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I can contribute one more data point: Space X invented a new alloy steel to drive down the cost of the surface material of Space X rockets to $4/kg. That's some

I can contribute one more data point: Space X invented a new alloy steel to drive down the cost of the surface material of Space X rockets to $4/kg. That's some serious science and engineering. And this improvement is probably a very small one compared with thousands of innovations made by Space X.

steve_adams_86 4y ago
Do you know what prices per kg looked like before this new alloy?
- hintymad 4y ago
  Aluminum lithium alloy was about $40/kg, and carbon fibers about $130/kg, without considering the cost of insulation tile.
  - steve_adams_86 4y ago
    Cool, that’s a significant improvement. I’m not sure how often magnitude-scale improvements occur in material sciences, but my instinct is that it’s rare.
phire 4y ago
Citation needed. Falcon 9 uses a carbon fiber skin over an aluminium honeycomb. And Wikipedia claims that Starship originally used bog-standard 301 Stainless Steal, and later switched to also bog-standard 304L Stainless Steal. The only alloys that I'm aware of SpaceX developing are inconel alloys for hot, oxygen rich parts of their engines.
- someperson 4y ago
  Also PICA-X is a SpaceX variant of a NASA heatshield. It's typical for SpaceX to use the off-the-shelf material initially, then do R&D to customize it for a material that better suits their needs.
- hintymad 4y ago
  IIRC, Musk explained it in a SSB-BPA joint meeting last year. They considered carbon-fiber, aluminum lithium alloy, and 301 steel. It was a fascinating discussion. The materials were great under low temperature, but had other issues as well as degraded performance under high temperature. For instance, carbon-fibers can leak gas (or react with the percolated fuel?). Starship eventually used 30X, a steel alloy.
- someperson 4y ago
  So Starship doesn't use 30X stainless steel?
atkailash 4y ago
fundad 4y ago
We went through all this with the haters about Steve Jobs

steve_adams_86 4y ago

Do you know what prices per kg looked like before this new alloy?

hintymad 4y ago
Aluminum lithium alloy was about $40/kg, and carbon fibers about $130/kg, without considering the cost of insulation tile.
- steve_adams_86 4y ago
  Cool, that’s a significant improvement. I’m not sure how often magnitude-scale improvements occur in material sciences, but my instinct is that it’s rare.

phire 4y ago

Citation needed. Falcon 9 uses a carbon fiber skin over an aluminium honeycomb. And Wikipedia claims that Starship originally used bog-standard 301 Stainless Steal, and later switched to also bog-standard 304L Stainless Steal. The only alloys that I'm aware of SpaceX developing are inconel alloys for hot, oxygen rich parts of their engines.

someperson 4y ago
Also PICA-X is a SpaceX variant of a NASA heatshield. It's typical for SpaceX to use the off-the-shelf material initially, then do R&D to customize it for a material that better suits their needs.
hintymad 4y ago
IIRC, Musk explained it in a SSB-BPA joint meeting last year. They considered carbon-fiber, aluminum lithium alloy, and 301 steel. It was a fascinating discussion. The materials were great under low temperature, but had other issues as well as degraded performance under high temperature. For instance, carbon-fibers can leak gas (or react with the percolated fuel?). Starship eventually used 30X, a steel alloy.
someperson 4y ago
So Starship doesn't use 30X stainless steel?

atkailash 4y ago

fundad 4y ago

We went through all this with the haters about Steve Jobs