J20不是狗斗鸡？Vladimir Karnozov如是说

这有什么，张局还一脸不屑的说T-50是专门研制出来搞飞行表演的JJ，机动好有个P用:D

还真别说，打航母有点靠谱哦

打航母 是第一要务啊

关键是超音速状态下的机动能力

局外人的分析不靠谱。

J20能做到反舰弹内置？或者TG高出了可以内置的扁平的反舰弹？现在说这些也太早了吧

感觉还是很有道理

1、价格昂贵，高空超音速条件下的高机动是鹤立鸡群，但一旦亚音速，会有多少三代飞机追上来格斗？！这样的飞机处于亚音速状态，也就意味着被发现，并在格斗时，做了很大的机动导致速度大大降低；

2、同时我也有一个问题，就是正常条件下，WS15服役的条件下，从低亚音速到1.6M的超音速巡航状态，需要多少时间？如果在很短的时间内可以达到超音速巡航状态，那为什么要过分强调亚音速状态下的机动性呢？

3、那么大的机体，我确实也有点担心亚音速状态下的机动性；

4、但从边条、鸭翼、全动垂危、DSI进气道、可变进气道口等技术来看，这个飞机应该机动性也不太差，我想达到F22的状态应该非常可能。否则就没有必要做那么多启动布局上的优化。否则就没有必要做那么多气动布局上的安排，同时还有一个例证，就是同样有类似布局，但远远没有丝带突出的歼10B，就能不管在亚音速，还是超音速状态，都能够实现高机动性。

总之我个人感觉，这样昂贵的飞机，这样有特殊任务使命的飞机，在亚音速状态进行缠斗，危险性会大大增加，也反而不能体现出自己的战役价值。这样的气动布局只能说是格斗为辅，特殊点穴攻击或制空拦截为主。但为辅的职能，并不意味着其实现这个职能的能力就低。

伯夷叔齐 发表于 2011-2-27 12:54


    亚音速格斗性能应至少不亚于F22
话说回来，三代机想上前，做几个超机动给他一发导弹就完事了....

管他外国人怎么说，四代就是四代

听他们胡扯

从长机身看不太适合格斗。但是从三代以来除了棍子和f16外都不甚强调格斗。f22不也是这样吗？只是不知f35怎样。

T-50 不是隐形机

earthmanme 发表于 2011-2-27 12:50

相比飞机研制，这些都是小儿科，反舰导弹土共有很多，只不过在换个气动外型而已。

只要一超巡，估计三代就是菜，这可是MD自己F15、16的飞行员说的。
注：F22超巡状态下机动可达6G。

天下功夫，唯快不破。

老毛子瞎鸡巴扯蛋。不狗斗成飞把气动设计的这么复杂，放这么多操纵面作甚。

又不是他们造 管他鸟事

毛子怎么不说自己的su27更大更重

和谁狗斗？
三代机面对黑丝，连发现的机会都没有就被秒杀了，除非黑丝的飞飞心情好想玩猫豆老鼠

不狗斗还整什么鸭翼啊

{:jian:}鸭翼是用来做摆设的呢。。。嗯

http://www.flightglobal.com/blog ... imate-aircraft.html
J-20: China's ultimate aircraft carrier-killer?

It's been nearly one month since first flight of the Chengdu J-20, but we still know so little about the aircraft. China's air force -- the PLAAF -- has remained surprisingly mum on an aircraft they were so willing to flaunt on a Chengu runway for nearly three weeks. We still don't know if the J-20 is officially intended as a one-off technology demonstrator or a developmental prototype, although many observers have assumed the latter. We also don't know what the J-20 is designed to do. Is it an interceptor to replace the Shenyang J-8, or a strike bomber to replace the Xian JH-7? Or is it intended to be both or neither?

Frequent Flightglobal contributor Vladimir Karnozov has published a new feature in the Russian language magazine Air Fleet that attempts to fill the contextual vacuum with a thorough aerodynamic analysis. Dissecting three of the J-20's seemingly peculiar characteristics -- center of gravity in relation to the mean aerodyanmic chord, canards in relation to the nose and overly long air intakes -- Karnozov concludes the J-20 is no subsonic dogfighter. In other words, in an acrobatic game of chicken within an F-22 within visual range, the J-20 is dog-meat.

But Karnozov believes the Chinese are no aerodynamic dummies. Rather, he concludes the J-20 has been optimized for a very specific role: a high-speed, intercept-evading, aircraft carrier-killer. In an English translation of the article that Karnozov kindly contributed to The DEW Liine, he writes:

"In my view the Chinese designers optimized their new jet for M=1.4-1.6. Here comes the clue: the J-20 is a missile launching platform able to evade enemy interceptors by means of a high cruise speed. The J-20 may prove a good interceptor -- very possibly. But its main task seems to be anti-shipping: firing missiles at enemy warships while denying their air defense cover."

Read the translated version of Karnozov's full article on the jump.
Chengdu J-20.
China's tool to ram "cheese boxes on rafts".
Vladimir Karnozov
(author's translation of the original text in Russian, published on 12 January by www.aex.ru)

On 11 January 2011 the new Chinese combat jet flew for the first time (in public, at least), taking off at 12:50 local time. The new airplane is referred to as the Chengdu J-20. Chengdu is the name of the city which houses a few aviation industry enterprises, including the aircraft manufacturing plant producing jetfighters and the design house developing them. A few outsiders watched the J-20 fly, as they happened "by chance" to be around the fence of Chengdu factory's aerodrome on that day. The flight itself was uneventful. It took place in the conditions of clear skies allowing photographers to make some good shots.

Before touching down, the pilot made several passes over the runway so as to expose his airplane to the cameras of "aviation admirers" all round the place. Those took photos of the aircraft from different angles and depicted everything they wanted except for doors of internal weapons bays.

These doors were either thoroughly hidden or removed from the shots by the picture takers on the insistence of very competitive advisers. But it is even more likely that these doors were not actually fitted to the J-20 first operable prototype. They are not needed on the very first operable aircraft dedicated to assessment of flight performance, flight envelope, various engine settings, functioning of the essential onboard systems, proving flight control algorithms. As a rule, third or even later prototypes are devoted to weapons testing, but these are yet to be constructed and outfitted.

The J-20 first public flight occurred just in time when US defense secretary Robert Gates was in Beijing on an official visit. Once there, he was trying to calm down the Chinese leaders who were much worried about pending deliveries of modern US-made weapons to Taiwan. Beijing considers this island an essential part of China.

A lot of pictures appeared on the Internet on the memorable day of 11 January. These shots gave more information on the new airplane. In particular, they reveal the shape of the wing and its positioning in relation to fuselage. This makes it possible to make some preliminary conclusions about the aerodynamics layout and technical characteristics of the J-20, and make guesses as to the main task the new jet shall be solving after entering squadron service.

The J-20 represents a relatively large tactical jet with the canards (foreplanes) and large delta wing. The fuselage length is somewhere between 22 and 24 meters, wingspan between 13 and 14 meters. By our estimation the maximum takeoff weight shall be in the region of 40 tons, and operating empty weight twice less than that.

Many aviation experts believe that the J-20 relies on a pair of Russian engines or their Chinese copies. In other words, the J-20's engines are picked out among members of the big family uniting the Item 117, AL-31F, WS-10G and WS-10 Taihang. Two engines together develop in between 30 and 40 tons of thrust. If that is so, then the capability of the propulsion system is enough for supercruise, or supersonic cruise flight at military power (highest power setting without afterburning). We may also expect that the J-20 with restricted fuel and combat load (for instance, when flying air-to-air mission) can fly vertical without losing speed at subsonic regimes and low altitudes.

The viewpoint that the AL-31F family engines power the J-20 is now prevailing. It could well be that J-20 operable prototypes have them in real life. If so, it is a good solution for initial testing, to rely on these well-tried and high-performance power plants. But in future the J-20 may appear with other types of engines. There were reports about China having got hold of the AMNTK Soyuz R-79/79M/179 series engines developed for the Yakovlev Yak-141 and other advanced fighter designs, - these were in development but cancelled for various reason. Ideally, the J-20 should have engines optimized for sustained supersonic flight, and the AL-31F is not such.

When in-flight photos appeared, the J-20 became the hottest topic for discussion among aviation enthusiasts round the world. But as it appeared, the enthusiasts, and even world-famous western journalists, had difficulty in classification of the new Chinese warplane. Is it a superiority fighter? Is it a supersonic bomber? Or, perhaps, it is a multirole, multimode airplane? Even columnists and experts with world's leading aviation magazines have hesitated to give their clear answer to these questions, - that in the view of them having good sources in the US and European intelligence bodies, defense ministries and the industry. It seems that not only journalists, but the professionals were in a state of shock after seeing the new Chinese bird.

First of all, let's determine J-20's center of gravity position. There are some photos available of the J-20 taxiing, in which we can clearly see its long fuselage, wing-to-fuselage connection and landing gears. The J-20 undercarriage is fighter's classics: three-point with a nose gear. And so it makes it easy to determine center of gravity position. To do that we take the main landing gear strut, and attach a line to it starting at the wheel's ground contact point. The line goes up with at an angle of, say, 15 degrees, leaning towards the nose of the airplane. The point where it crosses the fuselage center line is the most likely position for the airplane's center of gravity.

Here comes the first surprise: the likely center of gravity position rests... too far from the mean aerodynamics chord (MAC) of the wing. As a first iteration for aircraft designers, the center of gravity must be somewhere 25-35% of the wing's MAC, - like so is prescribed in the classic aircraft design books.

But the Chinese airplane appears to have the center of gravity position somewhere at MAC's edge. It is fairly strange for a maneuverable fighter, since balancing of the aerodynamic forces and the gravity will require relatively high deflection of the control surfaces - canards in the J-20's case. Should this airplane try to execute high-G maneuvers at subsonic speeds, the deflection of the canards could be a limitation. All this is rather strange for a maneuverable fighter... But not for the J-20, which does not appear to be one of those!

Let's take a look at other available photos, in which the J-20 goes in for landing with landing gear down. Apparently, the canards are set at a rather high positive angle (leading edge upwards), while the wing has its leading edge deflected downwards. The trailing edge surfaces are also deflected down, at rather a small angle. Obviously, at the approach for landing configuration, the wing's center line is highly curved by means of the leading and training edges down, which increases lift (achieved through altering the camber of the wing). But not so much as in the case of the classical flaps.

All this is, again, fighter classics for the delta winged aircraft with foreplanes. And here lies their limitation: the pilot cannot set the trailing edge further down, since the resulting lift force that builds up on the trailing edge will be hard to balance with the canards, in the view of their limited deflection scope (canards may stall at higher deflection angles).

It is well known from the aviation history how to enable delta-winged airplanes to generate more of the lift force at landing. For that purpose the canards are placed as close to the fuselage's nose as possible, to make a larger distance to the center of gravity. For instance, the Tupolev Tu-144 supersonic jet liner had foreplanes that were retracted into fuselage all the time except landing. But Chengdu designers did not do this. Rather, they positioned the canards fairly close to the center of gravity position, and thus sacrificed their effectiveness at landing for some other purposes.

What purposes? Firstly, for non-retractable foreplanes it is important to have them within the supersonic cone as it sets on the top of the airplane's nose at Mach numbers exceeding 1.0. This leads to a conclusion what the Chinese must have been purposely shaping the J-20 for supersonic flying.

Why did the Chinese shape the J-20 that way? Perhaps, they are unfamiliar with the classic solutions for a delta-winged, canard-equipped fighter? No, this is not the case knowing that Chengdu's previous design was the J-10 light weight fighter, now in PLAAF service. On its first public flight, the J-20 was escorted by a J-10B twin seater, the operational trainer version of the baseline J-10 single seat fighter. The J-10 was the star of the Airshow China 2008 and 2010, when it flew superbly with the PLAAF display team pilots at the controls. The J-10 is a very maneuverable airplane. This fact is the testimony of the Chinese designers' skills in development of maneuverable fighter aircraft.

The J-10 is a classic design with "proper" positioning of the center of gravity, like prescribed in the books. This is clear to tell looking at the main landing gear struts attached to the fuselage somewhere near 15-30% of the wing's MAC. So, let us ask ourselves the same question again: why did the Chinese designers shape the J-20 that way?

Here are some suggestions.
First, to achieve smooth airflow with desirable parameters at the entry to the engine's fan, the J-20's designers have to make the air intakes rather long - much longer than those on the F-22A Raptor or Sukhoi T-50 (PAK FA or FGFA). As it was put before, the J-20 prototype is likely to be flying on the AL-31s, but in future it may get a new engine type optimized for sustained supersonic cruise, - and that other engine is likely to be longer and require longer air channels. In any case, long air intakes were an important consideration at the design stage.

Second, the designers also needed to make air channels S-shaped, so as to hide the fan blades from the radio waves emitted by enemy radars. This is needed for a lower visibility of the airplane. It is worth to notice that the J-20's air intakes resemble those on the Lockheed Martin F-35 Lightning II ("diverterless" supersonic inlet, DSI). This gives move ground to assert that the J-20 is optimized for supersonic regimes and supercruise, much like the F-35.

Third, let us make distribution diagram for the airplane's cross section along the J-20's fuselage centerline. We need to take into account the thickness of the wing, canards and empennage. The diagram appears to be very smooth, - exceptionally smooth! It comes without a peak, running smoothly at approximately the same height from the tips of the air intakes all the way to the engine nozzles.

This seems to be the main thing about the J-20. Apparently, the Chengdu designers wanted to make the airplane's equivalent body of rotation as narrow as possible. And they needed to make provision for internal carriage of weapons, which is a characteristic feature of all fifth generation fighters. In actual fact, the J-20 appears to have much smoother cross section distribution diagram than the F-22A Raptor, the F-35 Lightning II and the Sukhoi T-50. Apparently, it required quite an effort from the Chengdu designers and so made them go for compromises on other things.

Should the Chendgu designers have made it "classic", they would not have moved the wing all the way towards the engine nozzles. But they did because it was the only effective way to make the airplane's body of rotation as narrow as possible, with the need for big air intakes, air-supply channels and internal weapons bays.

Again, this is the main thing about the J-20 design, and it sets it apart from all other known fifth-generation fighters. Other designs have "peaks" some 55-70% down the way from the fuselage nose tip to the engine nozzles (for the Su-27 family aircraft the respective figure is 55-60%, depending on version).

A smooth cross section distribution diagram is important for transonic drag. Supersonic aircraft are being designed in accordance with so-called "area ruling". For high Mach numbers (M>2) the distribution diagram is not that important as for the transonic regimes, M=1...1.5. It seems the Chinese designers optimized their new jet for transonic regimes and moderate supersonic speeds.

A huge effort on proper shaping of the Su-27 was made by Sukhoi designers in cooperation with TsAGI in order to improve its transonic performance. Three TsAGI's big wind tunnels, the T-112, T-108 and T-109 were used in the process. As a result of very accurate optimization of the fighter's cross section distribution diagram, the Su-27's "wave drag" was reduced by 25% - not before the designers virtually redeveloped the airplane (the initial aircraft was referred to the Su-27, the improved version became known as the Su-27S).

My impression from the J-20 is that it is an uncompromised airplane for supercruise, for flying at moderate supersonic speeds corresponding to Mach M=1.4-1.6. Such speeds can be achieved without afterburning. Surely, the J-20 can accelerate to M=2 and faster, but this would require engaging afterburners. In turn, the fuel burn will go high, lowering operational range of the aircraft and enlarging its heat signature.

In my view the Chinese designers optimized their new jet for M=1.4-1.6. Here comes the clue: the J-20 is a missile launching platform able to evade enemy interceptors by means of a high cruise speed. The J-20 may prove a good interceptor, - very possibly. But its main task seems to be anti-shipping: firing missiles at enemy warships while denying their air defense cover.

One day it may happen that the new Chinese jets would be used in anger. On such a day People's Liberation Army would order its pilots to attack enemy warships off the coast of a freedom-loving island not far from the mainland China. In that sense the J-20 is a likely replacement for the JH-7A strike aircraft.

The history of the powerful US Navy can be traced back to the famous duel of the USS Monitor and VSS Virginia (Merrimack) on 9 March 1862, the first-ever battle of ironclads. The USS Monitor, a 987-ton armored turret gunboat, was built at New York, with a large single cannon turret on a low freeboard. Although the Confederacy gunners scored hundreds of direct hits, shells bounced off her armor: the Monitor seemed to have impunity to enemy shellfire. After the battle, the North Americans constructed fifty monitors modeled on their namesake and made them the backbone of their navy. For their rather strange looks, these ships were called "cheese boxes on rafts". Since the memorable Battle of Hampton, the North Americans never lose at sea, and now their cheese boxes sail when and where they want. China prepares a tool to ram them.

http://www.flightglobal.com/blog ... imate-aircraft.html
J-20: China's ultimate aircraft carrier-killer?

It's been nearly one month since first flight of the Chengdu J-20, but we still know so little about the aircraft. China's air force -- the PLAAF -- has remained surprisingly mum on an aircraft they were so willing to flaunt on a Chengu runway for nearly three weeks. We still don't know if the J-20 is officially intended as a one-off technology demonstrator or a developmental prototype, although many observers have assumed the latter. We also don't know what the J-20 is designed to do. Is it an interceptor to replace the Shenyang J-8, or a strike bomber to replace the Xian JH-7? Or is it intended to be both or neither?

Frequent Flightglobal contributor Vladimir Karnozov has published a new feature in the Russian language magazine Air Fleet that attempts to fill the contextual vacuum with a thorough aerodynamic analysis. Dissecting three of the J-20's seemingly peculiar characteristics -- center of gravity in relation to the mean aerodyanmic chord, canards in relation to the nose and overly long air intakes -- Karnozov concludes the J-20 is no subsonic dogfighter. In other words, in an acrobatic game of chicken within an F-22 within visual range, the J-20 is dog-meat.

But Karnozov believes the Chinese are no aerodynamic dummies. Rather, he concludes the J-20 has been optimized for a very specific role: a high-speed, intercept-evading, aircraft carrier-killer. In an English translation of the article that Karnozov kindly contributed to The DEW Liine, he writes:

"In my view the Chinese designers optimized their new jet for M=1.4-1.6. Here comes the clue: the J-20 is a missile launching platform able to evade enemy interceptors by means of a high cruise speed. The J-20 may prove a good interceptor -- very possibly. But its main task seems to be anti-shipping: firing missiles at enemy warships while denying their air defense cover."

Read the translated version of Karnozov's full article on the jump.
Chengdu J-20.
China's tool to ram "cheese boxes on rafts".
Vladimir Karnozov
(author's translation of the original text in Russian, published on 12 January by www.aex.ru)

On 11 January 2011 the new Chinese combat jet flew for the first time (in public, at least), taking off at 12:50 local time. The new airplane is referred to as the Chengdu J-20. Chengdu is the name of the city which houses a few aviation industry enterprises, including the aircraft manufacturing plant producing jetfighters and the design house developing them. A few outsiders watched the J-20 fly, as they happened "by chance" to be around the fence of Chengdu factory's aerodrome on that day. The flight itself was uneventful. It took place in the conditions of clear skies allowing photographers to make some good shots.

Before touching down, the pilot made several passes over the runway so as to expose his airplane to the cameras of "aviation admirers" all round the place. Those took photos of the aircraft from different angles and depicted everything they wanted except for doors of internal weapons bays.

These doors were either thoroughly hidden or removed from the shots by the picture takers on the insistence of very competitive advisers. But it is even more likely that these doors were not actually fitted to the J-20 first operable prototype. They are not needed on the very first operable aircraft dedicated to assessment of flight performance, flight envelope, various engine settings, functioning of the essential onboard systems, proving flight control algorithms. As a rule, third or even later prototypes are devoted to weapons testing, but these are yet to be constructed and outfitted.

The J-20 first public flight occurred just in time when US defense secretary Robert Gates was in Beijing on an official visit. Once there, he was trying to calm down the Chinese leaders who were much worried about pending deliveries of modern US-made weapons to Taiwan. Beijing considers this island an essential part of China.

A lot of pictures appeared on the Internet on the memorable day of 11 January. These shots gave more information on the new airplane. In particular, they reveal the shape of the wing and its positioning in relation to fuselage. This makes it possible to make some preliminary conclusions about the aerodynamics layout and technical characteristics of the J-20, and make guesses as to the main task the new jet shall be solving after entering squadron service.

The J-20 represents a relatively large tactical jet with the canards (foreplanes) and large delta wing. The fuselage length is somewhere between 22 and 24 meters, wingspan between 13 and 14 meters. By our estimation the maximum takeoff weight shall be in the region of 40 tons, and operating empty weight twice less than that.

Many aviation experts believe that the J-20 relies on a pair of Russian engines or their Chinese copies. In other words, the J-20's engines are picked out among members of the big family uniting the Item 117, AL-31F, WS-10G and WS-10 Taihang. Two engines together develop in between 30 and 40 tons of thrust. If that is so, then the capability of the propulsion system is enough for supercruise, or supersonic cruise flight at military power (highest power setting without afterburning). We may also expect that the J-20 with restricted fuel and combat load (for instance, when flying air-to-air mission) can fly vertical without losing speed at subsonic regimes and low altitudes.

The viewpoint that the AL-31F family engines power the J-20 is now prevailing. It could well be that J-20 operable prototypes have them in real life. If so, it is a good solution for initial testing, to rely on these well-tried and high-performance power plants. But in future the J-20 may appear with other types of engines. There were reports about China having got hold of the AMNTK Soyuz R-79/79M/179 series engines developed for the Yakovlev Yak-141 and other advanced fighter designs, - these were in development but cancelled for various reason. Ideally, the J-20 should have engines optimized for sustained supersonic flight, and the AL-31F is not such.

When in-flight photos appeared, the J-20 became the hottest topic for discussion among aviation enthusiasts round the world. But as it appeared, the enthusiasts, and even world-famous western journalists, had difficulty in classification of the new Chinese warplane. Is it a superiority fighter? Is it a supersonic bomber? Or, perhaps, it is a multirole, multimode airplane? Even columnists and experts with world's leading aviation magazines have hesitated to give their clear answer to these questions, - that in the view of them having good sources in the US and European intelligence bodies, defense ministries and the industry. It seems that not only journalists, but the professionals were in a state of shock after seeing the new Chinese bird.

First of all, let's determine J-20's center of gravity position. There are some photos available of the J-20 taxiing, in which we can clearly see its long fuselage, wing-to-fuselage connection and landing gears. The J-20 undercarriage is fighter's classics: three-point with a nose gear. And so it makes it easy to determine center of gravity position. To do that we take the main landing gear strut, and attach a line to it starting at the wheel's ground contact point. The line goes up with at an angle of, say, 15 degrees, leaning towards the nose of the airplane. The point where it crosses the fuselage center line is the most likely position for the airplane's center of gravity.

Here comes the first surprise: the likely center of gravity position rests... too far from the mean aerodynamics chord (MAC) of the wing. As a first iteration for aircraft designers, the center of gravity must be somewhere 25-35% of the wing's MAC, - like so is prescribed in the classic aircraft design books.

But the Chinese airplane appears to have the center of gravity position somewhere at MAC's edge. It is fairly strange for a maneuverable fighter, since balancing of the aerodynamic forces and the gravity will require relatively high deflection of the control surfaces - canards in the J-20's case. Should this airplane try to execute high-G maneuvers at subsonic speeds, the deflection of the canards could be a limitation. All this is rather strange for a maneuverable fighter... But not for the J-20, which does not appear to be one of those!

Let's take a look at other available photos, in which the J-20 goes in for landing with landing gear down. Apparently, the canards are set at a rather high positive angle (leading edge upwards), while the wing has its leading edge deflected downwards. The trailing edge surfaces are also deflected down, at rather a small angle. Obviously, at the approach for landing configuration, the wing's center line is highly curved by means of the leading and training edges down, which increases lift (achieved through altering the camber of the wing). But not so much as in the case of the classical flaps.

All this is, again, fighter classics for the delta winged aircraft with foreplanes. And here lies their limitation: the pilot cannot set the trailing edge further down, since the resulting lift force that builds up on the trailing edge will be hard to balance with the canards, in the view of their limited deflection scope (canards may stall at higher deflection angles).

It is well known from the aviation history how to enable delta-winged airplanes to generate more of the lift force at landing. For that purpose the canards are placed as close to the fuselage's nose as possible, to make a larger distance to the center of gravity. For instance, the Tupolev Tu-144 supersonic jet liner had foreplanes that were retracted into fuselage all the time except landing. But Chengdu designers did not do this. Rather, they positioned the canards fairly close to the center of gravity position, and thus sacrificed their effectiveness at landing for some other purposes.

What purposes? Firstly, for non-retractable foreplanes it is important to have them within the supersonic cone as it sets on the top of the airplane's nose at Mach numbers exceeding 1.0. This leads to a conclusion what the Chinese must have been purposely shaping the J-20 for supersonic flying.

Why did the Chinese shape the J-20 that way? Perhaps, they are unfamiliar with the classic solutions for a delta-winged, canard-equipped fighter? No, this is not the case knowing that Chengdu's previous design was the J-10 light weight fighter, now in PLAAF service. On its first public flight, the J-20 was escorted by a J-10B twin seater, the operational trainer version of the baseline J-10 single seat fighter. The J-10 was the star of the Airshow China 2008 and 2010, when it flew superbly with the PLAAF display team pilots at the controls. The J-10 is a very maneuverable airplane. This fact is the testimony of the Chinese designers' skills in development of maneuverable fighter aircraft.

The J-10 is a classic design with "proper" positioning of the center of gravity, like prescribed in the books. This is clear to tell looking at the main landing gear struts attached to the fuselage somewhere near 15-30% of the wing's MAC. So, let us ask ourselves the same question again: why did the Chinese designers shape the J-20 that way?

Here are some suggestions.
First, to achieve smooth airflow with desirable parameters at the entry to the engine's fan, the J-20's designers have to make the air intakes rather long - much longer than those on the F-22A Raptor or Sukhoi T-50 (PAK FA or FGFA). As it was put before, the J-20 prototype is likely to be flying on the AL-31s, but in future it may get a new engine type optimized for sustained supersonic cruise, - and that other engine is likely to be longer and require longer air channels. In any case, long air intakes were an important consideration at the design stage.

Second, the designers also needed to make air channels S-shaped, so as to hide the fan blades from the radio waves emitted by enemy radars. This is needed for a lower visibility of the airplane. It is worth to notice that the J-20's air intakes resemble those on the Lockheed Martin F-35 Lightning II ("diverterless" supersonic inlet, DSI). This gives move ground to assert that the J-20 is optimized for supersonic regimes and supercruise, much like the F-35.

Third, let us make distribution diagram for the airplane's cross section along the J-20's fuselage centerline. We need to take into account the thickness of the wing, canards and empennage. The diagram appears to be very smooth, - exceptionally smooth! It comes without a peak, running smoothly at approximately the same height from the tips of the air intakes all the way to the engine nozzles.

This seems to be the main thing about the J-20. Apparently, the Chengdu designers wanted to make the airplane's equivalent body of rotation as narrow as possible. And they needed to make provision for internal carriage of weapons, which is a characteristic feature of all fifth generation fighters. In actual fact, the J-20 appears to have much smoother cross section distribution diagram than the F-22A Raptor, the F-35 Lightning II and the Sukhoi T-50. Apparently, it required quite an effort from the Chengdu designers and so made them go for compromises on other things.

Should the Chendgu designers have made it "classic", they would not have moved the wing all the way towards the engine nozzles. But they did because it was the only effective way to make the airplane's body of rotation as narrow as possible, with the need for big air intakes, air-supply channels and internal weapons bays.

Again, this is the main thing about the J-20 design, and it sets it apart from all other known fifth-generation fighters. Other designs have "peaks" some 55-70% down the way from the fuselage nose tip to the engine nozzles (for the Su-27 family aircraft the respective figure is 55-60%, depending on version).

A smooth cross section distribution diagram is important for transonic drag. Supersonic aircraft are being designed in accordance with so-called "area ruling". For high Mach numbers (M>2) the distribution diagram is not that important as for the transonic regimes, M=1...1.5. It seems the Chinese designers optimized their new jet for transonic regimes and moderate supersonic speeds.

A huge effort on proper shaping of the Su-27 was made by Sukhoi designers in cooperation with TsAGI in order to improve its transonic performance. Three TsAGI's big wind tunnels, the T-112, T-108 and T-109 were used in the process. As a result of very accurate optimization of the fighter's cross section distribution diagram, the Su-27's "wave drag" was reduced by 25% - not before the designers virtually redeveloped the airplane (the initial aircraft was referred to the Su-27, the improved version became known as the Su-27S).

My impression from the J-20 is that it is an uncompromised airplane for supercruise, for flying at moderate supersonic speeds corresponding to Mach M=1.4-1.6. Such speeds can be achieved without afterburning. Surely, the J-20 can accelerate to M=2 and faster, but this would require engaging afterburners. In turn, the fuel burn will go high, lowering operational range of the aircraft and enlarging its heat signature.

In my view the Chinese designers optimized their new jet for M=1.4-1.6. Here comes the clue: the J-20 is a missile launching platform able to evade enemy interceptors by means of a high cruise speed. The J-20 may prove a good interceptor, - very possibly. But its main task seems to be anti-shipping: firing missiles at enemy warships while denying their air defense cover.

One day it may happen that the new Chinese jets would be used in anger. On such a day People's Liberation Army would order its pilots to attack enemy warships off the coast of a freedom-loving island not far from the mainland China. In that sense the J-20 is a likely replacement for the JH-7A strike aircraft.

The history of the powerful US Navy can be traced back to the famous duel of the USS Monitor and VSS Virginia (Merrimack) on 9 March 1862, the first-ever battle of ironclads. The USS Monitor, a 987-ton armored turret gunboat, was built at New York, with a large single cannon turret on a low freeboard. Although the Confederacy gunners scored hundreds of direct hits, shells bounced off her armor: the Monitor seemed to have impunity to enemy shellfire. After the battle, the North Americans constructed fifty monitors modeled on their namesake and made them the backbone of their navy. For their rather strange looks, these ships were called "cheese boxes on rafts". Since the memorable Battle of Hampton, the North Americans never lose at sea, and now their cheese boxes sail when and where they want. China prepares a tool to ram them.

回复 5# fix


    说到点子上了，四代机最给力的不仅仅是隐身，超音速机动才是空战的最终极绝招

回复 22# 冬天里
求签名图典故

回复 12# 波塞冬之戟

没那么长，只是长细比较大，看起来修长罢了。至于是不适合格斗，还得看气动布局和发动机。

回复 9# juelian1992


    现在中国的战机主要还是防御性质的，不像美国那样追求大航程，丝带主要是制空，没必要造的那么大和那么重，所以说丝带笨重是不对的。Ｆ２２不断的要求增加性能，导致越来越重，现在就是又粗哦又肥。丝带是苗条类型的。至于亚音速性能，只好不差。高速性能更是超出。

surfman 发表于 2011-2-27 11:18


    无力吐槽了

J20的使命就是在视距外,对目标发动致命攻击.
去狗斗不是主要作战方式

看热闹的还想当专家 呵呵

想要现在就分析出用途，也多为纸上谈兵。气动是实验来的，看出来的很少。。

好像现在美军演习中F22就是利用超音速下的机动能力在sm三代机吧？为什么J20就必须要把自己的速度放到三代机的水平来格斗呢？
另外图片可以分析重心了？X光眼看样子真的存在。

啥叫4S,啥叫超巡？亚音速机动是小意思，这就相当于刘翔和我比跨栏，那是随便虐的。

回复 8# 伯夷叔齐


    三代机的亚音速怎么缠住四代机的超音速？

   你飞四代机能让三代机把你缠住？

毛国的评论不看也罢，比得上山西陈醋。

馋嘴的野猫 发表于 2011-2-27 20:22


    黑丝那么大的身板不追求航程。。。。。。F-22已经嫌有些短腿了。

surfman 发表于 2011-2-27 11:18


    黑丝的设计的确是把超音速机动放在最重要的位置，还有大载荷大航程。隐身和过失速机动多少做了些妥协。
   但鸭翼和推力矢量可不是吃素的。
   四代机的超机动性意味着亚跨音速和超音速要全面压倒三代机，配合新一代格斗弹，不适合格斗这种神论就不要听了。。。。看看F-22的飞行表演吧。机动性往那里YY不会太离谱。

我觉得说的很有道理，从J20的体积看，更像是歼轰。毕竟对我国来说，对抗航母比F22更迫切。。。

黑丝控制面那么多 被说两句格斗不行   无以解释啊

狗斗恐怕只会发生在四代之间。四代之间的发现距离和三代对四代的发现距离是一样的（三代和四代配备预警机和雷达都可以使用一样的），这样一来双方四代之间一两轮超巡状态下中距弹对射之后，假如还在继续相对前进，就快要进入视距范围了。这时候才有狗斗可能。但是四代和三代之间应该很少存在狗斗的情形，四代一轮中距弹下来掉头超巡闪人，三代只知道自己被锁定要挨打了，连四代的位置都不知道，根本无法反击。

但是这样一来就有这么一种忧虑了，现在J20的图片出来之后普遍认为后向隐身欠缺，这意味着J20在面对F22的时候，对射一波中距弹后只能选择继续前进而不能选择掉头加力闪人，因为当对手的F22在面对J20的正向隐身时都已经可以锁定J20时，J20如果漏出菊花，F22的锁定距离将会更长。这样一来J20的空战战术选择会很少。当然了，J20还会有很多改进，而且她的假想敌更多的是压制F35。

综上，J20和F22两者一旦相遇，J20除了继续前进之外是没有其他选择余地的，而F22是全向隐身，与J20相遇后未必会选择继续前进进入狗斗，所以J20在设计上必须要有在狗斗中战翻F22的实力，才能逼对方露菊花跑路，如果J20没有这个实力，那么F22既可以选择一轮中距弹后闪人，也可以选择继续前进进入狗斗，这样J20就非常被动了。

狗斗恐怕只会发生在四代之间。四代之间的发现距离和三代对四代的发现距离是一样的（三代和四代配备预警机和雷达都可以使用一样的），这样一来双方四代之间一两轮超巡状态下中距弹对射之后，假如还在继续相对前进，就快要进入视距范围了。这时候才有狗斗可能。但是四代和三代之间应该很少存在狗斗的情形，四代一轮中距弹下来掉头超巡闪人，三代只知道自己被锁定要挨打了，连四代的位置都不知道，根本无法反击。

但是这样一来就有这么一种忧虑了，现在J20的图片出来之后普遍认为后向隐身欠缺，这意味着J20在面对F22的时候，对射一波中距弹后只能选择继续前进而不能选择掉头加力闪人，因为当对手的F22在面对J20的正向隐身时都已经可以锁定J20时，J20如果漏出菊花，F22的锁定距离将会更长。这样一来J20的空战战术选择会很少。当然了，J20还会有很多改进，而且她的假想敌更多的是压制F35。

综上，J20和F22两者一旦相遇，J20除了继续前进之外是没有其他选择余地的，而F22是全向隐身，与J20相遇后未必会选择继续前进进入狗斗，所以J20在设计上必须要有在狗斗中战翻F22的实力，才能逼对方露菊花跑路，如果J20没有这个实力，那么F22既可以选择一轮中距弹后闪人，也可以选择继续前进进入狗斗，这样J20就非常被动了。