The Aero Spacelines B-377SGT (Super Guppy Turbine) is a unique aircraft owned by NASA and used to transport outsized cargo for the agency. Although several were built, only one remains.
The origins of the Super Guppy go back to the 1940s and the Boeing B-29 bomber. During the war, Boeing developed a cargo version of the B-29, grafting an enlarged upper fuselage onto the B-29's relatively slender body. The resulting C-97 or civil B-377 was built in large numbers, with most bought by the U.S. Air Force as KC-97 tankers. The KC-97 served into the 1970s before finally succumbing to old age and yielding its place to the jet-powered KC-135.
Around 1960 the concept of further enlarging the upper fuselage emerged and the resulting Pregnant Guppy first flew in 1962. It retained the original tail surfaces and was powered by R-4360 piston engines. It proved invaluable in transporting large rocket modules across the country for space programs.
The Pregnant Guppy was succeeded by the Super Guppy, powered by turboprop engines and with enlarged tail surfaces. The Super Guppy was used by NASA and others to transport space program-related cargo and Airbus built two to transport large components for aircraft manufacture. Ultimately, Airbus replaced their Super Guppies with five Airbus-manufactured A300-600ST Beluga aircraft which carry components between the various Airbus factories in Europe.
The Super Guppy was updated along the way -- now only one NASA-owned aircraft remains.
https://en.wikipedia.org/wiki/Aero_S...es_Super_Guppy