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Questions Regarding Homemade Liquid Fuel Engine

  1. Jul 22, 2014 #1
    For the last six or so months I've recaptured my childhood love of rockets (I'm now in college), and have spent a great deal of time both reacquainting myself with the basic information and also learning more about the engineering and technical side of them (now that I've learned things like orbital mechanics, basic engineering, common sense, etc...). I've also been obsessed with designing my own small rocket from scratch and I haven't been able to shake the idea from my head. I have come here with a couple questions regarding this potential project. I don't think I can stress enough that this is only a hypothetical project right now.

    1) Is it safe?
    Obviously I would take extreme caution handling all materials, wouldn't ignite anything while I am anywhere close or anything is in direct line of sight of the engine. I more want to know if this is such a dangerous idea that I shouldn't even try or if it's something which could be achieved with the proper level of safety involved.

    2) Propellant Cost Minimization
    The first fuel/oxidizer combo my mind jumped to was liquid oxygen and some undecided -ane fuel. I was thinking the fuel would be easy to come by and I believe I know how to prepare liquid oxygen from liquid nitrogen (which I know how to obtain). It didn't occur to me at the time how costly these are. Are there cheaper solutions? Gasoline I have realized would be a possibility, but that wouldn't reduce the cost of Nitrogen and besides I don't love the idea of burning gasoline everywhere.

    3) Am I allowed to do this?
    I've fired off model rockets before and they bore me to death. Were I to do this I would want the final product to be something which I could make more complex and frankly cooler than any model rocket could be. I basically want to know if the learned of physicsforums think that I could achieve that in a homemade setting and without requiring rocket permits (whatever the hell those are).

    Thank you very much!
  2. jcsd
  3. Jul 23, 2014 #2


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    Welcome to PF.

    1. Yes, it is dangerous. It is probably too dangerous to be acceptable here at PF. This thread will probably be closed.

    PF specialises in the study of physics, and not in dangerous activities that others may copy and use it for less honest purposes.

    2. Lox and diesel fuel is cheap.

    3. Your home country may have rules to do with the possession or use of rockets that rise above a certain height.

    There are several other forums on the web that experiment with gas turbines, ram jets and rockets.
    I suggest that you find a local group in your country, or a forum or website that specialises in rocket discussion.
  4. Jul 23, 2014 #3


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    Handling LOX is inherently dangerous. Not only can you injure yourself because LOX is cryogenic (that means it's cold enough to cause serious injury if you spill it on your skin), but the presence of gaseous oxygen in high concentration can be toxic if you breathe it.


    Gaseous oxygen in high concentration is itself a serious fire hazard. Some oils will ignite spontaneously on contact with pure oxygen, and even a small fire which could be quickly controlled under normal circumstances can turn into a raging inferno if supplied with pure oxygen. Oxygen gas can saturate your clothes and other flammable material, just waiting for a spark to turn you, not the rocket, into a Roman candle.

    There's a reason model rockets use solid fuel, and safety is a big part of it.
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