Open Rocket Model Rocket Design Simulation Software
OpenRocket is a free source forge project with many features similar to commercial model rocket design and simulation programs. OpenRocket is a Java program that can run on many computer platforms that support the Sun Java libraies.
Winroc Model Rocket Simulation Software
Winroc is a free model rocket simulation software suite of programs that runs in the Windows environment. The Winroc model rocketry software suite will allow you to check the stability of your model rocket and then predict the altitude the model rocket will achieve!