Chengdu J-20 5th Generation Aircraft News & Discussions

[ptldM3]

WZ-10 is a stealthy helicopter. It is stealthy because it has low RCS features not found in most other combat helicopters like an Mi-24.

J-20 is a true 5th generation VLO fighter with RCS comparable to F-22. T-50's RCS is 0.5m2 so it is not a true 5th generation VLO fighter. It is an LO fighter like Silent Eagle (which also has internal bay), so basically it's a Silent Flanker.

The WZ-10 is just about as stealthy as a dump truck full of manure. I was not aware that fix landing gears, vertical stabs, large gun, pylons, and a FLIR were stealthy. I still find it funny that Chinese members here jump up and down pointing fingers at something as small as an IRST on the pak-fa and than shrug off the fact the WZ-10 has more junk hanging off of it than a Christmas tree.

And for your information the Silent Eagle has the same frontal RCS as the F-35.

 

[Tracy]

Hey My 1st Post
Canards have poor stealth characteristics....but is there anything like stealthy canards ?

 

[Wet Shirt Contest]

Hey My 1st Post
Canards have poor stealth characteristics....but is there anything like stealthy canards ?

Hello Tracy And Welcome

YES Canards can be stealthy but stealthy canards are usally very difficult to shape and harmonize with performance, the J-20 has planform alignment in the canards trailing and leading edges but its planforming is not as good as on other designs, its canards have leading edges aligned with the wing leading edges and their trailing edges aligned with the wing trailing edges, however the wing`s LERX is not aligned with the wing or canard so the LERX leading edge is not aligned with the wing or canard leading edges or trailing edges, this will affect its stealth and reduce its effectiveness....

The Dihedral of the canard is not aligned as the dorsal V tail with the flat sides of the fuselage and the forebody flat sides in fact is not aligned with anything, this is only an aerodynamic need, this also will reduce its stealth effectiveness.
So its planform alignment is not PERFECT.....

 

[Zabaniyah]

WZ-10 is a stealthy helicopter. It is stealthy because it has low RCS features not found on most other combat helicopters like an Mi-24.

J-20 is a true 5th generation VLO fighter with RCS comparable to F-22. T-50's RCS is 0.5m2 so it is not a true 5th generation VLO fighter. It is an LO fighter like Silent Eagle (which also has internal bay), so basically it's a Silent Flanker.

I stopped reading after that. I really did.

 

[Martian2]

World stealth fighter rankings (updated citations)

#1 F-22 Raptor - RCS is 0.0001 m2 (from GlobalSecurity citation)

#2 J-20 Mighty Dragon - RCS is intermediate between F-22 and F-35 (Frontal and side-aspect RCS is 0.0001 m2 like F-22. Rear-aspect RCS with round LOAN engine nozzles is 0.005 m2 like F-35. See Australia Air Power citation below.)

#3 F-35 Joint Strike Fighter - RCS is 0.005 m2 (from GlobalSecurity citation)

#4 T-50/Pak-Fa - RCS is 0.5 m2 (from Russian Embassy in India official website citation)

References:

GlobalSecurity: Radar Cross Section (RCS)

Russian Embassy in India official website: India, Russia close to pact on next generation fighter

----------

Australia Air Power: J-20 is a "genuine Very Low Observable design"

J-20 Mighty Dragon is a "genuine Very Low Observable design" except for round engine nozzles, which can be fixed.

The Chengdu J-20: Peace in Our Time?

"This study has therefore established through Physical Optics simulation across nine radio-frequency bands, that no fundamental obstacles exist in the shaping design of the J-20 prototype precluding its development into a genuine Very Low Observable design.

Above: L-band RCS, below X-band RCS head on, both in PCSR format (M.J. Pelosi).

Engineers and Scientists who work in ‘stealth’ (AKA ‘Low Observable&#8217 designs have a way for explaining it to lay people: ‘Stealth’ is achieved by Shaping, Shaping, Shaping and Materials (Denys Overholser).

The F-22A is clearly well shaped for low observability above about 500 MHz, and from all important aspects. The J-20 has observed the ‘Shaping, Shaping, Shaping’ imperative, except for the axisymmetric nozzles, and some curvature of the sides that smears a strong, but very narrow specular return into something of a more observable fan. The X-35 mostly observed the ‘Shaping, Shaping, Shaping’ rule, but since then, to quote a colleague, ‘hideous lumps, bumps, humps and warts’ have appeared on the JSF to disrupt the shaping imperative, forcing excessive reliance on materials, which are at the rear-end of the path to ‘Low Observability’.

While discussing ‘rear-ends’, both the F-35 and the J-20 have large signature contributions from their jet nozzles. However, the difference is much like the proverbial ‘Ham Omelette’: the F-35 Pig is committed, but the J-20 Chicken is a participant. If the Chinese decide that rear sector Low Observability is tactically and strategically important, they are at the design stage where they can copy the F-22A nozzle design for the production configuration of the J-20."

[Note: Thank you to HouShanghai and 蓝胖 for the picture.]

 

[DARKY]

World stealth fighter rankings (updated citations)

#1 F-22 Raptor - RCS is 0.0001 m2 (from GlobalSecurity citation)

#2 J-20 Mighty Dragon - RCS is intermediate between F-22 and F-35 (Frontal and side-aspect RCS is 0.0001 m2 like F-22. Rear-aspect RCS with round LOAN engine nozzles is 0.005 m2 like F-35. See Australia Air Power citation below.)

#3 F-35 Joint Strike Fighter - RCS is 0.005 m2 (from GlobalSecurity citation)

#4 T-50/Pak-Fa - RCS is 0.5 m2 (from Russian Embassy in India official website citation)

References:

GlobalSecurity: Radar Cross Section (RCS)

Russian Embassy in India official website: India, Russia close to pact on next generation fighter

----------

Australia Air Power: J-20 is a "genuine Very Low Observable design"

J-20 Mighty Dragon is a "genuine Very Low Observable design" except for round engine nozzles, which can be fixed.

The Chengdu J-20: Peace in Our Time?

"This study has therefore established through Physical Optics simulation across nine radio-frequency bands, that no fundamental obstacles exist in the shaping design of the J-20 prototype precluding its development into a genuine Very Low Observable design.

Above: L-band RCS, below X-band RCS head on, both in PCSR format (M.J. Pelosi).

Engineers and Scientists who work in ‘stealth’ (AKA ‘Low Observable&#8217 designs have a way for explaining it to lay people: ‘Stealth’ is achieved by Shaping, Shaping, Shaping and Materials (Denys Overholser).

The F-22A is clearly well shaped for low observability above about 500 MHz, and from all important aspects. The J-20 has observed the ‘Shaping, Shaping, Shaping’ imperative, except for the axisymmetric nozzles, and some curvature of the sides that smears a strong, but very narrow specular return into something of a more observable fan. The X-35 mostly observed the ‘Shaping, Shaping, Shaping’ rule, but since then, to quote a colleague, ‘hideous lumps, bumps, humps and warts’ have appeared on the JSF to disrupt the shaping imperative, forcing excessive reliance on materials, which are at the rear-end of the path to ‘Low Observability’.

While discussing ‘rear-ends’, both the F-35 and the J-20 have large signature contributions from their jet nozzles. However, the difference is much like the proverbial ‘Ham Omelette’: the F-35 Pig is committed, but the J-20 Chicken is a participant. If the Chinese decide that rear sector Low Observability is tactically and strategically important, they are at the design stage where they can copy the F-22A nozzle design for the production configuration of the J-20."

[Note: Thank you to HouShanghai and 蓝胖 for the picture.]

The stimulation takes the Azm angle at 180degree while in X-band... sorry but planes don't fly on flat surfaces... any deviation from that 180degree plane would make the RCS jump like a jack in the box thanks to those extra large canards... and these days radar processors don't miss such jumps.

On a lighter note how did the RCS of J-20 come in between F-22 from front an F-35 from behind ?... Looks ?..

 

[Tracy]

Hello Tracy And Welcome

YES Canards can be stealthy but stealthy canards are usally very difficult to shape and harmonize with performance, the J-20 has planform alignment in the canards trailing and leading edges but its planforming is not as good as on other designs, its canards have leading edges aligned with the wing leading edges and their trailing edges aligned with the wing trailing edges, however the wing`s LERX is not aligned with the wing or canard so the LERX leading edge is not aligned with the wing or canard leading edges or trailing edges, this will affect its stealth and reduce its effectiveness....

The Dihedral of the canard is not aligned as the dorsal V tail with the flat sides of the fuselage and the forebody flat sides in fact is not aligned with anything, this is only an aerodynamic need, this also will reduce its stealth effectiveness.
So its planform alignment is not PERFECT.....

Thnx for replying you seems knowledgeable.
Some Sources says That J-20 engines are, not as powerful as Western Or Russian ones. Canards are there to enhance maneuverability / Agility / performance ?

 

[DARKY]

Thnx for replying you seems knowledgeable.
Some Sources says That J-20 engines are, not as powerful as Western Or Russian ones. Canards are there to enhance maneuverability / Agility / performance ?

Without canards J-20 would have to take off like a jumbo jet... yes the TVC on those Saturn engines also helps.

 

[SQ8]

Without canards J-20 would have to take off like a jumbo jet... yes the TVC on those Saturn engines also helps.

Explain through aerodynamic principles.

 

[Wet Shirt Contest]

Thnx for replying you seems knowledgeable.
Some Sources says That J-20 engines are, not as powerful as Western Or Russian ones. Canards are there to enhance maneuverability / Agility / performance ?

Yes, However the V tail if used as pitch control can enhance J20 agility in a similar way as if it was a triplane configuration, V tails can pitch the J-20 reducing the "AoA" of its canards and reducing the use of wing flaps. They can also be used as air brakes at the same time they are used for pitch control. this is not a unique ability of the J-20, the T50, YF-23, F-35, F-22 can also do it

 

[DARKY]

Explain through aerodynamic principles.

Haven't you seen a jumbo jet takeoff.

 

[SQ8]

Haven't you seen a jumbo jet takeoff.

Yes, but then again I dont think a lumbering jumbo jet is comparable to a supersonic fighter.. does Kopp think so?

 

[DARKY]

Yes, but then again I dont think a lumbering jumbo jet is comparable to a supersonic fighter.. does Kopp think so?

Really..

Let me call Kopp... He busy these days testing J-20 RCS in the special optical chamber with some China boys.

Would like posters here to SPECULATE the weight of J-20..

 

[j20blackdragon]

And for your information the Silent Eagle has the same frontal RCS as the F-35.

Jim Albaugh, who heads Boeing's defense business, told reporters in Paris on Sunday that the new F-15 offered a comparable level of stealth capability to what Washington was willing to sell to foreign military sales customers.

"We are not trying to say that this is an airplane that has full-aspect stealth capability," Albaugh said. "It doesn't. But from a front-radar cross-section, it has all the stealth that has been approved for export by the U.S. government."

Heinz first criticized how Boeing was marketing its F-15 Silent Eagle at a news conference in Washington on June 2, and also took a swipe at its radar-evading capabilities.

He said Boeing's work to reduce the frontal radar signature of the F-15 Silent Eagle would give it an edge over other fighters of its generation, but was still no match for the F-35: "You put (the new F-15) against a fifth-generation guy, the second he turns, he looks just like the Goodyear blimp."

AIRSHOW-UPDATE 1-Pentagon F-35 chief blasts Boeing comments | Reuters

 

[Tracy]

Yes, However the V tail if used as pitch control can enhance J20 agility in a similar way as if it was a triplane configuration, V tails can pitch the J-20 reducing the "AoA" of its canards and reducing the use of wing flaps. They can also be used as air brakes at the same time they are used for pitch control. this is not a unique ability of the J-20, the T50, YF-23, F-35, F-22 can also do it

ty More Question's Coming
In Other Forums Members says That A plane to be stealth must be designed "as flat as possible" (like b-2) BUT Here I have a doubt.....flat surface reflects more radar energy compared to curved or saw tooth surface Right ?