Shenyang / Chengdu "6th Gen" Aircraft - News and Analysis

[JetBrain]

vertical fins do not need the rudder to stabilize all the time, the vertical fins straight up the flow by becoming walls that are most of the time in the symmetric line that cuts the fuselage in two sides longitudinally or what we call fuselage longitudinal axis . for a reason they are called vertical stabilizers and most of the time the rudder is a small part of them.
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Mirage III for that reason used a fin, not an all moving vertical fin like SR-71 or Su-57 or split rudders like B-2.

J-36 or any flying wing needs to create drag reducing lift to apply a differential force.

We have to face the reality, these tailless aircraft prioritize stealth and are better than 5th generation in stealth terms but in controlability, no they are not as good, most aircraft for a reason have ventral or dorsal fins with rudders, which is only a small part of the vertical fin.

According to the observables-agility matrix in "Impact of Agility Requirements on Configuration Synthesis" of NASA, the agility of tailless configuration 2408 is in the same class as that of the conventional configuration 2402.

 

[Avimimus]

Watch videos of birds in flight, their tails often get twisted to near-vertical or turned into an /\ shape as they maneuver

A lot of manoeuvring in birds and bats is done through wing tip deflection, with the tail being used more often in a role similar to that of flaps (trim and lift control). There are exceptions of course, here you can see the tail being used sometimes to deal with a cross-wind:

View: https://www.youtube.com/watch?v=iJff3J_9jVs


Overall though tails are flat (i.e. oriented like a horizontal stabiliser) and integrated into the trailing edge of the wing. So, they'd be classified as tailless design with some polymorphic abilities.

It is worth noting that long tailed versions of birds, bats, and pterosaurs are all well documented, but they were eventually replaced by tailless lineages.

Not directly comparable to aircraft, but I wouldn't be surprised if there isn't a reason for this that also applies to some types of aircraft in the future. Look at the amount of weight the active controls the Boeing Spanloaders would have required in the 1970s, now look at the weight of modern computers and the ability to do things like have distributed airflow sensors... there are a lot of technological limitations against distributed lift designs which are increasingly being overcome.

 

[Avimimus]

According to the observables-agility matrix in "Impact of Agility Requirements on Configuration Synthesis", the agility of tailess configuration 2408 is in the same class as that of the conventional configuration 2402.

Admittedly though, that also makes it the same class as 2401 and 2403 (if the illustrations are to be believed)!

 

[lancer21]

Just as a general reflection on the emergence of the CHADs.

Backs in the day, the 4th generation US F-14, F-15, F-16 (and later F-18) were the first of their kind, the standard setters against which every other 4th gen was measured against (MiG-29, Su-27, Eurocanards, J-10 etc). Then the US F-22 was the first heavy 5th gen against which every other heavy 5th gen is measured against (J-20, Su-57). And the US F-35 was the first medium 5th gen against which J-35, KF-21, KAAN etc. measure against.

But now, with China's unveiling of the 6th generation J-36 and J-50, it is THEM who are benchmarks, the standard setters against which every other emerging 6th gens will measure against. How times have changed.

 

[red admiral]

OTOH controls on the wings also have a longer lever, so a drag-rudder near the tip has a considerable multiplier to its effectiveness that a conventional rudder doesn't.

That's quite configuration dependent. You're also having to deploy those tip drag rudders a lot to counter higher yaw instability than with a "fin" which eats into drag. It very much depends.

According to the observables-agility matrix in "Impact of Agility Requirements on Configuration Synthesis" of NASA, the agility of tailless configuration 2408 is in the same class as that of the conventional configuration 2402.

It's also important to note that this is with yaw thrust vectoring and additional aerodynamic yaw manoeuvre devices. It also shows just how sensitive the configurations are to some parameters e.g. Thrust/Weight in order to provide both thrust and control power

 

[DWG]

That's quite configuration dependent. You're also having to deploy those tip drag rudders a lot to counter higher yaw instability than with a "fin" which eats into drag.

Whereas the vertical fin and rudder (and potentially significant fuselage side area*) are contributing significant parasitic drag at all times.

There's no single perfect solution. There are multiple ways to control pitch, roll and yaw, and which works best for your particular problem may be radically different from someone else's. Look at all the different ways we have of controlling pitch - conventional tail, canards, inline triplane, levcons, etc. No one finds it extraordinary that different designers choose different solutions. Different solutions for yaw control are no different.

* Think of all those WWII era rudder fillets that had to be added when lateral stability proved insufficient, or tails enlarged, entire extra tails added and so on.

 

[paralay]

The aircraft must have a wing and an engine, the rest only hinders flight. In the future, it should be a single whole, a wing that creates not only lift, but also thrust.
At the same time, the planes will be built on the basis of a completely different principle of flight, you know, on which...