COME ON IN!!!!!!!!
THIS ROCKET WILL SOARRRRRRRRRRRRRR
Step 1: Gather and Prep Materials
Making a Water Bottle Rocket is fairly simple. This instruction will explain the basics physics of how it works, and how to make it.
The materials you will need
-10 Gallon Trash Bag
-2 Liter Water Bottle
-Hot Glue With Hot Glue Gun
-Duct tape (or masking tape)
-A Box Cutters Knife
Not much has to be done in prep. Take all labels off of the bottle. If the bottle has a huge lip, sand it down, but not too much. The lip has to be about an 8th of an inch.
Step 2: Cut Cardboard to Make Wings
The easiest way to make the cardboard wings, is to use the closing flaps. There will be 4 large flaps that can be used for the larger structure of the wings, and 4 small ones that can be used for the triangle base and circular string holder.
From trial and error, I learned that the most aero-dynamic shape is to make a triangular pyramid, which can be scene in the picture. It slices the air and makes it fly higher. There isn't too much physics to it, it just is less air resistant. The advantage to having a pyramid shaped wing is that it affects a larger area, and slices and pushes, instead of just slices, the air.
To make the wings, take a box flap and cut it so you have a rectangle thats 10 by 5. When you have the cardboard rectangle, cut it corner to opposite corner.
Now this is the tricky part. Your going to cut an isosceles triangle with two 5 inch sides and one 2 inches. Basically what your going to do to make this is draw a line that is two inches long. Then at the center point of the line (1 inch) make a 4.9 inch perpendicular line.
Glue these together to make a wing. You can make a back plate if thats easier for you. The dimensions of the back plate would be 2 inches at the base, with a height of 9.5 inches from the centerpoint
Repeat these steps 3-4 times. Depending on how many wings you want. I did this three.
I would suggest using hot glue for the wings.
Step 3: Make the Chambers
This is up to you, you can make one chamber, two chamber, three chamber, and if you're the Wu Tang Clan, 36 chamber rockets. I really don't advice going over 2 though, past 2 rockets, the center of gravity is too high up, and causes it to veer when launched. The first chamber should be left untouched, this will hold the water. For the second chamber, or any chamber there after, you just cut at the point in the picture provided. The chambers could have many uses. They can be used to hold the parachute and tennis ball, or they can be used to make the rocket more lengthy and streamline.
In my particular rocket, my stub of a rocket, I cut the second chamber for the ball to rest in, as to not take up any more space in the nozzle, and make it so the parachute won't deploy ( a common problem if you stuff them both in tight. Its hard to explain but easy to see. I cut it just under the lip i guess, in a hole a little bigger than the ball.
I duct taped my two chambers together. I found that gluing cause dents and bulges, not flushed edges, so i opted for good old fashioned friendly duct tape.
Step 4: Make the Parachute
A very good explanation can be found on this website- http://www.wikihow.com/Build-a-Plastic-Parachute
This is explained in small scale. I'd suggest that the length of your folded up triangle should be cust to 15 inches, resulting in a 2.5 foot diameter of the parachute. The larger the parachute, the slower it falls.
Place tape close to the edge 8 times, equal and even intervals separating each piece of tape. Feed your string through holes punched in the tape, and tie them snug (not together!). You only want 8 because you want a balance between stability, and something that won't get tangled. Something I did to stop it from getting tangled was made a cardboard circle (visible in pictures), about 3 inches in diameter, also 2ith 8 holes, to match up with the 8 holes on the parachute. You obviously feed the string through both the holes int the parachute, and that in the anti-tangling agent.
Now take the tennis ball and with a sharp knife, slice a slit right through it. Its hard to keep steady so be careful of your fingers. Pinch the tennis ball to open it up, and feed the string through, tieing it and taping it at the end.
PARACHUTE READY FO' DEPLOY!
Step 5: Make the Cone
This is very simple. You take a file folder, remove any reinforcement. After that take each corner and overlap them making a cone shape. When you have the desired size (you want it big enough to fit a bit over the wings if its single chamber, or the size of the bottle if its double chamber) tape it up. Cut the remaining so it has a flat base.
Step 6: ASSEMBLE!!!!!
Assembly is very basic. Glue the wings on, base in line with the lip of the nozzle, point torwards base of bottle. Wings need to be spaced evenly to fly straight, so if you have 3 wings, 120 degrees apart, 4 wings, 90 degrees apart. I'd advise you to use hot glue.
loosely stuff the parachute into the nose cone. When you stuff parachute, fold it into a triangle, and then roll. It's space effective and deploys easier. If you find your parachute won't deploy, lube it up with graphite powder or baby powder.
Now loosely fit the nose cone onto the rocket. Make sure it goes on straight!
And now, your ready to launch.
When launching, the best amount of water to use is about 2/3rds the bottle. Don't over pump, bottle may burst. The pressure in the rocket acts as fuel. The water acts as a projectile