New Combution Cannon!

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.
User avatar
brplatz
Specialist 2
Specialist 2
Posts: 222
Joined: Fri Mar 21, 2008 12:21 am

Thu Apr 17, 2008 4:44 pm

here is my new cannon. took about 2-3 days and multiple Lowe's runs to get er' done. Paint coming soon. 70"by 2" barrel and about a 20" Chamber. spark strip, chamber fan and Grill ignitor.

Almost done!

Image
Image
Image
"Any problem on Earth can be solved with the careful application of high explosives...the trick is, not to be around when they go off" Col. Mertz Von Quiriheim
User avatar
STHORNE
Sergeant 3
Sergeant 3
Posts: 1208
Joined: Wed Feb 14, 2007 7:50 pm
Location: Kewaunee, Wisconsin

Donating Members

Thu Apr 17, 2008 4:46 pm

wow, very nice job. damage pics?
Forum Rules - follow them or else!
“Happiness is the meaning and the purpose of life, the whole aim and end of human existence”
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 Apr 17, 2008 6:14 pm

Looks like a powerful cannon you have there...lots of chamber, lots of barrel...metered fueling...nice effort!

You should get yourself back down to Lowe's one more time and pick up some hose clamps to replace that duct tape. Also, it looks like you have forever sealed your spark system and fan inside your chamber with no way to service them if needed. Something to keep in mind for future combustions.

Have you shot the thing yet?
User avatar
bigbob12345
Staff Sergeant
Staff Sergeant
Posts: 1516
Joined: Sat Dec 01, 2007 9:13 am
Location: Mercer Island,Washington

Thu Apr 17, 2008 6:20 pm

Great job
And cool ball valve, where did you get it
User avatar
STHORNE
Sergeant 3
Sergeant 3
Posts: 1208
Joined: Wed Feb 14, 2007 7:50 pm
Location: Kewaunee, Wisconsin

Donating Members

Thu Apr 17, 2008 6:37 pm

yeah man...thats about the most unique ball valve i've ever seen (never seen it b4).

I haven't seen them at lowe's, so you got them somewhere else?
Forum Rules - follow them or else!
“Happiness is the meaning and the purpose of life, the whole aim and end of human existence”
User avatar
brplatz
Specialist 2
Specialist 2
Posts: 222
Joined: Fri Mar 21, 2008 12:21 am

Thu Apr 17, 2008 6:52 pm

@starman
thanks i plan to get that duct tape off of there but it was much better that the bulky wood supports i made before. And no i have not been able to get it to fire yet. one calculator said about 85 PSI with my metering system but it didn't ignite. i must have tried it 5-6 times. so i tried another calculator and it gave me 50 psi to put in but i haven't tried it yet.

the ball valve you see there is one i found at Lowes right next to the one like http://img.diytrade.com/cdimg/430486/40 ... 526668.jpg

i had one like that but it was a B!&@% to open and close. so i found this one and it is extremely easier.

COST me $90 bucks to make ugh! most expensive for me yet lol. Where can i get new propane tanks like the one pictured? i found that one in a cabinet in my garage lol
"Any problem on Earth can be solved with the careful application of high explosives...the trick is, not to be around when they go off" Col. Mertz Von Quiriheim
User avatar
brplatz
Specialist 2
Specialist 2
Posts: 222
Joined: Fri Mar 21, 2008 12:21 am

Thu Apr 17, 2008 9:26 pm

anyone have an opinion on the PSI i should inject the propane at that would be great!

thanks

EDIT: forgot about double post sorry
"Any problem on Earth can be solved with the careful application of high explosives...the trick is, not to be around when they go off" Col. Mertz Von Quiriheim
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 Apr 17, 2008 9:36 pm

brplatz wrote:anyone have an opinion on the PSI i should inject the propane at that would be great!
Be sure you are taking into account the volume of your rear elbows as part of the tank volume...all the way around to the potato breech. Also, your meter looks a tad bit smallish for your tank size, just eyeballing it from here...even using 1/2" pipe..maybe not. Check that again. If not you should have to be running a fairly high meter pressure to get the right amount. Check out Pat123's meter calc here:

http://www.spudfiles.com/forums/viewtop ... tml#169995

ALSO, one ugly thing I just noticed. You've got your propane tank mounted where it will essentially be upside (or tilted downward) most of the time...not good, will tend to liquidize and "flood" your meter plumbing. Turn it around the other way.
Last edited by starman on Thu Apr 17, 2008 9:57 pm, edited 2 times in total.
User avatar
brplatz
Specialist 2
Specialist 2
Posts: 222
Joined: Fri Mar 21, 2008 12:21 am

Thu Apr 17, 2008 9:47 pm

i tried it at 90 psi and nothing. im thinking my spark system is failing. i might have to go get a more powerful ignitor like a stungun and such.

the Propane tank is like that just for the pictures. its usually the other way around.

Image
"Any problem on Earth can be solved with the careful application of high explosives...the trick is, not to be around when they go off" Col. Mertz Von Quiriheim
User avatar
DYI
First Sergeant 5
First Sergeant 5
Antigua & Barbuda
Posts: 2862
Joined: Sat Jul 07, 2007 8:18 pm
Location: Here and there

Thu Apr 17, 2008 9:48 pm

Just take the 5 minutes and do the meter calculations yourself. It won't kill you, and it might do a lot more good than all these "calculators" people are using.
Spudfiles' resident expert on all things that sail through the air at improbable speeds, trailing an incandescent wake of ionized air, dissociated polymers and metal oxides.
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 Apr 17, 2008 9:51 pm

brplatz wrote:i tried it at 90 psi and nothing. im thinking my spark system is failing. i might have to go get a more powerful ignitor like a stungun and such.

the Propane tank is like that just for the pictures. its usually the other way around.
OK I get you on the upside down tank...hose is a bit long then. Also check with the calculator I edited into my last post.

Also, you should be able to hear a spark in there...and see one if you open the rear intake valve. Make sure you air it out good first... :roll:

IMO, it's hard to beat a stun gun for advanced combustions...
User avatar
BlackH
Private 4
Private 4
Posts: 73
Joined: Thu Feb 01, 2007 7:24 am
Location: Cape Town, South Africa

Fri Apr 18, 2008 1:46 am

Yes lose the calc go to http://www.burntlatke.com/lp.html here is all the stuff you need to work out the stuff.

And here is a spark strip i made myself that has never let me down.

http://www.spudfiles.com/forums/my-new- ... 14078.html

O ps I don’t know if those gas bottles you use (I could not find a tap fitting for them here in SA) can work upside down make sure you hold the gas bottle upright if you load, I had that prob. and it floods your meter system. (This happened to me and uses a lot of gas.)
User avatar
brplatz
Specialist 2
Specialist 2
Posts: 222
Joined: Fri Mar 21, 2008 12:21 am

Fri Apr 18, 2008 7:55 am

ok burnt latke gave me a Psi of about 53 so ill try that today. i was hitting 90ish on my first attempts. Burnt Latke has some great info and tools!

i make the spark strip like yours but less gaps because its just a regular BBQ lighter. im thinking i dont have enough power to jump the gaps. ill see if i can go find a electronic one or a stungun somewhere also.
"Any problem on Earth can be solved with the careful application of high explosives...the trick is, not to be around when they go off" Col. Mertz Von Quiriheim
User avatar
stevenarroyo
Specialist
Specialist
Posts: 155
Joined: Sun Jul 27, 2008 7:50 pm
Location: Miami, FL
Contact:

Fri Aug 01, 2008 4:08 pm

damn i have to see what that cannon can do!!

show us some more pic's plz
Post Reply