The nose cone of the rocket has a shape that causes the air to flow smoothly around the rocket. It could be conical in shape, but at subsonic speeds a rounded shape gives lower aerodynamic drag. The nose cone is typically made from plastic, balsa wood, hardwood, fiberglass, or styrofoam. It can be either hollow or solid.
Shock Cord Mount
The shock cord must be attached to the body of the rocket. There are many ways to do this, but the most common used in model rockets is a folded-paper mount glued to the inside of the body tube. It is also common to connect the shock cord (or a separate anchor line) to the front of the motor mount in larger-diameter rockets.
The shock cord holds the parts of the rocket together after they separate at ejection. The shock cord may be made of an elastic material to help absorb the shock of the separating parts coming to a halt at the ends of the cord, or it could be made from a non-elastic line (in which case it is normally longer). Typical materials for shock cards are sewing elastic, rubber, nylon, and Kevlar.
All model rockets require a recovery system to slow their descent and return them safely to the ground. The most common type of recovery system is the parachute. The parachute may be made from thin plastic or cloth. The parachute is expelled from the body tube by the ejection charge of the rocket motor after a delay to allow the rocket to reach apogee and be traveling at a relatively slow speed. Other recovery systems include streamer, featherweight, glide, helicopter, body drag, and tumble.
The shroud lines connect the parachute canopy to the rest of the rocket. The shroud lines on most model rocket parachutes are made of strong thread, such as carpet thread, but they may also be made of other material. The number of shroud lines varies, but is typically 6 or 8 lines on a model rocket parachute. More shroud lines can cause a simple flat parachute (a “parasheet”) to form into a more nearly spherical shape, and therefore be more efficient.
The body tube (or tubes) are the airframe of the model rocket. Body tubes are typically made from paper, fiberglass, or plastic, with the spiral-wound paper tube being the most common. The rocket may have multiple body sections connected with transition sections (if the tubes are different diameters) or nose blocks or couplers (if the tubes are the same diameter). The body tube usually contains an engine mount to hold the motor, and space for the recovery system.
When a model rocket first begins to lift off, it is traveling too slowly for the fins to provide aerodynamic guidance, so the rocket must be guided for the first few feet by a launch rod or rail. The launch lug is what allows the model rocket to slide along the rod. On a model rocket, the launch lug is typically a small diameter tube. Larger rockets may use rail buttons on the side of the rocket to allow it to slide along a much stiffer launch rail for initial guidance.
The fins of the rocket provide aerodynamic stability in flight so that the rocket will fly straight (in the same way that the feathers of an arrow help it fly straight). The fins are typically made from plastic, balsa wood, plywood, cardboard, or fiberglass. A rocket three or four fins, but may have more. Some rockets don’t have any fins and may rely upon a cone or other surfaces to stabilize the model in flight. On larger rockets, the fins may be mounted through slots in the body tube for extra strength.
The engine block, or thrust ring, keeps the rocket motor from moving forward into the rocket body during the thrusting phase of the flight. Engine blocks are typically thick paper rings that are glued into the motor mount tube. If the rocket body has a larger diameter than the motor, the motor mount tube that holds the rocket motor will be centered within the body tube using cardboard or plywood centering rings.