AD-3W / AD-4W / AD-5W / EA-1E Skyraider radar picketThe first prototype aircraft, designated XAD-1W flew in 1949. It was a three-place unarmed early warning aircraft, with two radar station operators and AN / APS-20 navigation and search radar in a huge fairing under the fuselage. A small series of 30 aircraft produced a version of long-range radar detection AD-3W. Under the fuselage of each of them, a bulky fairing of the rotating AN / APS-20 radar antenna was suspended. The unusual appearance of the aircraft, reminiscent of the famous aquarium fish, was the reason for the playful nickname - "Guppy". The reconnaissance crew consisted of three people: a pilot and two operators of airborne equipment, one of which was observing the air situation, and the other was in constant radio communication with an aircraft carrier or airplanes in the air.
By June 1945 the first group of extensively modified Carrier Airborne Early Warning (AEW) TBM-3W AVENGERS was conducting trials onboard USS RANGER (CV 61). The war ended before the first AEW units could see action2 however, Fleet Aviation Electronics Training Units (FAETU1s) were established on both coasts and continued to train pilots, operators, and maintenance personnel on AEW equipment. VAW-1 on the West Coast and VAW-2 on tpe East Coast were formed to replace
To improve the stability of the machine on its stabilizer fixed small fixed vertical surfaces. Armament was not installed on the AD-3W. Two underwing wings were used to suspend fuel tanks. During the operation of the aircraft, an attempt was made to use the capabilities of an airborne radar in conjunction with a magnetic detector to search for submarines.
Two aircraft underwent modernizations and received the designation AD-3E (factory numbers 122906 and 122907). According to the military plan, these aircraft were to report the coordinates of the located submarines to special destruction aircraft. These two aircraft were created on the basis of night attack aircraft Skyraider, assigning them the designation AD-3S. At the end of the test program, one AD-3S was equipped with an AN / APS-31 radar to investigate the possibility of using one universal aircraft instead of two different modifications.
The AD-4W, the long-range radar (radar) radar equipped with the AN / APS-20A radar, was a modification of the AD-4, its characteristics were greatly improved, compared to the AD-3W radar. Thus, the transmitter power, according to American sources, was reduced to one megawatt. Such a high value seems very doubtful, given that the power of most modern ground-based radars manufactured without significant limitations in size and mass does not exceed several hundred kilowatts.
Vibrations of the bulky fairing and shading of the view by the fuselage and wings greatly reduced the range and quality of detection of air targets. Despite this, the aircraft was widely used in Korea. The AD-3W and AD-4W were constantly "suspended" in the air and warned ships of the approach of enemy aircraft.
Following the Korean War, VC-12 continued to operate an improved verson of the "Guppy Spad", the AD-5W, until 1960 when they were traded for the new WF-2 TRACER (Willy Fudd), later redesignated as the E-1B. The AD-5W (Redesignated EA-1E) was an airborne early warning version. A redesign of the aircraft, the AD-5 incorporated side by side seating for an assistant pilot. The revised crew arrangement facilitated all-weather operation and permitted utilization for long range navigation, radar search, spotting and observation, air support coordination, instrument training, pilot familiarization and other operations requiring a second crew member. Controls, armament and tactical equipment were located for single pilot operation.
The British, who showed great interest to the AD-4W, obtained permission to purchase fifty such aircraft. In English carrier aviation, they received the designation AEW.1. Of these, only 20 aircraft were new, the rest were transferred directly from the combat units of American deck aviation. In the period from 1960 to 1962, the AEW.1 Skyraider was removed from service and replaced with new turboprops AEW.2 "Gannet" (designation AEW.2 carried the basic four-engine plane "Shackleton"). The version of the long-range radar detection AD-5W (239 cars) was also produced. Since 1962 they have become known as EA-1E.
By June 1945 the first group of extensively modified Carrier Airborne Early Warning (AEW) TBM-3W AVENGERS was conducting trials onboard USS RANGER (CV 61). The war ended before the first AEW units could see action2 however, Fleet Aviation Electronics Training Units (FAETU1s) were established on both coasts and continued to train pilots, operators, and maintenance personnel on AEW equipment. VAW-1 on the West Coast and VAW-2 on tpe East Coast were formed to replace
To improve the stability of the machine on its stabilizer fixed small fixed vertical surfaces. Armament was not installed on the AD-3W. Two underwing wings were used to suspend fuel tanks. During the operation of the aircraft, an attempt was made to use the capabilities of an airborne radar in conjunction with a magnetic detector to search for submarines.
Two aircraft underwent modernizations and received the designation AD-3E (factory numbers 122906 and 122907). According to the military plan, these aircraft were to report the coordinates of the located submarines to special destruction aircraft. These two aircraft were created on the basis of night attack aircraft Skyraider, assigning them the designation AD-3S. At the end of the test program, one AD-3S was equipped with an AN / APS-31 radar to investigate the possibility of using one universal aircraft instead of two different modifications.
The AD-4W, the long-range radar (radar) radar equipped with the AN / APS-20A radar, was a modification of the AD-4, its characteristics were greatly improved, compared to the AD-3W radar. Thus, the transmitter power, according to American sources, was reduced to one megawatt. Such a high value seems very doubtful, given that the power of most modern ground-based radars manufactured without significant limitations in size and mass does not exceed several hundred kilowatts.
Vibrations of the bulky fairing and shading of the view by the fuselage and wings greatly reduced the range and quality of detection of air targets. Despite this, the aircraft was widely used in Korea. The AD-3W and AD-4W were constantly "suspended" in the air and warned ships of the approach of enemy aircraft.
Following the Korean War, VC-12 continued to operate an improved verson of the "Guppy Spad", the AD-5W, until 1960 when they were traded for the new WF-2 TRACER (Willy Fudd), later redesignated as the E-1B. The AD-5W (Redesignated EA-1E) was an airborne early warning version. A redesign of the aircraft, the AD-5 incorporated side by side seating for an assistant pilot. The revised crew arrangement facilitated all-weather operation and permitted utilization for long range navigation, radar search, spotting and observation, air support coordination, instrument training, pilot familiarization and other operations requiring a second crew member. Controls, armament and tactical equipment were located for single pilot operation.
The British, who showed great interest to the AD-4W, obtained permission to purchase fifty such aircraft. In English carrier aviation, they received the designation AEW.1. Of these, only 20 aircraft were new, the rest were transferred directly from the combat units of American deck aviation. In the period from 1960 to 1962, the AEW.1 Skyraider was removed from service and replaced with new turboprops AEW.2 "Gannet" (designation AEW.2 carried the basic four-engine plane "Shackleton"). The version of the long-range radar detection AD-5W (239 cars) was also produced. Since 1962 they have become known as EA-1E.
RADIATION LABORATORY AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY
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Title:Radiation Laboratory at the Massachusetts Institute of Technology
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Ernest Lawrence's laboratory at University of California Berkeley, now known as http://www.eecs.umich.edu/RADLAB).The Radiation Laboratory, commonly called the Rad Lab, was located at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts and functioned from October 1940 until December 31, 1945. Alfred Lee Loomis, a millionaire and physicist who headed his own private laboratory, selected the location for the laboratory on the campus, named it the MIT Radiation Laboratory, and arranged funding for the Rad Lab until federal money was allocated. It was formed by, and initially operated under, the National Defense Research Committee (NDRC), a commission established by U. S. President Franklin D. Roosevelt with Vannevar Bush as its chairman. In 1941, the NDRC was enlarged to become the Office of Scientific Research and Development (OSRD), with Bush remaining as chairman. Lee A. DuBridge served as the Rad Lab director. This facility was responsible for developing most of the microwave radars used by the United States during World War II,[1] including the H2X radar used for bomb-aiming and the subsequent improvements to the initial H2X radar's technology.
The Rad Lab also developed LORAN, the first worldwide radio navigation system, which originally was known as "LRN" for Loomis Radio Navigation, after Alfred Lee Loomis, who invented LORAN and played a crucial role in military research and development during WWII. It remained the most widely used long-range navigation system until the advent of GPS, which was developed from it and became used by the public after 2000.
The Rad Lab also developed LORAN, the first worldwide radio navigation system, which originally was known as "LRN" for Loomis Radio Navigation, after Alfred Lee Loomis, who invented LORAN and played a crucial role in military research and development during WWII. It remained the most widely used long-range navigation system until the advent of GPS, which was developed from it and became used by the public after 2000.
FORMATION
During the mid- and late-1930s, radio systems for the detection and location of distant targets had been developed under great secrecy in the United Statesand Great Britain, as well as in several other nations, notably Germany, the USSR, and Japan. These usually operated at Very High Frequency (VHF) wavelengths in the electromagnetic spectrum and carried several cover names, such as Ranging and Direction Finding (RDF) in Great Britain. In 1941, the U. S. Navy coined the acronym RADAR (RAdio Detection And Ranging) for such systems; this soon led to the name radar and spread to other countries.
The potential advantages of operating such systems in the Ultra High Frequency (UHF or microwave) region were well known and vigorously pursued. One of these advantages was smaller antennas, a critical need for detection systems on aircraft. The primary technical barrier to developing UHF systems was the lack of a usable source for generating high-power microwaves. In February 1940, researchers John Randall and Harry Boot at Birmingham University in Great Britain built a resonant cavity magnetron to fill this need; it quickly was placed in the highest level of secrecy.
Shortly after this breakthrough, Britain's Prime Minister Winston Churchill and President Roosevelt agreed that the two nations would pool their technical secrets and jointly develop many urgently needed warfare technologies. At the initiation of this exchange in the late summer of 1940, the Tizard Missionbrought to America one of the first of the new magnetrons. On October 6, Edward George Bowen, a key developer of RDF at the Telecommunications Research Establishment (TRE) and a member of the mission, demonstrated this magnetron, producing some 15,000 watts (15 kW) of power at 10-cm wavelength. (Microwave components usually are designated in wavelength, rather than frequency.)
American researchers and officials were amazed at the magnetron, and the NDRC immediately started plans for manufacturing and incorporating these devices. Alfred Lee Loomis, who headed the NDRC Microwave Committee, led in establishing the Radiation Laboratory at MIT as a joint Anglo-American effort for microwave research and developing systems using the new magnetron.
The name Radiation Laboratory, selected by Loomis when he selected the building for it on the MIT campus, intentionally was deceptive,[3] albeit obliquely correct in that radar uses radiation in a portion of the electromagnetic spectrum. It was chosen to imply that the laboratory's mission was similar to that of the Ernest O. Lawrence's Radiation Laboratory at UC Berkeley; i.e., that it employed scientists to work on nuclear physics research. At the time, nuclear physics was regarded as relatively theoretical and inapplicable to military equipment, as this was before atomic bombdevelopment had begun.
Ernest Lawrence was an active participant in forming the Rad Lab and personally recruited many key members of the initial staff. Most of the senior staff were Ph.D. physicists who came from university positions. They usually had no more than an academic knowledge of microwaves, and almost no background involving electronic hardware development. Their capability, however, to attack complex problems of almost any type was outstanding. Later in life, nine members of the staff were recipients of the Nobel Prize for their other accomplishments.
In June 1941, the NDRC became part of the new Office of Scientific Research and Development (OSRD), also administered by Vannevar Bush, who reported directly to President Roosevelt. The OSRD was given almost unlimited access to funding and resources, with the Rad Lab receiving a large share for radar research and development.
Starting in 1942, the Manhattan Project absorbed a number of the Rad Lab physicists into Los Alamos and Lawrence's facility at Berkeley. This was made simpler by Lawrence and Loomis being involved in all of these projects.[4]
During the mid- and late-1930s, radio systems for the detection and location of distant targets had been developed under great secrecy in the United Statesand Great Britain, as well as in several other nations, notably Germany, the USSR, and Japan. These usually operated at Very High Frequency (VHF) wavelengths in the electromagnetic spectrum and carried several cover names, such as Ranging and Direction Finding (RDF) in Great Britain. In 1941, the U. S. Navy coined the acronym RADAR (RAdio Detection And Ranging) for such systems; this soon led to the name radar and spread to other countries.
The potential advantages of operating such systems in the Ultra High Frequency (UHF or microwave) region were well known and vigorously pursued. One of these advantages was smaller antennas, a critical need for detection systems on aircraft. The primary technical barrier to developing UHF systems was the lack of a usable source for generating high-power microwaves. In February 1940, researchers John Randall and Harry Boot at Birmingham University in Great Britain built a resonant cavity magnetron to fill this need; it quickly was placed in the highest level of secrecy.
Shortly after this breakthrough, Britain's Prime Minister Winston Churchill and President Roosevelt agreed that the two nations would pool their technical secrets and jointly develop many urgently needed warfare technologies. At the initiation of this exchange in the late summer of 1940, the Tizard Missionbrought to America one of the first of the new magnetrons. On October 6, Edward George Bowen, a key developer of RDF at the Telecommunications Research Establishment (TRE) and a member of the mission, demonstrated this magnetron, producing some 15,000 watts (15 kW) of power at 10-cm wavelength. (Microwave components usually are designated in wavelength, rather than frequency.)
American researchers and officials were amazed at the magnetron, and the NDRC immediately started plans for manufacturing and incorporating these devices. Alfred Lee Loomis, who headed the NDRC Microwave Committee, led in establishing the Radiation Laboratory at MIT as a joint Anglo-American effort for microwave research and developing systems using the new magnetron.
The name Radiation Laboratory, selected by Loomis when he selected the building for it on the MIT campus, intentionally was deceptive,[3] albeit obliquely correct in that radar uses radiation in a portion of the electromagnetic spectrum. It was chosen to imply that the laboratory's mission was similar to that of the Ernest O. Lawrence's Radiation Laboratory at UC Berkeley; i.e., that it employed scientists to work on nuclear physics research. At the time, nuclear physics was regarded as relatively theoretical and inapplicable to military equipment, as this was before atomic bombdevelopment had begun.
Ernest Lawrence was an active participant in forming the Rad Lab and personally recruited many key members of the initial staff. Most of the senior staff were Ph.D. physicists who came from university positions. They usually had no more than an academic knowledge of microwaves, and almost no background involving electronic hardware development. Their capability, however, to attack complex problems of almost any type was outstanding. Later in life, nine members of the staff were recipients of the Nobel Prize for their other accomplishments.
In June 1941, the NDRC became part of the new Office of Scientific Research and Development (OSRD), also administered by Vannevar Bush, who reported directly to President Roosevelt. The OSRD was given almost unlimited access to funding and resources, with the Rad Lab receiving a large share for radar research and development.
Starting in 1942, the Manhattan Project absorbed a number of the Rad Lab physicists into Los Alamos and Lawrence's facility at Berkeley. This was made simpler by Lawrence and Loomis being involved in all of these projects.[4]
OPERATIONS
The Radiation Laboratory officially opened in November 1940, using 4,000 square feet (370 m2) of space in MIT's Building 4, and under $500,000 initial funding from the NDRC. In addition to the Director, Lee DuBridge, I. I. Rabi was the deputy director for scientific matters and F. Wheeler Loomis (no relation to Alfred Loomis) the deputy director for administration. E. G. ("Taffy") Bowen was assigned as a representative of Great Britain.
Even before opening, the founders identified the first three projects for the Rad Lab. In the order of priority, these were (1) a 10-cm detection system (called Airborne Intercept or AI) for fighter aircraft, (2) a 10-cm gun-aiming system (called Gun Laying or GL) for anti-aircraft batteries, and (3) a long-range airborne radio navigation system.
To initiate the first two of these projects, the magnetron from Great Britain was used to build a 10-cm "breadboard" set; this was tested successfully from the rooftop of Building 4 in early January 1941. All members of the initial staff were involved in this endeavor.
Under Project 1 led by Edwin M. McMillan, an "engineered" set with an antenna using a 30-inch parabolic reflector followed. This, the first microwave radar built in America, was tested successfully in an aircraft on March 27, 1941. It was then taken to Great Britain by Taffy Bowen and tested in comparison with a 10-cm set being developed there. For the final system, the Rad Lab staff combined features from their own and the British set. It eventually became the SCR-720, used extensively by both the U.S. Army Air Corps and the British Royal Air Force.
For Project 2, a 4-foot (later 6-foot) parabolic reflector on a pivoting mount was selected. Also, this set would use an electro-mechanical computer (called a Predictor-correlator) to keep the antenna aimed at an acquired target. Ivan A. Getting served as the project leader. Being much more complicated than the AI and required to be very rugged for field use, an engineered GL was not completed until December 1941. This eventually was fielded as the ubiquitous SCR-584, first gaining attention by directing the anti-aircraft fire that downed the about 85 percent of German V-1 flying bombs ("buzz bombs") attacking London.[5]
Project 3, a long-range navigation system, was of particular interest to Great Britain. They had an existing hyperbolic navigation system, called GEE, but it was inadequate, in both range and accuracy, to support aircraft during bombing runs on distant targets in Europe. When briefed by the Tizard Mission about GEE, Alfred Loomis personally conceptualized a new type of system that would overcome the deficiencies of GEE, and the development of his LORAN (an acronym for Long Range Navigation) was adopted as an initial project. The LORAN Division was established for the project and headed by Donald G. Fink. Operating in the Low Frequency (LF) portion of the radio spectrum, LORAN was the only non-microwave project of the Rad Lab. Incorporating major elements of GEE, LORAN was highly successful and beneficial to the war effort. By the end of hostilities, about 30 percent of the Earth's surface was covered by LORAN stations and used by 75,000 aircraft and surface vessels.[6]
Following the Japanese Attack on Pearl Harbor and the entry of the U. S. into World War II, work at the Rad Lab greatly expanded. At the height of its activities, the Rad Lab employed nearly 4,000 people working in several countries. The Rad Lab had constructed, and was the initial occupant of, MIT's famous Building 20. Costing just over $1 million, this was one of the longest-surviving World War II temporary structures.
Activities eventually encompassed physical electronics, electromagnetic properties of matter, microwave physics, and microwave communication principles, and the Rad Lab made fundamental advances in all of these fields. Half of the radars deployed by the U. S. military during World War II were designed at the Rad Lab, including over 100 different microwave systems costing $1.5 billion.[7] All of these sets improved considerably on pre-microwave, VHF systems from the Naval Research Laboratory and the Army's Signal Corps Laboratories, as well as British radars such as Robert Watson-Watt's Chain Home and Taffy Bowen's early airborne RDF sets.
Although the Rad Lab was initiated as a joint Anglo-American operation and many of its products were adopted by the British military, researchers in Great Britain continued with the development of microwave radar and, particularly with cooperation from Canada, produced many types of new systems. For the exchange of information, the Rad Lab established a branch operation in England and a number of British scientists and engineers worked on assignments at the Rad Lab.
The resonant-cavity magnetron continued to evolve at the Rad Lab. A team led by I. I. Rabi first extended the operation of the magnetron from 10-cm (called S-band), to 6-cm (C-band), then to 3-cm (X-band), and eventually to 1-cm (K-band). To keep pace, all of the other radar sub-systems also were evolving continuously. The Transmitter Division, under Albert G. Hill, eventually involved a staff of 800 persons in these efforts.
A radically different type of antenna for X-band systems was invented by Luis W. Alvarez and used in three new systems: an airborne mapping radar called Eagle, a blind-landing Ground Control Approach (GCA) system, and a ground-based Microwave Early-Warning (MEW) system. The latter two were highly successful and carried over into post-war applications. Eagle eventually was converted to a very effective mapping radar called H2X or Mickey and used by the U. S. Air Corps and Navy as well as the British RAF.[8]
The most ambitious Rad Lab effort with long-term significance was Project Cadillac. Led by Jerome B. Wiesner, the project involved a high-power radar carried in a pod under a TBM Avenger aircraft and a Combat Information Center aboard an aircraft carrier. The objective was an airborne early warning and control system, providing the U. S. Navy with a surveillance capability to detect low-flying enemy aircraft at a range in excess of 100 miles (161 km). The project was initiated at a low level in mid-1942, but with the later advent of Japanese Kamikaze threats in the Pacific Theater of Operations, the work was greatly accelerated, eventually involving 20 percent of the Rad Lab staff. A prototype was flown in August 1944, and the system became operational early the next year. Although too late to affect the final war effort, the project laid the foundation for significant developments in the following years.[9]
As the Rad Lab started, a laboratory was set up to develop electronic countermeasures (ECM), technologies to block enemy radars and communications. With Frederick E. Terman as director, this soon moved to the Harvard University campus (just a mile from MIT) and became the Radio Research Laboratory (RRL). Organizationally separate from the Rad Lab, but also under the OSRD, the two operations had much in common throughout their existences.
CLOSURE
When the Radiation Laboratory closed, the OSRD agreed to continue funding for the Basic Research Division, which officially became part of MIT on July 1, 1946, as the Research Laboratory of Electronics at MIT (RLE). Other wartime research was taken up by the MIT Laboratory for Nuclear Science, which was founded at the same time. Both laboratories principally occupied Building 20 until 1957.
Most of the important research results of the Rad Lab were documented in a 28-volume compilation entitled the MIT Radiation Laboratory Series, edited by Louis N. Ridenour and published by McGraw-Hill between 1947 and 1953. This is no longer in print, but the series was re-released as a two-Artech House. More recently, it has become available online.
Postwar declassification of the work at the MIT Rad Lab made available, via the Series, a quite-large body of knowledge about advanced electronics. A reference (identity long forgotten) credited the Series with the development of the post-World War II electronics industry.
With the cryptology and cryptographic efforts centered at Bletchley Park and Arlington Hall and the Manhattan Project, the development of microwave radar at the Radiation Laboratory represents one of the most significant, secret, and outstandingly successful technological efforts spawned by the Anglo-American relations in World War II. The Radiation Laboratory was named an IEEE Milestone in 1990.[10]
When the Radiation Laboratory closed, the OSRD agreed to continue funding for the Basic Research Division, which officially became part of MIT on July 1, 1946, as the Research Laboratory of Electronics at MIT (RLE). Other wartime research was taken up by the MIT Laboratory for Nuclear Science, which was founded at the same time. Both laboratories principally occupied Building 20 until 1957.
Most of the important research results of the Rad Lab were documented in a 28-volume compilation entitled the MIT Radiation Laboratory Series, edited by Louis N. Ridenour and published by McGraw-Hill between 1947 and 1953. This is no longer in print, but the series was re-released as a two-Artech House. More recently, it has become available online.
Postwar declassification of the work at the MIT Rad Lab made available, via the Series, a quite-large body of knowledge about advanced electronics. A reference (identity long forgotten) credited the Series with the development of the post-World War II electronics industry.
With the cryptology and cryptographic efforts centered at Bletchley Park and Arlington Hall and the Manhattan Project, the development of microwave radar at the Radiation Laboratory represents one of the most significant, secret, and outstandingly successful technological efforts spawned by the Anglo-American relations in World War II. The Radiation Laboratory was named an IEEE Milestone in 1990.[10]
The requirement for Airborne Early Warning was born shortly after the Battle of Midway. The navigator, Frank Akers of the USS HORNET, one of the participating aircraft carriers, was ordered to the Bureau of Aeronautics as Director of Electronics. In Washington, the Office of Scientific Research and Development established by a directive from the President. It was their practice at this early period of the war to quiz newly arriving officers from the battle area that had certain expertise. Akers promptly found himself before an august group, and one of the first questions asked of him was "What does the Navy need most right now?" His answer came easy and without hesitation, he replied "Surface Search Radar out to two hundred miles." At the Battle of Midway, US forces had been able to detect the Japanese fleet first, resulting in four Japanese aircraft carriers sunk, but difficulties in tracking the adversary fleet kept many US aircraft from engaging the Japanese carriers. In his honor, the AEW Excellence Award was renamed the "Rear Admiral Frank Akers Award.
US Navy Airborne Early Warning Training Unit Number Four
August 1944
Eastern TBM-3W AvengerTBM-3W
The Eastern TBM-3W Avenger was an airborne early warning radar aircraft developed during the Second World War but that only entered service in May 1946. Work on airborne warning radar began early in 1942 at the Radiation Lab at MIT (Project Cadillac). At this point radar was becoming common on warships, but a radar set mounted on a 50ft mast could only detect low flying aircraft at very close range - 20 miles for an aircraft at 500ft. For an aircraft flying at 300mph this only amounted to a four minute warning.
Although the Avenger had not yet entered service it was the obvious aircraft to carry the new radar set, being one of the largest aircraft then operating from carriers, and with a large internal bomb bay. The resulting APS-20 radar set had an 8ft by 3ft antenna, the largest that would fit between the undercarriage legs of the Avenger. The radar set was mounted in the forward part of the bomb bay, with the antenna protected by a massive fibreglass radome. Two radar operators were located in the radio operator's station at the rear of the aircraft, while the turret was removed and a new single place cockpit with a turtle-back fairing replaced the greenhouse. At the same time as gaining a second crewman the radio operator's compartment lost some space as the 'tunnel' was smoothed off to improve the aircraft's rear ground clearance.
The rest of the fuselage was filled with electrical equipment, including two VHF radios, IFF gear, the rest of the radar set and data link relay equipment that could transmit the radar data to another aircraft or to the ground. Finally auxiliary tail fins were added near the tips of the horizontal stabilisers to improve lateral stability.
The XTBM-3W prototype made its maiden flight on 5 August 1944, and was successful enough to encourage the Navy to order a number of conversions. The urgency of this programme dramatically increased after the start of large scale kamikaze attacks, and forty radar sets were produced. Air crews were training with the new aircraft early in 1945, but this training period lasted so long that the war ended before they could join the fleet.
The TBM-3W joined the fleet in May 1946, and was soon paired with the TBM-3S in hunter-killer anti-submarine teams. The powerful radar in the -3W would be used to find a potential Soviet submarine, guiding the -3S onto its target. The -3W remained in service with the US fleet until the mid 1950, when it was replaced by early warning versions of the Grumman AF Guardian and Douglas AD Skyraider.
Although the Avenger had not yet entered service it was the obvious aircraft to carry the new radar set, being one of the largest aircraft then operating from carriers, and with a large internal bomb bay. The resulting APS-20 radar set had an 8ft by 3ft antenna, the largest that would fit between the undercarriage legs of the Avenger. The radar set was mounted in the forward part of the bomb bay, with the antenna protected by a massive fibreglass radome. Two radar operators were located in the radio operator's station at the rear of the aircraft, while the turret was removed and a new single place cockpit with a turtle-back fairing replaced the greenhouse. At the same time as gaining a second crewman the radio operator's compartment lost some space as the 'tunnel' was smoothed off to improve the aircraft's rear ground clearance.
The rest of the fuselage was filled with electrical equipment, including two VHF radios, IFF gear, the rest of the radar set and data link relay equipment that could transmit the radar data to another aircraft or to the ground. Finally auxiliary tail fins were added near the tips of the horizontal stabilisers to improve lateral stability.
The XTBM-3W prototype made its maiden flight on 5 August 1944, and was successful enough to encourage the Navy to order a number of conversions. The urgency of this programme dramatically increased after the start of large scale kamikaze attacks, and forty radar sets were produced. Air crews were training with the new aircraft early in 1945, but this training period lasted so long that the war ended before they could join the fleet.
The TBM-3W joined the fleet in May 1946, and was soon paired with the TBM-3S in hunter-killer anti-submarine teams. The powerful radar in the -3W would be used to find a potential Soviet submarine, guiding the -3S onto its target. The -3W remained in service with the US fleet until the mid 1950, when it was replaced by early warning versions of the Grumman AF Guardian and Douglas AD Skyraider.