Homemade rocket ignitor

Discussion in 'The Projects Forum' started by Alkado, Mar 14, 2009.

  1. Alkado

    Thread Starter New Member

    Mar 14, 2009
    1
    0
    To ignite my rocket engine, a thin wire folds up into the insides of the engine and when headed with a power source it will burn out the engine and launch.

    ________
    engine | /------
    o===== <-Ignitor
    | \______
    ---------


    Theres a cheap drawing of it, the two wires on the right are where the circuit connects to heat the wire. the "o" is some sort of material that burns easily when the wires are heated.

    What im using:
    I have a 6v battery for a power source and 18 guage copper wire to hook it up using alligator clips to the battery and open connection to the ignitor.

    ________ v-- splice
    engine | /------x-----------------------^ <-alligator
    o===== /--<8__8 clips
    | \______x_______________/ | | <-6v battery
    --------- |___|


    Problem:
    Ive been testing with a match to see if a thin filament of copper wire would heat up and light a match. Thing is, it only works when the 18guage copper wire is about 1-2 inches long, if i get some wire about 12 inches long the match wont light, i then feel the copper filament and it seems its not getting as hot.

    Question:
    Using 1 foot of 18 guage copper wire on each battery prong, how can i keep the thin filament of copper wire hot enough to light the match (meaning its hot enough to light the rocket engine).
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    The resistance of the wires reduces the current through the circuit and thus the filament does not get hot enough. Use thicker wires to reduce the total resistance of the circuit or use a higher voltage battery.
     
  3. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    Take your 18ga Wire, strip the insulation off of it, and take one strand of the smaller gauge wires that make up the 18ga wire.

    If you are using solid core wire, find some stranded wire to get a single strand.

    Wrap the bare wire around the fuse/match/ignitor, make sure it doesn't brush against itself, alligator clip each side, and put a > 10A Current through the clips.

    I've used this for instantly launching many rockets at the same time with excellent results. Finer wire needs only a couple turns and can be closer to desired ignition point, it also vaporizes faster with the same amount of current.

    BE CAREFUL. You are essentially building/blowing open air fuses for high intensity heat! These temperatures can leave permanent scars, not to mention sting more than a little bit for quite a while!
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Model rocket ignitors are generally made from thin-gauge Nichrome wire. This wire formulation has a much higher resistance than copper wire. Therefore, the power in the battery is dissipated in the Nichrome wire instead of the copper wire. The Nichrome wire becomes very hot, while the copper wire stays cool.

    I have issues with your schematic plan. You do not show a launch safety key, or lights to show when the igniter is safe or is armed.

    Safety in rocketry is no joke; even if they are "merely" models.

    Please, please conduct your rocketry hobby in accordance within the NAR guidelines.
    Their website is here:
    http://www.nar.org

    A good source for model rockets:
    http://www.estesrockets.com/

    Growing up in the 50's and 60's was a very special time. The space race was on. It was enthralling. I still have the pictures I drew of the rockets of the time; far too large to scan for the forum. I nearly burned my parent's homes down, twice with my "rocket experiments". :eek: Dad understood my passion, and found Estes rockets for me - for a safe outlet.

    To make an already-too-long story short, there's a satellite that's been in orbit for 15+ years now with my "tagline" written in it; "Wook was here".

    Keep your dreams alive. Be safe. And perhaps one day, your tagline will be in space too.
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    I still have a lot of the model rockets I built. Kids don't care about safety, which is why I used AC one time to replace the 12 car battery. Dad did notice the lights blinking, but didn't put 2+2 together, fortunately for my pride and other things. When he came out to see what was going on I had the evidence firmly hide.

    That safety key is necessary, among other things. Is there a reason you don't want to use the igniters that come with the engines?

    Back when they were available I used flash bulbs, a centauri fuse, and masking taped the flash bulb with the fuse going going into the engine, which worked great for clustering.
     
    Last edited: Mar 15, 2009
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    Fond memories?? For a sampus carnival a friend and I were appointed to make and launch a rocket , stick and paper & 20 sky- rockets each fitted with a U of fine guage NiCr wire. All 20 went off together, and fortunatley no one wat hurt, it was tethered, but it flew round & around.
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    There used to be a 1 1/2 volt dry cell battery called an "igniter cell" It was about 4" across and about 8" tall. It worked fine for rocket motors (using 36 ga wire to set off the charge), and for model airplane glo plugs.
     
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