Coke Can Combustion Cannon
This is a very simple easy to make combustion cannon. I'm not saying it's great or the best, but it can be pretty nice if made right. Again, simplicity is what we're going for here. Right, so what you need is just a bunch of empty coke cans or beans cans. Those strong walled protein shake cans are the best that I could find. I think I used 5 or 6. And some tape to tape it all up.
Now to make this, you'll need to cut off the top of all the cans first. Then cut off half the bottom of all the cans but one. The can with bottom intact will be your last can. It will be used for inserting fuel and will be your ignition spot. Take this can and make a small hole on the side, close to the bottom. Now all the cans are ready.
Next thing to do is put them all together. The trick here is in the arrangement. The cans will be stacked on top of each other in a certain fashion. The can with the bottom intact is your base can. That's goes at the bottom. Duh. Next, take a can with half a bottom and place it on top. So far, so good. You'll want to tape these together where they meet to hold them in place.
Now take another can with a half open bottom and place it on top. The opening should be on the opposite side of the opening of the can below it. Basically, if the first can's (bottom) opening in on the left, the next can's opening should be on the right. Now tape it up. Keep adding the cans in the same way and you'll end up with alternation openings in the bottom. Left side open, right side closed and vice-versa.
Basically this will force the gas to move around barriers and it will build up pressure. The pressure then pushes the projectile out. Simple enough right?
Now that the cannon is all prepared, just tape up the whole thing to make it secure. You don't want it moving around and gas escaping. Ok, the cannon is ready for firing.
Squeeze a few drops of lighter fluid into the small opening you made in the bottom can. You don't need a lot, just a bit to get a good combustible air mixture. Now put your hands over the openings and shake it up to get the vapour to mix all through. Insert your projectile at the top and you're ready to go.
When you're ready to fire, remove your finger from covering the small hole and bring a flame to it. The gas will combust and force the projectile out. There is also quite a loud boom accompanying the combustion, so try to keep it away from right beside your ear.
Now the cannon is full of CO2 so before you fire again, you'll need to air it out and replace the missing oxygen. And that's all there is to it.
Now of course there are better combustion cannons to make and they aren't too hard to construct. I'm just documenting what I've done and how I've done it. This was how my chemistry teacher introduced hydrocarbon combustion to us. Firing styrofoam eggs in the classroom. We were told to aim at the birds on the posters. Ah, good times. My brother had the same chemistry teacher and had the same demonstration, and he's the one who actually put the cannon together. It's quite an interesting way to learn chemistry.
