At the moment, the Defense Advanced Research Projects Agency (DARPA) is not close to constructing any test planes and is merely exploring the possibility on paper, officials and experts said. Story highlights Pentagon wants aerial platform to carry drones 
 
 Defense Advanced Research Products Agency is seeking proposals 
 
 Pentagon wants to use existing aircraft to launch and recover drones 
 
 (CNN) Got an idea on how to make a flying aircraft carrier?
– In the latest effort to make reality out of what is currently science fiction, US officials are looking into the possibility of building a mothership: a large aircraft from which smaller ones take off. "This is the float-the-idea stage of the concept. It's not the build-me-a-prototype stage," says an expert. But this month, the Pentagon asked companies to envision designs for a drone-carrying cargo plane, AFP reports. The request seeks a design that could be demonstrated within four years, CNN reports. The effort has focused on converting aircraft the Pentagon already has. "One promising idea is enabling existing large aircraft, with minimal modification, to become 'aircraft carriers in the sky,'" says an official with the Defense Advanced Research Projects Agency. Versions of the idea have been around since the 1920s; in the 1930s, airships carrying Sparrowhawk biplanes crashed and the US dropped the effort for the time being. An underwater version of such a system could come sooner than a flying version, AFP notes: The US has already managed to launch a drone from a submarine's missile tube.