The Chinese J-20

The Chinese Peoples Liberation Army Air Force (PLAAF) burst onto the stealth fighter scene in January 2011 with the unveiling of the J-20 Stealth Fighter.  The first flight of this enigmatic aircraft occurred during a visit by U.S. Defense Secretary Robert Gates to the Chinese mainland, which visit was intended to diffuse military tensions between the U.S. and China.

Since the J-20’s maiden voyage the Internet has virtually exploded with pictures and video of the aircraft, but a great many questions about the world’s latest stealth fighter remain unanswered.  I want to provide you with a quick update as to where the jet is in terms of development and what issues analysts believe the fledgling aircraft faces.

As we know, the PLAAF has gone to great lengths to look good in the eyes of the world.  They tried to make us think their J-10 fighter was doing some good work by showing us a video of the J-10 shooting down another aircraft that looked eerily similar to one of the “MiGs” in the movie Top Gun. (Read the story and see the video here)

So is the J-20 an attempt to look relevant in reaction to Russia’s unveiling of the PAK-FA, or is it a viable attempt at kicking off a fleet of 5th generation fighters?  Doctors Michael J. Pelosi and Carlo Kopp conducted research on the specular radar cross-section of the J-20.  Pelosi and Kopp ran a physical optics simulator algorithm that tested the design (shaping) and known Chinese low observable coatings of the J-20.  They did a similar analysis of the Russian PAK-FA and found the J-20 to have superior stealth characteristics.

So it seems the J-20 is a viable stealth platform…at least in the forward hemisphere.  The researchers noted that based on the engine exhaust nozzle design the aircraft’s RCS is significantly increased in the aft hemisphere – which leads us to the next question: are the current engines a stop gap measure until better stealth engines are developed?  Or will they be permanent fixtures on the J-20?

The two airworthy prototypes of the J-20 each have different engines.  The first prototype (dubbed #2001) has Russian built engines originally designed for the Su-27 (Salyut AL31FN turbofan engine) and currently in service in the Chinese J-10.  The second prototype (#2002) has essentially the same engine as reverse engineered and built by the Chinese.  Neither has thrust vectoring capability, which leads analysts to believe the engines will eventually be replaced.  Regardless, the J-20 is meant to supercruise (fly above the speed of sound without the use of afterburner) and will need engines capable of supporting that intent.

http://vitalykuzmin.net/?q=node/292

Ok, so it’s low observable and it’s fast (possibly getting faster), what about its sensors, avionics, and weapons?  Much is unknown in these areas.  A look at the cockpit of an early J-20 simulator mock-up seems to indicate the presence of integrated avionics – computers that process and fuse data from different sensor sources to provide the pilot with a federated display of the combat airspace.

www.chinesedefense.com

With respect to the weapons, the Chinese may have improved on the side weapon bay door concept of the F-22.  Testing is underway and photos have shown how the side weapon bays operate allowing the missile to be extended with the doors closed.  This will reduce the drag associated with employing air-to-air missiles from those bays while allowing the missile seeker to remain relatively unobstructed for target acquisition.  It is my opinion based on the photos I’ve seen of the extended missile that any missile seeker hung from the side weapon bays will experience significant fuselage blanking due to the fact that the missile is situated directly against the body of the aircraft instead of being further extended into the slipstream.

Finally, let’s take a step back and look at the overall design.  It is very clear the Chinese learned a thing or two by watching the F-22.  Several design features seem to copy almost precisely the shape of the F-22 (just take a look at the canopies!)

businessinsider.com

The most striking difference between the J-20 and the F-22 is the size.  The J-20 will be able to carry more internal fuel allowing it a larger combat radius.  It could also potentially be able to support a great weapons load out.  I’m not going to speculate on maneuverability of the aircraft like several so-called analysts have.  Until I see an Energy-Maneuverability (EM) diagram, it’s really impossible to tell how it will match up against a Raptor.

In summary, I think the J-20 may eventually be a viable competitor to the F-22.  In time we will learn what type of sensors and weapons the aircraft will employ and we may eventually see upgraded engines by the time the fighter is operational (somewhere between 2017 and 2019).  Until then, the Raptor will continue to rule the skies!

** Quick note: It appears the Chinese are fielding an additional stealth fighter, which will smaller and look much more like the F-22.  It is being called the J-31 – we’ll bring you more on this latest development soon!

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