Chengdu J-20 5th Generation Aircraft News & Discussions

[razgriz19]

MAIN WEAPON BAY OPEN!!!!!!!!!!!!!!!!!!!!!

 

[razgriz19]

J-20 pulling and rolling!

???J20??????_?_?_?_

 

[siegecrossbow]

J-20 pulling and rolling!

???J20??????_?_?_?_

You are way too late on the action bro... We've seen that a hundred times at least...

 

[razgriz19]

You are way too late on the action bro... We've seen that a hundred times at least...

i had a feeling it was posted here before.......but my friend sent it to me so i just posted incase anyone missed it

 

[Martian2]

J-20 Mighty Dragon has canard winglets, but no tailplanes.

F-22 Raptor has no canards, but it has tailplane winglets.

From a stealth design perspective, there is no effective difference between placing two little winglets (i.e. canards) in front of the main wings or behind them (i.e. tailplanes).

However, from a maneuverability standpoint, the J-20 Mighty Dragon canards provide it with super maneuverability. The F-22 Raptor tailplanes merely provide stability. This is understandable because the F-22 is a much older design. Aerospace engineers have a better understanding of stealth design today than twenty years ago.

In conclusion, the J-20 Mighty Dragon is a superior evolutionary design of its chronological F-22 predecessor.

[Note: Thank you to HouShanghai and Feiyang for the J-20 picture.]

 

[gambit]

J-20 Mighty Dragon has canard winglets, but no tailplanes.

Big deal.

F-22 Raptor has no canards, but it has tailplane winglets.

From a stealth design perspective, there is no effective difference between placing two little winglets (i.e. canards) in front of the main wings or behind them (i.e. tailplanes).

Utter garbage. From a radiation generator perspective, the more generators there are on a non-spherical complex body, the greater the odds of detection. This is established fact. Real physics, not Chinese physics.

However, from a maneuverability standpoint, the J-20 Mighty Dragon canards provide it with super maneuverability. The F-22 Raptor tailplanes merely provide stability. This is understandable because the F-22 is a much older design.

Older does not mean obsolete or inefficient and canards are nothing new.

Aerospace engineers have a better understanding of stealth design today than twenty years ago.

Does not mean every country can design the same.

In conclusion, the J-20 Mighty Dragon is a superior evolutionary design of its chronological F-22 predecessor.

Bunk. It is telling that you consistently demand 'extraordinary proofs' from others but equally consistently refused to provide your own.

 

[ptldM3]

From a stealth design perspective, there is no effective difference between placing two little winglets (i.e. canards) in front of the main wings or behind them (i.e. tailplanes).

We went through this before.

However, from a maneuverability standpoint, the J-20 Mighty Dragon canards provide it with super maneuverability. The F-22 Raptor tailplanes merely provide stability. This is understandable because the F-22 is a much older design. Aerospace engineers have a better understanding of stealth design today than twenty years ago.

The notion that canards are a one and all solution to maneuverability is a myth. Yes canards usually improve an aircraft's AoA, however, with today's advances in fly-by-wire, TVC engines, and high trust-to-weight ratios canards are, dare I say, obsolete or overshadowed. This is one of the reasons the SU-35 did away with canards, that and a reduction in RCS, but from a maneuverability stand-point the SU-35 can do everything that an SU-30 with canards can, if not better.

 

[gambit]

The notion that canards are a one and all solution to maneuverability is a myth. Yes canards usually improve an aircraft's AoA, however, with today's advances in fly-by-wire, TVC engines, and high trust-to-weight ratios canards are, dare I say, obsolete or overshadowed. This is one of the reasons the SU-35 did away with canards, that and a reduction in RCS, but from a maneuverability stand-point the SU-35 can do everything that an SU-30 with canards can, if not better.

Here is where these guys totally missed the point: The ANALOG version of the F-16 wildly succeeded was because of the highlighted combination. High thrust-to-weight ratio enabled the F-16's FLCS to create greater displacement of the rear horizontal stabs at greater rate of displacement.

Greater displacement and greater RATE of displacement.

Our engine technology made canards unnecessary. Because of its ability to reach its limit of 25.5 deg AoA and the rate of that change, the F-16 needed that outsized vertical stab because as AoA increases so does the fuselage's ability to block airflow to that axis. With the F-22's 2D vectored thrust and power, canards are totally worthless.

 

[Black Widow]

However, from a maneuverability standpoint, the J-20 Mighty Dragon canards provide it with super maneuverability. The F-22 Raptor tailplanes merely provide stability. This is understandable because the F-22 is a much older design. Aerospace engineers have a better understanding of stealth design today than twenty years ago.

Original Post By Martian2

Food for Thought:


Just open the old thread of PAK-FA. Many expert from Pakistan and China questioned PAK-FA LREX. Some of the radar/stealth experts even claim that LREX of PAK-FA can contribute 1 m2 to RCS. Now when chinese J20 has cancard, there tone is changed...




@Topic: What I believe is , if Russia or chines are making 5th gen fighter, they will definitely come with 5th gen fighter. By passing such comments (J20/PAK-fa will less stealthy than F22) We are insulting the engineers, or boosting our ego..

 

[gambit]

Food for Thought:


Just open the old thread of PAK-FA. Many expert from Pakistan and China questioned PAK-FA LREX. Some of the radar/stealth experts even claim that LREX of PAK-FA can contribute 1 m2 to RCS. Now when chinese J20 has cancard, there tone is changed...

Hold up a sec...

In edge diffraction of movable bodies, there are three areas of interests: leading edge, trailing edge, and end. Remember, these are finite bodies that made up the greater finite body called 'aircraft'.

A canard has all three of those points of interests. The T-50's movable leading edge root extension has two: leading edge and end.

The more radiation generators, the greater the odds of detection.

 

[S10]

We went through this before.




The notion that canards are a one and all solution to maneuverability is a myth. Yes canards usually improve an aircraft's AoA, however, with today's advances in fly-by-wire, TVC engines, and high trust-to-weight ratios canards are, dare I say, obsolete or overshadowed. This is one of the reasons the SU-35 did away with canards, that and a reduction in RCS, but from a maneuverability stand-point the SU-35 can do everything that an SU-30 with canards can, if not better.

An insider from CAC had already revealed in the past that the J-20 requirment for AoA alpha was 80 degree without the use of thrust vectoring. That eliminated all conventional designs from the start.

 

[S10]

Food for Thought:


Just open the old thread of PAK-FA. Many expert from Pakistan and China questioned PAK-FA LREX. Some of the radar/stealth experts even claim that LREX of PAK-FA can contribute 1 m2 to RCS. Now when chinese J20 has cancard, there tone is changed...

What experts? Show me one legit source that Chinese "experts" made such assertions. No, Martian2 doesn't count as one.

 

[ptldM3]

An insider from CAC had already revealed in the past that the J-20 requirment for AoA alpha was 80 degree without the use of thrust vectoring. That eliminated all conventional designs from the start.

There is a number of conventional aircraft (no canards and no TVC) that can acheive a 90+ degree A0A, so your statement about conventinal designs needing to be eliminated in order to acheive such an A0A is not true.

 

[gambit]

An insider from CAC had already revealed in the past that the J-20 requirment for AoA alpha was 80 degree without the use of thrust vectoring. That eliminated all conventional designs from the start.

Let us take that at face value. It can begs the questions:

- Were there any justifications for that requirement?

- Achieving such AoA does not equate to controllability at such high AoA.

This does not mean that if sometime in the future China is able to produce a durable thrust vectoring engine, achievable AoA and associated controllability is doubled. What this implies is that the J-20 may be 'stuck' with the current engine configuration.

Here are the advantages and disadvantages of canards:

Canard Advantages and Disadvantages

Finally, and perhaps most importantly, canard sizing is much more critical than aft tail sizing. By choosing a canard which is somewhat too big or too small the aircraft performance can be severely affected. It is easy to make a very bad canard design.

As far as RCS contributorship goes, aeroelasticity is a factor...

Aeroelasticity - Wikipedia, the free encyclopedia

Aeroelasticity is the science which studies the interactions among inertial, elastic, and aerodynamic forces. It was defined by Arthur Collar in 1947 as "the study of the mutual interaction that takes place within the triangle of the inertial, elastic, and aerodynamic forces acting on structural members exposed to an airstream, and the influence of this study on design." In more simple terms, it is the same set of conditions causing a flag to flutter in a stiff breeze or a reed to tremble in fast-flowing water. Flutter may occur in any fluid medium.

The dominant aeroelastic form in the canard is flutter and as an active flight control element, this effect increases the RCS contributorship of these flight control elements. Discussions about this effect can be found at 'canardaviation.com'. But as far as unpredictable EM edge diffraction effects goes, fluttering of any structure is detrimental to the overall RCS, especially when there are 'downstream' structures like the fuselage and the main wings to surface propagate and possibly amplify these signals.

 

[S10]

There is a number of conventional aircraft (no canards and no TVC) that can acheive a 90+ degree A0A, so your statement about conventinal designs needing to be eliminated in order to acheive such an A0A is not true.

To my knowledge, there is not a single operational fighter plane, without TVC, that can achieve achieve 80+ degree controllable AoA. Even the F-18 HARV with thrust vectoring was roughly in the same ballpark.

Note: I rechecked his statement. It was 90 AoA without the use of thrust vectoring.

Let us take that at face value. It can begs the questions:

- Were there any justifications for that requirement?

- Achieving such AoA does not equate to controllability at such high AoA.

This does not mean that if sometime in the future China is able to produce a durable thrust vectoring engine, achievable AoA and associated controllability is doubled. What this implies is that the J-20 may be 'stuck' with the current engine configuration.

1. You will have to ask PLAAF for their justification.

2. He said "90度可控", meaning 90 degree controllable.

Like I said before, China uses the "4S" requirements for its 5th gen fighter program. Stealth, Super-manoevurable, Supercruise and Sensor fusion are all part of it. However, some requirment have higher priority than others. For China, supermanovurability and supercruise are the most paramount. Not my words, but the words of the guy working for the design bureau.

There had been an assortment of academic journals from two Chinese universities that specialize in aviation regarding blending the canard with a LO design. They also conducted tests in anechoic chamber belonging to Chinese space agency, and the military was satisfied of the results. I trust them to know what they're doing.