A post–World War II revision of the Boeing B-29 Superfortress, it was fitted with more powerful Pratt & Whitney R-4360 radial engines, stronger structure, a taller tail fin, and other improvements.

These tanker and hurricane-hunter variants were retired in March 1965 after metal fatigue and corrosion were found in the wreckage of a KB-50J, 48-065, that crashed on 14 October 1964.

[3][4] The planned Wasp-Major powered bomber, the B-29D, was to incorporate considerable changes in addition to the engine installation tested in the XB-44.

The use of a new alloy of aluminum, 75-S rather than the existing 24ST, gave a wing that was both stronger and lighter, while the undercarriage was strengthened to allow the aircraft to operate at weights of up to 40,000 pounds (18,000 kg) greater than the B-29.

A larger vertical fin and rudder (which could fold to allow the aircraft to fit into existing hangars) and enlarged flaps were provided to deal with the increased engine power and weight, respectively.

[3] The last airframe of the initial order was held back for modification to the prototype YB-50C, a planned version to be powered by R-4360-43 turbo-compound engines.

Most of the B-50As were fitted with the early "looped hose" refueling system, developed by the British company Flight Refuelling Limited, in which the receiving aircraft would use a grapple to catch a line trailed by the tanker aircraft (normally a Boeing KB-29) before hauling over the fuel line to allow transfer of fuel to begin.

The B-50 was nicknamed "Andy Gump", because the redesigned engine nacelles reminded aircrew of the chinless newspaper comic character popular at the time.

[14] B-50s from the 4925th Special Weapons Group of Kirtland Air Force Base in Albuquerque, New Mexico dropped atomic bombs in a series of tests in Frenchman Flat, Nevada from 1951 to 1953.

[15] The 301st Bombardment Wing at MacDill Air Force Base, Florida received some B-50As reassigned from Davis–Monthan in early 1951, but used them for non-operational training pending the delivery of B-47A Stratojets in June 1951.

[16] The vast northern borders of the Soviet Union were wide open in many places during the early Cold War years, with little defensive radar coverage and limited detection capability.

[17] The deployment of the MiG-15 interceptor in the early 1950s made these flights exceedingly hazardous, with several being shot down by Soviet air defenses and the wreckage being examined by intelligence personnel.

RB-50 missions over Soviet territory ended by 1954, replaced by the RB-47 Stratojet intelligence aircraft that could fly higher at near-supersonic speed.

[17][failed verification] The B-47 Stratojet was manufactured in large numbers beginning in 1953 and eventually replaced the B-50Ds in SAC service; the last being retired in 1955.

As tankers, KB-50s had extensively reinforced outer wing panels, the necessary equipment to air-refuel simultaneously three fighter-type aircraft by the probe and drogue method, and removed defensive armament.

Some were deployed to Thailand and flew refueling missions over Indochina in the early years of the Vietnam War until being retired in March 1965 due to metal fatigue and corrosion.

After the weather reconnaissance fleet was grounded in May 1960 because of fuel leaks, plans were set in motion in 1962 to modify B-47 Stratojets being phased out of SAC to replace it in the role.

Lucky Lady II was disassembled after a serious accident, and its forward fuselage is stored outside at Planes of Fame Air Museum in Chino, California.