J-20 5th Generation Fighter VII

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Temstar

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might as well just design a new jet with all those changes

Well they did say J-20 airframe was going to be a common platform for lots of things. I imagine this would be similar to a F/A-18C/D to F/A-18E/F type thing where it's indeed very nearly a new plane. If this thing does fly perhaps it would lead to a 5.5 gen fighter standard?
 

Blitzo

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Well they did say J-20 airframe was going to be a common platform for lots of things. I imagine this would be similar to a F/A-18C/D to F/A-18E/F type thing where it's indeed very nearly a new plane. If this thing does fly perhaps it would lead to a 5.5 gen fighter standard?

It makes sense to do studies and patents for lots of weird and wacky configurations.

Whether any are pursued or not, is only something we can speculate on.


But the only variants we take seriously are the ones that are rumoured in the grapevine as being pursued, so far the only variants being a J-20 variant powered by WS-15, and another one possibly being a tandem twin seater variant.

Everything else depicted in various patents and studies is not worth putting too much thought into unless the grapevine or the insiders give indications that they're being actively developed, IMO.
 

plawolf

Lieutenant General
I am not sure about the retractable canard, but I think the folding tails are a stroke of genius that is easily attainable with existing tech levels, as they could pretty much go off-the-shelf with carrier fighter folding wings designs as a pretty good starting point.

Obviously they will need to put in place additional actuators and what not for the shape change, but the J20’s design already have plenty of room in the tail stings for those.

I think this is a pretty viable design that could potentially be incorporated into a future J20 version as almost a bridge between 5th gen and true 6th gens.

Mate the foldable tails with TVC WS15s and you could have one hell of a performer.

It is also worth noting that in the design, the tails appear to be able to fold both upwards and downwards.

Maybe they were just playing with various configurations, but it also opens up the possibility of dynamic positional changes during flight to further boost agility.

Aside from the obvious roll and pitch applications from asymmetrical canting of the tails, one particularly interesting potential application would be to maintain full yaw control authority during extreme high alpha manoeuvres.

One of the main issues with extreme high alpha manoeuvres is that the body of the plane start to block airflow to the tail, thereby causing you to loose yaw control authority, and in effect place a hard cap on how much AoA you can safely pull.

There are ways around that like sweeping the tail back and extending it past the wings, like on the J20, such that the tips are still exposed to incoming airflow to give you some yaw control. But that only gives you partial control as only a small part of your tails are getting any airflow.

With the tails canted downwards under the body of the plane, you can have full paw control authority irrespective of AoA. Not only would this allow you to pull higher AoA, but you will have much more responsive controls at those extreme AoAs.

I would not be surprised if we seen this being flight tested within the next 5-10 years.
 

latenlazy

Brigadier
I am not sure about the retractable canard, but I think the folding tails are a stroke of genius that is easily attainable with existing tech levels, as they could pretty much go off-the-shelf with carrier fighter folding wings designs as a pretty good starting point.

Obviously they will need to put in place additional actuators and what not for the shape change, but the J20’s design already have plenty of room in the tail stings for those.

I think this is a pretty viable design that could potentially be incorporated into a future J20 version as almost a bridge between 5th gen and true 6th gens.

Mate the foldable tails with TVC WS15s and you could have one hell of a performer.

It is also worth noting that in the design, the tails appear to be able to fold both upwards and downwards.

Maybe they were just playing with various configurations, but it also opens up the possibility of dynamic positional changes during flight to further boost agility.

Aside from the obvious roll and pitch applications from asymmetrical canting of the tails, one particularly interesting potential application would be to maintain full yaw control authority during extreme high alpha manoeuvres.

One of the main issues with extreme high alpha manoeuvres is that the body of the plane start to block airflow to the tail, thereby causing you to loose yaw control authority, and in effect place a hard cap on how much AoA you can safely pull.

There are ways around that like sweeping the tail back and extending it past the wings, like on the J20, such that the tips are still exposed to incoming airflow to give you some yaw control. But that only gives you partial control as only a small part of your tails are getting any airflow.

With the tails canted downwards under the body of the plane, you can have full paw control authority irrespective of AoA. Not only would this allow you to pull higher AoA, but you will have much more responsive controls at those extreme AoAs.

I would not be surprised if we seen this being flight tested within the next 5-10 years.
That tail design was an idea I’ve had a for a few years now, and I’m more than certain I’m not the first person to think of it. I’m skeptical of its efficacy in practice. The aerodynamic control laws for this sort of design looks to be pretty complicated, you’re going to lose the ability to change the wing camber in the area that the tail occupies, and I’m willing to bet that when you’re using the tail as a pitch device it will introduce a lot of drag and even turbulence from the gap formed during deflection.
 

siegecrossbow

General
Staff member
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Latest screen shots of J-20 from a CCTV documentary about Dingxin Airbase!.

@沉默的山羊 from weibo.

43LJScu.jpg


429ctki.jpg


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YwaHCZy.jpg


Check out this image of the (blurred) cockpit.

Lp4kQ9N.jpg
 
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plawolf

Lieutenant General
That tail design was an idea I’ve had a for a few years now, and I’m more than certain I’m not the first person to think of it. I’m skeptical of its efficacy in practice. The aerodynamic control laws for this sort of design looks to be pretty complicated, you’re going to lose the ability to change the wing camber in the area that the tail occupies, and I’m willing to bet that when you’re using the tail as a pitch device it will introduce a lot of drag and even turbulence from the gap formed during deflection.

Chinese designers have never been scared of complex, although they obviously have a preference for simpler elegant solutions over complexity for complexity sake, with the J20 side bay rail design a classic case in point.

In terms of aerodynamic costs, well indeed there will be some penalties when you deploy the tails, but you also have massive savings when the tails are retracted compared to the current configuration, so it’s a balance, like all design choices.

However, we need to remember that control surfaces rarely if ever fully deflect to their maximum theoretical limits. Just look at how little the J10 and J20 canards deflect in airshow even during high AoA turns. I think it’s a safe bet to say the same would apply to the tails if this concept was fielded.

Most of the time probably only tiny deflections would be needed, which will minimise the aerodynamic costs.

That conceptual drawing was just a very basic preliminary one, which I would expect to be refined through computer and wind tunnel modelling and testing as they take the design forward.

They may be able to finalise the design more or less as depicted, or they might incorporate the tail design with a whole new wing design, maybe along the lines of the Boeing Bird of Prey design. Although obviously such a radical design departure from the baseline J20 would likely make that a one-off Chinese X-plane rather than an operationally fieldable J20 follow-up variant.

I fully expect them to extensively test this concept, and am optimistic that they can make it workable as a J20 variant.

Whether the trade-offs are worthwhile would probably only be determined through testing.

But considering that 5th gens would expect to spend the lion share of their lives well outside of WVR, I think the RCS and supercruise benefits from this design would be worthwhile even if they do take a performance penalty in WVR. Which incidentally is by no means assured. Indeed they may well find that the design yields gains in BVR as well as WVR, especially if they can make the tail position changes dynamic rather than having a set number of limited fixed configurations.
 
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