Remote Ignited DWV Advanced Combustion

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.
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bigbob12345
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Fri Jun 20, 2008 11:32 am

Well here is an advanced combustion I recently made out of mostly recycled parts.
I call it Remote Ignited DWV Avanced Combustion or RIDWVAC for short

Pic with no barrel on
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Well as you see it is DWV, this is why I "remote fire" it. It is all solid core DWV ABS except for the barrels, one is cell core abs and the other is sdr21 pvc.
Well I wouldnt really say that it is a true remote igniting system, its just some extended wires attatched to an electric BBQ ignitor. I stand back 5-10ft when I fire it, or just hide behind something.
I also pressure tested the chamber to 180psi(remotely) and it didnt burst, crack, or leak. I thought I would feel safe firing it in my hands if it survived that but I didnt, and settled on a remote ignitor.

And I bet all of you are thinking OMGWTFBBQ BIGBOB IS A HIPPOCRIT!!!1!!1!!ONE!!1!. Well, I guess I sort of am. I scold people for using dwv and then I build one out of DWV for my self.
But I had almost all these parts already and coulntnt resist a $10 advanced combustion.

Im going to build a similar one out of pressure rated pvc in a week or two so I can actually fire it in my hands and feel the recoil.

OK, thats enough of the DWV stuff, im now actually going to start talking about the gun itself.

Well, it has a propane meter, double gap igniton, and a good chamber to barrel ratio. the only thing its missing is a chamber fanand a pressure rated chamber. Well, I couldnt be bothered to put one in a gun that is only temporary. I guarrentee you that my pressure rated one will have one though.

Spec time

Chamber: 12in of 3in solid core DWV ABS
Barrels:50in of 1.5in sdr21 and 52in of 1.5in cell core abs
ignition: electric BBQ ignitor wired so It can be fired up to ten feet away
CB: GB barrel: .75:1, Potato Barrel: .8:1

Video time

[youtube][/youtube]


and some more pics

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and thats it
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SpudFarm
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Fri Jun 20, 2008 11:39 am

cool gun.

sems like it has some kick to.
"Made in France"
- A spud gun insurance.
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bigbob12345
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Fri Jun 20, 2008 12:01 pm

Thanks
And it has a lot of kick because it is very light.
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Spuddin
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Fri Jun 20, 2008 12:11 pm

aint those electric bbq sparkers great, i just started using one and i love it. btw your gun would be a perfect drain pipe test gun to see how long it can take the pressure. good idea on the remote ignition, safety first..
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starman
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Fri Jun 20, 2008 12:40 pm

That sparker actually looks like it's got stungun guts...would make sense.

I would be a little leary stretching that High V out like that. I'm sure that voltage can easily arc through that standard insulation. Closing your spark gaps down some will help prevent the arcing outside the gun.

This is good for a test project...now build that pressure rated one... :wink:
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SpudFarm
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Fri Jun 20, 2008 1:39 pm

starman wrote: I would be a little leary stretching that High V out like that. I'm sure that voltage can easily arc through that standard insulation. Closing your spark gaps down some will help prevent the arcing outside the gun.
i have used an ignition coil and camera cap through 1mm speaker wire and it works nice.
"Made in France"
- A spud gun insurance.
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iPaintball
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Fri Jun 20, 2008 2:02 pm

Nice gun, although it's really not necessary to remote fire it... IIRC combustion guns only produce between 60 and 80 psi for a very short period of time. Even if for some reason this gun were to rupture, it would only tear the ABS.
Summer Projects:
CO2 tank hybrid: Gotta fix the meter :(
Cane gun: Needs a pilot/fill setup
1.5" piston valve gun: Almost done
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SpudFarm
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Fri Jun 20, 2008 2:14 pm

agree. you saw how much DYI's barrel took.
"Made in France"
- A spud gun insurance.
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bigbob12345
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Fri Jun 20, 2008 2:22 pm

Spuddin: Yeah they are great
They are cheap(relitively), easy to get hold of, and effective.

Starman: Yep it sparks through the wire like it isnt even there.
I just had a bunch of this stuff laying around and could be bothered to spend ten bucks at lowes and get some HV wire. And I already did close the spark gaps a little because I had this guns first misfire which I blame on the spark gaps.

ipaintball:Yes I know that it is common belief that ABS tears but that is not how it happened when my spray and pray went boom a year ago.
And even if it tears there is still hot gasses blowing out of that tear, and it might hurt if they came into contact with you. I just dont trust DWV...

Spudfarm: DYI's barrel was solid core, like the chamber of this gun but unlike the potato barrel.

Edit: 1500 posts
yaaaayyy
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STHORNE
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Fri Jun 20, 2008 4:43 pm

nice build bob, and congrats on 1500
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bigbob12345
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Fri Jun 20, 2008 5:30 pm

Thanks

And Im really bored so I might just go make another video of it.
Any request on ammo/targets?
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Spuddin
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Fri Jun 20, 2008 5:37 pm

a jug of water hit with a gb would be in order...
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VH_man
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Fri Jun 20, 2008 5:49 pm

some kind of shotgun round, like marbles or Airgun BB's
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SpudFarm
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Fri Jun 20, 2008 6:02 pm

lead slugs at big old toy cars is fun.

ar at a big rock to get the nice bullet afterwards
"Made in France"
- A spud gun insurance.
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bigbob12345
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Fri Jun 20, 2008 7:05 pm

Spuddin: Consider it done

VH_man: Ill do that too

But spudfarm I currently am out of lead so that will have to wait.
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