Convair XC-99

Design capacity of the XC-99 was of cargo or 400 fully equipped soldiers on its double cargo decks. A cargo lift was installed for easier loading. The engines face rearward in a pusher configuration. Planned civil passenger variant The Convair Model 37 was a large civil passenger design derived from the XC-99 but was never built. The Model 37 was to be of similar proportions to the XC-99; length, wingspan, and a high-capacity, double-deck fuselage. The projected passenger load was to be 204, with an effective range of . Fifteen aircraft were ordered by Pan American Airways for transatlantic service. However, the fuel and oil consumption of the six Wasp Major radials powering the XC-99 and B-36 meant that the design was not economically viable, and the hoped-for turboprop powerplants did not materialize fast enough. The low number of orders was not sufficient to initiate production, and the project was abandoned. ==Operational history==

In July 1950, the XC-99 (AF Ser. No. 43-52436) flew its first cargo mission, "Operation Elephant". It transported of cargo, including engines and propellers for the B-36, from San Diego to Kelly Air Force Base in San Antonio, Texas, a record it would later break when it lifted from an airfield at elevation. In 1951, the aircraft was retrofitted with 3,800hp Pratt & Whitney R-4360-53 engines, landing gear was strengthened and a cargo-loading system installed, including an internal elevator. Bins were developed to enable quick loading of the aircraft - it was estimated the aircraft could be loaded in as little as 30 minutes. In August 1953, the XC-99 would make its longest flight, , to Rhein-Main Air Base, Germany, by way of Kindley Air Force Base, Bermuda and Lajes Field in the Azores. It carried more than each way. It attracted much attention everywhere it flew. The US Air Force determined that it had no need for such a large, long-range transport at that time, and no more were ordered. The sole XC-99 served until 1957, including much use during the Korean War. It made twice weekly trips from Kelly AFB to the aircraft depot at McClellan Air Force Base, California, transporting supplies and parts for the B-36 bomber while returning by way of other bases or depots making pick-ups and deliveries along the way. ==Retirement and preservation==

, Texas while attached to the Military Air Transport Service 1700th Air Transport Group, 1954. Note San Antonio Air Materiel Area (SAAMA) tail marking, indicating the aircraft was assigned to the Air Materiel Command. The aircraft was put on display at Kelly AFB near San Antonio, Texas, in 1957. Deterioration of the airframe due to the high magnesium content was beyond local abilities to address. The aircraft was later moved to a grassy field near the base and in 1993 the USAF moved it back to the Kelly AFB. In 1995, Kelly AFB was identified for closure via BRAC, although some portions would remain under USAF control as the Kelly Field Annex to adjacent Lackland AFB, it was deemed that a new location be identified for the XC-99. Disassembly of the aircraft began at Kelly Field in April 2004 and the airframe was moved in pieces from Kelly to the National Museum of the United States Air Force (NMUSAF) at Wright-Patterson Air Force Base. By the summer of 2008, the transfer was complete and the parts were lying outside the museum. The aircraft had continued to suffer additional corrosion during its years in Texas and was found to be in worse condition than expected, with the restoration task being beyond the resources of the museum in a realistic time scale. Some major components such as the wing spar would need to be completely replaced. The NMUSAF's plans for the restoration and display of the XC-99 are displayed in a case with a 1:72 scale model made by Lt Col Howard T. Meek, USAF (Ret). In an effort to preserve the aircraft for future restoration, the XC-99 was later moved incrementally to the 309th Aerospace Maintenance and Regeneration Group (309 AMARG) storage facility at Davis–Monthan Air Force Base, in Tucson, Arizona, where it will remain, in an area containing other aircraft belonging to the NMUSAF until the museum is able to restore it. ==Specifications (XC-99)==