Convair XC-99

XC-99
The sole XC-99 in its early days of operation, before a nose radome was fitted.
Role	Heavy transport
Manufacturer	Convair
First flight	23 November 1947
Introduction	23 November 1949
Retired	1957
Primary user	United States Air Force
Number built	1
Developed from	Convair B-36
Type	Prototype
Serial	43-52436
Total hours	7,400 hours
Preserved at	National Museum of the United States Air Force in Dayton, Ohio

The Convair XC-99, 43-52436, was a prototype heavy cargo aircraft built by Convair for the United States Air Force. It was the largest piston-engined land-based transport aircraft ever built, and was developed from the B-36 bomber, sharing the wings and some other structures with it. The first flight was on 23 November 1947 in San Diego, California, and after testing it was delivered to the Air Force on 23 November 1949.

Design and development

Design capacity of the XC-99 was 100,000 lb (45,000 kg) of cargo or 400 fully equipped troops on its double cargo decks. A cargo lift was installed for easier loading. The engines face rearward in a pusher configuration.

Operational history

In July 1950 the XC-99 flew its first cargo mission, "Operation Elephant." It transported 101,266 pounds (45,933 kg) 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 104,000 lb (47,200 kg) from an airfield at 5,000 ft (1,500 m) elevation. In August 1953, the XC-99 would make its longest flight, 12,000 mi (19,000 km), to Rhein-Main Air Base, Germany, by way of Bermuda and the Azores. It carried more than 60,000 lb (27,000 kg) 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 AFB, 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. During its operational life the XC-99 logged over 7,400 hours total time, and transported more than 60,000,000 lbs of cargo.^[1] The aircraft made its last flight on 19 March 1957, landing at Kelly Air Force Base, where it would remain for the next 47 years.^[2] The United States Air Force Museum in Dayton, Ohio, requested that the aircraft be flown there for display, but the Air Force refused due to the $7,400 cost of the flight.

Retirement and display

The XC-99 landing during trials.

The aircraft was put on display at Kelly Air Force Base near San Antonio, Texas. During the 1960s, it was considered for restoration by the San Antonio Air Logistics Center at Kelly AFB, but the deterioration of the airframe due to the high magnesium content led to the abandonment of that plan. The aircraft was later moved to a grassy field near the base. In 1993, the USAF moved it back to the Kelly AFB tarmac (29°22'27.37" N 98°35'13.74" W). It was planned to move the XC-99 via road to the National Museum of the United States Air Force at Wright-Patterson Air Force Base, Ohio, restore and reassemble it, and put it on display in the USAF Museum's collection of experimental aircraft. Ultimately, transporting the massive aircraft by ground proved impractical and too expensive.

Base Realignment and Closure (BRAC) action in 1995 resulted in the partial closure and realignment of Kelly AFB, with most of the former San Antonio Air Logistics Center becoming civilianized and renamed Kelly USA, while the runway and those flight line areas supporting C-5 and F-16 flight operations of the Air Force Reserve Command's 433d Airlift Wing and the Texas Air National Guard's 149th Fighter Wing reverted to adjacent Lackland AFB and was renamed Lackland AFB/Kelly Field Annex.

Disassembly of the aircraft began at Kelly Field in April 2004. Portions of the airframe were then airlifted from Kelly to Wright-Patterson Air Force Base near Dayton, Ohio.^[3] Upon arrival at Wright-Patterson's active base, the parts had to be further moved by truck several miles to the museum side of the base. Transporting the XC-99 components taxed the C-5A's cargo capacity, as the largest piece moved intact was over 75 feet by 13 ft. By the summer of 2008, the XC-99 had been completely transferred to Dayton and was lying on the ramp outside the museum's restoration facility.^{[citation needed]}

Upon examination, the aircraft was found to have suffered from considerable corrosion, which was not unexpected considering it had remained outside for over 50 years. The wing spar was found to be too badly corroded to restore, and a new replacement would need to be fabricated. A full restoration is being performed by the restoration crew of the Air Force Museum, although no timetable exists at this time. As of May 2011, the corrosion control of the center wing boxes was nearing completion. Once this portion of the project is finished, the XC-99 will be reassembled and the restoration work started.^[4]

Following restoration, the aircraft was expected to be displayed inside in one of the museum's new hangars. Like its relative the B-36, it is expected to become a showpiece of the museum. Once all aircraft have been moved from the Museum's current "Research and Development Hangar" or "Presidential Hangar" to a new display hangar planned to be added onto the main Museum buildings, the XC-99 restoration project will move into the vacated hangar, where visitors will be able to watch the restoration in progress. Upon completion, the XC-99 will remain on display in either the former R&D hangar, or Presidential Hangar.^[5]

Pending the restoration and display of the XC-99, in an effort to educate visitors about the aircraft the Air Force Museum has placed a model of the XC-99 on display in its Post-Cold War Gallery. The model, in approximately 1/72 scale, was constructed by a member of the museum's restoration staff. An explanation of the Museum's plans for the restoration and display of the XC-99 is located in the case with the model.^[1]

Recent developments

Because the XC-99 arrived in worse condition than had been expected the magnitude of the restoration was greater than the restoration staff was able to quickly accommodate.^[4] The fuselage was placed in pieces along the flight line in front of the restoration facility while plans were developed for the aircraft's restoration.</ref> The aircraft will be transported to the base in pieces by C-5 Galaxy transport aircraft as opportunities become available.^[3] During the seven years the aircraft has remained exposed to the elements, it has continued to deteriorate.^[6] In an effort to protect the aircraft, in the summer of 2011, a decision was made by the restoration staff to move the disassembled XC-99 to the Military Air Transport Service storage facility at Davis–Monthan Air Force Base, near Tucson, Arizona.^[7] The XC-99 will remain at Davis–Monthan Air Force Base, in an area containing other aircraft belonging to the Museum, until the restoration staff has the time and resources to perform a full restoration.^[8]

Planned civil 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; 182 ft 6 in (55.63 m) length, 230 ft (70 m) wingspan, and a high-capacity, double-deck fuselage. The projected passenger load was to be 204, and the effective range 4,200 mi (6,800 km).

Fifteen aircraft were ordered by Pan American for transatlantic service. However, the fuel and oil consumption of the six 3,500 hp (2,600 kW) 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 were not sufficient to initiate production, and the project was abandoned.

Survivors

• XC-99 s/n 43-52436 is part of the National Museum of the United States Air Force collection at Wright-Patterson AFB in Dayton, Ohio. The aircraft is disassembled, and is stored at the Davis–Monthan Air Force Base restoration facility.^[8]

Specifications (XC-99)

Data from General Dynamics Aircraft and their Predecessors^[9]

General characteristics

• Crew: Five duty + five reserve crew
• Capacity: 400 troops
• Payload: 100,000 lb (45,000 kg)
• Length: 182 ft 6 in (55.64 m)
• Wingspan: 230 ft 0 in (70.12 m)
• Height: 57 ft 6 in (17.53 m)
• Wing area: 4,772 ft² (443.5 m²)
• Empty weight: 135,232 lb (61,469 kg)
• Loaded weight: 265,000 lb (120,455 kg)
• Max takeoff weight: 320,000 lb (145,455 kg)
• Powerplant: 6 × Pratt & Whitney R-4360-41 Wasp Major 28-cylinder air-cooled radial engine, 3,500 hp (2,611 kW) each

Performance

• Maximum speed: 307 mph (267 knots, 494 km/h)
• Range: 8,100 mi (7,043 nmi, 13,041 km)
• Service ceiling: 30,000 ft (9,150 m)

See also

Related development

• B-36 Peacemaker
  

Aircraft of comparable role, configuration and era

• Bristol Brabazon
• Lockheed R6V Constitution
• Saunders-Roe Princess
• Tupolev ANT-20
  

Related lists

• List of military aircraft of the United States
  

References

Notes

1. ^ ^{a b} "Factsheet: Convair XC-99 Model." National Museum of the United States Air Force. Retrieved: 14 September 2011.
2. ^ "Factsheet: Convair XC-99." National Museum of the United States Air Force. Retrieved: 13 September 2011.
3. ^ ^{a b} Hill, 1st Lt Bruce R., Jr. "XC-99 begins piece-by-piece trip to Air Force Museum." 433rd Airlift Wing Public Affairs: USAF, 22 April 2004. Retrieved: 2 November 2011.
4. ^ ^{a b} "Exhibit Restoration Status." National Museum of the United States Air Force, May 2011.
5. ^ "Tours." National Museum of the United States Air Force. Retrieved: 13 September 2011.
6. ^ "Restoration: XC-99." National Museum of the United States Air Force, July 2011.
7. ^ "XC-99 Disassembled." Wikimapia. Retrieved: 2 November 2011.
8. ^ ^{a b} Lockett, Brian. "Convair XC-99 and Model 37." Goleta Air and Space Museum via air-and-space.com, 19 February 2011. Retrieved: 2 November 2011.
9. ^ Wegg 1990, p. 98.

Bibliography

• Dorr, Robert F. "Saving the XC-99." Air Force Times, 12 August 1998.
• Dorr, Robert F. "XC-99 is a treasure." Air Force Times, 10 June 2000.
• Jacobsen, Meyers K. Convair B-36: A Comprehensive History of America's "Big Stick". Atglen, Pennsylvania: Schiffer Military History, 1997. ISBN 0-7643-0974-9.
• Jacobsen, Meyers K. Convair B-36: A Photo Chronicle. Atglen, Pennsylvania: Schiffer Military History, 1999. ISBN 0-7643-0974-9.
• Jacobsen, Meyers K and Ray Wagner. B-36 in Action (Aircraft in Action Number 42). Carrollton, TX: Squadron/Signal Publications Inc., 1980. ISBN 0-89747-101-6.
• Jenkins, Dennis R. Convair B-36 Peacemaker. St. Paul, Minnesota: Specialty Press Publishers and Wholesalers, 1999. ISBN 1-58007-019-1.
• Johnsen, Frederick A. Thundering Peacemaker, the B-36 Story in Words and Pictures. Tacoma, WA: Bomber Books, 1978.
• Miller, Jay and Roger Cripliver. "B-36: The Ponderous Peacemaker." Aviation Quarterly, Vol. 4, No. 4, 1978.
• Wegg, John. General Dynamics Aircraft and their Predecessors. London: Putnam, 1990. ISBN 0-85177-833-X.

External links

• Goleta Air and Space Museum Convair XC-99 and Model 37
• 'U.S. To Europe With 50 tons", Popular Science, March 1950, early article with drawing of first layout of XC-99
• "Biggest Air Freighter Goes To War" 1951 article on first operational use of XC-99, photos and drawings