You wrap tape or a cardboard ring around the engine mount until it fits tightly in the fuselage tube.
In a model rocket that uses engines, there is an engine mount. The engine mount is located inside the body tube in the bottom where the engine goes. It usually consists of a small tube, two rings that connect it to the body tube, and a metal bar to hold the engine in the tube. Its job is to house the engine and hold it in place for a flight. glad to help, Uujjee
A block ring holds the engine firmly in the rocket tube. If not for this, the engine would go up the tube and the rocket would go on fire.
It's a small metal hook the length of the motor tube, fitted into the motor mount. This clips over the nozzle end to hold the engine in place when retro firing happens at the end of flight. If you didn't have this hook, the motor would blast out of the back of the rocket when it 'retroed'
The body tube of a rocket is there for friction. As the rocket comes back down the body tube along with the fins are there to slow it down. Also the longer the body tube the faster your rocket will go. The body tube gives it a narrow edge.
A rocket body tube is the center of a rocket; also the piece that holds the rocket together.
They usually have a shaped clay nozzle formed into the end of the engine tube. This differs slightly for the intended duration of the engine.
Propellant Controls - usually tail fins Gyro - keeps rocket on course Payload
With a good design and light tube, it will go 4-5,000 feet.
If you have a standard kit, the motor goes in the tube at the bottom so that the end of the motor with a clay nozzle sticks out. Place an igniter in the motor and (if you are using Estes or Quest motors) put the plug ontop of the igniter and push it in. Turn the rocket upright and put it on the pad. If you don't have a rocket with a motor mount meant for this than don't try it.
THe coupler is where the parachute is located and also where it will eject out of the rocket while the rocket is in the air. Written By: Amir Rasuli
It holds everything together.
A cardboard tube is most common