Oh yeah. Replace the stainless steel by carbon fibre, give it to your pals of Boing and instead of being ready in 2030 for 2.3 billion it will be ready in 2050 for 50 billion.
Much better for making your friends rich.
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The tiny Electron is entirely carbon, isn't it?
Their new Neutron has a fully reusable first stage, also out of carbon fiber. For Neutron, they have the largest automated fiber placement machine known to exist:
Yea but isn‘t that the point of the Starship? It has a bunch of unusual design choices regarding reusability and payload capacity, and then the rest of the owl is drawn around them.
I‘m not a rocket-scientist but I would hazard a guess they picked the best material given the options, right?
Stainless steel was specifically chosen so that starship wouldn't need a heat shield and would survive re-entry with transpiration cooling. This would save substantial weight and make rapid reusability easy. The problem is that after designing starship around the stainless steel construction, they found that the transpiration cooling system wasn't workable, so now they have a stainless steel hull and a heat shield.
Further, I do not believe the drawbacks of stainless steel were fully appreciated at the time. Stainless steel on paper looks like it has better strength to weight ratio than aluminum, especially at the cryogenic temperatures of starship's fuel tanks. However a steel tank wall with the same strength as an aluminum wall is much thinner and so you wind up with different failure modes, namely buckling. In practice, a rocket made from steel is heavier than a rocket made from aluminum. This was why the Atlas rockets used stainless steel but subsequent rockets switched to aluminum in the first place.
Additionally, at the time much hooplah was made about stainless steel being cheaper and more formable which would reduce production costs. This is just nonsense. Stainless steel is expensive and tough to work with, which is why we don't use it for creating large structures despite its desirable material properties. It may be favorable compared to titanium, which was likely the only other option when transpiration cooling was the game plan, but for the current design aluminum would be far cheaper in addition to being lighter.
Now I'm sure SpaceX did some analysis after the transpiration cooling didn't work out and asked whether it made sense to start the design over and retool everything instead of continuing on with the stainless steel, and they decided at the time no. Since then they have had several further setbacks. The increased weight required them to reduce safety features, which may have contributed to some of its earlier losses. Starship has had to grow considerably and increase thrust to accommodate for these shortcomings. Would SpaceX have made the same decision to continue with the stainless with the benefit of hindsight? I can't say. But with the exception of a few chinese startups trying to carbon copy starship, other rocket manufacturers have not adopted stainless steel, likely with good reason.
The whole point of a reusable launch system is the cost of the vehicle is amortized over many launches, so you can use expensive, high performance materials.
HLS requires on-orbit refueling. Anything from 10 to 20 refueling launches will be required. Did you think it required one refueling launch? The SH+SS stack will never be reusable or reliable enough to accomplish the refueling operation in time and on budget.
This means one moon mission will require the use of 10 launch pads and probably 20 complete stacks to even be feasible, because reuse will not help one iota.
Their upper stage reuse will never pan out. Sure they will catch a few, then they will remove the engines and stick the rest in a shredder for scraps to be melted down and recycled.
Elon's HLS is completely detached from reality. I won't even call it a SpaceX system because it's unlikely anyone but Elon came up with it.
Not that this actually helps with any thesis of "Yee Haw, look at Us! We're America! We're number one!"
* And now I'm worrying the initials might have been deliberate on his part; hadn't even considered that before seeing your comment…
You seem like commenting on a situation as one would comment about a moon visuals by looking at it without a telescope. But maybe I'm wrong and you are very close to SpaceX engineers and know some folks that work there or other internals...
But you should then have known that Tesla/SpaceX is very well known to remove stupid requirements or solutions if there is much better alternative. And they don't leave stupid decisions there.
I'm no expert that I can attribute the durability of the vehicle to the choice of stainless steel or whatever alloy they have there, but me and online folks have been amazed at IFT1 when starship tumbled and didn't break apart... or IFT11 when heat tiles were purposefully removed on critical spots and the ship still landed. Maybe suffered burn-thru but it didn't prevent a soft ocean splashdown.
Can it be attributed to stainless steel? I'm no engineer, so I don't know. It's just that the observable result is amazing.
>This means one moon mission will require the use of 10 launch pads
The refueling ships are to be launched weeks/months in advance, one at a time. If you look at the rate of Falcon launches this is nothing out of the ordinary.
I've worked directly with both SpaceX and Tesla; this is patently false. Tesla's worse than SpaceX but both are terrible at removing stupid and obsolete requirements.
> I'm no engineer, so I don't know.
I am an engineer. Starship's "durability" is neither particularly technically impressive, nor evidence that stainless steel was a good, nonetheless optimal, material choice.
That's revisionist history.
https://www.teslarati.com/spacex-elon-musk-nixes-starship-sw...
Starship was switched to stainless steel in 2018. It was originally supposed to have an all-metallic heat shield. Ceramic heat shields for critical areas were added months later in march 2019, only in July of 2019 did the windward ceramic heat shield get added, which was after the starhopper prototype had flown and several more prototypes were already being built, and transpiration was still in active development at the time. Transpiration cooling was not dropped until 2020. The heat shield has been steadily growing since then, with the addition of more tiles to cover a larger area and an ablative underlayment to provide more protection to the underlying steel.
> It is not. In 2019, carbon fiber was $135/kg with 35% scrap (so effective cost was $200/kg) vs. $3/kg for stainless steel. That's a two orders of magnitude difference in raw materials.
And what did aluminum cost at the time? Yes stainless is cheap compared to the most expensive alternative, that does not make it cheap.
> 300-series stainless (301/304L) is widely used precisely because it is formable (301 work-hardens to high strength) and readily weldable (304L).
Work hardening is bad for formability.
> it's still much easier to work with than aerospace aluminum-lithium, which requires specialized friction-stir welding and tight process control.
Lithium aluminum is an exotic aluminum alloy. You would use an alloy like 7005 which is weldable.
> There's no evidence that Starship has reduced safety features to compensate for stainless steel + heat shield weight.
That is what reduced margin means. Every rocket has less safety features than it would if weight were not an issue. The more weight increases, the more everything has to give to still remain capable of completing the mission. IFT 9's failure was due to Starship relying on autogenous supercharging to save weight. No one can say how much better starship would be if it had more margin, but it undoubtedly would be better.
If you were to ask Musk technical questions, he would make up shit like he has done hundreds of times in the interviews.
That’s absurd.
Either way, I’d personally rather today’s Nazis of all flavors to be dead. At the very least they seem a lot dumber than the old ones.