We are the Bristol branch of UKSEDS (UK Students for the Exploration and Development of Space). Here are some of our projects.
The UBSEDS20 balloon was built from 50 micron thick PA-EVOH-PE multilayer film and was 1.9 meters in diameter. This is 0.4m more than the usual 1.5m diameter. The larger size meant the longest axis of the balloon and payload combined was more than 2 meters, and so a NOTAM was required and obtained for the launch.
Like UBSEDS14, the UBSEDS15 balloon was built from 50 micron thick PA-EVOH-PE multilayer film and was 1.5 meters in diameter. The payload weight was 20 grams. We used slightly more helium than for UBSEDS14; combined with about 3 grams of deadweight (including the fill inlet) this resulted in 17.2 grams of free lift. This initial float altitude was 11.4km (37,000 ft).
The main project of 2013/2014 was to launch a high-altitude balloon into the stratosphere, where it could take photos and video, and to subsequently recover it. The balloon was successfully launched on the 15th June from an airfield near Tewksebury, Cheltenham, and landed near Glastonbury. It reached an altitude of 32 km, and spent about 3 hours in the air.