Nowadays, stealth fighters – F-22, F-35, J-20 and PAK FA – are often being compared to each other and to other, non-stealth fighter aircraft. While these comparisons make sense, exposing certain advantages and disadvantages, they typically ignore one crucial detail. All stealth fighters are designed for one, or a narrow range, of highly specific missions. F-22 was designed for air combat deep inside the Soviet-era IADS, intercepting enemy fighters while they were still heavy with unspent fuel and missiles and possibly gaining altitude after takeoff. As a consequence, it was designed with emphasis on supercruise and all-aspect stealth. F-35 is a result of USAF / US Navy’s requirement for first-day-of-the-war stealth bomber, intended to degrade IADS before nonstealthy strike aircraft and equally nonstealthy escort fighters move in to carry out their missions; consequently, frontal stealth, in-built targeting pod and MAWS were given emphasis while supercruise and maneuverability were more-or-less ignored. J-20 is designed to take out US AWACS aircraft, which would be a major blow in the war due to USAFs excessive reliance on the same, especially in beyond visual range combat (as USAF has so far ignored importance of BVR VID capable sensors, such as IRST); as a result it has high cruise speed and altitude but comparably less maneuverability. J-31 is an F-35 copy, designed for same missions but without problematic STOVL requirement. PAK FA is designed for both air combat and strike missions deep inside the enemy IADS, but it sacrifices rear-quarter stealth and relies instead on significant supercruise capability to keep it safe from rear-quarter threats. Outside of these missions stealth fighters are seriously disadvantaged by difficult maintenance, larger than average visual signature, IR signature and fuel consumption, limited weapons loadouts and requirement for strict EMCON (last one applies to all fighter aircraft, but significantly more so to stealth fighters where even one communications or IFF burst can give away its position).
Despite all that, stealth fighters have had more and more requirements pushed onto them. F-22 is typically assumed today to be general-purpose air superiority fighter, similar to the F-15; and it indeed may have to take on that role, with F-15s and F-16s growing older, F-35 being incapable of serious air-to-air combat and no other fighter being avaliable to fill in the role. Due to aging legacy fighters with no non-stealth replacement (excepting the F-18E Super Hornet, which is equally incapable of air-to-air combat) and limited number of F-22 airframes avaliable, F-35 has seen itself turn into allegedly “multirole” fighter, with air superiority role being pushed onto it but with no corresponding change in designed capabilities to compensate for it. PAK FA, J-20 and J-31 seem to have kept within their designed missions, being intended to serve alongside nonstealthy fighters instead of replacing them. While that might change due to influences of aerospace industry on defense politics, this influence is likely weaker in Russia and China than it is in United States. In either case, this requirements creep has forced the aerospace industry and militaries to engage in extensive fact-warping campaign, which they may have started to believe themselves.