The US military is turning to the realms of science fiction in a bid to invent a flying submarine, authorities said.
Designs for a submersible aircraft are wanted by the agency which commissions advanced research for the US Department of Defence (DoD).
The new machine, dubbed a three billion dollar (£1.9 billion) flying submarine by US media, needs to be capable of carrying eight men and their equipment a combination of 1,150 miles by air, 115 miles by sea, or 22 miles underwater – in less than eight hours.
The Defence Advanced Research Projects Agency (Darpa) said it was “interested in exploring radical new technologies that can provide a game-changing DoD capability for inserting small teams, clandestinely, along coastal locations”.
The submersible aircraft would need the speed and range of an aircraft, the “loiter capabilities” of a boat, and the “stealth of a submarine”.
“By combining the beneficial characteristics and the operating modes of each platform, Darpa hopes to develop a craft that will significantly enhance the United States’ tactical advantage in coastal insertion missions,” the agency’s briefing notes said.
Jan Walker, a Darpa spokeswoman, said: “We issued a call for research ideas for a submersible aircraft.
“We envision a platform that would spend the bulk of its time in the air and would only spend short periods of time submerged, and would operate submerged only at shallow depths.”
Previous attempts to come up with such a craft failed because “the design requirements for a submersible and an aircraft are diametrically opposed”.
A flying submarine called FS-1 became one of the most recognised elements of the 1960s TV series Voyage To The Bottom Of The Sea, but even that did not reach the specifications the US military is looking for now. It was yellow and only held a two-man crew, but was able to carry passengers.