In my free private time I am a member of the Antares Hybridrocket Club in Berlin for developing hybridrocketengines.
If you would like to know what are hybrid rockets, then you will find all necessary informations on the Antares website, specially here.
Above you can see me (left) with Daniel Koch (right) on the Long Night of Science in Berlin (13th May 2006) with the Antares 20kN hybrid rocket testbed