2023/02/11

A 6th generation combat aircraft for Europe

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The normal ideas for a 6th generation fighter / combat aircraft follow the established triad of air dominance fighter (F-22 continuation), strike fighter (F-35 continuation) and bomber (B-21?).

The usual expectation is that more gadgets will be added (including lasers powerful enough to at least damage optical and thermal sensors). It's also widely believed that a 6th generation combat aircraft will be optionally manned if not outright unmanned, and cooperate with drone 'wingmen'.

I have my own thoughts about what would be sensible instead, and I only really pay attention to defence of Europe. So the scenarios are either an air power-supported land war in Eastern Europe (worst case vs. Russia, PRC and Turkey at the same time) or an air/sea war with land-based air power and air defences facing seaborne aerial threats (including quasiballistic missiles). The latter scenario is of lesser importance, as it relies on the U.S. turning full-blown fascist and hostile and they could alternatively use SpaceX Spaceships to haul warheads into low orbit for bombarding Europe (by the 2030's). So the main scenario is a land/air war in Eastern Europe.

There are many land-based, non-manned aviation alternatives to manned air power and even many ground alternatives to most unmanned airpower, such as firing quite cost-efficient surface/surface missiles at targets within 120...500 km.

A 6th generation combat aircraft would thus have to be able to hide on airbases and airports 500+ km away from the ground combat and it could best justify its huge expenses by filling unoccupied tactical niches. I will probably later publish a draft text on what can substitute for manned air power in what roles. For this blog post I'll just state that I think about a survivable radar platform for about 60,000 ft altitude, using radars both to find air targets and ground targets, albeit this may be done by different aircraft versions with different radar bands.

unofficial X-44 Manta depiction, (c) Fox 52

The platform would be roughly similar to the X-44 concept, albeit with more spaced turbofan engines and consequently a single centreline underbelly air inlet (to still have S-duct).

I chose the X-44 concept as a starting point because the entirely tailless design helps much with radar stealth.

The spacing would be necessary to enable having the same radar in the tail as in the nose (thrust vectoring might be limited by the radome). The radar would use a rotating ~45° angled AESA antenna, enabling semispheric coverage for each nose and tail radars and thus full spherical overall radar coverage. The aircraft could freely manoeuvre at 60,000 ft with supercruise speed (afterburners not needed, actually).

All missiles would be kept in a central rotating magazine weapons bay (or two) between the turbofans, similar to what some bombers have. There would be at least six missiles and a few free-flying DRFM decoys in there.

https://www.thedrive.com/the-war-zone/31799/proposed-facility-would-drastically-cut-down-time-required-to-arm-bombers-on-guam

The missiles would mostly be dual purpose missiles, capable of hard-killing incoming rockets and killing pursuing aircraft at similar ranges as today's best infra-red guided missiles. This entire aircraft's purpose would be more similar to today's AWACS (AEW) and J-STARS aircraft than to a F-22. 

Munitions would primarily be fired from the surface, but the bird's view at 60,000 ft is an important niche capability to make full use of such surface-based munitions.

The idea is to feed radar data from bird's view perspective into a networked air and ground war effort. This includes air contact data (detection by L-band radar) and ground contact and ground mapping data (X-band). A detected hostile fighter would not be engaged by this aircraft, but by ground-based missile launchers at command of a ground-based air war command. This aircraft concept would not be meant to fly over hostile ground, but it would be able to venture out to sea (Baltic or Black Sea, for example) and its stealth, flying performance (altitude, speed) and missile countermeasures would enable it to fly close enough to the ground battle for a useful field of view into hostiles-controlled terrain.

The X-band radar version (not both radar versions on one plane) could use leads given by the longer avelength L-band version to determine the vectors of aerial contacts more accurately than even the combined contact info of multiple L-band version aircraft. The X-band radar would still mostly look at the ground (or surface at sea) and at what flies or floats below the surface radar line of sight, though.

The countermeasures would include at least one laser powerful enough to render infrared, UV and visible light seekers on missiles near-useless and possibly even to badly damage the seeker of active radar-guided missiles. The dual purpose missiles would try to trigger the fuse of hostile missiles, but also try to damage or destroy said missiles (maybe even with EMP warhead against radar-guided missiles?).

The aircraft would transit about 500 km per sortie, so a useful on-station duration of one hour would require about 3,000 km range in a high-supercruise-high flight profile with full missile load. This range, the survivability features, the munitions bay and the two big radars would lead to an aircraft rather a bit larger than the F-22. This causes huge challenges on the ground, as hiding would be difficult. Moreover, such a highly complex aircraft would rather not permit sustaining more than one such two-hour sortie per day, and midair refuelling wouldn't help much to extend flying hours per day, but require much extra effort and permit more distant basing.

So assuming we would need 10 on station, that would be a total requirement for 240 aircraft + reserve for not ready aircraft (another 100 maybe) + attrition reserve. The required total might be 500, difficult to afford for such a niche capability. 10 on station might not even suffice to satisfactorily cover the entire span from North Cape to Suez Canal or Caucasus region for NATO. Maybe the cost would be prohibitive, ensuring that an approach with only low altitude drones and ground-based equipment replaces the air war even if the opposing forces still insist on air power as we know it.


S O

defence_and_freedom@gmx.de

 

edit: You may have read that L band is no magic bullet against RF stealth and requires huge antennas to  create a narrow beam main lobe. Wavelengths longer than X-band are not much used in fighters because they are indeed not so good at accurate 3D measurements. Whatever band would be used (could be UHF for LO air threat detection, actually) doesn't matter so much. Longer wavelengths are worse for angular resolution, but fine for ranging. Two radars may detect and track a target over time getting just 10...20° angular resolution, but accurate distance readings. Their own position would be known accurately. Fusing thee two tracks allows for computing the position of the contact even if there are many contacts at the same time in the same beam. The algorithms for this are fairly straightforward; you just need to rule out implausible movements. Finally, you get a position accurate enough that a high-powered X-band radar can stare at it, switch off filters for a short range band in its narrow beam and even a tiny echo would suffice to detect a LO cruise missile at a useful distance. Moreover, LO aircraft contacts can be confirmed with zoomed IIR cameras.

Finally, long wavelength radars can move their main lobe to determine when the contact doesn't generate such a strong echo any more (because the main lobe ends), they do not just get the ibinary info whether contact is detected by main lobe or not. (See here for basic info on radar lobes: https://basicsaboutaerodynamicsandavionics.wordpress.com/2016/08/11/radar-fundamentals-part-ii/ )

The requirement for having two long wavelength radars 'seeing' the same contact does add to the quantity of radars that need to be in action (and thus radar airraft on station), of course.

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10 comments:

  1. Surveillance doesn't seem to need human input and rather looks like something that could be automated with a cheaper system. Part of the coverage might be done via balloons.

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    1. "balloons" as a word simply doesn't belong into a conversation that's about survivability in conventional warfare.

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    2. I beg to differ. Balloon based systems in the form of airships did play a role in the battle of the Atlantic in WWII and I think they can again in modern times provide surveillance to far greater areas than aircraft, everything but the frontlines. I think in a hypothetical war between Russia and NATO, most of the Atlantic and Europe would be observed by unmanned balloon systems, some of them solar powered airships.

      The balloons will have to be small and inexpensive to be used in frontline service. Miniaturization might provide some difficulties, but I don't consider it impossible. Take a transparent party balloon or a condom, inflate it with hydrogen, give it a sky hook, and you have a nice resting place for small drones to observe and where from to detach in case of danger or on a mission to drop ordnance.

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    3. If you're just using them over your own territory it makes it easier to use decoys Most of them should be just ballons toting mock up equipment. Other balloon decoys to tote threat emitters. The emitters may be expensive but they'll still be cheaper than an actual sensor setup. Extensive use of decoys uses up enemy missile stocks and over time forces them to accept a certain amount of survellience (due to missile depletion).

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    4. Blimbs were used in WW2 in the Caribbean (NOT in the Atlantic), but they were rather inconsequential, as they only mattered in daylight and German submarines did not attack convoys in daylight anyway.
      Balloons, blimps and Zeppelins were little more than targets by WW1 already. The only balloons in widespread WW2 service were tethered barrage ballons, which were rather ineffective.

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    5. A high performance aircraft may survive within 100 km of hostile area air defences, and in absence of powerful jamming it would be able to see up to 250 km behind those powerful air defences.
      A flimsy low cost balloon would struggle to make use of a 20 km radar. And cheap decoys don't emit like a high quality radar, so they wouldn't be convincing.

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    6. I was wrong about the use of airships in the Atlantic, but I like where the discussion goes, unmanned miniature balloon/airship systems for surveillance and as decoys. They won't look far, but can be a persistent presence of surveillance combined with loitering munitions. The problem is about making this solution cheap and tiny.

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    7. Balloons are nonsense. The cheap ones can be killed with a single howitzer shot. The ultra high-flying ones need sensors of more than 30 km range against car-sized land targets, and that means the payload costs millions - they're worth a missile that goes that high. And that's before taking into account that even a moderately powerful laser can easily pierce a balloon.

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    8. The main advantage of airships is their endurance (they don't need power to keep their altitude), putting a long-range radar with high power consumption on an airship doesn't make any sense, it will quickly run out of fuel for the electrical generator for the radar, and then it will take forever to get back to base to refuel (airships are very slow, in a headwind they may not be able to move at all).

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    9. Aerostats were used by the US in Afghanistan and Iraq. Maybe not in the frontline, but further back there might be a space for such systems.

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