*Sorry for the grainy pics.
Step 1: Materials
1. An average 2 Liter soda bottle
2. scotch tape
3. clear packing tape
4. an air pump
5. an average BIC pen, open on both ends (it'll have to fit in the pump, so one with a narrow end may be better.)
6. 2 straws (bendy or not, doesn't matter)
7. glue (hot glue preferred)
8. some poster boards (for the fins & nose)
9. A long, thin k'nex rod (recommended but optional)
10. a launcher, such as a cardboard box or a mediumish styrofoam cup
Step 2: Making the Plug
Take 2 straws and coat about an inch from the bottom with glue. Insert them together into the end of the pen valve that will go in the bottle and make sure they are glued. Let it dry.
This is to make no water go in the pen valve, and then into the pump.
Step 3: Fins
Of course, you can color them if you want...
Step 4: Waterproofing the Fins
Step 5: Taping Fins to Body
Anyways, just connect a piece of packing tape (as long as the side of the fin) from the fin to the bottle. Then, make it straight and tape the other side.
Repeat for the other fins.
Step 6: Making the Nose Cone
Step 7: Optional: K'nex Antenna
The K'nex antenna serves three purposes:
1-allows you to shift around the nose cone to get it to be straight
2-reduces impact if nose cone hits ground so the cone won't be destroyed
3-allows you to center the nose cone
Okay, to make it just tape the k'nex rod to the center of the rocket's bottom where you'll be attaching the cone. Be generous with the tape and make sure it's secure.
Then, cut a hole in the tip of the nose cone only big enough to let the k'nex rod squeeze through. Push the cone onto the k'nex rod and tape at the tip.
From there, you can adjust it to make it straight, and it shouldn't fall off.
Step 8: 3...2...1...
Place it on/in your launcher, which could be a box or something. I used a mediumish styrofoam cup that was open on both ends and put the pumper tube through one end and the bottle on the other end.
Insert the pen/plug into the pumper. Latch it closed and pump.
Step 9: Blastoff!
*Do not aim at people or living things