Chengdu J-20 5th Generation Aircraft News & Discussions

[gambit]

Sigh! The canards negatively affect stealth, that's why they are a source of heavy criticism...

Canards have an adverse contributorship to low radar observability compared to other structures on an aircraft whose intention is towards being low radar observable. Get your phrasing straight, neophyte.

...and the reason this idea of a canard stealth mode in the FBW even began.

It is an idea not worth the blood sugar spent in speculating about.

Your contention is some back-assward logic that the canards were put there to control negative stability rather than for any other reasons.

Prove me wrong.

Prove me wrong that WW I era bi-planes were practically negative stability designs...

Elevator - Wright 1903 Flyer

The Wright flyers were highly maneuverable but not very stable. The brothers had to constantly provide the stability for the aircraft by working the flight controls to change the elevator setting. Like the Wright 1903, modern fighters are also designed to be highly maneuverable but not very stable. Fighters now use a computerized stability augmentation system (SAS) to reduce the work load on the pilot.

You, like the rest of the Chinese neophytes, confused stability with aerodynamics.

The Wright Flyer had canards and was not very stable. WW I bi-planes were practically negative stability designs themselves. So prove me wrong in post 1740 that we have ALWAYS have negative stability flight experience, especially when the Wright brothers over one hundreds years ago experienced it WITHOUT FLY-BY-WIRE technology. What 'other reasons' are there if not for the allowance of safe entrance into the negative stability flight regime, stay there, and have effective controls of the aircraft at all times?

Like I said, you lack tactical and strategic foresight and cannot conceive that there is a time, place and reason for everything. This is called "Strategy"...

strat·e·gy/ˈstratəjē/
Noun:

1. A plan of action or policy designed to achieve a major or overall aim.
2. The art of planning and directing overall military operations and movements in a war or battle.

When you made one serious technical blunder after another, failed to recognize your error, refused to admit ignorance, and continues to repeat the same cycle in the face of unimpeachable sources that proved you wrong......I hope ALL Chinese generals and admirals take after you.

Yet another red herring, surprise! surprise! Fyi, your declaration that the canards are there only to compensate for negative stability is your personal guess and something you just threw in there so you can claim the canards function cannot be compensated whatsoever by the other control surfaces. All the control surfaces work together and the other control surfaces could compensate for less "severe" angling of the canards and vice-versa.

And yet I managed to find far more evidences to support my 'guess' than you have for yours -- that these flight control elements can be made selectively active at the flick of a switch at the pilot's convenience.

More stuff for you and the Chinese boys to learn how ignorant and foolish your arguments really are...'control effectors'...

IEEE Xplore - Reconfigurable flight control for UAV with multiple control effectors based on neural network and dynamic inversion

A reconfigurable flight control based on a single hidden layer perception (SHL) neural network (NN) for adaptive compensation of dynamic inversion for the Unmanned Aerial Vehicle (UAV) with multiple control effectors is described. This approach has not to depend on failure identification and isolation. The basic control law is designed by nonlinear dynamic inversion, and SHL neural networks are used to eliminate the inversion error due to parameter uncertainty, disturbance, control effectors' failure, etc. The simulation results indicate that SHL NN can eliminate the inversion error adaptively and properly, and this reconfigurable flight control method can improve the robustness of the system when the control effectors' failure occurs.

Whenever there is an item that have at least two degrees of movements in 3D space and that it has a direct effect on an aircraft's attitude, it is call a 'control effector'.

Title page for ETD etd-072299-150703

A comparison of two control allocation methods is performed utilizing the F-15 ACTIVE research vehicle. The control allocator currently implemented on the aircraft is replaced in the simulation with a control allocator that accounts for both control effector positions and rates. Validation of the performance of this Moment Rate Allocation scheme through real-time piloted simulations is desired for an aircraft with a high fidelity control law and a larger control effector suite.

Look at the description:

The F-15 ACTIVE had nine control effectors: left canard, right canard, left aileron, right aileron, left stabilizer, right stabilizer, rudder (two surfaces counted as one effector since they move together), pitch nozzle, and yaw nozzle.

Flight control surfaces totaled 7, so what account for the other 2?

NASA - ACTIVE Home Page - Thrust vectoring technology

Encoded in the ACTIVE dataset is the selection of: 1) either the Programmable Test Input (PTI) or AdAPT research control law mode, 2) aerodynamic or propulsion control effector commands,...

You read that right, kid. Thrust vectoring qualify as a 'control effector'. Pitch and yaw thrust vectoring for the F-15 ACTIVE were 'control effectors'.

The F-22 have these 'control effectors': left and right flaperons, left and right stabilators, rudders, and pitch (only) TVC. Total of 6. The F-16 have these 'control effectors': left and right flaperons, left and right stabilators, rudder. Total of 5. Fixed ventrals do not count because they are fixed and therefore provide only single direction stability. Control effectors are for attitudinal changes.

Now that we established that I do not make sh!t up but actually have relevant experience to debate and to back up my arguments with credible sources, the reality is that the more 'control effectors' you have, the better the flexibility you have to increase maneuverability at greater ranges of airspeed and AoA. The greater the flexibility you have the greater the demand upon you to provide the necessary flight control laws to exploit this flexibility. Conversely, if you have poor programming skills, then all the flight control effectors doo-dads in the world are not going to help you. High maneuverability, especially at low aerodynamic forces (low speed), require as many 'control effectors' as you can bring, and whatever you have should be able to deflect as wide a margin as you can afford, hardware and software.

The J-20 -- without TVC -- have the same amount of 'control effectors' as the F-16. Canards are 'control effectors'. Limiting their movements in the hope -- HOPE -- of minimizing their RCS contributorships is asking for an in-flight disaster. That is like US reducing the gains on the F-16's tail horizontal stabilators when entering a high EM environment where possibly the best route may take aircraft to low altitude where there is limited maneuvering room and therefore he is going to need as many 'control effectors' as he have and be able to use them as much as he can.

So by all means, just to satisfy the Chinese boys and their fan club, it is technically feasible for the J-20 to 'lock' the canards in place when in a high EM threat environment. And I do hope the Chinese DO NOT exercise technical and operational common sense when they do give the J-20 this 'feature'. ...It will make the Americans' -- and possibly the Indians' -- job easier at shooting the PLAAF out of the sky.

You then incorrectly and purposely quote a bogus accusation that I said the canards should be locked in place for such a FBW mode, something that is patently false and already proven false by message #1725. Like I've already said, you lack integrity and constantly resort to lies and deceptive use of out-of-context minutiae.

Did I? That 'locked into place' comment was from post 1630. Even though it is not yours, the fact that you subscribe to the same reasoning made it irrelevant. And I never quoted you anyway, I only used the word to describe BOTH of you guys' arguments.

Fyi, the primary reason the J-20 has canards is because it was designed by CAC. Chengdu's primary strength where it is most experienced is with the delta canard layout with its most advanced fighter aircraft being the delta canard J-10B. The same developmental evolution is present with the PAK FA as derived from the family lineage of Sukhoi Flankers. If stability was the issue, the J-20 could simply have used a small LERX instead of having the delta wing so far back and using a canard. You quoted 10 pages of minutiae for a simple solution that could be summarized in 1 sentence Einstein. lol

Here is where you clearly did not understand my post 1740.

The issue is not stability, or more precisely negative stability, the issue is which METHOD to maintain controlled flight when the design is with deliberate negative stability. You already demonstrated you know zilch-o when it comes to aviation related subjects and whatever you chose to speak about -- thereby making a fool out of yourself -- you leaned on fellow ignoramuses, like the guy who used 'Chinese physics' to call the IRST device 'not stealthy' but the left the much larger canopy as 'stealthy'. So upon what foundation do you stand upon to say declare that so-and-so could have use an alternate method? But if they did, the final product would not be the current J-20 under discussion, would it? The fact that the J-20 is 'what it is' made those alternate methods irrelevant. Might as well be discussing another aircraft.

Finally, am going to give one last chance to make at least a feeble attempt at salvaging your face. Let us grant that the J-20 have this canard 'stealth' mode, which of these other 'control effectors' is/are the best candidate to make that speculative 'compensatory' movements to maintain controlled flight while the canards are 'locked' or have their gains reduced: The rudders or the flaperons?

 

[conworldus]

And YOU do? I have yet to see anything remotely edukashional from you. But then again, I do not major in 'Chinese physics'.

I don't and I don't pretend. You are nothing more than a copy and pasting zombie, plus a bit racism being an Indian.

 

[ptldM3]

I don't and I don't pretend. You are nothing more than a copy and pasting zombie, plus a bit racism being an Indian.

So you accuse someone of being racist on the grounds of their supposed nationality? What i find ironic is that your own racism has just manifested.

 

[j20blackdragon]

In the real world things aren’t decided by looking at them, especially not by clueless Chinese adolescent girls. I will hold my trust in engineers not in what comes out of your mouth. The frontal area of any aircraft always presents the smallest RCS. The biggest contributors to an aircraft’s frontal RCS would likely be the cockpit and engines, with a treated canopy and shielded compressor face those two factors are now resolved. It’s also no surprise that the pylons were removed, canon hidden, and a number of other subtle changes made.

And since Chinese adolescent girls love to point out size as a factor, the F-15 is noticeably smaller/more narrower than the F-35. Essentially the F-15 is not much different from a frontal perspective when compared to the F-35, with minimal differences such as nose, and ‘serration’ other than that many of the same features and techniques that are found in the F-35 are also found in the F-15.

I have two requests:

1. Show me a single example in which Boeing compares the frontal RCS of the F-15SE to the US military version of the F-35, not the international release version.

2. Prove to me that an international version of the F-35 (with degraded stealth) even exists.

Back it up with some links.

Jim Albaugh, who heads Boeing's defense business, told reporters in Paris on Sunday that the new F-15 offered a comparable level of stealth capability to what Washington was willing to sell to foreign military sales customers.

"We are not trying to say that this is an airplane that has full-aspect stealth capability," Albaugh said. "It doesn't. But from a front-radar cross-section, it has all the stealth that has been approved for export by the U.S. government."

AIRSHOW-UPDATE 1-Pentagon F-35 chief blasts Boeing comments | Reuters

Boeing has backed down from previous statements comparing the frontal-aspect radar cross-section of the F-15SE to an international release standard for the F-35.

However, Jones confirms that Boeing's original briefing chart - claiming the F-15SE provides frontal-aspect stealth offered by fifth-generation fighters - remains accurate.

Boeing unveiled the F-15SE in March 2009. The redesign adds conformal weapons bays, stealth techniques, fly-by-wire and canted tails to the F-15E configuration, providing a "first-day-of-war" stealth capability.

Lockheed and F-35 programme officials, however, have criticised Boeing's assertions that the F-15SE offers equivalent front-aspect stealth as the JSF, and denied that an international release standard exists for F-35 stealth characteristics.

Boeing applies to export F-15SE to South Korea

 

[amalakas]

I have two requests:

1. Show me a single example in which Boeing compares the frontal RCS of the F-15SE to the US military version of the F-35, not the international release version.

2. Prove to me that an international version of the F-35 (with degraded stealth) even exists.

Back it up with some links.



AIRSHOW-UPDATE 1-Pentagon F-35 chief blasts Boeing comments | Reuters



Boeing applies to export F-15SE to South Korea

I am sorry, don't you just prove ptldm3's argument with what you just quoted ?

 

[j20blackdragon]

 

[ptldM3]

I am sorry, don't you just prove ptldm3's argument with what you just quoted ?

Yes he did, he also posted a link by Lockheed that acknowledged that the F-15SE does indeed have the same frontal RCS as the F-35. However, in that link Lockheed confirmed that the F-15SE is only comparable to the F-35 from the frontal aspect.

I also explicitly said export version of F-15SE, I guess Black Dragon has a short memory span. Here is that link he asked for:

PICTURES: Boeing unveils upgraded F-15 Silent Eagle with fifth-generation features

 

[TalkToMe:D]

Isn't the plane in the first picture a F-22 ?

 

[Zabaniyah]

Isn't the plane in the first picture a F-22 ?

Yes it is.

 

[yyetttt]

F-22 is the best stealth plane ever. I have to admit, nothing comes close to it.

Not PAK FA, nor J-20.

 

[ChineseTiger1986]

Finally, the production capability of the WS-10 family has been largely increased and WS-15 is nearly ready.

 

[SinoChallenger]

^ I'm confused. This is from Shenyang Liming? I thought WS-15 is the responsibility of the Chengdu engine company?

 

[pakje]

^ I'm confused. This is from Shenyang Liming? I thought WS-15 is the responsibility of the Chengdu engine company?

I'm pretty sure there's some overlap between the 2 companies

 

[marshall]

You have not showed where is that 'contradiction'. Instead, you ended up showing everyone how you and your man are fools. If the IRST device is 'not stealthy', then so is the J-20's canopy since it is much much larger than the IRST device. But since you guys insisted that the ROUNDED canopy is 'stealthy', then how so is the IRST device 'not stealthy' when despite being rounded and much much smaller than the canopy? Your 'logic' does not hold up. This is real physics, not 'Chinese physics'.

The IRST device is not properly stealth shaped. It's a front facing spheroidal shape providing specular reflection back to source. You do not have this with the canopy. That is the difference. The context was talking about the IRST and you brought up the lambda rule suggesting a larger IRST would be more stealthy. The same IRST which you can see is not shaped to deflect radar away from the source and is spheroidal. On an untreated canopy, the cockpit is considered the 2nd worst contributor of RCS and the pilots helmut the worst within the cockpit. Guess what a front facing round IRST most resembles? Hmmm...and you think a BIGGER IRST could be better? Hey, why don't you patent your invention and present it as a stealth breakthrough? LOL

Btw, I've been arguing with that guy for years because he constantly posts questionable stuff. You're simply the flipside of your doppelganger. You and your bloodbrother are Internet cheerleaders to the max.

 

[marshall]

Now that is more stupidity.

It is true that the bi-static radar is 'stealth' greatest threat. But what is not true is that by the '20s such networks will be so widely deployed that it will render 'stealth' worthless. Even so, assuming that speculation -- wild as it is -- is true, then why the hell would the J-20 have canards in the first place given the usual decade long development time from test flight to volume manufacture?

I never said I agree with canards on a stealth airframe. CACs design tradition and strength is with canards. I can only presume it was a trade-off considering the J-20 design began in the late 1990s when China's aeronautics industry was still relatively backwards and couldn't afford the extra development time, especially given that the J-10 only recently began flight testing. That's the most probable reason I can assume for the canards on a stealth airframe, not the maneuverability.

Concerning radar grids, yes it is speculation but it is also probable that this will be an integral part of stealth detection once processing is powerful enough, which just happens to be the main roadblock why multi-modal radars are not effective, YET. If there is enough processing, with an integrated radar grid you can fudge around with the filters to hypothetically find the most stealthy aircraft from 100km+ out. Even L-Band could be used to triangulate position with respectable accuracy IF the processing were there within such a datalinked radar grid.

I don't think the advanced form of what I just described will exist by the 2020s, mostly due to development time, but some form of it will exist since it's already been researched for years and the main thing holding it back is onboard processing+development time. I would presume the radars would mostly be from AWACs and/or battlefield UCAVs as the wingmen of the stealth fighters controlling them from standoff distance all connected with narrow beam datalinks.