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AL-41 engine problems are over, says Lyulka Saturn

Alexander Velovich/MOSCOW

MIKOYAN'S FIFTH-generation fighter, the Article 1.42, has been fitted with Lyulka Saturn AL-41 next-generation engines, with the engine-design bureau claiming that previous engine problems have been overcome.

Victor Chepkin, Lyulka Saturn president and chief executive, says that the AL-41s installed in the Mikoyan technology demonstrator, shown in June to Russian defence minister Gen. Pavel Grachev, are development engines rather than experimental.

He adds that, as installed on the aircraft, these include circular thrust-vectoring nozzles. Circular- and box-nozzle thrust-vectoring configurations are thought to have been examined.

The 1.42's first flight has been delayed repeatedly, with Mikoyan saying that this was partly the result of problems with the power plant.

Chepkin claims that AL-41 performance "... is in no way inferior to the Pratt & Whitney F-119 engine powering the F-22". The AL-41 is a fifth-generation engine distinguished in principle by "...absolutely new aerodynamics, ie all compressors and turbines were designed and developed exclusively using a three-dimensional computer model," he explains.

The design also includes advanced materials, including high load-bearing titanium alloys and compacted heat resistant powder alloys for discs, shafts and load-bearing body parts.

Chepkin says that a qualitatively new level of turbine-inlet temperature has been attained in the AL-41 design adding 250°C to the value achieved in the Lyulka AL-31, now powering the Sukhoi Su-27/Su-33, which required a new level of technology for blade cooling.

The high inlet temperature is necessary to allow the aircraft to "super cruise" -that is, to cruise supersonically without using reheat. The AL-41 has already logged a "sufficiently high number of hours" in flying testbeds.

Specification figures for thrust, specific fuel consumption and acceleration time have been met, according to Chepkin, but the turbofan has a limited guaranteed life.