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Thread: SpaceX

  1. #3241
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    'm not sure if this has been posted, but what is the configuration of the Starship, LOX on top or below the Methane tank?

  2. #3242
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    Quote Originally Posted by bknight View Post
    'm not sure if this has been posted, but what is the configuration of the Starship, LOX on top or below the Methane tank?
    From what I understand the tank layout is, main LOX tank at the bottom with the CH4 main tank above it. The CH4 header tank is at the base of the CH4 main tank, i.e. between it and the LOX main tank. The LOX header tank is way up in the tip of the nose.

  3. #3243
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    Lox is denser than the methane so it would make sense to put it lower down. I think one of the recent videos showed a "common dome" between the two tanks and said it was LOX on the bottom.

    Seems to have been some sort of tanking test on SN5 yesterday, I'll have to see if I can find how it went.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  4. #3244
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    Quote Originally Posted by Trebuchet View Post
    Lox is denser than the methane so it would make sense to put it lower down. I think one of the recent videos showed a "common dome" between the two tanks and said it was LOX on the bottom.

    Seems to have been some sort of tanking test on SN5 yesterday, I'll have to see if I can find how it went.
    That makes sense. I didn't look at the densities.

  5. #3245
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    Admittedly I hadn't either, just assumed based on molecular weight. So now I did. LOX is 1.141 g/cm^3. Liquid CH4 is .423 g/cm^3. Close to three times.

    I just watched this video from yesterday. Some kind of interesting stuff, including confirmation that the methane tank is on top.
    At 1:12, note the horrible dent in the ring stack on the right. That kind of thing seems inevitable when you've got guys bouncing around on man-lifts. Conventional rocket builds would have elaborate staging around rockets under construction, but there's nothing conventional about this. Absolute game changer if it works.
    At 1:38, old fins are joined by some sort of steel arched structure. The radius of which, as seen at 5:37, appears much greater than that of the Starship rings. Maybe the next generation 18m Starship someone mentioned above? Commenters seem to think it's decoration for a restaurant!
    At 6:35 there's something wrapped in plastic on a platform to the right. Old car body? Almost certainly not but it gives me a late 1950's GM vibe!
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  6. #3246
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    If all goes well, SN-05 static fire Friday (tomorrow)

    Flight soon after, the FAA and FCC permits are in.

  7. #3247
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    Quote Originally Posted by Trebuchet View Post
    Admittedly I hadn't either, just assumed based on molecular weight. So now I did. LOX is 1.141 g/cm^3. Liquid CH4 is .423 g/cm^3. Close to three times.
    And I guessed the oxygen tank would be on top. Why? Because the LOX tank was on top in the Shuttle external tank above the liquid hydrogen tank (.07 g/cm^3) and in the SLS (closely related to the Shuttle ET design). That is a bit over 16 times difference. There must be other design factors than density.

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  8. #3248
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    Quote Originally Posted by Van Rijn View Post
    And I guessed the oxygen tank would be on top. Why? Because the LOX tank was on top in the Shuttle external tank above the liquid hydrogen tank (.07 g/cm^3) and in the SLS (closely related to the Shuttle ET design). That is a bit over 16 times difference. There must be other design factors than density.
    IIRC the LOX tank was on top of the RP-1 in the Saturn, but densities weren't too different, with LOX slightly greater than RP-1, 1.141 vs .81–1.02

  9. #3249
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    I wonder if the deep-cryo (super-cooled) LOX that SpaceX uses has a different density that the literature value for LOX. I assume it does, since I thought the point was to put more in the tank.

    Found this
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  10. #3250
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    Quote Originally Posted by bknight View Post
    IIRC the LOX tank was on top of the RP-1 in the Saturn, but densities weren't too different, with LOX slightly greater than RP-1, 1.141 vs .81–1.02
    I looked that up, because I remembered that the second and third stages used liquid hydrogen. Here’s a diagram:

    http://heroicrelics.org/info/saturn-...n-v-apollo.jpg
    from this page:
    http://heroicrelics.org/info/saturn-...v-general.html

    So the S-IC stage (RP-1) has the oxygen tank on top, but S-II and S-IVB stages (hydrogen) have the oxygen tank on the bottom like the Starship. On the other hand, the Ariane 5 (hydrogen) has the lox tank on top like the ET/SLS. *shrug* Maybe they flip a coin?

    "The problem with quotes on the Internet is that it is hard to verify their authenticity." Abraham Lincoln

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  11. #3251
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    Quote Originally Posted by Van Rijn View Post
    I looked that up, because I remembered that the second and third stages used liquid hydrogen. Here’s a diagram:

    http://heroicrelics.org/info/saturn-...n-v-apollo.jpg
    from this page:
    http://heroicrelics.org/info/saturn-...v-general.html

    So the S-IC stage (RP-1) has the oxygen tank on top, but S-II and S-IVB stages (hydrogen) have the oxygen tank on the bottom like the Starship. On the other hand, the Ariane 5 (hydrogen) has the lox tank on top like the ET/SLS. *shrug* Maybe they flip a coin?
    Well, I'm not a rocket scientist.

  12. #3252
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    I think the "horrible dent" is just minor deformations from something being attached on the inside.

    As for LOX tank location: it's on top for the Falcon 9 as well. As I recall, early Starship concepts had it on top, and it moved to the bottom when the LOX header tank moved to the very nose.

    A high center of gravity assists stability and control during launch and landing. Starship has additional concerns of structural loading and aerodynamic stability during its sideways reentry.

  13. #3253
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    Quote Originally Posted by cjameshuff View Post
    I think the "horrible dent" is just minor deformations from something being attached on the inside.

    As for LOX tank location: it's on top for the Falcon 9 as well. As I recall, early Starship concepts had it on top, and it moved to the bottom when the LOX header tank moved to the very nose.

    A high center of gravity assists stability and control during launch and landing. Starship has additional concerns of structural loading and aerodynamic stability during its sideways reentry.
    What previous rocket program would have tolerated even "minor deformations"?
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  14. #3254
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    Quote Originally Posted by cjameshuff View Post
    Starship has additional concerns of structural loading and aerodynamic stability during its sideways reentry.
    Something I've wondered with its ring construction. I think it looks if it could do with some lengthways strengthening. They must know what they're doing though!

  15. #3255
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    Quote Originally Posted by Trebuchet View Post
    What previous rocket program would have tolerated even "minor deformations"?
    Atlas. The balloon tank stages were pretty wrinkly before they were pressurized.

    https://kpbs.media.clients.ellington...ctory_t800.jpg
    https://forum.nasaspaceflight.com/in...topic=22602.40

  16. #3256
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    And the V2. And while Soyuz tends to be rather smooth, they aren't too concerned about bolting some extra sensor pods left or right.
    With sufficient thrust, water towers fly just fine.

  17. #3257
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    Except for Columbia/Buran shuttles, R-7 was one of the most “draggy” LVs out there.
    Glushko especially would have loved the F-4 Phantom...”the ultimate victory of thrust over aerodynamics”
    I was hoping Bezos would go the squat route via Bono type designs—and Starship 2 winds up fatter too.
    I can’t imagine how many Starlinks that could disgorge.

  18. #3258
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    New video showing hurricane preparations. I was wondering if they'd fold Blue-Zilla down and indeed they did. I hope they've put lots of bolts in the second tier of the new high bay.
    Note the guy near the end shoveling sand into a bag. Stealing it, presumably. He then drives off, having noticed the camera!

    Based on the comments, the site is on the relatively safe side of Hanna.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  19. #3259
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    High Bay 2, Cranezilla, SN-05, and the sites look good, just need Highway 4 to drain and re-appear.

  20. #3260
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    Quote Originally Posted by docmordrid View Post
    High Bay 2, Cranezilla, SN-05, and the sites look good, just need Highway 4 to drain and re-appear.
    I guess this could also be classified as environmental testing for Starship.

  21. #3261
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    Wind shear testing.

  22. #3262
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    If the hurricane path changes a bit, we might see the 150 meter hop before the static fire test.
    With sufficient thrust, water towers fly just fine.

  23. #3263
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    Quote Originally Posted by Nicolas View Post
    If the hurricane path changes a bit, we might see the 150 meter hop before the static fire test.
    Isn't the storm dissipating over Mexico at this point?

    CJSF
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    Davy, Davy Crockett
    There's more than we were taught"

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  24. #3264
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    Quote Originally Posted by publiusr View Post
    Except for Columbia/Buran shuttles, R-7 was one of the most “draggy” LVs out there.
    Glushko especially would have loved the F-4 Phantom...”the ultimate victory of thrust over aerodynamics”
    I was hoping Bezos would go the squat route via Bono type designs—and Starship 2 winds up fatter too.
    I can’t imagine how many Starlinks that could disgorge.
    publiusr

    You have been warned and infracted many times for off-topic posts, but those infractions do not appear to be getting our point across. Maybe a suspension will. We are tolerant of small diversions off the main topic of a thread when they relate to a matter under discussion (like the recent discussion of LOX density), but not seemingly random thoughts about various miscellaneous rockets and aircraft.
    At night the stars put on a show for free (Carole King)

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  25. #3265
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    Quote Originally Posted by Van Rijn View Post
    And I guessed the oxygen tank would be on top. Why? Because the LOX tank was on top in the Shuttle external tank above the liquid hydrogen tank (.07 g/cm^3)
    In the Shuttle case the heavier oxygen is placed on top to minimize the sideways shifting of the center of mass as the external tank empties to minimize the issues of keeping the thrust vector pointed through it. This is an issue that is pretty much unique to the Shuttle design.

  26. #3266
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    Quote Originally Posted by CJSF View Post
    Isn't the storm dissipating over Mexico at this point?

    CJSF
    Yes it's all good now. Just a bit of water left to drain at Boca Chica, SN5 still standing and prepping for static fire as we speak.
    With sufficient thrust, water towers fly just fine.

  27. #3267
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    No static fire tonight, fuel spin valve and TVC issues to fix. Trying again tomorrow.

    https://twitter.com/elonmusk/status/1287965692298268673

  28. #3268
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    Inside the SpaceX spacesuit lab

    https://youtu.be/4LMwKwcMdIg

  29. #3269
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    FCC Special Temporary Authority (STA)

    https://apps.fcc.gov/oetcf/els/repor...ion_seq=101294

    This STA uses information from previous grant 0150-EX-ST-2020 and is necessary to authorize Starship Prototype suborbital test vehicle communications for medium altitude hop tests (max altitude 20km) from the Boca Chica launch pad, and the experimental recovery following the suborbital hops. Trajectory data will be provided directly to NTIA, USAF, and NASA. Launch licensing authority is FAA Office of Commercial Space Transportation.

  30. #3270
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    StarLink L9

    Date: August 1
    Backup date: August 2
    Launch time: 0321 Eastern (0721 UT)

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