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Falcon 9 / Dragon

Discussion in 'Science' started by MoorKhan, Dec 8, 2010.

  1. Foliage

    Foliage Member

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    [​IMG]
    http://www.weibull.com/hotwire/issue21/hottopics21.htm

    This is why it is safer, the second hand rockets are closer to the bottom of the tub. This is hypothetical of course as they have not actually had a rocket refly enough times to get an end of life failure and get decent statistics however almost all complex mechanical products follow a failure model like this.

    edit: Your warranty on most products is designed to finish before the curve starts heading back up!

    edit2: Read the section on "Burn-In for Leading Edge Technologies" for a good explanation.

    [​IMG]
     
    Last edited: Sep 2, 2016
  2. RnR

    RnR Member

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    Thought it was the Sony Xperia 5 Compact...
     
  3. RobRoySyd

    RobRoySyd Member

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    The question is for a rocket motor how long is the X axis of the bathtub curve?
    The boosters only need to run for 2.5 minutes. I'd imagine designing them to run for twice that adds cost and weight. From an overall design perspective you're being hemmed in in two directions if you want to re-use the rocket.

    None of this though has anything to with what's happened now. The explosion occurred 3 minutes before the engine was to be run, the rocket was still being fuelled. The explosion seems to have started near one of the fuel vents. The Falcon uses densified (cooled) fuel which I guess means both propellant and oxidant needs venting. As best I can see from the video it looks as though something blew apart just before the fireball started.
     
  4. Walshy

    Walshy Member

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    Yep, that was my take on it, too - the initial blast occurred outside the vehicle, so it appears to be a fault with the fuelling system for the second stage. Whether it be venting RP-1 & LOX in too close proximity with a potential ignition source nearby, or some other issue, we'll have to wait for the investigation results.
     
  5. RobRoySyd

    RobRoySyd Member

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    Rather lengthy explanation of the challenges of "rocket science" and what may have gone wrong this time:



    Most likely candidate would be the LOX fuel line running though the KR fuel tank. It seems such a problem arose 40 years ago during the Mercury program. What can happen is the cold LOX freezes the KR causing a fracture in the fuel line. That releases both oxygen and kerosene and then even the tiniest source of ignition and it's all over.

    The Russians decades ago had a problem with kerosene having leaked flooding the pad during fuelling but that didn't go bang until launch. I think Thunderf00t is heading in the right direction, if it was just a fuel leak it wouldn't have been such a fast burn. The objects that can been seen flying through the air just before the blast starts are possibly bits of tank or fuel line from inside the rocket.
     
  6. Quadbox

    Quadbox Member

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    Next tuesday's Elon's very long awaited and much teased keynote at the international astronautical congress in mexico where he's said he's laying out the overall architecture for the MCT and the superheavy lift booster.

    They've pretty much been in information blackout on it for ages, so it's going to be Very Interesting Indeed.

    On the topic of the explosion, fuck they're lucky 39A is almost back in action and that three or four of the close launches on the manifest are polar launches from vandenberg... You'd have to imagine pad 40a'll be out for six months optimistically
     
  7. Sphinx

    Sphinx Member

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    Raptor test went well apparently.
    Going to Mars soon! :thumbup:

    [​IMG]
     
    Last edited: Sep 26, 2016
  8. Sphinx

    Sphinx Member

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  9. tonner78

    tonner78 Member

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    Beyond excited to watch the speech/keynote tonight after work. Love this shit :D:leet:
     
  10. RobRoySyd

    RobRoySyd Member

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    I'd be more impressed if they could reliably get rockets off the ground without them blowing up from issues long ago wrangled by NASA. The latest incident on the pad is now thought to be due to a rupture in a helium pressurisation system taking out a LOX tank.

    Virgin Galactic is no better, the loss of a craft and life was due to significant sloppiness with crew training and a lack of a basic interlock according to the NTSB investigation.

    SpaceX make much of reducing the cost by having reusable rockets. It sounds good but the physics and experience suggests its a marginal idea. The Shuttle proved to be the most expensive and deadly way to get humans into orbit. The physics challenge comes from having to keep fuel in the tanks for braking the descent. That's the very fuel that gives the craft the greatest acceleration. The cost of having to keep that fuel in the tanks impacts the payload that can be carried. That's before the cost of refurbishing the rocket.

    As for the Mars colony as I think already noted so far no such colony on Earth has gone well. A self sustaining Mars colony means humans reproducing there and the few experiments conducted in Earth orbit suggest there's going to be issues.
     
  11. sTeeLzor

    sTeeLzor Member

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    Horse shit. I am glad we have your scientific brain to add to this conversation. One and done. Throw it out.

    Just because its easier to build a whole new one, just because they failed on an attempt does not make it a problem. You realise in industry that you are allowed to make a mistake, miss an inspection, and realise its cost and alter it for next time?

    Not everything is in a neat little box and perfect every single time.
     
  12. PabloEscobar

    PabloEscobar Member

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    The Shuttle didn't use a powered descent, Just a de-orbit burn, a stack of aerobraking and then S turns down to a fast and relatively steep landing.

    It's a bit disingenuous to say that the shuttle is 'the most deadly way to get humans to orbit'. Over its lifetime, the Shuttle had 833 crew members and 14 Deaths. Compared this with the Apollo project, which Killed 3 of 32.

    The Rocket equation is a harsh mistress, and lifting fuel for the sole purpose of descent does make stages bigger than they absolutely need to be, without reusable rocketry, prices will remain ridiculously high. They must have done the math and determined that Extra Fuel + Refurb Costs is less than Building a new rocket each time.
     
  13. Foliage

    Foliage Member

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    Agree, when I see a self contained pressurised experiment on Earth that lasts 3 years without anyone leaving or requiring oxygen from outside.

    It is more the payload size suffers due to carrying that extra fuel and not using it to get into orbit.

    I'm sure they weighed up the payment they get for the payload per kg vs the cost of the rocket itself. They wouldn't do it unless it was cost effective.
     
  14. Jacom

    Jacom Member

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    A quick google search gave me this:

    http://motherboard.vice.com/read/sc...ioxide-into-oxygen-by-zapping-it-with-a-laser

    Mars has plenty of CO2. I don't understand the science very well, but if this process only requires energy, then they can produce oxygen from the Mars atmosphere right? If it required tons more power than solar panels can provide I guess it might not work.
     
  15. RnR

    RnR Member

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    Do we know what the long term effects of living on Mars would be?
     
  16. PabloEscobar

    PabloEscobar Member

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    The rocket is designed for the Payload size (within reason) so I don't think you can really say "The Payload size suffers"

    Sure, you could fit more payload on a rocket if it didn't also carry "landing fuel", But if they needed to carry more payload, they would have designed bigger launch stages. (while still keeping the landing fuel)
     
  17. Sphinx

    Sphinx Member

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    Well NASA ain't doing much in the way of anything right now. SpaceX are the only U.S based option for NASA to contract out to supply their own ISS!
    ULA, ELA, China, India, etc are all just putting up Satellites with conventional rockets - SpaceX is the only one that has a production spaceship program in use (Dragon) and can re-land their first stages on land or sea (for hopeful proven reuse).

    In regards to Falcon 9 track record, they have only had 2 ever mission failures (even if you count the pre-launch static test fire recently):
    https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_Heavy_launches
    Post investigation, SpaceX have announced they are looking to resume launches in November:
    http://gizmodo.com/spacex-figured-out-why-its-expensive-rocket-exploded-1787007827

    They have 41 more future launches already planned for customers apparently:
    http://www.spacex.com/missions

    I say good luck to them. :thumbup:
     
    Last edited: Sep 28, 2016
  18. Sphinx

    Sphinx Member

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    Enjoy:

     
  19. Quadbox

    Quadbox Member

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    lol @ "Issues nasa wrangled years ago"
     
  20. BlueRaven

    BlueRaven Brute force & optimism

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    Billions of dollars of government funding comes in handy when you're "wrangling the issues". :)

    And now SLS is dead in the water thanks to Congress treating it as a pork project (restart production of SSME's for one-time use? Really?!).
    NASA is hamstrung by politicians treating it as a big bucket of money to be distributed to their constituents and not allowing the scientists and engineers to do good science/engineering for the benefit of all, bugger the cost.

    And as stated above it seems that ULA, ESA and other agencies are happy to focus on standard sat launches utilising existing technology.
    Good for science and pre-existing commercial reasons (large scale comms customers etc.) but not so good for pushing the boundaries of innovation.

    Musk firmly believes that such innovation must come from the commercial sector, and that this will only be viable once reusability becomes the norm rather than the exception.
    Their whole business model and ~$60mil per payload costing is based on it.

    Given they have customers lining up around the block, I'm inclined to agree with him.
    Failures will happen, tolerances and safety margins are extremely fine when dealing with this much energy in a controlled explosion.
    But innovation and progress must continue and it's the private sector that will wear the cost.
    Best of luck to them, we live in exciting times.
     

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