Chinese Engine Development

weig2000 · Mar 28, 2023

latenlazy said:
It would be unrealistic, and frankly unreasonable, to expect the WS-15 to *exceed* the F135 or F119. Frankly it's already pretty monumental for the WS-15 to be in the same ballpark. At this point even if there is still a gap between the WS-15 and F135 it's not going to be a very big one. The WS-15 we are getting today is likely *way* more advanced than whatever they were planning to introduce back in the late 2000s.

The impression I've gotten following this topic for a decade now is that after the debacle that was the WS-10's initial introduction they went back to the drawing board for the WS-15's development and waited for critical enabling component technologies to mature before being satisfied with the design. The just get something out the door mentality was a necessity when China was backwards and poor and needed to have something just to maintain a bare minimum capability, but they've now figured out it is an absolutely terrible way to chase the technology frontier. Your designs have to come from much more advanced fundamental components and technologies, and the brunt of your energy and resources need to focus on those foundations if you want to chase cutting edge performance.

If you focus your resources on advancing your component technologies and make your design and product development process downstream of that your product development moves very quickly. If one component or another fails you will have a portfolio of other components to try to maintain a fast rate of iteration on your design. Furthermore, components development itself can iterate much faster on their own than if they're contingent on a larger integrated design stack. If you start with a design and then make component technologies downstream of that you will be forced to redo the whole development stack every time a component fails, since you will have to redevelop new components and wait on those to hit those design goals. The latter approach has only one superficial advantage to the former, which is that it is on paper cheaper. But even that advantage bleeds very quickly once you start hitting project delays. The lesson that product design has to come downstream from components and not vice versa has been critical for China's ability to close the technology gap. Rapid advanced product development cannot work without good optionality in your component technologies. This is why we are now seeing new engine developments happening so rapidly. The dam has finally broken loose.

One of the more important changes in China's aircraft engine development strategy is to separate the engine development from the aircraft development, which reflected in the formation/spin-off of AECC from AVIC. This is somewhat similar to your arguments about the detachment of component technologies development from the product development.

This was one of the key lessons that China learned in the decades of development experience of their aircraft industry. Before, development of each new aircraft engine was bundled with the development program of a new aircraft. Since aircraft engine development cycle is different from and usually longer than the aircraft development cycle. The results of this packaged development programs were that either the new aircraft flew without the intended engine or the cancellation of the aircraft engine development due to canceled aircraft program. Either way, the development of aircraft engines were stalled or stunted. A lot of these were due to lack of funding and China being poor and all that.

Now, aircraft engines have their own development cycles and roadmaps, and AECC can plan and invest in materials, components and product development at their own pace. Over time, this strategy has borne fruit and it has become a positive reinforcing loop between aircraft development and aircraft engine development. This is reflected in the generations and families of aircraft engines (WS-10A/B/C, WS-15; WS-13/WS-21, WS-19; WS-18, WS-20, CJ1000A, CJ2000, 5-generation engine etc.) and generations of aircraft (J-10/J-11B/J-16/J-20A/J-20B; J-31/J-35, Y-20A/Y-20B, C919, C929, 6-gen aircraft etc.).

latenlazy · Mar 28, 2023

weig2000 said:
One of the more important changes in China's aircraft engine development strategy is to separate the engine development from the aircraft development, which reflected in the formation/spin-off of AECC from AVIC. This is somewhat similar to your arguments about the detachment of component technologies development from the product development.

This was one of the key lessons that China learned in the decades of development experience of their aircraft industry. Before, development of each new aircraft engine was bundled with the development program of a new aircraft. Since aircraft engine development cycle is different from and usually longer than the aircraft development cycle. The results of this packaged development programs were that either the new aircraft flew without the intended engine or the cancellation of the aircraft engine development due to canceled aircraft program. Either way, the development of aircraft engines were stalled or stunted. A lot of these were due to lack of funding and China being poor and all that.

Now, aircraft engines have their own development cycles and roadmaps, and AECC can plan and invest in materials, components and product development at their own pace. Over time, this strategy has borne fruit and it has become a positive reinforcing loop between aircraft development and aircraft engine development. This is reflected in the generations and families of aircraft engines (WS-10A/B/C, WS-15; WS-13/WS-21, WS-19; WS-18, WS-20, CJ1000A, CJ2000, 5-generation engine etc.) and generations of aircraft (J-10/J-11B/J-16/J-20A/J-20B; J-31/J-35, Y-20A/Y-20B, C919, C929, 6-gen aircraft etc.).

Modularity is good for technology development who knew!

siegecrossbow · Mar 28, 2023

Michaelsinodef said:
The most funny part in the article, is probably how about, it's the western companies, where their leaders and managers can't let go of power and give more power to people lower down.

While in China, they are able to do precisely that.

And well, what is it again that they are always spouting about China in western MSM? Something about control? Power concentrated at the top? No power to ordinary people? Leaders hogging power yada yada?

While I do know it's more directed at the political side, but the idea that there aren't such thoughts and remarks about Chinese businesses would be very wrong (oh yea, also probably lots of it aimed at state owned enterprises).

Hikvision is stated owned and Norfolk Southern is private. Management, not whether a firm is state or private owned, determines the level of success.

BoraTas · Mar 28, 2023

manqiangrexue said:
I thought supercruise is to save fuel and increase range by going supersonic without using afterburners? Why does it guzzle gas if it doesn't activate afterburners?

It is. Afterburners are less efficient because they utilize a hotter, faster, and less pressurized stream compared to the main burner.

But it is impossible to say how J-20's fuel consumption per km traveled will change without knowing things like lift coefficient over different speeds, drag coefficient over different speeds, air inlet pressure recovery over different speeds, how the WS-15's efficiency scale with different air inlet pressures, etc...

A typical aircraft drag coefficient - mach number graph looks like this. This is for same altitude and level flight

It first falls down as you increase your speed (because you need less angle of attack to maintain the altitude) then it starts going up because of compressibility. There is a huge spike over the transonic area. Then it continues falling until the hypersonic region. This is the general trend. Specifics can change a lot depending on the airframe shape. And mind you this is just the drag coefficient which you multiply with the square of your velocity and air density. So the drag is actually always increasing (for the same altitude) but it actually increases quite slowly between Mach ~1 and Mach ~1.6 as you leave the transonic spike behind. Most fighters need just 10-20% or so more thrust to increase their speed from Mach 1 to Mach 1.5. This combined with extra efficiency enabled by the ram effect and extra altitude enabled by extra lift can actually mean less fuel consumption by km traveled. Transonic spike is why aircraft top speeds are either subsonic or Mach 1.5+ Designing a supersonic aircraft that can't push beyond the transonic spike would be foolish.

The SR-71 had its lowest fuel consumption per km point at Mach 3.2! At very low speeds its engine had low efficiency (low compression ratio) and it couldn't achieve good altitudes. At low supersonic speeds, its drag coefficient was high, the engine was still not very efficient and altitudes were still not high. At Mach 3.2 engine was working with a pressure ratio of well over 110, altitudes were very high, and the drag coefficient was low. All of these meant the aircraft had its lowest consumption point at Mach 3.2.

Lift to drag ratios of different shapes over different mach numbers

So the answer is: The J-20 might guzzle gas while supercruising or it might not. Impossible to say without further data.

siegecrossbow · Mar 28, 2023

weig2000 said:
One of the more important changes in China's aircraft engine development strategy is to separate the engine development from the aircraft development, which reflected in the formation/spin-off of AECC from AVIC. This is somewhat similar to your arguments about the detachment of component technologies development from the product development.

This was one of the key lessons that China learned in the decades of development experience of their aircraft industry. Before, development of each new aircraft engine was bundled with the development program of a new aircraft. Since aircraft engine development cycle is different from and usually longer than the aircraft development cycle. The results of this packaged development programs were that either the new aircraft flew without the intended engine or the cancellation of the aircraft engine development due to canceled aircraft program. Either way, the development of aircraft engines were stalled or stunted. A lot of these were due to lack of funding and China being poor and all that.

Now, aircraft engines have their own development cycles and roadmaps, and AECC can plan and invest in materials, components and product development at their own pace. Over time, this strategy has borne fruit and it has become a positive reinforcing loop between aircraft development and aircraft engine development. This is reflected in the generations and families of aircraft engines (WS-10A/B/C, WS-15; WS-13/WS-21, WS-19; WS-18, WS-20, CJ1000A, CJ2000, 5-generation engine etc.) and generations of aircraft (J-10/J-11B/J-16/J-20A/J-20B; J-31/J-35, Y-20A/Y-20B, C919, C929, 6-gen aircraft etc.).

It is a conundrum really. Engine makers are poor because they can't generate revenue by selling engines to the military. Without money, they can't develop a good engine. And the cycle continues.

latenlazy · Mar 28, 2023

siegecrossbow said:
It is a conundrum really. Engine makers are poor because they can't generate revenue by selling engines to the military. Without money, they can't develop a good engine. And the cycle continues.

Engine makers share a lot of industrial equipment and components with other mechanical engineering fields. You let the revenue and capital development of other mech e fields give you the resources to pursue engine development. This is how every other jet engine company got their start. No one *starts* with the jet engine.

kurutoga · Mar 28, 2023

TK3600 said:
Zzz. American engine development hardly moved after 20 years from 2000s. Just need some iterative development on WS-15 and you are at today's level. Shocking I know. The 20 year gaps are not equal. 40 year gap vs 20 year gap is a huge gap. 20 year to today is nothing.

I don't want to shit on the US MIC. However, from the outside looking in, they seem have lost the "pizzazz". Was it a generational thing because old guys retired, or was just a cultural shift starting from schools. From the F-35 projects, even though they are quite successful, you see they paid more attention to the form than the substance. And, the top-down political pressure was huge in forming such projects. How are they going to fight over some projects span longer than one's career, so that no one can take credit for?

Let's just hope the new fighter jets of the 2030s (both AF and Navy) can regain some vigor. While I am strictly anti-war, I'd like to see some nice war machines though

gelgoog · Mar 28, 2023

I think you guys are overstating things a bit. While China was at one point behind in jet engine technology by like 30 years, and now the difference is more like 20 years, it is not true that China was still using turbojets 20 years ago. They had the Rolls-Royce Spey turbofan in production aka WS-9. Significant changes happened since 20 years ago, and you see them in commercial engines. Composite fan blades, 3D printed engine components, and ceramic composites for example. While it is heartening to see Chinese advance in jet engine technology it will still take some time for China to catch up. All of this is also assuming the WS-15 is production ready but we still have not seen it in use in any production aircraft.

latenlazy · Mar 28, 2023

gelgoog said:
I think you guys are overstating things a bit. While China was at one point behind in jet engine technology by like 30 years, and now the difference is more like 20 years, it is not true that China was still using turbojets 20 years ago. They had the Rolls-Royce Spey turbofan in production aka WS-9. Significant changes happened since 20 years ago, and you see them in commercial engines. Composite fan blades, 3D printed engine components, and ceramic composites for example. While it is heartening to see Chinese advance in jet engine technology it will still take some time for China to catch up. All of this is also assuming the WS-15 is production ready but we still have not seen it in use in any production aircraft.

The Chinese jet engine industry has composite fan blades, 3D printed engine components, and ceramic composites today.

Blitzo · Mar 28, 2023

gelgoog said:
I think you guys are overstating things a bit. While China was at one point behind in jet engine technology by like 30 years, and now the difference is more like 20 years, it is not true that China was still using turbojets 20 years ago. They had the Rolls-Royce Spey turbofan in production aka WS-9. Significant changes happened since 20 years ago, and you see them in commercial engines. Composite fan blades, 3D printed engine components, and ceramic composites for example. While it is heartening to see Chinese advance in jet engine technology it will still take some time for China to catch up. All of this is also assuming the WS-15 is production ready but we still have not seen it in use in any production aircraft.

WS-9/Spey itself was hardly a cutting edge engine for that time (and it wasn't even semi-modern by then), and more importantly it wasn't developed on a wholly domestic basis like the other projects.

In terms of the extent of overall aeroengine industry in terms of both development and production, in all aspects whether it is technology or project management, I don't think it is an exaggeration at all to say that the difference between the current aeroengine industry with global leaders, versus the difference of China's aeroengine industry to global leaders 20 years ago, that there's been significant closure. A significant gap still exists, but it's not the kind of near insurmountable gap that looked apparent at the time.

The lessons learned over the last 20 years and accumulation of institutions and technology is very significant, because 20 years ago it was almost close to -nothing-.

Chinese Engine Development

weig2000

Captain

latenlazy

Brigadier

siegecrossbow

General

BoraTas

Captain

siegecrossbow

General

latenlazy

Brigadier

kurutoga

Junior Member

gelgoog

Lieutenant General

latenlazy

Brigadier

Blitzo

Lieutenant General