The Douglas C-133 Cargomaster was the largest turboprop transport to be built for the USAF, and was designed to carry ICBM missiles around the United States.
The C-133 was designed in response to USAF Logistic Carrier Supporting Systems SS402L, for a large transport capable of carrying missiles. Work on the project began in February 1953 and the first aircraft was completed in 1956.
The C-133 was a high wing aircraft, with long tapered wings with slight dihedral. The fuselage had a circular cross section, and the crew cabin was carried in the rounded nose. It was powered by four Pratt & Whitney T34-P-3 turbo-props, carried under the wings. The main landing gear was carried in pods mounted on the sides of the fuselage below the wings, and there was also a nose wheel. It had a 13,000cubic foot cargo space that was pressurised to 10,000ft and could maintain that pressure at up to 35,000ft. It could carry the Atlas missile, sixteen loaded jeeps or two 40,000lb prime movers. There were loading ramps at the rear of the cargo cabin, allowing the heavy cargos to be driven straight in.
The first C-133A made its maiden flight on 23 April 1956. Deliveries of the production aircraft began in August 1957 and 45 were built between then and 1961.
A total of 50 aircraft were built by 1961. The first 35 were completed as the C-133A. During its production run a series of changes were made. The tail was redesigned from the eighth aircraft. Late production aircraft got 7,100 eshp T34-P-7W turbo-props. The last three had a new clamshell rear loading door which added 3ft of useable space and allowed fully assembled Atlas ICBMs or Thor and Jupiter IRBMs to be carried.
The last fifteen aircraft were completed as the C-133B. These could carry 52,000lb of cargo, up by 10,000lb on the original C-133A. These were powered by 7,500 eshp T34-P-9W turboprops and had the clamshell loading door. Production was completed in April 1961.
In 1958 the C-133 set a lift record when it carried 117,000lb to 10,000ft, beating the previous record at that altitude by 40,000lb. The C-133 remained in service for ten years, but both versions had to be withdraw in 1971 because of problems with metal fatigue.
Engines: Four Pratt & Whitney T-34 turboprops
Power: 5,600lb thrust each
Crew: 4 to 9 (pilot, co-pilot, flight engineer, navigator, loadmaster and relief crew)
Wing span: 179ft 8in
Length: 157ft 8in
Height: 47ft 2in
Empty weight: 110,000lb
Maximum weight: 286,000lb
Maximum speed: 359mph at 8,700ft
Cruising speed: 310mph
Service ceiling: 32,000ft
Normal range: 2,200 miles with 90,000lb payload, 4,000 miles with 52,000lb payload
Maximum payload: 133,000lb/ 200 troops