Anti-Stealth Sensors to Tackle Chinese and Russian LO Designs (detection of J-20 and PakFa)

With first flight out of the way, the discussion about China’s new J-20 stealth prototype is switching to the aircraft’s mission (fighter or, more likely, long-range strike), sensors (strike missions would require a high-resolution long-range radar) and communications (which would demand high-speed datalinks and sophisticated integration).

The Chengdu J-20 design has struck most analysts and observers as familiar and somewhat different that the Lockheed-Martin F-22 and F-35 as well as the Sukhoi T-50.

“The J-20 is reminiscent of the Russian MiG 1.42 both in terms of planform, and also with regard to the rear fuselage configuration,” says Douglas Barrie, senior fellow for military aerospace at London’s International Institute for Strategic Studies. “The most obvious difference is the greater forward fuselage shaping as the basis for low observable characteristics, along with the different engine intake configuration. The MiG program was cancelled by the Russian government around 1997.”

Another issue that will continue to surround all stealth designs is how long will current stealth designs offer invulnerability as air defenses adopt even larger and more powerful AESA radars. From the early days of AESA development, a key goal was to build a radar that can detect a very small object like a cruise missile at a distance great enough to target and shoot it down or a larger object like a fighter with a very low observable treatment.

Airborne detection of stealth aircraft may have already been accomplished in a series of tests done at Edwards AFB, Calif. in the second half of 2009. Those with insight into the research say Lockheed Martin’s CATbird avionics testbed –a 737 that carries the F-35 joint strike fighter’s entire avionics system -- engaged a mixed force of F-22s and F-15s and was able to target the F-22s.

"The F-35 mission systems suite is the most sophisticated and powerful avionics package of any fighter in the world," said Dan Crowley, Lockheed Martin executive vice president and F-35 program general manager at the time of the tests.

His clue about the fighter’s anti-stealth capability is in a reference to confronting new, sophisticated, foreign aircraft.

“The F-35's avionics include on-board sensors that will enable pilots to strike fixed or moving ground targets in high-threat environments, day or night, in any weather, while simultaneously targeting and eliminating advanced airborne threats,” Crowley said.

An interesting comment on the site:

No doubt J-20 is a very good news to Sukhoi since its appearance further insures proper funding of the PAK-FA/FGFA joint 5gen program by both Russian and Indian governments.

The same can be said about the F-22 Raptor. The J-20 is the best news that could come out when it comes to development funding for the Raptor (e.g. side arrays that were originally designed but not yet funded, updates from the F-35 sensor suite, etc), as well as the possibility for additional Raptors (maybe the next administration, but even in this one it does appear that Gates was somewhat shaken). Thus this may very well be good news.

The tests of the jumbo jet with F-35 avionics being able to detect Raptors is quite interesting, particularly for LO platforms that offer even greater RCS signatures than the Raptor (which is basically every manned platform out there).

And once the Chinese steal the design of the Raptor-detecting avionics, the Raptor becomes just another fighter. A very expensive one.

If the Raptor can be observed and engaged at missile range, then the winner will be whoever brings the most aircraft to the fight.

It means 'Low Observable,' i.e. stealthy at some level. A plane like the Raptor is VLO, or very low observable, indicating a higher degree of measures taken to reduce its RCS (radar cross section, with a smaller RCS being better from a detectability point of view than a larger RCS). For example, some sources have the F-15 having an RCS of 20^m2, while that of the Raptor is allegedly 0.0001m^2. To get VLO means a lot of things, ranging from shaping (better shaping equals a lower RCS) to RAM (radar absorpment materials and coating) to internal carriage of weapons (fewer reflective targets) to measures to reduce infra-red detection. They also have RADARs that have LPI (low probability of intercept) and low side-lobes, meaning that the enemy will find it harder to detect the stealthy fighter detecting him. This does not make a plane invisible (it can still be detected by RADAR), but what it does is make it less visible, less identifiable against clutter, and more importantly, reduce the distance at which an enemy RADAR would be able to detect it (e.g. imagine a RADAR can detect and form a good tract against the Raptor at 20 miles, but the Raptor's weapons can take out that target at 80 miles ...advantage Raptor). Even with this a lot of stealthy planes still use jamming escorts (eg. Prowlers and Growlers), which makes it even more difficult for the enemy to detect, and track, the stealthy target (at least until it is operationally too late). Thus, stealth is not a magic bullet, but it makes it soooooo difficult for the enemy that it provides substantial advantages for the stealthy platform.

By the way, almost all of us are rookies here. There are a couple of FReepers who have real operational knowledge (like one chap who was an actual Raptor pilot in another military forum and got himself in a spot of trouble when he, allegedly, said too much), but the vast majority of FReepers (such as myselfs) are simply rookies with an interest in aerospace. Thus no rookie questions. What I have posted above is my best understanding of LO/VLO put in a straight forward manner. There is supposed to be something called XLO (Extremely Low Observable), but that will be for future unmanned systems.

Anyways, that is stealth for you. Extremely helpful. While it is not invincible nor invisible, and it still requires a good level of support, it provides that crucial edge necessary to make the other chap die for his country.

I hope that helps.

Oh, I wouldn't call the 737-based CATBird a jumbo jet. However, the F-22 has an even larger and more powerful AESA radar than the F-35, thanks to the F-22's larger nose housing a larger antenna array. It should be able to detect a J-20 fairly easily. However, it is our existing AWACS aircraft I worry about.

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