MISSILE COMPONENTS

Guided missiles are made up of a series of subassemblies (figs. 3-1 and 3-2). The various subassemblies form a major section of the overall missile to operate a missile system, such as guidance, control, armament (warhead and fuzing), and propulsion. The major sections are carefully joined and connected to each other. They form the complete missile assembly. The arrangement of major sections in the missile assembly varies, depending on the missile type.

The guidance section is the brain of the missile. It directs its maneuvers and causes the maneuvers to be executed by the control section. The armament section carries the explosive charge of the missile, and the fuzing and firing system by which the charge is exploded. The propulsion section provides the force that propels the missile.

Guidance and Control Section

The complete missile guidance system includes the electronic sensing systems that initiate the guidance

Figure 3-1.-Typica1 air-to-air guided missile. 3-4

Figure 3-2.-Typical air-to-surface guided missile.

orders and the control system that carries them out. The elements for missile guidance and missile control can be housed in the same section of the missile, or they can be in separate sections.

There are a number of basic guidance systems used in guided missiles. Homing-type, air-launched, guided missiles are currently used. They use radar or infrared homing systems.

A homing guidance system is one in which the missile seeks out the target, guided by some physical indication from the target itself. Radar reflections or thermal characteristics of targets are possible physical influences on which homing systems are based. Homing systems are classified as active, semiactive, and passive.

ACTIVE.- In the active homing system, target illumination is supplied by a component carried in the

Figure 3-3.-Active homing system.

missile, such as a radar transmitter. The radar signals (fig. 3-3) transmitted from the missile are reflected off the target back to the receiver in the missile. These reflected signals give the missile information such as the target's distance and speed. This information lets the guidance section compute the correct angle of attack to intercept the target. The missile's angle of attack is controlled by the control section that receives electronic commands from the guidance section. Mechanically manipulated wings, fins, or canard control surfaces are mounted externally on the body of the weapon. They are actuated by hydraulic, electric, or gas generator power, or combinations of these to alter the missile's course.

SEMIACTIVE.- In the semiactive homing system (fig. 3-4), the missile gets its target illumination from an external source, such as a transmitter carried in the launching aircraft. The receiver in the missile

Figure 3-4.-Semiactive homing system.

Figure 3-5.-Passive honing system.

receives the signals reflected off the target, computes the information, and sends electronic commands to the control section. The control section functions in the same manner as previously discussed.

PASSIVE.- In the passive homing system (fig. 3-5), the directing intelligence is received from the target. Examples of passive homing include homing on a source of infrared rays (such as the hot exhaust of jet aircraft) or radar signals (such as those transmitted by ground radar installations). Like active homing, passive homing is completely independent of the launching aircraft. The missile receiver receives signals generated by the target, and then the missile control section functions in the same manner as previously discussed.