Soon after the appearance of radars, the question arose about increasing the detection range of air targets. This problem was solved in several ways. As far as possible, they tried to place radar stations at dominant heights, which made it possible not only to increase the viewing area, but also to avoid shading from objects on the ground. For the same purpose, the receiving and transmitting antennas of the radar were installed on towers and even tried to be raised on balloons. With an increase in the elevation of the antennas, the detection range could increase by 30-40%, at the same time, the first radars, as a rule, were not able to fix air targets against the background of the earth's surface.
The idea of installing a radar on an aircraft first appeared in the UK in the late 1930s. After the start of massive night raids by German bombers in England, production of twin-engine night fighters Blenheim IF with AI Mk III radar began. The radar-equipped Blenheim heavy fighters performed very well during night interceptions and were later replaced by the more advanced Beaufighter and Mosquito with AI Mk. IV radars. However, night fighters were not radar patrol aircraft in the modern sense, the radar on board was usually used to individually search for an air target and the exchange of information with other interceptors and ground control points was not carried out.
The first ever prototype of the AWACS aircraft was the experimental Vickers Wellington IC, on which a rotating radar antenna was placed above the fuselage, and the equipment was in place of the bomb bay.
Experimental aircraft of the Vickers Wellington IC radar patrol
The construction of this machine on the basis of the Wellington twin-engined bomber was initiated after German single bombers attacked England, bypassing ground-based radars deployed on the east coast of the British Isles. However, after the massive deliveries of the SCR-584 and GL Mk. III, the idea of a radar control aircraft with a rotating radar antenna was abandoned. At the same time, Wellingtons, equipped with radars with fixed antennas, were mass produced. These bombers were successfully used against German submarines that surfaced at night to recharge their batteries. At the end of 1944, there were cases when specially converted Wellingtons with fixed antennas were used to aim Mosquito interceptors at German Heinkel-111 bombers - carriers of V-1 "flying bombs". That was the first combat use of the "air radar picket - interceptor" link in history.
USA
By the mid-40s of the last century, the level of miniaturization and performance of radars reached such a level that it became possible to deploy surveillance radars with a detection range of more than 100 km not only on large two and four-engine aircraft, but also on relatively small single-engine machines.
The Americans were the first to start serial construction of AWACS aircraft. After the outbreak of hostilities in the Pacific, the US Navy needed to move the radar control zone away from its bases and ships in order to obtain a reserve of time necessary to lift a sufficient number of cover fighters into the air. In addition, the aircraft of the radar patrol could control the actions of their own aviation at a distance from the aircraft carrier.
In August 1944, in the battles for Okinawa, the American fleet underwent intense kamikaze attacks, and American admirals urgently placed an order for deck-based AWACS TVM-3W aircraft. This vehicle was created on the basis of the TBM-3 Avenger carrier-based torpedo bomber. Without waiting for the end of the tests, the fleet ordered 40 aircraft with the start of deliveries in March 1945.
Deck aircraft AWACS TVM-3W
For the first time, the "flying radar" TVM-3W took off in August 1944, which coincided with the official conclusion of the order for it. A radome with an AN / APS-20 radar antenna, which was created as part of the Cadillac project, was installed on the aircraft under the middle part of the fuselage. Looking ahead, I will say that modernized versions of this station, which operated in the range of 1-3 meters, were used in the United States and NATO until the end of the 70s, that is, for more than 30 years. The first modification of the AN / APS-20 had very good characteristics for its time, the station, in the absence of interference, could see a bomber-type target at a distance of 120 km.
Externally, the TVM-3W was very different from the torpedo bomber. In addition to the drop-shaped radome fairing, in order to maintain directional stability, additional vertical surfaces had to be installed on the stabilizers - the tail unit became three-keeled. The landing of the TVM-3W demanded special attention, since the clearance was small due to the hanging "belly".
The crew consisted of two people - a pilot and a radar operator. For the most part, the vehicles of the first order were not built anew, but were converted from torpedo bombers. In the role of a platform for the aircraft, the AWACS "Avenger" was not ideal. The small internal volume of the fuselage made it possible to accommodate only one radar operator, and in very cramped conditions.
Although everything went very well for the first American carrier-based AWACS aircraft, its fine-tuning was delayed. After the problems with the unreliable operation of the avionics were resolved, it took time for the development of production vehicles by the flight and technical personnel. As a result, the TVM-3W did not have time to go to war and began to enter combat radar squadrons at the beginning of 1946. The first option was followed by a modification of the TBM-3W2 with an improved radar, which could also work on surface targets and even detect submarine periscopes.
When designing the TBM-3W2, it was assumed that the aircraft would be three-seater, an additional radar operator was added to the crew, who also was in charge of communication equipment and transmitted data on detected air targets. But due to the lack of free space on board, as a rule, the third crew member was not taken on the flight.
In 1953, the US Navy had 156 TBM-3W / W2 aircraft, by that time they were used not only to monitor the air situation, but also to search for submarines together with TBM-3S anti-submarine aircraft. But after a few years, in connection with the arrival of more advanced machines, the decommissioning of the radar "Avengers" began. In addition to the United States, TBM-3W2 aircraft were in service in Canada, the Netherlands and the Japanese Maritime Self-Defense Forces. Moreover, everywhere they were used exclusively as patrol vehicles to control the sea area.
By the end of the 40s, the Avenger, which had been produced since 1941, had become quite obsolete, and the Navy needed a new platform for a carrier-based radar patrol aircraft. In 1949, an aircraft built on the basis of the AD-1 Skyraider carrier-based attack aircraft entered testing.
The first radar version of "Skyrader" with a rotating antenna radar AN / APS-20 in a bulky fairing under the fuselage received the designation AD-3W. This machine was built in a small series of 30 copies and was used mainly for testing and fine-tuning equipment. Because of the characteristic outlines, the sharp-tongued sailors quickly glued the playful nickname "Guppy" to the plane. Just like on the TBM-3, additional washers were installed on the tail unit to improve track stability.
AD-3W
In a crew of three, there was a clear division of responsibilities. In addition to the pilot and the radar operator, there was another workplace for the radio operator, who kept constant radio contact with the aircraft carrier or guided fighters in the air. Based on the experience of operating TBM-3W2 aircraft, another purpose of the AD-3W was to search for submarines, for which a magnetometer was squeezed onto the aircraft. Also, the AN / APS-31 radar was tested on Skyraders, but it did not take root.
As a result, after all the experiments, they decided to abandon the anti-submarine functions, and the AD-4W with the AN / APS-20A radar became the standard version of the deck "flying radar picket". Compared to the original version, the characteristics of the detection range and reliability of the station have been significantly improved.
This modification, built in the number of 158 aircraft, replaced the worn out TBM-3W2 on the decks of aircraft carriers. Compared to the Avenger, the working conditions aboard the Skyrader were much more comfortable, and the new aircraft had an almost twice as large patrol radius - 650 km. However, the AD-4W inherited many of the disadvantages of the TBM-3W - the aircraft was single-engine, which, in the event of a power plant failure while flying over the ocean, left little chance for the crew to survive. Significant vibrations of the piston engine located next to the radar and communication equipment negatively affected its reliability. And due to the location of the radar antenna under the fuselage, the detection of high-altitude targets was difficult.
However, the radar Skyraders were highly regarded by the Navy, and they played a prominent role during the Korean War. The AD-3W and AD-4W aircraft were constantly hovering over the American aircraft carriers, warning of the approach of jet MiGs.
British AEW.1.
After several British piston carrier-based aircraft Sea Fury FB. Mk 11 from the aircraft carrier HMS Ocean (R68) were subjected to surprise attacks by the MiG-15, the British expressed a desire to purchase 50 carrier-based AWACS aircraft. They received the designation AEW.1 in the Royal Navy and served until 1962.
AD-5W
A further version of the development of the radar "Skyrader" was the AD-5W (since 1962 - EA-1E). In total, the American fleet received 239 vehicles of this modification. Compared to the AD-3W and AD-4W, the element base of the advanced avionics already contained a significant proportion of semiconductor elements, which significantly reduced the size and power consumption. Operation of the EA-1E in the US Navy continued until the mid-60s.
Already in the early 50s, single-engine radar patrol aircraft ceased to suit American admirals. After the emergence of intelligence information about the development of sea and air-based cruise missiles in the USSR, the American fleet needed an "air radar picket" with a larger radius and range than the Skyrader.
E-1B Tracer
The new aircraft, called the E-1B Tracer, equipped with a complete set of onboard equipment, took off for the first time on March 1, 1957. Serial construction of "Treser" continued until the beginning of 1958, a total of 88 vehicles were handed over to the fleet. The base for the new deck "radar picket" was the anti-submarine S-2F Tracker. The aircraft's crew consisted of four people: two pilots and two radar operators.
Unlike the first post-war American AWACS aircraft, where the AN / APS-20 station was used, a new AN / APS-82 radar was installed on the Tracer, which operated in the wavelength range of 30-100 cm. The radar was placed about a meter elevated above fuselage droplet-shaped fairing with dimensions 9, 76x6, 0x1, 25 m. This solution made it possible to reduce the "dead zone" due to the shading of the metal parts of the aircraft structure. Compared to the AD-5W, the detection range has increased and, in particular, the ability to select targets against the background of the water surface. In the absence of interference, the detection range of a high-altitude target of the B-29 type was 180 km, the radar information update rate was 10 seconds.
However, it soon became clear that the new aircraft was also not devoid of significant drawbacks. Despite the increased internal volume, there was no room on board for a combat control officer and his functions had to be performed by the co-pilot. In addition, the aircraft did not have equipment for the automated transmission of radar data, and the information was first transmitted by voice over the radio to the aircraft carrier, from where the fighters were already controlled. The limited carrying capacity of the base chassis prevented the introduction of a data processing and transmission operator into the crew, the installation of more modern equipment and the expansion of its composition. In addition, by the beginning of the 60s, the piston deck aircraft already looked archaic. All this significantly limited the service life of the E-1B in the US Navy, the last aircraft of this type was sent to storage in November 1977.
As already mentioned, the disadvantages of the first carrier-based radar patrol aircraft include small free volumes on board and a relatively short flight range and patrol duration. What, however, had to be put up with when used from the deck of an aircraft carrier. However, in the case of basing on the shore, nothing prevented the use of larger machines with a longer flight duration as a platform.
PB-1W
Simultaneously with the deck TBM-3W, the fleet ordered 24 four-engine PB-1W with the same AN / APS-20 radar. The radar antenna was located under a large drop-shaped fairing in place of the bomb bay. In addition to the radar, the PB-1W was equipped with a "friend or foe" radar identification system for aircraft and ships. In addition to aircraft with a lower radar location, at least one aircraft with a dorsal radar fairing was built.
Coast-based AWACS aircraft PB-1W were built on the basis of B-17G bombers. Compared to the "palubniks", heavy four-engine aircraft had several times greater flight range and patrol duration. And the living conditions on board the TBM-3W were much more comfortable, unlike deck aircraft, the radar operator did not have to sit hunched over due to the lack of free space. Now it is possible to have 2-3 shift operators and a command and control officer on board.
Like the deck TBM-3W, the land-based AWACS PB-1W did not make it to the war. The transfer of the first five aircraft to the US Navy took place in April 1946. Since the hostilities have already ended, all defensive weapons were dismantled from them, and the number of crew members was reduced from 10 to 8 people.
Aircraft PB-1W served on both the east and west coast of the continental United States. In 1952, four PB-1Ws were sent to Hawaii. In addition to controlling the airspace and controlling the actions of fighter aircraft, during flights, the operators were assigned the tasks of searching for submarines and reconnaissance of the weather. The characteristics of the AN / APS-20 radar made it possible to detect approaching hurricanes at a distance of more than 120 km and promptly notify of the threat. At the same time, the intensity of PB-1W flights was high. As the resource developed, the aircraft were to be decommissioned, the fleet parted with the last PB-1W in 1956.
The American Air Force began to deal with AWACS aircraft much later than the Navy and did not pay special attention to them at first. In 1951, three B-29 bombers were converted into AWACS aircraft. Aircraft with AN / APS-20C radar and jamming station were designated P2B-1S. For the most part, these machines were used not for patrol flights or fighter coordination, but for weather reconnaissance and participated in various kinds of test programs, experiments and exercises.
By that time, the Air Force had not yet decided on the role and place of the long-range radar patrol aircraft. Unlike the admirals, who still remembered the consequences of the devastating raid on Pearl Harbor and the kamikaze attacks, the Air Force generals relied on numerous ground-based radars and jet interceptors. However, soon after the creation of nuclear weapons in the USSR and the adoption of long-range bombers capable of reaching the continental territory of the United States and returning back, American strategists were forced to spend significant funds on improving the air defense system, including on aircraft and even airships carrying powerful radars detection of air targets. But this will be discussed in the second part of the review.
