Chengdu J-20 5th Generation Aircraft News & Discussions

[Deino]

Can we leave out Japan from this discussion !

 

[j20blackdragon]

There is a direct relationship between the size of the intake, amount of airflow, and maximum thrust of the engine. Increasingly powerful engines will generally require more airflow. The entire history of aviation design backs this up.

Lockheed Martin designed both the F-16 and F-22. Lockheed Martin knows the airflow requirements for the F100/F110 versus the F119. Look at the size difference of the intakes between the F-16 and F-22. I am going to post pictures of people directly inside the intake so you can establish scale.

An airman performing an intake inspection on the F-16. Note the size of the intake.

Now look at the size of the intake for the F-22. The intake is significantly larger because the F119 has significantly greater airflow requirements to generate the extra thrust. It's that simple.

Likewise, CAC designed both the J-10 and J-20. CAC knows the airflow requirements for the AL-31 and both aircraft. CAC purposely designed the J-20 to have larger intakes than the J-10.

I'm still looking for more pictures to determine the size of the J-20 intakes. A person standing somewhere in the vicinity of the intakes helps shape your sense of scale.

Here are a couple of good ones.

I still think the J-20 intakes are massive. A full grown man can easily fit in there.

 

[j20blackdragon]

I'm still looking for more pictures to determine the size of the J-20 intakes. A person standing somewhere in the vicinity of the intakes helps shape your sense of scale.

Here are a couple of good ones.

I still think the J-20 intakes are massive. A full grown man can easily fit in there.

Compare the intake size of the Su-34 to the J-20 above. Don't forget that the Su-34 was designed for AL-31FM1. I'm sure the Russians know the airflow requirements for their own engine.

 

[Ultima Thule]

Compare the intake size of the Su-34 to the J-20 above. Don't forget that the Su-34 was designed for AL-31FM1. I'm sure the Russians know the airflow requirements for their own engine.

So what your point bro? are you saying that J-20 is using WS-15 from the beginning? another possibilty is that those huge intakes of J-20 is definitely for WS-15 but as a stop gap measures they initially intall AL-31FM1 later WS-10B with some kind of airflow diverter that divert excess airflow away from the interim engine just my 2cent

 

[Deino]

Can anyone translate ??

 

[terranMarine]

@Deino only if you use the correct map for your next book

 

[Deino]

@Deino only if you use the correct map for your next book

Good one ! But like I already noted, maybe You should give such a correct map I can use as a basis in order to avoid any more mistakes ? Just a link to such a map would be fine enough.

 

[j20blackdragon]

Su-30MKM with a bunch of people standing around it. We even have guys sitting on the aircraft tow tractor in front of the aircraft. Note the intake size.

J-20

The intake size difference could not be more obvious.

 

[Asoka]

Su-30MKM with a bunch of people standing around it. We even have guys sitting on the aircraft tow tractor in front of the aircraft. Note the intake size.

J-20

The intake size difference could not be more obvious.

I think the point, you are trying to make, is that even the new plane is designed with the new and more powerful engine in mind, but also allow an older and weaker engine to fit, in order to get it to fly first. Suppose that actually works.

The old engine with weaker power and less air intake requirement, will not adequately test the plane to its limit, therefore, when the new and much more powerful engine is ready, all the tests must be performed again.

So it is not simply loose several screws and poop in the new engine, and there you go and everything will be fine.

The new and more powerful engine and plane, must be tested all over again, like in a new plane.

I think this is point that non-technical people don't get.

 

[j20blackdragon]

I think the point, you are trying to make, is that even the new plane is designed with the new and more powerful engine in mind, but also allow an older and weaker engine to fit, in order to get it to fly first. Suppose that actually works.

The old engine with weaker power and less air intake requirement, will not adequately test the plane to its limit, therefore, when the new and much more powerful engine is ready, all the tests must be performed again.

So it is not simply loose several screws and poop in the new engine, and there you go and everything will be fine.

The new and more powerful engine and plane, must be tested all over again, like in a new plane.

I think this is point that non-technical people don't get.

Yes.

Let me just give an analogy.

J-20 with AL-31 is like the picture below.

The shoe is the airframe.

The kid's foot is the engine.

The inside of the shoe is the engine bay.

Forcing this kid to run around with these oversized shoes is a pointless test.

No engineer in his right mind would conduct a test like this.

The PLA would not accept this kid into the army.

 

[samsara]

Yes.

Let me just give an analogy.

J-20 with AL-31 is like the picture below.

The shoe is the airframe.

The kid's foot is the engine.

The inside of the shoe is the engine bay.

Forcing this kid to run around with these oversized shoes is a pointless test.

No engineer in his right mind would conduct a test like this.

The PLA would not accept this kid into the army.

I must say that your analogy furnished with the matched illustration is thought provoking (as well as your many posts above)... and the picture itself is amusing

 

[ptldM3]

The Mig-25 produced only 22,400 lbs thrust in afterburners and it has the biggest intakes of any single seat aircraft.

Intake size and the intake channel are two different things. The intake channels in serpentine designs is not as large as the intake suggests.

 

[lcloo]

And don't forget the air bleeding vanes on the air intake which varies volume of air flow into engine.

 

[j20blackdragon]

The Mig-25 produced only 22,400 lbs thrust in afterburners and it has the biggest intakes of any single seat aircraft.

Intake size and the intake channel are two different things. The intake channels in serpentine designs is not as large as the intake suggests.

View attachment 386849

I would like to compare apples to apples.

The MiG-25 is an interceptor, powered by turbojet engines, designed in the 1960s. It had variable geometry intakes with adjustable intake ramps to regulate the speed and volume of airflow, and shock wave formation.

The Tumansky R-15 engines are massive.

Type: Afterburning turbojet
Length: 6,264 mm (246.6 in)
Diameter: 1,512 mm (59.5 in)
Dry weight: 2,454 kg (5,410 lb)

https://en.wikipedia.org/wiki/Tumansky_R-15

The MiG-25 was big all the way through, from intakes to nozzles.

The turbojet engine had very high fuel consumption, which requires large amounts of air.

I would like to compare the J-20 to 4th or 5th generation fighter jets, with turbofan engines, with fixed intakes.

My 'intake size' rule is really just a rule of thumb, but still a very good rule. In most instances, the engine with higher thrust will have a larger intake. There will always be exceptions to the rule.

 

[Ultima Thule]

I would like to compare the J-20 to 4th or 5th generation fighter jets, with turbofan engines, with fixed intakes.

J-20 have variable or adjustable DSI intakes as per @wanglaokan, @ChineseTiger1986, and @Beast bro

Yes.

Let me just give an analogy.

J-20 with AL-31 is like the picture below.

The shoe is the airframe.

The kid's foot is the engine.

The inside of the shoe is the engine bay.

Forcing this kid to run around with these oversized shoes is a pointless test.

No engineer in his right mind would conduct a test like this.

The PLA would not accept this kid into the army.

So what your point bro? are you saying that J-20 is using WS-15 from the beginning? another possibility is that those huge intakes of J-20 is definitely for WS-15 but as a stop gap measures they initially install AL-31FM1 later WS-10B with some kind of airflow diverter that divert excess airflow away from the interim engine just my 2cent