Chengdu J-20 5th Generation Aircraft News & Discussions

[Deino]

1.) Just as I thought I was done with figuring out the length and width of J-20, I have a persistent urge to verify and confirm, whether the actual wingspan of J-20 is: 13.47m, as stated in the blurry low resolution satellite picture.

2.) To improve the possibility of a better estimate, I took the blurry picture, which was only about 300 pixels across, and resized it to 800%.

3.) This would allow me to view the resultant picture, across my 27 Inch screen, in its new size, and apply the thinnest red lines, that the iMac Preview would allow.

View attachment 427129

4.) Using the J-15's wingspan of 14.7m as scale, I resized the Metric meter, so the 14.7m falls exactly between the redlines of J-25's wingspan.

5.) I then copied the metric meter image and applied it to the J-20 wingspan.

6.) It yielded the new wingspan value of 14.0m for J-20, which is about 58cm longer than the old value of 13.47m.

7.) I noticed that J-20 was not parked exactly parallel to J-15, but slightly tilted to the left. So I used the Pythagorean theorem to adjust the value to 14.05m.

8.) J-15's wingspan is indeed longer than J-20's wingspan, but its only 0.42m longer, not 1.10m.

9.) The new wingspan values still have rooms for doubts or improvement, since the estimate is based on original low resolution satellite picture, that is extremely blurry.

Intesting approach but why not simply calculating the J-20's length directly from this enlarged image?

IMO sizing the image to calculate span only to then resize and upscale another image adds a larger margin of error than to measure directly.

J-20B? Too bad no backside ...

A CG only.

 

[Asoka]

Intesting approach but why not simply calculating the J-20's length directly from this enlarged image?

IMO sizing the image to calculate span only to then resize and upscale another image adds a larger margin of error than to measure directly.



A CG only.

The wingspan is clearly delineated even in this blurry image, but the nose and nozzle area are simply too indistinct to apply the thin red lines.

Once, we got the wingspan, and assuming it stays the same, we could obtain the length from other pictures. I noticed that the later models has a longer tailboom, than version 2001.

So the overall length for the LRIP planes is actually 23m, which is the about same as the F-111, and the nose and nozzle measurement is about the same too.

What a coincident!

Those Lockeed Engineers are no ordinary guys. They have figured out the optimum shape for a large, high speed, supersonic, twin engined fighter, over 50 years ago.

F-111 General characteristics

• Crew: two (pilot and weapon systems officer)
• Length: 73 ft 6 in (22.4 m)
• Wingspan:
  • Spread: 63 ft (19.2 m)
  • Swept: 32 ft (9.75 m)
• Height: 17.13 ft (5.22 m)
• Wing area:
  • Spread: 657.4 sq ft (61.07 m²)
  • Swept: 525 sq ft (48.77 m²)
• Airfoil: NACA 64-210.68 root, NACA 64-209.80 tip
• Empty weight: 47,200 lb (21,400 kg)
• Loaded weight: 82,800 lb (37,600 kg)
• Max. takeoff weight: 100,000 lb (45,300 kg)
• Zero-lift drag coefficient: 0.0186[177]
• Drag area: 9.36 sq ft (0.87 m²)
• Aspect ratio: spread: 7.56, swept: 1.95
• Powerplant: 2 × Pratt & Whitney TF30-P-100 turbofans
  • Dry thrust: 17,900 lbf (79.6 kN) each
  • Thrust with afterburner: 25,100 lbf (112 kN) each

 

[Deino]

The wingspan is clearly delineated even in this blurry image, but the nose and nozzle area are simply too indistinct to apply the thin red lines.

Once, we got the wingspan, and assuming it stays the same, we could obtain the length from other pictures. I noticed that the later models has a longer tailboom, than version 2001.

So the overall length for the LRIP planes is actually 23m, which is the about same as the F-111, and the nose and nozzle measurement is about the same too.

What a coincident!

Those Lockeed Engineers are no ordinary guys. They have figured out the optimum shape for a large, high speed, supersonic, twin engined fighter, over 50 years ago.

Honestly ... You are such an idiot !

The only reason - and in fact a very lame excuse - that You chose Your plain incorrect variant was, since it again fit's nicely Your mega-long version.

Even if a direct measurement from that grainy image would include an error it would never ever result in a length larger than the J-15 exactly standing a few meters aside ....

 

[leapx]

View attachment 427130

1.) By using the new wingspan estimate of 14.05m for J-20, I applied the same method to find the length as before.

2.) This yielded the following:

a.) Overall Length, J-20: 22.8m, F-22: 18.8m, Difference: 4.0m, or 21.3% longer
b.) Nose to Nozzle length, J-20: 21.7m, F-22: 16.7m, Difference: 5.0m, or 29.94% longer

That is from nose to nozzle J-20 is 5 meters, or nearly 30% longer than F-22.

Those extra 5 meters long fuselage could give J-20 enormous volume to store extra internal fuel.

The F-111's length is similar to J-20, but probably has wider fuselage, it has "Fuel tanks were distributed through the fuselage and in the wings, providing a total fuel load of over 19,000 liters (5,000 US gallons) or 18.56 tons." --http://www.airvectors.net/avf111.html

Like F-22, F-111 and J-20 also have a large internal weapon bay, so the amount of space taken up for such purpose should be similar.

J-20 definitely has a much greater internal fuel capacity than F-22's 8 tons. It's internal fuel capacity is probably in the range of 12-15 tons, or 50-87.5% more than F-22's 8 tons.

This is not yet including the 4 external fuel tanks, which could add another 8 tons of fuel.

This is totally astounding and mind boggling.

Note the Combat Range of F-111 is 2,140km, and Ferry range is: 6,760 km, Max. Speed is: Mach 2.5 . J-20's performance should be no less than that.

F-111 Performance

• Maximum speed: Mach 2.5 (1,650 mph, 2,655 km/h)
• Combat radius: 1,330 mi (1,160 nmi, 2,140 km)
• Ferry range: 4,200 mi (3,700 nmi, 6,760 km)
• Service ceiling: 66,000 ft (20,100 m)
• Rate of climb: 25,890 ft/min (131.5 m/s)
• Wing loading: ** Spread: 126.0 lb/ft² (615.2 kg/m²)
  • Swept: 158 lb/ft² (771 kg/m²)
• Thrust/weight: 0.61
  
• Lift-to-drag ratio: 15.8

Powerplant: 2 × Pratt & Whitney TF30-P-100
Lat turbofans

• Dry thrust: 17,900 lbf (79.6 kN) each
• Thrust with afterburner: 25,100 lbf (112 kN) each

J-20 will be powered by two an amazingly powerful engines, WS-15, capable of, at least 210kN, of Maximum thrust, which is 100kN more than F-111's PW TF30-P-100's 112 kN.

I would bet J-20 and F-22 (because of their powerful engines, and highly aerodynamic airframes, with high lift-to-drag ratio) will be able to fly a lot faster's F-111's top speed of Mach 2.5 (F-111's highly swept back wings, allow it to have this kind of super fast performance).

Because of it long and slender shape, J-20 could possibly capable of cruising, beyond Mach 3.0, with its afterburner turned on.

Why do you assume 210KN？ I myself is an aero-engine engineer.I worked in a AVIC research institution for 5 years followed by 4 years as CFM56 engineer in a CFMI-sino maintenance shop. 210KN is a ridiculous number

 

[Asoka]

Honestly ... You are such an idiot !

The only reason - and in fact a very lame excuse - that You chose Your plain incorrect variant was, since it again fit's nicely Your mega-long version.

Even if a direct measurement from that grainy image would include an error it would never ever result in a length larger than the J-15 exactly standing a few meters aside ....

"You chose Your plain incorrect variant was, since it again fit's nicely Your mega-long version."

The new LRIP's model dimension is basically the same as the version 2001. The difference is that the LRIP has a noticeably longer tailboom extended past the canted vertical tail, and that gives it a slightly longer overall length.

The Nose and Nozzle length stays the same.

In the picture above, I did not copy and past an image of a metric ruler onto the J-20, since I can not rotate the ruler precisely to align with the red lines. iMac's Preview program only allows me to rotate left or right, not at a precise angle.

I basically measure the wingspan, nose and nozzle length, and overall length, with a tape measure, on my computer screen, and then compute their ratios and multiple it with the wingspan value of 14.05m.

It's easy to see that the new LRIP birds have a longer tailboom than version 2001, so that its overall length has increased from to 22.8m to 23.06m

"Even if a direct measurement from that grainy image would include an error it would never ever result in a length larger than the J-15 exactly standing a few meters aside ...."

As I have said before, The nose and nozzle areas are so indistinct, I have absolutely no confidence of the lengths, obtained from the satellite pictures.

I challenge everyone to verify the my findings, by using the wingspan of 14.05m obtained from the satellite picture, and then use the same picture, I have used, and follow the same procedures, i have used, to obtain the lengths of J-20.

Note: it's very important to keep the dimension, in the same proportion, as you resize a picture. Drag only by the corners, not along the width or length.

 

[ptldM3]

OMG .. Asoka again at his best.

+210 kN minimum thrust... Mach 3....

OMG

But....there is more. "Long and slender" now equates to Mach 3 flight and he thinks the J-20 is slender

The guy has never heard of a Mig-25. The aircraft is 'fat', and has suprinsingly week engines. The guy know zilch about aviation. He is making a mockery out of aviation and his claims are pure fanboy fantasy. His claims such 210km+ engines are nonsense, his claims that long and slender aircraft can reach Mach 3 is nonsense.

The guy didn't even know what vertical stabilizers were when he saw the J-20 use them. Naturally he started bragging to everyone that the J-20 was doing some super unique maneuver when in fact it just used its vertical stabilizers.

 

[Asoka]

Why do you assume 210KN？ I myself is an aero-engine engineer.I worked in a AVIC research institution for 5 years followed by 4 years as CFM56 engineer in a CFMI-sino maintenance shop. 210KN is a ridiculous number

Oh good, I finally have someone, who knows jet engine, to talk about jet engines, with me. I hope you are honest with your qualifications. I have no formal training or working experiences, in aeronautical engineering.

I am self-taught, by reading everything, I can find on jet engines and particularly WS-15, and my learning is only 1 year long, so far.

I have posted my reasoning on how I arrived at the figure 210kN, many times already. If you search "210kN" and posts made by me, you will have many hits.

 

[Figaro]

But....there is more. "Long and slender" now equates to Mach 3 flight and he thinks the J-20 is slender

The guy has never heard of a Mig-25. The aircraft is 'fat', and has suprinsingly week engines. The guy know zilch about aviation. He is making a mockery out of aviation and his claims are pure fanboy fantasy. His claims such 210km+ engines are nonsense, his claims that long and slender aircraft can reach Mach 3 is nonsense.

The guy didn't even know what vertical stabilizers were when he saw the J-20 use them. Naturally he started bragging to everyone that the J-20 was doing some super unique maneuver when in fact it just used its vertical stabilizers.

S

Intesting approach but why not simply calculating the J-20's length directly from this enlarged image?

IMO sizing the image to calculate span only to then resize and upscale another image adds a larger margin of error than to measure directly.



A CG only.

It would be interesting if the CG had sawtooth nozzles like the WS-15 or WS-10X ...

 

[leapx]

Oh good, I finally have someone, who knows jet engine, to talk about jet engines, with me. I hope you are honest with your qualifications. I have no formal training or working experiences, in aeronautical engineering.

I am self-taught, by reading everything, I can find on jet engines and particularly WS-15, and my learning is only 1 year long, so far.

I have posted my reasoning on how I arrived at the figure 210kN, many times already. If you search "210kN" and posts made by me, you will have many hits.

View attachment 427485

I can not tell anything about my work in the research institutions. It may get me into trouble. but I try to tell something about CFM56 and why I think 210 KN is ridiculous.

CFM-56 engine can be used at different thrust rating.
CFM56-3 use hydraulic-mechanical control, thrust changing need to replace some parts.
CFM56-5&-7 use FADEC so no parts need to be replaced. there is a plug for engine definition connected to ECU(basic a control unit). Adjust the plug will tell the ECU how much thrust we want then computer will take care of everything.

What real the engine do is to adjust the fuel sprayed into the core engine，so to change the energy out of core engine , thus change the speed of Low pressure turbine. Low pressure turbine drive fan to produce most thrust.
For CFM56-7 , more than 75% thrust is produced by fan on ground.

I need to sleep now . I will try to answer on the J-20 engine thread if I get the time.

 

[Asoka]

I can not tell anything about my work in the research institutions. It may get me into trouble. but I try to tell something about CFM56 and why I think 210 KN is ridiculous.

CFM-56 engine can be used at different thrust rating.
CFM56-3 use hydraulic-mechanical control, thrust changing need to replace some parts.
CFM56-5&-7 use FADEC so no parts need to be replaced. there is a plug for engine definition connected to ECU(basic a control unit). Adjust the plug will tell the ECU how much thrust we want then computer will take care of everything.

What real the engine do is to adjust the fuel sprayed into the core engine，so to change the energy out of core engine , thus change the speed of Low pressure turbine. Low pressure turbine drive fan to produce most thrust.
For CFM56-7 , more than 75% thrust is produced by fan on ground.

I need to sleep now . I will try to answer on the J-20 engine thread if I get the time.

I don't know anything about CFM56, not even just casual reading about it. We are talking about WS-15 for J-20 here, not WS-10X.

210kN is actually not ridiculous enough. This is a lower bound estimate I got for WS-15. I am afraid to tell what's really in my mind, for spilling out China State Military secrets.

It takes nothing for them to find out who I am. Some days, I want to go back to China.

 

[leapx]

I don't know anything about CFM56, not even just casual reading about it. We are talking about WS-15 for J-20 here, not WS-10X.

210kN is actually not ridiculous enough. This is a lower bound estimate I got for WS-15. I am afraid to tell what's really in my mind, for spilling out China State Military secrets.

It takes nothing for them to find out who I am. Some days, I want to go back to China.

I am not just talk about CFM56, I try to tell you how to increase the thrust of an engine.
But you are too much being yourself.

 

[Figaro]

I am not just talk about CFM56, I try to tell you how to increase the thrust of an engine.
But you are too much being yourself.

Ignore him ... he won’t listen to you. Besides, he says 210kN is a “low” estimate, saying that 240 is more probable. As I say, he is delusional

 

[Deino]

1.) Just as I thought I was done with figuring out the length and width of J-20, I have a persistent urge to verify and confirm, whether the actual wingspan of J-20 is: 13.47m, as stated in the blurry low resolution satellite picture.

2.) To improve the possibility of a better estimate, I took the blurry picture, which was only about 300 pixels across, and resized it to 800%.

3.) This would allow me to view the resultant picture, across my 27 Inch screen, in its new size, and apply the thinnest red lines, that the iMac Preview would allow.

View attachment 427129

4.) Using the J-15's wingspan of 14.7m as scale, I resized the Metric meter, so the 14.7m falls exactly between the redlines of J-25's wingspan.

5.) I then copied the metric meter image and applied it to the J-20 wingspan.

6.) It yielded the new wingspan value of 14.0m for J-20, which is about 58cm longer than the old value of 13.47m.

7.) I noticed that J-20 was not parked exactly parallel to J-15, but slightly tilted to the left. So I used the Pythagorean theorem to adjust the value to 14.05m.

8.) J-15's wingspan is indeed longer than J-20's wingspan, but its only 0.42m longer, not 1.10m.

9.) The new wingspan values still have rooms for doubts or improvement, since the estimate is based on original low resolution satellite picture, that is extremely blurry.

Again; Your estimation is plain wrong and I think I only answer Your false estimation since it includes at least a good start.
So .. even if blurred and surely not exactly the same angle, I used Your fine-rotated J-20 and set it exactly besides the J-15. It seems as if this GE image seems to be a bit distorted in length to span, since given the span-calculation the J-15 should be 792 pixels long, what simply never fits.
Therefore I used the same scale in pan to calculate the J-20's span and the J-15's length to calculate the J-20's length, which in order to give a few feet by were set quite long behind the nozzle. I order to estimate the length I used a few characteristic shadows which must be angled the same and come to the following estimations/calculations:

Span 13.90m
Length 20.48m

FACT again: the J-20

 

[Michael Corleone]

I dont know what carbon titanium based composites is.
there was some discussion about material used in J-20
20% titanium，29% composites.

so it's not a fully composite based aircraft (superstructure and outer fuselage) like the f-22 or f-35?

 

[Asoka]

Again; Your estimation is plain wrong and I think I only answer Your false estimation since it includes at least a good start.
So .. even if blurred and surely not exactly the same angle, I used Your fine-rotated J-20 and set it exactly besides the J-15. It seems as if this GE image seems to be a bit distorted in length to span, since given the span-calculation the J-15 should be 792 pixels long, what simply never fits.
Therefore I used the same scale in pan to calculate the J-20's span and the J-15's length to calculate the J-20's length, which in order to give a few feet by were set quite long behind the nozzle. I order to estimate the length I used a few characteristic shadows which must be angled the same and come to the following estimations/calculations:

Span 13.90m
Length 20.48m

View attachment 427493



FACT again: the J-20

Your finding of the J-20's wingspan to be 13.9m, I have no problem with. The difference is within the error of margin with my finding of 14.05m.

I still have great reservations about, where to place the lines, on the nose and on the tail. It's just too blurry on those area. Sorry. I don't have any confidence on the lengths obtained from the satellite.

I am glad to see that you are trying to confirm or disprove my findings by actual researches.