WHAT YOU WILL NEED:
8" X 8" corrugated cardboard
2-2 1/2 (outside diamater) flat washers
Turn a 2-liter bottle upside down, then tape the 2 washers flat to the bottom. Take another 2 liter bottle and cut as shown
Take the top of the bottle that you cut and tape to the bottom that has the weights taped to the bottom.
Cut the cardboard like the pattern below. Fold 6 bobby pins like the picture below. Take a knife and seperate the sides of the cardboard to the dotted line. Stick the pins in the cardboard so the 2 sides stay seperate.
Take the fins (you need three) and tape them to the bottom of the bottle. The bottom is where the nozzle is. Tape over the hole on top of the dome.
Call your 4H headquarters and ask for the rocket launcher.
TIP - Make sure that the fins are three inches from the bottom of the bottle.
Fill the rocket three fourths of the way up. Test what happens with different amounts of pressure and water. Never use more than 100 pounds of pressure.