You can change design variables including the size, and shape of the rocket body, the fins, the nose cone. You can also select different materials for each component. RocketModeler 3 calculates the weight of the rocket and determines the drag coefficient from a table of experimental data. You can select from a variety of standard solid rocket engines. The program computes the center of gravity and pressure for your rocket and determines the stability. When you have a design that you like, you move to the pad, where you can launch your rocket and observe its flight trajectory. You can pause at any time to record data and then continue the flight through parachute deploy and recovery. RocketModeler 3 models stomp rockets, bottle rockets, and ballistic shells in addition to solid model rockets. It also supports both English and Metric units, and you can fly your rockets on the Earth, Moon, or Mars.