By now you’ll have seen that there are a lot of rocket materials available, let’s start by looking at rocket tubes.
The most common tubes for model rocketry are cardboard tubes, these are cheap and light, which makes them very attractive for building your first rocket, they also come in a range of standard sizes known as body tubes (BT) and coupling tubes (CT).
For each BT there is a corresponding CT that is intended to go inside body tubes so that two lengths of BT can be coupled together. Some body tubes have the correct diameter for motors, for example fit BT20 fits 18mm motors, BT50 fits 24mm motors.
To insert a narrow tube inside a wider one you need to use a centring ring (CR). These mount one tube precisely inside another, and are designated to show which BT diameters they are intended to centre. A CR50/70 is intended to fit a BT50 (smaller diameter) into a BT70 tube (larger diameter).
Centring rings are commonly made of cardboard or plywood. Plywood rings are much stronger and can take the thrust of several motors, so we’d recommend using these on UKROC rockets. Other types of tube that could be used include the following:
- Phenolic tubes
– Heavier than cardboard
– Great for areas of the rocket where strength is important
– Two good manufacturers are PML and Black Cat
- Blue Tube
– Originally made to be used for tank ammunition
– Heavier than phenolic tubes but extremely strong