STAGE 1: LAY THE GROUNDWORK
Welcome to Stage 1. Here, you will learn the vocabulary of flight. Before glue touches cardboard, you must understand the invisible forces acting upon a vehicle in motion.
THE FORCES OF FLIGHT
Four primary aerodynamic forces govern a rocket: Weight, Thrust, Aerodynamic Lift, and Drag. In vertical rocket flight, thrust must aggressively overcome weight and drag. Because model rockets are unguided, stability is achieved entirely through aerodynamic design.
To ensure a stable flight path, you must calculate two critical points on your airframe:
- Center of Gravity (CG): The exact balance point of the rocket with the engine installed.
- Center of Pressure (CP): The point where all aerodynamic pressure forces act upon the rocket (heavily influenced by the fins).
The Golden Rule of Stability: The CG must be forward (closer to the nose cone) of the CP by at least one full body tube diameter. If the CP moves ahead of the CG, the vehicle will tumble erratically upon launch.
ANATOMY OF A ROCKET
NOSE CONE
The aerodynamic leading edge. Its shape (ogive, conical, or elliptical) dictates drag coefficients at different speeds. It must fit snugly but slide off easily during the ejection charge.
BODY TUBE
The primary structural fuselage, typically constructed from spiral-wound kraft paper or fiberglass. It houses the recovery system and acts as the airframe.
FIN UNIT
The stabilizers. Positioned at the aft (rear) to pull the Center of Pressure downward. Made of balsa wood, plywood, or molded plastic.
ENGINE MOUNT
A smaller tube inside the main body tube that houses the solid propellant motor, held in place by centering rings and an engine block.
PROCEED TO NEXT STAGE
You now possess the foundational theory. It is time to transition from understanding the physics to applying them on the workbench.
BEGIN STAGE 2