Lockheed WV-2 / EC-121 Warning Star
The need for a effective airborne early warning system was recognised towards the end of WW2 when a number of US Navy Grumman Avenger torpedo-bombers were fitted with the AN/APS-20 radar. To increase the loiter time of the AEW system, after the war ended the US Navy fitted the same radar system into modified B-17 bombers, re-designated PB-1Ws, although being land-based limited their effectiveness for 'blue-water' operations. Although the PB-1W was effective, it was cramped and as a modified bomber was a compromise - what was needed was a larger aircraft with more space for equipment and personnel together with greater endurance.
To meet the US navy requirement Lockheed modified the design of their Model 1049 Super Constellation airliner by adding an APS-20 search radar in a ventral radome together with a APS-45 height-finding radar in a large radome mounted on top of the fuselage. Inside the cabin were 5 operators positions and the internal communications system included a television system which allowed each controller to read data written on a central camera monitored display board. The aircraft could act as a Combat Information Centre (CIC), talking directly to ships, shore bases and other aircraft. On long missions up to 32 crewmen were carried.
The aircraft entered service with the US Navy in early 1953 with the designation WV-2 and were immediately used to provide radar coverage over the eastern ocean approaches to the USA - an Atlantic barrier. Patrol flights were maintained 24 hours a day, seven days a week with initially four WV-2 aircraft always out over the ocean on 12 hour sorties, although the number of aircraft was later cut to two. However, in winter weather conditions operating out of US Naval Air Station Argentia in Newfoundland proved challenging to say the least. Atlantic Barrier operations ended in 1961 after the DEW line was extended across Greenland, although residual patrols to fill in a gap in the Greenland, Iceland, UK (GIUK) barrier continued until 1 Sep 1965. Pacific barrier operations began in Jan 1956 with patrols off the west coast of America and out of Midway Island towards Adak Island in the Aleutian Islands. The Pacific barrier patrols continued until 1965. Another US Navy version, designated the WV-2Q, operated in the ELINT role during the Vietnam War.
The capability of the WV-2 made a big impression on the USAF, who were beginning to finally address the lack of an effective AEW aircraft in their inventory, and in 1951 they finally ordered the aircraft. In USAF service the aircraft was designated the EC-121C Warning Star. In the Vietnam War a number of EC-121, nicknamed 'Big Eye' and 'College Eye', aircraft provided early warning of MiG activity. The USAF ELINT version of this aircraft, designated the EC-121M, also operated in the conflict in South East Asia.
The WV-2 / EC-121 Warning Star remained in service until 1978.