AIM-7 Sparrow
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Development
The Sparrow emerged from a late-1940s US Navy program to develop a guided rocket weapon for air-to-air use. In 1947 the Navy contracted Sperry to build a beam-riding version of a standard 5-inch (127 mm) HVAR, the standard unguided aerial rocket. The weapon was initially dubbed KAS-1, then AAM-2, and, from 1948 on, AAM-N-2. The airframe was developed by Douglas Aircraft. The diameter of the HVAR proved to be inadequate for the electronics, leading Douglas to expand the missile's airframe to 8 in (203 mm) diameter. The prototype weapon made its first aerial interception in 1952.
After a protracted development cycle the initial AAM-N-2 Sparrow I entered service in 1956, carried by the F3H-2M Demon and F7U Cutlass fighter aircraft.
Sparrow I was a limited and rather primitive weapon. The limitations of beam-riding guidance (which was slaved to an optical sight, requiring visual identification of the target) restricted the missile to visual-range attacks and made it essentially useless against a maneuvering target. Only about 2,000 rounds were produced to this standard.
In 1951, Douglas began development a much more advanced Sparrow II, designated AAM-N-3, which would have used active radar homing (with the missile carrying its own internal radar). The Sparrow II was the second version of the Sparrow airframe and introduced the trapazoidal main wing replacing the triangular wing of the Sparrow I. This was considered for the F5D Skylancer interceptor and for the abortive Avro Arrow, but the missile proved to be beyond the state of the art for the mid-1950s, and was cancelled before entering service. Technically, the limited range of its K-band seeker reduced its use.
Concurrently, in 1951, Raytheon began work on the semi-active radar homing version of Sparrow family of missiles, the AAM-N-6 Sparrow III. The first of these weapons entered US Navy service in 1958. About 2,000 were produced before production switched to the AAM-N-6a (later redesignated AIM-7D after 1963, with an improved rocket motor, and the AAM-N-6b (later AIM-7E).
Although initially a US Navy weapon, the AAM-N-6b Sparrow was adopted by the USAF in 1962, initially designated AIM-101. After 1963 both services adopted the AIM-7 designation for the Sparrow.
The AIM-7 was used extensively during the Vietnam War, where its performance was generally considered disappointing. The mixed results were a combination of reliability problems (exacerbated by the tropical climate), limited pilot training in fighter-to-fighter combat, and restrictive rules of engagement that generally prohibited BVR (beyond visual range) engagements. The P&subk; (kill probability) of the AIM-7E was less than 10%.
Improved versions of the AIM-7 were developed in the 1970s in an attempt to address the weapon's limitations. The AIM-7F, which entered service in 1976, had a dual-stage rocket motor for longer range, solid-state electronics for greatly improved reliability, and a larger warhead. Even this version had room for improvement, leading British Aerospace and the Italian firm Selenia to develop advanced versions of Sparrow as the BAe Skyflash and Selenia Aspide, respectively.
The ultimate version of the Sparrow, the AIM-7M, with a new inverse monopulse seeker (matching the capabilities of Skyflash), active radar fuse, digital controls, improved ECM resistance, and better low-altitude performance, entered service in 1982. It was used to good advantage in the 1991 Gulf War, where it scored many USAF air-to-air kills.
Sparrow is now being phased out with the availability of the active-radar AIM-120 AMRAAM, but is likely to remain in service for a number of years.
Description
The 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.
Specifications (AIM-7M)
- Length: 12 ft (3600 mm)
- Diameter: 8 in (203 mm)
- Wingspan: 2 ft 8 in (81 mm)
- Launch weight: 510 lb (231 kg)
- Speed: Mach 4
- Range: 44 mi (70 km)
- Guidance: semi-active radar homing
- Warhead: 88 lb (40 kg) blast fragmentation
See also
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