Chinese Engine Development

Quickie

Major
On the interesting points Taxiya raised about reaching supersonic speeds with only dry thrust. He is more or less correct except breaking the sound barrier imposes a dramatic increase in drag. This means the aerodynamics of the fighter comes into greater play. Since we don't know the specifics here and we can't eyeball it, it's impossible to say whether or not the flanker series can supercruise even if their engines are not stopping them from doing so.
That is correct.

If I may rephrase it. "it's impossible to say whether or not the flanker series can supercruise if their engines' thrust-to-weight ratio is above or below a certain value.
 

SamuraiBlue

Captain
Correct. This is why I described continued supersonic speeds as a different problem to just thrust to weight ie a thrust issue for these fighters.

Since we don't understand the aerodynamic profiles of flanker and J-20, we shouldn't speculate. This author of the article is in a more ignorant position.
Again wrong.
Since weight to thrust ratio is the biggest factor in determining top speed since excess thrust required to accelerate the plane is determined by newton's second law.

 

Quickie

Major
Without afterburner?
I doubt it and if it can't then it can't supercruise. Simple as that.
To maintain speed within constant resistance(drag) against a moving object means it requires constant acceleration.
Huh? Acceleration is zero when the speed is constant. With constant acceleration, the object's speed changes with time at a constant rate.
 

Quickie

Major
Again wrong.
Since weight to thrust ratio is the biggest factor in determining top speed since excess thrust required to accelerate the plane is determined by newton's second law.

The graphic is showing the aircraft in an "Excess Thrust" condition i.e. the aircraft is accelerating.

When there's no excess thrust, Thrust = Drag, the aircraft is maintaining a constant speed.
 
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ougoah

Senior Member
Registered Member
Again wrong.
Since weight to thrust ratio is the biggest factor in determining top speed since excess thrust required to accelerate the plane is determined by newton's second law.

Mate. READ what I wrote. I said you were correct in stating the highlighted bold part.

upload_2019-10-12_17-50-59.png

So how am I wrong? Unless you are wrong since I'm quoting and agreeing with the bold and boxed statement above.
 

Attachments

ougoah

Senior Member
Registered Member
Lol at Samurai's "physics"...

And for the record thrust IS a big factor. No one said it isn't. Again try get comprehension right before attempting physics. It's easier.

There is something called equilibrium. When an applied force results in a net in forwards acceleration, then it doesn't need to continue pushing beyond this thrust to accelerate forwards BUT the drag increases non linearly so it DOES in reality require more thrust to overcome this increasing drag. How much more is complex to calculate for us here and impossible with zero data. Where these points lie do factor in overall aerodynamic drag coefficient (which is very complex and dynamic since a fighter changes geometry and altitude) and lift among other things like angle of attack etc.

The NASA diagram is great ... for high school kids to get a VERY basic fundamental understanding of this concept. It doesn't even touch fluid concepts. This is not the be all end all of aircraft forces. And even if it is, we need NUMBERS to work with. If you disagree with any of the above, please write out a detailed model of your version of how you think supercruising works. I'm happy to embarrass you.

Again I'll say it once more. Thrust IS a big factor. Nobody denies this. But this thrust part came out of nowhere in the conversation. The article is technically incorrect in many respects. It therefore loses its reputation. That's all there was to it.

On the subject of supercruising. No one here even with an engineering background knows whether the J-20 can supercruise or not. And if it does, how "well" it can supercruise.
 
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Inst

Senior Member
Just to clarify, aircraft max speed is a function of a few factors. First, what is the max sustainable speed on the airframe? For instance, the SR-71 and MiG-31 needed specific airframe designs and materials to sustain high speeds without breaking up.

Second, what is the drag of the aircraft? In the MiG-25's case, the aircraft had a very poor T/W ratio, but the low drag of the aircraft allowed it to achieve the rated speeds.

Third, how does the engine/intake combo perform at the given speed? For instance, the F-14 was re-engined over time, but the increased thrust failed to result in higher speeds because the inlets were never modified to provide the higher airflows needed to maintain high thrust at high speeds. What you ended up getting was strong acceleration at lower speeds without an increase in airflow.

The J-20, strictly, needs around 10,000 to 15,000 kgf to go supersonic at altitude, which is only equivalent to 100kn to 150kn of thrust, something AL-31 can do at sea level. But the actual question is, can the AL-31 / WS-10 provide such thrust at speed and altitute? We know that on the Su-27, the AL-31 can't.

So that's why we talk about WS-10C and WS-10D. The engine needs to be designed to have the dry thrust at speed and altitude to take the aircraft supersonic, and maintain sufficient thrust to at least get past 1.3 Mach for it to be a true supercruiser (able to break past supersonic drag spikes as well as have enough dry thrust to exceed the point where normal supersonic drag exceeds that of the Mach 1 spike).
 

pipaster

Junior Member
Registered Member
Article on the certification of the wz-16.

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The Civil Aviation Authority of China (CAAC) has certificated the WZ16 turboshaft that will power the AVIC AC352 7t multi-role helicopter.

The engine is based on the Safran Ardiden 3C that powers the Airbus Helicopters H175, on which the AC352 is based. It was jointly developed by Safran and the Aero Engine Corporation of China (AECC).

The news follows EASA’s certification of the Ardiden 3C in 2018.

Safran says that the WZ16 “is the first jointly-developed aero engine to be entirely certified by Chinese authorities.”

The specific AECC units involved in the work are Harbin Dongan Engine and Hunan Aerospace Propulsion Research Institute.

“Certification from Chinese authorities marks a major milestone for Safran Helicopter Engines and AECC” says Safran executive vice president Bruno Bellanger.

“It confirms that the WZ16 is now ready to operate in accordance with world-class Chinese safety and performance standards, thanks to an intensive maturation plan conducted by our partners. It is also a historic moment for the Chinese aerospace industry as it is the first-ever jointly-developed aero engine to be entirely CAAC certified, and a major step toward AC352 entry-into-service.”

The AC352 conducted its maiden flight in December 2016, and has been undergoing testing since then.

The WZ16/Ardiden 3C turboshaft falls in the 1,700-2,000shp range
 
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