Improved Chinese Stealth Fighter Nears First Flight

[xhw1986]

The latest example of the stealthy Chengdu J-20 fighter has recently undergone high-speed taxi testing at the company airfield, suggesting that a first flight is imminent, possibly scheduled for this weekend. Thought to be the third flying example of the J-20, the new aircraft is being considered as a true developmental airframe for an operational fighter, and has introduced a number of significant improvements over the two technology demonstrators that preceded it. Many of the changes are measures taken to reduce the type’s radar cross section.

With the side number 2011, the new J-20 introduces sawtooth trailing edges on the two engine nozzles. It also has the aft tips of its all-moving vertical fins cropped, a feature that has been applied to at least one of the earlier aircraft. Aircraft 2011 additionally has the tips of the canard foreplanes cropped. The engine intakes have been redesigned with a sloping upper edge and larger capture area, while the underwing fairings for the control-surface actuators have been reprofiled and reduced in size. The main weapon bay doors have been redesigned with a more sophisticated sawtooth pattern on leading and trailing edges, while the nosewheel door pattern has been simplified. Most noticeable, however, is a new paint scheme with what appears to be a special coating applied to the edges of the wings and tail surfaces.

Another notable change is the addition of a low-profile fairing under the nose for an electro-optical/infrared sensor, which may provide an air-to-ground function as well as air-to-air tracking capability. Prototype 2002, the first with radar, appeared earlier with a pedestal for an infrared search-and-track system forward of the windshield, but aircraft 2011 has an undernose installation redolent of the EOTS (electro-optical targeting system) fitted to the Lockheed Martin F-35. The J-20’s radome, with canted bulkhead, almost certainly houses an AESA radar. One further change for aircraft 2011 is the addition of a solid arch frame to the one-piece canopy.

Meanwhile, the first two J-20s (2001 and 2002) have been active at the CTFE (China flight-test establishment) at Yanliang, to which they were transferred from Chengdu in 2012. Google Earth imagery from Yanliang has provided a good size comparison with the slightly larger Sukhoi Flanker. Sightings of a “2003” and “2004” have thrown some confusion on the exact number of J-20s, but it is likely that the first two machines have either been renumbered or photos have been faked.

Aircraft 2002 was used to perform initial tests with the J-20’s innovative missile launch system for the side bays, in which the bay doors close after the PL-10 missile has been swung out into the airstream before firing. This is an advance on the F-22’s side bay system, in which the bay doors remain open throughout the whole deployment/firing sequence, with a consequent penalty in radar cross section. Another aircraft, almost certainly 2001, has recently appeared in a silvery scheme with a dark radome, and with its fin tips cropped like those on 2011. This aircraft may have been conducting tests with a radar-absorbent material.

Improved Chinese Stealth Fighter Nears First Flight | Aviation International News

 

[Umair Nawaz]

can anybody tell me abt chinese stealth bomber?

china had produced a stealth bomber like B2 spirit in 2009.

 

[xhw1986]

china had produced a stealth bomber like B2 spirit in 2009.

Really ?

 

[Umair Nawaz]

Really ?

yes first 3 pictures.

chinese stealth bomber - Google Search

 

[xhw1986]

Modified J-20 seen being prepared for maiden test flight

Images emerged on 20 February of a modified prototype Chengdu Aircraft Corporation (CAC) J-20 fifth-generation fighter undertaking high-speed taxi runs.

These taxi runs are presumably prior to its maiden flight and suggest it may be a pre-production variant slated for formal testing by the People's Liberation Army Air Force (PLAAF).

Photographs of the prototype first appeared on Chinese military web sites in December 2013 and January, although some of these images appeared to have been digitally altered. The prototype carries the bort number '2011' and shows modifications intended to improve engine performance, combat capability and stealth.

Most noticeable are redesigned engine intakes featuring more of a sloped 'caret' design said to improve pressure distributions for the engine. The vertical stabilizers have been clipped in their outer aft corners and the main wheel doors and the internal weapons bay cover feature larger scalloping to aid low observability. The canopy also features a new brace.

A new electronic targeting system is located below the nose and just aft the radar. This and the J-20's distributed infrared sensor system points indicate Chengdu's ambitions to give the J-20 an optical and infrared targeting and warning system similar to that of the Lockheed Martin F-35 Joint Strike Fighter.

The new intake shape and electronic targeting system may also suggest multirole ambitions for the J-20, which has a larger internal weapons bay than the F-35.

On 16 February China's Securities Times Online reported that a demonstrator version of the 15-ton thrust WS-15 turbofan, the J-20's expected engine, may be completed in 2014. Other sources note the WS-15 may not be ready for service entry until 2020 and indicate that continued difficulties in its development will lead to the adoption of Russian engines for initial J-20 production.

If this is the case then the J-20 may be first powered by a version of the 13.5-ton thrust Saturn AL-31F-M1, with the 14.3-ton thrust AL-31-M2 or the 14.5-ton thrust Saturn 117S possible later options. In 2010 reports suggested that China was seeking the 117S turbofan for the J-20 but so far Russia has been reluctant to sell China this engine separately from the Sukhoi Su-35 fighter.

Fitted with Russian engines initial production aircraft could emerge as early as 2015 for testing by the PLAAF, with service entry following in 2017 and initial operating capability (IOC) by 2019.

Other sources have suggested that a tandem twin-seat 'J-20S' may also emerge in 2014, raising the possibility of an eventual dedicated fifth-generation strike fighter that could rival the Shenyang Aircraft Corporation's twin-seat fourth-generation J-16 attacker, now in testing.

COMMENT
Design refinements are an expected result of early aircraft prototype development although it is unclear whether these modifications represent the definitive pre-production standard for the J-20.

If the reported production time-line holds, then CAC is on schedule to fulfill PLAAF General He Weirong's 9 November 2009 prediction that China's fourth-generation (fifth-generation in Western terminlogy) fighter could enter service in "8 to 10 years."

Modified J-20 seen being prepared for maiden test flight - IHS Jane's 360

 

[Kompromat]

solid arch frame to the one-piece canopy.

@gambit | does this offer benefits over a single piece canopy? - Doesn't the metal frame inside increase the radar signature?

 

[Hamartia Antidote]

@gambit | does this offer benefits over a single piece canopy? - Doesn't the metal frame inside increase the radar signature?

I think they are used in Naval craft due to birdstrikes.

 

[Akasa]

@gambit | does this offer benefits over a single piece canopy? - Doesn't the metal frame inside increase the radar signature?

The RCS would almost be largely unaffected due to the RAM coating on the glass which prevents energy from escaping from or entering the cockpit area, as seen on the J-15, J-10B, and J-16. It helps with ejection.

I think they are used in Naval craft due to birdstrikes.

This would be an inaccurate assumption; the brace is there to strengthen the glass and also support line charges.

 

[cirr]

Maiden flight on going。。。。。。

Landed after 24 mins flight！

 

[cirr]

J-2011 first flight escorted by a J-10S

 

[HariPrasad]

Congrats!!!!!!!

 

[Dr. Strangelove]

 

[cirr]

 

[Beidou2020]

 

[gambit]

@gambit | does this offer benefits over a single piece canopy? - Doesn't the metal frame inside increase the radar signature?

Only if radar signals are allowed pass-through as mentioned by our Chinese member. The coating is essentially electrical conducting so the issue boils down to composition and method of deposition of the mixture. Gold gives that unique tint. Chemical vapor deposition (CVD) method that are common in semicon products manufacturing processes is the method and it is tricky. The method deposit can be as fine as an atomic layer at a time.

===>>> Chemical vapor deposition <<<===

Since the goal is to reduce the cockpit well's contributorship to total RCS, it is easy to think that coating the canopy will solve that problem. It does not. Once the canopy is coated with an electrical conductor, the canopy itself is now the dominant contributor in lieu of the cockpit well. The canopy, not the cockpit well, is now the problem. May be not as great, but a problem nonetheless.

Here is the difference...

The cockpit well is concave (top) and an amplifier, usually directional and towards the source direction. The canopy is convex (bottom) and will radiate in all direction. Diffused? Yes, but radiate nonetheless and if the right combination of freq and power exists, it will raise the cockpit area over a threshold and possibly revealing the aircraft. So it is not something as simple as tossing the canopy into the oven, vacuum the oven, and start pumping gas into the oven.

The canopy must be as precisely designed with the goal of redirecting impinging radar signals as any structure on the aircraft. Since the canopy itself is a structure with the highest gradient of curvatures than any other structure, surface waves will be induced as well as allowing pass-through into the cockpit well.

And if there are surface waves, what is the danger...???

It is surface discontinuities.

In other words, the canopy glass itself must be of the highest quality possible, as free of microscopic imperfections as possible. After all, what is the point of RCS control -- if the canopy contains microscopic surface pits, valleys, and trenches and now an electrical conducting coating is making surface waves easier to travels into those microscopic concave structures? So the result is: While the coated canopy prevents pass-through into the cockpit well, the canopy glass itself contains enough microscopic pits, valleys, and trenches to radiate, assisted by an electrical conducting coating material, into free space and in all direction.