
SpaceX's Starship SN4 prototype fires rocket engine for first time - spking
https://www.space.com/spacex-starship-sn4-engine-static-fire-test.html
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gameswithgo
Does anyone with real expertise in aerospace have thoughts about Musk's choice
to use steel instead of carbon fiber for star ship? Does his arguments make
sense or is it likely just a cost saving measure?

Would future Falcon rockets also switch to steel?

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calaphos
I don't know about steel but carbon fiber has so far never succeeded as a
material for cryogenic rockets or fuel tanks.

The proposed space shuttle successor was designed around carbon fiber fuel
tanks / hull and engineering problems with them eventually killed the project.

The material struggles with low temperatures of cryogenic fuels (brittle),
high temperatures of re-entry (just burns), oxidation in oxygen tanks. Also
they apparently tend to sponatiously combust with rocket fuels.

Some reference: [https://www.compositesworld.com/articles/an-update-on-
compos...](https://www.compositesworld.com/articles/an-update-on-composite-
tanks-for-cryogens)

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greglindahl
RocketLab's rocket has carbon fiber tanks.

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elteto
But the scale is much, much smaller than Starship.

If I understand correctly after you pass a certain tank radius you basically
step into “nobody’s ever done this with CF before”, which is not a good place
to be for SpaceX. Starship was on that spectrum.

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dwaltrip
Nice milestone. I think the first test hop to 150m will be in a few weeks.
Very exciting!

