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Spark igniter for rocket

  1. Oct 24, 2006 #1

    Aki

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    Okay, so I'm building a liquid propulsion rocket, about 4m tall, with a 2000lb trust. The propellants used are liquid oxygen and kerosene. Now the trouble is to find a way to ignite the fuels to start the combustion. Do you guys have any ideas? Thanks!
     
    Last edited: Oct 24, 2006
  2. jcsd
  3. Oct 24, 2006 #2
    Is that even legal...

    A 12 foot rocket with out permits, I dont think so.
     
  4. Oct 24, 2006 #3

    Danger

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    Once you have the fuel flowing, I'm partial to using a flashbulb with the glass cut off. Nothing like a bit of magnesium wool to get things rocking. :biggrin:
     
  5. Oct 24, 2006 #4

    FredGarvin

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    2000 Lbf? Damn. You're using LOX and kerosene? Damn. How are you storing the LOX?
     
    Last edited: Oct 24, 2006
  6. Oct 24, 2006 #5

    Mech_Engineer

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    Sounds pretty scary, I hope you stand way the heck back when you launch this thing... and I hope it doesn't land on anyone on the way back down. You DO realize you'll need some pretty heavy duty permits for this kind of stuff right?

    That being said, I think the space shuttle uses large "sparkers" that throw hot sparks directly below the nozzle. I'm not really sure how they work, just trying to remember from videos I have seen. Once the fuel starts, it is ignited by the sparks. You could also try electrical ignition such as a hot wire, or something like a barbeque sparker.

    BTW, igniting the fuel is the easy part, how did you even make this 4m rocket in the first place?
     
    Last edited: Oct 24, 2006
  7. Oct 24, 2006 #6

    LURCH

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    I was thinking of the same thing; possibly with road flares? That might be a bit pf overkill, but you could be dang sure that puppy's gonna light!:grumpy:
     
  8. Oct 24, 2006 #7

    Aki

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    Well to address everyone's concerns, this is an university student project team, and our goal is to build a reusable rocket capable of carrying a payload. We have obtained a permit from the Canadian rocketry association for launches. There are approximately 30 people working on this, and this project started about 3 years ago.

    So far, I've looked at the idea of an "augmented spark plug". It's a spark plug withing a tiny chamber mounted above the combustion chamber. So a tiny bit of lox and kerosene will be injected into the tiny chamber and the spark plug will ignite it. Afterwards, this flame will spread into the main combustion chamber where more lox and kerosene will be injected.

    I'm open to comments :)
     
  9. Oct 25, 2006 #8
    How about a glow plug like device. A metal conductor you can heat initially at the launch pad using a current, then which remains hot (by the ignited rocket) throughout the burn. I guess the main filament would burn out, so it would be a one off thing.

    Or some blue touch paper.....hehe.....why complicate things.
     
  10. Oct 25, 2006 #9

    Danger

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    Just got a different sort of idea here. If you can incorporate a small spring-loaded piston in a cylinder (think 'pellet gun' here), an orifice from it could be installed in the combustion chamber. Remotely triggering the piston to release would force the air through into the fuel mixture. The heat of compression with the proper orifice size should be in the area of 1,000 degrees F.. That temperature is only for a fraction of a second, but should be enough to get things cooking. It was the ignition system for the caseless ammo in the old Daisy VL .22 rifle.
     
  11. Oct 25, 2006 #10
    for a low tech solution, you could use magnesium-water reaction. just put a magnesium cap at the nozzle and have something squirt water at it out of the launch pad :/ although it might not be the safest idea....
     
  12. Oct 26, 2006 #11

    Danger

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    I'm no chemistry wizard by any means, but I've never seen an adverse reaction involving magnesium and water. Are you thinking of sodium? If so, not a bad idea.
     
  13. Oct 26, 2006 #12

    Mech_Engineer

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    I think you mean potassium and water. Doesn't sound like a very effective solution to me.
     
    Last edited: Oct 26, 2006
  14. Oct 27, 2006 #13

    FredGarvin

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    Let's get the preliminarys out of the way. Are you incorporating small pumps to move the liquid propellants? How are they stored and mixed in the vehicle? Do you have a premix/ignition chamber incorporated in the design? Are you atomizing the fuel? Since you are going with a liquid based system, this brings up the question as to whether or not you need more spark energy.

    From what I have seen of the big rocketry guys, they use solid propellants. They also use a heaftier version of the old Estes igniter which is basically two wires whose exposed ends are inclose proximity to create a spark. Since you are going with a liquid based system, this brings up the question as to whether or not you need more spark energy.
     
  15. Oct 28, 2006 #14
    Magnesium & Water = Hydrogen gas, you still have the ignition problem

    A quick google brings this up http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1512585

    Which describes one system, it also mentions a problem with the type of ignition system i suggested which ive heard mentioned before.

    Best watch your eyebrows....
     
    Last edited: Oct 28, 2006
  16. Nov 14, 2006 #15
    May I suggest a solution that was used by the Germans on the V-2? They used a pinwheel firework placed in the rocket engine throat to ignite the fuel/oxidizer mixture. Or you could use a sparkling, wand-like firework that is very popular with children in America on July 4th celebrations. lots of sparks from that!
    Another idea is a piezoelectric sparker, like what is used for pushbutton starters on barbeques.:smile:
     
  17. Nov 14, 2006 #16
    I would use a simple wire ignition system. Take two insulated wires separated by 1/8th inch with a cotton ball soaked in gasoline or kerosene attached to it. Create your spark with an automotive or small engine ignition coil.

    -carp
    PropulsionAccess.com
     
  18. Nov 14, 2006 #17
    You could pick up a $25 stun gun at a local flea market. Solder positive and negative leads to it.
     
  19. Nov 14, 2006 #18

    Danger

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    Not in Canada, he can't. Stun guns are classed as Prohibited Weapons up here, in the same category as switchblades, machine guns, grenades, etc.. Go figger... :rolleyes:
     
  20. Nov 15, 2006 #19
    Can you tell me what the pressure will be in you combustion chamber?

    carp
    PropulsionAccess.com
     
  21. Nov 17, 2006 #20

    Aki

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    It will be 100psi
     
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