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Homemade liquid rocket engine all based around a CO2

  1. Dec 22, 2007 #1
    Ok, so if there is a better place for this, please do move it mods, I just couldnt find a place to post project related stuff so I chose this part of the site.
    Anyways, I'm working on a homemade liquid rocket engine all based around a CO2 cartridge combustion chamber. This project also has the possibility to be a hybrid. Anyways, assuming I keep it a liquid engine, I have to ideas for the injection setup. Either just two copper tubes (one for oxidizer and one for fuel) going in at the top, or one tube going in at the middle of the top and some sort of simple manifold that goes around the top and has a few holes drilled into the chamber. I wish I could describe it better, but I can't and I dont have any good schematic drawing program. This is just a fun project for me (ha ha, I'm a geek, I know it) and is not intended to be very precise or powerful. Thanks everyone and happy holidays.
  2. jcsd
  3. Dec 23, 2007 #2


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    The operation of a liquid rocket propulsion system is considered a hazardous (potentially dangerous) activity. It is one thing to design and contruct (without propellant elements, i.e. fuel and oxidizer), but it quite another matter to attempt to use it. For that reason, I would discourage use of a liquid propellant rocket system without the direct supervision of a responsible adult who has direct experience in the use of such systems.

    If one wants to do research or academic study of liquid rocket propulsion systems, then I would recommend this book -

    Modern Engineering for Design of Liquid-Propellant Rocket Engines (Progress in Astronautics and Aeronautics) (Hardcover) published by AIAA.

    Rocket propellant, either liquid or solid, is dangerous, especially for one without any experience. One needs to make sure one complies with federal, state and local ordinances and regulations on the possession and use of rocket propellants and associated materials.

    I'm not sure copper is suitable - certainly not at combustion temperatures. Then there is the matter of differential thermal expansion, strength of materials, and materials combatibility. CO2 cartridges are not designed to be used as 'combustion chambers', but simply as storage vessels.
  4. Dec 23, 2007 #3


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    You're going to use a CO2 canister as a combustion chamber? Am I reading this right?
  5. Dec 23, 2007 #4


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    That sounds very very scary. Those are typically used for a certain other oxidiser-related venture.
  6. Dec 23, 2007 #5
    Thanks, and yes I am very aware of the dangers. It would be used for very short uses with adequate safety measures(i.e. in the middle of nowhere(which happens to be plentiful here in NM), shielding from possible explosions, etc.) The CO2 cartridge that would be used is a 12 gram one, which are rated to 10,000 psi. Oh, and DST I know what you mean, but those are a rather idiotic idea best left to drunk rednecks. Mostly this is just a proof on concept. The kid from PowerLabs (dunno if you've ever heard of it, but its a pretty cool website) has made a similar one before, and he is somewhat of a science prodigy who thinks things out very well. Anyways, thanks everyone and happy holidays.
  7. Dec 23, 2007 #6
    Which oxidizer are you going to use? N2O or O2? Anyways:
    Im not sure i fully understand. You are going to make a liquid or a hybrid? I would strongly recommend a hybrid. Ive attended hybrid rocket testing, and it is able to produce quite an OMPH :D.. You need a very light gas canister. Preferably plastic/carbon something. You are probably not able to make this yourself, so you must search the net. The "fuel" they used under the hybrid test I attended, was regular black plastic, with a hole in the middle.

    I would start by building the engine if I were you. Just get a good tank with N2O in a good vented room with one open wall/retractable wall.. Then you can make an engine, hook it up to the N2O and test. Its much easier this way.. You would be able to make a really good motor. Then retrofitting a small pressure tank and constructing a rocket will be no problem :)
  8. Dec 23, 2007 #7
    Henxan, I am deciding currently or may try both. It is actually not even going to be used in a rocket, its just a stationary test. Anyways, I think both are really cool. Currently, I don't know which oxidizer to use. Those gas-powered whipcream makers use N2O which would be fairly easy to get and retrofit. Oxygen is also not to hard to find either. I do like hybrids for the reasons you listed, especially the wide variety of fuels.
  9. Dec 23, 2007 #8
    But be careful if you start with liquid+liquid/gas fuel. If it explodes it explodes. :D.. You'll probably find good sketches on the internet by the way.. And programs ;)
  10. Dec 23, 2007 #9
    Yeah, I am pretty good with safety and understanding the parameters of what I'm working with (i.e. strengths of materials). I haven't actually been able to find any programs online, if you know of any could you please direct me to them, or them to me.
  11. Dec 23, 2007 #10


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    I've only found numbers like 800-900 psi, and those are room temperature. A CO2 cartridge supplier indicates max. temperature is 50°C. The PowerLabs site simply states a burst pressure of 10 ksi, but that is a guess (theory) and they have not claimed to have tested it.

    I strongly recommend not using a CO2 cartridge for a rocket motor, especially with copper tubing!

    PowerLabs also has a disclaimer
  12. Dec 23, 2007 #11
    Yes, I know that it is burst pressure and I know of the disclaimer. Anyways, I will say it again. This is more of just a project to be built in spare time. I have very little budget (literally pocket change) and will most likely never get very far at all. Another possibility would be to use very low grade solid propellant, (KNO3 and sugar, which I have experience in)
  13. Dec 23, 2007 #12


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    I think you'd be better off using solid propellant and paper tubing. Won't kill anyone if it goes off, at least. Just don't use mercuric fulminate.

    Maybe take some tips off the Tetra-Pak dude and make the first liquid-propellant paper rocket :biggrin:
  14. Dec 23, 2007 #13
    murcuric fulminate ha ha good one. I know a guy who, when in college, heard of a detonation of some fulminate that had been found in the chemistry lab(over 20 lbs. of it). The stuff had been made in like the 20s, so the university decided to get rid of it. A qualified group took about 7 lbs out in the hills a few miles out of town. When it detonated, it shook windows on the far side of the town.
  15. Dec 23, 2007 #14
    I think hybrids are pretty safe. You just have to make sure the burn chamber don't get clogged, and if it does, that you have made the chamber tough enough so it wont explode. (maybe safety vents even). Its probably more dangerous with single propellant.
  16. Mar 8, 2008 #15
    Use Hydrazine as your fuel. Needs no oxidizer or ignition system and undergoes spontaneous combustion at 38 degrees centigrade. It's old school, been around since WWII and the German ME 163.
  17. Mar 8, 2008 #16
    Wow, you musta been bored to dig this up again. Problem is, Hydrazine is probably just a wee bit hard to get a hold of. On par with that would be to just use hydrogen peroxide and a platinum catalyst.
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