Step 1: Materials
1. A Pvc pipe at least twice the lenght of the bottle.
2. A waterbottle that fits in the pipe.
3. A plastic tube
4. Corke thing
5. Baking soda
7. Cone (not pictured, too lazy)
8. Duct tape.
(I made this before I knew about instructables so there aren't many pictures)
Step 2: Cut the Pipe
I found the right size pipe in my garage, it can be as long as you like for improved accuracy, but at least twice the length of the water bottle.
Step 3: Insert Cone
Insert a plastic cone (or anything else to block one end) and cover the same end with duct tape. If you leave holes in the tape, it will have the backfire effect of a bazooka.
Step 4: Enjoy!
This can be used with any bakingsoda vinegar rocket you want. look up how to make the rocket, or keep following this instructable.
*Warning, you might get covered in a very nasty smelling gunk, could get in eye*
Step 5: Building the Rocket
First, put the cork into the small tube, I got mine off of a rocket kit. Fill the tube about three fourths of the way with baking soda. Fill the water bottle with vinegar untill you can tip it completely horizontal without spilling. When it is horizontal, carefully insert the bakingsoda filled tube without spilling the soda into the vineger. Then flip the bottle cork side down and tighten the cork.
Step 6: Putting In
Slide the bottle carefully into the launcher. When time to launch, tip the launcher down and back up in one movement, dumping the bakingsoda into the vinegar and bring it back up, seen in vid.
Step 7: Make Minis!
You can cut the bakingsoda tube to fit in mini bottles to make a small RPG that goes farther.
The vids below are my friends and I messing with the rockets (the music was playing on the radio behind us, didn't know the camera caught it)