Experiments in container shipping

The Fairchild XC-120 'Pack Plane" was an experimental aircraft with a detachable wheeled cargo pod as the lower fuselage, making cargo loading and unloading quicker and more convenient.  The plane could fly with or without the pod and the landing gear collapsed scissor-like to drop the pod on the ground. One prototype was built and it made many airshow appearances in the early 1950s. The idea never caught on and the plane was eventually  scrapped.
 The removable pod idea never went away and reappeared with the Sikorsky Skycrane.