Chengdu J-20 5th Generation Aircraft News & Discussions

[FairAndUnbiased]

This is a rough approach. EF2000's have been picked up and tracked and targeted in common NATO exercises, by planes, AWACS, and ground stations.
During such missions, the planes usually fly clean with instrumentation pods on and sometimes with training missiles, which the EF2000 carries in conformal slots in its belly.
The EF2000 is only marginally better than an F-16, and by marginally i mean it makes no real difference to the seeking radar.

I'm just establishing an upper bound. The EF-2000 has many non-optimal features such as single straight slab tail like Gambit said, instead of twin verticle canted slabs, lack of RAM paint and little consideration being made in wing and fuselage shaping, intake design, materials, etc.

What I'm saying is, the J-20 is not like a 15 m2 F-15 or Su-30. The upper bound of its RCS is the Eurofighter.

The lower bound for its RCS is probably the APA physical optics model.

I think it is more useful to establish lower and upper bounds for its RCS, rather than argue on how "truly" stealthy it is. No one will ever know.

 

[gambit]

For this image, you are looking at the F-117. So stop posting images to illustrate certain principles unless you can provide an explanation as to how these principles are applicable in many situations.

 

[j20blackdragon]

For this image, you are looking at the F-117. So stop posting images to illustrate certain principles unless you can provide an explanation as to how these principles are applicable in many situations.

So diffraction only applies to the F-117 and not to the PAK FA or any other aircraft? Please teach me more! I'm learning so much from you!

 

[j20blackdragon]

The only noticeable gaps on the T-50, that vary significantly with say the F22 are the gaps between the weapon bay doors.
These are of some concern, perhaps there is a reason or perhaps these are mock doors.

Gaps are just one of the problems on the PAK FA.

 

[Peaceful Civilian]

well mate apart from wasting time on doing worthless mathematical calculation ,instead u read the
advantage of passive detection capabilty of f22 raptor as it is the key of f22 survival in modern
conflict.
yes AWACS can be used for detection of F22 but the problem is by the time AWACS detected f22.
F22 would have earlier detected it thorugh it's passive detection capabilty & launched its AIM120d
BVraam missile towrads it .

Dude AWACS like ZDK-03 are very useful for detection. but there is still question who detect first.
But there are many alternatives.
Just need to Hack the F22 AN/APG-77 signals when F22 penetrate into enemy land., CIP(Common Integrated Processor) instructions of F22 can be alternated.When virus has penetrated into CIP THEN CIP instructions are alternated.Now we have control over F22 than the US airbase. Just see the advantage of this.
Even if CIP of f22 is alternated with malware. It can malfunction the F22.

 

[gambit]

Sources that I trust, told me that the APG-68 radar (V)9 cannot track the rear end of the F-22 at about 15 miles ...

Established systems like the AN-APG series can be improved with range increase and data processing power improvements, but against F-117 class targets, it is beamwidth tightening than range that can improve odds of detection. Beamwidth improvement or tightening can only be achieved with a new planar array and at some point, might as well drop the series and invest in AESA systems. According to my sources here in Nellis, with no enhancers, the beamshape loss effect, which is the combination of beamwidth and data processing, is exploited by the F-22's and F-35's backends to reduce their observability, which make the best position to detect both aircrafts from the aft sector is pretty much directly behind.

---------- Post added at 01:31 PM ---------- Previous post was at 01:30 PM ----------

So diffraction only applies to the F-117 and not to the PAK FA or any other aircraft? Please teach me more! I'm learning so much from you!

Man...So much for that supposedly 'high Chinese IQ'.

Kid, if you want to learn from me, use the 'Search' feature. Else keep quiet.

 

[marshall]

yes AWACS can be used for detection of F22 but the problem is by the time AWACS detected f22.
F22 would have earlier detected it thorugh it's passive detection capabilty & launched its AIM120d
BVraam missile towrads it .

The KJ2000 AWACS would be parked way beyond the range of the AIM120D. Besides, China is relying more and more on its UAVs and most likely has been developing datalinks to all of its air assets to improve its redundant real-time battlefield awareness.

 

[gambit]

I am saying that the Eurofighter RCS is an upper bound. It has a clean RCS of 1m2, and J-20 has internal weapons bays, so at the very most, it is an Eurofighter. It is likely to be better due to a few "superior" design features, but no worse. Do you agree in principle to this sort of assessment?

If you want to give the J-20 this latitude-cum-assessment, I have no problems with this speculation.

 

[SQ8]

... with no enhancers, the beamshape loss effect, which is the combination of beamwidth and data processing, is exploited by the F-22's and F-35's backends to reduce their observability.

Compared to the 22's fairly concealed nozzles.. arent the 35's a bit more exposed?

 

[gambit]

Compared to the 22's fairly concealed nozzles.. arent the 35's a bit more exposed?

Engine nozzles are NOT engine exhausts, even though it is easy to conflate the two. Engine exhaust is physically part of the engine. The nozzle is ancillary, meaning while it is crucial to support thrust operation and shaping, it can be discarded for another nozzle design and/or shape without you discarding the engine. So it is the exhaust that is sort of 'concealed' and it is the nozzle that is exposed.

You can try these...

http://www.defence.pk/forums/china-...craft-updates-discussions-71.html#post2392632
http://www.defence.pk/forums/military-forum/20908-rcs-different-fighters-8.html#post2111258

For both of the above, both nozzle designs incorporated the famous 'saw-tooth' pattern to disperse diffracted signals in directions other than back to source direction. The F-22's nozzles just happened to have the largest of that pattern.

 

[SQ8]

Engine nozzles are NOT engine exhausts, even though it is easy to conflate the two. Engine exhaust is physically part of the engine. The nozzle is ancillary, meaning while it is crucial to support thrust operation and shaping, it can be discarded for another nozzle design and/or shape without you discarding the engine. So it is the exhaust that is sort of 'concealed' and it is the nozzle that is exposed.

You can try these...

http://www.defence.pk/forums/china-...craft-updates-discussions-71.html#post2392632
http://www.defence.pk/forums/military-forum/20908-rcs-different-fighters-8.html#post2111258

For both of the above, both nozzle designs incorporated the famous 'saw-tooth' pattern to disperse diffracted signals in directions other than back to source direction. The F-22's nozzles just happened to have the largest of that pattern.

Ok..
What I intended to actually point out what that the F-22's clamshell nozzles fit clean between the two "protrusions" if you will of the tailplane.

Compared to that.. the F-35's nozzle(taking the picture in your redirects as ref) have a large space between them and the tailplane.
a)How does that possibly contribute to the RCS when either viewed from an angle or from below?
b)what possible phenomenon/engineering reduces that return(not counting the saw tooth petals)?

 

[gambit]

Ok..
What I intended to actually point out what that the F-22's clamshell nozzles fit clean between the two "protrusions" if you will of the tailplane.

Compared to that.. the F-35's nozzle(taking the picture in your redirects as ref) have a large space between them and the tailplane.
a)How does that possibly contribute to the RCS when either viewed from an angle or from below?
b)what possible phenomenon/engineering reduces that return(not counting the saw tooth petals)?

You are correct there. The F-35's engine/nozzle configuration is necessary that way because of its multi-role multi-service requirements. But for the F-35, the gaps between the nozzle and tailplane assembly may not be as significant an RCS contributor as feared. That does not mean the F-35's backend is as low observability as the F-22's. At least not in my opinion any way. But what it mean, in my opinion, is that under certain scan/view angle, the F-35's nozzle may have a greater EM 'flare' or 'glint' than the F-22's.

Let me put in this analogy...

Say you are looking at a line of soldiers. At the extreme ends, your target view would be minimal, you would not know if there are any gaps between individual soldiers. In fact, you may see only one soldier. But as you move or increase your scan/view angle to approach perpendicular, you will begin to see more soldiers and those gaps between them.

This is how radar often perceive complex bodies: That instead of a gradual rise in reflected signals, certain structures on said body will create a spike, and the system will flag that spike in memory for other purposes.

I do not think that the F-22's and F-35's nozzles are comparable in RCS contributorship with the F-35's the greater. But I believe that difference is significant to only within a very narrow range of scan angles from any direction. We may never know the degree of that difference and at which scan angle will that difference manifest itself.

 

[houshanghai]

J20 made its first flight on this day last year 2011.1.11

 

[teddy]

New J20 video

 

[DrSomnath999]

The KJ2000 AWACS would be parked way beyond the range of the AIM120D. Besides, China is relying more and more on its UAVs and most likely has been developing datalinks to all of its air assets to improve its redundant real-time battlefield awareness.

no man u r completely wrong on this F22 is not 4or4.5 gen fighter that it would detect it from
miles away

i quote from an article

According to the information I know, the modern AWACSs today like E-2C Hawkeye 2000 and
E-3C are capable to the detect the target of RCS = 1m2 class 250~300 km away.

And their maximal effective detection range to the fighters in the world should be:
F-15C & Su-27 (RCS = 10~15m2): 450 ~ 600 km
Tornado (RCS = 8 m2): 420 ~ 500 km
MIG-29 (RCS = 5 m2): 370 ~ 450 km
F/A-18C (RCS = 3 m2): 330 ~ 395 km
F-16C (RCS = 1.2 m2): 260 ~ 310 km
JAS39 (RCS = 0.5 m2): 210 ~ 250 km
Su-47 (RCS = 0.3 m2): 185 ~ 220 km
Rafale (RCS = 0.1~0.2 m2): 140 ~ 200 km
F-18E (RCS = 0.1 m2): 140 ~ 170 km
MIG-42 (RCS = 0.1 m2): 140 ~ 170 km
EF2K (RCS = 0.05~0.1 m2): 120 ~ 170 km
F-35A (RCS = 0.0015 m2): 50 ~ 60 km
F/A-22 (RCS < or = 0.0002~0.0005 m2): < or = 30 ~ 45 km
http://www.f-16.net/f-16_forum_viewtopic-t-3018-start-30.html

but F22 can detect it from 150 -200 miles thanks to it's ALR 94 passive detection ability

& regarding range of aim 120 d i quote

AIM-120D
Formerly known as AIM-120C-8, the AIM-120D has a two-way data link, more accurate navigation using a GPS-enhanced IMU, an expanded no-escape envelope, improved HOBS (High-Angle Off-Boresight) capability, and a 50% increase in range, bring it to the 180 km class. The AIM-120D is a joint US Air Force/US Navy project.
Raytheon (Hughes) AIM-120 AMRAAM - Scramble

so F22 can easily lock & fire aim120D thanks to the help OF ALR 94 system


And UAVs can detect F22 i doubt if u can prove it i would be enlightened