THERMAL JET PROPULSION SYSTEM.-

Thermal jets include solid propellant, liquid propellant, and combined propellant systems. As an AO, you come in contact with all three systems, The solid propellant and combined propellant systems are currently being used in some air-launched guided missiles.

The majority of air-launched guided missiles used by the Navy use the solid propellant rocket motor. They include the double-base and multibase smokeless powder propellants as well as the composite mixtures. Grain configurations vary with the different missiles. Power characteristics and temperature limitations of the individual rocket motors also vary.

In some guided missiles, different thrust requirements exist during the boost phase as compared to those of the sustaining phase. The dual thrust rocket motor (DTRM) is a combined system that contains both of these elements in one motor. The DTRM contains a single propellant grain made of two types of solid propellant-boost and sustaining. The grain is configured so the propellant meeting the requirements for the boost phase burns at a faster rate than the propellant for the sustaining phase. After the boost phase propellant burns itself out, the sustaining propellant sustains the motor in flight over the designed burning time (range of the missile).

Figure 3-6.-AIM-7F/M Sparrow missile.

SERVICE GUIDED MISSILES

Missiles have been operational for several years. Still, research on missiles continuously produces changes in the missile field. The missiles discussed in this manual are presently operational.

Sparrow III Guided Missile

The AIM-7F/M missile (fig. 3-6) is a supersonic, air-to-air DTRM, guided missile. It is designed to be rail or ejection launched from an interceptor aircraft. The missile's tactical mission is to intercept and destroy enemy aircraft in all-weather environments. It is designed to be launched from the F-14 and F/A-18 aircraft.

The AIM-7F/M missile is a semiactive missile. Missile guidance depends on RF energy radiated by the launching aircraft and reflected by the target. Excluding the radome, the missile body has four sectional tubular shells that house the major functional components. The four major functional components are the target seeker, flight control, warhead, and rocket motor. The overall length of the missile is approximately 142 inches with a diameter of 8 inches. It weighs approximately 510 pounds. The missile is issued to the fleet as an all-up-round (AUR). The only assembly required at fleet level is the installation of the wing and fin assemblies, which are shipped in separate shipping containers.

The radome is ceramic and forms the nose piece of the missile. It does not obstruct RF energy. It covers the RF head assembly of the target seeker and provides protection against environmental damage.

The target seeker receives and interprets the radar energy reflected from the target. Then it produces signals that are sent to the flight control section to direct the missile to intercept the target or come within lethal range of it.

The flight control consists of the autopilot and the hydraulic group. These function to provide control signals and mechanical energy to move the external control surfaces that guide the missile toward the point of intercept, and to stabilize the missile in pitch, yaw, and roll.

The warhead is located between the target seeker and flight control section. The warhead is explosive-loaded, and it contains the fuze, fuze booster charge, and the safety and arming (S&A) device. It is a continuous-rod type of warhead. At detonation, the rod sections expand into a continuous ring. Target kill is accomplished by collision of the continuous ring with the target. Detonation is triggered either by a fuze pulse from the target seeker at the nearest point of intercept or a fuze pulse from the flight control upon impact with the target,

The DTRM attaches to the aft end of the missile flight control section. It is equipped with a SAFE/ARM igniter assembly that is manually locked in either the SAFE or ARMED position. This switch can only be repositioned with an arming key. When in the SAFE position, the arming key cannot be removed. This switch prevents accidental firing of the motor. It should not be moved to the ARMED position until immediately before aircraft launch.

The control surfaces consist of four delta-shaped wing and fin assemblies. The wings and fins are designed for quick attachment and release without the use of tools. The wing assemblies attach to the flight control section, which controls their rotary motion to produce the desired pitch, yaw, and roll. The tail fin assemblies attach to fittings on the rear of the rocket motor and provide stability to the missile.

Another series of the Sparrow III guided missile is the RIM-7E and RIM-7H. These missiles are surface-to-air guided missiles. They are used in some ships in the ship's Basic Point Defense Surface Missile System (BPDSMS) and Improved Point Defense Surface Missile System (IPDSMS), respectively. As an Aviation Ordnanceman, your responsibility for these missiles is in the area of handling and stowage only.

For further information concerning the Sparrow III (series) missiles, refer to publication organizational, Intermediate, and Depot Maintenance Instruction Manual with Illustrated Parts Breakdown, NAVAIR 01-265GMAD-9-3 (series).

Harpoon Guided Missile

The Harpoon surface attack guided missile, AGM-84 series (AGM-84/C/D Tactical) air-launched

missile (fig. 3-7), is an all-weather antiship attack weapon. The SLAM tactical missile (fig. 3-7), AGM-84E, is a standoff land attack missile. The Harpoon can be delivered from the A-6, F/A-18, P-3, and S-3 aircraft. The SLAM primary launch platforms are the A-6E and F/A-18 aircraft. Both missiles are AURs and require no assembly other than installation of the wing and control fin assemblies. The missile consists of the guidance section, warhead section, sustainer section, boattail section, wings, and control fins. The missile is approximately 151 inches in length and weighs approximately 1,144 pounds.

The Harpoon missile has a low-level cruise trajectory with over-the-horizon range that makes it less susceptible to radar detection. It uses active guidance and has counter-countermeasure capability.

The guidance section contains the seeker, radar altimeter, midcourse guidance unit, and power supply. A radome on the front of the guidance section provides

Figure 3-7.-AGM-84 series Harpoon/SLAM guided missile. 3-10

the required aerodynamic shield to protect the internal components of the seeker. During ground handling, the radome is protected by a radome protector cap.

The warhead section contains a penetration blast type of explosive, the guided missile fuze, fuze booster, and the pressure probe assembly. It also provides internal routing of the interconnecting cable from the guidance section to other parts of the missile.

The sustainer section contains the fuel tank and fuel supply system, missile battery, pyrotechnic relay panel, and the turbojet engine. Three BSU-4/B missile wings and one BSU-43/B missile wing are attached to the sustainer section by quick-attach, clevis-type fittings. These wings are attached to the missile at the organizational level. They provide the aerodynamic lift required to sustain missile flight. They are made of a framed aluminum honeycomb construction and are nonfolding.

The boattail section contains four control actuators, which control the control fins. Four identical nonfolding missile control fins (BSU-44/B) provide directional control of the missile's airframe proportional to the input signal received from the guidance section. The control fins are one-piece aluminum castings, and are attached to the control fin actuators by means of an integral torque-limiting, screw-type device.

For further information concerning the air-launched AGM-84 (series) Harpoon guided missiles, refer to the publications Airborne Weapons Assembly, NAVAIR 11-140-6.2-4, and Airborne Weapons Assembly, AGM-84/E, NAVAIR 11-140-6.2-5.