Welcome to this instructable!

Whether it is for a school project or just for some summer fun, building and launching your own water rocket is a awesome but challenging experience . In this tutorial I will show you how to get started

and how to build your own, simple water rocket. :)

Plus

It will give you hours of great fun.

And impress your friends with them.

You probably have everything in your backyard that you need to make it.

If you don't it will not cost much to get them.

Step 1: Flight Videos

here is a flight video

Step 2: Introduction to Water Rocketry

A water rocket is basically just a pressure vessel, filled with air and water. When you launch the rocket, the water is forced out of the vessel by the air pressure, and it accelerates the rocket in the opposite direction(Newton's third law ). But besides a bottle, which is used as the pressure vessel, you’ll need to make a safe and secure launcher too. In this case, we’ll use garden hose connectors(They do not have to be the Gardena brand) for the launcher, because they can take a lot of pressure and easy to release.

Step 3: Materials for the Launch Pad

A Car tyre valve.

A 15mm Gardena hose pipe connector

A piece of 15mm garden hose (about 4 meters at least)

A clamp that fits over the hose-pipe

A length of rope (~6 meters)

A few cable-ties

Some scrap wood for the launch base.

A few nails.

Step 4: Materials for the Bottle

For the bottle

A 1" Gardena tap connector(the bottle cap must be able to fit in it!)

A 2 liter cool-drink bottle

A bottle cap

5 minute epoxy

Step 5: Tools

Tools

And a bicycle pump (preferably not a hand pump)

A craft-knife

A screwdriver(for the clamp)

A hammer

A drill

And a 16mm hole saw

And a 35mm hole saw

Step 6: Assembling the Launch Pad

If you want to have a good launcher, you’ll need a stand for your garden hose system. Just use four wooden planks like this. It’s very important that you secure the launcher to the ground so it doesn’t tip over from having a heavy rocket on it or when you pull the release rope.

The stand will need to have a 16mm hole for the garden hose, and a 35mm hole for the coupling. Now you can push the hose through the small hole, and glue the coupling into the hole using a hot glue gun.

Step 7: The Air Pump Side

Attach a car tire valve to the other end of the hose. You may have to cut off some of the rubber at the back of the valve,

which will then allow you to push it into the hose. You MUST then secure it with a clamp tightly.

Step 8: The Nozzle

Now it’s time to start with the construction of the nozzle,

which is the adapter between the rocket and the launch pad.

Just drill a hole into a bottle cap, and increase the diameter to ~14mm. Remove the seal from the 1“ tap nut adapter,

and then scratch the bottle cap so the epoxy can stick well.

Then glue the bottle cap into it using epoxy resin. Let the nozzle cure for at least 48 hours.

Step 9: Rocket and Fins

But what about the rocket itself?

You will need a stable and thick-walled plastic bottle, to make up the body of the rocket. You just have to add some fins, made of thin, stiff and lightweight wooden or plastic materials. In this case, I am using "foamboard". Feel free to try different fin shapes, but if you want you can download our fin templates from Here .

Use a craft-knife to cut out the fins, you will need 4 fins.

Take a fin then glue it to your bottle with hot-glue

Then take another fin and glue it on the opposite side of the bottle.

Then glue a fin in between each of the fins that are already on.

So there are four fins evenly spaced around the bottle

But be careful: Don’t let the glue get to full temp,cause it will melt the plastic bottle.

i also recommend reinforcing the fins with duct tape.

Step 10: Final Steps

After the nozzle has cured for 48 hours, you can screw it onto your rocket.

The only missing part is the release mechanism.

Just attach two strong strings to the coupling with a cable tie

then have the strings go thru your launch base

so when you pull the string to the side it pulls down the coupling’s collar and launches the rocket.

Step 11: Launch

Now your rocket is ready to launch. Choose a launch site, which is far away from houses, streets, trees and power lines. Secure your launcher to the ground, and attach your air pump to the hose system. Fill the rocket ~1/3 full of water, and put the rocket onto your launch pad. You should raise a part of the hose above the water line in the rocket to stop water flowing back into the pump.

All you have to do now is build up the pressure with your air pump. Please be careful, and always wear safety goggles. Don’t try to use too much pressure, 5bar (70 psi) is enough for your first try. You can use more pressure later, but always be aware that the bottle can explode.

As soon as you have enough pressure, just pull the string and the rocket will launch.

I wish you much success in building your own water rocket. If you have any questions, please feel free to ask in the comments section below. :)