The AN/AWG-9 and AN/APG-71 radars are all-weather, multi-mode

X band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is set at approximately 7.0–11.2&nbs ...

pulse-Doppler radar A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and ...

systems used in the

F-14 Tomcat The Grumman F-14 Tomcat is an American carrier-capable supersonic, twin-engine, tandem two-seat, twin-tail, all-weather-capable variable-sweep wing fighter aircraft. The Tomcat was developed for the United States Navy's Naval Fighter Experi ...

, and also tested on TA-3B. It is a long-range air-to-air system capable of guiding several AIM-54 Phoenix or

AIM-120 AMRAAM The AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM) ( ) is an American Beyond-visual-range missile, beyond-visual-range air-to-air missile capable of all-weather day-and-night operations. It uses active transmit-receive radar guidance ...

missiles simultaneously, using its

track while scan Track-while-scan (TWS) is a mode of radar operation in which the radar allocates part of its power to tracking a target or targets (up to forty with modern radar) while part of its power is allocated to scanning. It is similar to but functions diff ...

mode. The AWG-9 utilizes an

analog computer An analog computer or analogue computer is a type of computation machine (computer) that uses physical phenomena such as Electrical network, electrical, Mechanics, mechanical, or Hydraulics, hydraulic quantities behaving according to the math ...

while the APG-71 is an upgraded variant utilizing a

digital computer A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', wh ...

. Both the AWG-9 and APG-71 were designed and manufactured by

Hughes Aircraft Company The Hughes Aircraft Company was a major American aerospace and defense contractor founded on February 14, 1934 by Howard Hughes in Glendale, California, as a division of the Hughes Tool Company. The company produced the Hughes H-4 Hercules air ...

's Radar Systems Group in

Los Angeles Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...

; contractor support was later assumed by

Raytheon Raytheon is a business unit of RTX Corporation and is a major U.S. defense contractor and industrial corporation with manufacturing concentrations in weapons and military and commercial electronics. Founded in 1922, it merged in 2020 with Unite ...

. The AWG-9 was originally created for the canceled Navy F-111B program.Sweetman 1987, p. 622. The AN/AWG-9 offers multiple air-to-air modes: long-range

continuous-wave radar Continuous-wave radar (CW radar) is a type of radar system where a known stable frequency continuous wave radio energy is transmitted and then received from any reflecting objects. Individual objects can be detected using the Doppler effect, which ...

velocity search, range-while-search at shorter ranges, and an airborne track-while-scan mode with the ability to track up to 24 airborne targets, display 18 of them on the cockpit displays, and launch against 6 of them at the same time. This function was originally designed to allow the Tomcat to shoot down formations of bombers at long range.

AN/AWG-9

The AWG-9 was the result of a series of

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

programs to build what was known as a "fleet-defense fighter": an aircraft armed with extremely long-range radars and missiles that would be able to engage formations of enemy aircraft well-away from

aircraft carrier An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and hangar facilities for supporting, arming, deploying and recovering carrier-based aircraft, shipborne aircraft. Typically it is the ...

s. Their first attempt was the F6D Missileer, which combined Westinghouse's AN/APQ-81 pulse doppler radar with the Bendix AAM-N-10 Eagle missile. The Missileer was a relatively simple aircraft, and when planners expressed doubts about its ability to survive after firing its missiles, the Missileer was canceled and the Navy started looking for higher-performance alternatives. At the same time, the

U.S. Air Force The United States Air Force (USAF) is the air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its origins to 1 ...

had been working on a similar long-range interceptor project of their own, the

XF-108 Rapier The North American XF-108 Rapier was a proposed long-range, high-speed interceptor aircraft designed by North American Aviation intended to defend the United States from supersonic Soviet strategic bombers. The aircraft would have cruised at s ...

. The Rapier had much better performance than the Missileer, although its AIM-47 Falcon and AN/ASG-18 radar, both from Hughes, were somewhat less advanced than their Navy counterparts. The entire system was also very expensive, and the Rapier was canceled, replaced by the hopefully less-expensive

Lockheed YF-12 The Lockheed YF-12 is an American Mach number, Mach 3+ capable, high-altitude interceptor aircraft, interceptor prototype, developed and manufactured by American aerospace company Lockheed Corporation. The interceptor was developed duri ...

adapted from the Lockheed A-12 spy plane. This project was also canceled as the strategic threat moved from bombers to

ICBM An intercontinental ballistic missile (ICBM) is a ballistic missile with a range (aeronautics), range greater than , primarily designed for nuclear weapons delivery (delivering one or more Thermonuclear weapon, thermonuclear warheads). Conven ...

s. The same was not true for the Navy, where the threat remained manned aircraft and early

anti-ship missile An anti-ship missile (AShM or ASM) is a guided missile that is designed for use against ships and large boats. Most anti-ship missiles are of the sea-skimming variety, and many use a combination of inertial guidance and active radar homing. ...

s. Hughes suggested that the AN/ASG-18 and AIM-47 could be adapted for the Navy in slightly modified form, adding additional tracking capability while reducing the size of the radar antenna to a size more suitable for carrier aircraft. The result was the AN/AWG-9 radar and Phoenix missile. All that was needed was a suitable airframe, which led to the Navy's involvement in the F-111B program. Although the radar and missile systems started to mature (after the better part of a decade at this point) the F-111B proved to be considerably overweight and had marginal performance, especially in engine-out situations. At the same time, real-world combat over

Vietnam Vietnam, officially the Socialist Republic of Vietnam (SRV), is a country at the eastern edge of mainland Southeast Asia, with an area of about and a population of over 100 million, making it the world's List of countries and depende ...

was proving that the idea of the all-missile fighter was simply not viable, and any fighter design would have to be able to

dogfight A dogfight, or dog fight, is an air combat manoeuvring, aerial battle between fighter aircraft that is conducted at close range. Modern terminology for air-to-air combat is air combat manoeuvring (ACM), which refers to tactical situations requir ...

with guns, which the F-111 was simply not suited to. This should not be surprising given the F-111's genesis as a tactical bomber and

interdictor An interdictor is a type of attack aircraft or tactical bomber that operates far behind enemy lines, with the express intent of air interdiction of the enemy's military targets, most notably those involved in logistics. Interdiction Inter ...

. After many years in development and arguing with Congress, the Navy finally started development of a new aircraft specifically tailored to their needs. The new aircraft emerged as the F-14, armed with the same AWG-9/AIM-54 outfit originally intended for the F-111B. On the F-14, the AWG-9 is capable, and its doppler system allows it to have look-down, shoot-down capabilities.Modern Marvels: F-14 History Channel DVD Hughes delivered enough AWG-9 systems and spares to equip approximately 600 F-14A/B aircraft for the Navy, and an additional 80 aircraft for the Iranian Air Force. All of the Navy systems have been retired; some of Iranian systems are still in service.

AN/APG-71

The APG-71 was a 1980s upgrade of the AWG-9 for use on the F-14D Tomcat. It incorporates technology and common modules developed for the APG-70 radar used in the

F-15E Strike Eagle The McDonnell Douglas (now Boeing) F-15E Strike Eagle is an American all-weather multirole strike fighter derived from the McDonnell Douglas F-15 Eagle. Intended for the Dual-Role Fighter (DRF) program (initially called Enhanced Tactical Fi ...

, providing significant improvements in (digital) processing speed, mode flexibility, clutter rejection, and detection range. The system features a low-sidelobe antenna, a sidelobe-blanking guard channel, and monopulse angle tracking; all of which are intended to make the radar less vulnerable to jamming. The system itself is capable of a range, but the antenna design limits this to only . Use of datalinked radar data allows two or more F-14Ds to operate the system at its maximum range. Hughes delivered enough APG-71 radars and spares to equip all 55 F-14Ds produced or converted before the F-14D program was scaled back as a cost-cutting measure and eventually canceled. The F-14 was officially retired from United States Navy service on September 22, 2006, with the last flight occurring October 4, 2006.

References

Citation

Bibliography

* Sweetman, Bill and Bonds, Ray. ''The Great Book of Modern Warplanes''. New York, New York: Crown Publishers, 1987.

External links