Chengdu J-20 5th Generation Aircraft News & Discussions

[gambit]

...I would like your complete Opinion the the J-20 analysis including China current Engine Achilles heel problem.

The internal combustion and jet engines are probably the two most inhospitable environments we have produced to date that we exploit for long term use.

For the internal combustion engine, we have an explosion powerful enough to deny a human being the use of a hand or foot confined inside a metal chamber that we turn into mechanical motion via a moving device called a 'piston'. The entire contraption must be durable enough to start and stop upon our whims and under varying temperatures. It must be made to suffer our abuses, from fuel grades to how we physically handle it.

Now multiply that a thousand folds for the jet engine.

How effective is the J-20 regarding its role as a tactical air superiority platform depends on its engines. We are not talking about smooth and stable movements on the throttles like an airliner but abrupt detent to detent and everywhere in the middle of those detents. The responses must be instantaneous. We must have durability but this is not the same as reliability, the latter is about maintenance that may not be under ideal hangar-ed environments. The list of engineering issues is long.

 

[Chinese Century]

I have no hostile feelings for Viet Nam if that is what you are wondering about. If anything, over the decades I have been living in the US, much of my money earned I have sent back to Viet Nam to support democracy movements.


And they still have much to learn. The Chinese do not have much respect for other Asians and their hostility to my challenges to their claims reflects that racially based contempt. In the beginning, I was respectful to them. I challenged their claims with credible sources and reasonable arguments. They did not like that. When they found out I was a Viet, the kitty claws came out. And their insults got personal and racial. I expected that.

this guy is 50 years old?

no wonder he is a frustrated old geezer spewing hate on china.

china is here, we will always be here, you dont like us, tough, learn to live with it.

i higly doubt this guy has any military background, he just seems to be a copy and paste guy.

 

[NeutralCitizen]

Thanks Gambit & ChineseTiger been a while but needed to be refreshed on this up to date info on the J-20 and Engines .

 

[NeutralCitizen]

Been reading about China WS-15, found only few sources looking for more any links would help thanks.

 

[gambit]

Thanks Gambit & ChineseTiger been a while but needed to be refreshed on this up to date info on the J-20 and Engines .

The performance profiles look like this...

So we can immediately infer with reasonable accuracy that each profile will have different rate of fuel consumption, throttle cyclings, material stresses, altitude variations and rate of, payload and their rate of discard of, turbojet or turbofan, and many other quite educated guesses. Cost is also a factor. Does it make sense to install components that are Mach capable into an engine designed for cargo aircrafts?

 

[amalakas]

Got any hard data?

you mean eyeball and rough paper calculations don't count?


aaa....

things get weirder and weirder on this forum by the day.

 

[SQ8]

Your analogy with the A-380 and B-777LR is silly. A-380 has four engines. B-777LR has only two engines.

Im actually following yours ..

 

[siegecrossbow]

Been reading about China WS-15, found only few sources looking for more any links would help thanks.

Most info regarding the WS-15 are speculative.

 

[DrSomnath999]

Most info regarding the WS-15 are speculative.

bro any recent news about WS 15

 

[gambit]

you mean eyeball and rough paper calculations don't count?


aaa....

things get weirder and weirder on this forum by the day.

The 'rough' paper is being generous. But then we should expect this sort of nonsense from our man.

 

[ChineseTiger1986]

Most info regarding the WS-15 are speculative.

Well, at least it is much more reliable than the AL-31F nonsense from the so-called big shrimps anyway.

 

[gambit]

bro any recent news about WS 15

Here is something new for the Chinese boys to learn about jet engines...

Boeing 747

The flight tests disclosed a new engine problem known as "ovalization," which cropped up only after hundreds of hours in the air. It resulted from wear in the compressor assemblies that distorted the circular cross sections of elements of the compressor into an oval shape, with loss of power and considerable increase in fuel consumption. This resulted from the engines' high thrust, which reacted against their supports and bent the engine casings. Though cure emerged in the form of a steel yoke that would stiffen the case, it took time to apply.

Axial stresses dominate in any complex structures that are circular in configuration. Constant axial stresses in a cylinder, as a jet engine is, when it is coupled into another and larger complex structures like a fuselage, give us the differences between uninstalled thrust, installed thrust, and the dreaded 'ovalization' of that cylinder or casing if the connection method is inadequate. That connection is dictated by airframe design. This effect is not visible as in if we remove an engine we would see an 'oval' opening instead of a circle at the turbine opening. The effects are reduced efficiency, increased vibrations, reduced aircraft reliability, increase maintenance in time and resources, reduced engine life, and increased odds of catastrophic failure in flight.

 

[DrSomnath999]

Here is something new for the Chinese boys to learn about jet engines...

Boeing 747

Axial stresses dominate in any complex structures that are circular in configuration. Constant axial stresses in a cylinder, as a jet engine is, when it is coupled into another and larger complex structures like a fuselage, give us the differences between uninstalled thrust, installed thrust, and the dreaded 'ovalization' of that cylinder or casing if the connection method is inadequate. That connection is dictated by airframe design. This effect is not visible as in if we remove an engine we would see an 'oval' opening instead of a circle at the turbine opening. The effects are reduced efficiency, increased vibrations, reduced aircraft reliability, increase maintenance in time and resources, reduced engine life, and increased odds of catastrophic failure in flight.

hmm interesting

but how is related to WS 15 engine ,IS it any secret info that WS 15 is also marred by such ovalization problem

 

[amalakas]

hmm interesting

but how is related to WS 15 engine ,IS it any secret info that WS 15 is also marred by such ovalization problem

no he simply implies that making jet engines is not like making pies.

 

[siegecrossbow]

Interesting new insights on the J-20 and China's potential sixth gen fighter, coming from a PLAAF Korean War ACE pilot:

Interview link: I Was There: Bring Down the Spyplane | Military Aviation | Air & Space Magazine

What do you think of China’s new J-20 stealth aircraft?

I was invited to watch the J-20’s first flight at Chengdu, and I asked the engineers a few questions. Fighter aircraft seem to have reached their maximum limits. Whether the aircraft is made in the U.S. or Russia, there is not much difference between the latest aircraft from these countries. Further development is limited by the physical stress a pilot’s body can tolerate. The U.S. is leading the way in the use of unmanned aircraft. I think there is a role for unmanned aircraft in China.