Saturday, April 16, 2011

Flying Radar in the Past and Present - Part I

by Ilya Kramnik

The first aircraft with onboard radar do not differ great potential - the maximum they could get of their radars, is to help locate in poor weather or night-time enemy aircraft at a distance of several kilometers and ensure convergence to the distance to the effective fire-board weapons. Since then the situation has changed radically. Today, the winged machines Airborne Warning and Control System (AWACS) aircraft - a key element of air power in developed countries.

And the activities to establish the aircraft radar appeared almost immediately after the creation of the first workable radar in the late 30's, and soon broke out World War II spurred the only work in this area.

Based on the torpedo, bombers and submarines hunters

Followed by fighter jets on-board radar almost simultaneously started to equip patrol aircraft naval aviation, making it easier for them to find enemy ships and submarines. But none of these machines could not claim the role of airborne early warning aircraft (AWACS), it remained the lot of large ground-based and ship radars, and the management of air operations from flying command post and no one had ever thought of it before.

The most acute need for machines AEW manifested itself in the battles of the Pacific, where the rare islands, scattered on a vast distance from each other, were not given the opportunity to create an operational network of ground-based radar, and onboard radars of warships did not make it possible to glance beyond the horizon at the distance, sufficient in order to notch the approaching hostile aircraft.

"In 10 hours 55 minutes radar detected a large group of enemy aircraft approaching from the northeast. In 11 hours 13 minutes observers "Lexington" noticed the first Japanese plane - so U.S. Admiral Frederick Sherman recalls the beginning of the Japanese air attack aircraft carrier Lexington in the battle of the Coral Sea in May 1942. - The only radar one of the first sample, which was on our board, revealed the enemy planes at a distance of 68 miles, but did not give any data on the height of their flight ... It was also difficult to distinguish their planes from the enemy. "

Lack of information about the altitude of the enemy vehicles are not allowed to send them advance toward the fighters. Was a great risk: the pilots simply could not find the enemy, especially given the fact that the war had just begun and the U.S. Navy still did not know the standard altitude approach to the target of Japanese attack planes. As a result pilots, who took off from “Lexington”, intercepted the Japanese only in twenty miles from the aircraft carrier and at this distance for the purpose to stop or to at least thin out wave of 60 (according to others data - 69) torpedo bombers, dive-bombers and fighters was no longer possible.

"In this battle, we learned: in order to thwart an air attack, it is necessary to intercept the enemy as far away from the aircraft carriers. We must not forget that this was the first in the history of the duel aircraft carriers, and we learn our tactics, in practice, "- says Sherman, in his book" War in the Pacific. Carriers in combat. "

The battle of the Coral Sea ended for the Americans lost, "Lexington", spurred the development of airborne early warning aircraft, or using the Western term, Airborne Early Warning (AEW).

Not surprisingly, the world's first machine was a modification of the famous AWACS torpedo "Avenger" - TBM-3W. This carrier-based aircraft had been created under the "Cadillac" by a team at the Massachusetts Institute of Technology (MIT) and received a decimeter radar AN/APS-20 – “brainchild" of companies Hazeltine Corporation and General Electric. The first sample tested the system in February 1944 and in August the same year for the first time took to the skies "Avenger" in the form of aircraft airborne detection. The first drill machines of this type received by the Navy at the end of 1944 and the "baptism of fire" was in the Battle of Okinawa in March of 1945.They were able to identify the air group and individual enemy aircraft at distances up to 100 miles.

"Avenger" - an aircraft that could solve a problem of AWACS, however the possibilities for control of the radar operator, located in the cockpit two-seater aircraft, was clearly not enough. Data from the board TBM-3W were transferred in the ground (or ship) information center, where on the radio channel “were dropped” image from the screen PPI and the coordinate the orientations of antenna RLS. Several such aircraft ensured command center with the valuable information about the tactical situation.

However, delay in data transfer and processing; time to time led to the fact that the massive raids and some enemy planes, and the whole group of them (mostly suicide) broke through to the American squadron, before the US machine had time to put the fighters. In addition, the location of the mobile antenna is limited under the fuselage substantially narrowed the field of radar. Considerable difficulties arose with the discovery of low-flying targets. As a result, day and night patrols to support the regime has not been possible, for there were simply not enough machines.

Nevertheless, for all but project "Cadillac" was considered a success and launched the "Cadillac-II”. As part of this project was to create not just a flying radar, and airborne command post. The basis of the new system put all the same radar AN/APS-20. Looking ahead, we note that it can be considered one of the best examples in the history of radar technology.Developed in 1943-1944 station will be used in different countries for more than 10 different platforms, including helicopters and airships, and will serve until the end of the 80's.

Another carrier elected AN/APS-20 with refurbished "flying fortress" Boeing B-17 "- the plane PB-1W. Flight range of cars reached 5500 kilometers, it could fly more than 12 hours, and in the fuselage former bomber managed to place several radar operators, who analyzed the data in real time and immediately passed it on airborne aircraft. However, in practice data came first to the ground command center, from where it was carried out management battle.

C TBM-3W and PB-1W began the evolution of the two branches of AWACS aircraft - the deck and base. Already in the second half of the 40ies TBM-3W were supplemented by machines AF-2W Guardian and AD-3W Skyraider, but they retain the same fundamental flaws that "Avenger": a short while on patrol, the lack of viewing angle radar.

The yield was found in redeveloping the antisubmarine aircraft S-2 Tracker. The machine is equipped with new radar AN/APS-82c rotating antenna installed in the fairing on the fuselage, received index E-1. From the name of the letter has disappeared «k», and "tracker" was the "tracer". "Pathfinder" - translated as Tracer in Russian - was built from 1955 to 1958. In total 88 aircraft were produced. They were the main deck flying radars the U.S. Navy until the late 60's, when to replace them came the famous E-2 "Hawkeye".


Sharp stars

Almost simultaneously with the "tracer" was born on the plane, which was destined for many years to become the basis of AWACS in the Air Force and U.S. Navy. Warning Star (Zorkaya star) or according to navy index WV-2 is created on the basis of one of the finest piston aircraft - the Lockheed L-1049 Super Constellation. The Americans built the 232 planes of this type. They had two main radar mounted on top and bottom of the fuselage. In the upper fairing located radar antenna AN/APS-45, at the bottom - all the same AN/APS-20.

"Sharp stars" to become masters of all trades - they were an important element in the US-Canadian air defense system NORAD, carrying on combat duty in Europe, Japan and Southeast Asia. Planes of this type have participated in many local conflicts, and isolated incidents of cold war.

Finest hour, and at the same time the beginning of the sunset "vigilant" stars turned out to be the Vietnam War. EC-121 U.S. Air Force came here in 1965, carrying out tasks in addition to the role of AWACS aircraft transponders. In October of 1967 with EC-121 held a historic event for the whole system - to intercept North Vietnamese MiG-21, in which control over the actions of American destroyers for the first time carried out directly by the operator machine AEW.

EC-121 were the same for all participants as a major U.S. air operations during the Vietnam campaign. Gradual improvement of the equipment of these aircraft have made it possible, though to a limited extent, control the fight. The main role yet still remain in "the land" where the channels data to automatically send information from the radar, "Sharp" stars.

Finally, in the 60-70's before the AWACS aircraft set another challenge - to monitor the electronic activity of the enemy. EC-121/WV-2 can deal with this subject to appropriate additional equipment. But to have the system information about the environment, requiring no additional information together for analysis, needed a radically new machine. Cell base 40-50ies could not provide new tasks, they had to solve the next generation of aircraft. They became the E-3 Sentry, which can be regarded as the first full AWACS aircraft, or - as this system is denoted in the West - AWACS.


Our [Russian] answer to Uncle Sam

In Soviet experiments on the radar aboard the aircraft broke out almost simultaneously with other developed countries - in the early 40's. With regards to AEW, our country have managed to create later than in the U.S.. The reasons for the backlog are clear - for the Americans a crucial element of global military and political power was (and is!) Control over the ocean, which, since 40ies was impossible without a long range air-based radar.

For the Soviet Union was no less critical control over the continent, and in the Great Patriotic War in the USSR began to building an extensive layered and redundant network of ground-based radars, to provide in the end creating a continuous radar field from Central Europe to Kamchatka. Its density and the lower limit of detection were not uniform, and a number of ways - clearly insufficient, especially for the Arctic. It is the Arctic that  has become the main route for intercontinental bombers on both sides in the case of nuclear war. But it is safe to cover a huge area just north of the Soviet land-based radar failed. As a result, in 1958 it became necessary to construct aircraft and AWACS aircraft to intercept long-range bombers. Both planes were born in the Tupolev Design Bureau. Flying the radar received an index of Tu-126 interceptor - Tu-28, then - Tu-128.

Tupolev Design Bureau tasked with developing a platform for the AWACS system, because this team has unique experience in building large aircraft. That the basis for the new system should serve as a vehicle of a growing family of Tu-95, beyond doubt, but what exactly? True, the very "95 th" is no longer - the diameter of the fuselage are not allowed to place dimensional equipment and radio crew. The prototype for the Tu-126 eventually became the Tu-114 - designed on the basis of the bomber passenger liner, featuring a large internal volume. Radar operator with their remotes in the front and middle part of a converted passenger cabin, located at the rear of the radar units, systems, electronic intelligence and communications.Aerial surveillance radar "Liana" was mounted in a fairing on the pylon above the fuselage.

Losing priority to Americans, namely the Soviet AWACS aircraft laid the foundation architecture of subsequent generations of aircraft in this class. Tu-126 became the first "big" plane, equipped with a rotating radar antenna, which dramatically increased the capabilities of the platform. The first flight of the Tu-126 held on 23 January 1962, but production aircraft delivered to Air Force 1966-1967. A total of eight cars built. All of them belonged to the 67th separate aviation squadron AWACS team based at Šiauliai (Lithuanian SSR).

Instrument aircraft, developed by NII-17 (known as "Vega"), can detect aerial targets at a distance of 100-350 kilometers, surface - up to 400 kilometers, the radar radiation at a distance of up to 500-600 kilometers, to transfer data to command centers and air defense Navy at ranges up to 2000 kilometers. Machine could be used not only for data but also for the guidance of interceptors at the target, making it a complete system of AEW.

For all the novelty of the Tu-126 there were disadvantages. Like the Western competitors, it had serious difficulties with the discovery of targets against the background of the earth. At the turn of the 60-70's this led to the fact that because of the changing tactics of the military use of aviation, NATO effectiveness of the Soviet spy fell to critical levels. To detect low-flying machines had to change tactics Patrol: now flights took place at low altitudes (within 500-600 meters) and the load on the crew is very noticeably increased. In addition, limited capacity of electronic equipment did not allow the Tu-126 to control the action more or less large aviation forces.

Besides the general misfortunes for all aircraft [AEW] of the first generations Tu-126  suffered one additional “ailment” of purely domestic origin. American intelligence officers were re-equipped from the comfortable airliners and in many respects preserved their conveniences. Tu-126, in spite of straight relationship Tu-114, by more contemporary and not less more comfortable than L-1049, was deprived of all civil “excesses”. If decent conditions for prolonged crew stay were ensured in the overseas machine, then aboard Tu-126 reigned a maximally situation.

Actually aircraft was the duralumin “box”, in which practically there is no noise-isolation. In the sections stood the most powerful rumble, sources of which were engines, screws, equipment “of liana”, and at the same time and resounding elements of construction, including leading into the pylon radar iron stairs. The revetment of metallic elements was absent completely. The accumulation in flight of static electricity led to the fact that after only three hours after takeoff metal it was not possible to undertake by hand. The sections were not heated on the earth with the shut-down engines, and in winter crew occupied its work sites, sitting down into the icy armchairs. Most difficultly it was necessary for the pilots, who leaned by back on the armored backrests, sheathed by the thin layer of leatherette. Inflight refuelling made flights much longer and extended the discomfort over a longer period.Radiculitis and other consequences of a cold became the occupational diseases of pilot- intelligence officers.

The main routes of Tu-126 lies in the Arctic - or in the direction of the New Earth, or to Franz Josef Land. Were frequent and flights over the Baltic Sea and the North Atlantic. During these raids, the Tu-126 is often quite tight contact with warplanes and warships of NATO Air Forces.

The above-mentioned drawbacks as the Tu-126 AEW system common to all flying radar of the first generations, led to the fact that in the 70 years both in the USSR and the U.S. began to develop a new plane. Aircraft was meant to be a real flying command center, able to detect targets, including against the background of the land, control the actions of large formations of aircraft and transmit information in real time. Such aircraft, "our answer" to the E-3 Sentry, was built on a military transport Il-76 AWACS aircraft A-50.


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