiple fields that he has no formal training in. Sheesh.

In the interview, he appears to be saying that while stainless steel is obviously much denser than carbon fiber, the additional weight of the heat shield material needed with a carbon fiber hull essentially negates the difference. But he wasn’t clear on whether or not a stainless steel hull would be lighter or heavier than a carbon fiber hull plus heat shield.

Exciting times indeed.

 

[ecarfan]

Re-read the interview and wondered about something else that I have no expertise in: I get it that stainless steel is much easier to work with from a manufacturing standpoint than carbon fiber, but how reliable are the welds over multiple duty cycles that involve temperature changes of hundreds of degrees? One weld failure could be disastrous.

Obviously Elon and SpaceX have thought about it and determined that the many stainless steel pieces that will need to be welded together to build the Super Heavy and Spaceship can be done in such a way that the structure is safe. Not perfectly safe, of course, but safe enough.

 

[mongo]

Re-read the interview and wondered about something else that I have no expertise in: I get it that stainless steel is much easier to work with from a manufacturing standpoint than carbon fiber, but how reliable are the welds over multiple duty cycles that involve temperature changes of hundreds of degrees? One weld failure could be disastrous.

Obviously Elon and SpaceX have thought about it and determined that the many stainless steel pieces that will need to be welded together to build the Super Heavy and Spaceship can be done in such a way that the structure is safe. Not perfectly safe, of course, but safe enough.

Falcon 9 tanks are friction stir welded now, much more uniform than MIG/TIG. Weld cracking in general fits into the fracture toughness mentioned. Thermal cycle testing is easily done in the lab.

View of the Friction Stir Welds on Falcon 9 Tank : spacex

 

[Mobius484]

Any chance this could be 3D printed stainless?

 

[mongo]

Any chance this could be 3D printed stainless?

Not at those prices...
3-D is great for complex shapes, especially parts with interior passages that are not accessible on the finished part. This application is all sheets of various thickness stamped or rolled into the proper curve (similar to automotive).

The micro pores can be made via laser.

 

[HVM]

Elon Musk on Twitter

Elon Musk:
"Will probably make booster legs/flaps same as ship, instead of like F9"

Everyday Astronaut @Erdayastronaut:
"Still planning to use methalox RCS thrusters and not cold gas? If so, how do you get those to be quick enough to function as RCS?"

Elon Musk:
"Cold gas thrusters only. Will use body flaps & main engines for landing orientation, so won’t need high thrust reaction control. Simplifies things considerably."

-No more landing to the launch mount?

Anthony Iemole @SpaceXFan97:
"How many engines will be on SuperHeavy? Looks like the engine is to big to fit 31 of them on there."

Elon Musk:
"Still up to 31. Will probably fly with fewer initially in case it blows up."

-lol