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Aerospace New Kind of Rocket Booster

  1. Aug 3, 2008 #1
    I heard about the XSpace rocket failing yet again. Rockets are notoriously susceptible to component failure because of the extreme temperatures and vibrations inherent with rockets. So obviously the fewer moving parts the more reliable the system would be and the added benefit of less parts to inspect for maintenance reduces costs.

    So what is it that I'm proposing as a new kind of rocket booster? I'm sure many here may remember old science fiction movies where rockets where launched from rail systems that looked like roller coasters. What if instead of launching a rocket from such a rail system wasn't a rocket engine but a magnetic lift. The construction of a magnetic lift from permanent magnets is configured like a solenoid system with a tapered funnel. Such a system has a controlled acceleration that increases as the funnel gets smaller in diameter. The rocket is harnessed in a carrier that is magnetized. The carrier is immediately released upon exiting the funnel and the rocket engine is fired. Such a magnetic lift could be miles long and achieve supersonic speeds.

    This approach removes the need for the rocket booster but the dependency of complex liquid propellant rocket engines remains. If however the payload carrying rocket where made of lighter materials and a simpler liquid propellant were used cost reduction and reliability can be achieved.

    Rather than use a liquid oxygen system how about utilizing pressurized oxygen within the propellant. This is very similar to solid propellant systems that contain the oxidizer within its chemical composition. The problem with the approach is the weight of the tanks to withstand the pressure. Here the use of something like titanium could solve the problem.

    One problem I can foresee with the mag lift solution are the shock waves as the rocket exceeds the speed of sound within the funnel. The amount of air displaced in the funnel by the rocket's high speed needs to be released somehow. Also the use of pressurized oxygen in the fuel could pre-oxidized it making the fuel unusable.

    So I've got an idea where can I get practical data to put together a proposal for this solution I'm proposing?

  2. jcsd
  3. Aug 3, 2008 #2


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  4. Aug 3, 2008 #3
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  6. Aug 3, 2008 #5


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    I really shudder when people throw around terms like
    Do you really think that, with the price per pound to send something into space, that pretty much all options in those arenas haven't been looked at? Seriously. Not just NASA, but all of Europe and Japan have been working on this for years. Do you really think that someone is going to say "Hey. We should make this thing lighter." "Why didn't I think of that?" Come on. Since you are throwing the terms around, what are some options to the existing Hydrazene or HO2 that have more than proven themselves?

    The main reason pressurized oxygen isn't used like I think you are suggesting is because it has a tendency to turn into a bomb, not a controlled burn.
  7. Aug 3, 2008 #6
    No they haven't, e.g. The XPrize winners, NASA hasn't developed any suborbital vehicle made of composite material or developed a solid propellant engine that can be shut down at any point during its burn. How did they achieve this miracle that NASA could never do? They feed the solid propellant pressurized oxygen, shutting off the oxygen at will shut down the rocket engine. When the shuttle craft fires its solid propellant engines its the point of no return...

    The specific impulse of these propellants are not as good as oxygen based fuel burning.

    Perhaps but I have yet to find anything that specifically states that or any experiment that has proven the inefficacy of pressurized oxygen.

  8. Aug 4, 2008 #7


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    If you are holding up Spaceship One as your end all be all, you are not comparing apples to apples. The only operational benefit to a hybrid is that you can throttle the motor. Being able to shut one down in flight provides what benefit other than a safety factor?

    Last time I checked, the new Ares boosters are fiber wound.

    Are you comparing these to air breathing engines? Sources please. It is usually stated that hybrids have a better Isp, however they have lower density Isp which means a larger sized motor.

    IIRC the Isp of the shuttles solid rocket booster was just about equivalent, if not a bit higher than Spaceship One's engine. As a matter of fact, the shuttles SRB has the same component in it that Rutan's does for the fuel, just a smaller percentage.
  9. Aug 4, 2008 #8
    Come on, give me a break! Burt Ratan's approach was really radical. I mean rather than use retro rockets to position the spacecraft for reentry the way the space shuttle does it, Burt, ingeniously, shifted the spacecraft's center of gravity so it would not dive back into the atmosphere nose first! Then shift the cg again so it would fly like a plane. Absolutely brilliant!

    So are they the end all be all? I feel more excitement and vision from Burt Ratan's group than I do from NASA's efforts thus far. At least Ratan's group gives each and every one of us the vision that expressing ideas are possible and possible in a big way...

  10. Aug 5, 2008 #9


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    It was radical, but it is equivalent to throwing a stone up in the air and watching it fall back down. You and many others are so used to seeing what NASA and other countries do that you have totally lost touch with what huge technological feats are being performed. I'm not saying that he didn't do something cool, but what use does it have? Give me a break.

    NASA filled the pool. Rutan is peeing in it.
  11. Aug 5, 2008 #10


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    Most importantly, let's not forget that SpaceShip One was a SUB-orbital vehicle. It wasn't anywhere near the required specific energy for orbit of the Earth, never mind escape velocity. So comparing it against proven production spacecraft is a premature at best (even SpaceShipTwo won't be achieving orbit, it's only going to 68 miles).

    I think that you're overhyping the "radical genius" of the feathered re-entry a bit as well. It's an ok idea for these specific sub-orbital vehicles because they have relatively slow re-entry speed. For orbital vehicles, the feathered approach will not work.


    I am excited by the prospects of a civilian-run space company, but hailing Rutan and Virgin Galactic as the most advanced and radical company in the business is a little over the top, and saying they beat the heck out of NASA's achievements is just plain wrong. They are two comletely different entities, solving different problems. When SpaceShip3 comes out (Rutan's orbital vehicle) I suspect it will end up being a lot more "standard" in terms of what heat-shielded spacecraft have looked like in the past.
  12. Aug 5, 2008 #11
    Easy Fred, Rutan has earned his props! His was a really slick development to throttle a solid rocket. Understand, this motor cannot be turned off, just throttled back. It is only good for short flights as the fuel continues to smolder until spent, and when it is ‘off’, it requires ignition and warm-up, it is not ‘instant on’ like a hypergolic liquid fueled rocket. Spaceship one also never achieves orbital speeds and so requires much less heat shielding, and seconds in space does not challenge life support systems the way days or months do. The big issue of oxygen is the cryogenic temperature it requires for storage, all rockets are potential bombs waiting to go off.
  13. Aug 5, 2008 #12


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    Rutan did not develop the Hybrid rocket motor used in SpaceShipOne, a company called SpaceDev did (SpaceDev bought the hybrid rocket patents and test data from out-of-business American Rocket Company, and further developed them). AFAIK, Rutan conceptualized and designed White Night and SpaceShipOne, including the "feather" technique for SpaceShipOne's re-entry. Outsourcing things like motor design is good engineering practice, especially when dealing with complex system design on a budget.



    Last edited: Aug 5, 2008
  14. Aug 5, 2008 #13


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    Don't get me wrong, Rutan definitely has my admiration, especially in the design regime. He is the top designer of our day. What I have issue with is when people don't take the Spaceship One achievement in the proper context like ME pointed out. It's not apples to apples by any means. Rutan has a different goal in mind with his venture, which is a tourism enterprise. NASA and the like have an exploration desire which requires their designs to be more flexible and utilitarian.

    Are you referring to the motor currently used? That one is a hybrid, not a solid rocket. It has a liquid oxidizer component.

    For some reason I assumed that since the OP made direct mention of not using liquid oxygen in his idea, that it would have to be in the gaseous phase. Of course there are no details of how this would be accomplished. I guess the OP would have to clarify what he meant in that aspect.
  15. Aug 5, 2008 #14
    nevermind the toxicity of hydrazine and hypergolics

    oh, it is quite efficient. almost the most efficient for any liquid propellant. maybe you could use fluorine as the oxidizer, its even better than LOX. nevermind that the exhaust is (gaseous) HF acid rather than (harmless) H2O vapor

    pressurized oxygen, or liquid oxygen? there is a distinct difference that should be noted
  16. Aug 5, 2008 #15
    ding! ding! ding! ding!

    we have a winner! hell, by the same token, NASA's X-15 could be a "spaceship" if Rutan's is.

    SS2 won't be achieveing its orbit not because its altitude, but because its speed. you could orbit at 5 miles, it would just an unreasonable amount of thrust. if you look up the definition of "orbit" there is no specification on altitude, just speed such that the vehicle falls around the orbited body [a side note, when Apollo touched down on the moon small dust particles were put into orbit around the moon at less than 100 feet AGL, naturally they hit hills and soforth, which ended their orbit]

    orbital velocity for the earth is approximately 17,000 miles per hour, depending on altitude ;) (try that for confusing). aerodynamics heating at a couple hundred mph (rutan) is quite low, i dare say negligable - compared to the next example. aerodynamics heating at Mach 26, on the other hand requires all this ugly shielding, lending to the capsule or shuttle tile idea. deploying feathers at that speed would ensure you look like a bullet (or ICBM reentry vehicle) coming back home on fire. thats why NASA uses RCS and rutan could use the CG shifting idea. do you know how much weight you would have to shift on the shuttle to move the CG any appreciable distance? it weights 200,000 lbs, you can work out the moment balance if you like
  17. Aug 5, 2008 #16
    maybe because the SRB's are only used from on-burnout operation. when the shuttle takes off, lift = thrust. when its horizontal lift = ~0. there is no reason to throttle the SRB's they are only used for their thrust to reduce the amount of fuel that the ET has to carry. if they dont need the thrust (aborted take off) blow the bolts, and they'll pull away, or bolw their case, and thrust goes to 0.

    you need to compare rutan's hybrid to the shuttle's main engines. that would be apples to apples. both are throttleable main propulsion devices, and the SSME's destroy hybrids in almost all categories (except cost)

    this would be somewhat akin to a C-130 with JATO takeoff, and saying that this upstart company using jet engines is way better than JATO bottles
  18. Aug 22, 2008 #17


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    I think that the magnetic acceleration is unnecessarily complicated. Perhaps the use of a steam catipult, like those used on aircraft carriers, would be easier and more reliable. The steam could be leeched off from a power plant, like they do on the carriers. The railing should run up the western slope of a fairly tall mountain (to get to thinner atmosphere while travelling eastward). The area to the east of the launch facility should be unpopulated (which is why we normally launch off of the East Coast).

    The problem of breaking the sound barrier could be mitigated by enclosing the rail in a wind tunnel, and acceleating the air inside to nearly Mach1. Then, the orbiter could accelerate to almost Mach2 without ever making a sonic boom.

    So, what we would need is a tall mountain range with a slope of about 45o and power plants near the base on the western side, and an unpopulated region on the eastern side, as close to the Equator as possible. To me, this suggests southern California. Outside the US, Equador sounds ideal. The capitol city of Quito has many power plants, and Mt Kotopoxy (sp?) is very tall, almost perfectly conical, and in a sparsely-populated area.
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