The Douglas design that influenced all the rest…
On April 23rd 1956 the Douglas C-133 Cargomaster flew for the first time. The forgotten link between the war-built and designed transports and the airlifters that replaced it, the Cargomaster was the first American strategic transport to be designed for direct loading from ground level and the first and largest to be powered by turboshaft engines. Also unique in that it combined a high-mounted wing with faired fuselage-mounted retractable landing gear, the C-133 was the template followed by the vast majority of the airlifters designed and built after it; not just in the United Sates, but around the world. And it sounded really awesome…more like a B-36 Peacemaker than anything else before or since. If you ever heard one in flight you know.
Designed to be a strategic airlifter as opposed to a tactical airlifter such as the Lockheed C-130 Hercules, the Cargomaster had a 97 foot long cargo compartment that was more than 13 feet high, pressurized, heated, and ventilated. The C-133A and C-133B differed primarily in the configuration of the rear cargo doors. The B model Cargomaster had rear cargo doors that opened to the side, allowing it to carry outsize cargo like the SM-65 Atlas, LGM-25 Titan, and LGM-30 Minuteman series of ballistic missiles. C-133s delivered these missiles by the hundreds to their bases. They also delivered them to Cape Canaveral for use as spacecraft boosters. Eventually all Cargomasters were reworked to make them capable of carrying these strategic loads.
Douglas never did build a prototype Cargomaster. The airlifter went straight into production off the drawing board. The first to be built were 35 C-133As which were delivered the United States Air Force (USAF) Military Air Transport Service (MATS) beginning in August of 1957. These 25 C-133As were followed by 15 C-133Bs. Soon Cargomasters were flying MATS cargo flights all over the world. On their inaugural flights from the United States to bases in Europe two C-133As established transatlantic speed records for transport aircraft. When MATS became Military Airlift Command (MAC) in 1966, the Cargomasters just kept on doing what they did best.
The Cargomasters proved to be especially versatile and valuable during the Vietnam War, responsible for carrying the largest airliftable components and vehicles back and forth between Southeast Asia and America. In simplest terms, if it wouldn’t fit in a Lockheed C-141 Starlifter, then it would probably fit into a Cargomaster. The C-133’s cargo area was 27 feet longer, four feet higher, and nearly two feet wider than that of the C-141. If it was too big (or too heavy) for the Cargomaster then it was shipped in pieces or went to the war zone on a boat instead.
Powered by four Pratt & Whitney T-34 turboshaft engines turning 18 foot three-bladed propellers, a distinctive feature of the C-133A was the sound it made in flight. The thrust of the engines was controlled by propeller blade pitch alone- the engines were constant-speed. This arrangement was every bit as complicated as it sounds and malfunctions caused several operational losses. The C-133B had uprated T-34s that produced a combined 4,000 more shaft horsepower, but it sounded and operated the same. The airlifter cruised at a shade more than 320 miles per hour and was capable of lifting 55 tons of cargo. The cargo hold load height was the same five feet off the ground as the airlifters that eventually replaced it.
And into that cargo hold went the darnedest things. For instance, the C-133 could carry one Boeing Vertol CH-47 Chinook helicopter, One Sikorsky CH-54 Skycrane helicopter, two Sikorsky HH-3 Jolly Green Giant helicopters, five UH-1 Iroquois (Huey) helicopters, four Cessna O-1 Bird Dog aircraft, or one McDonnell Douglas F-4 Phantom II. The aforementioned ballistic missiles could all be carried along with PGM-17 Thor, SM-62 Snark, or AGM-28 Hound Dog tactical missiles. C-133s could also carry 11 standard pallets of general cargo.
Throughout their service lives the C-133s visited every corner of the planet and usually brought something nestled inside. In October of 1961 a C-133 delivered three pieces of snow equipment to McMurdo Sound in Antarctica. In December of 1961 a C-133 brought John Glenn’s Atlas 6 booster for his Mercury spaceflight in Friendship 7. Later in 1963 the first Project Gemini booster was delivered by a C-133. LGM-30 Minuteman missiles rode aboard Cargomasters to bases such as Malmstrom Air Force Base (AFB) in Montana, Ellsworth AFB in South Dakota, and Minot AFB in North Dakota beginning in 1962.
In December of 1963, the first C-133 flight to New Zealand delivered a propeller shaft and propeller to the Navy icebreaker USS Atka (AGB-3) docked at Wellington. A C-133 airlifted a new propeller for the aircraft carrier USS Coral Sea (CVA-43) all the way to Japan in 1966. In August of 1967 a Cargomaster delivered an entire diesel engine (weighing 34,000 pounds) for a submarine to Japan. A C-133 flew from Quonset Point NAS in Rhode Island to McMurdo Sound carrying two Huey helicopters during October of 1970.
C-133s also supported operations with exotic-sounding names like Check Mate II, Long Thrust IIA, New Tape, Tip Top, Back Porch, Three Pairs, Tidal Wave, Indian River, Fig Hill, Combat Fox, Eagle Thrust, and Acid Test. C-133s even flew the Apollo command modules back from Naval Air Stations to NASA facilities after their returns to earth.
Production of the C-133 ended in 1961 after only 50 airframes had been built. Lockheed had wowed the Air Force brass with the C-5A Galaxy, which could out-perform and out-haul the C-133 (and every other airlifter at the time). Of course with only 50 airframes available every C-133 was worked hard. By the time they had been in service for only about 15 years many of them were just plain worn out and developing stress fractures and corrosion. Originally designed and built for a service life of 10,000 flight hours, the majority of the fleet had been extended to near twice that. The Air Force knew the value of the Cargomasters and kept as many of them in service as possible until they were replaced by the Galaxies in the early 1970s.
Take a good analytical look at the airlifters flying the friendly skies today. The age-old warrior Lockheed C-130 Hercules; The Lockheed C-141 Starlifter and C-5 Galaxy; The Boeing C-17 Globemaster III; The Airbus A-400M; The Ilyushin Il-76; The Kawasaki C-1 and C-2; The Alenia C-27J Spartan; The Antonov An-124 Ruslan and An-225 Mirya; the Grumman C-1 Greyhound. Even the Bell-Boeing MV-22 Osprey. Every one of these airlifters, and many more, owe their basic fuselage design principles and cargo loading ability to the same predecessors: The Lockheed C-130 Hercules. And the Douglas C-133 Cargomaster. Enjoy the sight (and that sound) of the last flight of the Douglas Cargomaster!