Great Idea, I cant find anyone that has tried it !

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
Rob748
Private 4
Private 4
Posts: 84
Joined: Wed Feb 18, 2009 9:44 pm

Wed Mar 18, 2009 9:10 pm

So I was on Hgdt running some simulations on my advanced combustion gun thats only has a end coupler and ball valve on it so far...... I found that I needed a 10 foot barrel for a .8:1 ratio, and I had this great Idea, id split the barrel into multiple parts via unions, this would allow for multiple barrel lengths, and Multiple burst disks. My first union would come directly out from the chamber, this would be the first burst disk and a optinal barrel length for noise making, Then after the first union, 5 inches after it, I would have another union , with another Burst Disk. With these to unions and burst disks, comes a handy chamber to hold smaller projectlies, 5 feet from the last union would be the last union and burst disk, Giving me a interechangle barrel lenth from one pipe. Just a union/burst disk and no other piping would be for noise making, and the union in the middle of the chamber could be for loud yet somewhat fast projectiles, and the whole barrel together for long distance. But here comes a question, Lets say my first burst disk fails at 50 psi, my 2nd one fails at 65 and the last fails at 75, Or vice verca, what would multiple burst disks do ?, would it be a increase in Loudness ?
User avatar
Radiation
Specialist
Specialist
Posts: 183
Joined: Wed Jul 09, 2008 10:57 am

Wed Mar 18, 2009 10:46 pm

I don't think you understand how a burst disk works. If you tried what your saying here you would find that your projectile woulld get stuck somewhere in the barrel.
Last edited by Radiation on Wed Mar 18, 2009 10:50 pm, edited 1 time in total.
I void warranties.

The Gauntlet of Clara Ann
User avatar
mark.f
Sergeant Major 4
Sergeant Major 4
Eritrea
Posts: 3627
Joined: Sat May 06, 2006 11:18 am
Location: The Big Steezy
Has thanked: 52 times
Been thanked: 53 times
Contact:

Donating Members

Wed Mar 18, 2009 10:48 pm

Radiation is right. A projectile catching on one of these fittings (especially the furthest one) has the potential to rip your barrel to hell and gone. It's one thing to say "Sure, it's safe because they're pressure rated", but they're definitely not rated for projectiles hitting them at about 300 fps. :wink:
Rob748
Private 4
Private 4
Posts: 84
Joined: Wed Feb 18, 2009 9:44 pm

Wed Mar 18, 2009 10:53 pm

I understand how a burst disk works, I might have not been clear enough in my post what I mean is, One the first layer is broke that would begin moving the proectile, now the pressure is at the second burst disk and the projectile is at the second burst disk, now it has to overcome the second obstalce and once it does overcome it is should ram through the last disk with ease.

So what you guys are saying is that the projectlie will catch on a union ?

Edit by jrrdw.
User avatar
Radiation
Specialist
Specialist
Posts: 183
Joined: Wed Jul 09, 2008 10:57 am

Wed Mar 18, 2009 11:02 pm

It doesn't work that way your burst disk only works if it's between the chamber and the barrel. In your example the projectile is on the wrong side of the disk. Also burst disks take quite a bit of energy to burst. If you put multiple disk seperated by different lengths you would get diminishing return because you are expending slot of energy every time a disk bursts.

Edit: now that's not to say you can't split the barrel, I have done this but you may blast off part of your barrel. It may break or it may just seperate.
I void warranties.

The Gauntlet of Clara Ann
Rob748
Private 4
Private 4
Posts: 84
Joined: Wed Feb 18, 2009 9:44 pm

Wed Mar 18, 2009 11:06 pm

What about no projectile ?, would it be a sound maker ? or should I just forget the multiple burst disk idea lol
User avatar
Radiation
Specialist
Specialist
Posts: 183
Joined: Wed Jul 09, 2008 10:57 am

Wed Mar 18, 2009 11:12 pm

Yeah you should just drop the multiple disk idea. If you want a louder bang you need a burst disk that bursts at a higher psi (assuming your cannon can perform at a higher psi) and no barrel. Remember louder does not mean you have a more powerful gun, it means you have a highly inefficient gun that is losing a lot of energy to an unfocused blast. A longer barrel is more efficient, more powerful (to a point) yet much more quiet.
I void warranties.

The Gauntlet of Clara Ann
Rob748
Private 4
Private 4
Posts: 84
Joined: Wed Feb 18, 2009 9:44 pm

Wed Mar 18, 2009 11:25 pm

Is there a way that I can have a splittable barrel ? delete
Last edited by Rob748 on Thu Mar 19, 2009 1:57 pm, edited 1 time in total.
User avatar
mark.f
Sergeant Major 4
Sergeant Major 4
Eritrea
Posts: 3627
Joined: Sat May 06, 2006 11:18 am
Location: The Big Steezy
Has thanked: 52 times
Been thanked: 53 times
Contact:

Donating Members

Wed Mar 18, 2009 11:28 pm

Take a look at BurntLatke, in the breech loading section.
User avatar
starman
Sergeant Major
Sergeant Major
United States of America
Posts: 3027
Joined: Wed Dec 12, 2007 12:45 am
Location: Simpsonville, SC

Donating Members

Thu Mar 19, 2009 4:17 am

I'm still puzzled why you are still chasing this multiple burst disk thing. I actually have some ideas around how to use a second burst disk effectively but not in the context you are describing.
Rob748
Private 4
Private 4
Posts: 84
Joined: Wed Feb 18, 2009 9:44 pm

Thu Mar 19, 2009 1:31 pm

Hows that starman ?
Rob748
Private 4
Private 4
Posts: 84
Joined: Wed Feb 18, 2009 9:44 pm

Thu Mar 19, 2009 2:00 pm

yeah thats what I thought ?
User avatar
starman
Sergeant Major
Sergeant Major
United States of America
Posts: 3027
Joined: Wed Dec 12, 2007 12:45 am
Location: Simpsonville, SC

Donating Members

Thu Mar 19, 2009 2:43 pm

Rob748 wrote:Hows that starman ?
Just ideas, interesting cool sounding ones, very unproven, not willing to stake reputation on at this point kind of ideas.... 8)
Rob748
Private 4
Private 4
Posts: 84
Joined: Wed Feb 18, 2009 9:44 pm

Thu Mar 19, 2009 2:44 pm

well I might be interested in trying one of ur ideas....... lol
User avatar
starman
Sergeant Major
Sergeant Major
United States of America
Posts: 3027
Joined: Wed Dec 12, 2007 12:45 am
Location: Simpsonville, SC

Donating Members

Thu Mar 19, 2009 2:51 pm

Rob748 wrote:well I might be interested in trying one of ur ideas....... lol
Maybe you would, but not until after I try it first my man... 8)
Post Reply