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Starship Prototype Unveiled

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Re: Starship Prototype Unveiled

#141

Post by balfirevic »

hinkley wrote: post #114
balfirevic wrote: post #73

Earlier quoted context omitted.

> Are we just seeing the outer shell and it's all unobtanium nano-tube composite on the inside? Nope, it's just steel. Outside shell is the tank.

I recall quite a while back, when titanium started first showing up outside of aerospace, that someone had created a titanium-titanium composite by layering plate titanium with titanium cloth and welding it together somehow. Was supposed to be stronger. Wonder if there's a steel equivalent possible. I think the military was looking at a similar material to replace depleted uranium with something non-radioactive (depl…

> I think the military was looking at a similar material to replace depleted uranium with something non-radioactive

I thought the point of depleted uranium projectiles was simply the density of uranium, giving them large impact energy for a given volume. If that's the case, titanium (4.5 g/cm^3) will not even be as good as steel (8 g/cm^3), let alone uranium (19 g/cm^3).

Re: Starship Prototype Unveiled

#142

Post by chasd00 »

drchewbacca wrote: post #89

I am so amazed by the genius of making it out of steel. It's just so completely counter intuitive but has accelerated their progress so much. If they told you the stats of the material, better strength at cryo tempertures meaning mass reduction, higher melting point meaning minimal heat shielding and great thermal conductivity it would be easy to imagine it was some new super composite. Then your head explodes when t…

working on it outside definitely gives the pictures a "bunch of guys with some metal and a lot of free time" feel haha.

Re: Starship Prototype Unveiled

#143

Post by emilecantin »

baybal2 wrote: post #37
jakoblorz wrote: post #29

Earlier quoted context omitted.

https://youtu.be/Sdwy9fzQzl4 Scott Manley does a great job explaining such things!

I'm surprised the guy being a youtuber. He is the codecs guy at Apple Computers

Isn't he an astronomer / astrophysicist? You must be talking about another Scott Manley.

Re: Starship Prototype Unveiled

#144

Post by paragraft »

35787 wrote: post #119
hwillis wrote: post #22

Earlier quoted context omitted.

Definitely not hotdog (assuming that's from stem to stern). Musk wasn't totally clear when describing it, but he said mk3 would be in three months. The circumference of starship is 28.26 meters. For a single weld the entire length of the ship, the roll itself would need to be that wide. The largest rolling mills in the world are ~4 meters wide[1]. They require backup rollers[2], ie rollers that push down the rollers…

Wow what an incredibly substantive comment. I remember pretty clearly he said that there would be a single seam weld. Maybe I’m remembering wrong. Or maybe they’ll seam weld multiple rolls into a really wide roll and the only weld required to turn the final roll into the shell is that final hotdog weld.

I think the idea's to go like a Pringles can, with a spiraling single seam.

Re: Starship Prototype Unveiled

#145

Post by emilecantin »

faead_ wrote: post #30
codeulike wrote: post #8

I totally understand why they've gone for that design but the welded together steel plates really make me think of the sort of thing Wallace and Gromit would build.

he addressed in presentation, from what i remember it had a lot to do with cost. Like $130k/ton with carbon vs $3k/ton with steel. He mentioned a few other factors. Also it allowed them to build outside, not sure if t that is true in production.

As he said in the presentation, it was because at cryogenic temperatures (which is the important part when you're building a liquid oxygen / methane tank) 301 stainless is actually _stronger_ than Al / carbon fiber. It also handles heat much better, which allows you to have a much thinner heatshield.

Both characteristics combine to give a lighter rocket than one built out of Al / carbon fiber.

The price is just the cherry on top.

Re: Starship Prototype Unveiled

#146

Post by justapassenger »

cryptoz wrote: post #64
justapassenger wrote: post #61

Earlier quoted context omitted.

Hopper shows that engine works outside of test lab. That's great, but it's far far away from showing that they solved most of the hard problems. Experience from FH and F9 is useful, but it's a totally different type of spacecraft, with different use-cases, different materials, engines, cooling, etc. There's TONS of new stuff that they have to research, experiment, fail, try again, etc, until it's doing even 50% of wh…

Perhaps I'm misunderstanding something. I thought Hopper was not about Raptor tests but about VTOL as well. The FH had to wait while F9 got down the vertical landing science and engineering (though a lot of tests, explosions, delays). StarHopper seems like it can use those learnings, and that was tested recently. The engine was already functioning on a test stand and mated to Hopper for static fires; the Hopper hop i…

> The general space industry considered reusabable spacecraft that land vertically to be pretty much impossible until F9 and FH did it. But Hopper just does that casually, you don't bat an eye, you don't even comment that Hopper was testing a new rocket dynamics/physics for the math that (almost) only SpaceX has figured out.

VTVL isn't new. To do it you need ability to throttle engine and do trust vectoring - once you have that, it's "fairly" simple math and physics.

SpaceX is first company that commercialized it, and huge props for that. No one cracked economy of it before (and it's not 100% sure that spacex did - no one saw their financials).

> New issues, but not the same ones. The new issues have dramatically smaller turnaround time to resolve.

We'll see, but I'm extremely sceptic about it. With F9/FH SpaceX did amazing but incremental improvements to current rocket technology. Starship has tons of uncharted territories.

Re: Starship Prototype Unveiled

#147

Post by navigatesol »

narrator wrote: post #107
hwillis wrote: post #24

Earlier quoted context omitted.

SpaceX is completely changing the opportunities of getting to space. The reduction in price has been nuts. According to NASA the space shuttle was ~$450 million per launch, or $16,364 per kg to LEO. The Delta 4 Heavy is $12,156 per kg. For some launches it's even higher- the Air Force paid $15,109 per kg for four launches. The Falcon 9 is $62 million, or $2,719 per kg to LEO. The Falcon Heavy is $2,351 per kg when ex…

I think this illustrates what someone who actually understands the engineering being in charge of a company can really do to revolutionize a field. If a non-engineer is in charge of a space company, they'll look at the popular science articles and assume that single launch is the only way to do things. They'll also assume that we just need to get the material science right to be able to do space elevators. They'll as…

I love how we've suddenly decided that all the solid engineering done in the space industry, for decades, was done by fools reading pop science. But now a "real engineer" is showing us the way.

SpaceX is standing on the shoulders of giants.

Re: Starship Prototype Unveiled

#148

Post by emilecantin »

allannienhuis wrote: post #34
faead_ wrote: post #30

Earlier quoted context omitted.

he addressed in presentation, from what i remember it had a lot to do with cost. Like $130k/ton with carbon vs $3k/ton with steel. He mentioned a few other factors. Also it allowed them to build outside, not sure if t that is true in production.

the material isn't the question, it's why they had to weld it together in a patchwork quilt. Elon talked about the next version would simply have rolled coils with a single seam weld (although the cylinders would have to be welded together too), which would be better structurally and cosmetically, and likely lower cost of production. Sounds like they just didn't have the rolling machines to do the job, or perhaps the…

> although the cylinders would have to be welded together too

No, they'll do a helical weld, exactly like large pipes (like this: http://www.xysteelpipe.com/upload/201512118145340710.jpg)

You basically need to do that as the steel rolls off the press, though, which is why they didn't do that for Mk I. They'll need to cold roll the steel onsite.

Re: Starship Prototype Unveiled

#149

Post by chucksmash »

35787 wrote: post #119
hwillis wrote: post #22

Earlier quoted context omitted.

Definitely not hotdog (assuming that's from stem to stern). Musk wasn't totally clear when describing it, but he said mk3 would be in three months. The circumference of starship is 28.26 meters. For a single weld the entire length of the ship, the roll itself would need to be that wide. The largest rolling mills in the world are ~4 meters wide[1]. They require backup rollers[2], ie rollers that push down the rollers…

Wow what an incredibly substantive comment. I remember pretty clearly he said that there would be a single seam weld. Maybe I’m remembering wrong. Or maybe they’ll seam weld multiple rolls into a really wide roll and the only weld required to turn the final roll into the shell is that final hotdog weld.

I think when Elon said "there will be a single seam weld" (which I also remember), he meant this in comparison to the current welds.

It's been 12 hours and I only skimmed the video, so I might be misremembering what he said. My understanding was this: Mk1 is welded from plates so at each layer of the stack you have n-1 welds holding the n plates together. My understanding of his comment was that the steel coils will wrap around the major axis of the rocket but instead of each layer containing n-1 welds to join n plates, there will just be one weld in each layer to join the beginning and end of that coil. That would still leave you with welds joining the different layers of coils but only one "seam" weld along the rocket's major axis.

Re: Starship Prototype Unveiled

#150

Post by greglindahl »

baybal2 wrote: post #67
faead_ wrote: post #30

Earlier quoted context omitted.

he addressed in presentation, from what i remember it had a lot to do with cost. Like $130k/ton with carbon vs $3k/ton with steel. He mentioned a few other factors. Also it allowed them to build outside, not sure if t that is true in production.

Imagine the autoclave the size of a rocket. Composite tanks on few rockets being flown with them are made in one of a kind, purpose built autoclaves

Out-of-autoclave methods are mature and common these days.
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