The greatest advantage to 5th Generation fighters is supposed be stealth, the appearance of newer detection systems and more advanced radars will require a new super stealthy aircraft shape to counter counter stealth; a much smaller Radar cross section than on current stealth aircraft like the F-22 Raptor, B-2 Spirit, and unsuccessful designs like the YF-23 Black Widow II will be also needed. A new generation of engines allowning ultra high altitude flight and supercruise speed a lot faster than on current fighters, as well as a new generation of armament like directed energy weapons to attack enemies with the speed of light, are planned to be included.
Their avionics are supposed to feature next generation electronic attack, passive detection, integrated self-protection and cyber attack capabilities.
In summing up sixth gen fighters are expected to outperform current 5th Gen fighters in terms of speed, range, stealth, self-healing structures and to provide the same "technological leap" against modern 5th Gen fighters, as employed by the F-22 Raptor against Soviet 4th Gen fighters like the Su-27 or MiG-29 in the 1990's.