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Late April Falcon Heavy Demo

Discussion in 'SpaceX' started by Chris TX, Jan 16, 2016.

  1. Chris TX

    Chris TX Active Member

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    Does anyone know if this demo will also include a triple landing attempt?

    Also, if anyone has an inside track on how to watch this from the control center, please PM me. I just might be in Florida around those dates ;)
     
  2. chickensevil

    chickensevil Active Member

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    I think right now, they are only allowed to land on booster per LZ. Because I think when they built LZ1 they said that even though they have like 3 alternative pads there, they are only cleared to land one booster at a time. Maybe after the success of their previous landing at LZ1 and their continued proof of direct hits on their stated targets (last one they said was within like 4.5 feet of the target center) that they might be able to get this restriction lifted... but we will have to wait and see.

    If they did, I suspect the first 2 boosters would come back to site, and the third would be forced to land on a barge. Unless they put a super heavy fake payload on top to keep the center booster separation speed under 6000km/h. This was the stated reason for needing to perfect the barge landing at some point:

    Elon's Twitter
     
  3. Ben W

    Ben W P85 #61, Roadster #108

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    They do have two droneships... So I suppose they could land two boosters on separate droneships, and one booster back at the launch site?

    The real impressive thing would be if they could land two boosters on one droneship... That would take some serious, uh, collets.
     
  4. scaesare

    scaesare Active Member

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    From a risk standpoint, I wonder if separate LZ's are preferable anyway... so that way if one stage fall down go boom!, it doesn't wipe out the other two that just touched down next to it.
     
  5. chickensevil

    chickensevil Active Member

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    tumblr_inline_o02xmqk1Ms1romqng_1280.jpg

    This is a rendering, but you can see that they are rather spaced out. All of these are at LZ1.

    CWyUOajWoAAKRtI-580x300.jpg

    On the main central pad to give you an idea of how *BIG* it is (That is a person standing in the middle).

    main-qimg-ec2e18d722dc3222da120f7138476a12.jpg

    and the size of one booster on that pad (it easily fits within the X on the pad)

    So what I am getting at is that unless something goes seriously wrong with the guidance software and or the thrusters directing the vehicle, one should be far enough away from the other than it wouldn't interfere should one tip over or come in too hard.

    I am assuming the reason they were planning for 4 pads at one site is in case of explosion on one they can still land on another while the destroyed pad is repaired.

    - - - Updated - - -

    Sorry, the rendering actually has 5 pads, you just can't see one in the screen grab from the film, because it is focused on the booster itself. That booster is landing on an out-of-frame pad at the bottom of the image.
     
  6. pgiralt

    pgiralt Active Member

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    I think they should call the maneuver of flipping the three first stages back for landing "The Triple Lindy" :)
     
  7. scaesare

    scaesare Active Member

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    Ah cool, thanks.. I assumed pad and LZ were synonymous... it appears not.
     
  8. chickensevil

    chickensevil Active Member

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    It is also assuming that when they completed construction of the pad(s) that they did all of them. They may have only actually completed just the one so far and the others may still be in progress. No one has gotten any photos that I am aware of, other than official photos/videos released by the company. And the satellite photos are way outdated... Google re-purpose your imaging contract for the aerial satellite pronto! We need new images!

    But yes, end-state would be that the facility should be able to handle more than 1 inbound booster, Last I heard they haven't gotten clearance to bring back more than 1 per site. I would also anticipate a cautious approach by SpaceX as well, where they will likely test a water/barge landing where they come down in close proximity to each other. Because it is more than just them landing close together. They will be landing around the same time (at least the first two), and the return path will keep two independent boosters flying in close proximity the whole way. So if you miss-adjust your trajectories you could easily put them on a collision course for each other and it would likely cost fuel and resources to emergency burn away from one another so they don't blow up in the sky.

    Speculation of course, but it would seem to me that they would remain within hundreds of feet of each other the whole way.
     
  9. freds

    freds Member

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    That's assuming they all start back at the same time. Given the speed that they are traveling, delaying the boost back burn on one of them for say ten seconds would give lots of separation.
     
  10. hockeythug

    hockeythug Active Member

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    #10 hockeythug, Jan 21, 2016
    Last edited by a moderator: Mar 13, 2016
    Here is the video from where the screen grabs came from if you want to watch:

     
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  11. chickensevil

    chickensevil Active Member

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    Given that fuel levels are calculated to be very specific I wouldn't think that would be a wise choice. While it won't be continuing to speed up at that point, letting it continue to travel down range for mere seconds is additional multiple miles they have to recover from which would require more fuel.

    I'm not saying that's not a possibility, just that depending on fuel reserves, it may not be the smartest option. They both separate at exactly the same time so other than minor distance discrepancies between the two landing pads (relative to the launch pad) they should feasibly cone down around the same time. Delaying one might be fine on a barge landing (no boost back), but coming back to base isn't really helping things to waste the fuel. So it might depend on if they want to come back to land or a barge.

    Honestly, they might happily opt for the barge since they need the practice. But at least one will need to come back to base since they only have two barges (assuming they bring JRTI back from CA.)
     
  12. scaesare

    scaesare Active Member

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    #12 scaesare, Jan 22, 2016
    Last edited by a moderator: Mar 13, 2016
    Ah, yeah... now that you sent that (thanks!) I recall watchingthat some time ago. Now that ww have a siccessful landing recovery under our belt, it's cool to see again though.

    Clearly, with 5 pads depicted on that LZ, Tesla plans a Falcon9 Uberheavy!
     
  13. ecarfan

    ecarfan Well-Known Member

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    Seen that video before, but watching it again, it doesn't get old! It will be unbelievably awesome when we get to see those multiple first stage landings happen in real life.
     
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  14. ggr

    ggr Roadster R80 537, SigS P85 29

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    The current idea as I understand it is for the two outer boosters to run at full thrust from takeoff, until they reach their fuel limits, separate, and boost back (maybe with a slight delay for one of them). The center booster will have done all the throttling needed to not exceed Max Q (aerodynamic pressure) and will continue its burn for a while longer, before separating from the second stage.
     
  15. Grendal

    Grendal Active Member

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    At the speeds the boosters are travelling, even one second will give ample room for there to be no chance of collision. Realistically, even if they were to maneuver together the chance of a collision would be very unlikely. The greatest chance for collision would be in the second after separation, after that, there is just too much space for any real possibility.

    But give one booster an extra second and then you've removed even the slightest possibility.
     
  16. chickensevil

    chickensevil Active Member

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    If they can actually do what was originally put forward all three boosters would be firing at the same time. There would be a crossfeed on the connections so the center booster is getting fuel from the sides such that at separation the center should still be near full of fuel. It would discard the sides and now dead weight and continue firing the rocket forward (although may slow down to allow a clean separation).

    It should be noted that as I recall noone has been able to make a cross feed type system work before. So this will be yet another "it can't be done" that SpaceX puts to bed as possible.
     
  17. ggr

    ggr Roadster R80 537, SigS P85 29

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    That was the original plan, but I don't think they even want to try any more. The throttling is necessary anyway, and gives most of the benefits of the crossfeed, without most of the complexity.
     
  18. chickensevil

    chickensevil Active Member

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    What makes you say that?
     
  19. JRod0802

    JRod0802 Member

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    I know this hasn't been updated in a while, but according to the SpaceX website:

    Falcon Heavy | SpaceX

    Has there been more news on that front, ggr? I'd be interested to read about it.
     
  20. ggr

    ggr Roadster R80 537, SigS P85 29

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    I follow NasaSpaceFlight.com fairly regularly, and that seems to be the consensus view over there. See, for example, a posting by @LouScheffer a few articles before the one this link points at (I don't know how to link to that one given that my search found the second one that quoted it).
    Now, I admit that I might have confabulated; I didn't find anyone from SpaceX saying anything like that. And I might have misremembered that this is the way D4 does it and thought that was the official plan for FH. Time will tell.
     

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