All nine were based on the 24ST alloy structure and Wright R-3350 engines of the B-29, but with a larger-diameter fuselage upper lobe (making a figure of eight or "double-bubble" section) and they had the B-29 vertical tail with the gunner's position blanked off.

The first of three heavily revised YC-97A incorporating the re-engineered wing (higher-strength 75ST alloy), taller vertical tail and larger Pratt & Whitney R-4360 engines of the B-50 bomber, flew on 28 January 1948 and was the basis of the subsequent sole YC-97B, all production C-97s, KC-97s and civilian Stratocruiser aircraft.

On 9 January 1945, the first prototype, piloted by Major Curtin L. Reinhardt, flew from Seattle to Washington, D.C. in 6 hours 4 minutes, an average speed of 383 mph (616 km/h) with 20,000 lb (9,100 kg) of cargo.

The tenth and all subsequent aircraft were fitted with the 3,500 hp (2,600 kW) Pratt & Whitney Wasp Major engines and taller fin and rudder of the B-50 Superfortress.

[3] The C-97 had clamshell doors under its tail so that two retractable ramps could be used to drive in cargo, but it was not a tactical airlifter able to deliver to primitive forward bases.

The C-97 was developed into the civilian Boeing 377 Stratocruiser, a transoceanic airliner that could be fitted with sleeper cabins and featured a lower deck lounge.

[7] One Israeli C-97 was downed by an Egyptian SA-2 Guideline missile on 17 September 1971, while flying as an electronic counter-measures platform some 12 miles from the Suez Canal.

[8][9] The following Air Force wing organizations flew the various C-97 models at some time during their existence:[15] – Westchester County Airport, New York (1962–1969) Data from Boeing C-97 Stratofreighter[34][35][36]General characteristics Performance