Major Work Ahead On T-50 Stealth Fighter

Russia has begun flying a stealthy fifth-generation fighter to rival the U.S. F-22, but Western analysts question whether Sukhoi can develop and deliver the aircraft by 2015 as promised.

Sukhoi’s T-50, which made its 47-min. first flight on Jan. 29 from the KnAAPO facility in Komsomolsk-on-Amur, is the prototype of the PAK FA “future front-line aircraft,” the first new-generation fighter for the Russian air force since the Su-27 Flanker entered service in 1984. India plans to co-fund development and co-produce the new aircraft.

The aircraft is clearly shaped for stealth, with the chined forward fuselage, planform edge alignment, internal weapons bays and small vertical tails. The T-50 shows resemblances to the F-22 Raptor, but also reflects its Su-27 heritage in the wide “centroplane” that blends the fuselage and wing.

Sukhoi says “the T-50 will demonstrate unprecedented small cross section in the radar, optical and infrared range owing to composites and innovative technologies applied in the fuselage, aerodynamics of the aircraft and decreased engine signature.”

U.S. analysts are impressed, but not yet panicked by the T-50. “Don’t go overboard and call it the Raptorski,” says a Washington-based official. “It is essentially a Flanker in the shape of a fifth-generation fighter at this point. It still needs supercruise engines, advanced radar and a lot more work before military planners can start saying how it’s going to compete with the F-22 or even the F-35.”

Work on the T-50 began in the early 2000s, and the fighter is somewhere between a technology demonstrator and a development aircraft. How much effort is needed to finalize the production aircraft is not clear. Sukhoi’s Su-27 was substantially redesigned from the T-10 prototype, which first flew in 1977; but despite some rough edges, the T-50 looks closer to a finished product.

The YF-22 prototype first flew in September 1990, and the first development aircraft in September 1997, but the F-22 was not declared operational until December 2005—a longer cycle time than proposed for the PAK FA. And there are only three prototypes: the T-50-0 static-test article; T-50-1, now flying; and T-50-2, which will be used for ground testing. The two YF-22s were followed by nine development F-22s.

U.S. defense analysts see a flying planform that incorporates low-observable attributes in edges and shaping that are notable for a prototype. But, they caution, the work needed to finish a stealth design is great. There is obvious use of composites in the T-50; but many areas are metal, and analysts are unclear whether this is just for the prototype, with plans for more composites in production aircraft.

Seemingly similar in size to the Su-27, which it will replace, the T-50 like the Flanker has widely separated engines. This makes the three-dimensional thrust vectoring effective in roll, as well as yaw and pitch, and provides room in the center fuselage for fore and aft weapons bays. There are side bays for short-range air-to-air missiles (AAMs) under the inboard wing sections. The centroplane also provides plenty of room for internal fuel. There are hardpoints for external stores under the inlets and wing.

Unusual design features include the small all-moving vertical stabilizers, made possible by thrust vectoring, and the movable wing leading-edge extensions. These act like foreplanes and provide the three-surface control afforded by the canard on the Su-30. The delta-wing planform, similar to the F-22’s and likewise coupled with powerful engines, will provide supercruise capability...................Aviation Week