RockSim simulation software lets you design and build your own customized rockets and see how high they fly! RockSim is a computer program that allows you to design any size rocket, and then simulate its flight to see how high, and how fast it will fly. You can also use it to find the best rocket motor combinations for your existing kits, and to teach yourself and others about the physics of rocket flight. More modelers, teachers, and engineers use RockSim than all the other rocketry programs combined! RockSim is available for both Windows and Macintosh OS X computers.