The Manual for Real Boys

Today we finished the fourth and final project from a book called Backyard Ballistics. I have dubbed this book,"The Manual for Real Boys." Backyard Ballistics is a book with instructions on how to create fun, easy to do, ballistics.

We constructed the famous Potato Cannon for our first project, which is created completely from PVC pipe, PVC pipe cement, and duct tape. The cannon's barrel is a long piece of PVC pipe with a sharpened end. At the back is a piece that is shorter but has a wider diameter; this is the firing chamber. We wrapped duct tape around the firing chamber and its connection to the barrel, thus helping to prevent the pressure on the firing chamber from being too great, which might cause the Potato Cannon to explode. The back of the firing chamber can come off with a spark mechanism on the back. To fire it you need to simply insert a potato in the front, the sharpened part slicing off part of the potato, causing a decent seal. The potato is shoved down the barrel with a broom stick, not too far or it will fall into the firing chamber. The back is unscrewed, and hair spray is sprayed into the firing chamber. The firing chamber is screwed back in quickly and use the spark mechanism to make a spark within the firing chamber. The hairspray will light on fire and the expanding gas will shoot the potato out the barrel with incredible force! If you do it at night you can see flames come out of the barrel.

Hints: The cheaper the hairspray the more likely it is to work, and work well. Put a paper towel down the barrel before the potato so it will create a tighter seal. We have put in about three times the amount of hairspray they tell you is safe, but I wouldn't do that, because we are suicidally dangerous, and I will hold myself responsible for my mistakes, not yours. (Doing three times more hairspray is fun if you can avoid being blown to bits.)

Safety: Buy the book, it has lots of safety instructions and you will not regret it. Don't try to build one with my instructions, you will regret it. Don't point at people or animals, they will regret it.

Not Safety: Doesn't this make you wonder what would happen if you lit a match in a room full of people wearing cheap hairspray? Put more hairspray in the firing chamber!!!

The second project we did is the tennis ball mortar--easy to build, but can only be fired a few times. So I remember little of the tennis ball mortar, other than the fact that it shot a tennis ball extremely high, used a Pringle cans, and was a lot of fun.

The third project we built was a Pnewton's Petard, and like the potato cannon, fired potatoes. The main difference is that Pnewton's Petard used air power instead of combustion. The Petard also uses PVC pipe but looks like a T when complete. On one side of the T was an air valve, allowing you to pump air into the top part of the T. On the other side was a PSI meter, to keep track of air pressure. As you may have guessed, the bottom part of the T is the barrel, and you are correct, and at the start of the barrel is a ball valve, keeping pressure inside the top part of the T. Once we had completed the Petard we had to test for leaks. If there was a leak we would have to start all over. First we pressured it to 10 PSI as we held our breaths. The pressure stayed at 10 PSI. Then we pressured it to 30 PSI, and it held.

Hints: Use wadding, and you can also put a potato in, then stuff the leftovers in, causing a grape-shot like effect. And we have also pressured it to 45 PSI, but beware, the cannon might explode, causing injury.

Safety:Don't pressure it more than 30 PSI. Don't aim at people.

Not safety: Pressure it more than 30 PSI for a better launch. Doesn't this make you wonder what would happen if you built a giant Petard, put people inside, then pressurized it?

The fourth project that we just completed yesterday is called the flinger. Have you ever seen a water balloon launcher? If you have that is just what the flinger is, but homemade. If you have not seen a water balloon launcher, imagine a gigantic rubber band, with a pouch in the middle, and a strap on the back of the pouch. Two people hold onto the ends of the rubber band, and one person places an item in the pouch, grabs the strap, then walks backwards. The launcher releases the strap, flinging the object a great distance!

http://backyard-ballistics.com/

Here are videos of each item in action,(Excluding the tennis ball mortar.)