A pod plane or Clip-Air is a type of airplane design where the payload carrying part can be detached from the rest of the aircraft. In this way the aircraft can have a much reduced loading and unloading time or change between different configurations of cargo or passenger capability.
The idea has been recently re-evaluated by the École Polytechnique Fédérale de Lausanne in Switzerland. The developers are planning to build a 10-meter prototype of a Clip-Air plane.
Detachable pod aircraft Wikipedia
In November 1950, the Fairchild XC-120 Packplane first flew. This was an experimental military transport for the U.S Air Force. Described as a futuristic "pod plane", it was a development of the C-119 Flying Boxcar. Although tested, the project was cancelled without any further production.
Pod planes have two main components: the flying component: airframe, cockpit and engines; and the capsules: detachable pods (cabin or cargo hold). The flying component and the individual capsules can be detached from each other and combined in different ways.