H-20 bomber (with H-X, JH-XX)

ougoah said:

Because variable geometry is awesome and is actually a step further. Future generation fighters and UCAVs are almost definitely going to incorporate variable geo as part of distinguishing major features. I'd say variable geometry (not just swing wing) is going to be the core of next gen kinematic performance side tech including range improvements which this is really going to be a great part of anyway.

I really don't understand why some members are refusing the believe that H-20 might actually be variable geometry. Some are refusing to believe Chinese military aviation is incapable of building a flying wing design because it's presumably hard. Wrong. It's not hard and China's done several known flying wing prototypes and flying, operational flying wing aircraft. None of them are piloted though. It's a mistake to assume H-20 not being only flying wing means it's somehow "worse".

If we assume the hints that there are variable geometry wings/stabilisers, I would consider that quite a step beyond just doing a B-2 design copy. The variable geometry has been hinted at making the aircraft much more controllable for take offs and landings. It becomes a plane flying wing when cruising. It's possibly even more flexible with variable geometry. This aspect only improves the design over one that doesn't have a variable geometry design but with weight and complexity penalties of course. Maybe it becomes much better for slow speed, low altitude flight and makes landing safer and easier? While still retaining all the benefits of flying wing ... since you know... it is a flying wing when those control surfaces move to align. It's basically having the best of both worlds. Flying wings should be easy for China since they've been publicly flying at least one (GJ-11 prototype) since 2013 and probably have been flying them not so publicly well before that.

Click to expand...

ougoah said:

I'm not equating hypothetical folding tails on H-20 with any potential to exploit that particular piece of technology on future UAVs. Variable geometry usually enhances an airframe. I mean that's the whole point. I'm just saying that you don't need a "traditional", non-variable flying wing design. Folding tails isn't a big deal. If anything it could only be better than applying non-variable design on H-20. Anyway I already said all of that was hypothetical because this little detail seems to have worried some people for mysterious reasons.

Again the point is that folding tail doesn't mean the aircraft is less advanced and less capable. It is more advanced and can only be a net positive effect because it ought to be simple enough not to apply it. One reason offered in the past was due to low speed and low altitude control. During typical flights between landing and take off, they can simply make any moving section align and hence it preserves all those LO characteristics but with the added benefit of being able to handle low speed, low altitude controls even better than without a variable section. What I don't get is why such a hinted feature is considered a departure from what fanboys consider the best outcome for this project.

Click to expand...

latenlazy said:

Variable geometry in general means that your aerodynamic design and control laws aren’t sophisticated enough to do away with the need for draggier and more mechanically complex structures. This may not reflect deficiency, as sometimes you just want higher performance parameters than what is doable with a fixed geometry design. Nonetheless, if you can do something through a fixed design that is normally easier to achieve with a variable design that’s a mark of more advanced capabilities, not vice versa.

Click to expand...

ougoah said:

That's quite wrong because the details of what you want to achieve really matter quite a bit.

You simply can't make a school bus fly like an F-16 with current engine technologies no matter how good your aerodynamic design and control laws are. You are just making a totally empty meaningless statement without even acknowledging how important and complex the details are.

The choice for variable geometry may be because of design issues or it may be because certain aspects of the design simply cannot be changed due to many reasons. You can't make a low altitude bomber also a great interceptor and also a great dogfighter unless you have the means to change critical aspects of the design like sweep angle or centre of gravity. Variable geometry is the most realistic solution to problems where the customer really will not compromise on very difficult to fuse characteristics. It's not a perfect solution but no one is even capable of doing this yet. It will definitely be a part of future generation aircraft from the US to China.

Aerodynamics is not a problem any more. Certainly not for China. Flight control maybe that's where the engineering really steps in. Variable geometry makes flight control more complex is some ways. FC comes after aerodynamics not before and deals with the problems given by its aerodynamics. So if aerodynamics is more or less set due to purpose - stealth and bombing, then there are only so many ways this can technically be achieved realistically in this day and age with finite budget.

Click to expand...

Bltizo said:

Nowhere in my post did I write anything about folding tails on the aircraft being less advanced or less capable.


What I am saying however, everything has a tradeoff.
Adding in folding tails in a wise manner may have a minimal effect on stealth, however adds weight and complexity to the aircraft, and is fair grounds for the basis of skepticism that others like flateric have expressed given the context of the PRC aerospace industry demonstrating multiple successful flying wing UAVs.
Whether the PLAAF deems it worthwhile to achieve benefits in flight control it offers is up to them.


I wrote that ultimately the idea of H-20 not having folding tails and the idea of H-20 having folding tails are both plausible.

Click to expand...

latenlazy said:

Variable geometry in general means that your aerodynamic design and control laws aren’t sophisticated enough to do away with the need for draggier and more mechanically complex structures. This may not reflect deficiency, as sometimes you just want higher performance parameters than what is doable with a fixed geometry design. Nonetheless, if you can do something through a fixed design that is normally easier to achieve with a variable design that’s a mark of more advanced capabilities, not vice versa.

Click to expand...

latenlazy said:

Let me put it this way. Swing wings went out of fashion for a reason.

Click to expand...

ougoah said:

And I'm in agreement with this.

Both speculations are indeed plausible and it's simply wrong to have a basis of skepticism over moving tails due to poorly conceived suspicions of "capability" in whichever engineering compromise and design choices were made.

Click to expand...