Chase Aircraft designed the first all-metal transport glider, the XCG-18, followed by the larger and more efficient MS-8 Avitruk model. This was ordered on March 5, 1948 by the USAF in both piston-powered and un-powered forms as the XC-123 (47-786) and XG-20 (47-787). The first flights were made at October 14, 1949 and April 26, 1950 respectively.
The XG-20 had a design maximum T/O weight of 70,000 lb, but there was no tow aircraft available to pull this load, so it was restricted to 40,000 lb. After some gliding trials the XC-20 was modified to become the first American jet-powered transport aircraft, when fitted with two B-47 inboard engine pods containing four General Electric J47 turbojets. It flew in this configuration for the first time on April 21, 1951 as the XC-123A. Thus this design became the first to fly as a glider, a piston-powered aircraft and a jet transport.
The other prototype, the XC-123, powered by two 2,500 hp Pratt & Whitney R-2800-52W Double Wasp engine, proved successful, so the USAF issued a contract for 300 C-123B Provider transports. Chase did not have the facilities for large-scale production, the Kaiser-Fraser Corp. received the contract. This contract was withdrawn due to commitment problems, so finally the contract was awarded to Fairchild and a total of 303 were build, the first flew September 1, 1954. Service operations started in July 1955; 6 were exported to Saudi Arabia and 18 to Venezuela.
Numerous changes were made in the design during production, this included a large dorsal fin, redesigned rudder and elevator, paratroop doors, etc. The Thunderbirds used a C-123B (54-0671) as a support aircraft.
An attempt to improve performance was the addition of two 1,000 lb (454 kg) s.t. Fairchild J44 jet engine in the wingtips of the first C-123B. This resulted in the modification of ten production aircraft to C-123J. Another modification was the fitting of a wider tread main gear, the small number of aircraft modified so were known as C-123H's.
When the C-123B was send to the Southeast Asia war-theatre the aircraft finally came into its own, flying the assault transport mission it was designed for, operating from hastily constructed strips. The UC-123B was used to spread defoliant over forests thought to give cover to the Vietcong.
The prototype YC-123H was fitted with two 2,850 lb (1,293 kg) s.t. General Electric CJ610 jet engines mounted in pods slung from the wing and flown on 30 July 1962. Tested in South Vietnam for counter-insurgency operations this configuration proved successful and from 1964 on 183 more C-123B were fitted with J85-GE-17 (military counterpart of the CJ610) as auxiliary power. Designated C-123K these were extensively used for airlift missions. Some were further converted to AC-123K "Spectre" gunship.
The successor to Chase Aircraft, Stroukoff Aircraft, obtained contracts for Boundary Layer Control on the XC-123D (52-1627), flown in December 1954. This same aircraft being converted again into the YC-134 for the "Pantobase" project with retractable hydro-skis and flotation pontoon under each wing.
XG-20 converted to jet-powered prototype
wider tread main gear
two jet engine in the wingtips
two jet engine in pods slung under the wing
boundary layer experiment
Max T/O weight:
Jet cargo transport aircraft
Four 5,200 lb (2,359 kg) s.t. General Electric J47-GE-11 turbojets
110 ft (33.53 m)
77 ft 2 in (23.52 m)
32 ft 8 in (9.96 m)
1,223 sq.ft (113.62 sq.m)
25,000 lb (11,340 kg)
54,000 lb (24,494 kg)
400 mph (644 km/h)
2,500 mls (4,023 km)