2 - 2-Liter soda bottles
3 - cardboard wings
1 - tennis ball
3 - garbage bags
6 - 3-foot-long pieces of string
2 - balloons, blown up to the point where they can safely fit inside the open bottle.
1 - liter water.
Step 1: One.
Remove all covering from your bottles, and cut the bottom segment off of one of them.
Step 2: Two.
cut the following shape wings out of cardboard.
they're aerodynamic. and they look funky.
Step 3: Three.
flatten out three garbage bags by cutting along their seam, then tape them all together, side-by-side. the result should look like a rectangle. on the two shorter sides, hole-punch and reinforce three holes each - two for the corners, and one in the center of the side. put a piece of string, about three feet long, through each hole, and knot. take all the strings and, with strong tape, secure them to the tennis ball.
Step 4: Four.
take a blown up balloon, and put it in the bottle. put the garbage bag parachute with the tennis ball in the bottle, and put another balloon in with it.
Step 5: Five.
Go outside and launch your rocket with a pump and a stopper.
Hope the air pressure makes your balloons make the parachute deploy.
Hope really hard.