Choosing the right recovery system is going to be important for the UKROC challenge. You'll need to simulate your design to fine tune it using a rocket simulation software. We've put a collection of suitable parachutes here, but we do have further options under the main scratch building tab if required. As you will need to fly your rocket multiple times we advise picking Nylon parachutes rather than plastic ones. These will last for many more launches and be more forgiving.