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Single-stage-to-orbit ssto

  1. Dec 15, 2004 #1

    cronxeh

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    I was just having a good day and thought I'd start some commotion :approve:


    What do you guys think about SSTO (single-stage-to-orbit) from submersible position (say, from 2 km below sea level) - straight to surface - to air - to space ?

    I can almost imagine the Aerospace old timers grabbing their pacemakers and reaching for the oxygen masks, dialing 911 and searching for a bottle of Validol. But seriously. What would it take (In terms of structural design) to build a ship that could go from high pressures of sea to rapid changing atmospheres, temperatures and finally shield from radiation and provide insulation?

    How much power and of what kind (I'm hinting on nuclear here) would it take to achieve this? Isnt it the time we stop being ignorant, relying on chemical boosters to get us to space, and start using the nuclear-powered engines (which NASA developed very successfully back in 60's and revised in the 80's)?

    I understand it may be costly. It may be dangerous but not hazardous if handled properly. There are engineering challenges, but in the event humanity succeeded in achieving this milestone, we would leap into the next generation of knowledge
     
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  3. Dec 16, 2004 #2

    enigma

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    [tex]\delta V=-g_0*I_{sp}*ln(\frac{mf}{mi})[/tex]

    The delta V is sea level gravity times the rocket's specific impulse times the natural logarithm of the ending mass over the initial mass.

    Is the idealized formula for a single stage to orbit rocket. It takes a velocity of 7800m/s to be in LEO, and it takes (approximately) 1500m/s in aerodynamic drag and gravity losses to get into space.

    Isp for chemical rockets runs between 300 and 450, depending on type of fuel and motor design.

    Playing around with those numbers will show you that for a SSTO, you need between 90% (very generous) and 95% (lower bound) of the total fueled mass to be fuel.

    Modern ohio class submarines have crush depths of between 2000 and 2250 feet and their operating depths are around 1000 feet, so 2km underwater is certainly out of reach. That number is based on the yield stress of the steel, so barring any miraculous alloys, you'd be hard pressed to go much deeper. The ballistic missile submarines can't launch from keel depths of more than around 100 feet.

    I'd also be willing to wager that in our lifetime at least, there will not be a rocket launch where the first stage is nuclear (which would give 800-900 Isp).

    If someone came to me and asked me to help them design one, I'd tell them they were crazy
     
  4. Dec 16, 2004 #3

    cronxeh

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    Thats a lot of great information, thank you enigma

    Another idea (instead of nuclear).. what if you use electromagnetic force to spin the cone-shaped light-weight 'bullet' ship and launch it into orbit from ground.. how many G forces would one expect to encounter on initial impulse?

    http://archives.cnn.com/2002/TECH/space/01/03/maglev.launches/

    Sort of like this, except instead of maglev the whole idea is a scaled up barrel of a gun with EM-entrapment of the ship and a very stable structure
     
  5. Dec 16, 2004 #4

    enigma

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    depends on the length of the track :biggrin:

    For any "reasonable" length of track, higher than a human can take, for sure.

    You also have the problem of needing to be going the final velocity at low altitudes (with all that atmospheric drag). You wouldn't have much left of the spacecraft by the time it got to orbit without tremendous heat-shielding. You'd also lose communications during launch and the ability to use airodynamics for guidance and steering as well.
     
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