RIM-7 Sea Sparrow
Encyclopedia
RIM-7 Sea Sparrow is a US ship-borne short-range anti-aircraft and anti-missile weapon system, primarily intended for defense against anti-ship missile
s. The system was developed in the early 1960s from the AIM-7 Sparrow
air-to-air missile
as a lightweight "point defense
" weapon that could be retrofitted to existing ships as quickly as possible, often in place of existing gun-based anti-aircraft weapons. In this incarnation it was a very simple system, guided by a manually aimed radar illuminator. Since its introduction, the Sea Sparrow has undergone significant development and now resembles the AIM-7 only in general form; it is larger, faster and includes a new seeker and a launch system suitable for vertical launch from modern warships. Fifty years after its development, the Sea Sparrow remains an important part of a layered air defense system, providing a short/medium-range component especially useful against sea-skimming missiles.
s or torpedo bomber
s, whose low speed allowed them to be attacked with anti-aircraft guns. The advantage was so great that when the Royal Navy
was faced by the threat of the new Soviet Sverdlov class cruiser
, they responded in a non-linear fashion by introducing the Blackburn Buccaneer
aircraft to attack them.
Further improving the capabilities of aircraft against ships were a variety of precision-guided weapons
, starting with World War II
manually-controlled weapons such as the Fritz X
, and evolving into semi-autonomous cruise missile
s, such as the Raduga KS-1 Komet
, that relied on a combination of initial guidance from the launching aircraft and terminal guidance on the missile itself. These systems allowed the aircraft to launch their attacks from outside the range of shipboard weapons, in relative safety. Only the presence of defensive fighters operating at long ranges from the ships could provide cover against these attacks, by attacking the launch aircraft before they could close on the ships.
US Navy doctrine stressed long-range air cover to counter both high-speed aircraft and missiles, and development of newer short range defenses had been largely ignored. While developing expensive long-range fighters like the Douglas F6D Missileer, most ships were left equipped with older weapons, typically Bofors 40 mm gun
s or similar weapons. By the early 1960s their capability against modern aircraft and missiles was limited; a lack of fast-reacting mounts, gunsight radars of limited accuracy and long settling times for the fire control systems all meant that the guns were unlikely to be able to respond effectively.
The introduction of sea-skimming missiles
dramatically increased the threat of ASMs against these ships. Unlike the earlier generation of ASMs, sea-skimmers approached at low level, like an attack aircraft, hiding themselves until the last moment. The missiles were relatively small and much harder to hit than an attacking aircraft. While the older defenses might be considered a credible threat to a large aircraft or a missile approaching at higher altitudes, against a sea-skimming missile they were useless. To successfully counter this threat, ships needed new weapons able to attack these targets as soon as they appeared, accurately enough to give them a high first-attempt kill probability - there would be little time for a second attempt.
In 1959 the Army started development of the MIM-46 Mauler
, which mounted a new high-speed missile on top of the ubiquitous M113 Armored Personnel Carrier
chassis, along with a medium-range search radar and a separate tracking and illumination radar. In order to deal with the quick response times needed, the fire control system was semi-automatic; operators would view targets on the search radar and prioritize them, the fire control system would select ones within attack range and automatically slew the missiles toward them and launch. Since the missile would be operating close to the ground in highly cluttered environments, it used a combination of beam riding
along the illumination radar and an infrared seeker in the nose, which allowed tracking as long as either the path in front or in rear of the missile remained free of obstructions.
These same basic engagement parameters - high-speed and the associated fleeting sighting times - applied to sea-skimming aircraft and missiles as well. The Navy intended to adapt the Mauler to shipboard use by removing its search radar and wiring it into the existing ship-borne radar systems instead. The 9-box launcher and illuminator radar would be retained in a relatively compact mount. Development started in 1960 under the "Point Defense Missile System" (PDMS), the naval version to be known as the "RIM-46A Sea Mauler". The Navy was so confident in the Sea Mauler that they modified the design of their latest frigates, the Knox class
, to incorporate a space on the rear deck for the Sea Mauler launcher.
The Navy's confidence in Mauler proved misplaced; by 1963 the program had been downgraded to a pure technology development effort due to continued problems, and was canceled outright in 1965. All three of the stakeholders, the US Army, US Navy and British Army
, started looking for a replacement. While the British took a longer-term approach and developed the new Rapier missile
, the US Army and Navy scrambled to find a system that could be deployed as quickly as possible. Facing the problem of guidance in a cluttered environment, the Army decided to adapt the infrared AIM-9 Sidewinder
missile into the MIM-72 Chaparral. This was based on the AIM-9D, a tail-chaser, and would be useless for the Navy where its targets would be approaching head on. They required a radar-guided system, and this naturally led to the AIM-7 Sparrow. They also considered Chaparral for smaller ships due to its much smaller size, but no such fits were ever attempted.
Quickly organizing the "Basic Point Defense Missile System", BPDMS, the then-current AIM-7E from the F-4 Phantom was adapted to shipboard use with surprising speed. The main developments were the new Mark 25 trainable launcher developed from the ASROC
launcher, and the Mark 115 manually aimed radar illuminator that looked like two large searchlight
s. Operation was extremely simple; the operator would be cued to targets via voice commands from the search radar operators, and he then slewed the illuminator onto the target. The relatively wide beam of the radar only needed to be in the general direction of the target, the continuous wave signal being Doppler shifted by the moving target and showing up strongly even if it was not centered in the beam. The launcher would automatically follow the motions of the illuminator, so that when the missile was fired it would immediately see the signal being reflected off the target.
In this form the Sea Sparrow was tested on the USS Bradley
starting in February 1967, but this installation was removed when the Bradley was sent to Vietnam
later that year. Testing continued, and between 1971 and 1975 Sea Sparrow was fitted to 31 ships, DE-1052 to 1069
and DE-1071
to 1083
. The "missing ship" in the series, USS Downes
(DE-1070) was instead used to test an upgraded version (see below).
The Sea Sparrow was far from an ideal weapon. Its rocket engine was designed with the assumption that it would be launched at high speed from an aircraft, and therefore is optimized for a long cruise at relatively low power. In the surface-to-air role one would rather have very high acceleration in order to allow it to intercept sea-skimming targets as soon as possible. The power profile is also suitable for cruising in thin air at high altitudes, but at low altitudes it does not produce enough power to overcome drag and dramatically decreases range; some estimates indicate that the Sea Sparrow may be effective only to 10 kilometres (6.2 mi), about one quarter of the range of the air-launched Sparrow. An engine of much higher power would greatly improve performance, in spite of a shorter burning time.
Another problem is that the Sparrow is steered with its mid-mounted maneuvering wings. These were used on the Sparrow because they required less energy for basic maneuvers during cruise, but this made the missile less maneuverable overall, which was not well suited to the quick-reaction weapon. Additionally, the powered wings meant that they could not easily be adapted to fold, and therefore the launcher cells were sized to the wings instead of the missile body, taking up much more room than required. Although the Sea Sparrow was meant as a small missile system that could be fit to a wide variety of ships, the launcher was relatively large and was deployed only to larger frigates, destroyers and aircraft carriers. Finally, the manually-aimed illuminator was of limited use at night or in bad weather, which was hardly encouraging for a ship-borne weapon where fog was a common occurrence.
, Italy
, and Norway
signed an agreement with the US Navy to use the Sea Sparrow on their ships, and collaborate on improved versions. Over the next few years a number of other countries joined the NATO SEASPARROW Project Office (NSPO), and today it includes 12 member nations. Under this umbrella group, the "Improved Basic Point Defense Missile System" (IBPDMS) program started even while the original version was being deployed.
IBPDMS emerged as the RIM-7H, which was essentially the RIM-7A with the mid-mounted wings modified to be able to fold. This was done in a fashion similar to carrier-based aircraft; the wings were hinged at a point about 50% along the span, with the outer portions rotated back toward the body of the missile. This allowed them to be stored in tighter container tubes in the new Mark 29 launcher, and flip open automatically when they were released from the tube.
The seeker was modified to work with a variety of guidance radars, including those being used with existing European missile systems. Production of the RIM-7H began in 1973 as NATO Sea Sparrow Missile System (NSSMS) Block I. For the US Navy's use the new MK-95 illuminator system was also introduced, similar to the original Mark 115 but with automatic guidance that could be used in any weather. The MK-95 formed the basis of the highly automated Mark 91 fire control system.
, producing the AIM-7F. The F model replaced the older analog guidance system with a solid state
version that could operate with the F-15's new pulse-doppler radar. The guidance system was much smaller, which allowed the warhead to be moved from its former rear-mounted position to one in front of the mid-mounted wings, and increased in weight to 86 lbs (39 kg). Moving it forward also allowed the rocket engine to be enlarged, so it was replaced by a new dual-thrust engine that quickly accelerated the missile to higher speeds, and then settled to a lower thrust for cruise. The new missiles were quickly adapted for the naval role in a fashion similar to the RIM-7H, producing the RIM-7F. The new missile used the lower model designation in spite of the newer technology than the H model.
Another major upgrade to the AIM-7 followed, the AIM-7M. The M included a new monopulse radar
seeker that allowed it to be shot downward from a higher-altitude aircraft at a target otherwise masked by the ground. The new model also included a completely computerized guidance system that could be updated in the field, as well as further reducing weight for yet another warhead upgrade. The computerized guidance system also included a simple autopilot that allowed the missile to continue flying toward the last known target location even with the loss of a signal, allowing the launch platform to break lock for short periods while the missile was in flight. All of these modifications also improved performance against low-altitude sea-skimming targets as well. The M model entered US operational service in 1983.
While the M model was being worked on, the US Navy also introduced an upgrade for the Mark 91 fire control system, the "Mark 23 Target Acquisition System" (TAS). TAS included a medium-range 2D radar and IFF
system that fed information to a new console in the ship's combat information center
. The Mark 23 automatically detected, prioritized and displayed potential targets, greatly improving reaction times of the system as a whole. The Mark 23 is also used to select targets for most other weapons systems, including gunfire and other missile systems. TAS started entering the fleet in 1980.
The NSPO also used the M series upgrade as an opportunity to upgrade the system to allow it to be launched from a Vertical Launching System
(VLS). This modification uses the "Jet Vane Control" (JVC) package that is added to the bottom of the missile. On launch, a small engine in the JVC boosts the missile up above the launching ship, then uses vanes positioned in its own exhaust to quickly slew the missile into the proper alignment with the target, which is fed to the JVC during launch. As far as the Sea Sparrow is concerned, there is no difference between being launched directly from a trainable launcher or using JVC, in both cases the missile becomes active looking directly at the target.
A final upgrade to the Sparrow was the AIM-7P, which replaced the M's guidance system with an improved model that allowed mid-course upgrades to be sent from the launching platform via new rear-mounted antennas. For air-to-air use this allowed the missile to be "lofted" above the target and then be directed down towards it as it approached; this gives the missile greater range as it spends more time in thinner high-altitude air. This meant that the new version could also be directly guided against surface targets that would otherwise not show up well on radar (which is a function of relative speed), allowing the ship's more powerful search radars to provide guidance until the missile approached the target and the reflected signal grew stronger. This also gave the Sea Sparrow a very useful secondary anti-shipping role that allows it to attack smaller boats.
On 1 October 1992 during NATO exercises in the Aegean Sea
the USS Saratoga
accidentally launched two Sea Sparrow missiles. These hit the Turkish destroyer TCG Muavenet in the bridge and CIC
, killing five of the ship's officers and injuring twenty-two men. The Muavenet was written off as a result, and the US presented them with the Knox class frigate
USS Capodanno
as reparations.
Although the Navy and Air Force initially planned additional upgrades for the Sparrow, notably the AIM-7R with a combination radar/infrared seeker, these were canceled in favor of the much more advanced AIM-120 AMRAAM
in December 1996. With the link between the airborne and shipborne versions of the Sparrow severed, Raytheon proposed a much more extensive set of upgrades to the Sea Sparrow, the RIM-7R Evolved Sea Sparrow Missile (ESSM). The changes were so extensive that the project was renamed, becoming the RIM-162 ESSM.
The ESSM takes the existing guidance section from the RIM-7P and fits it to an entirely new rear-section. The new missile is 10 inches in diameter instead of the previous 8 inches, which allows for a much more powerful motor. It also eliminates the mid-mounted wings entirely, replacing them with long fins similar to those on the Standard missile
(and practically every other Navy missile since the 1950s) and moves guidance control to the rear fins. The tail-fin based steering of the ESSM uses up more energy but offers considerably higher maneuverability while the engine is still firing.
A new Mark 25 quad-missile pack was developed to fit four ESSMs into a single Mark 41 VLS cell. For VLS use, ESSMs are fitted with the same JVC system as the earlier versions.
Italy
Anti-ship missile
Anti-ship missiles are guided missiles that are designed for use against ships and large boats. Most anti-ship missiles are of the sea-skimming type, many use a combination of inertial guidance and radar homing...
s. The system was developed in the early 1960s from the AIM-7 Sparrow
AIM-7 Sparrow
The AIM-7 Sparrow is an American, 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...
air-to-air missile
Air-to-air missile
An air-to-air missile is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...
as a lightweight "point defense
Point-defence
Point-defence is the defence of a single object or a limited area, e.g. a ship, building or an airfield, now usually against air attacks and guided missiles...
" weapon that could be retrofitted to existing ships as quickly as possible, often in place of existing gun-based anti-aircraft weapons. In this incarnation it was a very simple system, guided by a manually aimed radar illuminator. Since its introduction, the Sea Sparrow has undergone significant development and now resembles the AIM-7 only in general form; it is larger, faster and includes a new seeker and a launch system suitable for vertical launch from modern warships. Fifty years after its development, the Sea Sparrow remains an important part of a layered air defense system, providing a short/medium-range component especially useful against sea-skimming missiles.
Background
High-speed jet aircraft approaching ships at low altitudes presented a serious threat to naval forces in the late 1950s. Approaching under the local horizon of the ships, the aircraft would suddenly appear at relatively close ranges, giving the ships only seconds to respond before the aircraft dropped their payloads and withdrew. This gave the aircraft an enormous advantage over earlier weapons such as dive bomberDive bomber
A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy for the bomb it drops. Diving towards the target reduces the distance the bomb has to fall, which is the primary factor in determining the accuracy of the drop...
s or torpedo bomber
Torpedo bomber
A torpedo bomber is a bomber aircraft designed primarily to attack ships with aerial torpedoes which could also carry out conventional bombings. Torpedo bombers existed almost exclusively prior to and during World War II when they were an important element in many famous battles, notably the...
s, whose low speed allowed them to be attacked with anti-aircraft guns. The advantage was so great that when the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
was faced by the threat of the new Soviet Sverdlov class cruiser
Sverdlov class cruiser
The Sverdlov class cruisers, Soviet designation Project 68bis, were the last conventional cruisers built for the Soviet Navy; 13 ships were completed before Nikita Khrushchev called a halt to the programme as these ships were considered obsolescent with the advent of the guided missile...
, they responded in a non-linear fashion by introducing the Blackburn Buccaneer
Blackburn Buccaneer
The Blackburn Buccaneer was a British low-level subsonic strike aircraft with nuclear weapon delivery capability serving with the Royal Navy and the Royal Air Force between 1962 and 1994, including service in the 1991 Gulf War...
aircraft to attack them.
Further improving the capabilities of aircraft against ships were a variety of precision-guided weapons
Precision-guided munition
A precision-guided munition is a guided munition intended to precisely hit a specific target, and to minimize damage to things other than the target....
, starting with World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
manually-controlled weapons such as the Fritz X
Fritz X
Fritz X was the most common name for a German guided anti-ship glide bomb used during World War II. Fritz X was a nickname used both by Allied and Luftwaffe personnel. Alternate names include Ruhrstahl SD 1400 X, Kramer X-1, PC 1400X or FX 1400...
, and evolving into semi-autonomous cruise missile
Cruise missile
A cruise missile is a guided missile that carries an explosive payload and is propelled, usually by a jet engine, towards a land-based or sea-based target. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy...
s, such as the Raduga KS-1 Komet
Raduga KS-1 Komet
The Raduga KS-1 Komet , also referred to as AS-1 and KS-1 was a short range air-to-surface missile developed by the Soviet Union, and carried only on the Tupolev Tu-4K 'Bull' and, more notably, on the Tupolev Tu-16 'Badger'.Development was begun in 1947 along with a related ground-launched...
, that relied on a combination of initial guidance from the launching aircraft and terminal guidance on the missile itself. These systems allowed the aircraft to launch their attacks from outside the range of shipboard weapons, in relative safety. Only the presence of defensive fighters operating at long ranges from the ships could provide cover against these attacks, by attacking the launch aircraft before they could close on the ships.
US Navy doctrine stressed long-range air cover to counter both high-speed aircraft and missiles, and development of newer short range defenses had been largely ignored. While developing expensive long-range fighters like the Douglas F6D Missileer, most ships were left equipped with older weapons, typically Bofors 40 mm gun
Bofors 40 mm gun
The Bofors 40 mm gun is an anti-aircraft autocannon designed by the Swedish defence firm of Bofors Defence...
s or similar weapons. By the early 1960s their capability against modern aircraft and missiles was limited; a lack of fast-reacting mounts, gunsight radars of limited accuracy and long settling times for the fire control systems all meant that the guns were unlikely to be able to respond effectively.
The introduction of sea-skimming missiles
Sea skimming
Sea skimming is a technique many anti-ship missiles use to avoid radar and infrared detection during their approach.-Method:Sea skimming anti-ship missiles try to fly as low as is practically achievable, which is almost always below 50 meters , and is often down towards 5 meters .-Advantages:By...
dramatically increased the threat of ASMs against these ships. Unlike the earlier generation of ASMs, sea-skimmers approached at low level, like an attack aircraft, hiding themselves until the last moment. The missiles were relatively small and much harder to hit than an attacking aircraft. While the older defenses might be considered a credible threat to a large aircraft or a missile approaching at higher altitudes, against a sea-skimming missile they were useless. To successfully counter this threat, ships needed new weapons able to attack these targets as soon as they appeared, accurately enough to give them a high first-attempt kill probability - there would be little time for a second attempt.
Point defence missile system (PDMS)
The US Army faced a similar problem defending against attacks by high-speed jet-powered attack aircraft. In this case the local horizon was generally even more limited, blocked by trees and hills, and engagement times could be measured in seconds. They concluded that a gun-based system was simply unusable in this role; by the time the radar had locked-on and the gunsight calculated proper "lead" there would be no time to shoot at the target while it was within a gun's relatively short range. Missiles, on the other hand, could progressively tune their approach while they were flying toward the target, and their proximity fuses meant they only needed to get "close enough".In 1959 the Army started development of the MIM-46 Mauler
MIM-46 Mauler
The General Dynamics MIM-46 Mauler was a self-propelled anti-aircraft missile system designed to a late 1950s US Army requirement for a system to combat low-flying high-performance tactical fighters and short-range ballistic missiles...
, which mounted a new high-speed missile on top of the ubiquitous M113 Armored Personnel Carrier
M113 Armored Personnel Carrier
The M113 is a fully tracked armored personnel carrier that has formed the backbone of the United States Army's mechanized infantry units from the time of its first fielding in Vietnam in April 1962. The M113 was the most widely used armored vehicle of the U.S...
chassis, along with a medium-range search radar and a separate tracking and illumination radar. In order to deal with the quick response times needed, the fire control system was semi-automatic; operators would view targets on the search radar and prioritize them, the fire control system would select ones within attack range and automatically slew the missiles toward them and launch. Since the missile would be operating close to the ground in highly cluttered environments, it used a combination of beam riding
Beam riding
Beam-riding, also known as beam guidance, is a technique of directing a missile to its target by means of radar or a laser beam. The name refers to the way the missile flies down the guidance beam, which is aimed at the target...
along the illumination radar and an infrared seeker in the nose, which allowed tracking as long as either the path in front or in rear of the missile remained free of obstructions.
These same basic engagement parameters - high-speed and the associated fleeting sighting times - applied to sea-skimming aircraft and missiles as well. The Navy intended to adapt the Mauler to shipboard use by removing its search radar and wiring it into the existing ship-borne radar systems instead. The 9-box launcher and illuminator radar would be retained in a relatively compact mount. Development started in 1960 under the "Point Defense Missile System" (PDMS), the naval version to be known as the "RIM-46A Sea Mauler". The Navy was so confident in the Sea Mauler that they modified the design of their latest frigates, the Knox class
Knox class frigate
Knox class frigates were United States Navy warships, originally laid down as ocean escorts , but were all redesignated as frigates on 30 June 1975 in the USN 1975 ship reclassification and their hull designation changed from DE to FF.A sub-class of the Knox class was built, commonly referred to as...
, to incorporate a space on the rear deck for the Sea Mauler launcher.
The Navy's confidence in Mauler proved misplaced; by 1963 the program had been downgraded to a pure technology development effort due to continued problems, and was canceled outright in 1965. All three of the stakeholders, the US Army, US Navy and British Army
British Army
The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...
, started looking for a replacement. While the British took a longer-term approach and developed the new Rapier missile
Rapier missile
Rapier is a British surface-to-air missile developed for the British Army and Royal Air Force. Entering service in 1971, it eventually replaced all other anti-aircraft weapons in Army service; guns for low-altitude targets, and the English Electric Thunderbird, used against longer-range and...
, the US Army and Navy scrambled to find a system that could be deployed as quickly as possible. Facing the problem of guidance in a cluttered environment, the Army decided to adapt the infrared AIM-9 Sidewinder
AIM-9 Sidewinder
The AIM-9 Sidewinder is a heat-seeking, short-range, air-to-air missile carried mostly by fighter aircraft and recently, certain gunship helicopters. The missile entered service with United States Air Force in the early 1950s, and variants and upgrades remain in active service with many air forces...
missile into the MIM-72 Chaparral. This was based on the AIM-9D, a tail-chaser, and would be useless for the Navy where its targets would be approaching head on. They required a radar-guided system, and this naturally led to the AIM-7 Sparrow. They also considered Chaparral for smaller ships due to its much smaller size, but no such fits were ever attempted.
Basic point defence missile system (BPDMS)
ASROC
ASROC is an all-weather, all sea-conditions anti-submarine missile system. Developed by the United States Navy in the 1950s, it was deployed in the 1960s, updated in the 1990s, and eventually installed on over 200 USN surface ships, specifically cruisers, destroyers, and frigates...
launcher, and the Mark 115 manually aimed radar illuminator that looked like two large searchlight
Searchlight
A searchlight is an apparatus that combines a bright light source with some form of curved reflector or other optics to project a powerful beam of light of approximately parallel rays in a particular direction, usually constructed so that it can be swiveled about.-Military use:The Royal Navy used...
s. Operation was extremely simple; the operator would be cued to targets via voice commands from the search radar operators, and he then slewed the illuminator onto the target. The relatively wide beam of the radar only needed to be in the general direction of the target, the continuous wave signal being Doppler shifted by the moving target and showing up strongly even if it was not centered in the beam. The launcher would automatically follow the motions of the illuminator, so that when the missile was fired it would immediately see the signal being reflected off the target.
In this form the Sea Sparrow was tested on the USS Bradley
USS Bradley (FF-1041)
USS Bradley was the second of ten 2,620-ton Garcia-class destroyer escort ships, later reclassified as frigates, in the United States Navy. She was named for Captain Willis Winter Bradley, Jr....
starting in February 1967, but this installation was removed when the Bradley was sent to Vietnam
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
later that year. Testing continued, and between 1971 and 1975 Sea Sparrow was fitted to 31 ships, DE-1052 to 1069
USS Bagley (FF-1069)
USS Bagley was a Knox-class frigate of the United States Navy. She was the 18th ship of the Knox class, built as a destroyer escort and redesignated as a frigate in the 1975 USN ship reclassification...
and DE-1071
USS Badger (FF-1071)
USS Badger was a Knox-class destroyer escort, originally designated as DE-1071 and reclassified as a frigate in 1975 in the United States Navy. Her primary mission of ASW remained unchanged. This ship was not the first to bear the name. The first was named for Commodore Oscar C...
to 1083
USS Cook (FF-1083)
The USS Cook was a Knox class frigate built for the United States Navy by Avondale Shipyard, Westwego, Louisiana. Her keel was laid 20 March 1970, she was launched 23 January 1971 and delivered 9 December 1971. Cook was commissioned 18 December 1971 and decommissioned 30 April 1992...
. The "missing ship" in the series, USS Downes
USS Downes (FF-1070)
USS Downes was the 19th in the series of the Knox class frigates. She was the third ship to be named for Commodore John Downes...
(DE-1070) was instead used to test an upgraded version (see below).
The Sea Sparrow was far from an ideal weapon. Its rocket engine was designed with the assumption that it would be launched at high speed from an aircraft, and therefore is optimized for a long cruise at relatively low power. In the surface-to-air role one would rather have very high acceleration in order to allow it to intercept sea-skimming targets as soon as possible. The power profile is also suitable for cruising in thin air at high altitudes, but at low altitudes it does not produce enough power to overcome drag and dramatically decreases range; some estimates indicate that the Sea Sparrow may be effective only to 10 kilometres (6.2 mi), about one quarter of the range of the air-launched Sparrow. An engine of much higher power would greatly improve performance, in spite of a shorter burning time.
Another problem is that the Sparrow is steered with its mid-mounted maneuvering wings. These were used on the Sparrow because they required less energy for basic maneuvers during cruise, but this made the missile less maneuverable overall, which was not well suited to the quick-reaction weapon. Additionally, the powered wings meant that they could not easily be adapted to fold, and therefore the launcher cells were sized to the wings instead of the missile body, taking up much more room than required. Although the Sea Sparrow was meant as a small missile system that could be fit to a wide variety of ships, the launcher was relatively large and was deployed only to larger frigates, destroyers and aircraft carriers. Finally, the manually-aimed illuminator was of limited use at night or in bad weather, which was hardly encouraging for a ship-borne weapon where fog was a common occurrence.
Improved basic point defense missile system (IBPDMS)
In 1968, DenmarkDenmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, and Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
signed an agreement with the US Navy to use the Sea Sparrow on their ships, and collaborate on improved versions. Over the next few years a number of other countries joined the NATO SEASPARROW Project Office (NSPO), and today it includes 12 member nations. Under this umbrella group, the "Improved Basic Point Defense Missile System" (IBPDMS) program started even while the original version was being deployed.
IBPDMS emerged as the RIM-7H, which was essentially the RIM-7A with the mid-mounted wings modified to be able to fold. This was done in a fashion similar to carrier-based aircraft; the wings were hinged at a point about 50% along the span, with the outer portions rotated back toward the body of the missile. This allowed them to be stored in tighter container tubes in the new Mark 29 launcher, and flip open automatically when they were released from the tube.
The seeker was modified to work with a variety of guidance radars, including those being used with existing European missile systems. Production of the RIM-7H began in 1973 as NATO Sea Sparrow Missile System (NSSMS) Block I. For the US Navy's use the new MK-95 illuminator system was also introduced, similar to the original Mark 115 but with automatic guidance that could be used in any weather. The MK-95 formed the basis of the highly automated Mark 91 fire control system.
Missile upgrades
In 1972 Raytheon started a Sparrow upgrade program to arm the upcoming F-15 EagleF-15 Eagle
The McDonnell Douglas F-15 Eagle is a twin-engine, all-weather tactical fighter designed by McDonnell Douglas to gain and maintain air superiority in aerial combat. It is considered among the most successful modern fighters with over 100 aerial combat victories with no losses in dogfights...
, producing the AIM-7F. The F model replaced the older analog guidance system with a solid state
Solid state (electronics)
Solid-state electronics are those circuits or devices built entirely from solid materials and in which the electrons, or other charge carriers, are confined entirely within the solid material...
version that could operate with the F-15's new pulse-doppler radar. The guidance system was much smaller, which allowed the warhead to be moved from its former rear-mounted position to one in front of the mid-mounted wings, and increased in weight to 86 lbs (39 kg). Moving it forward also allowed the rocket engine to be enlarged, so it was replaced by a new dual-thrust engine that quickly accelerated the missile to higher speeds, and then settled to a lower thrust for cruise. The new missiles were quickly adapted for the naval role in a fashion similar to the RIM-7H, producing the RIM-7F. The new missile used the lower model designation in spite of the newer technology than the H model.
Another major upgrade to the AIM-7 followed, the AIM-7M. The M included a new monopulse radar
Monopulse radar
Monopulse radar is an adaptation of conical scanning radar which sends additional information in the radar signal in order to avoid problems caused by rapid changes in signal strength. The system also makes jamming more difficult...
seeker that allowed it to be shot downward from a higher-altitude aircraft at a target otherwise masked by the ground. The new model also included a completely computerized guidance system that could be updated in the field, as well as further reducing weight for yet another warhead upgrade. The computerized guidance system also included a simple autopilot that allowed the missile to continue flying toward the last known target location even with the loss of a signal, allowing the launch platform to break lock for short periods while the missile was in flight. All of these modifications also improved performance against low-altitude sea-skimming targets as well. The M model entered US operational service in 1983.
While the M model was being worked on, the US Navy also introduced an upgrade for the Mark 91 fire control system, the "Mark 23 Target Acquisition System" (TAS). TAS included a medium-range 2D radar and IFF
Identification friend or foe
In telecommunications, identification, friend or foe is an identification system designed for command and control. It is a system that enables military and national interrogation systems to identify aircraft, vehicles, or forces as friendly and to determine their bearing and range from the...
system that fed information to a new console in the ship's combat information center
Combat Information Center
The Operations Room is the tactical center of a warship or AWAC aircraft providing processed information for command and control of the near battle space or 'area of operations'...
. The Mark 23 automatically detected, prioritized and displayed potential targets, greatly improving reaction times of the system as a whole. The Mark 23 is also used to select targets for most other weapons systems, including gunfire and other missile systems. TAS started entering the fleet in 1980.
The NSPO also used the M series upgrade as an opportunity to upgrade the system to allow it to be launched from a Vertical Launching System
Vertical Launching System
A vertical launching system is a system for holding and firing missiles on surface ships and submarines used by many navies around the world. Each VLS system consists of a number of cells, which can hold one or more missiles ready for firing...
(VLS). This modification uses the "Jet Vane Control" (JVC) package that is added to the bottom of the missile. On launch, a small engine in the JVC boosts the missile up above the launching ship, then uses vanes positioned in its own exhaust to quickly slew the missile into the proper alignment with the target, which is fed to the JVC during launch. As far as the Sea Sparrow is concerned, there is no difference between being launched directly from a trainable launcher or using JVC, in both cases the missile becomes active looking directly at the target.
A final upgrade to the Sparrow was the AIM-7P, which replaced the M's guidance system with an improved model that allowed mid-course upgrades to be sent from the launching platform via new rear-mounted antennas. For air-to-air use this allowed the missile to be "lofted" above the target and then be directed down towards it as it approached; this gives the missile greater range as it spends more time in thinner high-altitude air. This meant that the new version could also be directly guided against surface targets that would otherwise not show up well on radar (which is a function of relative speed), allowing the ship's more powerful search radars to provide guidance until the missile approached the target and the reflected signal grew stronger. This also gave the Sea Sparrow a very useful secondary anti-shipping role that allows it to attack smaller boats.
On 1 October 1992 during NATO exercises in the Aegean Sea
Aegean Sea
The Aegean Sea[p] is an elongated embayment of the Mediterranean Sea located between the southern Balkan and Anatolian peninsulas, i.e., between the mainlands of Greece and Turkey. In the north, it is connected to the Marmara Sea and Black Sea by the Dardanelles and Bosporus...
the USS Saratoga
USS Saratoga (CV-60)
USS Saratoga , was one of four Forrestal- class supercarriers built for the US Navy in the 1950s. Saratoga was the sixth US Navy ship, and the second aircraft carrier, to be named for the Battle of Saratoga in the American Revolutionary War.Commissioned in 1956, she spent most of her career in...
accidentally launched two Sea Sparrow missiles. These hit the Turkish destroyer TCG Muavenet in the bridge and CIC
Combat Information Center
The Operations Room is the tactical center of a warship or AWAC aircraft providing processed information for command and control of the near battle space or 'area of operations'...
, killing five of the ship's officers and injuring twenty-two men. The Muavenet was written off as a result, and the US presented them with the Knox class frigate
Knox class frigate
Knox class frigates were United States Navy warships, originally laid down as ocean escorts , but were all redesignated as frigates on 30 June 1975 in the USN 1975 ship reclassification and their hull designation changed from DE to FF.A sub-class of the Knox class was built, commonly referred to as...
USS Capodanno
USS Capodanno (FF-1093)
USS Capodanno was the 42nd Knox class frigate in the United States Navy. It was named after Fr. Vincent Capodanno, recipient of the Medal of Honor....
as reparations.
Evolved Sea Sparrow missile (ESSM)
AIM-120 AMRAAM
The AIM-120 Advanced Medium-Range Air-to-Air Missile, or AMRAAM , is a modern beyond-visual-range air-to-air missile capable of all-weather day-and-night operations. Designed with the same form-factor as the previous generation of semi-active guided Sparrow missiles, it is a fire-and-forget...
in December 1996. With the link between the airborne and shipborne versions of the Sparrow severed, Raytheon proposed a much more extensive set of upgrades to the Sea Sparrow, the RIM-7R Evolved Sea Sparrow Missile (ESSM). The changes were so extensive that the project was renamed, becoming the RIM-162 ESSM.
The ESSM takes the existing guidance section from the RIM-7P and fits it to an entirely new rear-section. The new missile is 10 inches in diameter instead of the previous 8 inches, which allows for a much more powerful motor. It also eliminates the mid-mounted wings entirely, replacing them with long fins similar to those on the Standard missile
Standard missile
Standard Missile can refer to a family of several different American missiles:* RIM-66 Standard , a medium range surface-to-air missile, the successor of the RIM-24 Tartar missile...
(and practically every other Navy missile since the 1950s) and moves guidance control to the rear fins. The tail-fin based steering of the ESSM uses up more energy but offers considerably higher maneuverability while the engine is still firing.
A new Mark 25 quad-missile pack was developed to fit four ESSMs into a single Mark 41 VLS cell. For VLS use, ESSMs are fitted with the same JVC system as the earlier versions.
Operators
- Royal Australian NavyRoyal Australian NavyThe Royal Australian Navy is the naval branch of the Australian Defence Force. Following the Federation of Australia in 1901, the ships and resources of the separate colonial navies were integrated into a national force: the Commonwealth Naval Forces...
Italy- Mexican NavyMexican NavyThe Mexican Navy is the naval branch of the Mexican military responsible for conducting naval operations. Its stated mission is "to use the naval force of the federation for the exterior defense, and to help with internal order". The Navy consists of about 56,000 men and women plus reserves, over...
- Republic of Korea NavyRepublic of Korea NavyThe Republic of Korea Navy or the ROK Navy is the branch of the South Korean armed forces responsible for conducting naval operations and amphibious landing operations. The ROK Navy includes the Republic of Korea Marine Corps, which is a quasi-autonomous organization...
- Royal New Zealand NavyRoyal New Zealand NavyThe Royal New Zealand Navy is the maritime arm of the New Zealand Defence Force...
- United States NavyUnited States NavyThe United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
See also
- List of missiles
- Missile designationMissile designationThe U.S. Department of Defense established a missile and rocket designation sequence, which is used in all weapons of the kind produced in the USA.-Explanation:The basic designation of every guided missile is based in a set of letters, which are in sequence...