Kamov, which has been the leading producer of coaxial rotor helicopters for decades, is proposing an advanced helicopter that bears a strong similarity to the Sikorski advancing blade helicopter.

What is notable is that the two rotors are further apart than those of the S-79, it has wings, (and canards) and the propulsor is a turbofan rather than a propeller.

First, it’s pretty clear from this that the rotors are probably not as stiff,  and that the controls are less sophisticated, requiring more space between the two rotor disks to avoid the blades striking each other.

The wings, and the turbofan propulsion, imply that it is designed for a much higher speed, probably at the expense of range, noise, and low speed accelleration

That being said, I am profoundly dubious of their claim of a top speed of 700 km/h (440 mph/370 kts) for any rotorcraft:

Pictures of a Kamov design for an advanced attack helicopter have appeared on a Russian website.

The images appear to have been leaked amid competition between the Kamov and Mil Moscow Helicopter design bureaus within Russian Helicopters to develop the country’s future high-speed combat helicopter, called SBV.

Russian Helicopters announced at the Army 2017 forum in Moscow last September that it had signed a two-year contract with the Russian defense ministry to refine concepts for a high-speed attack helicopter, with both Kamov and Mil working on designs.

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The leaked photographs show Kamov General Designer Sergei Mikheyev presenting the bureau’s concept, a winged coaxial-rotor, twin-turbofan compound helicopter reportedly capable of up to 700 kph (380 kt.) This compares with a speed of more than 400 kph claimed for Mil’s single-main-rotor design.

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Propulsion is provided by what appear to be a pair of turbofans mounted in the aft fuselage and driving the rotor gearbox via a pair of shafts that project forward from the engines—an arrangement reminiscent of the shaft-driven lift fan in the Lockheed Martin F-35B.

The engines likely direct most of their power forward to shaft-drive the rotors for takeoff, hover and low-speed maneuvers, then shift more of the power to thrust as forward speed increases. The rotor system has a pair of contra-rotating three-blade rotors with swept tips.