High-speed plans

Despite the financial crisis that has also affected aerospace industry all over the world, the Russian Helicopters holding company, a recent merger of the country’s rotorcraft manufacturers, plans to enter the market with a new product – a high-speed helicopter within a decade. The company first revealed its high-speed concept in 2007, but at the HeliRussia 2009 exhibition, which took place in Moscow in May, Russian Helicopters displayed two high-speed helicopter concepts: the Mil Mi-X1 and the Kamov Ka-92, and released preliminary performance data for their designs. "The work is going on," says Andrey Shibitov, head of Russian Helicopters. "This year we finalized the requirements for the [high-speed] program and defined the problems that should be solved before the development starts."
The program includes simultaneous development of two designs – the Mil Mi-X1 and the Kamov Ka-92. The Mi-X1 is designed to have a take-off weight of just 10 tons, seat 25 passengers and fly to 1,500 km. The helicopter’s single main rotor means that in order to travel at high speeds it will have to overcome the retreating blade stall (RBS). This phenomenon occurs at airspeeds of some 300 km/h, and leads to vibrations that may ultimately destroy the rotor. Mil’s solution to fighting the onset of the RBS is to offload the rotor with the help of the proprietary Stall Local Elimination System (SLES). According to Mil Chief Designer Nikolay Pavlenko, the designers have already agreed to test SLES at Russia’s TsAGI Central Aerohydrodynamics Institute.
Earlier the manufacturer asserted that using SLES alone would give the Mi-X1 a speed of 450–500 km/h. According to the updated information made public at HeliRussia 2009, the helicopter will have a cruise speed of 475 km/h and a dash speed of 495 to 520 km/h. This will be possible through the use of a pusher propeller and a number of aerodynamic improvements, including a retractable landing gear and streamlined forward and rear fuselage sections. The Mi-X1 might be powered by two uprated Klimov VK-2500 turboshafts. Similar engines are installed on Mi-28N and Ka-52 attack helicopters.
The pusher propeller will also be used on the Kamov Ka-92 helicopter. As Kamov Chief Designer Sergey Mikheev explained, the traditional design when the main rotor both lifts and pushes the aircraft forward only works up to a speed of about 300 km/h. "Now we plan to split the functions of horizontal and vertical flights between different rotors," said Mikheev. The Ka-92 is planned as a 30-seat passenger helicopter with a take-off weight of 16 tons. It will feature Kamov’s signature coaxial main rotor. According to Mikheev, the first prototype will be powered by two reliable VK-2500 engines equipped with a new gearbox. But the designers plan to install more powerful 3,200 hp VK-3000 turboshafts as soon as St Petersburg-based Klimov Company finishes their development. Thanks to improved aerodynamics and a rear-mounted pusher propeller, the Ka-92 will have a cruise speed of 420 to 430 km/h.
Russian designers believe that the combination of VTOL capability, a cruise speed approaching that of fixed-wing regional aircraft, and a range of 1,500 km will make the high-speed helicopters an ideal transport for remote regions in Russia’s Siberia and the Far East.
By the end of 2009-2010 Russian Helicopters plans to select one of the two designs for further development. According to Andrey Shibitov, the first Russian high-speed helicopter is expected to take off in seven to 10 years if the government will finance the development. The company hasn’t applied for budget subsidies yet, but it already confesses it hasn’t enough financial re-sources to create a high-speed helicopter on its own.