In 1934 Boris Petrovich Ushakov, a student engineer at a Soviet military academy, devised a flying underwater boat - a three-engined floatplane designed to scout out enemy ships and then ambush them. Ushakov envisaged his craft flying ahead of the target, landing on the sea and then flooding its fuselage so that it could lie in wait beneath the surface and torpedo the ships as they sailed past. Ushakov submitted his radical design, which included... a conning tower and periscope, to senior officers in 1936. But the concept was never put into practice, being deemed too heavy to be effective. It took another three decades before a flying sub was constructed. This was a craft built in 1962 by Donald Reid, an engineer at the aircraft manufacturer North American Aviation. The Reid Flying Submarine (RFS-1) was a true mongrel, constructed by Reid in his spare time using leftover parts from other aircraft and, like Ushakov's design, it was a floatplane. The craft proved able to dive to a depth of a few meters in tests, but was so heavy it could only make short hops into the air. Though this was at the height of the Cold War, the U.S. Navy showed little interest in Reid's machine. The difficulty with the submersible seaplane is that aircraft must be light to minimize the power needed to get airborne, while subs need massive hulls to resist crushing. Funding for this concept was discontinued in 1965.