Model rockets are a nerdy hobby that can combine aerodynamics, electronics, radio technology, computer simulation, photography, art, composite materials and freezing your ass off in winter. Mixing your own propellants is not required nowadays, so it is also relatively safe. I have built many small models that fly on A...D motors, and have contributed to SATS's and Pollux's joint Haisunäätä projects, which used J and L class hybrid engines. I have been responsible for experimental avionics, control electronics, onboard cameras, data logging and radio beacons.

Here's some stuff and more photos:

Antti J. Niskanen <uuki@iki.fi>