J-20 5th Gen Fighter Thread IV (Closed to posting)

[latenlazy]

Oh my. Did not realize the length of time it took me to write that loonnnggg entry the discussion had already moved on. Well anyways, maybe the mods should move my entry (to that defunct aerodynamics thread?) if they feel it would de-rail what is clearly the more important task of this thread (admiring updates on 2011).

 

[chuck731]

Hmmmm... I thought that was one of advantages of the Chinese fighters, which all have been designed to optimize maneuverability...

There are different type of maneuverability. The most versatile and effective type of maneuverability in air combat is energy maneuverability. Energy maneuverability requires the ability to in moving to and from combat, and having high thrust to weight ratio in combat. This in turn puts a premium on engine performance.

Here china has been and remains behind.

In the 1950s, Chinese favored agility with its fleet of mig 15, 17 and 19 in confrontations with American pilots in Korea and with American trained pilots over Taiwan strait. Agility is different from maneuverability. Agility is the ability of an aircraft to rapidly change its heading. Maneuverability is the ability of an aircraft to rapidly move between different altitudes and locations in the battlefield. And agile aircraft might turn in a very small circle. And maneuverable aircraft might turn in a big circle, but it can complete the circle in less time than an agile aircraft. And agile aircraft might break left and then break right in a split second. And maneuverable aircraft might not go from the one to the other as quickly, but can cover more distance to the left or right more quickly once it has braked. An agile aircraft might pull out of dive and enter a climb very quickly. But an maneuverable aircraft can gain or lose altitude much more quickly.

By the late 1960s, fighter designers have done comprehensive studies of all the air-air combat victories ever recorded. They came to a startling conclusion, which is between two situationally aware pilots maneuverability trumps agility every time. An skilled and alert pilot in an agile aircraft can only some times avoid getting shot down, but always has little chance of shooting down a skilled and alert pilot in an maneuverable aircraft. A skilled pilot in an maneuverable aircraft on the other hand, can usually shoot down a skilled pilot in a agile aircraft. Furthermore a pilot in a maneuverable aircraft is much more likely to catch a pilot in a agile aircraft unaware than the other way around. Being caught unaware by the opponent who is gunning for you turned out to be responsible for more than half of all losses in combat between fighters.

So all fighters designed since 1970s has emphasized maneuverability over agility of the sort the Chinese PLAAF had believed to be critical during air battles over Taiwan straits in the 1950s.

 

[latenlazy]

There are different type of maneuverability. The most versatile and effective type of maneuverability in air combat is energy maneuverability. Energy maneuverability requires the ability to sustain high speed and results from high fuel efficiency at high speed in moving to and from combat, and high thrust to weight ratio in combat. This in turn puts a premium on engine performance.

Here china has been and remains behind.

I've realized that it makes little sense to caveat the J-20's performance on engines. The J-20 will eventually get an appropriate engine. If the WS-15 fails, they will do what they need to to import from Russia, but either way eventually the J-20 will get the thrust it needs.

 

[chuck731]

I've realized that it makes little sense to caveat the J-20's performance on engines. The J-20 will eventually get an appropriate engine. If the WS-15 fails, they will do what they need to to import from Russia, but either way eventually the J-20 will get the thrust it needs.

Well, unfortunately engine makes the plane. So no good engine means mediocre plane. It is also unclear whether the Russians themselves are really still competitive with the real current state of the art. The Russians themselves have yet to demonstrate an fully developed engine in the class of WS-15, or F-119. Current state of the art in the US is undoubtedly well on its way to a generation beyond F-119.

 

[latenlazy]

Well, unfortunately engine makes the plane. So no good engine means mediocre plane. It is also unclear whether the Russians themselves are really still competitive with the real current state of the art. The Russians themselves have yet to demonstrate an fully developed engine in the class of WS-15, or F-119. Current state of the art in the US is undoubtedly well on its way to a generation beyond F-119.

The common reason why people keep on mentioning engines with the J-20 is because people are skeptical of China's engine industry and it's maturation. People don't commonly exhibit the same skepticism of the T-50s engines because it's commonly believed that Russia will actually get their appropriate engine and because what they lacked was time and resources, not know how and capability.

I have no doubt the US is well on its way to the next generation of engines, but it's unclear when that will actually be put into operation, which is dependent on when they develop their next generation of fighters. Right now the US has its own impediments to continuing its technological superiority, mainly in terms of development cost and political and strategic indecision. Meanwhile we know China is pursuing parallel development to try to reach parity, and this is likely the case with Russia as well. In short, I agree about the US's advantages, but it's not baked in the cake by a mile.

 

[chuck731]

The common reason why people keep on mentioning engines with the J-20 is because people are skeptical of China's engine industry and it's maturation. People don't commonly exhibit the same skepticism of the T-50s engines because it's commonly believed that Russia will actually get their appropriate engine and because what they lacked was time and resources, not know how and capability.

Their assessment is not unreasonable. But they miss the fact that while Russian capability and know how is a wasting asset, Chinese capability and know how is a growing asset.

The question is would Chinese capability and know how grow at a fast enough pace to achieve parity with the US in the foreseeable future.

 

[latenlazy]

Their assessment is not unreasonable. But they miss the fact that while Russian capability and know how is a wasting asset, Chinese capability and know how is a growing asset.

The question is would Chinese capability and know how grow at a fast enough pace to achieve parity with the US in the foreseeable future.

Exactly. Personally I'm reasonably confident it would for a number of student reasons.

 

[Air Force Brat]

I think 2011 is, if not the first low rate production model, at least a development airframe with stealth treatment very close to currently intended production configuration. So it has all the external stealth shaping to be found on the production aircraft.

2001 and 2012 are clearly less refined in stealth shaping, and show not strong evidence of stealth treatment in areas such as joints of leading edge flaps and underwing actuators.

I would agree completely, though I am hesitant to refer to 2011 as LRIP, I do think it is, or is very close to the configuration of the production aircraft, now if CAC decides to go with concurrent development/production, you may very well be right. As more and more detailed pictures come out, with each of you seeming to find a few new things everyday, I suddenly was taken by the overall shape and design, CAC has gone after the details small and great, this airplane obviously tweaked all over, obviously the flight test data has been "mined" very deeply for any potential draggy, or areas where L/O was compromised, very good post chuck. brat

perhaps one of you organized/bright lads could "catalogue" these changes as Deino has done with the platform silhouette, this gives us an idea of the very serious commitment to get this airplane right, I expect to see the "bossman" himself visit CAC very shortly, much as we saw him give an official blessing to CV-16 and the J-15.

 

[Engineer]

So all fighters designed since 1970s has emphasized maneuverability over agility of the sort the Chinese PLAAF had believed to be critical during air battles over Taiwan straits in the 1950s.

If we use your definition of agility as quick nose-pointing ability and maneuverability as the ability for an aircraft to circle behind an opponent, the case with China is quite opposite to what you have claimed. Take the J-10 as an example, China could have import thrust vectoring engines from Russia to improve the aircraft's agility. Instead, China is content with not having thrust-vectoring even with the J-10B. For the J-20, Song Wencong's paper emphasizes lift rather than quick noise-pointing ability, and lift is what gives an aircraft good maneuverability.

 

[Air Force Brat]

Oh my. Did not realize the length of time it took me to write that loonnnggg entry the discussion had already moved on. Well anyways, maybe the mods should move my entry (to that defunct aerodynamics thread?) if they feel it would de-rail what is clearly the more important task of this thread (admiring updates on 2011).

Actually, I found your post very helpful and accurate, maybe a little too honest for the taste of some, but I appreciate the thoughtful "cogitations". To relegate that to a defunct post would be a tremendous waste. Those thoughts on energy management are very cogent to understanding just where this aircraft "fits", it appears that you are beginning to get a feel for this airplane that many never will, and may not appreciate, your observations and reflections reveal the depth that Dr. Song has aspired to incorporate into this airplane, he would be proud. brat