Burst Disk Pneumatic Q's

[Juggernaut12121]

Alright so ever since I saw Boomer58cal's burst disk cannon I thought about making my own.
My idea was to have a chamber that was made from 2'' by 2' pipe, a 1 1/2'' union, and two barrels, one that's 1'' and another that's a 1 1/2'' golf ball barrel.
My questions are, do I want a bigger chamber? I have some 4'' pipe but the fittings would cost a fortune (for me at least) and I wasn't sure if it would just be overkill since I don't have much experience in this area.
And then if I have a 1 1/2'' union going into a 1'' barrel would the sudden pressure be a hazard in the more confined dead zone between the projectile and the disk?
And finally, how could I break the disk? If I recall correctly Boomer58cal said he just used a bike pump for the final pressurizing but I want something more.... convenient, or trigger like I guess. Like I thought of having an entirely separate chamber that would be connected but sealed from the first, pressurize it at a higher pressure than the first, then use it to gain the extra pressure to burst the disk. But that seemed like too much.

Anyway, thanks in advance to the brilliant minds on this site (far more smarter than I) for any ideas or suggestions

[Boomer58cal]

Alright so ever since I saw Boomer58cal's burst disk cannon I thought about making my own.
My idea was to have a chamber that was made from 2'' by 2' pipe, a 1 1/2'' union, and two barrels, one that's 1'' and another that's a 1 1/2'' golf ball barrel.
My questions are, do I want a bigger chamber? I have some 4'' pipe but the fittings would cost a fortune (for me at least) and I wasn't sure if it would just be overkill since I don't have much experience in this area.
And then if I have a 1 1/2'' union going into a 1'' barrel would the sudden pressure be a hazard in the more confined dead zone between the projectile and the disk?

With a burst disk I would keep my C/B ratio close to 1/1, so how long a barrel are you thinking?

If you want to keep your overall length down 4" would make a huge difference.

And finally, how could I break the disk? If I recall correctly Boomer58cal said he just used a bike pump for the final pressurizing but I want something more.... convenient, or trigger like I guess. Like I thought of having an entirely separate chamber that would be connected but sealed from the first, pressurize it at a higher pressure than the first, then use it to gain the extra pressure to burst the disk. But that seemed like too much.

The only drawback of the CO2 tire inflator is that it needs CO2, and you can find them with a trigger if you like.

To get your larger chamber to smaller chamber idea to work, the larger chamber would need to be several times the size of you small chamber. I've seen it done with both a ball valve and a sprinkler valve between the two chambers. They did work, but used a huge amount of air for their power.

Anyway, thanks in advance to the brilliant minds on this site (far more smarter than I) for any ideas or suggestions

I can already hear the heads inflating over that one. I hope they don't burst.

Whatever method you chose, the hardest thing to avoid with burst disks is that delay between "triggering" your disk and it firing. If you use a 2" ball valve with a small dead space between your chamber and your 1 1/2" disk, the delay should be minimal.

I would use a 2" union because the port in a 1 1/2" union will be slightly smaller than the ID of your gulf ball barrel.

I hope that helps

[Juggernaut12121]

I didn't want to fudge up my over priced barrel too much so I thought of leaving it at it's 5' length, so I'll probably chop up a 2 1/2' section of 4" pipe for the chamber and as for the trigger I might just keep it simple and use a bike pump or my little compressor (if I can find one I'll try out the c02 inflator). As for the union, I'll probably consider stepping up to a 2" union so I can use my 2" barrel that I've never been able to use
Thanks by the way!

[Boomer58cal]

Keep in mind a 5' barrel with any decent valve( or valves for that matter ) behind it will make a golf ball essentially vanish into the sky. With my Trinity cannon and a 5' barrel, at 100+ psi all you see of the ball is a brief glint of sunlight several hundred feet in the air, then its gone. It took about 40 golf balls, three people, a lot of spare time and a phone call from the neighbor to find a ball fired at the maximum pressure. Well over a quarter mile away. And I know it was that far because my property is 1300 feet by 1500 feet and I found the balls well into my neighbors field. hence the phone calls

[Juggernaut12121]

That's what I was hoping to hear
Do you have any damage videos from your trinity cannon? I've seen it a coup of times but was saddened to see no videos or anything like that.

[Boomer58cal]

That's what I was hoping to hear
Do you have any damage videos from your trinity cannon? I've seen it a coup of times but was saddened to see no videos or anything like that.

Thanks for reminding me. I need to shoot some videos next time I take it out. I had issues uploading to YouTube until a few weeks ago, so I'll put one up the next chance I get.

I was going to put a 10 foot barrel on Trinity but I just don't have a long enough range.

If I ever get around to it I'd like to make a Trinity mark II. It would have three 2" valves running through a 3" Cross fitting and out a three inch barrel.

[Technician1002]

Golf balls are quickly lost into the sky when fired from this type cannon. I even tried launching them into a lake and lost sight of it still climbing and didn't see it land in the lake. They just go into the sky, shrink in size and vanish.

[Boomer58cal]

I've been brainstorming about attaching some form of streamers to the ball. Maybe 5 foot of bright red ribbon or something like that.

I had also thought about launching one of these...

[sagthegreat]

paint them with glow in the dark paint, then launch them at night

[Juggernaut12121]

That would look amazing; an unrelated question though, is a C:B of 1:1 the most effective? I've looked around a little bit but didn't find a single thing on pneumatic burst disks' C:B ratio.

I thought of this a little later as well: I'm alright at math but I suck at wrapping my head around some of the figures I come up with.. I have 40" of 4" pipe that I though would be suitable for the chamber, at a C:B of 1:1 (using the formula for the volume of a right cylinder) I got that a barrel at a 2" diameter would have to be nearly 13' long. Is this right or did I fudge up somewhere?

[Boomer58cal]

That would look amazing; an unrelated question though, is a C:B of 1:1 the most effective? I've looked around a little bit but didn't find a single thing on pneumatic burst disks' C:B ratio.

I thought of this a little later as well: I'm alright at math but I suck at wrapping my head around some of the figures I come up with.. I have 40" of 4" pipe that I though would be suitable for the chamber, at a C:B of 1:1 (using the formula for the volume of a right cylinder) I got that a barrel at a 2" diameter would have to be nearly 13' long. Is this right or did I fudge up somewhere?

I got roughly 13.3 feet.

[Juggernaut12121]

Then I'm going to need to buy a new barrel
Sorry for all of the questions but, with such length I thought of getting two 4" elbows and making it an under over style cannon, but I was afraid of losing power. How much power would this eliminate from the cannon, and is I used 2" elbows instead would that be a noticeable decrease?

[Boomer58cal]

Then I'm going to need to buy a new barrel
Sorry for all of the questions but, with such length I thought of getting two 4" elbows and making it an under over style cannon, but I was afraid of losing power. How much power would this eliminate from the cannon, and is I used 2" elbows instead would that be a noticeable decrease?

As long as the elbows are part of the air chamber and not part of the barrel you shouldn't notice much difference in power.

No worries about all the questions, I've been planning something similar myself.