Computer drawing of the forces on a model rocket.

Flying model rockets is a relatively inexpensive way for students to learn the basics of aerodynamic forces and the response of vehicles to external forces. Like an aircraft, a model rocket is subjected to the forces of weight, thrust, drag, and lift. There are, however, some important differences in the actions of these forces on a model rocket as opposed to a powered aircraft or a glider:

  1. On an airplane, most of the aerodynamic forces are generated by the wings and the tail surfaces. For a model rocket, the aerodynamic forces are generated by both the body and the fins. For both aircraft and model rocket, the aerodynamic forces act through the center of pressure (the yellow dot with the black center on the figure).
  2. On an airplane, the lift force (the aerodynamic force perpendicular to the flight direction) is used to overcome the weight of the aircraft. On the model rocket, thrust is used in opposition to weight, and lift is used to stabilize and control the direction of flight. As the rocket is buffeted by the wind, it naturally turns back to stable flight if the center of pressure is located below the center of gravity (the plain yellow dot on the figure).
  3. While most aircraft have a high lift to drag ratio, the drag of a model rocket is usually much higher than the lift.
  4. While the magnitude and direction of the forces remain fairly constant for an aircraft, the magnitude and direction of the forces acting on a model rocket change dramatically during a typical flight.

Separate slides show the forces acting on a model rocket during liftoff, powered flight, the coasting flight going upward and downward, and the final parachute recovery.

A model rocket rotates in flight about the center of gravity (the average location of the weight of the vehicle), just like any other flying object. It is easier to determine the center of gravity for a model rocket than for an aircraft. There are fewer components on a model rocket, and the geometry is much simpler than for an aircraft.

NOTE: Modern full scale rockets do not usually rely on aerodynamics for stability. Full scale rockets can pivot their exhaust nozzles to provide stability and control. That's why you don't see fins on a Delta, Titan, or Atlas booster.

Button to Display Slide

Guided Tours

Button to Display Aerodynamics Index Button to Display Propulsion Index Button to Display Model Rocket Index Button to Display Kite Index

Back to top

Go to...

Beginner's Guide Home Page

byTom Benson
Please send suggestions/corrections to: