The Douglas C-133 Cargomaster is an American large turboprop cargo aircraft built between 1956 and 1961 by the Douglas Aircraft Company for use with the United States Air Force. The C-133 was the USAF’s only production turboprop-powered strategic airlifter, entering service shortly after the Lockheed C-130 Hercules, which is designated as a tactical airlifter. It provided airlift services in a wide range of applications, being replaced by the C-5 Galaxy in the early 1970s.
The C-133 was designed to meet the requirements for the USAF’s Logistic Carrier Support System SS402L for a new strategic transport. The aircraft differed considerably from the C-74 Globemaster and C-124 Globemaster IIs that had preceded it. A high-mounted wing, external blister fairings on each side for the landing gear, and rear-loading and side-loading doors ensured that access to, and the volume of, the large cargo compartment were not compromised by these structures. The cargo compartment (90 ft/27 m in length and 12 ft/3.7 m high) was pressurized, heated, and ventilated.
The C-133 was for many years the only USAF aircraft capable of hauling very large or very heavy cargo. Despite the Douglas C-124 Globemaster II‘s capabilities, there was much cargo that it could not carry because of its configuration with a cargo deck 13 ft (4 m) off the ground and its lower, though substantial, engine power. The C-133 continued in service after the formation of the USAFs Military Airlift Command on 1 January 1966.
An air force, also known in some countries as an aerospace force or air army, is in the broadest sense, the national military branch that primarily conducts aerial warfare.