The Much Maligned C-133 Cargomaster

In 1956 Douglas Aircraft debuted their new "do-all" transport plane. The C-133 Cargomaster. With its shiny new turbine engines it was a radical departure from the old radial engine C-54s and C-124s. It was big and long and could carry anything from an Atlas missile to artillery pieces. If you could squeeze the door shut, you could fly. All was right with the universe...until.

Looking like a stretched C-130 the plane had what at first seems to be a common cargo plane layout, but that is when looked at with modern eyes. It was the first straight tail plane to have aft clamshell doors that sat low to the ground so that cargo could easily roll on/off. The wings are actually above the fuselage and the main landing gears are in pods on the outside of it making the entire body of the plane a void space (critical for moving the ICBMs of the era). The turbine engines let it fly in pressurized comfort above much of the weather and at much improved speeds. So what was the problem with Douglas's new gem?

Unlike most new planes there was no prototype phase for this plane. There was some test flying but essentially to speed up deliveries the USAF took them right off the drawing board. To get the plane light enough designers used thinner gauge aluminum. The only turbine engine available had to run at a constant speed which meant prop controllers were constantly moving to keep up with power demands. The plane was around less than two years when the first one crashed.

It would later be learned that the plane stalled with no warning, the tail could get blanked out by the airflow. One wing stalled before the other resulting in a violent roll. A simple stall strip solved the problem. Also, it could ice up and stall and in one case (the last crash) the thin aluminum gave up the fight and there was a decompression. Some were lost mid ocean with no ability to research the cause. Metal fatigue, stall and prop/engine failure are the usual suspects.

Despite impressive load hauling abilities, many people were scared to fly in them. The accident rate was higher than the C-130, but the Hercules could not carry the same payloads. The plane was retired in 1971 after 10 of the 50 built had crashed. One continued to operate in Alaska until 2008 and the crew stand by it. It is arguable that a normal prototype phase may have uncovered some of the mysteries that claimed the lives of 61 men.

The Smithsonian Air & Space magazine just published a wonderfully detailed article in the Sept. 2010 issue.