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I think SpaceX has proven they know how to design rockets. But they are newcomers to building rockets from welded steel.

walrus01 7y ago
It is my understanding that the pressure vessels are carbon fiber composites. The skin is steel.
- gpm 7y ago
  The skin is the pressure vessel, double walls are a waste of valuable mass. They gave up on carbon fiber awhile ago. *I think they still use small composite overwrapped pressure vessels for fluids they need less of than CH4 and O2, just referring to giving up on carbon for the main tanks.
- nwallin 7y ago
  Do you have a source? My understanding is that the skin is the pressure vessel. The reason for going with stainless steel at all is because it maintains integrity at high temperature. Carbon fiber does not. So a stainless steel combined heatsink and structure can maintain integrity at 1000C or whatever, while carbon fiber+ceramic heatshield will need to hold temperatures below 400C or whatever. And even though the fiber structure is much, much lighter, the amount of heat protection required is massive. And the stainless steel "cheats" by performing double duty. And you get a second free lunch because the heat protection requirements are slimmer. It wouldn't be the first time I've been wrong today though. Nor the second.
  - walrus01 7y ago
    Apparently I have not been following this as closely as I thought I was. This 12 meter diameter tank is from 2016. Not part of current design. https://everydayastronaut.com/stainless-steel-starship/ https://everydayastronaut.com/stainless-steel-starship/
- baking 7y ago
  https://everydayastronaut.com/stainless-steel-starship/ https://everydayastronaut.com/stainless-steel-starship/ Edit: "So in summary. SpaceX chose stainless steel over carbon composites because it’s about as light, it can handle higher temperatures which means less heat shield is need, which then makes it lighter, it reflects heat which means even less heat shield which again makes it even lighter, it’ll be cheaper and quicker to build AND it’ll look FREAKING AWESOME."
gaius_baltar 7y ago
> But they are newcomers to building rockets from welded steel. AFAIK everybody is.
- Gravityloss 7y ago
  Atlas was steel. The first US ICBM and an early space launch vehicle. To this day, the Centaur hydrogen upper stage with RL10 engine is steel. Balloon tanks. They inspired SpaceX heavily.

walrus01 7y ago

It is my understanding that the pressure vessels are carbon fiber composites. The skin is steel.

gpm 7y ago
The skin is the pressure vessel, double walls are a waste of valuable mass. They gave up on carbon fiber awhile ago. *I think they still use small composite overwrapped pressure vessels for fluids they need less of than CH4 and O2, just referring to giving up on carbon for the main tanks.
nwallin 7y ago
Do you have a source? My understanding is that the skin is the pressure vessel. The reason for going with stainless steel at all is because it maintains integrity at high temperature. Carbon fiber does not. So a stainless steel combined heatsink and structure can maintain integrity at 1000C or whatever, while carbon fiber+ceramic heatshield will need to hold temperatures below 400C or whatever. And even though the fiber structure is much, much lighter, the amount of heat protection required is massive. And the stainless steel "cheats" by performing double duty. And you get a second free lunch because the heat protection requirements are slimmer. It wouldn't be the first time I've been wrong today though. Nor the second.
- walrus01 7y ago
  Apparently I have not been following this as closely as I thought I was. This 12 meter diameter tank is from 2016. Not part of current design. https://everydayastronaut.com/stainless-steel-starship/ https://everydayastronaut.com/stainless-steel-starship/
baking 7y ago
https://everydayastronaut.com/stainless-steel-starship/ https://everydayastronaut.com/stainless-steel-starship/ Edit: "So in summary. SpaceX chose stainless steel over carbon composites because it’s about as light, it can handle higher temperatures which means less heat shield is need, which then makes it lighter, it reflects heat which means even less heat shield which again makes it even lighter, it’ll be cheaper and quicker to build AND it’ll look FREAKING AWESOME."

gaius_baltar 7y ago

> But they are newcomers to building rockets from welded steel. AFAIK everybody is.

Gravityloss 7y ago
Atlas was steel. The first US ICBM and an early space launch vehicle. To this day, the Centaur hydrogen upper stage with RL10 engine is steel. Balloon tanks. They inspired SpaceX heavily.