Complex sentence: Many of the teams choose to design their rockets on rocket simulation programs, such as Spacecad, or RockSim, these programs enable users to not only design rockets, but also calculate how well their rockets will perform in different weather conditions.
Split into simpler sentences: Many of the teams choose to design their rockets on rocket simulation programs, such as Spacecad, or RockSim. These programs enable users to not only design rockets, but also calculate how well their rockets will perform in different weather conditions.