Concurrently with the development of the Sparrow I, 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 United States Navy service in 1958.
The AAM-N-6a was similar to the -6, but used a new Thiokol liquid-fuel rocket engine for improved performance. It also included changes to the guidance electronics to make it effective at higher closing speeds. The -6a was also selected to arm the Air Force's F-110A Spectre(F-4 Phantom) fighters in 1962, known to them as the AIM-101. It entered production in 1959, with 7500 being built.
Another upgrade reverted to a Rocketdyne solid-fuel motor for the AAM-N-6b, which started production in 1963. The new motor significantly increased maximum range to 35 kilometres (22 mi) for head-on attacks.
During this year the Navy and Air Force agreed on standardized naming conventions for their missiles. The Sparrows became the AIM-7 series. The original Sparrow I and aborted Sparrow II became the AIM-7A and AIM-7B, despite both being out of service. The -6, -6a and -6B became the AIM-7C, AIM-7D and AIM-7E respectively.
25,000 AIM-7Es were produced, and saw extensive use 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 (kill probability) of the AIM-7E was less than 10%; US fighter pilots shot down 55 aircraft using the Sparrow.
In 1969 an improved version, the E-2, was introduced with clipped wings and various changes to the fuzing. Considered a "dogfight Sparrow", the AIM-7E-2 was intended to be used at shorter ranges where the missile was still travelling at high speeds, and in the head-on aspect, making it much more useful in the visual limitations imposed on the engagements. Even so, its kill rate was only 13% in combat in 1972, leading to a practice of ripple-firing all four at once in hopes of increasing kill probability. Its worst tendency was that of detonating prematurely, approximately a thousand feet in front of the launching aircraft, but it also had many motor failures, erratic flights, and fuzing problems. An E-3 version included additional changes to the fuzing, and an E-4 featured a modified seeker for use with the F-14 Tomcat.
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 Alenia to develop advanced versions of Sparrow with better performance and improved electronics as the BAe Skyflash and Alenia Aspide, respectively.
The most common version of the Sparrow today, the AIM-7M, entered service in 1982 and featured a new inverse monopulse seeker (matching the capabilities of Skyflash), active radar fuse, digital controls, improved ECM resistance, and better low-altitude performance. It was used to good advantage in the 1991 Gulf War, where it scored many USAF air-to-air kills; its kill probability, overall, is still less than 40%.
The AIM-7P is similar in most ways to the M versions, and was primarily an upgrade program for existing M-series missiles. The main changes were to the software, improving low-level performance. A follow-on Block II upgrade added a new rear receiver allowing the missile to receive mid-course correction from the launching aircraft. Plans initially called for all M versions to be upgraded, but currently P's are being issued as required to replace M's lost or removed from the inventory.
The final version of the missile was to have been the AIM-7R, which added an infrared seeker to an otherwise unchanged AIM-7P Block II. A general wind-down of the budget led to it being cancelled in 1997.
Sparrow is now being phased out with the availability of the active-radar AIM-120 AMRAAM, but is likely to remain in service for several years.
-
AIM-7Es being loaded on a Hawaii ANG F-4C in 1980
-
AIM-7Fs on a 37th TFW F-4G in 1988
-
Wings being installed on an AIM-7
-
An AIM-7M being loaded
Read more about this topic: AIM-7 Sparrow, Development
Famous quotes containing the words sparrow and/or iii:
“Nature herself has not provided the most graceful end for her creatures. What becomes of all these birds that people the air and forest for our solacement? The sparrow seems always chipper, never infirm. We do not see their bodies lie about. Yet there is a tragedy at the end of each one of their lives. They must perish miserably; not one of them is translated. True, “not a sparrow falleth to the ground without our Heavenly Father’s knowledge,” but they do fall, nevertheless.”
—Henry David Thoreau (1817–1862)
“Napoleon wanted to turn Paris into Rome under the Caesars, only with louder music and more marble. And it was done. His architects gave him the Arc de Triomphe and the Madeleine. His nephew Napoleon III wanted to turn Paris into Rome with Versailles piled on top, and it was done. His architects gave him the Paris Opera, an addition to the Louvre, and miles of new boulevards.”
—Tom Wolfe (b. 1931)