This instructable is based on my knowledge of water rockets, that I have learn in the past few years.
I am not responsible for any damage you infict on your self or others from launching or building water rockets
Have fun building and flying!
Step 1: Lets get Started
If you took a standard two litre fizzy soft drink bottle and pressurised it to120 psi the rocket would reach about 100 or so feet.
But then if you took 2, two litres bottles and pressurised it to 120 psi again the rocket would go about 150 feet or so because the rocket has more air in it therefore creating more thrust. The rocket will only go 50 feet more because of the added mass. You can stop this by making a two stage rocket. A two stage rocket will work better because it would not have to carry the full payload on all of its flight.
Step 2: How to build a fins and nose cones
This step is to get to grips on what a rocket needs.
Step 1: nose cone
cut the top and bottom off a 1.25 litre bottle. Then cut the neck off the top.
Step 3: Step 2: Nose cone
Cut a ping pong ball in half with a craft knife,
Then glue half of the ping pong ball into the top of the 1.25 litre bottle 'top'.
Use a Plastic adhesive glue, Or if apperance doesn't matter you could just tape it on!
Step 4: Step 3: Nosecone
Adding wieght to the nose cone may help, It will move the centre of gravity higher, thus being more stable.
Step 5: Fins
Print off the fin template from the link below... Or design your own..
Then glue the fin template on to cardboard, then cut it out or use it as a template for corregated plastic.
Step 6: Attach the fins
1. Glueing them on
2. Taping them on
To glue correx fins to the rocket use PL premuim or a plastic glue.
To glue Cardboard fins on use PL premuim or gorrilla glue.
Step 7: Now for the professional water rockets
This stage of the instructable will show you how to make a big one stager and how to couple or splice bottles together.
step 1 : coupling and splicing
How to couple bottles
first drill a hole about 7-8mm in width in the bottom of one of your bottles.
Next screw the male end of a plumbing coupling which is about 8mm in width into the bottom of the bottle, then seal it with a sealent glue. Next drill an 8mm hole in the other bottle cap and then insert the male end in to it. Whist the bottle cap is off the bottle, screw the female end into the other side of the bottle cap (side facing the inside) If you want you can seal it with glue as well.
Step 8: Splicing
To join two bottles together like in the picture to create an air tight seal you need three bottles
first cut the bottom ends off two of the same sized bottlles
Then cut both ends of the same sized third bottle and place that in the two exposed ends of the bottle
Next glue the third bottle in the 2 exposed ends.
Step 9: Launchers
The launcher lets you vary the nozzle size so you can get better performance from your rocket.
The next few steps will show you how to make it.
PDF from NASA below
Step 10: Launcher parts
1 1/2 inch wood (any type)
2 10mm bolts
1 10mm metal drillbit
1 10mm wood drillbit
6 10mm nuts and washers
1 presta bike valve (you can get this from an old inner tube)
1 rubber bung
1 bike pump
2 tent pegs
4 L (shaped) brackets
Step 11: How to make the launcher and nozzles.
The launcher can hold any type of pressure depending on the rubber bung.
If you have a different nozzle size then you can adjust the nuts on the bolts so the pins can line up with the hole in the 90 degree mending plate and the neck of the bottle.
Step 12: Two Stage rockets
I have tried to make the stager compact. The stager can link to a servo or a pressure switch.
The instructions for it are on the next few steps.
Step 13: Stager
1 22mm pipe any lenth over 15cm
1 plywood or you can use plastic. (to hold the bottle in place)
1 inline non return valve..... One from a ballon pump will do
1 a 1st stage of a bottle rocket and a 2nd
1. insert 2cm of the 22mm pipe in to the 1st stage. ( pic1)
2. use epoxy or pvc sement to seal it. (pic 1)
3. insert a non return valve into the pipe and glue it.
3.work out the dimensions of how long and wide the plywood or plastic needs to be, to hold the bottle in place. Then cut it out using image 2 to help you. The hinge is mounted on the pipe clamp.
4.when you slide the bottle on (use vaseline to seal it) make sure the pipe clamp is right next to the neck on the first stage. This will have your hinge on, next clip your hinge onto the bottle neck so it is tight and won't fall off.
Step 14: Drop away boosters!
These drop away boosters are differernt to Air Commands.
For the drop away boosters you will have to make three of the launchers.
Instructions(drop away boosters)
1.measure your drop away booster bottles against your main rocket. Make a mark (dot or line) where the top of the booster meets on your rocket.
2.use pic 1 to help you, where you marked a dot on the booster glue the advanced fins together and stick the bottom of the fins on the marked dot with duck tape or glue. The Advanced fin template is on step 15.
3. test the rocket!
Step 15: Advanced fins
for fins print off the template below
Step 16: Payloads and parachutes
The parachute system used by me 'OscarThompson' is a simple gravitational deployment.
The nose cone is fitted on the rocket loosely and when the rocket reaches its maximum altitude the rocket will fall back to earth nose first and as the nose has a weight in it, it falls off deploying the parachute inside.
Step 17: Step 1,2,3,4 of parachutes
Find a payload bay for your rocket. any size to fit a parachute
Build a nose code like as shown in steps 2 and 3. Your nose cone either needs to fit loosely on top of the payload bay or loosely in it.
cut a hole in the payload bay and the nose cone so a string can fit though it and be knotted.
tie the parachute string to the string you have tied to the nose cone and the payload bay.
Step 18: Payloads steps 1,2,3
payloads are used to carry equipment such as altitude meters, accellerometers or even a slug (wierd, but the g-forces can kill it!)
cut the bottom off any size bottle.
cut two disks the same width as the bottle out of corregated plastic
cut a strip out of plastic the same width as the bottle but a little bit smaller in length than the bottle
Glue them together and when dry put your payload into the payload section of the rocket.