Raytheon AIM-7M/P Sparrow III

The AIM-7 Sparrow missile (AIM - Aerial Intercept Missile) has been the premier medium range air-to-air missile for the US Air Force since entering production in 1972. In the Gulf War, the AIM-7 Sparrow proved to be a very potent air-to-air weapon. 22 Iraqi fixed-wing aircraft and three Iraqi helicopters were downed by radar-guided AIM-7 Sparrow missiles.

The AIM-7 is a typical loadout on F-15 air-superiority versions (F-15A/C) but is a rarely seen weapon on F-15E Strike Eagle aircraft.

Only when used on rather uncommon air-superiority missions, the F-15E carries the AIM-7 on its CFT´s internal weapons rows. Up to four AIM-7 missiles can be attached to the aircraft´s weapons stations LCT-1/LCT-3 and RCT-1/RCT-3 in combination with the LAU-106 ejector launcher. The AIM-7 is too heavy to be launched from the underwing LAU-128/A rail launchers.

The F-15E uses the AIM-7M missile, which entered service in 1982, and the improved AIM-7P missile, which is currently built by new production as well as conversion of existing AIM-7M missiles.

The AIM-7M version has an inverse monopulse semi-active seeker which, with digital processing, greatly improves the missile´s performance under heavy ECM and weather conditions. It also has the advantage of an active radar fuze, which together with the built-in test system has provided a more reliable missile, capable of attacking low-flying aircraft targets.

The AIM-7P missile has improved guidance electronics, a new fuze and an onboard computer with twice the capacity and speed of the current models. It also has the capability to receive mid-course uplink information in the same formats used by the AIM-54 Phoenix, AIM-120 AMRAAM and AGM-78 Standard missiles.

System Description

The AIM-7 Sparrow is a radar-guided, semi-active air-to-air missile. It does not transmit a radar beam like active missiles and does not guide itself from emissions from the target like a passive missile would.

The semi-active AIM-7 guides on RF energy radiated by the F-15E´s AN/APG-70 Radar and deflected by the enemy aircraft. During its supersonic boost-and-glide flight, the missile receives radar data from the F-15E´s fire control system via its rear signal receiver and also receives reflected RF energy from the target via its own internal radar receiver (front signal).

The incoming signals from both the rear receiver and the front radar receiver is processed by the Missile Borne Computer (MBC) located in the guidance section of the missile. A comparison of these signals allows the MBC to sence changes in target position and create signals used by the autopilot, located in the control section, to control movement of the wings and thus maintain course to target intercept.

The autopilot sends guidance command signals to the hydraulic control group. The hydraulic control group uses the hydraulic power supplied by an accumulator to move the four delta platform wings located on the hub assembly of the control section in response to the guidance command signals from the autopilot.

The missile´s wings guide the missile toward the "point of intercept" and stabilize the missile in pitch, yaw, and roll. Missile stability is also provided by four fixed delta fins, which are located on the rear of the missile in line with the forward wings.

The blast fragmentation type warhead assembly is located between the guidance section and the control section. The Save-Arm-Device (SAD) in the warhead assembly is electrically connected with the guidance section by a SAD cable. At the nearest point of intercept, the active RF fuzing circuit in the guidance sections sends a fuze pulse to the warhead´s SAD, which ignites the fuze booster. The fuze booster detonates and finally ignites the main warhead charge. Detonation is also triggered by an impact switch located in the control section.

The AIM-7M/P missile has a WDU-27/B fixed-focus blast fragmentation warhead with a metal casing around the explosive charge. The inside of the metal casing is notched to provide the necessary amount of shrapnel.

The AIM-7 missile incorporates Electronic-Counter-Countermeasure (ECCM) capabilities, also known as Electronic Protection (EP), to defeat countermeasures by the target such as jamming.

Missile Components

Excluding the radome, the cylindrical body of the AIM-7 missile has four major sections (from front to rear): guidance section, warhead, control section and rocket motor.

The ceramic radome forms the nosepiece of the missile and covers the RF head assembly of the target seeker.

The guidance section includes the Missile Borne Computer (MBC), a tunnel cable to the control section, forward antenna, target and rear receivers, a radar fuze unit, and electric gimbaled motors.

The warhead assembly includes the main explosive charge (40 kg / 88 lb), a MK-38 Mod 2 fuze booster and the Save-Arm-Device (SAD). The MK-38 Mod 2 fuze booster is designed to melt rather than detonate when exposed to extensive heat, providing additional safety to ordnance personnel and fire fighters.

The MK-58 Mods 2, 3 and 5 rocket motor assemblies of the AIM-7 series are dual-thrust, solid propellant propulsion units. The rocket motor assembly consists of a case with propellant grain, a safe-arm ignition assembly with an Arm-Fire-Device (AFD) relock assembly and a nozzle weather seal at the rear. The AFD relock T-handle locks in either the SAFE or ARM position and cannot be removed from the missile when in the SAFE position. It is used to arm the rocket motor manually immediately before flight.

The AIM-7´s wings and fins are designed for quick attachment and release without the use of tools. The delta platform wings attach to the hub assembly of the control section while the delta fins mount to dovetail quick-attach fittings on the rear of the missile.

Specifications

Primary Function: Radar-guided medium-range air-to-air missile
Manufacturer: Raytheon Co.
Guidance System: Raytheon semi-active on either continuous wave or pulsed Doppler radar energy
Warhead: 40 kg (88 lb) WDU-27/B blast-fragmentation
Propulsion: Hercules MK-58 solid-propellant rocket motor by ATK Tactical Systems
Thrust: Classified
Speed: Mach 4
Range: 45 km (24 nm)
Length: 3.66 m (144 in)
Wingspan: 1.02 m (40 in)
Finspan: 0.81 m (32 in)
Diameter: 0.203 m (8 in)
Launch Weight: 231 kg (510 lb)
Unit Cost: Approximately US$ 125,000
Inventory: Classified