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Explosions without fire?

Discussion in 'Special Effects' started by Conner8809, Aug 25, 2008.

  1. Conner8809

    Conner8809 Member

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    Well i have a heck of a problem for you guys here at CB. I am doing the show You Can't Take it with you. There are several explosions that happen right on stage infront of the audience, we are not allowed to have an open flame on stage. i was thinking some sort of dry ice bomb in a sealed film canister? You guys are much more creative than me. So help a guy out!
     
  2. LightStud

    LightStud Active Member

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    Absolutely NOT to the "dry ice bomb!"

    Buy an air compressor, locate it as far away from stage as possible (preferably in another room), a long hose and a solenoid-controlled air valve, ala confetti cannons. Use of pneumatics is the only acceptable way to make an explosion other than pure mechanical effects (springs?). Nothing else is consistent or reliable enough. Even with pneumatics, Safety is still critical. Use the lowest possible pressure to achieve the effect desired. You could put an eye out, or worse! Make all "shrapnel" out of foam rubber. I seem to recall all explosions taking place "offstage" beyond the basement door when I did YCTIWY, but we did use pyro for the flash and bang.
     
    Last edited: Aug 26, 2008
  3. TimMiller

    TimMiller Well-Known Member

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    dry ice bombs are cool, but very dangerous. They are not safe, or reliable. The best way is using the confetti cannon trick. Basically you get an air compressor, or just an air tank, stright off the air tank you connect up a soleniod (using 1" pipe), then from the soleniod to a piece of PVC pipe. The PVC Pipe should be at least 2" and make it at least a foot long. Also for something more heavy duty you can use metal pipe, which i would personally perfer, it will not crack or blow apart. The longer the pipe the deeper the boom. Wire the soleniod up to a push button and fire it. I know about 90 PSI will make a pretty good sized boom. Do not exceed 125 PSI for air operated devices.
     
  4. codered11343

    codered11343 Member

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    Back when I was in high school we did a production of Peter Pan (the play) and we needed to replicate some cannons going off. I don't remember all the details, but we used a small device (about the same size as a deck of cards...more or less) that were placed on stage with a wire running to a switch off stage. When they were triggered it caused a bright flash, a very loud "banging" noise and a clouds of smoke. But I do not know were you would be able to get them or even what they are called.
    I will do a little asking around and see what they are and were you may be able to get them, but I believe that are safe because it was just high school students that were running them.
     
  5. Conner8809

    Conner8809 Member

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    would it be possible to simulate firecrackers using a bunch of small pipes and instead of it going BOOM it goes crack, crack, crack? also where could i find a inexpensive solenoid. while safety is my first concern. we have 700$ as a budget as of now. hehe. this may not go over so well.
     
  6. codered11343

    codered11343 Member

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    do you mean just hitting steel pipes together from off stage?
     
  7. Conner8809

    Conner8809 Member

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    no i meant using a solenoid
     
  8. Sayen

    Sayen Active Member

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    I did this show two years ago on a tight budget. We took a party-grade fog machine, a cheepie from a local party store, pumped smoke into a trashbag. For the effect, we played a loud explosion over a backstage speaker, the door from the basement pushed open a bit, and then squeeze the smoke out of the bag. Quick, fast, and convinced the audience. Bits of flying rubber would have made a fun addition.
     
  9. jwl868

    jwl868 Active Member

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    Do not use PVC for compressed air piping. (You will find this warning at all PVC vendors product sheets. See for example, Nibco-Chemtrol.) Oil that is often found in air compressor discharges will weaken the PVC. When PVC pipe fails, it splinters and creates flying shards. (The big tube "gun" part is probably okay because it is open-ended – as long as no one does anything stupid.)

    Make sure the rest of the parts (valves, fittings, and hoses) are rated for compressed air and the maximum pressure that the system might be subjected to.

    Joe
     
  10. cdub260

    cdub260 CBMod CB Mods

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    We had a firecracker effect in last year's Pageant. We used, American DJ Flash Rope, and stapled 8 of them to an 8 ft. long 1x12 board. We used 4 dimmers to power the effect, via a linked cue sequence, with sections of the board powering up in sequence, starting at the bottom, and working up to the top. This was paired with a firecracker sound effect. While it wasn't perfect, as Flash rope cannot be set to fire in sequence, it did a pretty good job of simulating firecrackers. The most difficult part of this was synching the light and sound cues, and even that wasn't too hard.

    A google search for American DJ Flash Rope yielded more potential suppliers than I cared to sift through, but the average price I saw was about $80.00 a piece. I would, however recommend using a cable tacker or some other cable fastening device to install the Flash Rope. You should be able to find something at your local hardware store. If you don't have the dimmers available, look into renting some variation of a backpack dimmer from your local supplier.

    Oh, and before I forget, Flash Rope is a strobe effect, so you will need the appropriate signage posted at your venue.

    Hope this helps.
     
    Last edited: Aug 26, 2008
  11. lieperjp

    lieperjp Well-Known Member

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    Safety is more important that a cheap fix that could hurt, permanently injure, or kill someone. If you don't have the money, tell the powers that be to either give you more money or they can pay the medical bills and high insurance premiums that may result from a cheap fix gone bad.
     
  12. Van

    Van CBMod CB Mods Premium Member

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    I think the basics have all been covered; here's some cost-cutting techniques. If you can't afford the solenoid option for the confetti cannon idea, then simply use a blower valve to run it manually. If the area is kept clear you can use Rye Flour in the tube as a smoke / dust effect. Rye Flour seems to be the most hypo allergenic, and Equity-approved way of making good dust on stage. I don't recommend anyone walking into a thick cloud of it, but if they do it's much less likely to cause any issues than any other powered material.

    Important Safety Tip: If you are using anything for a dust effect, DO NOT USE TALCUM POWDER. It's very dangerous to breathe; Talc and Asbestos come out of the same mines. Use either corn starch, or rye flour; as mentioned above you'll find rye flour to be even more hypo-allergenic than corn starch.
     
    Last edited by a moderator: Aug 26, 2008
  13. icewolf08

    icewolf08 CBMod CB Mods

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    We did this show two seasons ago. Our TD and special effects engineer had a "blast" cannibalizing Nerf guns so that we could hook them to our air compressor and shoot the rockets through the door. We also rigged the door to be able to release from the wall and fall over. We used a fogger and a strobe to get some flashes and smoke. The whole sequence was tied together with sound effects. It worked quite well.

    Rye flour is also one of the best to use to make your own sourdough starter!
     
  14. Conner8809

    Conner8809 Member

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    Incredible ideas. I spoke with my director today and she asked if it would be possible to somehow put the "firework" onstage, there are no blackouts near it so an actor would have to bring it in.
     
  15. cdub260

    cdub260 CBMod CB Mods

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    PM me if you need any more advice, and I'll try to go into a little more detail.
     

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