J-20... The New Generation Fighter II

Also in mid-1960s the Sino-Soviet split also add to the fear of losing support, so self reliant became China's goal going forward. At this point engine might be one area, the catapult may be the other area where China is pushing hard to achieve some sort of break through.

Lion said:

I have some question. Suppose J-20 project started in the 90s or late 90s. Russian ask China for participation in their PAF-KA project but was rejected by the Chinese. I mean at that time, China is still not very advance in the aviation area and not to mention, modern aviation engine was even weaker.

What makes them so confident in thinking they can succeed this project alone? Usually, PLAAF top brass is quite conservative in their approach. Even participating in Russian project will not gain much in experience and knowleadge but at least China will stand to buy the 5th gen aircraft just like what the Indians are doing..

I don't mean J-20 is already a success but from the way it turn out now for the prototype, it seems like a bold decision to make when they reject the Russian offer that time.

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1967, the Sino-Soviet split, and China's first nuclear device.

15 years,as chinese commentator report, J-20 program started in the mid-90's

It's really cool picture, kept for desktop now...^^ But i still think if the author make the material color more like black is much more perfect~~~XD

Deino said:

For those who like the J-20 as a nice wallpaper !!

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Deino

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vesicles said:

You got to sever the cord sometime. It's better to become independent sooner than later. I don't think China has ever felt that depending on someone else on anything is the way to go. Even when China was backward, its goal has always been to become a leader... So buying weapon systems from another nation is simply a method to acquire the technology and to bridge the gap.

In the 90's, China already had some of the best 4th gen fighters in Su-27. I believe China was studying the design of 4th gen fighters carefully at the time and believed that, since China and Russia both only had 4th gen fighter at the time, the aviation technology gap between the two nations may be narrow enough for China to bridge by itself. At the time, China has been developing J-10 for quite a while and might feel good about their capabilities. And China felt that it might be in a position to develop the 5th gen fighter independently.

Plus, the terms of collaboration on PAK-KA might be too harsh for China to accept...

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You see, even if China were to participate in the research of PAK 50, there would be no guarrantee that PLAAF would be able to purchase the PAK 50 successfully. Even if China could buy, the 1990s era were the period China's economic couldn't enable it to sustain the aircraft as China economic was just growing then. Also joint venture doesn't give you the priority to be in the waiting list to buy, please correct me if I am wrong.

In Russian standard, the PAK 50 is classified as a 5th gen fighter in their own standard.

most important thing is money, if Rusia had plenty money, they don't want China participate the PAK 50 project, so, if China participated the project, that means the Russian took the Chinese money to develop their technology.
another word,we assume China's aviation technology in that time was backward to Russia, but China should use herself money to develop her own aviation technology, China may thus delay the fourth-generation fighters equipped, but in time, China will eventually has her entirely own technology.
paying money to the others only in exchange for the right to buy fighter,moreover, bilateral cooperation, there may be unpleasant, Russia may ask China for more money, but the aircraft development program may not successful, China has become the fool.

Learning from past experience and taking these experiences seriously is one thing that all nations would have to do. When China and Russia (Soviet Union) turned for the worst, Soviet Union had pulled back all her engineers and technical assistance from China, thus the Chinese were left alone to figure out many (at that time) high technology system herself.

This should already be a wake up call for China, and there is no one except one own self to depend on when it come to national interest and defence.

no_name said:

Brief summary from parts of the article:

All-moving tail fins were used to increase control surface area under supersonic conditions.

The vortex created at the front of the aircraft body will create a tendency for the tail section to swerve (like when you pull up the nose slightly and then roll)

This causes the plane tail section and tail rudder to experience a downward pressure, affecting adversely its vertical stability under high angle of attack. Making the nose of the plane hard to press downward. (in extreme cases it will do a flip and enter tail spin)

To solve this problem, the size of the tail is reduced from 20-25% to 10-13% (it didn't say with respect to what)

The tail is swept back due to consideration of the area rule, as the J-20 cannot extend it's horizontal stabilizers past the abrupt change in cross sectional area after the engine nozzle (like F-22 can) (since it uses canards instead)

F-22 and T-50 use slightly forward "butterfly tail", this is to reduce the blockage of tail surface by the aircraft body at high AoA. J-20 does not need to consider this because it had canards

hope this helps.

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Very often aircraft designers had to increase the size of the vertical tail plane area, especially in supersonic aircraft. Having to solve a problem by halving this area is spectacular. The tail planes indeed are very small. This means a significant reduction in weight and drag. I hope and trust they are not going to find that the tail plane area can be both too small and too large.

Ground-based radar can detect F-22/J-20 at 13.5 km, Rafale at 135 km, T-50 at 178 km

The EADS mobile ground-based "3D Radar System DR 174" can detect a F-22/J-20 at approximately 13.5 km, French Rafale at 135 km, and a Russian T-50 at 178 km.

The DR 174 only has 24 kilowatts of peak power and it operates in the L-band. Obviously, a permanent ground-based radar or AWACS will have more peak power, more radar bands (e.g. X-band, S-band, L-band, etc.), more powerful computers, better discriminating software, better-trained personnel, etc.

My calculations:

According to GlobalSecurity (see one of my earlier posts), the French Rafale has a RCS of 1 m2. We know that "the detection range [of the DR 174] against tactical aircrafts ("Swerling 1”- targets) with a radar cross section (RCS) of 1 m² is 135 km at a probability of detection of 90%."

We know that the "reflected power density at the radar receiver" is proportional to the fourth-root of the distance from the emitting radar or RCS (see ).

According to GlobalSecurity, the F-22 (and my estimate of J-20's front-profile) has a RCS of 0.0001. The F-22's/J-20's RCS is 10,000 times smaller than the French Rafale. The fourth-root of 10,000 is 10. Therefore, the detection range of the F-22/J-20 in comparison to the French Rafale is 13.5 km (e.g. 135 km/factor of 10 from much smaller RCS = 13.5 km).

Since the Russian T-50, with exposed engine compressor blades, has a RCS greater than the French Rafale's 1 m2, I have estimated the Russian T-50 RCS to be about 3 m2. The fourth-root of 3 is 1.316. Therefore, the detection range of the Russian T-50 in comparison to the French Rafale is 178 km (e.g. 135 km * factor of 1.316 from larger RCS = 178 km).

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3D Radar System DR 174


Bild 1: © EADS

The 3D radar system DR 174 is a highly mobile short/mid range surveillance radar operating in the L-Band. The radar system can be used as coastal radar for sea and air surveillance or as „gap fillers” for areas longer radars do not cover. The system can be integrated into existing defence networks, anti-aircraft (AA) weapon systems and other networks. It can also serve as a „stand alone” control center due the fully integrated state of the art working positions. A wide range of ECCM features and excellent clutter suppression ensure the detection of small targets even in a very hostile environment.

This 3D radar system operates in L-Band using a stacked beam active planar antenna. It features up to 8 elevation beams on receive. The system is designed in fully solid state technology.

The DR 174 Doppler radar features

* High unambiguous radial velocity due to appropriate pulse repetition frequency (PRF) stagger
* Frequency diversity
* High doppler resolution
* Detecting of tangential flying targets due to self learning ground clutter map

The detection range against tactical aircrafts („Swerling 1”- targets) with a radar cross section (RCS) of 1 m² is 135 km at a probability of detection of 90%. The detection range against tactical ballistic missiles with a radar cross section (RCS) of 0.1 m² is 75 km at the same conditions.

Waveform selection

The following statements highlight the capabilities of the DR 174 waveform selection:

* Different waveforms for various radar modes
* Non-linear frequency modulation
* Burst-to-Burst frequency change
* Burst-to-Burst pulse repetition frequency change
* Dual pulse for near range covering
* High range resolution waveforms

ECCM features

The electronic counter counter measures used by the DR 174 are:

* Frequency change from Burst-to-Burst
* Moving target detection processing with Doppler selective constant false alarm rate
* Low antenna sidelobes in azimuth and elevation
* Sidelobe blanking (SLB) (optional)
* Large receive dynamic range
* Selectable beam-processing
* Automatic jamming avoidance circuit (AJAC)

Clutter rejection

Excellent clutter suppression and detection of small targets in any type of clutter (ground- and rainclutter, seaclutter, chaff and angles) by:

* Very stable solid state transmitter
* Frequency agile synthesizer
* Moving target detection Doppler processing in frequency domain (sub clutter visibility)
* Ordered statistic constant false alarm rate in time domain
* High resolution clutter map
* Decreasing the size of resolution cell of radar (pulse compression with time sidelobes <45 dB)
* Matched detection threshold for each Doppler channel
* Tilting the antenna to higher elevation angles

ARM protection

Protecting against Anti Radar Missiles is supported by:

* LPT due to low transmitter peak power
* Transmitter silent sectors
* Very low antenna sidelobes
* Inherent system protection due to radar operating frequency band (L-Band)

The system consists of four major components the sensor (antenna group consisting of primary ans secondary radar), the Signal Processing (SiP) shelter, the Operations and Missions Control (OMC) shelter and the generator for reliable power supply in mobile deployment.

Also available is the DR 184, the long range version (400 km) of DR 174.


Figure 2: The concept of the DR 174 sensor

Re: Ground-based radar can detect F-22/J-20 at 13.5 km, Rafale at 135 km, T-50 at 178

Hmmm interesting .... are they saying the rafale has a lower RCS than the T-50?