First time potato launcher!

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.
Kennymester
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Sun Aug 17, 2008 10:53 pm

This is my first time constructing a potato cannon. Originally I was having a lot of trouble getting the right fuel mixture, but after adding a fan I'm having 100% success. The measurements of the cannon are 24in of 4in pipe for the combustion chamber and 48in of 2in pipe for the barrel. I inject propane through an 8in meter setup and use a grill lighter to ignite the mixture. The longest shot I've gotten so far was around 240 yards at a 45 degree angle. This week as well I will begin construction on a movable turret for the gun. The pictures below show my gun, the back end with fan, and a piece of plywood I hit at 100 feet. Comments are welcome.

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taytayswims
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Sun Aug 17, 2008 11:10 pm

such a clean gun and the damage is quite impressive for 100 feet
brother361
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Sun Aug 17, 2008 11:19 pm

im pretty sure thats a dwv tee i think you would be fine but its alwasy good to be on the safe side
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Stifler69
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Sun Aug 17, 2008 11:27 pm

Wow man what an awesome potato gun !!!
You are so not a first time gunner from what I've seen here haha.
But yeah really nice gun, you should get some action of it on film.
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starman
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Sun Aug 17, 2008 11:34 pm

A little bit of a Rube Goldberg setup you have there. However, you've got it working consistantly and that counts for a lot. The propane canister looks funny hanging out there in seeming mid space.

Do something constructive with your battery holder and replace that duct tape with a hose clamp or even tie wraps.

Congrats on building a successful advanced combustion!
Kennymester
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Sun Aug 17, 2008 11:47 pm

Stifler69 wrote:Wow man what an awesome potato gun !!!
You are so not a first time gunner from what I've seen here haha.
But yeah really nice gun, you should get some action of it on film.
No I really am I first time gunner. I just did a a lot of research and calculations before I did it. =)

I have to make it a priority to tighten up the design a bit. It's not too much of a problem to make some extra trips to the hardware store considering I work there. Lol

I'll see if I can get a video of it tomorrow.
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Stifler69
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Sun Aug 17, 2008 11:54 pm

haha nice well great job buddy
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mister pointy
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Mon Aug 18, 2008 8:39 am

Great job on a first gun! Now that you have the gun working, you should try cleaning it up a bit. Tuck some of those wires away and replace your tape with clamps or zip ties.

Then, once you get your turret done, you'll have a great piece to call your first cannon.
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starman
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Mon Aug 18, 2008 10:30 am

Also, what was your reasoning for the fan attachment/choke point design in the back?
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psycix
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Mon Aug 18, 2008 3:58 pm

Looks good for a first gun.

But it has some weird aspects, summed up as:
-Propane tank floating around somewhere. (you could possibly position that between the meter and the chamber)
-Meter pipe being very far away from your chamber. (instead of using a tee, you can just tap an hole and screw it directly in there)
-Excessive amount of fittings, weird reduction (and then scaling up again!) in chamber diameter near the back.
-Pink thingy on the barrel. (Not that it is wrong, but it looks weird)
All this is not wrong, its still a great gun. Its just, well, unique in its shape.
Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

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Kennymester
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Mon Aug 18, 2008 6:27 pm

Well I can answer some of your questions. Well the back part of it was originally made so a threaded ball valve could be placed on the back. Long story short it didn't work that well. I already had threads there I had to use so I just made it interchangeable with other things. Also under the circumstances where the fan might break I can just make a new holder. I was also thinking in terms of a rocket when picking out the fittings so I though that if it was kind of like a nozzle in going from big to small to big it might give me better compression. I did fix the propane tank and turned it 180 degrees. As far as the battery holder and stuff I want it confined to the back piece so I think I'm going to keep it like it is. I might paint it in the future too, but I like the homemade look of it. I also ordered some parts for my next one as well which is going to be a golf ball gun.
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Radiation
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Tue Aug 19, 2008 12:14 pm

I've never seen any problem with DWV fittings, but it seems to be a pretty ingrained myth on this site that they are not preferable. I personally have used them with great success. extraordinarily nice for a first cannon! Congrats!
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psycix
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Wed Aug 20, 2008 7:59 am

Okay, so now we know the story behind it all.
Good that you turned the propane tank around. I suppose it looks better now.
Any pic of that?
Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

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