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    • CommentAuthorkorkskrew
    • CommentTimeNov 22nd 2019
     
    Posted By: saner
    eta: Will the MK2 fuel tank be insulated too?
    Too? Do you mean instead?

    Unless they change the fundamental concept, the fuel tank will be about 60% of the body of the rocket. It will be made of 301 stainless (or a similar alloy), polished on one side to minimize the emissivity, and covered with thin ceramic tiles on the other side to protect against the worst of the re-entry heating.

    The prototype that blew up (MK1) was never intended to go into orbit, so it never got the tiles.
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      CommentAuthorsaner
    • CommentTimeNov 22nd 2019
     
    Posted By: Andrew PalfreymanGo look at the Mk2 pix. They are legion.


    I have been looking. A link to a couple if you don't mind.


    Posted By: korkskrewToo? Do you mean instead?


    AP replied to me "This is how the Mk.2 is constructed.", about rings I believe. I was asking about the insulation 'too'.


    Where are you guys getting your info on MK2? I can't seem to find much with a search of "spacex starship mk2" for images. Lots of MK1 stuff comes up.
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      CommentAuthorsaner
    • CommentTimeNov 22nd 2019 edited
     
    Posted By: korkskrewUnless they change the fundamental concept, the fuel tank will be about 60% of the body of the rocket. It will be made of 301 stainless (or a similar alloy), polished on one side to minimize the emissivity, and covered with thin ceramic tiles on the other side to protect against the worst of the re-entry heating.

    The prototype that blew up (MK1) was never intended to go into orbit, so it never got the tiles.


    Pretty sure that is not what I was asking about. Must be my lack of clarity.

    The heat shielding for re-entry in not what I am talking about.

    I am trying to find out if the fuel tank(s) is insulated for the roughly -300c liquid going into it. And what method is being used to keep it cool otherwise.
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      CommentAuthorAngus
    • CommentTimeNov 22nd 2019
     
    Just so. Though they do have the advantage that the tank is huge and the surface/volume ratio is lower than you would normally find. Still, the thought of all that LOX turning into O2 at the walls is scary.
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      CommentAuthorsaner
    • CommentTimeNov 22nd 2019 edited
     
    Posted By: AngusStill, the thought of all that LOX turning into O2 at the walls is scary.


    Just don't mention that to the passengers and have them sign a waiver.

    Doesn't bother me too much as there is zero chance I'll ever be near one. And I'm sure the calculations for expected boil off tolerances are good.....
    • CommentAuthorkorkskrew
    • CommentTimeNov 22nd 2019
     
    Posted By: saner
    Posted By: korkskrewUnless they change the fundamental concept, the fuel tank will be about 60% of the body of the rocket. It will be made of 301 stainless (or a similar alloy), polished on one side to minimize the emissivity, and covered with thin ceramic tiles on the other side to protect against the worst of the re-entry heating.

    The prototype that blew up (MK1) was never intended to go into orbit, so it never got the tiles.


    Pretty sure that is not what I was asking about. Must be my lack of clarity.

    The heat shielding for re-entry in not what I am talking about.

    I am trying to find out if the fuel tank(s) is insulated for the roughly -300c liquid going into it. And what method is being used to keep it cool otherwise.
    No insulation.
    •  
      CommentAuthorAngus
    • CommentTimeNov 22nd 2019
     
  1.  
    Minimal protections are implemented for these early prototypes (as you might have imagined). It is not necessary, for example, to provide radiation shielding for the payload volume at this stage of development. My understanding is that the current priority is to validate the flop-flip landing technique (which is new) and the engines in flight (which are new). Thereafter in-orbit refuelling will need to be validated, which is also new.

    Landing on the moon with Starship is going to be interesting for a number of reasons, one of which is that Raptors appear to have difficulty throttling down below about 50%, and surface gravity is about 1/6 gee. The all up unladen mass is 120t or so, so weight is 20t at Luna. Max thrust is about 240t, so 50% is 60t. Landing empty seems inadvisable.
  2.  
    So in addition to using the retro '70s design ethos, he must also remember how good he was at that silly "moon lander" game you could load into the first TI programmable calculators.
    •  
      CommentAuthorsaner
    • CommentTimeNov 22nd 2019
     
    Hi Andrew.


    Posted By: Andrew PalfreymanGo look at the Mk2 pix. They are legion.


    Again, do you have links to any of these MK2 photos. I can't seem to find anything with decent detail. Thanks.
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      CommentAuthorsaner
    • CommentTimeNov 22nd 2019 edited
     
    https://www.teslarati.com/wp-content/uploads/2019/11/Starship-Mk1-pressurized-111819-LabPadre-1-1024x516.jpg


    Stills of before and during pressurization. Notice the panels have started to straighten out from the crumpled candy bar wrapper look they had empty.

    I'll have to ask my pressure vessel engineer and pipeline inspector friends what their thoughts are on this. Seems very questionable engineering to me.

    Can you imagine the Boing!, Tink!, Bang!, Screech! as it reformed the skin? I suspect several welds would have popped at some point before the final BOOM!.

    eta:
    Also, if these things are going to perform like a stainless steel balloon, I would be very interested in seeing what their engineers had to say about the material stresses that deflating and re inflating will cause. Especially given the apparently poor welding techniques I have seen.
    • CommentAuthorkorkskrew
    • CommentTimeNov 22nd 2019 edited
     
    For what it's worth, I think the fact that the very last weld they made to the tank was the one that failed, may be significant. It may mean the failure was caused by a process problem rather than a design problem.
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      CommentAuthorAngus
    • CommentTimeNov 22nd 2019
     
    Is that thing genuinely welded water- (or LOX) tight? Maybe it can get insulation from some excess running down the outside. More and more insulation as the pressure builds up.
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      CommentAuthorsaner
    • CommentTimeNov 22nd 2019
     
    Posted By: AngusIs that thing genuinely welded water- (or LOX) tight? Maybe it can get insulation from some excess running down the outside. More and more insulation as the pressure builds up.


    Maybe some microscopic perforations so it can perspire? Let out the unwanted O2?

    I fear Elon may read this while high........ Kidding Elon!
  3.  
    Posted By: Andrew PalfreymanMax thrust is about 240t, so 50% is 60t.
    Brainfart, sorry
  4.  
    Posted By: sanerAgain, do you have links to any of these MK2 photos. I can't seem to find anything with decent detail. Thanks.

    Mk2 (Florby) & Mk4 in Cocoa
    https://youtu.be/lgUpWknOouw &
    https://youtu.be/8uYvk0C4OFQ & Nov Timelapse
    https://youtu.be/LTOrA3JV4lE

    Photos & Updates
    https://forum.nasaspaceflight.com/index.php?topic=48893.140
    & Discussion
    https://forum.nasaspaceflight.com/index.php?topic=48892.480
  5.  
    Posted By: Andrew Palfreyman
    Posted By: Andrew PalfreymanMax thrust is about 240t, so 50% is 60t.
    Brainfart, sorry


    No wonder I always crashed the TI Moon Lander.
  6.  
    I had the ALU routed through the amygdala
  7.  
    Why Starship popped its top
    https://www.youtube.com/watch?v=nf5q2YlM2mU

    Comms error
    •  
      CommentAuthorTrim
    • CommentTimeNov 23rd 2019
     
    If Astronauts Hibernated on Long Journeys, They’d Need Smaller Spacecraft.

    https://www.universetoday.com/144051/if-astronauts-hibernated-on-long-journeys-theyd-need-smaller-spacecraft/