The propellant tank occupies a large part of the space of the arrow body, and it is used to store propellant. A rocket with two-component propellant has two tanks, one containing oxidant and the other containing combustion agent. If one-component propellant is used, one case is enough. At present, the propellant tanks of most launch vehicles are not only used to store propellant, but also a part of the load-bearing structure of rocket bodies. Propellant tank should be sealed, and no leakage is allowed after loading propellant. At present, the commonly used material is weldable aluminum alloy. Materials used as propellant tanks must be compatible with stored propellants. The so-called compatibility means that the two can be harmonious: on the one hand, the material can resist the corrosion of the propellant, on the other hand, the material has no physical and chemical effect on the propellant and does not change the chemical composition or quality of the propellant. The tank body is generally cylindrical, with two tank bottoms at the front and rear, and a cylindrical shell part in the middle. Two tank bottoms and shell parts are welded into a cylindrical container. In order to shorten the length of the whole rocket, some launch vehicles connect the oxidizer tank and the combustion agent tank into a whole, separated by a bottom (called * * * bottom); Others use a circular water tank like a lifebuoy. There is a connecting section between two independent cylindrical tanks, which is called the inter-tank section. Using the space between boxes, some instruments or equipment can be installed, and the explosive devices of safety self-destruction systems are often placed here.
Instrument cabin is a cabin where instruments and equipment of control system and other systems are installed centrally. At present, the instrument cabin of launch vehicle is often arranged near the front end of the arrow body, far from the engine. The vibration is small, which is beneficial to instruments and equipment.
Thrust structure is a load-bearing component used to install the engine and transfer thrust to the arrow. There are two common thrust structures: frame structure and semi-hard shell structure. Frame thrust structure is also called engine frame.
The tail section is at the last part of the arrow body, so it is called the tail section. It is not only an engine compartment, but also plays a supporting role when the whole rocket is erected on the launch pad. Some launch vehicles are equipped with a tail besides the tail, while others are not. The tail plays a role in stabilizing the rocket flight. According to the aerodynamic stability of the rocket body when the launch vehicle flies in the atmosphere, it can be decided whether to install the tail wing when designing the control system scheme.
The tandem multistage rocket also has an interstage section, which is the connection place between stages, that is, the separation part between stages. There are two stages of separation, one is called thermal separation, that is, the upper stage rocket is ignited first and then separated from the poles; One is called cold separation, that is, first separate the two poles and then ignite the upper stage rocket. For rockets with thermal separation, the interstage structure is often adopted, so that the flame of the upper stage engine can be discharged smoothly before separation.