But the Ria Novosti newswire reports Konstantin Sivkov, who is identified as the "first deputy head of the Russian Academy of Geopolitical Problems", filled in some criteria: Invisible to radar, extended flying range, smart weapons, air-to-air capability and 310-370mph speed.
Sivkov also noted the "US recently began working on a similar project". I'm not sure exactly what he's referring to. The US Army is considering launching the Joint Multi-Role (JMR) program, but the requirements are not set yet. Sivkov may be referring to the Sikorsky X2 or Boeing DiscRotor.
Ria Novosti also quotes Sivkov's boss, Leonid Ivashov, explaining the aircraft could fly within five years if it receives substantial investment, or "may drag on for 20-30 years" otherwise.
Update: Flightglobal first reported about this story two years ago at the Farnborough Air Show:
The Mi-X1 is an advanced conceptual project that is looking to increase the speed of its helicopters from 300kmh up to more than 500kmh. The company says it is also looking to engineer increased flight range of up to 1,500km in order to service offshore oil-platforms or other distant or difficult-to-reach locations. Mi-X1 is a civilian export product, though a lightweight military model is likely to be produced for the Russian armed forces.
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