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Thread: Need advice: Building fireworks mortar/canon

  1. #1
    Boolit Master
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    Lightbulb Need advice: Building fireworks mortar/canon

    So I buy these 60gram 5" mortars for the holidays. They come with fiberglass mortar tubes. The trouble is I'd like to fire these mortars higher. I'd like to get them twice as high, if possible, but even 25-50% higher would be good. I'm thinking this might be possible by using a longer tube and maybe a larger powder charge. Obviously, I'm limited by the delay fuse length, but I'm willing to bet there's still plenty of room for optimizing the launch.

    I'm thinking of buying some super-heavy gauge steel tubing, say, 1" thick walls, and double or tripple the length of the original fiberglass tube. Same bore diameter, which is pretty loose. I figure on tack-welding a steel plate as the bottom of the tube. I'd rather the welds break than the tube explode.

    But, I might be way off base on all this. Please guide me to success.

  2. #2
    Boolit Man Alasgun's Avatar
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    “Success” would be leaving well enough alone!!

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    Winger Ed.'s Avatar
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    It's not so much the length of the tube that determines how high the shell goes up.
    It's the lifting charge in the firework itself.

    You can play around adding to the lifting charge, but the shell is designed for what it comes with.
    Just adding to the lifting charge will probably shatter the container that holds the rest of the shell together.
    If that happens, it'll probably burst as it comes out the tube.

    Like the difference in a couple of inches of barrel length is related to a bullet's velocity-
    you might gain a little with a longer tube, but not much.
    In school: We learn lessons, and are given tests.
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    Boolit Buddy super6's Avatar
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    HDPE pipe is what you need, Glue and screw a 3'' wood block in the bottom. Build a rack to stabilize, Go with a 3' length and shoot to 500'. I use 3/8 wall tubing. And use a peace of chicken fuse!
    Last edited by super6; 07-21-2022 at 01:00 PM.
    takeo Shimizu , The father of organic chemistry

  5. #5
    Boolit Master
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    That's an interesting idea, Super6. I especially like the idea of a wood bottom plug, for safety. You think HDPE pipe is strong enough? What kind of lifting charge do you use?

    Winger Ed, you're probably right about the firework canister having a design limit. I'm betting there's some room to play with though. I mean to experiment with fail-safes in place.

  6. #6
    Boolit Master Hannibal's Avatar
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    This thread reminds me of a saying I first heard a very long time ago.

    'There are old mushroom hunters and there are bold mushroom hunters. But there are no old, bold mushroom hunters.'

  7. #7
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    GregLaROCHE's Avatar
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    Thé size pipe you’re talking about sounds like a canon. Load it with BP and toilet paper and let it rip! It’s only going to make a Big Bang, but that’s what a lot of the fun is about.

  8. #8
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    Winger Ed.'s Avatar
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    Quote Originally Posted by Oreo View Post
    I'm betting there's some room to play with though. I mean to experiment with fail-safes in place.
    Don't shoot your eye out kid!
    In school: We learn lessons, and are given tests.
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    EVERYONE!
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  9. #9
    Boolit Master Sasquatch-1's Avatar
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    It seems to me that the timing for the burst is set so the shell explodes as it reaches a certain height. Any change in the lift really wouldn't be realized due to the shell exploding while still rising. You may get a couple feet at most.
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  10. #10
    Boolit Grand Master Nobade's Avatar
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    Quote Originally Posted by Sasquatch-1 View Post
    It seems to me that the timing for the burst is set so the shell explodes as it reaches a certain height. Any change in the lift really wouldn't be realized due to the shell exploding while still rising. You may get a couple feet at most.
    My thoughts exactly. No way to lengthen the delay.

  11. #11
    Boolit Master
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    What are you using for a lifting charge, right now? Is it likely that it burns faster than Fg grain gunpowder? IF it burns faster than Fg, then adding length to the "tube" (therefore increasing combustion time) may not gain you much altitude. IF Fg burns more slowly than your current lifting charge, then using Fg in a longer "tube" MAY give you higher velocities (therefore altitudes), in much the same way that longer-barreled firearms tend to exhibit higher velocities than shorter-barreled firearms (all other factors being equal).
    Not seeing what equipment you are working with, it all sounds rather unduly dangerous. Then again, sometimes valuable knowledge comes from "for Spits & Giggles" experimentation.
    For in much wisdom is much grief: and he that increaseth knowledge increaseth sorrow. Ecclesiastes 1:18
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    Boolit Buddy super6's Avatar
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    Quote Originally Posted by Oreo View Post
    That's an interesting idea, Super6. I especially like the idea of a wood bottom plug, for safety. You think HDPE pipe is strong enough? What kind of lifting charge do you use?

    Winger Ed, you're probably right about the firework canister having a design limit. I'm betting there's some room to play with though. I mean to experiment with fail-safes in place.

    If you are using ball shells, HDPE is plenty strong enough, Cylinder shells not so much, May be two break at most otherwise use steel pipes and bury them. You did not say if you are planning to build your shells? If so time fuse or a spoolet will solve the time issue. Heavier granulation's of black powder will smooth out the pressure spike.
    takeo Shimizu , The father of organic chemistry

  13. #13
    Boolit Master
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    They are 5" & 6" long cylinder shells that I buy. I don't make my own, but I was figuring on cutting the lift charge open to repackage a larger charge. I hadn't really settled on how to handle that yet, actually. I have no idea what the manufacturer used in there, but I guess I'll have to find out.

    The timing of the shell is a simple burning fuse. It doesn't care what altitude it's at. My goal is to get a higher muzzle velocity so the shell reaches a higher altitude before the delay fuse is exhausted.

    I'm using ones like these:
    Name:  ox318-ragingbullartillery6.jpg
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  15. #15
    Boolit Buddy super6's Avatar
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    ^^^ this So.. Your talking about 2-3" shells ? No need for the steel.
    Last edited by super6; 07-22-2022 at 02:12 PM.
    takeo Shimizu , The father of organic chemistry

  16. #16
    Boolit Master
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    Hey, hold my beer and watch this can have many outcomes. In my circle there is a shed the entire side was replaced due to a "failed launch", it appears tighter and longer did not equate to velocity and height in this instance. There was red, blue and gold things blazing between us, through our legs and by our heads and unbelievably not one burn. But boy howdy, not no but Hell no never again. My suggestion would be spend a little more for the ones that do what you want. I know, where is the fun in that, hey, hold my beer!

  17. #17
    Boolit Grand Master jmorris's Avatar
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    You could go extra dangerous and make a sabot for your tube and shoot the whole thing up in the air before it goes off.


  18. #18
    Boolit Grand Master jmorris's Avatar
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    Saw dust and a road flare makes a pretty huge mushroom fireball, I made a “trigger” so I could be hundreds of feet away though.


  19. #19
    Boolit Master elmacgyver0's Avatar
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    Fireworks were recently legalized in Iowa; I am more than satisfied with what I can buy at the local stands.
    Being in my 70s it is a bit too little too late, but I still enjoy them, my wife says I have the mind of a 12-year-old.
    The local authorities, being a bunch of *******s reduced the time we can shoot them off to July 3rd & 4th and only 5pm to 10pm.
    I mean ***! the Fourth only comes around once a year! All the liberal little old ladies complain they can't sleep, more likely they like to make people miserable.
    Anyway, I hope you are not one of these guys on U-Tube firing bottle rockets from their butt crack, not a pretty picture, but I still laughed like hell.
    I wonder what the ER people thought?

  20. #20
    Boolit Master


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    Might want to check with the local federals, laws varies from state to state. A good friend of mine who made fireworks of real quality, professional grade stuff. Used to go to firework "shows" where you could acquire your supplies and most importantly learn how to make fireworks. After 30 years of making fireworks, he had a test mortar get away from him and put a star into his 125 x 100 pole barn, chocked full of commercial made fireworks and stuff he made and stored (For people that don't have a license, current law states you can make fireworks, but it can't leave the property and it has to be displayed the day it was made) This got him into trouble later. The resulting explosion and fire completely destroyed his barn and a good deal of farm equipment stored therein. The ATF tried to charge him with domestic terrorism, he was 70 at the time. He ended up beating all the charges but it took two years and a wheelbarrow of cash.
    Were me, I think I would be happy with what you can purchase. Just my opinion.
    Before you embark on a journey of revenge, dig two graves.”

    ― Confucius

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