Our guidance system involves using a gas cylinder attached to electronic valves controlled by a raspberry pi in order to precisely control the rotation of the rocket, and keep it pointed straight up.
The pressure of the CO2 is decreased to levels the electronic valves can handle by allowing it to expand into the expansion chamber, as shown by the changing colour of arrows below
An animated diagram is shown below:
A higher quality diagram is below:
27/03/17: We are not going to use a CO2 cylinder for air pressure, since we can use a bike pump instead, and it will be cheaper and lighter. We will not use a raspberry pi for the controlling electronics, since it is not suited for controlling valves. The chamber will also be at a lower pressure, since high pressures increase the likelihood of it rupturing.