I have made many different rocket launchers but most didn't hold air pressure for a long period of time. This rocket design can hold high air pressure for a very long time.The way it works is by building up air pressure in the tank and when ready you release the pressure into bottle and releasing it to launch the rocket.
You will need:
Two 20 ounce Pepsi bottles
6" of 1/2" pvc
3" of 2" pvc
Some thick gauge wire ( I used the wire from a campaign sign frame )
at least a 3" square of a 2x4
One gallon propane tank
Two threaded 1/2" connectors
1/2" three way "T"
Pressure valve with 1/4" threads (optional)
1/2" ball valve
three way "T" with two 1/2" and one 3/4"
Valve Stem with threads
at least 2" of 2x4
Step 1: making the rocket
You will need two Bottles, one to hold the tank and the other to make a nose cone. There are two ways of making the nose. One is a sharp, pointy tip that is made using the flat middle part of the bottle.
Step 1: cutting the bottle
1. Cut the bottle at the the top part were the cap goes. ( Cut the hardened part with a hack saw.
2. Were the bottles goes smooth cut about and inch below. Look at the picture for a better understanding
Step 2: Balancing
1. Use a quarter in the big hole in the front.
2. Put two pennies on the bottle where the cap you cut off covers
4. Take five pennies and place them evenly
5. Glue all them on (epoxy would also work)
Step 3: Attaching the tip
1. Attach the tip with ether hot glue or epoxy.