PAK FA, Sukhoi


Sukhoi PAK-FA T-50 Photo from paralay.com

The Sukhoi PAK FA is a fifth generation stealthy fighter aircraft being developed by Sukhoi OKB for the Russian Air Force. The PAK FA when fully developed is intended to replace the MiG-29 Fulcrum and SU-27 Flanker in the Russian inventory and serve as the basis of the Sukhoi/HAL FGFA project (being developed with India). As a 5th generation jet fighter, it is designed to directly compete with the American F-22 Raptor and American/British F-35 Lightning II.

The current prototype, called T-50, performed it's first flight on 29th of January 2010. It was flown by Sukhoi test-pilot Sergey Bogdan and lasted for 47 minutes. It's second flight took place on 6th of February. As of August 2010, it had made 17 flights and by mid November 2010, 40 in total.

In the late 1980s, the Soviet Union outlined the need for a next-generation aircraft to replace the MiG-29 and Su-27 in frontline service. Two projects were proposed to meet this need, the Sukhoi SU-47 and the Mikoyan Project 1.44. In 2002, Sukhoi was chosen to lead the design for the new combat aircraft. The PAK-FA will incorporate technology from both the Su-47 and the MiG 1.44.

Type: PAK-FA / T-50
Country: Soviet Union / Russia
Function: fighter
Year: 2010 (first flight)
Crew: 1
Engines: 2 * 175 kN NPO Saturn
Wing Span: 14.20 m
Wing area: 78.8 m2
Length: 19.80 m
Height: 6.05 m
Empty weight: 18500 kg
Loaded weight: 26000 kg
Maximum Fuel weight: 10300 kg
Max. takeoff Weight: 37000 kg
Wing loading: 330 kg/m2 (normal) - 470 kg/m2 (max)
Thrust/weight: 1.19
Maximum g-load: +10.0 g
Cruise Speed: 1300-1800 km/h
Max Speed: 2600 km/h (Mach 2.45 @ 17000m)
Rate of climb: 350 m/s
Ceiling: 20000 m
Ferry range: 4000-5500 km
Armament: 1*30 mm GSh-30-1 cannon, 10 internal,6 external hardpoints for R-74M Archer and R-77M Adder missiles. Total payload 7500 kg.



Design

Although most of information about the PAK FA is classified, it is believed from interviews with people in the Russian Air Force and defense ministry that it will be stealthy (on the level slightly under that of the F-117), have the ability to supercruise, be outfitted with the next generation of air-to-air, air-to-surface, and air-to-ship missiles, incorporate an AESA radar with a 1500-element array and will have "artificial intellect".

The PAK FA was expected to use a pair of Saturn 117S engines on its first flights. The 117S (AL-41F1A) is a major upgrade of the AL-31F based on the AL-41F intended to power the Su-35BM, producing 142 kN of thrust with afterburner and 86.3 kN dry. In fact, PAK-FA already used a completely new engine in its first flight, as stated by NPO Saturn. The engine is not based on the Saturn 117S. The engine generates more thrust and a complex automation system, to facilitate flight modes such as maneuverability. It is expected that each engine will be able to independently vector its thrust upwards, downward or side to side. Vectoring one engine up with the other one down can produce a twisting force. Therefore the PAK FA would be the first fifth generation fighter with full 3-D thrust vectoring along all three aircraft axes: pitch, yaw and roll. These engines will incorporate infrared and RCS reduction measures.

The first flight video shows that PAK-FA/T-50 has no conventional rudders, its vertical tails are fully movable. This special tail fin design is mechanically similar to V-tails used by the Northrop YF-23 in 1990s, but is supplemented by dedicated horizontal stabilators (as on the F-22). The T-50 has wing leading-edge devices above the jet engine intakes that have been called a challenge for signature control.

Composites are used extensively on the T-50 and comprise 25% of its weight and just under 70% of the outer surface. It's estimated that titanium alloy content of the fuselage is around 75%. Sukhoi's concern for minimizing radar cross-section (RCS) and drag is also shown by the provision of two tandem main weapons bays in the centre fuselage, between the engine nacelles. Each is estimated to be around 5m long. The main bays are augmented by bulged, triangular bays at the wing root.


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