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J-20 Design

The J-20 is a single-seat, twin-engine aircraft, bigger and heavier than the Sukhoi T-50 and the F-22. Comparison with ground-service vehicles points to an overall length of 75 ft. and a wingspan of 45 ft. or more, which would suggest a takeoff weight in the 75,000-80,000-lb. class with no external load. That in turn implies a generous internal fuel capacity. The overall length is close to that of the 1960s General Dynamics F-111, which carries 34,000 lb. of fuel.

The J-20 has a canard delta layout (like Chengdu's J-10) with two canted, all-moving vertical stabilizers (like the T-50) and smaller canted ventral fins. The stealth body shaping is similar to that of the F-22. The flat body sides are aligned with the canted tails, the wing-body junction is clean, and there is a sharp chine line around the forward fuselage. The cant angles are greater than they are on the Lockheed Martin F-35, and the frameless canopy is similar to that of the F-22.

Features at the rear of the aircraft-including underwing actuator fairings, axi-symmetrical engine exhausts and the ventral fins - appear less compatible with stealth, so the J-20 may not match the all-aspect stealth of the F-22. There are two possible explanations for this: Either the aircraft seen here is the first step toward an operational design, or China's requirements do not place as much stress on rear-aspect signatures. It is considerably larger than the US's most advanced air superiority fighter, implying long range, a generous internal fuel capacity and heavy weapons loads.

The impression is of a big, long aircraft, over 70 feet from nose to tail, which would make sense for a number of reasons. The J-20 may have lower supercruise performance and agility than an F-22, but with larger weapon bays and more fuel, according to Bill Sweetman, editor of Aviation Week/DTI. Chinese sources have claimed that production aircraft will be powered by two 13,200kg, WS-10 class high thrust turbofan engines, coupled with Thrust Vector Controlled (TVC) nozzles both made in China.

The J-20 nose and main undercarriage, and cheek weapon bay doors, all employ C-band through Ku-band optimised serrated edge design, similar to F-117A and F-22 design rules. The aft fuselage, tailbooms, fins/strakes and axi-symmetric nozzles are not compatible with good stealth performance, but these may be stop-gap measures to expedite prototype flight testing. The airframe configuration and aft fuselage shape would be compatible with an F-22A style 2D TVC nozzle design, or a non-TVC rectangular nozzle designed for controlled infrared emission patterns and radio-frequency stealth. Infrared signature would be influenced by other considerations, especially engine bypass ratio.

The choice of all moving slab stabilators and canards will impact RCS at deflection angles away from the neutral position. If large control deflections are produced in flight regimes other than close combat manoeuvring, the specular RCS of the all moving slab controls would need to be considered.

The canards - forewings close to the nose of the aircraft - provide maneuverability. The canard design utilizes the concept of two lifting surfaces, the canard functioning as a horizontal stabilizer located in front of the main wings. In effect, the canard is an airfoil similar to the horizontal surface on a conventional aft-tail design. The difference is that the canard actually creates lift and holds the nose up, as opposed to the aft-tail design which exerts downward force on the tail to prevent the nose from rotating downward.

The use of canards on maneuvering aircraft offers several attractive features, such as increased trimmed lift capability and the potential for reduced trimmed drag. In addition, the geometric characteristics of close-coupled canard configurations offer a potential for improved longitudinal progression of cross-sectional area which could result in reduced wave drag at low supersonic speeds. High instability requires sustained pitch authority at a high angle-of-attack, which in a conventional tail-plane would lose effectiveness due to stalling.

On the other hand, a canard can deflect opposite to the angle-of-attack, avoiding stall and thereby maintaining control. Canard is also known to provide good supersonic performance, excellent supersonic and transonic turn performance, and improved short-field landing performance compared to the conventional delta wing design. But they are also a good way to increase radar cross section and compromise the other stealth features. Unless the canards have to be on the same plane with the wings, they would significantly contribute to increase RCS regardless they are moving or not from 12 o'clock head on. And even if it's being aligned with the wings on the same plane and angles both horizontally and vertically, it would still contribute to increasing RCS nonetheless from a diagonal view.

Three pre-serial prototypes were flown: number ‘2012’ on 26 July 2014, number ‘2013’ on 29 November 2014 and finally number ‘2015’ on 19 December 2014. These displayed several differences from the first (and second) prototype aircraft, including new air intakes; completely redesigned nose section and radome (resembling the F-22/F-35); dielectric panels in the front fuselage below the completely redesigned canopy; EOTS (Electro-Optical Targeting System); differently shaped gear bays and slightly different tail fins tips.

On 13 September 2015 a new prototype, marked ‘2016’, began testing. This prototype was noticeably improvemed, including changed DSI bumps on the intakes, which suggests the possibility of new engines to power the fighter. This prototype may have more powerful engines, likely to be an advanced 14 ton thrust derivative of the Russian AL-31 or Chinese WS-10 turbofan engines. By 2020, the J-20 is planned to use the 18-19 ton thrust WS-15 engine, enabling the jet to super-cruise without using afterburners.

China's new J-20 stealth fighter jet bears similarities to an experimental prototype for a fifth-generation fighter jet produced by Russia's MiG aircraft corporation, the deputy editor of Russian military magazine "Arsenal of the Fatherland" Dmitry Drozdenko told Sputnik 02 November 2016. While the exact specifications of the aircraft remain under wraps, to all appearances the jets have been designed to match the stealth capabilities of fifth-generation fighter aircraft such as the Lockheed Martin F-22 Raptor and Russia's Sukhoi PAK FA.

Drozdenko told Sputnik that the J-20 he saw at the air show appeared similar to a Russian prototype fifth-generation jet fighter, the MiG 1.44, which was finally displayed last year. "In my opinion, the machine is based on the Russian MiG 1.44. That plane was created to compete with the PAK FA at the preliminary design stage, and made its maiden flight in 2000. The Chinese plane is very similar. Although it hasn't been announced officially, the J-20 uses our AL-31F engine, developed by Salut, which the Chinese bought for half a billion dollars," he revealed. Drozdenko is not the first analyst to note the similarity between the MiG 1.44 and the Chengdu J-20, photographs of which began circulating in 2010. Comparing the two fifth-generation prototypes, Defense Aviation spotted "startling similarities between the Chinese J-20 and the canceled Russian MiG-1.44."

TASS military observer Viktor Litovkin said "In China, they are able to copy the best models of military equipment, no doubt. They know how. But we must remember that a copy is always a little worse than the original," he emphasizes. “Comparison of the Chinese J-20 with the domestic MiG 1.44 is natural. The appearance of the two aircraft is very similar. As for the internal layout, questions arise. How accurately are the instruments and equipment copied?”.

While both have two engines, the J-20 has a wingspan of 12.9 meters, while the canceled Russian MiG-1.44 had a wingspan of 15 meters. Both have forward canards, but the J-20 engine inlets are on the side of the fuselage, while the MiG-1.44 inlets are on teh bottom of the fuselage. There are also major differences in the placement of the engines, and the rear empenage.

The capabilities of the fighter of the new generation Su-57 and J-20 in May 2018 compared the magazine The National Interest (NI). According to the publication, the Russian Su-57 is distinguished by greater maneuverability, even with the engine of the first stage, the AL-41F1. However, the efficiency of the aircraft will increase even more when installing a new engine. Also inferior to the J-20 and speed characteristics, but it is more secretive. The author explains this by the fact that when creating the J-20, technologies similar to those used in the development of American F-22 and F-35 were used.

In conclusion, NI wrote that the fifth generation Russian and Chinese fighters initially had different priorities. So, the J-20 is supposed to be used as a long-range strike aircraft, which would pose a threat to US bases and military facilities in the Pacific, as well as tanker aircraft and amphibious aircraft. Apparently, it is not planned to be used for air combat with US F-22 or F-35, except in cases of self-defense. "On the contrary, the Russian Su-57 is a machine for achieving superiority in the air, designed for hunting American fighters, such as the F-22 and F-35," the publication said.

The Chinese journal Shipborne Weapons reported in May 2019. pp. 36–41 that " While a gap remains in some respects between the J-20 and the F-22 and F-35, each has their pros and cons. For example, the J-20, due to the limitations of engine performance, maybe inferior to F-22 in terms of supersonic cruise capability and super maneuverability, but its significantly larger body size, giving it greater fuel capacity and endurance. It has a larger combat radius and mission set without needing to conduct aerial refueling. Based on photos released domestically, the J-20’s weapons bay has a width of 2 to 2.2 meters, a length of 4.5 to 4.7 meters, and a depth of 0.66 to 0.8 meters. At the same time, thanks to the rapid advancement of microelectronics and information technology since the 21st century, the capabilities of the airborne equipment, theater situational awareness and the collection, integration, and distribution of battlefield information are more advanced than those of the F-22 10 years ago, and similar to the more modern F-35.

"Compared with the F-35, whose internal weapons stores are small and which does not have supersonic cruise capability and super maneuverability, the J-20 has an internal weapons bay and a greater mobility advantage. So not only are there no generational differences with the F-22 and F-35, but the J-20 also has certain advantages. They have the ability to go out into the offshore airspace during the war and perform the tasks of competing with the foreign fourth-generation* aircraft such as F-22, F-35, etc. to compete for air superiority and to attack enemy air, sea and land targets."

Since the introduction of the J-20, the outside world is full of controversy about a design on it. This is the canard. There is a view that the J-20's canard affects the stealth of the aircraft and increases the frontal radar reflection area of the J-20, which is a vital performance indicator for the fifth generation. But in fact, Chinese media reported that according to the "Stars and Stripes" website report in September 2019 [no such report is otherwise in evidence], a US official specifically disclosed the data, adopted a three-dimensional modeling of the J-20, and analyzed the radar reflection area of this fighter in China, and the final data was 0.027 square meters. To be better than the F-35's 0.038 square meters, this shows that the J-20 has outstanding stealth performance.

China's J-20 fighter jet has been spotted equipped with pylon adapters under its wings, indicating the stealth aircraft may also be able to enter a "beast mode" like the US' F-35 fighter jet if needed by giving up some stealth capability in exchange for larger weapons loads. A J-20 prototype taking a test flight had two external pylon adapters, one under each side of its wings, and could carry a total of four extra missiles, Shanghai-based news website eastday.com reported on 01 June 2020, citing a recent photo widely circulated on Chinese social media. Judging by a performance flight at Airshow China 2018, a single J-20 can carry at least four PL-15 missiles in its main weapon bay and two PL-10 short-range combat missiles in its side weapon bays, when not using external adapters. This is similar to the US' F-35 fighter jet, which has a "stealth mode" that can only carry a small amount of internal ordnance and a "beast mode" that can carry a lot more internal and external ordnance.

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Page last modified: 28-10-2021 16:50:05 ZULU