WV-2/EC-121K BuNo 141297. Ex-USN, served with the VWs and Barrier Squadrons and the Naval Research Laboratory out of NAS Patuxent River, painted as an ADC EC-121 - Mark Morgan.
The housing on top of the fuselage is for an AN/APS-45 height-finding radar and the large belly radome was for the AN/APS-20 series search radar. Both had a long service life. The APS-20 was used on many different airframes and with other Allied air forces. Its design allowed it to be used for antiair warfare, antisurface warfare, and anti submarine warfare. The degree to which the APS-20 could be modified also made it attractive to different DoD branches for R&D. - David P. Murphy
Lockheed started work on a large passenger plane in the late 1930s. This eventually became the Constellation, whose production started in 1943 for the USAAF and then as a passenger liner for TWA in 1945. The unusual three tail configuration was to allow the relatively large plane to fit in existing hangars, since a single tail would have been much taller to get the same amount of surface area.
The first Constellation is the WV-2/EC-121K Mark refers to. It has the big top and less visible bottom ventral domes. The silver Constellation was used by both General Douglas MacArthur and later General Mathew Ridgeway during the Korean War and is beautifully preserved at Planes of Fame in Arizona. The last one is at Udvar Hazy, near Washington, DC. - Narayan Sengupta