What will 6th Generation fighters look like?, page 1

BW23,

Mission:
Mission, Mission, Mission. A 'fighter' as defined by the USAF is an aircraft whose principle defined mission is that of shooting down other aircraft. Since we haven't seen a real air war since 1982 if not 1972, the question must be not /what/ but -why- a 'fighter' must exist.
Pull the hogs nose radar. Pull the wetted area of twin tails and huge stabs, pull the gaping maw of supersonic capable 'big gulp' inlets. Pull the 9-11G requirement. And what you have left is a platform that can do the basic mission of _surveillance_ and ground attack for hours longer at half the basic weight. Weight= cost @ 1million per 1,000lbs.

Fuel:
Carbon based fuels will become ever harder to pay for and indeed may become a 'restricted to X-class' energy nations in the first world. This means two things-
1. Reducing to an absolute minimum the number of training hours required. Every mission must be oriented towards active warfighter or peacetime 'monitoring' flight. Which means a robot is better for currency purposes.
2. Shifting to new, 'multifuel' capable, systems (such as already exist in ground turbines). Almost everyone can find or grow methane under their dirt. Almost everyone can make hydrogen if they have the electrical generation to zap their water with.
But to get there from here means changing the specs on how fuel is stored in what phase and with what kinds of intercooler/cryo/pressure ratings

Signature Control:
As others have suggested, the ability to COE _avoid_ combat is critical because current weapons system shifts towards distributed/netcentric means suggests that very low value assets (UAVs, LTAs, Missiles) may allow targets to be found simply by creating so many sentries that conventional LO will not sneak you past enough of them to matter. 'Active Optical Camouflage' may still be several years out but various electroluminescent screens/sheets/coatings have already been demonstrated and when combined with a _simple_ planform (no shadow zones) and _small_ airframe, they offer some amazing potential against human detection. Gated/Polarized filtering optics are another matter but will themselves be vulnerable to dazzle if not destructive attack. I also fully expect some truly exotic capabilities like hyperspectral tracking of wakes and cued seismo-acoustic systems, maybe even the first gravity well or EM disturbance systems (as a PCLS+).

Spectrum/Info Dominance:
Even with passive or optical based systems that have low or now side lobe and secondary radint detectable means, the ability to maintain control over own emissions while supplying useful battlespace awareness will be increasingly tough to do. Yet it wil remain essential for the same reason that RFLO only really works when you don't give the enemy a specific volume of airspace o concentrate their attention to: No see'em too good only works when they aren't putting up smoke signals.
Similarly, as open ended datalink architectures continue to expand and gain bandwidth, the option to both passively exploit and actively spoof message traffic becomes an ever greater threat.
Obviously you can do things like store and burst transmit (even use a jettisonable signal source) but there will be limits to what is achievable -at cost- without integrating an AESA equivalent comms array into your CNI package, just to keep datarates high enough for increasingly large IMINT and MASINT type transfers.
The directions this can go are immense but the basics will come down to creating a viable decoy/relay survivable network. Or making the platform itself sufficiently capable as to conduct it's own mission decisions, at least to the point of cueing a remote (ballistic submunition) fires system. Which brings us to-

Weapons System Interactions:
If diode systems don't reduce the powerloading:mass requirements of DEWS down to the level of say an ECM pod by 2015, they will not go into Gen-6. At least not as 100KW hard kill. Dazzlers are forbidden by treaty and pilotage bias but this may be less important so long as they are 'not deliberately intended' to burn out more the missile optics. The increasing use of BVR tactics may also be a factor but so long as RFLO remains dominant, you can expect an increasing shift to ever cheaper active/adaptive optics channels as first adjunct and then dominant spectrum modes.
Given the extreme threat posed to helos and transports in the <10,000ft trashfire envelope, I frankly don't believe we will be able to avoid active DIRCM systems for much longer anyway, MH-53 already mount AAQ-24 for instance.
Yet particularly if lasers go to weapons grade systems, we may need to look at the performance factors that design kinetic kill systems as a function of cost as much as capability. You will not want to linger in the 5-20nm zone as this will increase the likelihood of bus kills on the motor system. And you will not want to limit yourself to single-try 'hit or miss-ile' systems wherein, /in addition/ to hard and soft kills on the weapons, there is a limited energy reserve that drives the number of passes each weapon can make. Something like a cross between an ARRMD and FRSW may be necessary to put the missile well above the easy-to-point threshold of a nose-forward-and-down ATL aperture at Mach 6-10. Followed by a spread of Starstreak type miniwarheads which can both survive high-Mach bussing and perhaps make multiple and/or coordinated passes on a target to bleed it down for the 'perfect kill' while saturating any secondary TADIRCM type defense.
Of course, all this presupposes the notion that systems like ABL and/or relay mirror THEL do not redefine the limits of 'air superiority' altogether.
Which brings us to-

'Cost As An Independent _Tactical_ Variable':
If active optical threats, both for detection and weapons engagement become truly dominant without mediating counters from 'deflector shield' or active-optical observables reduction; the only way forward may be to go back /down/. Into the heart of the slingshot threat bubble. Down will get you a shorter horizon and compressed threat reactions. Down puts you nose-on to most threats against a haze riddled horizon filled with anaprop turbulent air. Air whose transmissivity properties can be further degraded by the likes of Chemring clouds and even conventional smoke. Down will get you a lot more drag but also a lot more (body vice wingborne) lift, rewarding the cruise-style or even scissor/oblique wing design with a big fat wedge of a body to stuff systems into. Down removes a lot of problems with targeting through weather yet adds just as many more with weapons delivery (ballistic solutions no long work and laydown is just as short-window crippled for accuracy as ever) and comms LOS.
Down with standoff means reducing the warhead to a bare minimum (10-25lbs) to keep the propulsion scaling acceptable AND adding either a popup (LAM) targeting drone and AMSTE type steering network receiver system. Or an independent seeker on every kill vehicle.