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View Diary: New Video of SpaceX Sci-fi "Grasshopper" Rocket Released - Over 1000 ft Hover Flight in June (56 comments)

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  •  The only 'plus' I can see from this is the ability (3+ / 0-)
    Recommended by:
    palantir, Troubadour, sviscusi

    To land in tight spaces, instead of needing a runway. All that fuel it needs to carry to re-entry and land replaces a lot of payload - I still think the 'parasitic' system (like the Rutan design) is more sensible and efficient. This is definitely cool to look at, but seems inefficient.

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    by Fordmandalay on Sun Jul 07, 2013 at 07:58:15 PM PDT

    •  The argument that Elon Musk poses (3+ / 0-)
      Recommended by:
      Drewid, sviscusi, polecat

      is that even though you cut the payload by a certain fraction, you also cut the cost by a factor of a hundred while increasing safety and reliablility by an even larger margin.  And even the decline in payload is only circumstantial because you can just build bigger rockets and still sustain them economically due to much greater demand at the lower price.

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      by Troubadour on Sun Jul 07, 2013 at 08:23:12 PM PDT

      [ Parent ]

    •  I think that the weight of the "spent" first stage (1+ / 0-)
      Recommended by:
      Troubadour

      might be very small compared to its weight with a full load of propellant and a payload.

      The "burn" required to land the nearly-empty first-stage might be very small compared to the launch firings....

      I wonder how much residual fuel is in the current booster when it finishes its launch burn-I'd bet it's a surprising amount, I bet they don't let the booster run til it flames out, I bet that they calculate how much speed change they need to perform the mission and intentionally shut it down after a specific number of seconds rather than let it herky-jerk to completely empty...

      I've wondered if they couldn't figger out a way to soft-land the engines alone, since they are the complicated part, maybe some sort of explosive-bolt affair that separates the engine package from the fuel tanks and deploys a parachute....

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      by leftykook on Sun Jul 07, 2013 at 08:40:29 PM PDT

      [ Parent ]

      •  They have compromised some payload (0+ / 0-)

        to keep more fuel at stage separation for the 1.1.  The cost/benefit is off the charts if they succeed, so there's no reason not to let go of a few million per flight for the possibility of cutting the ultimate cost of orbital spaceflight to 1% of where it is.

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        by Troubadour on Sun Jul 07, 2013 at 08:52:40 PM PDT

        [ Parent ]

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