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Air-to-Air Missiles: AIM-7 Sparrow
The AIM-7 Sparrow is a supersonic air-to-air missile that uses semi-active radar to strike targets at medium range. The U.S. Air Force, Marine Corps, and Navy use the Sparrow, as do allied nations. The AIM-7 is a beyond-visual-range (BVR) missile used starting in the late 1950s up to the 1990s, when the AIM-120 AMRAAM was introduced. First developed as a guided rocket weapon for the U.S. Navy, the Sparrow underwent many refinements and upgrades during its decades of service.
AIM-7 Sparrow Air-to-Air Missile Development
In the late 1940s the U.S. Navy wanted a guided rocket for use in air-to-air combat. Sperry was contracted to develop a missile based on a standard 5-inch HVAR (high-velocity aircraft rocket). Douglas Aircraft provided the airframe for the missile, which was first designated the KAS-1, then the AAM-2, and after 1948, the AAM-N-2. Douglas had to increase the airframe to 8 inches in diameter to create space for the missile's electronics.
Testing began in 1948 with unpowered flight tests, and the first aerial interception was successfully made in 1952. A further four years of development were needed before the AAM-N-2 Sparrow entered service in 1956. But this first Sparrow, now known as the Sparrow I, was a simple, limited missile. It used beam-riding guidance, requiring visual-range attacks, and performed poorly against a maneuvering target.
Douglas worked on improving the Sparrow I, developing an active radar missile first designated the XAAM-N-2a Sparrow II. In 1952 the new missile, capable of operating as a fire-and-forget weapon, was designated the AAM-N-3. The missile's size and poor radar performance led to its being abandoned.
Raytheon started development of a semi-active radar version of the Sparrow in 1951. Called the AAM-N-6 Sparrow III, this missile entered service with the U.S. Navy in 1958. The AAM-N-6a variant used a new Thiokol liquid-fueled rocket engine for better performance. The Air Force adopted the AAM-N-6a for its F-110A Spectre (also known as the F-4 Phantom), redesignating the missile as the AIM-101. A total of 7500 AAM-N-6a Sparrows were built starting in 1959.
In 1963 the Sparrow saw two key developments in its history. First, the AAM-N-6b reverted to the Rocketdyne solid-fuel motor, increasing the missile's maximum range to 22 miles. Second, the Air Force and Navy agreed to standardize designations for missiles. The Sparrow was designated the AIM-7, with the Sparrow I becoming the AIM-7A, and the Sparrow II, the AIM-7B. The AAM-N-6 became the AIM-7C; the AAM-N-6a, the AIM-7D; and the AAM-N-6b, the AIM-7E. The AIM-7E Sparrow was used extensively during the Vietnam War, with approximately 25,000 missiles manufactured.
The AIM-7E2 was introduced in 1969, with changes to the fusing and clipped wings designed for better performance in dogfights. Although performance improved to a kill probability of 13 pct in 1972, the missile still had problems. It often detonated prematurely, and experienced motor failures, fusing problems, and uneven flight. An E-3 version was introduced with further changes to the fusing. The E-4 version had a modified seeker for use with the F-14 Tomcat.
In the 1970s further improvements were made to the Sparrow. A dual-stage rocket motor was added to increase range, solid-state electronics were used to improve reliability, and a larger warhead was adopted. The result was the AIM-7F, which began service in 1976 as the primary medium-range missile for the F-15 Eagle.
The Sparrow underwent more redesign in the early 1980s. An inverse monopulse seeker, active radar fuse, better ECM resistance, and digital controls were added, resulting in the AIM-7M, which entered service in 1982. Additional upgrades to the M series became the AIM-7P, which includes better software and low-level performance.
The AIM-7 Sparrow remains in use on aircraft such as the F/A-18 Hornet, F/A-18 Super Hornet, F-14 Tomcat, and F-15 Eagle, but is being phased out in favor of the AIM-120 AMRAAM.
AIM-7 Sparrow Operational History
The AAM-N-2 Sparrow I (AIM-7A) began service in 1956 with the F3H-2M Demon and F7U-3M Cutlass fighters. It was quickly superseded by the AIM-7B, which first entered service in 1958 with the U.S. Navy.
The AIM-7E saw considerable use during the Vietnam War. Due to limited fighter pilot training for air-to-air engagements, restrictive rules of engagement, and reliability issues, the Sparrow performed poorly, with a kill probability of less than 10 pct. Because of its limited performance, pilots often engaged in ripple-firing all four of their missiles in order to increase the change of hitting an enemy target.
The Sparrow recorded its first combat kill on 7 June 1965, when Navy F-4B Phantoms shot down two MiG-17s. A total of 55 aircraft were shot down using Sparrows in Vietnam.
The AIM-7M was used extensively during the Gulf War in 1991 by the U.S. Air Force. It was responsible for many air-to-air kills, though its kill probability remained under 40 pct.
Characteristics of the AIM-7 Sparrow (A and B variants)
Note: Characteristics change slightly depending on the AIM-7 variant.
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