Final Design
Our water bottle rocket design consists of low cost or recycled materials to ensure a cheap environmentally safe build for the rocket.
The rocket consists of a 2L plastic bottle as the main body as it is structurally strong and easy to attach parts to and can easily be acquired by anyone. The nose cone is 3D printed in 2 parts. The rocket top that connects the 2L plastic bottle and the nose cone. After 3D printing the nose cone you need to sand the nose cone down till it’s smooth and
The 3D printed nose cone was a relatively low cost and has a high enough impact strength, it is light weight so the rocket will travel further into the air with less thrust needed and it also is a strong material to protect the top of the rocket when it falls back to the ground
The fins are made from sheets of card stuck together and are attached to the main body of the water bottle using super glue. Initially we had 3D printed wings but we lost one during testing and had to make some replacements from cardboard for the launch.
Decision matrix for wing shape
0 = Poor 1 = Satisfactory 2 = Reasonable 3 = Very good 4 = Exellent
| Criteria | Elliptical wing | Rectangular wing | Swept wing |
| Lift coefficient | 2 | 3 | 2 |
| Drag reduction | 4 | 1 | 0 |
| Ease of manufacturing | 0 | 4 | 2 |
| Cost | 1 | 3 | 2 |
| Strength | 3 | 2 | 2 |
| Total | 10 | 13 | 8 |
Launcher
The nozzle is made using the valve of a bike wheel valve and a cork from a bottle. We made a hole in the recycled cork and glued the bike valve into it. Once attached into the rocket the valve can be used to pump air into the main body of the rocket without letting the water inside spill out.
When a high enough pressure is reached inside the body of the rocket the pin can be removed launching the rocket of the cork allowing the water to escape generating thrust.
After the rocket was built the rocket was filled with water up to a third of the bottle. The rocket was estimated to have reached heights of around 20 meters when tested.
The risks from testing this water rocket are that it has no parachute so the rocket will fall at a greater speed which could lead to injury if the rocket were to land on somebody. Another risk is that the rocket could fall over and fly off horizontally which increases the chance of it hitting someone.
CAD models & Engineering drawing
Water rocket assembly
Nose cone
