Developed from the Navy's A-3D Skywarrior, the B-66 was extensively redesigned to meet Air Force needs for a tactical light bomber and reconnaissance aircraft. The U.S.A.F. version first flew on 25 June 1954 as the RB-66A, which was originally designed for all-weather night photographic reconnaissance. The first production model, the RB-66B, first flew on 28 June 1954, and with its reconnaissance capability deleted, the B-66B served with Tactical Air Command as a light bomber carrying conventional or nuclear weapons. A more specialized reconnaissance version, the RB-66C, first flew on 29 October 1955 and had a pressurized four-man electronic countermeasure compartment between the front and rear fuselage tanks. EB-66B, C, and E electronic countermeasure versions of the RB-66C were used as protective cover for Air Force and Navy fighters against enemy surface-to-air missiles and radar-guided antiaircraft weapons during the latter part of the Vietnam conflict. Electronic equipment and two observers were carried in the fuselage, and the tail armament of two 20mm guns in a radar-controlled turret was retained. This WB-66D was flown to Kelly A.F.B. on 28 June 1976 from Westinghouse Corporation in Baltimore, M.D., where it had been used in a special project since 1969; it was the last B-66 flown. This aerospace vehicle, serial number 55-390, is part of the U.S.A.F. Heritage Program Collection.