The Big Outdoors

Potato Cannons!

It’s simple, cheap, and fun to use. The potato cannon is a sure fire way to amaze your children and astound your guy friends. If you build it, they will… love you.

Todd note: It probably took us less than an hour to make.

Astounding the boys at church!

Ben and Sam with the Wilson Cannon

Notes from Fellow Potato Shooters

Todd,

Well, here it is…the Kelly Kannon. It successfully fired (into my garage) twice. It has a remote ignition…a barbecue igniter with wires. I use Right Guard as the fuel source…it produces quite the ‘pop’! The chamber is 3″ pvc (1 foot long) & the barrel is 1.5″ pvc (2.5 feet long). It has shot well into a tarp backstop using both apples and potatoes. The camo paint was the boys idea.

Hi Todd,
We used a grill igniter. I considered a Coleman lantern lighter too, but decided to use the grill one. I got the 2 wire kind from Wal-Mart and mounted it on the outside of the gun. To get the spark I inserted 2 long screws (1.5″) through the pipe at an angle into the ignition chamber such that the tips of the screws were 1/4″ to 1/8″ apart inside the chamber. Then attached the igniter wires to the screw heads on the outside of the chamber. Make sure you insulate the wires and screw heads well with electrical tape or you may get more of a charge out of the gun than you want.

If I were to build another one I would consider mounting the grill igniter directly into the chamber by drilling a large enough hole for the threaded part of the igniter to fit into the chamber and secure it with the nut that comes with the igniter. You will need make the igniter be like an auto sparkplug by adding a stiff wire from the side terminal on the igniter and run it down to igniter to near the tip of the igniter and have a small gap between the stiff wire and the tip of the igniter…like a spark plug gap. This will eliminate the need to mount the igniter on the gun, put the 2 screws into the chamber and run the wires on the outside of the gun.

We tried many different propellants and ended up liking Acquanet hair spray…. About 3 one second squirts and away you go. Also we raided old cucumbers from Debbie’s garden as ammo…that worked well and couldn’t beet the price..

~ Kent Brown

Hey Todd,
I got the same book (Backyard Ballistics). We built the air powered model potato cannon first. We have had a pile of fun so far. The thing with the air cannon is that you can stuff just about anything down it (as long as their is a seal made first). So far we have launched rocks, water, dead birds, and rotten eggs….Watch out below. So do you need any more encouragement? Get to it soon–its a riot!

Have fun,
Mike

My 11 yr old and I built one of these last Christmas. I gave him the book along with the supplies to build the thing all in a box as his “BIG” present. It took 3 days and 1 extra trip to the store to get it finished. He absolutely loved it! We shot dozens of spuds into the woods. His favorite target was a 50 gallon rain barrel about 100 yards away……………he’s a better shot than I am. Thanks for your note of encouragement. I’m going to drag the cannon out of the basement one night this weekend so we can see the 3 foot flame! Happy blasting!!

Marcus
Atlanta, GA

Todd,
We built and fired our potato cannon on Saturday….right on schedule. Thanks for encouraging me to put it on the calendar! The kids send their thanks too.

We made it according to specs but found that the ignitor flints were being used up vary fast. My son Bradley made a cannon of his own and we tried both to see which went farther. Well, he beat me by at least 100 feet! We then just used his for the rest of the day :) His shot sailed about 200 feet or so!

After using up all of our flint I got to thinking about alternate ways to ignite. I raided the barn and took off the push button ignition thingy from an old barbecue we had and that worked so much better. I had trouble with the original plan where the lantern sparker needed to fit into the end cap. I bought a few extra end caps after destroying the first one. Since I had some extras I used a fresh one for the barbecue push-button system. The way those work is by creating a spark across the gap between the two wires that the button connects to. I used electrical tape to make sure the gap was always there between the two wires (by taping them together). I then drilled a small (1/8″ I think) hole into the new end cap and stuck the wires through. Actually I stuck the wires through first and then taped them after that. Anyway the system worked much better with the push of the button causing the explosion. The lantern thing usually took 8-10 tries so this was much better.

Just wanted to pass along this alternate idea if you’re interested. I think we’re also going to build a modified version where the barrel is a lot longer. We may also use about 4′ of 1″ or 1.5″ PVC for the end part of the barrel. That way you can use smaller potatoes and the lighter weight may send them farther.

Also, I wouldn’t suggest this idea necessarily….but we had so much fun doing this for about 4 hours or so that I got a little cocky. I went back to the house and got my baseball glove and had the kids fire the potatoes while I stood in the field and tried to catch them. Once I caught one (after about 25 tries) we called it a day. I wouldn’t let them stop until I caught at least one :)

Enjoy…and God Bless!

Greg

Todd,
Just a coulpe of ideas to enhance the potato cannon experience. 
1. Make sure the ignition point (spark) is in the center of the combustion chamber.  You will get a more effecient burn and a more powerful explosion.  I’ve launched mine straight up and out of sight; after that we run for cover :-)
2. I use golf balls wrapped in duct tape.  They have a good weight to them, make a good seal, and they’re reuseable.  Add a wrap of florescent tape on the outside so you can see them easier.
~ Doug

Taken from the Backyard Ballistics book