The AIM-7 Sparrow is an American-made, medium-range semi-active radar homing air-to-air missile operated by the United States Air Force, United States Navy and United States Marine Corps, as well as various allied air forces and navies. Sparrow and its derivatives were the West's principal beyond visual range (BVR) air-to-air missile from the late 1950s until the 1990s. It remains in service, although it is being phased out in aviation applications in favor of the more advanced AIM-120 AMRAAM. The armed forces of Japan employ the Sparrow missile, though it is being phased out and replaced by the Mitsubishi AAM-4. NATO pilots use the brevity code Fox One in radio communication to signal launch of a Semi-Active Radar Homing Missile such as the Sparrow.
The AIM-7 Sparrow was used as the basis for a surface-to-air missile, the RIM-7 Sea Sparrow, which is used by the United States Navy for air defense of its ships.
| AIM-7 Sparrow | |
|---|---|
 | |
| Type | Medium-Range, Semi-Active Radar Homing Air-to-Air Missile |
| Place of origin | United States |
| Service history | |
| Used by | United States, Canada, South Korea, Turkey, Japan, Iran,Israel, Italy, United Kingdom, Saudi Arabia, Pakistan, Poland ,Thailand |
| Production history | |
| Manufacturer | Raytheon |
| Unit cost | $125,000 |
| Produced | AIM-7D: 1959 AIM-7F: 1976 AIM-7M: 1982 |
| Variants | Sparrow I: AIM-7A Sparrow II: AIM-7B Sparrow III: AIM-7C, AIM-7D, AIM-7E, AIM-7E2/Skyflash/Aspide, AIM-7F, AIM-7M, AIM-7P, RIM-7M |
| Specifications | |
| Weight | 510 lb (230 kg) |
| Length | 12 ft (3.7 m) |
| Diameter | 8 in (200 mm) |
| | |
| Warhead | High explosive blast-fragmentation AIM-7F/M: 88 pounds (40 kg) |
| | |
| Engine | Hercules MK-58 solid-propellant rocket motor |
| Wingspan | 2 ft 8 in (0.81 m) (AIM-120A/B) |
| Operational range | AIM-7C/D: 32 kilometres (20 mi) AIM-7E/E2: 45 kilometres (28 mi) AIM-7F/M: 50 kilometres (31 mi) |
| Speed | AIM-7A/B: Mach 2.5 AIM-7C/E/F: Mach 4 |
| Guidance system | semi-active radar |
| Launch platform | Aircraft:
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AIM-7 Sparrow Design
The AIM-7 Sparrow has four major sections: guidance section, warhead, control, and rocket motor (currently the Hercules MK-58 solid-propellant rocket motor). It has a cylindrical body with four wings at mid-body and four tail fins. Although the external dimensions of the Sparrow remained relatively unchanged from model to model, the internal components of newer missiles represent major improvements, with vastly increased capabilities. The warhead is of the continuous-rod type.
As with other semi-active radar guided missiles, the missile does not generate radar signals, but instead homes in on reflected continuous-wave signals from the launch platform's radar. The receiver also senses the guidance radar to enable comparisons that enhance the missile's resistance to passive jamming.
Principle of guidance (semi-active version)
The launching aircraft will illuminate the target with its radar. In radars of the 1950s these were single target tracking devices using a nutating horn as part of its antenna. This caused the beam to be swept in a small cone. Signal processing would be applied to determine the direction of maximum illumination and so develop a signal to steer the antenna toward the target. The missile detects the reflected signal from the target with a high gain antenna in a similar fashion and steers the entire missile toward closure with the target. The missile guidance also samples a portion of the illuminating signal via rearward pointing waveguides. The comparison of these two signals enabled logic circuits to determine the true target reflection signal, even if the target were to eject radar-reflecting chaff.
