Sukhoi Su-57 / T-50 / PAK FA - flight testing and development Part II [2012-current]

icyplanetnhc (Steve)

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Even maximum thrust figures are rather murky, and as far as I know, no official thrust figures were actually given. Piotr Butowski has repeatedly reported Saturn stating that the izdeliye 30 will be 16-17% “more effective” than the AL-41F1 without specifying what that exactly means. If “more effective” refers to maximum augmented thrust, then it would produce about 166 kN, but again this is simply a static thrust value.

How would you increase mass flow through an engine of the same diameter if you don't improve the compression and thermal characteristics?

BTW I am addressing both exhaust velocity and mass flow, being both the main manageable factors of thrust as you say. It is obvious that improving any of those two is of immediate use in a supercruising engine.
Compare the OPR and airflow for similar weight and size class engines like the F404, RB199, Snecma M88, or EJ200 and you'll see that OPR itself isn't directly correlated to mass flow. It all depends on the specific engine's design points. For an engine with similar dimensions as the AL-31F family, I would expect that the izdeliye 30 may have some increased airflow, but not hugely so. Mass flow itself is not something you specifically design an engine around.
 
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Anduriel

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Even maximum thrust figures are rather murky, and as far as I know, no official thrust figures were actually given. Piotr Butowski has repeatedly reported Saturn stating that the izdeliye 30 will be 16-17% “more effective” than the AL-41F1 without specifying what that exactly means. If “more effective” refers to maximum augmented thrust, then it would produce about 166 kN, but again this is simply a static thrust value.
I get 172 kN(147kN*1.17), which is ~17500kgf and quite close to 18tf thrust mark that is popular in speculation.
 

icyplanetnhc (Steve)

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I get 172 kN(147kN*1.17), which is ~17500kgf and quite close to 18tf thrust mark that is popular in speculation.
As far as I know, the AL-41F1 has a maximum thrust of 14.5 metric tons (142 kN), with a special/emergency setting of 15 tons (147 kN). I don't think the latter is meant to be used normally.
 
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LMFS

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Saturn (Lyulka) have given the temperature figures.
Do you have the source? In any case, how do you explain those temperatures you mention plus a high BPR to produce a higher specific thrust than both F119 and F135?

No dry thrust figures for Izdeliye 30 are available, so conclusions on bypass ratio are purely speculation.
Why would such values be conclusive and statements about specific thrust would not?

Higher temperatures should reduce SFC across the board. If its truly optimised for supercruise, then bypass ratio would be 0.3 or close to it.
And same SFC of AL-31F? VCE starts making sense? Or the engine is technologically so much ahead of the F119? Honest question...

I'd expect it to be lower bypass ratio than AL-31F, which means for the same external physical diameter it has a proportionately larger core, which will help increase dry thrust. Low bypass ratio engines get a smaller thrust boost from afterburning however, so a high afterburning thrust says nothing much about bypass ratio - the best clue to that is the relative thrust of military to afterburning.
Yes, but we do not have that relationship mil to max. The only hint that we have in that regard is the statement about specific thrust, as said above.

There's not enough data points to do more than speculate though.
Not fruitless speculation IMHO, Marchukov has already given away many of the main features of the engine. But we will see.

Even maximum thrust figures are rather murky, and as far as I know, no official thrust figures were actually given. Piotr Butowski has repeatedly reported Saturn stating that the izdeliye 30 will be 16-17% “more effective” than the AL-41F1 without specifying what that exactly means. If “more effective” refers to maximum augmented thrust, then it would produce about 166 kN, but again this is simply a static thrust value.
I have not taken the 18 tf claim seriously until I got wind of a 2012 statement where Marchukov talked about specific weight of the engine being 1/3 lower than izd. 117S. That would be TWR of the engine around 13 and a max thrust of ca. 18 tf, if we assume the weight as 1400 kg (izd. 117 should be 1370 kg). I don't use Butowski's data, they might be right but they are very unspecific and unsourced.

Compare the OPR and airflow for similar weight and size class engines like the F404, RB199, Snecma M88, or EJ200 and you'll see that OPR itself isn't directly correlated to mass flow. It all depends on the specific engine's design points. For an engine with similar dimensions as the AL-31F family, I would expect that the izdeliye 30 may have some increased airflow, but not hugely so. Mass flow itself is not something you specifically design an engine around.
Of course, every engine uses a different set of parameters. But if you jump from one generation to the next, a series of technological parameters like TIT and OPR improve, because they are the direct ways of improving mass flow and exhaust velocity and hence improving thrust. I don't try to be 200% correct and exhaustively so in every single case, but this is a rule of thumb that I think is fully reasonable to use, specially if supported by other evidence.

About the second part, I also don't assume the mass flow in the izd. 30 is hugely bigger than AL-31F (what is huge BTW?), I, as apparently you too, assume they tried to improve in that part too, because it makes sense when you have less stages, better materials, 3D aero design and so on.

As far as I know, the AL-41F1 has a maximum thrust of 14.5 metric tons (142 kN), with a special/emergency setting of 15 tons (147 kN). I don't think the latter is meant to be used normally.
For izd. 117 no official thrust values have been given that I have seen. The best evidence I know are statements from Pogosyan about it producing 2.5 tf of thrust more than AL-31F and weighting 150 kg less. The official values for izd. 117S are known, though, as 14 tf max (normal) / 14.5 tf max (emergency mode).
 

stealthflanker

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On the thrust figure of AL-41F1 (117) and Izd-30. This is from Saturn presentation. Scaling from that graph it's where the 17500 Kgf figure come from. Which i think reasonable.

The one with 14500 Kgf is as seen the 117S (AL-41F1S).
 

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Avimimus

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There have been mentions of a potential five missile A2A internal readout on LTS. This makes me wonder if the update the su57 is supposedly going to get in a few years might also include an eight missile internal loadout.

We've generally assumed two 700kg rated hardpoints per bay... (as the bays are designed around such weapons). However, some people always claimed there was enough volume for three 400kg hardpoints.

The real question is whether it is possible to have a 2x700kg hardpoints, and a 400kg hardpoint in the middle - and have them all positioned in such a way that the 700kg hardpoints can carry either a high diameter in the middle of each side of the bay or a narrower missiles while leaving enough room for a third missile in the middle (or whether it is possible to have 2x700kg hardpoints and 3x400kg hardpoints in the same bay (and just use the hardpoints which are appropriate to a given loadout)!
 

icyplanetnhc (Steve)

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The AL-41F1 (izdeliye 117) is not very different from the AL-41F1S (izdeliye 117S), with the biggest distinction being the latter’s own control unit, while the 117 is integrated into the Su-57’s flight control system. I would expect them to weigh nearly the same at roughly 1,600 kg. The Izdeliye 30 should weigh less, as it has fewer fan and compressor stages and more modern materials. I believe the target weight is about 1,450 kg.
 

overscan (PaulMM)

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The AL-41F1 (izdeliye 117) is not very different from the AL-41F1S (izdeliye 117S), with the biggest distinction being the latter’s own control unit, while the 117 is integrated into the Su-57’s flight control system. I would expect them to weigh nearly the same at roughly 1,600 kg. The Izdeliye 30 should weigh less, as it has fewer fan and compressor stages and more modern materials. I believe the target weight is about 1,450 kg.
Unless the control unit weighed 150kg I suppose?
 

haavarla

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The AL-41F1 (izdeliye 117) is not very different from the AL-41F1S (izdeliye 117S), with the biggest distinction being the latter’s own control unit, while the 117 is integrated into the Su-57’s flight control system. I would expect them to weigh nearly the same at roughly 1,600 kg. The Izdeliye 30 should weigh less, as it has fewer fan and compressor stages and more modern materials. I believe the target weight is about 1,450 kg.
Unless the control unit weighed 150kg I suppose?
Doubt it. I read somewhere they used different alloys on some of the 117 stages. Hense less weight.
 

LMFS

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Pogosyan said it weights 150 kg less than the AL-31F, not the AL-41F-1S. We can chose to take our opinion before his word if we want, of course...
 

overscan (PaulMM)

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AL-31FP weighs 1520-1530kg. AL-41F1S weighs about 1604kg. Brochure figures. We have no definitive weight for 117, only a single comment from 2010 aimed specifically at rebutting Russian media criticisms of the engine choice. Sukhoi also claimed 30% lower weight for Izdeliye 30 - which is 1071kg, which is lighter than F414. We'll see about that I guess.
 

LMFS

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AL-31FP weighs 1520-1530kg. AL-41F1S weighs about 1604kg. Brochure figures. We have no definitive weight for 117, only a single comment from 2010 aimed specifically at rebutting Russian media criticisms of the engine choice. Sukhoi also claimed 30% lower weight for Izdeliye 30 - which is 1071kg, which is lighter than F414. We'll see about that I guess.
The comment is a technical statement and comes from a top respected and knowledgeable guy, UAC head at the time IIRC, so I am more than ready to basically take it at face value, at least when it makes sense and we have no other valid source that contradicts it. That would be 1370 kg for the izd. 117.

As to the 30% lower weight of the izd. 30, it was actually specific weight, which is the inverse of thrust to weight ratio. And that value, for a weight of ca. 1400 kg, gives the famously claimed thrust of 18 tf.
 

icyplanetnhc (Steve)

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Roughly 1,600 kg mass for the AL-41F1 was given in multiple publications by Butowski, who has thus far proven to be very accurate with regards to the Russian aerospace industry.

If we are to take the “official” figures at face value, then the numbers would be preposterous. If specific weight refers to the inverse of thrust-to-weight ratio, then 30% lower specific weight means 43% greater T/W. If the AL-41F1 (117) really does weight 1,370 kg with 14.5 tons of thrust, then the izdeliye 30 will have a T/W of 15.1, and (assuming ~1,400 kg mass) have a thrust of 21.2 tons (208 kN, 46,600 lbf)

Sorry, but nope…
 
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LMFS

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1,600 kg for the AL-41F1 was given in multiple publications by Butowski, who had thus far proven to be very accurate regarding the Russian aerospace industry.

If we are to take the official figures at face value, then the numbers would be preposterous. If specific weight refers to the inverse of thrust-to-weight ratio, then 30% lower specific weight means 43% greater T/W. If the AL-41F1 really does weight 1,370 kg with 14.5 tons of thrust, then the izdeliye 30 will have a T/W of 15.1, and a thrust of 21.1 tons.

Sorry, but no…
Butowski seems very well connected, but he has made such outlandish claims as Okhotnik having the same low altitude max speed as a Su-35. My personal choice is to take a top UAC official anytime, specially when they are actual technical people knowing what they talk about, but who knows.

As to the 30% lower specific weight, it was referred to the izd. 117S, whose official weight is the one overscan noted above, 1604 kg. So TWR of izd. 30 is 12.9, corresponding to ca. 18 tf if we assume 1400 kg weight. May be more, may be less, but it is reasonable.
 
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Bhurki

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Having gone through multiple sources that cite info about the new engines in the last week, I find that the language deviates quite a bit on both sides of the mean reference(117s). Though, one strand of info seems to resonate through all, 'the thrust capability vis-a-vis the weight (specific weight) will be about 30% higher'.
I'm not adept at understanding the nuances of the Russian language, but they are probably referring to the T/W ratio.

1.3x 9.3 is 12.0.
It would be safe to assume that the final product will deviate on standard around this number. Whether it be 19 tons at 1600 kg, 17 tons at 1400 kg or anywhere in the middle.
 
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LMFS

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Having gone through multiple sources that cite info about the new engines in the last week, I find that the language deviates quite a bit on both sides of the mean reference(117s). Though, one strand of info seems to resonate through all, 'the thrust capability vis-a-vis the weight (specific weight) will be about 30% higher'.
I'm not adept at understanding the nuances of the Russian language, but they are probably referring to the T/W ratio.
Could you refer the sources?

1.3x 9.3 is 12.0.
I don't understand this.
- It is the inverse of TWR that is ca. 30% lower in izd. 30 than in 117S.
- That value is calculated based on max thrust, not mil.
- Mil value for 117S is 8.8 tf
 

icyplanetnhc (Steve)

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Butowski seems very well connected, but he has made such outlandish claims as Okhotnik having the same low altitude max speed as a Su-35.
Where? He did initially put the S-70’s maximum speed as 1,400 km/h, but it has since been written as 1,000 km/h in more recent publications, including his 2021 book on the Su-57.

As far as specific weight or T/W, and what the baseline for the comparisons is, I’ve perused through several sources but often times, the specifics are often appended by the journalist rather that directly from officials themselves. Again, there are nuances to the Russian languages that can result in quite significantly different quantitative results. Is it “specific weight” that’s 30% better, or T/W? I have yet to find a statement directly from Lyulka-Saturn that establishes the specific weight improvement and the baseline that it’s being compared to, based on the sources that I have read. Perhaps you can provide one?
 

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I don't understand this.
- It is the inverse of TWR that is ca. 30% lower in izd. 30 than in 117S.
Specific thrust or thrust at specific weight means thrust per unit mass.
Unless “specific thrust” means thrust per unit of airflow - not thrust to weight.

Supercruise requires high exhaust velocity at Mil power at supersonic inlet conditions. Typically this requires low bypass ratio, which implies a large core (high compressor, combustor, high turbine). Big cores are heavy and low bypass reduces augmentation ratio, making 12:1 T/W very unlikely for a supercruise engine that has any measure of durability.
 

Bhurki

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making 12:1 T/W very unlikely for a supercruise engine that has any measure of durability
We're trying to assess the max T/W limit here. Anything lower is viable.
This is for the people who are suggesting that somehow a 1200 kg engine could produce 20 tons of thrust.
 

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Where? He did initially put the S-70’s maximum speed as 1,400 km/h, but it has since been written as 1,000 km/h in more recent publications, including his 2021 book on the Su-57.
Proves he has a questionable technical knowledge.

As far as specific weight or T/W, and what the baseline for the comparisons is, I’ve perused through several sources but often times, the specifics are often appended by the journalist rather that directly from officials themselves. Again, there are nuances to the Russian languages that can result in quite significantly different quantitative results. Is it “specific weight” that’s 30% better, or T/W? I have yet to find a statement directly from Lyulka-Saturn that establishes the specific weight improvement and the baseline that it’s being compared to, based on the sources that I have read. Perhaps you can provide one?
Specific weight is what Russian industry uses. This is one of the sources that reported such statements:

NPO Saturn creates a 5+ generation engine

Bench tests of a fundamentally new engine (engine of the second stage) for the Russian fifth-generation aircraft PAK FA will begin in 2014, said Evgeny Marchukov, General Designer-Director of the Lyulka Scientific and Technical Center of NPO Saturn.

“The engine will be ready in hardware in two years, and bench tests will begin, and its refinement will take place,” said E. Marchukov at the 11th International Conference “Aviation and Cosmonautics - 2012”, which opened at the Moscow Aviation Institute on Tuesday.

According to him, the new "engine 117" will belong to the "5+" generation and will surpass the existing foreign counterparts of engines for fifth-generation aircraft in terms of its characteristics.

“This is a fundamentally new engine, so it takes a long time to create. The engine has a 30% less specific gravity (than 117C - approx.), The life cycle cost is also 30% less, and it itself should be cheaper, "- said E. Marchukov.

Specific thrust or thrust at specific weight means thrust per unit mass.
See comment from F119Doctor

Marchukov reported recently that the specific thrust of izd. 30 was the highest of any comparable engine, worldwide. All indicates they use that term in the same sense than the West

Supercruise requires high exhaust velocity at Mil power at supersonic inlet conditions. Typically this requires low bypass ratio, which implies a large core (high compressor, combustor, high turbine). Big cores are heavy and low bypass reduces augmentation ratio, making 12:1 T/W very unlikely for a supercruise engine that has any measure of durability.
Izd. 30 has a lower stage count, but I cannot comment on whether that T/W is realistic or not. Maybe it being VCE would do the trick and allow to raise AB thrust enough? It may be more complex and heavy due to the variable circuit on the one hand, but augmentation could be more effective too.
 

icyplanetnhc (Steve)

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Proves he has a questionable technical knowledge.

Butowski has overwhelmingly demonstrated himself to be correct more often than not. Pointing to isolate instances of errors that he has since corrected as "proof" of questionable technical knowledge and dismissing his work is frankly preposterous. I would rate his assessments very highly, especially if they have remained consistent over time.

The verbatim statement was "specific gravity" when translated from Russian to English. This is a different property from specific weight, and I haven't heard of this term used to describe engine performance characteristics (I’ve only heard of it used for fuel density). I would prefer to have someone who understands the nuances of the Russian language to clarify what this refers to.

EDIT: Calling him questionable? He published the turbomachinery architecture of the izdeliye 30 (3 stage LPC/fan, 5 stage HPC, 1 stage HPT, 1 stage LPT) as early as 2013. He drew the N036 side arrays quite accurately before the aircraft even first flew.
 
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LMFS

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Butowski has overwhelmingly demonstrated himself to be correct more often than not. Pointing to isolate instances of errors that he has since corrected as "proof" of questionable technical knowledge and dismissing his work is frankly preposterous. I would rate his assessments very highly, especially if they have remained consistent over time.
That is why I said he is very well connected, I take his reports seriously too. But what I find preposterous is to think he is on a higher level as a source than the head of UAC...
The verbatim statement was "specific gravity" when translated from Russian to English. This is a different property from specific weight, and I haven't heard of this term used to describe engine performance characteristics. I would prefer to have someone who understands the nuances of the Russian language to clarify what this refers to.
Russians don't use the same terminology than us, but of course, go ahead and do your research please.
 

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izd. 117S (Su-35S) 14500 kgf / 8870 kgf, short-term mode-15000 kgf, engine weight 1604 kg-dry weight of the engine in a "simple configuration"
izd 117 (Su-57) 15500-16000 kgf / 9800 kgf
izd 30 (Su-57) 17500 kgf / 11000 kgf engine weight 1750 kg
 

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izd. 117S (Su-35S) 14500 kgf / 8870 kgf, short-term mode-15000 kgf, engine weight 1604 kg-dry weight of the engine in a "simple configuration"
izd 117 (Su-57) 15500-16000 kgf / 9800 kgf
izd 30 (Su-57) 17500 kgf / 11000 kgf engine weight 1750 kg
Rosobornexport official data (izd. 117S)

Special power conditions, kgf 14500-2%
Full afterburner military thrust, kgf 14000-2%
Max military thrust (w/o afterburning), kgf 8800±2%

http://roe.ru/eng/catalog/aerospace-systems/engines/al-41f-1s/

For the rest of the data, we need a source or reasoning to start with...
 

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Deputy Chief Designer A. S. Bulatov:
- the engine of the fighter "75", existing, in the thrust class of 14.5-16 tons (end of quote)

Obviously izd. 117C and izd. 117
 
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Scar

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As far as i can understand, again, from Bulatov' speech, this will be a new version of izd.117.
 

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Bulatov speaks at the mark 17:45 about the engine

View: https://www.youtube.com/watch?v=Vy4Q-NoQyoo


As per the transcription here:

Bulatov said that "the engine will be in the 14.5-16 t class. This engine is made on the basis of the groundwork of the United Engine Corporation, and will be even more advanced on this aircraft."

It does seem to indicate that there will be a further development of the 117 for this plane, at least for the export version. Which makes sense, since thrust is one of the main apparent constraints for such concept.
 

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I am going to quote here for reference some excerpts about the izd. 30 from the last interview with Marchukov at N+1 a couple of years ago:


“The difference between engines of different generations is manifested, first of all, in their specific parameters. There are several main parameters: specific gravity, specific thrust and specific fuel consumption per kilogram of thrust per hour. The generational change occurs with the simultaneous improvement of all these characteristics. In this regard, “Product 30” can even be attributed to the “5+” generation, since this engine was created taking into account domestic and foreign experience in the development and operation of fifth-generation engines. In the USSR, and then in Russia, this engine was “Product 20”. It was planned to install it on the MiG-1.44 MFI fighter being developed by the MiG corporation. Then “Product 30” appeared, ”said N + 1 Marchukov.

>> Izd. 30 should be expected to go beyond parameters of known 5G engines.
>> The reference of izd. 30 as a follower of izd. 20 is very obvious here

Specific gravity in aviation is usually called the ratio of the mass of the engine to its total thrust. For the promising "Product 30" this figure is less than 0.1, that is, the engine is capable of delivering more than 10 times more thrust than it weighs itself. Specific thrust is the ratio of the total thrust to the air flow rate of the engine.

>> About the questions above on the meaning of specific weight/gravity parameter.
>> The above estimation of 17500 kgf / 1750 kg weight is explicitly denied here. The ratio 10:1 was already surpassed at izd. 117 (ca. 11:1)

In the second stage engine for the Su-57, the developers applied a number of new design approaches and technologies, due to which the "Product 30" in terms of specific fuel consumption roughly corresponds to the AL-31F bypass engine (670 grams per kilogram-force per hour in cruising mode), but surpasses its in terms of specific thrust.

>> Unclear, whether this is just the journo saying it. But the wording seems solid and well documented. It is complemented in any case by the subsequent statement quoted to Marchukov:

“Specific fuel consumption opposes specific thrust. The best fuel consumption is obtained on civilian by-pass engines, but they have the least specific thrust due to the high by-pass ratio. In single-circuit engines, on the contrary, the specific thrust is high, but the consumption is also high. Due to the use of new designs and technologies in "Product 30" the specific consumption remained at the same level, but the specific thrust increased, "Marchukov said.

>> The hint to VCE is not so subtle here, me thinks.

“Compared to engines of the fourth generation, the fifth has added the ability to cruise supersonic motion - for this, the engine must have a variable bypass ratio. This requirement added one more specific parameter - specific fuel consumption at cruising supersonic. Also, the engine should have significantly less visibility in the infrared and radio wavelengths. This is achieved by a special design of the nozzle and air intake. A serious aspect of the new engine is also a reduction in the cost of the machine's life cycle - less maintenance costs, more overhaul life, ”Marchukov said about the new power plants.

>> I am at a loss to explain how VCE remains a taboo word after the designer has said the above... 5G engine needs to be VCE, and izd. 30 is in fact 5.5G... someone wants to join the dots for me here?
 
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icyplanetnhc (Steve)

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I am at a loss to explain how VCE remains a taboo word after the designer has said the above... 5G engine needs to be VCE, and izd. 30 is in fact 5.5G... someone wants to join the dots for me here?
This very interview has already been discussed here more than 2 years ago. I have even inquired about it, but actual Russian speakers have said that variable cycle refers to future developments, not the izdeliye 30 itself.

https://www.secretprojects.co.uk/th...opment-part-ii-2012-current.15626/post-347148
 

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Specific gravity would more refer to the volumic mass (that's what it is generally). Here, as taken as a design parameter it would refer to the property of the total mass of the engine divided by its volume and give an indication of how components and accessories design have evolved.

It is not the Thrust to Weight ratio that is the next parameter mentioned in the interview as quoted above by @LMFS
 

overscan (PaulMM)

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“The difference between engines of different generations is manifested, first of all, in their specific parameters. There are several main parameters: specific gravity, specific thrust and specific fuel consumption per kilogram of thrust per hour. The generational change occurs with the simultaneous improvement of all these characteristics. In this regard, “Product 30” can even be attributed to the “5+” generation, since this engine was created taking into account domestic and foreign experience in the development and operation of fifth-generation engines. In the USSR, and then in Russia, this engine was “Product 20”. It was planned to install it on the MiG-1.44 MFI fighter being developed by the MiG corporation. Then “Product 30” appeared, ”said N + 1 Marchukov.

specific gravity is the ratio of density of a substance compared to an equal volume of water, typically.


It is common to use the density of water at 4 C as a reference since water at this point has its highest density of 1000 kg/m3

Unless Russian usage of this term is different and is specific weight i.e. weight/thrust. If the figure of "better than 0.1" is correct for weight/thrust then it means t/w ratio is above 10, but nothing in this interview says 12:1.

Specific thrust which is mentioned next though is thrust to mass flow rate NOT thrust to weight and again is more of an indicative design parameter, this relates to supercruise optimisation. High specific thrust means its acting like a turbojet, giving more thrust for a given flow rate. This would normally come at a cost in specific fuel consumption, which Saturn mention effectively remains the same as AL-41F1.

“Specific fuel consumption opposes specific thrust. The best fuel consumption is obtained on civilian by-pass engines, but they have the least specific thrust due to the high by-pass ratio. In single-circuit engines, on the contrary, the specific thrust is high, but the consumption is also high. Due to the use of new designs and technologies in "Product 30" the specific consumption remained at the same level, but the specific thrust increased, "Marchukov said.

This directly suggests mass flow rate is probably not increased over AL-41F1, the thrust increase being attributable to improved engine cycle with greatly increased temperatures.

The interview says that AL-41F1S replaced 70% of AL-31F parts, and AL-41F1 replaced 80%. This suggests they are pretty similar, and its hard to think AL-41F1 is 150kg lighter from replacing 10% of parts unless they were very heavy parts.
 
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overscan (PaulMM)

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“Compared to engines of the fourth generation, the fifth has added the ability to cruise supersonic motion - for this, the engine must have a variable bypass ratio. This requirement added one more specific parameter - specific fuel consumption at cruising supersonic. Also, the engine should have significantly less visibility in the infrared and radio wavelengths. This is achieved by a special design of the nozzle and air intake. A serious aspect of the new engine is also a reduction in the cost of the machine's life cycle - less maintenance costs, more overhaul life, ”Marchukov said about the new power plants.

>> I am at a loss to explain how VCE remains a taboo word after the designer has said the above... 5G engine needs to be VCE, and izd. 30 is in fact 5.5G... someone wants to join the dots for me here?
Pratt & Whitney's F119-PW-100 is the foundational fifth generation engine and is not variable cycle as he well knows, so something doesn't add up. He definitely talks about VCE for the next generation after Izdeliye 30 later in the interview. Nothing conclusive in my opinion. He may be talking about the fifth generation as Izdeliye 20 which did have VCE.
 

LMFS

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This very interview has already been discussed here more than 2 years ago. I have even inquired about it, but actual Russian speakers have said that variable cycle refers to future developments, not the izdeliye 30 itself.
Yes, I know it was discussed, that is why I did not quote it until fundamental questions appeared that called for the clarifications contained in it.

What is clear is that the 3 stream design is a development for the future, for what is called in Russia the 6G engine, see below. Russian speakers can help in determining if the translation above is correct, for the rest we have our own brains I guess...

UEC_2018_002_EN.png

@TomcatViP @overscan (PaulMM)

Specific gravity is defined in the article, a value consistent with T/W provided, and Marchukov also said it would be smaller in the izd. 30 than in izd. 117S. Given their sizes are equal, that would mean 1000 kg for the izd. 30, which does not make any sense. In general, density is not a technological parameter of engines and seems irrelevant to define a generation based on it. Besides:

The article:
Основных параметров несколько: это удельный вес, удельная тяга и удельный расход топлива на килограмм тяги в час.

weight
  • вес,
  • масса,
  • груз,
  • тяжесть,
  • нагрузка,
  • значение

Should be clear now.

Specific thrust which is mentioned next though is thrust to mass flow rate NOT thrust to weight and again is more of an indicative design parameter, this relates to supercruise optimisation. High specific thrust means its acting like a turbojet, giving more thrust for a given flow rate. This would normally come at a cost in specific fuel consumption, which Saturn mention effectively remains the same as AL-41F1.
Yes, this is what we said and explained in the text. The name of the parameter and its interpretation is analogue to the Western one.

This directly suggests mass flow rate is probably not increased over AL-41F1, the thrust increase being attributable to improved engine cycle with greatly increased temperatures.
SFC is a thrust specific value, it says nothing about mass flow. It is logical to expect improved design of the compressor, apart from increased temperature.

The interview says that AL-41F1S replaced 70% of AL-31F parts, and AL-41F1 replaced 80%. This suggests they are pretty similar, and its hard to think AL-41F1 is 150kg lighter from replacing 10% of parts unless they were very heavy parts.
150 kg is a 10% of the weight of the AL-31F, I don't think it is crazy to think that you can gain that with 80% of the pieces being different. Nobody says the new pieces in 117S and 117 are the same, BTW, though it may seem logical to think so.

Pratt & Whitney's F119-PW-100 is the foundational fifth generation engine and is not variable cycle as he well knows, so something doesn't add up. He definitely talks about VCE for the next generation after Izdeliye 30 later in the interview. Nothing conclusive in my opinion. He may be talking about the fifth generation as Izdeliye 20 which did have VCE.
Or about YF120, since for both sides it has always been clear that the proper solution for a supercruising plane is a VCE, because otherwise the specific thrust demands of the supersonic flight regime force the engine to be inefficient in all other conditions. This is the way I interpret that statement, as a how things are from a theoretical point of view, despite of USAF having opted for the F119. At that time they were under no pressure from rivals and taking the lower risk option was a logical thing to do. They should have not relaxed that much though, Russia did not forget the lessons from izd. 20 and they may use the window of opportunity that US created for them. A 2 stream VCE may not be as advanced as the adaptive engine US is working full speed on, but it is better than having fixed BPR.

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overscan said:
Unless Russian usage of this term is different and is specific weight i.e. weight/thrust. If the figure of "better than 0.1" is correct for weight/thrust then it means t/w ratio is above 10, but nothing in this interview says 12:1.
The statement about specific weight compared to 117S was linked some posts above, as per my calculation TWR would be ca 13:1. F135 is estimated at 12:1 from what I know, so this would be a bit better, but not something out of this world.
 
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overscan (PaulMM)

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@LMFS Specific gravity can't be "defined in the article" it is a standard engineering parameter. You can't just redefine it to mean something different, and the explanation of specific gravity in the article is presumably by the journalist. Either the wrong word was used or the meaning ascribed by the journalist was incorrect.

Also you seem to being deliberately obtuse in regard to your mass flow argument. The article specifically says specific thrust is increased. This means more thrust per unit of mass flow. If thrust of Izdeliye 30 is say 17500kg compared to 15000kg for Ideliye 117, thats 16.67 % increase in thrust. By the terms of this article, if the mass flow of Izeliye 30 is higher, then that reduces the increase in specific thrust. Its possible that mass flow is slightly higher (say, 5%), but if mass flow of Izdeliye 30 was 20% higher, for 17% more thrust, then specific thrust would be LOWER than Izd. 117. This is basic maths not advanced engineering.

This discussion belongs in the Propulsion forum and I will move the posts there eventually.
 
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@LMFS Specific gravity can't be "defined in the article" it is a standard engineering parameter. You can't just redefine it to mean something different, and the explanation of specific gravity in the article is presumably by the journalist. Either the wrong word was used or the meaning ascribed by the journalist was incorrect.
удельный вес means specific weight, the machine translation used the word gravity instead of weight, and the article provided the explanation about what they are referring too, even if you don't want to check the translation for accuracy. You are also ignoring the rest of the evidence I provided. The density of an engine is not a meaningful parameter and cannot be 0.1, unless you are willing to accept it weights 180 kg by your proposed definition...

Also you seem to being deliberately obtuse in regard to your mass flow argument. The article specifically says specific thrust is increased. This means more thrust per unit of mass flow. If thrust of Izdeliye 30 is say 17500kg compared to 15000kg for Ideliye 117, thats 16.67 % increase in thrust. By the terms of this article, if the mass flow if Izeliyie 30 is higher, then that reduces the increase in specific thrust. Its possible that mass flow is slightly higher (say, 5%), but if mass flow of Izdeliyie was 20% higher, for 17% more thrust, then specific thrust would be LOWER than Izd. 117. This is basic maths not advanced engineering.
I am not being obtuse, believe me. You are taking specific thrust, which refers to mil settings of which we have no values for the izd. 30, and mixing it with max thrust where such consideration does not apply, because the AB is in operation, burning all the oxygen that bypassed the core.

To get an increase in mil thrust both mass flow and specific thrust can and are normally increased, check for instance the different versions of the AL-31F in this regard.
Additionally, if f we talk about a VCE, then the situation is even more complicated, because there can be a setting with low BPR for highest mil / specific thrust and another for highest settings in AB.

As to the corresponding thread, yes please move the posts where you see them fit.
 
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