| AIM-7 Sparrow | |
|---|---|
 AIM-7 Sparrow atHill Air Force Base Museum. | |
| Type | Medium-range, semi-active radar homing air-to-air missile |
| Place of origin | United States |
| Service history | |
| In service | 1958–present |
| Used by | Australia, Canada, Egypt, Greece, Iran, Iraq, Israel, Italy, Japan, Jordan, Kuwait, Malaysia, Saudi Arabia, Singapore, South Korea, Spain, Taiwan, Turkey, United Kingdom, United States |
| Wars | Vietnam War Gulf War |
| Production history | |
| Manufacturer | Raytheon |
| Unit cost | $125,000 |
| Produced | AIM-7D: 1959 AIM-7F: 1976 AIM-7M: 1982 |
| No. built | >70,000[1] |
| 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,AGM-45[2] |
| Specifications | |
| Mass | 510 lb (230 kg) |
| Length | 12 ft (3.7 m) |
| Diameter | 8 in (200 mm) |
| Wingspan | 2 ft 8 in (0.81 m) (AIM-7A/B) |
| Warhead | High explosiveblast-fragmentation AIM-7C/D/E: 65 pounds (29 kg) AIM-7F/M: 88 pounds (40 kg) |
| Engine | AIM-7A/B/C – Aerojet 1.8KS7800 solid rocket AIM-7D/E – Rocketdyne MK 38/MK 52 solid rocket AIM-7F/M/P – Hercules MK-58 solid-propellant rocket motor[3] |
Operational range | AIM-7C: 26 kilometres (14 nmi) AIM-7D: 44 kilometres (24 nmi) AIM-7E/E2: 50 kilometres (27 nmi) AIM-7F/M/P: 70 kilometres (38 nmi)[4][3] |
| Maximum speed | AIM-7A/B:Mach 2.5 AIM-7C/E/F: Mach 4[5] |
Guidance system | semi-active radar homing |
Launch platform | Aircraft: |
TheAIM-7 Sparrow (Air Intercept Missile[6]) is an American medium-rangesemi-active radar homingair-to-air missile operated by theUnited States Air Force,United States Navy,United States Marine Corps, and various other air forces and navies. Sparrow and its derivatives were the West's principalbeyond 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 advancedAIM-120 AMRAAM.[7]
The early Sparrow was intended primarily for use against larger targets, especially bombers, and had numerous operational limitations in other uses. Against smaller targets, the need to receive a strong reflected radar signal made it difficult to achievelock-on at the missile's effective range. As the launching aircraft's own radar needed to be pointed at the target throughout the engagement, this meant that in fighter-vs-fighter combat the enemy fighter would often approach within the range of shorter-rangeinfrared homing missiles while the launching aircraft had to continue flying towards its target. Additionally, early models were only effective against targets at roughly the same or higher altitudes, below which reflections from the ground became a problem.
A number of upgraded Sparrow designs were developed to address these issues. In the early 1970s, theRAF developed theSkyflash version with aninverse monopulse seeker[citation needed] and improved motor, while theItalian Air Force introduced the similarAspide. Both could be fired at targets below the launching fighter ("look-down, shoot-down"), were more resistant to countermeasures, and were much more accurate in the terminal phase. This basic concept then became part of the US Sparrows in the M model (for monopulse) and some of these were later updated as the P model, the last to be produced in the US. Aspides sold toChina resulted in the locally producedPL-11. TheJapan Self-Defense Forces also employ the Sparrow missile, though it is being phased out and replaced by theMitsubishi AAM-4.
The Sparrow was also used as the basis for asurface-to-air missile, theRIM-7 Sea Sparrow, used by a number of navies for air defense. Fired at low altitude and flying directly at its target, though, the range of the missile in this role is greatly reduced because of the higher air density of the lower atmosphere. With the retirement of the Sparrow in the air-to-air role, a new version of the Sea Sparrow was produced to address this concern, producing the larger and more capableRIM-162 ESSM.
The Sparrow emerged from a late-1940sUnited States Navy program to develop a guided rocket weapon for air-to-air use. In 1947 the Navy contractedSperry to build abeam-riding version of a standard 5-inch (127 mm)HVAR, the standard unguided aerial rocket, underProject Hotshot. The weapon was initially dubbedKAS-1, thenAAM-2, and — from 1948 on —AAM-N-2. The airframe was developed by theDouglas Aircraft Company. The diameter of the HVAR proved to be inadequate for the electronics, leading Douglas to expand the missile's airframe to 8-inch (203 mm) diameter. The prototype weapon began unpowered flight tests in 1947, and made its first aerial interception in 1952.[5]
After a protracted development cycle the initialAAM-N-2 Sparrow entered limited operational service in 1954 with specially modifiedDouglas F3D Skyknight all-weather carrier night fighters.[8] In 1956, they were joined by theMcDonnell F3H-2M Demon andVought F7U Cutlassfighter aircraft. Compared to the modern versions, the Sparrow I was more streamlined and featured a bullet-shaped airframe with a long pointed nose.
Sparrow I was a limited and rather primitive weapon. The limitations of beam-riding guidance (which was slaved to an optical sight on single-seater fighters and to radar on night fighters) restricted the missile to attacks against targets flying a straight course and made it essentially useless against a maneuvering target. Only about 2,000 rounds were produced to this standard.
As early as 1950, Douglas examined equipping the Sparrow with an active radar seeker, initially known asXAAM-N-2aSparrow II, the original retroactively becomingSparrow I. In 1952, it was given the new codeAAM-N-3. The active radar made the Sparrow II a "fire and forget" weapon, allowing several to be fired at separate targets at the same time.
By 1955, Douglas proposed going ahead with development, intending it to be the primary weapon for theF5D Skylancerinterceptor. It was later selected, with some controversy, to be the primary weapon for the CanadianAvro Arrow supersonic interceptor, along with the new Astra fire-control system. For Canadian use and as a second source for US missiles,Canadair was selected to build the missiles inQuebec.
The small size of the missile forebody and the K-band AN/APQ-64-radar limited performance, and it was never able to work in testing. After considerable development and test firings in the U.S. and Canada, Douglas abandoned development in 1956. Canadair continued development until the Arrow was cancelled in 1959.
Concurrently with the development of the Sparrow I, in 1951Raytheon began work on asemi-active radar-homing version, theAAM-N-6Sparrow III. The first of these weapons enteredUnited States Navy service in 1958.
TheAAM-N-6a was similar to the -6, and included changes to the guidance electronics to make it effective at higher closing speeds. It was originally designed to take theThiokol LR44-RM-2 liquid-fuel rocket motor, but the decision was made to retain the solid fuel rocket motor.[9][10] The -6a was also selected to arm the Air Force'sF-110A Spectre (F-4 Phantom) fighters in 1962, known to them as theAIM-101. It entered production in 1959, with 7500 being built.
With an improved Rocketdyne solid-fuel motor, theAAM-N-6b started production in 1963. The new motor significantly increased the maximum range to 35 kilometres (22 mi) for head-on attacks. This new missile also improved tail-on performance, with the AAM-N-6a being capable of firing on only targets with 300 ft/sec closing velocity, and AAM-N-6b being capable of firing on targets with a 300 knot opening velocity (-300 knot closing velocity or higher).[11]
During this year the Air Force and Navy agreed on standardized naming conventions for their missiles. The Sparrows became the AIM-7 series. The original Sparrow I and aborted Sparrow II became theAIM-7A andAIM-7B, despite both being out of service. The -6, -6a, and -6b became theAIM-7C,AIM-7D, andAIM-7E respectively.
25,000 AIM-7Es were produced and saw extensive use during theVietnam War, where its performance was 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 Pk (kill probability) of the AIM-7E was less than 10%; US fighter pilots shot down 59[Note 1] aircraft out of the 612 Sparrows fired.[12] Of the 612 AIM-7D/E/E-2 missiles fired, 97 (or 15.8%) hit their targets, resulting in 56 (or 9.2%) kills. Two kills were obtained beyond visual range.[13]
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, leading to a practice of ripple-firing all four at once in hopes of increasing kill probability. Its worst tendency was to detonate prematurely about 1,000 feet ahead 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 the E-4 featured a modified seeker for use with theF-14 Tomcat.
| Missile firing aircraft | Model | Aircraft shot down | Comments |
|---|---|---|---|
| F-4C Phantom II | AIM-7D | 1 MiG-17 | 555th Tactical Fighter Squadron (TFS) |
| F-4C | AIM-7E | 3 MiG-17s, 10 MiG-21s | 389th TFS,433rd TFS,480th TFS,555th TFS |
| F-4D | AIM-7E | 4 MiG-17s, 2 MiG-21s | 433rd TFS,435th TFS,555th TFS |
| F-4D | AIM-7E-2 | 18 MiG-21s, 3MiG-19s | 4th TFS,13th TFS,34th TFS,523rd TFS,555th TFS |
| F-4E | AIM-7E-2 | 8 MiG-21s, 1 MiG-19 | 4th TFS,35th TFS,58th TFS,366th TFS,555th TFS |
| Missile firing aircraft | Model | Aircraft shot down | Comments |
|---|---|---|---|
| F-4B Phantom II | AIM-7D | 4MiG-17s (includes 2 probables) | US fighters launched fromUSSRanger,USSMidway,USSCoral Sea |
| F-4B | AIM-7E | 2An-2 (AntonovBiplanes), 2MiG-21s, 1 MiG-17 | US fighters launched fromUSSConstellation andUSSEnterprise |
| F-4J | AIM-7E-2 | 1 MiG-21 | US fighters launched fromUSSSaratoga |
| Category | USAF | USN | Combined |
|---|---|---|---|
| An-2s | — | 2 | 2 |
| MiG-17s | 8 | 5 | 13 |
| MiG-19s | 4 | — | 4 |
| MiG-21s | 38 | 3 | 41 |
| Total | 50 | 10 | 60 |
Work began in the mid 1960s on a new version in an attempt to address the weapon's limitations. TheAIM-7F, which entered service in 1976, had a dual-stage rocket motor for longer range andsolid-state electronics for greatly improved reliability. The reduction in volume from the new guidance system also enabled a larger warhead to be fitted, improving the missile's lethality.
The issues encountered by AIM-7 were not exclusive to the US either, with bothBritish Aerospace and the Italian firmSelenia developing improved missiles at the behest of their national governments as theBAe Skyflash andSelenia Aspide. Notably, both missiles incorporated more reliableinverse monopulse seekers, a feature American AIM-7s would not gain until the 1980s.
The most common version of the Sparrow today, theAIM-7M, entered service in 1982 and featured a new inverse monopulse seeker (matching the capabilities of Skyflash and Aspide), active radarproximity fuse, digital controls, improvedECM resistance, and better low-altitude performance. It was used to good advantage in the 1991Gulf War, where it scored many USAF air-to-air kills. Of 44 missiles fired, 30 (68.2%) hit their intended targets resulting in 24/26 (54.5%/59.1%) kills. 19 kills were obtained beyond visual range.[15]
TheAIM-7P is similar in most ways to the M versions, and was primarily an upgrade for existing M-series missiles. Changes were mainly 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.[citation needed] 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.[citation needed]
The U.S. Navy planned to operate the missile through 2018.[16]
The Sparrow is now being phased out with the availability of the active-radarAIM-120 AMRAAM, but is likely to remain in service for several years.[when?][citation needed]
| AAM-N-2 (AIM-7A) | AAM-N-3 (AIM-7B) | AIM-7C | AIM-7E | AIM-7F | AIM-7M/P | RIM-7M/P | |
|---|---|---|---|---|---|---|---|
| Length | 3.74 m (147.3 in) | 3.85 m (151.7 in) | 3.66 m (144 in) | ||||
| Wingspan | 0.94 m (37 in) | 1.02 m (40 in) | |||||
| Finspan | 0.88 m (34.8 in) | ? | 0.81 m (32 in) | 0.62 m (24.3 in) | |||
| Diameter | 0.203 m (8 in) | ||||||
| Weight | 143 kg (315 lb) | 176 kg (389 lb) | 172 kg (380 lb) | 197 kg (435 lb) | 231 kg (510 lb) | ||
| Speed | Mach 2.5 | Mach 4 | |||||
| Range | 10 km (5.4 nm) | 7 km (4 nm) | 11 km (6 nm) | 30 km (16 nm) | 70 km (38 nm) | 26 km (14 nm) | |
| Propulsion | Aerojet1.8KS7800 solid rocket | Rocketdyne MK 38/MK 52 solid rocket | Hercules MK 58 dual-thrust solid rocket | ||||
| Warhead | 20 kg (45 lb) | 30 kg (65 lb) MK 38 continuous rod | 39 kg (86 lb) MK 71 continuous rod | 40 kg (88 lb) WDU-27/B blast-fragmentation | |||
Sparrow X was a subvariant of the Sparrow I armed with the same nuclear warhead as theMB-1 Genie was proposed in 1958 but was cancelled shortly thereafter.
AIM-7F Multishot was a proposal under the US Navy's F-4X program of the 1960s to equip the then under development missiles and their launch platforms with a datalink fortrack-via-missile guidance akin to that ofAIM-54 Phoenix, which would enable multiple AIM-7 missiles to be guided simultaneously. As each missile would only need terminal illumination from the F-4's radar, it could engage multiple aircraft simultaneously as long as it kept all targets within view of its radar.[18] As this modification would have required all-new solid state electronics for theAN/AWG-10 radars on the launching F-4s, it was not pursued.
AIM-7R was to add aninfrared homing seeker to an otherwise unchanged AIM-7P Block II. A general wind-down of the budget led to it being cancelled in 1997.
As part of theAvro Canada CF-105 Arrow program, Canadair (nowBombardier) partnered withDouglas Aircraft Company in the development of the Sparrow II (AAM-N-3/AIM-7B). After Douglas dropped out of this program,Canadair continued on with it until the termination of the Arrow project.
The AAM-N-3 Sparrow II was unique in that it had a fullyactive radar guidance system.[1] This combined both a radar transmitter and receiver in the missile, making it unnecessary for the pilot to keep the aircraft aimed at the target after firing the missile,[19] unlikeSemi-active radar homing (SARH) missiles which require continuous radar-assisted guidance throughout flight. This allowed the aircraft that fired the AAM-N-3 to turn away, prosecute other targets, and/or escape from potential retaliatory missiles fired by the enemy aircraft during the time it took for the Sparrow to reach its target. Despite the significant advantages of this design over SARH guidance, all subsequent models of the Sparrow usesemi-active radar homing.
To accommodate the active radar guidance system, the AAM-N-3 Sparrow II had a much greater volume than its predecessor. Its size would subsequently set the precedent for all future Sparrow variants.[1]
In 1959, Canadair had completed five missiles based on airframes from Douglas, and built two models from scratch, when the program was cancelled with the cancellation of the Arrow.[19]
The Italian company Selenia (nowLeonardo S.p.A.) licensed the AIM-7E Sparrow technology from the US, and produced its own version.Later in the 1970s, Alenia started to produce an improved version of the AIM-7 called the Aspide. Compared to the AIM-7E, it received an improved new monopulse guidance system that allowed for a better hit ratio and easier targeting of enemies at low altitude with ground-clutter confusion.It also received a new and more powerful engine and new control surfaces. These control surfaces were each independent of the others, giving the missile greatly improved maneuverability over the AIM-7E and the British Skyflash that still used dependent control surfaces.[20]
The PL-11 andHQ-6 are a family of Chinese missiles developed by the Shanghai Academy of Science and Technology, largely based on the Italian Aspide version of the Sparrow missile.[21][22]
The Soviet Union acquired an AIM-7 in 1968 and aVympel team started copying it as theK-25. The missile did not enter production as theR-23 was thought to have better versatility, range, signal processing logic, and immunity to interference. K-25 work ended in 1971, but analysis of the Sparrow was later used to inform the design of theVympel R-27, particularly the servomechanisms and movable wings.[23]
British Aerospace (BAe) licensed the AIM-7E-2 technology in the 1970s, producing theSkyflash missile. Skyflash used a Marconi XJ521 monopulse seeker together with improvements to the electronics. It was powered by the Aerojet Mk52 mod 2 rocket engine (later by the Rocketdyne Mk38 mod 4). Skyflash entered service with theRoyal Air Force (RAF) on theirPhantom FG.1 & FGR.2 in 1978, and later on theTornado F.3. Skyflash was also exported to Sweden for use on theirViggen fighters.
An upgraded version with active radar seeker calledActive Sky Flash was proposed by BAe andThomson-CSF, but the RAF opted to procureAIM-120 AMRAAM instead.[24]
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 thecontinuous-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.
The launching aircraft illuminates the target with its radar. In 1950s radars, these were single-target tracking devices using anutating horn as part of the antenna, thereby sweeping the beam in a small cone. Signal processing is applied to determine the direction of maximum illumination, thereby developing 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-pointingwaveguides. The comparison of these two signals enabled logic circuits to determine the true target reflection signal, even if the target were to eject radar-reflectingchaff.
Related development
