Although most information about the PAK FA is classified, sources within in the Russian Air Force and Defense Ministry have openly stated that it will feature stealth technology and have the capability to supercruise, and incorporate advanced avionics such as an Active Electronically Scanned Array (AESA) radar and an artificial intelligence system. It is to be outfitted with the next generation of air-to-air, air-to-surface, and air-to-ship missiles.
Composites are used extensively on the T-50 and comprise 25% of its weight and almost 70% of the outer surface. It is estimated that titanium alloy content of the fuselage is 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 between 4.9-5.1 m long. The main bays are augmented by bulged, triangular-section bays at the wing root.
The Moskovsky Komsomolets reported that the T-50 has been designed to be more maneuverable than the F-22 Raptor, at the cost of making it less stealthy than the F-22. One of the design elements that have such an effect is the Leading Edge Vortex Controller (LEVCON).
The PAK FA does not have the very low observable stealth of the F-22, but instead uses composite materials, aerodynamic configuration, and engine signature reduction measures to achieve low levels of radar, optic and infrared signatures. Carlo Kopp has said that once the PAK FA is fully developed into a stealthy design, it should be a rough match for the F-35 in low observability, but aerodynamically superior
