The first sixth generation fighter remains a long way off, and at this point, much of the talk about them remains pure guesswork, far too much of it wish lists of improvement in familiar areas of performance (like greater stealth or connectivity) unconnected with a technical basis for such improvements, or the realization of science fiction-al concepts (like hypersonic, laser cannon-firing invisible jets). Still, it is worth noting that virtually all of the features regarded as standard on the fifth-generation fighter, after all, actually appeared in earlier aircraft, if in a less sophisticated form: stealth (in the F-117 and B-2); super-cruising capability (seen in the British Lightning interceptor); thrust-vectoring engines (seen in the Harrier and Yak-38 Forger); phased array radar (seen in the MiG-31); infra-red search and track systems (seen in the MiG-29, MiG-31 and SU-27 fighters); and helmet-mounted sights (as in the MiG-29 and SU-27).
It therefore stands to reason that many of the features that will be standard on sixth-generation fighters will appear in other aircraft long before the first generation six jet goes on its first test flight, and this seems especially likely to be the case with the flight control systems for this next generation of aircraft. The fly-by-wire controls all but standard on today's fighters may be replaced by other systems, such as fly-by-optics, which substitutes optical fibers for wires, permitting faster data transmission and greater security against electromagnetic interference, such as will be seen on the Mitsubishi ATD-X fighter, Japan's fifth-generation fighter; or fly-by-wireless, dispensing with wiring of all kinds to relay information to the actuators controlling the flight surfaces, an approach seen in the experimental Portuguese UAV known as AIVA. The hydraulic actuators which actually control the flight surfaces might also be replaced by electric circuits ("power-by-wire"), an approach the designers of the F-35 are using in that aircraft. (Both fly-by-wireless, and power-by-wire, are expected to reduce aircraft weight and reduce the maintenance burden.)
Even more exotic are approaches which integrate flight control systems into an aircraft's wings to reduce mass and cost, as well as improve performance, and at least two are objects of interest at the moment, namely flexible wings, with which NASA has experimented using a modified F-18 (dubbed the X-53); and fluidics, which British researchers are experimenting with in the Demon drone that first flew last year.
We might also see the advent of intelligent flight control systems, which would enable onboard computers to automatically compensate for the failure of particular aircraft systems, or for damage incurred in flight. (This too is reportedly planned for the ATD-X.)
For the time being, though, it remains to be seen which, if any, of these approaches will set the next generation's standard.
A Sixth-Generation Fighter?