This article was originally published in the January 2004 issue of Ordnance magazine, "Farewell to tomcats" series of articles. This reprint has been re-improved and edited, supplemented and sorted out by the secondary content, so as to share with the same friends. Personally, I think that "Weapons" magazine is a professional and objective military magazine, and it is recommended to continue to subscribe to enrich their military knowledge. Reprinting some of the older articles on them is mainly to let readers examine the things and opinions of the past from another and more unique perspective.
F-14A fighter jets equipped with the U.S. Navy VF-103 squadron launch AIM-54 air-to-air missiles
Born in the purple
The F-14 is advanced, with the AN/AWG-9 fire control radar system and the AIM-54 Undead Bird long-range air-to-air missile as two pillars. Both came from an extraordinary source— the famous 3-speed XB-70 strategic bomber and the A-12 strategic reconnaissance aircraft (later Air Force models were called SR-71 Blackbirds). Although the former only ended in trial production, both are the best efforts of the elite of the AMERICAN aviation industry, and the subsystems supporting them are also excellent.
In order to match the XB-70, Hughes (now merged with Raytheon) began developing the ASG-18 pulse Doppler fire control radar and the GAR-9 (later renamed AIM-47 Falcon) long-range air-to-air missile in the 1950s. The rapid development of Soviet strategic bombers in the context of the nuclear war at that time prompted the U.S. Air Force to have a special love for high-altitude high-speed interceptors.
The U.S. Air Force wants them to use missiles exclusively to attack large bombers that are not highly mobile. To this end, North American companies tried to reduce the XB-70 to the XF-108 "Light Sword" interceptor. It was discontinued in September 1959 due to excessive cost. After the initial success of the A-12, Master Johnson of the Skunk factory immediately thought that it could be improved into an anti-aircraft interceptor, and persuaded the Air Force to equip the A-12 with ASG-18 radar and GAR-9 air-to-air missiles to deal with supersonic bombers under Soviet development.
In March 1960, Lockheed began designing the AF-12 interceptor, which was fitted with an ASG-18 radar system and an infrared tracker at the front end to detect low-altitude aircraft at long distances. Four bomb bays are arranged longitudinally on both sides of the belly, each equipped with a AIM-47 with a range of 193 km. The missile can carry both a high-explosive conventional warhead and a low-yield nuclear warhead. The AF-12 first flew on August 7, 1963, and in early 1964 it successfully test-fired the missile with the Mach 3. The production F-12B can be mounted with up to 8 missiles. But in January 1968 it was canceled by Defense Minister McNamara, who was superstitious about strategic missiles.
The F-12 followed the latter's Hughes radar and Falcon missile systems, as well as the A-12's Mach 3 airframe
In the second half of 1960, the U.S. Navy asked Hughes to begin developing the AAM-N-11 missile and the AN/AWG-9 fire control radar on the basis of the AIM-47 and ASG-18. In June 1963, the AAM-N-11 was renamed aim-54A "Undead Bird".
The two systems were originally intended to be equipped with the F-111A, an F-111B naval fighter developed at the same time as the F-111A for long-range interception and fleet air defense, but due to the F-111B's overweight structure and the difficulties encountered by the AWG-9, they were discontinued in 1968. It was not until 1974 that the an/AWG-9 fire control radar and the AIM-54 "Undead Bird" air-to-air missile found a home in the F-14, forming a "golden combination" to undertake the long-range air defense mission of the fleet and protect the aircraft carrier formation from Soviet supersonic bombers.
Now, 30 years later, the duo is still murderous. Even with the rapid development of airborne radar and air-to-air missiles and the imminent replacement of the F-14, there are still few opponents in the world who can compete with this combination in terms of range and multi-target strike capabilities, except for a few long-range models of Russia.
Fire-eyed golden-eyed
The AN/AWG-9 fire control radar system was manufactured by hughes Aircraft Corporation's Radar Systems Division, and by 1988 nearly 800 units had been produced for the Navy and 80 for Iran. The whole machine was discontinued in August 1988, and the spare parts were discontinued in 1989. The system weighs 590 kg and has a volume of 0.79 cubic meters, including 2 power supply components, 3 computer components, 5 signal processors, 4 radar control components, 3 transmitter components, 3 missile auxiliary components, 5 cockpit display components and antennas, with an output power of 10.2 kilowatts, and a light 5400B digital computer.
Depending on the size of the target, the maximum detection range of the AWG-9 pulse Doppler radar is between 120 and 315 kilometers, but its biggest breakthrough is the down-field shooting capability and multi-target tracking/attack capability. It was one of the first radars equipped with a signal processor, which not only enhanced the air-to-air detection capability, but also filtered out ground and sea clutter through analog filtering, so that airborne weapons could strike low-altitude targets, which was also very helpful for detecting and intercepting anti-ship missiles flying across the sea. The minimum height of the detection target reaches 15 meters, and the maximum height is 24384 meters. At maximum distances and widest angles, the radar can scan airspace up to 273 kilometers wide.
The AWG-9's multi-target tracking capabilities are its most commendable features. Using the Side-Track, Side-Scan (TWS) mode, it can track up to 24 targets simultaneously and attack 6 of them at the same time, maintaining its leading position for many years. This capability is aided by advanced time-sharing technology. After the radar detects the target, it does not continuously illuminate each target, but the fire control computer compares the target distance and orientation data obtained by each scan with the results of the last detection at any time. If it matches the predicted position of a saved echo, the location information for that target is updated; If there is no association, it is determined as a new target.
At the same time, this method also allows the radar to guide multiple AIM-54 "undead Bird" missiles flying in the air. For semi-active radar-guided missiles, once the carrier loses its lock on to the target, the missile becomes untargeted. Active radar-guided missiles such as the Undead Bird and the Advanced Medium-Range Air-to-Air Missile (AMRAAM) only need to be updated by the carrier aircraft occasionally to track the target until it enters the range of the missile's own radar seeker. Throughout the process, the missile only intermittently utilizes the radar of the carrier aircraft, allowing the radar to accomplish more tasks.
In addition, the fire control computer will also prioritize targets according to the size of the threat before launching, so as to prioritize the target with the greatest threat, thereby enhancing the survivability of the carrier aircraft in a multi-threat environment.
The AWG-9's radar uses a crack array flat array antenna with a diameter of 914 mm, which is less susceptible to interference and has a higher gain than a parabolic antenna of the same size. It divides the search area into horizontal strips for raster scanning. The wide-range scan mode covers a space 170° wide and takes 13 seconds, while the narrowest scan mode covers a space 10° wide in just 1/4 second. There are also 2 rows of dipoles directly on the antenna for the friend or foe identification system antenna.
The AN/AWG-9 radar antenna has 2 traveling-wave tube transmitters, one that provides continuous-wave target illumination for the semi-active radar seeker of the AIM-7 Sparrow missile (at this time the maximum range of action is 70 km), and the other provides a conventional pulse or pulse Doppler beam, where the pulse modes include pulse search (PS) and pulse single target tracking (PSTT), at which point the maximum detection distances are 117 km and 91 km, respectively.
The pulsed Doppler modality is more complex and includes:
◎ Pulse Doppler search (PDS): used to search for targets, can generate distance change rate and azimuth data, for radar reflection cross-section of 5 square meters of targets, the maximum detection distance of 213 km:
◎ Pulse Doppler Single Target Tracking (PDSTT): Can reliably lock a single long-range target at a distance of 128 kilometers, and can launch missiles at a distance of 100 kilometers. This modal radar can also be cross-linked to the aircraft's optoelectronic sighting device. In addition, in this mode, the interference angle tracking (JAT) device on the radar antenna can be used to measure the distance, speed and orientation information of the enemy aircraft using on-board electronic jamming measures.
◎ Scanning while ranging (RWS): The use of high pulse repetition rate (PF), can generate distance, distance change rate and azimuth data, play a role in finding the target and determining the distance. PRF is the number of pulses emitted by a radar. With a high PRF, the radar can determine the speed of change in the distance of the target, thereby determining the speed at which it is approaching.
◎ Track while scanning (TWS): Used to guide the "Undead Bird" missile for multi-target engagement, at this time the maximum range of the missile is 90 kilometers. Using advanced time-sharing technology, the radar can provide mid-range guidance to six Undead Bird missiles at the same time, allowing them to attack 6 different targets.
The maximum detection distance in both RWS and TWS modes is 167 km. The main difference between the two is that in the RWS mode. Because the trace file has not yet been established, the AWG-9 cannot determine the attack plan, but RWS can scan a larger range of airspace than TWS, scanning at a frequency of 2 seconds.
In addition, the AWG-9 radar has a number of other modes. For example, vertical scan locking (VSL), in which the radar can automatically scan a 40° vertical surface with a beam of 4.8° wide, as low as 15° below the body axis to 25° above, or 15° to 55° above. This mode is mainly used in highly maneuverable engagements, generally at a fairly close distance (about 8 km). During strenuous maneuvers, the F-14 may have an inclination angle of 90* or more, and the opposite aircraft may be in a vertical plane relative to itself, so it will have to scan into the vertical plane.
After finding the target, the radar automatically locks and provides the pilot with an attack plan; Pilot Rapid Positioning (PRL) is actually a line of sight mode that uses a wide 2.3" beam, at which point the beam is essentially fixed, and the pilot artificially changes the attitude of the aircraft to aim until the beam catches the enemy aircraft, and the radar automatically locks. The maximum detection distance of the radar in both modes is 9 kilometers.
In addition to controlling the Undead Bird missile, the AWG-9 can also control the firing of AIM-7 Sparrow, AIM-9 Sidewinder missiles, AIM-120 Advanced Medium-Range Air-to-Air Missiles and M61 Vulcan 20 mm Gatling cannons.
There are pros and cons. Airborne radar has the weakness of easily exposing its own position, so the F-14 early considered passive detection methods, that is, the use of weak signals (such as infrared signals) to detect the receiving target. The F-14A was first fitted with an AN/ALR-23 infrared detection device, which can be cross-linked with radar or can work independently to avoid premature detection by enemy radar alarm receivers. However, the system was not reliable enough, so from the 125th batch of F-14A, it was replaced by the AN/AXX-1 Television Camera System (TCS) developed by Northrop, which was still installed in front of the landing gear compartment under the nose.
The TCS system consists of a camera with an auto-stabilization lens, and the image can be displayed on the screen above the pilot's radar display. While it can't be compared to radar's detection distance, it does provide a useful means of identifying targets beyond the pilot's visual distance. This is especially important in situations where rules of engagement are limited, as it is sometimes required that the source of the target must be confirmed before firing, in which case the TCS may provide a rare fighter. Since then, as infrared technology has matured, the F-14D has re-adopted the infrared search and tracking (IRST) system.
An/AXX-1 television camera system under the F-14 nose
A master of distances
The first long-range air-to-air missiles developed by the United States began in the 1950s with the AAM-N-10 Eagle, which was originally planned to be equipped with the Navy's F6D fighter, but was cancelled in the late 1950s. Later there was the AIM-54A "Undead Bird". Flight tests of the YAIM-54A began in 1965, and the first air-to-air test was successful in September 1966. Its production version began to be delivered to the U.S. Navy in 1973, equipped with the first F-14 squadron in 1974, and by 1980 a total of 2520 pieces had been produced.
The AIM-54A "Undead Bird" is similar to the earlier AIM-47 "Falcon" in a normal aerodynamic layout, with a small outstretched wing in a cross-shaped arrangement than a triangular wing, and a rectangular control wing surface at the tail. The projectile body is in order of guidance module, warhead cabin, engine bay and control cabin from front to back. The warhead module is equipped with the MK11 target detector, the MK334 fuze (trigger fuze or Doppler proximity fuze) and the MK82 continuous pole type high-energy blast warhead. The engine uses the MK47 or MK60 single-stage solid rocket engine, and the jet of the engine is through the control compartment through 4 gas ducts and out of the tail nozzle.
The "Undead Bird" has a supersonic aircraft as its main target, and its own speed is also very amazing. In low-altitude use, the missile speed can reach Mach 3.8 when the rocket is burned, up to Mach 5 at high altitude, and the missile maneuver overload in the test is up to 17g. In order to solve the problem of pneumatic heating, its projectile structure adopts aluminum skin separated by cork and plastic to form a lightweight cooling structure.
During combat, the "Undead Bird" missile is fired by the weapon controller in the rear compartment of the F-14 fighter, and there are three launch modes: scanning and firing while tracking, pulse Doppler single-target tracking launch, and air combat maneuver launch. According to different tactical situations, semi-active radar seeking, active radar seeking and autopilot can be used comprehensively. When performing a maximum range attack, the missile climbs under autopilot control immediately after launch to reduce interference from the AWG-9 radar's powerful transmitter to the missile-guided receiver and to keep the missile in optimal aerodynamic condition.
In the middle of the ballistic trajectory, it is replaced by the radar seeker of the warhead, but is still guided semi-actively. At a distance of 22.5 kilometers from the target, the radar on the bomb enters active guidance, and the flight time can be up to 3 minutes. When the missile is severely jammed and the AWG-9 radar is unable to lock on to its target, there is also a pattern in which most of the range is controlled by autopilot and only the seeker on the missile is turned on at the end.
The F-14's earliest design required the mounting of six "undead birds", four hanging under the belly of the aircraft, and 2 hanging points on the fixed wing covers on both sides. However, it was later found that this had too much impact on the deck when landing on the ship, so it was rarely used. Typical missions typically hang 4 "undead birds", 2 "sparrows" and 2 "side-tailed snakes".
The Undead Bird was first launched from the F-14 on April 28, 1972, and officially entered service on January 28, 1975. Although its performance is superior, it is worth noting that the "Undead Bird" missile has never been used in actual combat, so its superior performance can only be tested from tests. In one test, an "undead bird" hit a target at a distance of 187 kilometers after launch. On November 22, 1973, when an F-14 was flying at an altitude of 7559 meters at a speed of Mach 0.78, it fired six "undead birds" at six target aircraft in 38 seconds, 4 direct hits, 1 failed, and 1 encountered a target aircraft failure.
In other tests, the AWG-9/AIM-54A combination repeatedly hit target aircraft of the MiG-25 fighter's Bomak missile and the simulated Tu-26 Backfire bomber. The ability of the Undead Bird to attack sea-skimming anti-ship missiles and violently maneuvering targets was also demonstrated in tests, and in early 1983, during a joint U.S.-NATO naval exercise in the Caribbean, the AIM-54A launched by F-14A fighter jets intercepted and destroyed 1 Harpoon anti-ship missile.
Blue out of blue
The first improved version of the AIM-54A was the AIM-54B, which featured a liquid-free design to simplify maintenance and changed the wings and tails from honeycomb to flakes, but the performance was not much improved, so it was rejected by the military. The first practical and improved version of the AIM-54A was the AIM-54C. Development began in 1977 with the main purpose of improving combat performance in order to better deal with the air threats of the 90s, such as the Soviet AS-4 "kitchen" and THE-6 "Kingfish" air-to-ground missile.
The biggest feature of the AIM-54C is the use of all-solid-state electronic components, which realize digitalization, while increasing the engine thrust, improving the warhead and fuze, so that its attack distance and altitude, the ability to deal with mobile targets, small targets and low-altitude targets, the ability to resist electronics and the ability to identify interference sources such as foil strips have been enhanced. The new WDU-29/B prefabricated fragmentation warhead was also used in production, and the lethality was increased by 20% to 25%. The AIM-54C began testing in August 1979, was put into production in 1982, and had initial combat capability in 1986, with a total of about 2,550 pieces produced by 1992.
The original intention of improving the "undead bird" was at least out of fear that the Soviet Union might have obtained the AIM-54A originally supplied to Iran. In early 1985, the United States introduced the AIM-54C+, mainly to the C-type guidance system to add a closed refrigeration system, also known as the "closed" missile. This improvement allows for a wider operating temperature range for the missile's digital electronic components, as well as improvements in components such as the guidance module, control cabin, warhead module, signal processor and antenna. The AIM-54C+ was formed in 1988, but the exact number of productions is unknown.
The Undead Bird missiles are expensive, costing more than $1 million each, so there are several coaching types of A and C: the ATM-54A/C without warhead and for firing training; CATM-54A/C, which cannot be launched and is only used for target capture and lock training; Model bomb DATM-54A for ground operation and maintenance training; AEM-54C for electronic testing and evaluation.
By the early 1990s, more than 5,000 Of the various types of Undead Bird missiles had been produced, of which the AIM-54C accounted for about half, the active models were all AIM-54C and AIM-54C+, and the remaining AIM-54A was stockpiled. With the drastic changes in the military situation, the task of protecting the fleet from enemy high-speed bombers when the AIM-54 was originally designed no longer important, and for a considerable period of time to come, intercepting low-altitude high-speed anti-ship missiles has risen to the main task of the "undead bird". But since the AIM-54 missile can only be used for the F-14, its fate can only be closely linked to the Tomcat. By the time the F-14s were fully retired in 2010, the "undead bird" could not be "immortal" after all. At present, the U.S. Navy has no plans to develop similar models.