Simple Combustion Cannon

Hal0 x · Posted: 08/24/2005 0:24 AM Post subject:

Like the Title Says Simple Combustion Cannon...Good first Timer

Parts

# 2 feet of 2 inch dia. PVC or ABS pressure rated pipe
# 1 foot of 3 inch dia. PVc or ABS pressure rated pipe
# screw off end cap for 3 inch pipe (note: clean out plug may be used)
# slip to threaded 3 inch fitting
# 3 to 2 in reducer
# PVC or ABS cement (note: do NOT mix PVC pipes with ABS pipes or fitting, only use PVC cement on PVC and ABS on ABS)
# BBQ ignitor
# 2 drywall screws
# hair spray
# plenty of spuds

Assembly

1. Cut pipes to correct length's with a hacksaw

2. Glue the barrel and the chamber to the reducer as shown in the diagram. (if PVC is used don't forget to apply primer first.

3. Close off the end of the chamber with the fitting and screw-on end cap or the drain plug cap.

4. Screw the drywall screws through the sides the combustion chamber so there is about a 1/4 to 3/8 inch gap

5. Connect the sparker to the drywall screw and make sure it fires properly, if no spark fires move screws closer and re-test.

6. Bevel the end of the barrel so that the potato will be cut to size when it is loaded. Beveling can be done with a Dremel or if one is not available a file can be used.

7. Let cement dry for about an hour (this time can be used to go buy some spuds!!)

Firing Tips

Caution: Only fire in open spaces far away from human life

1. Load the gun by cutting a large enough potato in half and then cutting it to the right size by pushing it into the barrel of the gun and letting the gun cut the potato's shape. If the potato is too small the potato will not go very far, for most of the gas will escape. Providing a good seal is the key to distance spud launching.

2. Get a stick that can be used to muzzle load the potato. Measure out how far on the stick the potato has to be pushed down to be right before the combustion chamber and push it down to that level.

3. Unscrew the back and fill with propellant. I like using pure propane from a blowtorch, but if one isn't available then hair spray can be used. This is the trickiest part of all. The correct mixture of gas to air has to be present for the gun to fire. Experimenting is the best way. One thing that is important to remember is that the gas needs oxygen to combustion therefore after each time it is fired air must be allowed into the chamber.

4. Good Luck.

Thats it. Have Fun