Hey Instructables,
There are many ways to reuse plastic bottles that are left laying around. Soem of these ideas include making water rockets. So rather than throwing your bottles away , follow these 7 simple steps to a make your own mini water rocket that can be blasted up to over a hundred feet. This design uses very few materials and took about an hour to make.
Materials:
-2 small plastic bottles
-Fin Templates (see link below)
-Hot glue gun and glue sticks
-Scissors or a utility knife
-Micro Servo (optional)
-Cardboard
-Packing tape or duct tape

Step 1: Start Your Rocket Body

The first step is to take 1 of your water bottles and cut the top off. Now you're left with two parts: a nose cone and your parachute chamber. One option to consider is instead of using two bottles, try using one for the body and cut up another for a nose cone so that you have a more compact and portable design. This eliminates a possibility for a parachute unless you make a really small but effective parachute.

Step 2: Assembling the Body

Next, take your last uncut bottle and glue it to the parachute chamber. You should have something like in image 2. If you feel your joint isn't strong enough, go ahead and strengthen it with packing tape.

Step 3: Parachute Holding System

Now, use a sharpie or something to trace the mouth of the bottle as shown in the first 2 images above. Then cut your circle out and glue it 2 cm away from the mouth of the bottle.

Step 4: Stabilizer Fins

Refer to the fin measurement and angle drawing above. It's 7.5cm tall and the 4 cm angles are 30°. The 8.3cm angle is 40°. Recreate the fin above using the same measurements and angles. Then take time to cut out 1 and trace 3 more onto some cardboard. I reccommend using an x-acto knife or a utility knif to cut these a precise as possible. You should have 3 fins once you finish.

Step 5: Attaching the Fins

Use a hot glue gun to attach the fins to the rocket body. Make sure when doing this to look from the top to see if the fins are pointing vertically or are straight. Do this until you have 3 fins.

Step 6: Conclusion, Launching and Safety

So now that you've finished your water rocket you can choose to leave it like this or give it an awesome paint job with spray paint. You could minwax or water proof the fins to make them more long lasting. Before launching, make sure to find a large, open field where it's not prohibited to launch. If your not sure about launching at the location, go ask someone. Of corse, laws will vary depending on your location and where you live. Launch your rocket far from people to prevent injuries and take a few steps away from the rocket before going for a launch. When launching without a Parachute, make sure to put the nose cone on really TIGHT or it may fly off during the launch. I do not take responsibility for any injuries that may occur and you launch at your own risk. Other than that thanks for reading my instructable and Happy Launching!