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Stainless steel spaceships... Elon Musk built it

Discussion in 'Gadgets & Gear' started by dirc, Jan 9, 2019.

Tags:
  1. dirc

    dirc

    668
    Jan 31, 2018
    So, as many of us, I'm into steel and metallurgy and have been since I was a young kid. (the benefits of having a dad who worked at the large steel mill for 40 years)

    Elon Musk's spaceship is stainless steel ;)
    https://arstechnica.com/science/2019/01/elon-musk-is-really-really-excited-about-his-starship/

    some of his tweets:
    • The vehicle's exterior will be made from a stainless-steel alloy that will not buckle and will remain stable on the launchpad even when unpressurized. The strength and weight of "full hard stainless" at cold temperatures is slightly better than carbon fiber, at room temperature it is worse, and at high temperature it is vastly better.
    • The metallic skin of Starship will get too hot for paint, so it will have a stainless mirror finish. It will need much less shielding as a result, and areas that take the brunt of atmospheric entry heating will be activity cooled with residual liquid methane. As a result, "Starship will look like liquid silver."

    So, what's your best guess about the composition of his ss?
    I hope @Larrin sees this :)

    My guess, If I had to make one... is something like 316H ? It's high strength and temp... only about 0.1% carbon, and 10-14% nickel, 2-3% moly

    Anyway, I look forward to hearing info/updates/news about this. If anyone has knowledge of better structural ss, please share : )
     
  2. Larrin

    Larrin Gold Member Gold Member

    Jan 17, 2004
    Yay steel wins again! Take that aluminum.
     
    hugofeynman likes this.
  3. dirc

    dirc

    668
    Jan 31, 2018
    you think 316H or a similar variant is most likely? Or is there some newer nitrogen variant of this grade/class of ss?
     
  4. hugofeynman

    hugofeynman Gold Member Gold Member

    395
    Jan 18, 2011
    And take that, Titanium!:D
     
  5. Larrin

    Larrin Gold Member Gold Member

    Jan 17, 2004
    Probably some boring stainless steel. Full hard just means it's cold rolled material. It's not really my area though.
     
  6. dirc

    dirc

    668
    Jan 31, 2018
    Hardly boring - I thought it existed (nitrogen structural ss), and I was right; it's called DUPLEX 2205 http://jamesduva.com/wp-content/uploads/2017/08/JDI-material-2205-specification-sheet.pdf
    "2205 is a ferritic-austenitic stainless steel which combines many of the beneficial properties of both ferritic and austenitic steels."

    Tensile Strength (KSI) 65
    Yield Strength (KSI) 90 (this is about 2 or 3 times higher than 316 ss)

    C 0.03
    Cr 21-23
    Fe Bal
    Mn 2.0
    Mo 2.5–3.5
    N 0.08–0.20
    Ni 4.5–6.5
    P 0.03
    S 0.02
    Si 1.0
     
  7. knarfeng

    knarfeng senex morosus moderator Staff Member Super Mod Moderator

    Jul 30, 2006
    Pipe dream. (literally, since 2205 is typically used for pipe.)
    If stainless steel were really a viable option, aircraft would have stainless steel skins.
    It isn't.
    They don't.
    Too heavy.
    upload_2019-1-9_21-26-15.png
    1.4 times as strong as 2024T351 aluminum.
    2.8 times as heavy.
    half again as strong, weighs three times as much.
    That's what we call a "no fly".
     
    Charlie Mike and Uncle Timbo like this.
  8. Lapedog

    Lapedog Gold Member Gold Member

    Dec 7, 2016
    Definitely 8cr13mov.
     
    Charlie Mike likes this.
  9. Planterz

    Planterz Gold Member Gold Member

    Mar 26, 2004
    Budd RB-1 Conestoga.

    https://en.wikipedia.org/wiki/Budd_RB_Conestoga

    Made by the same company that built the Zephyr train, the company that also pioneered "shot welding" of stainless steel. Designed and made during WWII in anticipation of an aluminum shortage that might cripple the war effort. Originally 200 were ordered, but the supply of aluminum held out, and the order was cut to 25, and only 17 were delivered.

    Only one survives, basically derelict, baking in the desert sun about 10 miles from me.

    Budd.jpg

    OK, it's not a spaceship. It wasn't even pressurized. But they made a stainless steel production aircraft in 1943, and as you can see it's not a pile of rust.
     
    Charlie Mike likes this.
  10. WValtakis

    WValtakis Gold Member Gold Member

    May 29, 2004
    Judging by the wrinkles, that's a REALLY thin skin...way thinner than I'd think a pressurized vessel would need.

    ~Chip
     
  11. dirc

    dirc

    668
    Jan 31, 2018
    Well, good thing it's not an airplane... it's a space ship that will experience MUCH higher temperatures, and thus the extra weight in using ss is acceptable. Most aluminum alloys rate mechanical strength up to about 380F... I think they're planning on going double or triple that temp. Stainless Steel will retain strength at far higher temps.
     
    Last edited: Jan 10, 2019 at 8:28 AM
    marchone likes this.
  12. knarfeng

    knarfeng senex morosus moderator Staff Member Super Mod Moderator

    Jul 30, 2006
    True. Wasn't looking at reentry.
    But steel still won't take the heat of reentry. Stainless tops out at about 1200F to remain structural. To go higher you need nickel alloys. The shuttle skin saw 3000F. The amount of methane necessary to cool the skin to a temperature at which steel would retain its strength would be enormous. I have a hard time believing that "residual" methane from the launch fuel would be sufficient.
     
  13. Danke42

    Danke42

    Feb 10, 2015
    Maybe he's building it out a bunch of melted down MIG 25s.
     
  14. Uncle Timbo

    Uncle Timbo Gold Member Gold Member

    Nov 23, 2005
    Elon's on crack. He's graduated up from pot.
    I'll bet he wishes he could take that huff and puff, back.
     

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