Russia plans to challenge the West in high-speed helicopter market

 - July 28, 2009, 6:12 AM

Russian manufacturers Kamov and Mil are developing advanced high-speed helicopter (AHSH) designs with the goal of creating a helicopter that flies as fast as
a turboprop airplane. Western companies have exhibited similar interest, with Sikorsky developing the X2 technology demonstrator, Bell and Agusta partnering on the BA609 tiltrotor and Eurocopter said to be studying a high-speed helicopter concept. At the HeliRussia international helicopter exhibition in May Vertolyoty Rossii (Russian Helicopters) displayed AHSH mockups from Kamov and Mil.

Kamov’s model, the 30-seat Ka-92, would have a takeoff weight of about 16 metric tons (35,000 pounds). It employs the company’s traditional coaxial main rotor and is powered by two 3,200-shp Klimov VK-3000 turbo-shaft engines. An improved aerodynamic outline and the tail pusher would give the Ka-92 a maximum speed of an estimated 248 knots and a cruise speed of 227 knots. Kamov believes that the combination of VTOL capability, a cruise speed approaching that of fixed-wing regional aircraft and a range of 756 nm would make the Ka-92 an ideal transport for Siberia and the Far East.

Mil’s contender, the 25-seat Mi-X1, will be smaller than the Ka-92, although still a large helicopter. It would be designed to have a takeoff weight of 10 to 11 metric tons (22,000 to 24,000 pounds). The Mi-X1 could be powered by two 2,400-shp Klimov VK-2500 engines. Similar engines are installed on the Mi-28N and Ka-52 attack helicopters.

Because the Mi-X1 would have a single main rotor, it would need to overcome retreating blade stall to travel at high speeds. This phenomenon occurs at about 160 knots forward airspeed and leads to vibrations that may ultimately destroy the rotor. Mil’s solution is to offload the rotor with the help of the proprietary stall local elimination system (SLES).

The manufacturer has previously said that using SLES alone would give the
Mi-X1 a speed of between 242 and 270 knots. At Heli-Russia, officials said that with a pusher prop and a number of aerodynamic improvements, including a retractable landing gear and streamlined forward and rear fuselage sections, the helicopter could have an estimated cruise speed of 256 knots and a dash speed of 280 knots.

“The high-speed helicopter will incorporate a mix of scientific, engineering and technological solutions that will dramatically change the concept of the rotary-wing aircraft,” Sergey Mikheyev, Kamov general designer, told AIN. “It will have essentially new control systems and a specially designed main rotor. The substantially enhanced speed and resultant range will change the role of helicopters and their niche in the market.”

Mikheyev said that one of the main difficulties the AHSH project faces is the manufacture of a lifting rotor for operation in demanding flight conditions at high speeds. “Of course, the blades will be made from new-generation carbon plastics with the help of nanotechnologies. However, thus far we’ve made only the first steps,” he said.

The Russian government plans to select a single AHSH design from the Kamov and Mil proposals. Andrei Shibitov, director general of Vertolyoty Rossii/Russian Helicopters, said production of the selected design would start by early next year. With support from the government, the Russian high-speed helicopter would take to the air within seven to 10 years, he claimed.

Said Mikheyev of Kamov, “Russia must create the high-speed helicopter in order
to retain its leadership in the world’s helicopter engineering.”