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SpaceX F9 - Comm Crew DM-1 - LC-39A

Discussion in 'SpaceX' started by Grendal, Nov 24, 2018.

  1. mongo

    mongo Well-Known Member

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    • Informative x 2
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  2. ecarfan

    ecarfan Well-Known Member

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    Yes, during the post launch press conference Elon indicated that while at the moment the SpaceX Crew Dragon team is totally focused on what NASA needs, in the future the capsule could be used for non-NASA purposes to take people to orbit. But SpaceX would need to make a least a couple of unmanned Crew Dragon flights to test and verify retropropulsive capsule landings, which would cost over $100 million for sure. That would be a big cost for SpaceX to absorb and then try to recoup from future space tourism flights.
     
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  3. AudubonB

    AudubonB One can NOT induce accuracy with precision!

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    Thought I'd share here (as it's where it belongs) why my eyes popped when I read this line on one of the 'net news forums.

    SpaceX Crew Dragon built to carry human heads home from ISS



    Just what is it they do up on the ISS? Do dragons have anything to do with this?:eek:
     
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  4. Yggdrasill

    Yggdrasill Active Member

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    Requires much less energy and space to simply carry heads. And then they just plug them into cyborg bodies on the space station.
     
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  5. N5329K

    N5329K Active Member

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    Watching the capsule come down under canopies, I wondered about the inherent stability (or lack of it) of a 4-chute system vs a 3-canopy system. There seemed to be a lot of partial collapses and reinflations going on as the chutes brushed up against each other. I don't recall seeing much of that on earlier recoveries and it might make for a kind of nerve-wracking ride. Anyone know?
    Robin
     
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  6. mongo

    mongo Well-Known Member

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    I was wonder the same thing in terms of how the chutes stay separated. I'm guessing the length of the lines force the full canopies away from the center axis.The fourth chute was a later addition for redundancy. With all 4 deployed, they may only need 75% effectiveness each.
     
  7. AudubonB

    AudubonB One can NOT induce accuracy with precision!

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    I was struck by the efficacy of the 'chutes - that final 500...300...100...0 meters seemed to me to take amazingly long times. But from the viewpoint of the human cargo - heads or full body - I'll strongly suspect they've no way to assess whether there is any entanglement or not. If this is the case, then the only nerves being wracked would be those of the outside viewers.
     
  8. SMAlset

    SMAlset Well-Known Member

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    Can’t help but now wonder what readings she came back with, especially reentry.
     
  9. e-FTW

    e-FTW New electron smell

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    The ablative heat shield flaring off had me think back to the Space Shuttle re-entries. I was very focused on the trail above the capsule and looking for any anomalies. Could not help it.

    As for the chutes, a few things I wonder about:
    • That did look like quite the carnival ride for Ripley, with plenty of bobbing and weaving and spinning.
    • Two chutes swapped position with each other in the last few seconds. Wonder if that is a problem they will need to look at.
    • The chute landing right on top of the capsule is probably just an annoyance, unless it could pull the capsule in tip it over with the help of wave action
     
  10. Yggdrasill

    Yggdrasill Active Member

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    Funny, I had the exact opposite reaction. Timed it to around 10 seconds between each callout, so about 10 m/s. That's still pretty fast - like 20-ish mph. If you have a car accident at 20 mph, you will feel sore. But the water and the seats probably help dampen the blow by quite a bit.

    I do think the occupants would feel the chutes moving around. Mostly as vertical acceleration/deceleration. As the drag of the chutes varies, the speed might vary in the area 10-15 m/s. Something like that.
     
  11. Grendal

    Grendal SpaceX Moderator

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    [​IMG]
    [​IMG]
     
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  12. e-FTW

    e-FTW New electron smell

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    “Toasted marshmallow” indeed!
    Although it reminded my wife of BB-8. :)
     
  13. f-stop

    f-stop Active Member

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    What a fantastic mission, from start to end. I caught the final docking sequence as well as re-entry and splashdown on the live broadcast, and now I can’t stop watching this great time-lapse replay of docking, complete with a nice little nod to 2001: A Space Odyssey

     
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  14. e-FTW

    e-FTW New electron smell

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    That is a pretty cool video. It looks like it slammed into the ISS hard! Pretty funny when you have seen the normal speed replay.

    My favorite part of this is seeing the amount of work Crew Dragon put in to stay exactly where it needed to be during the hold phase.
     
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  15. mongo

    mongo Well-Known Member

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    Yeah, orbital mechanics are weird. Unless they are docking at the leading or trailing edge orbit wise (in line with the center of mass), the orbital period and/or inclination of the Dragon is different than ISS and it needs to keep changing velocity to stay in the same relative position. On top of that, the ISS doesn't turn off it's station keeping positional system, so Dragon has to adjust to its movements also.

    I thought it was cool how the zero velocity path of the hold points insure the Dragon won't impact the station in case of total power failure.
     
  16. ecarfan

    ecarfan Well-Known Member

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    Okay, I think I nailed it. :cool: Today on twitter...

    FE396F6D-CAEB-4B96-9C85-853B0CF3DC5B.jpeg
    9EC7A68F-CE97-45E1-9597-B33363142D1C.jpeg
     
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  17. Bobfitz1

    Bobfitz1 Active Member

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    #217 Bobfitz1, Mar 10, 2019
    Last edited: Mar 10, 2019
    Yes! There will be lots of once used Dragon IIs available for space tourist flights and maybe some educational multi day orbital flights.
    Since capsule and first stage can be reused a number of times, the price to take a few millionaires up at a time is going to be much less than it has ever been. After a few years and several dozen safe retropulsive landings, NASA may finally come around and leave the water splashdowns to old movies of Apollo landings.
     
  18. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    Have any of us seen inside that Celestial Buddy Earth?
     
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  19. Bobfitz1

    Bobfitz1 Active Member

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    Do you believe to establish safety of Dragon retropulsive landings SpaceX would need to do several launches to put Dragon into LEO and then bring it back down to a soft earth landing?

    How would that be a better test than launching a Dragon to some altitude (as was done earlier) and bringing it back down to a soft landing?
    And/or landing a number of cargo flights to ISS retropulsively, which would cost next to nothing versus a sea recovery?

    Has SpaceX ever layed out in detail how a retropulsive landing from orbit would work? Like at what altitude and speed would the Dracos be lit and how much fuel it will take without parachutes? Intuitively I would think it would take less fuel to land retropulsively after parachutes are deployed and reduced capsule's speed and altitude. What am I missing? Super Dracos could be started and confirmed to be working perfectly before jettisoning parachutes. It shouldn't be impossible to have 3 shoots in reserve just in case something goes with Dracos before the landing.
     
  20. Yggdrasill

    Yggdrasill Active Member

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    #220 Yggdrasill, Mar 11, 2019
    Last edited: Mar 11, 2019
    I haven't seen SpaceX specify anthing like that. But I would think you would want to wait as long as possible. Let the atmosphere do as much work as possible before spending precious fuel on slowing down. (The faster you're going, the more drag you have, and the more effective the braking.) So you would probably wait until under 5 km over the surface. Maybe 10-20 seconds before impact.

    20 seconds should be enough to get the main chutes out, if Super Dracos fail to light up. And 8 Super Dracos with a lot of throttle range allows for a lot of redundancy, anyway. You would need to have like three failures on adjacent Super Dracos before the chutes would be needed.

    If you don't deploy the chutes, they could probably be reused on the next flight with minimal refurbishment.
     

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