J-20... The New Generation Fighter III
- Thread starter siegecrossbow
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Go to hell, really.
SAC is still an AVIC company and it doesn't stand to reason that SAC would depart from standard operating practice. A J-31B might have EODAS stapled on, but there's no indication of it. For all we know, the J-31B can predict the future and win you the lottery, but there's no evidence that such a capability exists.
LERXes / Lifting bodies; show me where the LERXes are on the J-31. The F-35 which influenced the J-31 is not believed to utilize LERXes. Show me indications that the J-31 is a body lift design; compared to the F-35 it is relatively squat.
In any case, the J-31, from my measurements, will have between 50 and 54 m^2 of wing area, if we assume body lift is included. If you go by a weight of 25 tons, which is less than the PLA commentators are claiming, that's a F-35-like wing loading of 462-500kg/m^2. It's very high wing-loading, and if we assume they run RD-33MK engines, that's 17.95 tons of thrust. .718 T/W ratio here. Looking very good, aren't we?
SAC is still an AVIC company and it doesn't stand to reason that SAC would depart from standard operating practice. A J-31B might have EODAS stapled on, but there's no indication of it. For all we know, the J-31B can predict the future and win you the lottery, but there's no evidence that such a capability exists.
LERXes / Lifting bodies; show me where the LERXes are on the J-31. The F-35 which influenced the J-31 is not believed to utilize LERXes. Show me indications that the J-31 is a body lift design; compared to the F-35 it is relatively squat.
In any case, the J-31, from my measurements, will have between 50 and 54 m^2 of wing area, if we assume body lift is included. If you go by a weight of 25 tons, which is less than the PLA commentators are claiming, that's a F-35-like wing loading of 462-500kg/m^2. It's very high wing-loading, and if we assume they run RD-33MK engines, that's 17.95 tons of thrust. .718 T/W ratio here. Looking very good, aren't we?
Oh snap
I'm sorry but this entire line of argument is invalid if you consider the idea that "J-31" is a private venture project/demonstrator... There is no indication that EODAS exists yes. But you'd be stupid to use what we can see on the current plane as what the in service plane will look like.
And what AVIC operating procedure is stopping SAC to make changes to further prototype aircraft down the road? This is a plane they're trying to entice PLA with, it isn't something the PLA have a requirement for as of yet. In that way it is a demonstrator aircraft, different to J-20 which is a prototype meant to go into serial production.
Besides, this plane's paint scheme is so dark there could very well being EODAS windows like there are on J-20 but we haven't gotten clear enough pictures to see them.
what makes you assume F-35 influenced the J-31? And if F-35 did influence J-31 what's to stop it being equipped with LERX? And I think we need to clarify just what an LERX is. For instance, what we see on J-20 behind the canards are LERX. But F-22 also has "LERX" combined with the air intakes.
As for lifting body... I think it's meant to be relative? There is no particular parameters you have to abide to for the body to provide lift.
I thought the one thing we had all learnt from arguing over J-20s manouverbility all those months ago was that we shouldn't eyeball aerodynamics.
And no one is denying RD-33s are currently underpowered for this aircraft. It is meant to be powered by two 9.5 ton engines so your entire argument wrt TW ratio is moot.
And at the end of this entire post you still hadn't provided any good argument for how F-35 will have much improved performance compared to this plane. In terms of avionics we can't compare them because we don't know what J-31 will be equipped with. Aerodynamically, we can only rely on mundane facts like TW ratios and eyeballing wing loading without taking into account any body lift to make decisions of its kinematic performance which is only slightly less than completely useless.
If you consider my line of argument you have to remember that the existence of things is based on principles of parsimony. If you go by "it's possible" as opposed to likely, we can say that the J-31 has a new weapon that, when activated, can cause Obama's head to explode. Theoretically possible, but not particularly likely. As far as the aircraft being too dark; consider the F-60 model currently on display in Zhuhai. There's not even an indication for Irst. There is basically no reason to consider the J-31 will receive EODAS at this point other than the fact that the F-35 has it.
With regards to making changes to prototypes, I did have a link for a comparison between J-10 and J-10A aircraft, and the changes were not significant and did not involve adding significant features. Some parts were moved around to adjust the aerodynamic formula, but why, at this iteration, add EODAS?
Let's agree here that leading edge root extensions (LERX) refer to protrusions in front of the wing which energizes incoming air to create vortices, increasing lift at high AOA. In this case, the F-35 does not have LERX; the F-22 has subtle, almost undetectable lerxes on the edge of the engine intakes.
In this picture, we may see LERXes, but the picture is very blurry and hard to tell.
In the following fan diagram, there's no LERX.
As far as the F-35 being a large influence on the J-31, look at the intakes, the general planform, the hacking on LM and LM's contractors, and the size of the J-31.
Look, let me redo the weight estimates. If you accept the general F-35 planform as a basis for the aircraft weight, then scale it up for the J-31 wing area, you get something around 23 tons fully loaded. However, you've got to consider that the F-35 uses carbon nanotubes to reduce weight, and if you consider that, 24 tons or 25 tons becomes reasonable as an estimate for the J-31. In either case, 19 tons from two engines still gives you a .76-.8 T/W ratio loaded; and you do have to remember that the 9.5 ton engines are currently vaporware projects that only exist via a report on Jane's. There are no working models of the 9.5 ton engines in operation.
T/W-wise, the F-35 is likely going to be better simply because of the dramatic lead by the United States in terms of engine technology. Remember, the F-135 is now expected to be a 190KN class engine, up from 180KN a while ago, and reports indicated it managed to breach 200KN in testing. The F-35's thrust to weight issues will likely be well-controlled by simply having an incredibly powerful engine. It's the, *chuckles*, American way.
Let me define my positions clearly so we know what we're arguing about.
-J-31 is a low-end aircraft with less ambitious goals than the F-35, aiming to produce a reliable stealth aircraft for low-cost.
-J-31 is a strike aircraft, not an air superiority aircraft.
The first position is that I think the J-31 will likely be inferior to the F-35 in the near-term. It's simply less ambitious as a project, the Chinese have engine problems, and the Chinese don't have the vast experience the Americans have in aerodynamic shaping; compare the J-10 to the F-16 or the Rafale for that matter.
As I've said before, the wing loading on the J-31 is better, but the T/W is likely going to be worse. These two factors may offset each other, or they may not. The J-31 also lacks the EODAS you see on the F-35; it is, as I've said before, a less ambitious project.
The second position is that the J-31 is a strike aircraft. Let's first mention a few things: The J-31 has a small radome. Its radar will probably be in the F-35-class, and the F-35 is also a strike aircraft. The J-31 also has wing loadings comparable to that of other strike aircraft; if you're optimistic, it's somewhat worse than a Su-30MKI or Su-30MKK when it comes to wing-loading. We also generally don't see LERXes or other structures designed to increase max AOA and consequently instantaneous turn rates.
MiG-29
Banned Idiot
J-31 does have LERXes, small but it does, F-35 and F-22 also have small LERXes.
its lerxes are not like those on F-18 or MiG-29 but are LERXes.
LERXes are also called strakes
Its chines also generate some vortices that create some lift.
That lift is most of the fuselage lift it generates.
J-31 is more or less a F-22 type airframe with tiny wings like F-35.
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MiG-29
Banned Idiot
it is possible
[video=youtube;ntZDAS4fCPA]https://www.youtube.com/watch?v=ntZDAS4fCPA[/video]
[video=youtube;F5yzzS0PnG8]https://www.youtube.com/watch?v=F5yzzS0PnG8[/video]
but is not easy to make it specially like J-31. for a reason the americans made F-35 single engine
Fellas, this is the J-20 thread, we have a dedicated thread to the J-31, ya might want to move your posts over there?
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