Mil Mi-X1

The Mil Mi-X1 is a proposed high-speed compound helicopter that Mil put forward to a Russian government competition against the Kamov Ka-92 for a rotorcraft cruising at about 400 kilometres per hour. It uses one main rotor with a rear-mounted pusher propeller for extra speed and torque control, two VK-2500 engines, a weight of about 10,000 kilograms normal and 12,000 maximum, and a cabin for 20 to 25 passengers or 3,500 to 4,000 kilograms of cargo. A system called SLES, which delays stall on the retreating blade, was meant to allow a cruise speed of 257 knots and a top speed of 280 knots. The Russian defence ministry chose the Mil proposal over the Kamov one in early 2018, and the two bureaux were to merge into a National Helicopter Center. It remains a design project.