J-20 5th Gen Fighter Thread VI

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Hyperwarp

Captain
That'll result in a complete revamp of the aerodynamics so it won't happen.

That said, I don't think that the USMC would've considered canards on the JAST concept if it is that bad for stealth.

[*IMG]
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We can add Northrop-Grumman to that list as well. The same people who built the YF-23 proposed a delta canard variant for the Naval-ATF competition.

natf-23.jpg
 

Inst

Captain
Canards promise trade-offs in RCS vs tailplanes, because the latter can be better merged with the main wing to reduce RCS scatter. The difference between a canard delta aircraft and conventional aircraft is that the canards are just tailplanes moved forward.

That said, if the J-20 has both stealth and maneuverability targets, it makes more sense to ditch the all-moving tailfins once TVC comes online than it does to ditch the canards, since the tailfins (which exist on the F-22, J-20, F-35, Su-57) add more drag than the canards do, and impose a comparable stealth penalty.
 

Air Force Brat

Brigadier
Super Moderator
Canards promise trade-offs in RCS vs tailplanes, because the latter can be better merged with the main wing to reduce RCS scatter. The difference between a canard delta aircraft and conventional aircraft is that the canards are just tailplanes moved forward.

That said, if the J-20 has both stealth and maneuverability targets, it makes more sense to ditch the all-moving tailfins once TVC comes online than it does to ditch the canards, since the tailfins (which exist on the F-22, J-20, F-35, Su-57) add more drag than the canards do, and impose a comparable stealth penalty.

and here you are 180 degrees out of phase with the real world of aerodynamics, canards are always making positive lift, (a good thing), and in the process making drag! (a bad thing), so the canards are inherently more "draggy" than the tail feathers. Now while the canards are making more lift, they are in "clean air" and are likely more effective per size and moment arm than tail feathers which reside in "dirty air"?

you correctly assert that the main wing is able to "mask" the tailplanes, while the canards are standing out front.... (they may "mask" a portion of the main wing head on, but at more oblique angles, not so much), they will likely raise RCS from the frontal and possibly side angle.

the J-20 does not have "all moving" tailfins, the F-22 does have all flying stabilators, which are also used to roll the aircraft

in the end, its six of one, half a dozen of the other, both arrangements have strengths and weaknesses.
 
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Air Force Brat

Brigadier
Super Moderator
AFB is right, videos of the on last day, does show intermittent use of the after burner on some manoeuvres albeit very briefly and when full after burner as it goes vertical.

Thanks for being a good wingman! you're spot on, all you have to do is listen to the audio, and I would remind my Buddy Blitzo, the J-20's AB flame is bluish in cast, (indicating more efficient combustion)?

In any regard, the J-20 is not "underpowered", it climbs away very well as he pitches to the vertical and engages full AB! oh gosh, I just love this whole show, it is a reward for being a faithful believer in the J-20, and I would remind all that I have always judged this airplane to "fly very nicely", Zhuhai is vindication of Dr. Song and Yang Wei's beautiful bird! Congratulation's Chengdu, and Congratulations Gentlemen, your Chinese Baby is a beauty, well done!

now having said all that, maybe the PLAAF will fly this whole display after dark so my Brother will have a visual! (Guys are more visual Blitzo!) I'm more visual, this whole six minute or so flying display is amazing, as notable as the F-35A display this summer at RIAT, maybe more so!
 

Hendrik_2000

Lieutenant General
Henri K take on the J20 demonstration in Zhuhai airshow Interesting interview with Li Gang the test pilot for J 20. When ask to the performance of J20 the pilot said that J20 is as agile as J10. That should put and end to the myth that J 20 is underpower
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Airshow China 2018: Cockpit, Weapon bay, demonstration ... the J-20 is unveiled more
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2e8d649e1b274ce816887d2ce17d9964

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As in 2016, the J-20 fighter of the Chinese Air Force is present again this year in Zhuhai-Jinwan for the 12th edition of Airshow China 2018. But compared to two years ago , the aircraft dubbed Wei Long (威龙) by its designer the 611 Chengdu Institute of AVIC has unveiled more, whether in number of public presentation or demonstration content.

Starting with the number of aircraft - At the 2016 Zhuhai Air Show, while the aircraft's entry into service with the People's Liberation Army Air Force was not yet announced, two J-20 made a brief appearance of one minute during the inauguration of the event by flying over the runways of Zhuhai-Jinwan Airport. This year, the J-20 has more than doubled its presence at the same show and a total of four aircraft has come to deliver flying demonstrations for four days on the 6th, 9th, 10th and 11th of November.

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If the J-20 is still not exposed to the ground so that visitors can watch it closely, as the F-22 and F-35 have done at some air meetings, it remains that PLAAF has been much more open, and also more confident, to reveal and talk about its new spearhead dedicated aerial domination.

For example, interviews and press conferences were held last week in Zhuhai for the media to have the opportunity to speak live with the J-10B, J-20 and Y-20 pilots. LI Gang, who took charge of the first inaugural flight of J-20, has
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.

"It's transcendent (梦幻) ...", LI used this one word to summarize and answer the journalists' question about his J-20 flying experiences, a word that leaves room for imagination.


As for the cockpit of the aircraft that has never been shown to the public, the Chinese test pilot indicates that the cockpit of the J-20 is not only large and simple but especially very user-friendly.

"Everyone who has seen the J-20 cockpit is amazed by its simplicity and user-friendliness. Any switch or button, at a glance or touch we understand its function, day and night. LI said, "Chief Engineer YANG Wei gave us empty cockpit plans and stickers representing switches and buttons. And he asked us to stick them to the place that we think is the most reasonable on the plans. "

The shots from each elite pilot are then compared and compared to the others, and at least five rounds of review and selection took place during the development of the aircraft. From the plan on paper to the wooden model, then to the metal model, the engineers and pilots participating in the program worked on the smallest detail to arrive on an integrated mono-screen cockpit that they describe as a "science fiction" ".

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Hendrik_2000

Lieutenant General
(cont)

Apart from the cockpit of the J-20, the maneuverability of the plane also remains a question that regularly returns to the reflections. If some analysts say that the plane plays a role of hunter-bomber because of its imposing size, or a long-range interceptor like the MiG-31 at the time, what the Chinese designers and pilots say thinking J-20 would never put his "agility" in the background.

"The agility of the J-20 is at least equal to that of the J-10," says the test pilot LI Gang, "The engineers chose for a complex aerodynamic configuration to reconcile the low observability, agility and controllability of the aircraft ".


Other pilots, interviewed on television, also indicate that the aircraft is able to easily point the nose to the desired direction and accelerates easily. Inherited from this maneuverability of the previous generation fighter aircraft while enjoying an increased data integration capability and a much smaller radar cross section, the J-20 procured, again according to the pilots of the Chinese air force, with an "overwhelming advantage" over old-generation planes in both long-range combat and close combat.

Although the J-20 is not the first aircraft to adopt the concept of hands on handle and controller, or HOTAS in English, we note that the aircraft is the first Chinese fighter to have a righthand sleeve.




As an integral element of the low observability of the aircraft, the internal bunkers of the J-20 have yet no secret for the observers who followed this program since 2011. Indeed, many photos are circulating today on the aircraft, including demonstrators and prototypes, having opened their belly or side bunkers in flight and in flight.

But apart from the "stolen" photos, taken by passionate spotters in Chengdu for the most part, never until yesterday were the J-20s seen in a public event with open bunkers. And it's done now.

For the last day of the Zhuhai Air Show 2018, not only did the four specially-arrived J-20s all show up by flying, but two of them even opened all their bunkers in the air in front of dozens of thousand visitors.

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And the bunkers are not empty - Each J-20 is equipped with four long-range Air-Air missiles PL-15 in the two belly bunkers, and two short-range PL-10 missiles in the side bunkers.

We then had the opportunity to see the unique mechanism designed by the engineers of the 611 Institute to hold the PL-10 missiles out of the bunkers, without the door of these being forced to remain open, which is more appropriate in the case of close air combat.

The layout of the J-20 bellybars suggests that they would be able to house up to six missiles, if they have folding wings. Since the PL-15 is a long-range BVRAAM missile, according to Herbert J. "Hawk" Carlisle, a retired four-star general of the United States Air Force, he is a priori more long and bigger than the PL-12 and variants that have a smaller reach.

Unofficial sources speak of the development of a miniaturized version of PL-15 so that the J-20 can carry more than four in its bunkers, but this remains to be confirmed
 

Gloire_bb

Captain
Registered Member
I don't believe F-35's generation of stealth technology is as demanding of shaping as F-22's was and maybe J-20 has some of those ingredients too.
But shaping became important again on b-21, so apparently technology degraded from f-35 heights. More than that, it never even reached this level on various american stealth drones, they were as serious as possible with their shaping, at the same time.
Seriously, it is known what stealth requirements from JSF weren't especially strict: f/a-32 met them, too, after all. Thus it is a bad benchmark.
I won't be personally suprised if frontal RCS of J-20 will end up comparable(but with so much larger radar dish). With canards or without.
We will know for sure. Several decades later.
 

latenlazy

Brigadier
and here you are 180 degrees out of phase with the real world of aerodynamics, canards are always making positive lift, (a good thing), and in the process making drag! (a bad thing), so the canards are inherently more "draggy" than the tail feathers. Now while the canards are making more lift, they are in "clean air" and are likely more effective per size and moment arm than tail feathers which reside in "dirty air"?

you correctly assert that the main wing is able to "mask" the tailplanes, while the canards are standing out front.... (they may "mask" a portion of the main wing head on, but at more oblique angles, not so much), they will likely raise RCS from the frontal and possibly side angle.

the J-20 does not have "all moving" tailfins, the F-22 does have all flying stabilators, which are also used to roll the aircraft

in the end, its six of one, half a dozen of the other, both arrangements have strengths and weaknesses.
Tails generate positive lift and drag too. You don’t really think air decides to skip flowing over the tails because they’re tails do you? Yes, that positive lift might be smaller per area because of downwash from the wings, but that’s why tails tend to be bigger, to generate the same amount of pushing force needed to pitch the plane. Meanwhile that drag from being an object that interacts with the air stream is still there. In fact with that combination of being just as present to the air stream and typically larger size due to control demands it could be argued that tails in general generate as much drag as or more drag than canards (to be clear I’m not saying that a plane with tails is always draggier than a plane with canards, as always I dislike drawing hard conclusions about specific designs based on superficial cherry picking of individual features).

I’ve also given this canard stealth thing some thought, and I’m not sure the prevailing conclusions are correct. They sound more like erroneous extrapolations of some laymen heuristics. If we think about how RF backscatter against a wing works, the incidence angle the wave encounters is what determines their angle of reflection. Against a plane’s surface this is determined by sweep angle, which is true for both the canard and wing. If their sweep angles match they should be reflecting the RF wave in the same direction. In this sense the general amount of RF energy reflected back to the source for a canard surface is at most a linear addition to the amount reflected back by the wing when the canard edge doesn’t block direct line of sight to the wing, and a non contributor in the general sense when the canard edge is coplanar to the wing edge, at least in terms of total energy. This may mean that in terms of total possible energy a canard+wing is reflecting the same amount of total energy as a larger wing, as more surface always equals more energy reflected, but when that is the case the extra contribution of surface from a canard, like with a larger main wing, shouldn’t be noticeably significant because backscatter depends on *area*, and edges for small surfaces don’t have a lot of that, and in addition that area is *effective* area, which isn’t defined by physical dimensions alone but by how reflective the physical object is to the RF wave, which should be much less for surfaces treated to dampen RF reflection.

Despite all that, the typical argument against using canards comes in three flavors. The first is that as an additional object exposed to the RF wave canards will generate their own dipole lobe (the beam of RF energy reflected away from the source) separate from the wing. However, so long as the canard shares the same sweep as the wing the angle of their dipole lobes will be the same, which is to say they should be reflecting RF energy in the same direction, which then therefore means the canard’s extra dipole lobes shouldn’t disrupt the “bowtie” shape generated by the wing to forward facing RF waves. A canard with the same sweep as the wing should therefore at worst only have negligible extra contributions to frontal RCS, and at best make no difference (with the dipole lobe of the canard being totally indistinguishable from that of the wing and the rest of the fuselage), except when extra exposed edges contribute some extra area for the RF wave to interact with, which itself should be minuscule for treated surfaces.

The second kind of argument is the traveling wave problem, where as a function of being in front of the main wing the traveling wave that propagates along the canard’s surface exits from the canard’s trailing edge and interacts with the main wing in a more scattered fashion, which makes that portion of RF reflection more difficult to control. If the canard is either reflecting or dampening most of the RF energy hitting it though the additional contribution of RF energy propagated to the portion of the wings behind the canard should be quite small, smaller still if that portion of the wing is treated to dampen RF reflections, and even smaller if the canard also has their trailing edge treated to dampen RF reflections. Furthermore, the angle at which those traveling waves are reflected once they exit the trailing edge may be effectively controlled by metamaterials to reflect that energy in a more favorable direction and further limit their interactions with the main wing. In the J-20’s case, the canards being angled at a dihedral rather than being coplanar may actually help reduce this component of RF reflection. The trade off is of course more of the wing edge behind the canard is exposed, so you get that linear addition I mentioned earlier, but again that may end up being negligible.

The last kind of argument is that the canards, by adding an extra wing root, adds an additional corner reflector. In the J-20’s case though the canard wing root is coplanar with the main wing, so there should only be one corner reflector facing forward. Of course all these arguments apply strictly to forward facing RF waves. For azimuths that look more sideways or vertically, canards may actually be a bit better than horizontal surfaces, since at those angles line of sight to the tails aren’t being blocked by the main wing, and tails tend to be much larger than canards.
 
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Tam

Brigadier
Registered Member
and here you are 180 degrees out of phase with the real world of aerodynamics, canards are always making positive lift, (a good thing), and in the process making drag! (a bad thing), so the canards are inherently more "draggy" than the tail feathers. Now while the canards are making more lift, they are in "clean air" and are likely more effective per size and moment arm than tail feathers which reside in "dirty air"?

you correctly assert that the main wing is able to "mask" the tailplanes, while the canards are standing out front.... (they may "mask" a portion of the main wing head on, but at more oblique angles, not so much), they will likely raise RCS from the frontal and possibly side angle.

the J-20 does not have "all moving" tailfins, the F-22 does have all flying stabilators, which are also used to roll the aircraft

in the end, its six of one, half a dozen of the other, both arrangements have strengths and weaknesses.


Tailplanes would require a greater angle of attack to achieve the same control authority as canards, the larger surfaces of the tailplanes and the greater angles of attack can mean more drag during a turn. Tailplanes push the rear of the plane to pitch up the plane, whereas canards simply pull the nose up to pitch. Due to the movement of the tailplanes and the ailerons for roll, from the rear aspect, the tailed aircraft risks a greater RCS when facing a pursuer. Like you said both arrangements have their strengths and weaknesses.
 
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