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RC Rocket Pod

Discussion in 'General Electronics Discussion' started by eXodus, Feb 17, 2012.

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  1. eXodus

    eXodus

    6
    0
    Feb 17, 2012
    I have been dared to build rocket pods for my RC Aircraft. Given my programming background, I'd need a little help with electricity and electronics.

    What I know so far is :
    • I have 1 channel to use as a fire signal
    • I would like 1 firework to fire per signal-on event
    • I would use side-by-side bottle rockets (2-4 per wing) to keep this safe
    • I would like 2 rocket pods (1 under each wing)
    • I would like to alternate from each pods when firing
    • A wireless bridge between the plane's radio receiver and the pods would be awesome although not required.
    • All this has to be lightweight (~1 lbs?). It is a big craft, twin electric fans.

    I know this is a big project, especially for a programmer, but I like challenges.

    Could somebody help me with the circuit design and the ignition system?

    Thanks
     
  2. eXodus

    eXodus

    6
    0
    Feb 17, 2012
    Here is what I came up with. There are a few details I'd need help to figure out. They are in red in the following schematics.

    Pods.png

    An easy one for non-beginners would be to connect the LED showing if the circuit is live or not.

    My main concern though, is the "automatic switch" in the middle. Does such a device exist that would automatically switch its output destination?

    Thanks
     
  3. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    Hi exodus
    welcome to the forums :)

    Altho I cant directly help you on all of the needed circuitry, I have done some redrawing of
    the one you supplied and fixed some wiring errors and added the ignition power on LED for you :)

    [​IMG]

    cheers
    Dave
     

    Attached Files:

    • Pods.png
      Pods.png
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  4. eXodus

    eXodus

    6
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    Feb 17, 2012
    Thanks for the LED. I always tought current was going one way or the other. I guess adding a resistor allows the remainder of the current to flow through the circuit when a relay is closed.

    For the switching output, I've been told to look into Arduino boards. They seem pretty easy to program too.

    Someone here have experience with such boards and know about pitfalls to avoid?
     
  5. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    The resistor limits the current through the LED stopping it from burning out

    cheers
    Dave
     
  6. jackorocko

    jackorocko

    1,284
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    Apr 4, 2010
    Actually the arduino is really easy to use. But can be bulky if space is an issue, there are ways to shrink down the physical size once you have the code you need. There are also different variations on the basic arduino that might interest you. Like the nano http://arduino.cc/en/Main/ArduinoBoardNano What languages do you program in?
     
  7. jackorocko

    jackorocko

    1,284
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    Apr 4, 2010
    I got just one question though, wouldn't it make the plane very unstable to only fire a rocket on one side of the plane? It would make less of an impact the closer the rocket is to the fuselage, but then you have to worry about setting the thing on fire.
     
  8. eXodus

    eXodus

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    Feb 17, 2012
    Nice, I didn't spot this variant. Space is indeed an issue, as well as weight and power consumption.

    Being a programmer, I don't mind which language it is using. I suppose it uses a C-like language, which I'm already proficient with. If not, I'll learn it on the fly. In the end I'm only going to do an increment and a modulo and send an output signal for which there should be a provided API.
     
  9. eXodus

    eXodus

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    0
    Feb 17, 2012
    That is why I'll be using bottle rockets (that and overall safety). They don't kick very much, so it shouldn't be any harder on the plane than common turbulence. I'm also concerned with fire though. I think I will line the interior of the pod with glass fiber cloth.
     
  10. Raven Luni

    Raven Luni

    798
    8
    Oct 15, 2011
    If you want to save money on those electric match things consider using a low value resistor and grossly exceeding its power rating - should burst into flames :)
     
  11. eXodus

    eXodus

    6
    0
    Feb 17, 2012
    Does it take much time to burn?

    My current solution was to attach a fast burning fuse to the tungsten inside a detachable Christmas light and mount it at the bottom of the bottle rocket. This way I can fix the sockets at the bottom of the Pod and have an easy way to reload.

    Lights like these

    [​IMG]
     
  12. twister

    twister

    172
    7
    Feb 12, 2012
    I think a 4017 would work for this. It is a decade counter divider that will change it's output with each pulse. On the forth output pin you would hook to the reset pin. A 4017 can be used to divide by any number up to 10.
    A NTD3055L mosfet transistor could be used to fire the match.
    You can buy nicrome wire and make your own matches. You take a book match head and split it and place the wire inside of the split.
    Very interesting project. I hope to hear how it works out.
    Here is some data on 4000 series ICs.
    http://www.kpsec.freeuk.com/components/cmos.htm#4017
     
    Last edited: Feb 20, 2012
  13. twister

    twister

    172
    7
    Feb 12, 2012
    That seemed like a good idea you had, so I tried it. With a 1 ohm resistor, it simply opened. With a 5 ohm it worked great! With a 12V battery it used 2.5 amps. Trouble is it took a couple of seconds to open. This probably would not work with a 9V battery.
     
  14. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    You aren't gonna get anywhere near 2.5A from a 9V battery.
     
  15. Raven Luni

    Raven Luni

    798
    8
    Oct 15, 2011
    Try a lower watt rating and/or a bank of D cells.
     
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