The Douglas C-133 Cargomaster was a large Unite States cargo aircraft built by the Douglas Aircraft Company between 1956 and 1961; 50 aircraft (32 C-133A and 18 C-133B) were constructed and put into service with the USAF. A single C-133A and a C-133B were built and kept at Douglas Long Beach as "test articles." They had no construction numbers or USAF tail numbers.