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SN9

Discussion in 'AviatorChat.com' started by spicedriver, Feb 2, 2021.

  1. spicedriver

    spicedriver F1 Rookie

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  3. Gatorrari

    Gatorrari F1 World Champ
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    Jim Pernikoff
    Was it really THAT noisy?
     
  4. tazandjan

    tazandjan Three Time F1 World Champ
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    Jim- Unbelievably loud, even from a long ways off. Have been to several test firings of rocket engines, and even the smaller ones are really, really loud.

    Elon said it would take a while to stick the landing, just like his Falcons on the barge. Landing a VTVL RLV is not a simple task, but it sure simplifies operations.
     
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  5. jcurry

    jcurry F1 World Champ
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    SN8 almost made the landing. SN9 wasn't even close.
     
  6. carguyjohn350

    carguyjohn350 F1 Rookie
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    Thanks for posting, I hadnt seen this. I saw a headline somewhere that said it took off, flipped over, and exploded, which is really misleading since clearly it launched fine, flipped on purpose, maneuvered fine, and simply hit the ground too hard at landing leading to loss of vehicle and no casualties presumably. Not to go P&R but nice to see the real video.
     
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  8. BJK

    BJK Formula 3

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    Both crash landed ON the landing pad. Sooo, pretty close. :)
    SN8 had low fuel pressure, engines starved.
    SN9, only 1 engine successfully re-lit instead of the required 2 (of 3) for landing. If this happened at a higher altitude, maybe they could have re-lit the other (3rd) engine. But they don't have enough 'landing fuel' to do that.
    Oh well. SN10 is nearly ready to try and get it right. Third times the charm?
    .
     
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  9. kylec

    kylec F1 Rookie
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    You’d think that it exploding right next to the other one would not be a good thing- like piercing the skin.
     
  10. tazandjan

    tazandjan Three Time F1 World Champ
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    One of the technology questions on VTVL RLV engines is always the restart. Sometimes difficult to get fuel to the engines without extensive fuel management devices in the tanks because of changing attitude unless you have separate landing fuel tanks. Another solution is to leave the necessary engines at low thrust, but this uses propellants and many rocket engines have only a limited low thrust capability. They needed two engines to provide roll control.

    They will get it figured out eventually. These are the same things DOD worked on with RLVs for decades with limited success due to lack of funding, so it is good to see industry doing what we wanted to do and making money doing it. Now the ESA thinks reusable is the way of the future, too.
     
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  11. BJK

    BJK Formula 3

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    Starship 'header tanks' plumbing. Supplies fuel to engines for restart and landing.



    .
     
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  13. tazandjan

    tazandjan Three Time F1 World Champ
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    Separate landing tanks guarantee you have enough fuel to land, but cost you some in mass fraction. A trade they decided upfront. It can be very difficult to get a small amount of fuel out of large tanks once the engines shut off and the fuel wants to form a sphere in the center of the tanks under zero G. Settling burns with the reaction control system are one solution, combined with propellant management devices in the tanks, Separate tanks are the simplest solution, but you still have to get the fuel to the engines when you do not have positive G on the airframe all the time during descent.
     
  14. jcurry

    jcurry F1 World Champ
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    The pitch-over maneuver they've been practicing doesn't help. Do you know if they are doing that to add drag to the airframe during descent?
     
  15. tazandjan

    tazandjan Three Time F1 World Champ
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    Normally on a VTVL RLV reentry, you reenter nose first and play AOA and bank angle against heat rate. When you get deep into the atmosphere and are generating lift, you pitch up to start the engines, which also tends push the fuel to the bottom of the tank. You try to time the pitch up so you have just enough fuel to make the landing with a small reserve.
     
  16. BJK

    BJK Formula 3

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    #13 BJK, Feb 4, 2021
    Last edited: Feb 4, 2021
    Yes. Typical low earth orbit re-entry speeds are near 17,500 mph. One side of Starship, including flaps, will be covered in heat shield tiles.
    Remember that all designs are with re-usability in mind. Land, stack on re-used booster, refuel and go.
    Annnd, every pound of fuel or 'design element' added, is one less pound of payload.
    .
     
  17. BJK

    BJK Formula 3

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    SN9 W R E C K A G E

    'Time Stamps' under Description - Jump to 14:30


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  18. Gatorrari

    Gatorrari F1 World Champ
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    As a little kid might say "It fall down and go BOOM!!" Hope they have better luck with SN10.
     
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