The Boeing C-97 Stratofreighter is a long-range heavy military cargo aircraft developed from the B-29 and B-50 bombers. Design began in 1942. The first of three prototype XC-97s flew on 9 November 1944 and the first of six service-test YC-97s flew on 11 March 1947. 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 eight or "double-bubble" section) and they had the B-29 vertical tail with the gunner's position walled off. The first of three heavily revised YC-97A incorporating a wing with 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 sole YC-97B, all production C-97s, KC-97s and civilian Stratocruiser aircraft. Between 1947 and 1958, 888 C-97s in several versions were built, 811 being KC-97 tankers. C-97s served in the Berlin Airlift, the Korean War, and the Vietnam War. Some aircraft served as flying command posts for the Strategic Air Command, while others were modified for use in Aerospace Rescue and Recovery Squadrons (ARRS). The C-97 Stratofreighter was developed towards the end of World War II by fitting a second lobe on top of the fuselage and wings of the B-29 Superfortress with the tail, wing, and engine layout being nearly identical. The XC-97 and YC-97 can be distinguished from the Boeing 377 Stratocruiser and later C-97s by the shorter fin, and later ones by the flying boom and jet engines on the tanker models. The prototype XC-97 was powered by the same 2,200 hp (1,600 kW) Wright R-3350 engines as used in the B-29. The XC-97 took off for its first flight on November 9, 1944, just after the death of Boeing president Philip G. Johnson. 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 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 doors could not be opened in flight, but could be removed to carry out air drops. The C-97 had a useful payload of 35,000 lb (16,000 kg), which could include two 2½-ton trucks, towed artillery, or light tracked vehicles such as the M56 Scorpion. The C-97 featured cabin pressurization, which made long flights more comfortable. 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. The first Stratocruiser flew on July 8, 1947. Only 56 were built. Number built 77 (plus 811 tankers) For operational history and details of the 25 variants, click here.
