Su-57 intakes, supercruise performance and 2nd stage engine

[chuck4]

I've yet to see any indications that the T-50 will have 3D TV ....

I also don't see evidence of any new technology engines in the same thrust or technology class of supercrusiging PW F-119 / GE F-120 engine of the F-22 in the relatively near future for the T-50. The development of Soviet equivalent to GE F-120 engine - the original AF-41 - was terminated in the 1990s. Appearently AF-41 still required more development than could have been supported by Russian airforce funding or by projected foreign sales. So it was nowhere near close to being ready.

Since that time, the Russians have upgraded Su-27's class AF-31 engine time and again. The latest upgrade to A-31 recycled the model designation AF-41, but isn't really related to the original AF-41. It's still just a further refinement of the AF-31, still using the original AF-31 hot core. AF-31 can only be developed so far. Based on the fact that latest AF-31 derivative is already over 30% more powerful than the base model used in Su-27, I will guess it is reaching the limits of its development potential. But the latest, evolved model AF-31 is still a good 25% less powerful than the base model PW F-119.

So this suggests to me unless T-50 turns out to be much lighter than F-22, despite being larger in every dimension, it won't be able to match F-22's thrust to weight ration any time soon. So if T-50 is as heavy as F-22, as its dimensions suggests, then it would probably be constrained in acceleration, climb, and sustained turning performance compared to F-22. But if it is lighter than F-22, then it would probably be constrained in fuel and weapon load compare to F-22 and enjoy nowhere near the awesome range and combat persistence sometimes credited to it.

This also applies to the Chinese J-20, which also uses a derivative of the AF-31 engine.

 

[Wil]

But the latest, evolved model AF-31 is still a good 25% less powerful than the base model PW F-119.

Is it a joke?
;D ;D

 

[chuck4]

But the latest, evolved model AF-31 is still a good 25% less powerful than the base model PW F-119.

Is it a joke?
;D ;D

No. The latest AF-31 derivative is the AF-41F1 (117). The director of Sukhoi claims this is the intended engine for PAK-FA. 117's is rated around 14500 kgf with AB. The F-119 is classified but likely in the 18000 kgf range with AB. The F135 derivative is >20000 kgf

With 117 engine, T-50 needs to have a combat weight at least 6-7 tons lighter than F-22 in order to match F-22's current t/w ratio. If T-50 turns out to be of similar weight as the F-22, then with 117 engine its thrust to weight ratio with AF would be in the uninspiring F-4 phantom territory.

And T-50 is bigger than F-22 in every dimension, and some claim it also carry a much larger internal fuel load then the F-22. I suspect it won't be 6-7 tons lighter than F-22.

Unless the Russians resurrect the original AF-41 program for the Mig 1.44, not the current jumped up AF-31 that's been restyled as "AF-41F1" , I don't see a F-119 class engine in T-50's foreseeable future.

So I am guessing T-50 won't be fully competitive against the F-22 in every part of its envelope in every measure of maneuverability and agility.

 

[kaiserbill]

But the latest, evolved model AF-31 is still a good 25% less powerful than the base model PW F-119.

Is it a joke?
;D ;D

No. The latest AF-31 derivative is the AF-41F1 (117). The director of Sukhoi claims this is the intended engine for PAK-FA. 117's is rated around 14500 - 14700 kgf with AB. The F-119 is classified but likely in the 18000 kgf range with AB. The F135 derivative is >20000 kgf

With 117 engine, T-50 needs to have a combat weight at least 6-7 tons lighter than F-22 in order to match F-22's current t/w ratio. If T-50 turns out to be of similar weight as the F-22, then with 117 engine its thrust to weight ratio with AF would be in the uninspiring F-4 phantom territory.

And T-50 is bigger than F-22 in every dimension, and some claim it also carry a much larger internal fuel load then the F-22. I suspect it won't be 6-7 tons lighter than F-22.

Unless the Russians resurrect the original AF-41 program for the Mig 1.44, not the current jumped up AF-31 that's been restyled as "AF-41F1" , I don't see a F-119 class engine in T-50's foreseeable future.

So I am guessing T-50 won't be fully competitive against the F-22 in every part of its envelope in every measure of maneuverability and agility.

Chuck4, your maths is not adding up.

 

[chuck4]

Difference in thrust between F119 and AF-41F1A: (18000-14500)/14500 = 24.1% So F119 is 24.1% more powerful than the version of AF-41F1A used in T-50.

Total difference in total thrust of two engines (18000-14500)*2 =7000kgf. So if F-22 has thrust to weight ratio of 1.2, T-50 would need to be 7000/1.2 = 5833 kg lighter to achieve the same thrust to weight ratio.

 

[kaiserbill]

Why are you quoting the performance figures for the AL-41F1A (117S) ???
That engine is not fitted to the PAK-FA.

One of the few parameters made public on the AL-41F1 (117) that is fitted to the PAK-FA prototypes from the very first flight is a thrust of 33000lb, or in the region of 15 000kg.
It is a different engine, with a 10% weight reduction, and will have further stretch in it.
There are already hints of a further development to increase that thrust.
I grant you however, that the Russians can come up with some weird and utterley confusing designations.

 

[chuck4]

Take 14900 kgf for 117, and you still get F-119 being 20.8% more powerful. Russians claims of engine weight reduction of 150kg, presumably compared to some version of AF-31, only goes 5% of the way towards making up for the shortfall in thrust through aircraft weight reduction to achieve parity with F-22 inthe overall aircraft thrust to weight ratio.

But let's focus on just the thrust to weight ratio of the engine. If Russian claims of thrust and weight savings are to be believed, then the 117 already show thrust to engine weight ratio of better than 10:1. This is AFAIK is already better than has ever been achieved by any other after burning turbofan engine. F-119 only achieved around 8:1. So I have to take the claim that Saturn achieved 10:1 in a reliable production engine with several grains of salt, since I would generally credit western manufacturers with the edge in material and fabrication technology. I would also take with salt the claim that Saturn can do better still in the near future.

 

[kaiserbill]

Take 14900 kgf for 117, and you still get F-119 being 20.8% more powerful.

If Russian claims of thrust and weight savings are to be believed, then the 117 already show thrust to engine weight ratio of better than 10:1. This is AFAIK is already better than has ever been achieved by any other after burning turbofan engine. I have to take this with several grains of salt, since I would credit western manufacturers with the edge in material and fabrication technology. I would also take with salt the claim that Saturn can do better still.

Now that we have the right engine at least...

First it was 14500kg, now 14900kg...
It has been stated that the engine develops closer to 15 000kg than 14900kg.
Taking the 18 000kg figure for "the baseline" F-119, this is not a quarter less thrust as you stated. It's closer to a sixth less, which is much more respectable.
It has been stated that there is growth in this engine, which is substantially different from the AL-31.

A couple of other things that affected your math calculations were the creeping of figures.
You stated that the PAK-FA had to be lighter than the F-22 by as much as 7 tons.
Then, even on the incorrect engines on a lower thrust, this becomes 5,8 tons.
Whats the most recent calculation with the correct thrust?
I'm also not so sure of your statement about the "T-50 being bigger than the F-22 in every dimension".
Maybe in length or wingspan, but those are not the only dimensions one has to consider.

The above is basically why I thought your initial maths was flawed.

I agree with you that the original AL-41 was perhaps the way to go, but we are not privy to what went on behind the scenes.
It did get airborne in a Mig-25, but there may be reasons why this path was chosen.
The designer has stated that the new engine is vastly different from the AL-31, and is to all intents and purposes, a "new" engine, as he put it.

There have been plenty of instances before where a new design was given the same designation as a previous one, for funding purposes.
The Tupolev Tu-22 springs readily to mind.

EDIT: I see your edit about the F-119 engine twr.
You are using the thrust of 18000kg for the F-119 for your argument, but using the thrust to weight ratio of 8:1 for the F-119 based on the official thrust of that engine of 35 000lb, or 15 880kg.

You can't have it both ways, and is the primary reason why your maths is flawed.

 

[TaiidanTomcat]

This airplane will only be as good as its engines in terms of kinematic performance. Its that simple. The F119 was flying all the way back with the YF-22 prototype in 1990. Russia's equivilant engine isn't do for another 10 years for the PAKFA. Thats a 30 year gap between the two rival engines.

It makes a huge difference. Math Aside I agree with Chuck4, and have been for about the last 3 pages.

 

[overscan (PaulMM)]

Given the existence of the AL-31F, which has happily been producing 12,500kg thrust for the last 30 years, it is not technically difficult to get advanced derivatives up to 15,000kg (20% thrust increase). Much above that would probably need a substantially new engine.

Noting that the F-15's "25,000lb thrust class engines" turned out to be a bit under 24,000lb thrust, I am not convinced the F-22's "35,000lb thrust class" engines are actually nearly 40,000lbs (18,000kg). That was the thrust target for the original AL-41F.

Its disengenuous to say NPO Saturn are 30 years behind on this. They designed an equivalent engine 20 years ago, which didn't get put into production. They still ran it on bench tests, flew it in a MiG-25, etc. AL-41F (original) was also flown twice (very gingerly) in the MiG 1.44 in 2000. The main issues with it at the time were size (larger diameter than AL-31 meant no good for re-engining existing Sukhois, which was the only work in the 90s) complexity (variable cycle) and reliability (lack of appropriate materials) and most of all insufficient money.

With the Powerjets SaM 146, NPO Saturn have got access to various Western engine technologies. Combined with their own technical resource, they can certainly come up with something roughly equivalent to the F119, which is now pretty old in conception and was less technically ambitious than the AL-41F. No criticism intended to P&W - they were too ambitious on F100 and paid the price on that design for several years, and they bet with ATF that the USAF would go for the less risky design - and won.

 

[Sundog]

The reason for the larger diameter is probably for the same reason the F-119 has a larger diameter than the engines before it; To get the mass flow up through the engines. That's critical for supercruise. Also, I've never doubted the Russians ability to make a great engine. Where they've always had problems is in engine life. Also, although the original YF-119 flew decades ago, the engine in the production Raptor isn't the same. Just as the Russians haven't been sitting still for the past twenty to thirty years in engine development, neither has the U.S.

However, comparing the maximum S/L static thrust of the two engines doesn't really matter, as what's more important is the installed thrust and what it delivers at altitude and the T/W ratio of the engine itself. In fact, that last metric is more important when comparing engines than the thrust they generate. Also, as Paul said, I doubt either country is about to release their engine decks for us to analyze, though I would greatly appreciate it.

 

[kcran567]

The fan face on the T-50 appears to be very close to the engine inlet (unless the pictures are photo shopped to prevent a good view)...


Unless Sukhoi has some sort of advanced blocker that doesn't affect flow 1-5%, and are using plasma to cover the inlets, they are going to lose thrust there. -1


Unless the T-50 settles on a conventional nozzle like the F-35, they are going to pay a weight penalty there. -1


If the estimates are right, the T-50 is at least as large as the F-22, perhaps slightly larger. +1


Unless the T-50 is made out of advanced tin foil, it has to either carry less fuel than the F-22, or be made of even more advanced and lighter materials than the F-22 to come in at a comparable weight. -1


Considering these factors, the T-50 has to have either a higher thrust engine available or suffer from lower fuel volume to save weight. I don't believe Sukhoi is going to sacrifice thrust if possible, but if they do either range or performance is going to be less than the F-22. -1


That's 4 to 1 in favor of the F-22 so far...


One last thing about T-50 agility:


Re: the new flight suit, If the T-50 is going to be able to do flat turns in yaw a 6-7g, then I'll say it is groundbreaking in agility, but with those small vertical tails, even with the TVC, I doubt it will be much more agile in yaw. We'll see. But 3-4g in yaw might be realistic, but again, is that ballistic or controllable. If its ballistic inertia its not going to be that precisely controlled.

 

[lancer21]

I think that's the high-rez of 054 from bmpd, the folks from mycity-military saved it in time , fortunately.

Btw , regarding these laughable claims of the F-119 being "40,000lb-18,000kgf". First, there was the claimed figure of 35,000lb . Then some wise guy with" inside" info came along and said 37,000lb . Then another one with more" inside info" upped it to 39,000lb. Now it's 40,000lb lol. Probably next year it's going to be even more. Same with the F-35 engine , it somehow went from 43,000 to 55,000lb pounds ( beats me how, imagination perhaps)!

Anyway , aparently an F-22 PILOT said once that the thrust of the F-22 totals 68,000lb ( 34,000lb per engine). He may have talked at some children gathering or something like that, but i think because of the circumstances he may have became careless, he slipped it by mistake . He could have just said 70,000lb the kids wouldn't know the difference.

I am betting that's the real F-119 thrust figure, just like that "25,000 lb" for the F-100 turned out to be 23,780 lb or something like that.

Anyway , sorry for the off-topic.

 

[sferrin]

I think that's the high-rez of 054 from bmpd, the folks from mycity-military saved it in time , fortunately.

Btw , regarding these laughable claims of the F-119 being "40,000lb-18,000kgf". First, there was the claimed figure of 35,000lb . Then some wise guy with" inside" info came along and said 37,000lb . Then another one with more" inside info" upped it to 39,000lb. Now it's 40,000lb lol. Probably next year it's going to be even more. Same with the F-35 engine , it somehow went from 43,000 to 55,000lb pounds ( beats me how, imagination perhaps)!

Anyway , aparently an F-22 PILOT said once that the thrust of the F-22 totals 68,000lb ( 34,000lb per engine). He may have talked at some children gathering or something like that, but i think because of the circumstances he may have became careless, he slipped it by mistake . He could have just said 70,000lb the kids wouldn't know the difference.

I am betting that's the real F-119 thrust figure, just like that "25,000 lb" for the F-100 turned out to be 23,780 lb or something like that.

Anyway , sorry for the off-topic.

It's likely at *least* 40k. Consider the F100-232 made 37,100lbs thrust in testing with ~270lb/sec. airflow. The F119 has 335lbs/sec. airflow. You do the math. (The -232 benifitted from F119 tech.)

 

[lancer21]

Yes, in testing. But what is the actual rated value of the 232 again, considering things like reliability, TBO, fuel consumption and a myriad of other factors (f.e. like the nozzle design , to be F119 specific ) . There's a rather big difference between testing and every day reliable operations as i'm sure you know. Anyway, you can believe what you wish.

 

[sferrin]

Yes, in testing. But what is the actual rated value of the 232 again, considering things like reliability, TBO, fuel consumption and a myriad of other factors (f.e. like the nozzle design , to be F119 specific ) . There's a rather big difference between testing and every day reliable operations as i'm sure you know. Anyway, you can believe what you wish.

Rated for 32,500 in service. Again, do the math. Even if the F119 were no more efficient (unlikely) it still puts it over 40k.

 

[Radical]

Yes, in testing. But what is the actual rated value of the 232 again, considering things like reliability, TBO, fuel consumption and a myriad of other factors (f.e. like the nozzle design , to be F119 specific ) . There's a rather big difference between testing and every day reliable operations as i'm sure you know. Anyway, you can believe what you wish.

Rated for 32,500 in service. Again, do the math. Even if the F119 were no more efficient (unlikely) it still puts it over 40k.

But when they're running on the F-22, it won't be higher than 35000. Being higher in test stand doesn't mean higher when installed.

 

[overscan (PaulMM)]

Have a good source that says ~308lb/sec mass flow for the F135, which has same core but a larger fan (0.51 versus 0.3 bypass ratio) than the F119 and should therefore have a higher mass flow rate. Assuming say 280lb/sec for F119 gives 33,700lb in this theoretical calculation. Thats about as meaningful as your figure.

 

[sferrin]

Have a good source that says ~308lb/sec mass flow for the F135, which has same core but a larger fan (0.51 versus 0.3 bypass ratio) than the F119 and should therefore have a higher mass flow rate. Assuming say 280lb/sec for F119 gives 33,700lb in this theoretical calculation. Thats about as meaningful as your figure.

I've see 400lbs/sec. quoted for the F135. Got the 335lbs/sec. for the F119 from an F-22 article in Airtime Publishing's World Airpower Journal (or the newer gray publications they put out) FWIW.

edit: yeah I just saw the 308 figure in an old Jane's article. Will try to track down where I saw the 400 figure. Also I'm wondering if the 400 figure might have been for the X-32's JSF-119-PW-614 variant.

 

[chuck4]

Have a good source that says ~308lb/sec mass flow for the F135, which has same core but a larger fan (0.51 versus 0.3 bypass ratio) than the F119 and should therefore have a higher mass flow rate. Assuming say 280lb/sec for F119 gives 33,700lb in this theoretical calculation. Thats about as meaningful as your figure.

Did your source say anything about what the actual thrust from the F135 was when it was pushing through 308 lbs/sec? If so, it would be a useful plot point to develop some sort of massflow to thrust diagram, either a line plot, or surface plot. If it needs to be a surface plot, then look for what the appropriate 3rd dimension would be for the plot.

To me it seem a more fruitful to use a discussion to develop a vbroader and insightful picture into how things work, even if in the process one might make a few mistaken extrapolations, then to let the discussion degenerate into sterile bickering over a few data points.

 

[sferrin]

Have a good source that says ~308lb/sec mass flow for the F135, which has same core but a larger fan (0.51 versus 0.3 bypass ratio) than the F119 and should therefore have a higher mass flow rate. Assuming say 280lb/sec for F119 gives 33,700lb in this theoretical calculation. Thats about as meaningful as your figure.

Did your source say anything about what the actual thrust from the F135 was when it was pushing through 308 lbs/sec? If so, it would be a useful plot point to develop some sort of massflow to thrust diagram, either a line plot, or surface plot. If it needs to be a surface plot, then look for what the appropriate 3rd dimension would be for the plot.

To me it seem a more fruitful to use a discussion to develop a vbroader and insightful picture into how things work, even if in the process one might make a few mistaken extrapolations, then to let the discussion degenerate into sterile bickering over a few data points.

From a post over on F-16.net of the meat of the Jane's article:

"The JSF-F119 was the engine of the X-35 concept demonstrators, and because of the short time-scale it was in turn a direct derivative of the F-22's F119 engine.

In contrast, the F135 is optimised for the propulsion of the F-35, though it is likewise derived from the F119, and is thus a two-shaft low-BPR turbofan with an augmentor. On the basis of information released by 2005 the only significant difference between the two engines is that the F135 has a two-stage LP turbine (that of the F119 having a single stage). Whereas the F119 is loosely described as being "in the 35,000 lb (155.75 kN) class", and the JSF-F119 as being rated in the 170 kN (38,200 lb) class, the F135 is described as "in the 40,000 lb (178 kN) class." Indeed, it is likely that the F135 will eventually be developed to give power well beyond the figures given in the data below.

Apart from the broad outline given in the description below, because of its high security classification, little is publicly known of the actual hardware of the F135, apart from the overall opinion that, as the crucial blading is all fractionally larger, because of the greater mass flows, the engine should be exceptionally tough and durable. Pratt & Whitney has, however, been permitted to disclose some of the radical advances that this engine will introduce in the fields of self-diagnostics and health monitoring. Among technological "firsts" claimed for the basic F135 are on-wing (this simply means "with the engine installed in the aircraft") trim balancing, elimination of the need to rig the installation on replacing an engine, and the elimination of safety wire (previously used to ensure security of such items as nuts and bolts).

Ground-breaking PHM health-monitoring and self-diagnostics systems. The intention is that PHM, a new acronym which will become important (meaning Prognostics and Health-Monitoring), will automatically take account of any in-flight fault, or incipient fault, adjust engine operation and inform the pilot, and in real time transfer data to the aircraft's home base. Thus, any replacement components will be ready for retrofit as the aircraft lands, with the engine pronounced fit again (the plan is) in about 15 minutes, which is said to be a 94 per cent improvement over present times. Of course, that is based on the replacement of externals, not such items as turbine blades.

Externals, in fact, differ markedly from those of the F119 used in the twin-engined F/A-22, though accessories are grouped on the underside as in the ancestor engine. The F135 is expected to set a new low need for special maintenance tools, and to have every external item immediately available upon opening the large access doors with stealth-type zig-zag edges. Indeed, Pratt & Whitney says "all critical features" will be at once accessible. Objectives include a reduction in operating cost -- presumably compared with such engines as the F100-PW-229, for example -- of 50 per cent, and an extension in time between scheduled maintenance of 225 per cent (one F135 document even claims "Scheduled maintenance requirement eliminated"). To this end, PHM will make use of electrostatic and other sensors to monitor such parameters as debris generation, vibration, blade health and lubricating-oil quality. The suite of sensors will constantly monitor approximately 500 data streams, which will be integrated with the F-35's own systems. The complete PHM system has been developed in partnership with NASA Ames, which created vital data-fusion algorithms, NASA Dryden and NASA Glenn, with flight development to be carried out with a C-17. As noted previously, the aim is to predict the need for inspection or parts-replacement, so that, via a satellite link, the airbase or aircraft carrier knows the engine health before the aircraft returns from its mission.

Apart from the challenging 94 per cent improvement in fault-rectification time, other design objectives include a 35 per cent reduction in cost of ownership, compared to legacy systems, a reduction in fault-detection time despite a 50 per cent reduction in the number of maintenance technicians, three times the hot-section reliability, and a 225 per cent increase in time between shop visits.

Back in 1997 the JSF programme had firmed up into three major aircraft versions, conventional (CTOL), STOVL and carrier (CV). Today these are designated as:

F-35A Engine: F135-PW-100. This is the baseline version of the F135.

F-35B Engine: F135-PW-600. This engine differs from other versions in incorporating a vectoring nozzle, bleed-air ports for roll posts for lateral control at low airspeeds, and a forward drive shaft to the LiftFan to provide lift independently of the wings. The basic engine is identical to other versions.

F-35C Engine: F135-PW-400. This is almost identical to the F135-PW-100, apart from small changes in accessories, and elimination of materials not resistant to salty environments.


The following refers principally to the SDD engines:

Type: Two-shaft augmented turbofan, the F135-PW-600 version having additional STOVL features.

Intake: The intake hub is the same in all versions, being unaffected by connection of the LiftFan drive shaft.

Fan: Three integrally bladed rotors, derived from F119 but with new features giving greater mass flow with higher pressure ratio, improved stability, maximum resistance to bird and other impact damage, and minimum signature. Significantly lighter and less costly than predecessors, yet provides most of the thrust. The casing is the first to be made for the US military from organic-matrix composite (OMC) material. First-stage vanes (stators) hollow OMC, rotors 2 and 3 flank-milled titanium alloy. Split casing permitting reblading or minor repairs, and weld repairs are (mid-2004) being developed for all stages. Inside the nosecone a single bolt permits removal of the fan module in 40 minutes. This bolt is replaced in the Dash-600 engine by a connector to the LiftFan drive shaft. Inlet diameter 1,168 mm (46.0 in). Bypass ratio, (F135-PW-100, -400) 0.57; (F135-PW-600), conventional flight 0.56, powered lift 0.514.

HP Compressor: Six-stage SDD compressor derived from F119, rotating in opposition to LP spool. Split forward case in titanium alloy housing two stages of asymmetric variable-incidence guide vanes (stators). Cast nickel-alloy rear stators grouped in segments in titanium-alloy ring casing of high creep strength. All stators integrally bladed, either flat-milled like the fan or high-speed milled. All six rotors integrally bladed, first two in damage-tolerant titanium alloy, the remainder high-strength nickel alloy. Crucial No 3 bearing is a simple squirrel-cage unit, lighter and easier to install than the corresponding bearing in the F119 (which comprises a ring and 24 rods). The production bearing may be made of corrosion-resistant silicon nitride hybrid ceramic. Mass flow (F135-100) 139.6 kg (307.8 lb)/s. OPR (F135-PW-100, -400) 35, (F135-PW-600) conventional flight 34, powered lift 29.

Combustion Chamber: Short annular diffuser/combustor, derived from F119. Outer casing including HPT nozzle ring (lighter and less costly than in previous P&W fighter engines), handling airflow at 4,150 kPa (600 lb/sq in) at 649°C (1,200°F), and containing air-conditioning connections and inspection ports. Liner with impingement and film cooling containing Floatwall ceramic-coated nickel-based cast segments, each containing "thousands of holes", which "float" from their anchored location. Intense combustion with fuel/air ratio 20 per cent higher than in F100 engine to give near-record gas temperature exceeding 2,200°C (4,000°F).

HP Turbine: High-work single stage based on F119, with advanced airfoil coating and cooling derived from F119, but with cooling airflow doubled. Impingement cooling augmented by closing down rear stator angles. Nozzle ring organic-matrix vanes. The rotor comprises a main disk, miniature disk and cover plates, all incorporating the same high-strength powder-metallurgy (sintered) high-rotor blades of second-generation single-crystal Ni-based alloy, with advanced outer air seals. The HPT rotates at speeds exceeding 15,000 rpm, generating 47,725 kW (64,000 shp) from gas at just over 1,649°C (3,000°F), cooled by air supplied at 538°C (1,000°F) from the HPC. To minimise pressure loss the rotor blades are cooled by Tangential On-Board Injection (TOBI), each blade being a complex casting with multiple cooling passages. Growth in blade-tip diameter is controlled by a unique slow-responding thermally isolated support ring in materials selected for their low thermal expansion, giving passive clearance control through the normal engine-operating range.

LP Turbine: Two-stage design giving significantly greater shaft power than the single-stage LPT of the F119. Rotates in opposition to the HP turbine. Typical of the simplified design of the F135 are the main shaft bearings, (see note under HP compressor), and it is possible that the full production F135 may have a corrosion-resistant ceramic (silicon nitride) bearing. In the F135-PW-600 the LPT torque is transmitted through the fan and a dry-plate clutch to the LiftFan drive shaft, the turbine power being shared by the two driven items. Casing fabricated in refractory nickel and Pratt & Whitney proprietary materials. Supports aft-bearing compartment, whilst diffusing and turning the 1,093°C (2,000°F) efflux with minimum pressure loss (see next).

Afterburner: Large-volume with advanced flame-holder system. Fully variable convergent/divergent nozzle, with 15 hydraulically driven hinged flaps, controlling propulsive jet at 621 kPa (90 lb/sq in) at up to 1,927°C (3,500°F). Unique pressure-balance system to assist the hydraulic actuators which vary area and profile, and also to assist bypass air to reduce area when maximum loads are encountered. In the F135-PW-600 the complete nozzle can vector through 95° in 2.5 seconds to give 80.34 kN (18,000 lb st) lift force for STOVL. The Dash-100 and -400 LO axi-symmetric nozzle; The Dash-600 3BSM (three-bearing swivel module) has shorter variable flaps. It was designed to be able to bolt directly on to the STOVL version of the rival F136-GE-600 engine.

Accessories: Accessory gearbox driven off main HP shaft. Integrated Power Package (IPP) comprises the engine-start system and the F-35's Auxiliary Power Unit (APU). Dual fixed-displacement vane-type fuel pumps (the gear-type originally used added too much heat), with servo valves. Fuel/oil heat exchanger. Advanced prognostic and on-condition health-management systems. Commercially developed fire containment system."

 

[chuck4]

The 18000 kgf figure is based on Lockheed's statement that the F-22's PW F119 was already 20% more powerful than the 15000 kgf class Tumanski R-79V-300 engine used in the Yak-141, and therefore was more than adaquate for use in a future single engined STOVL fighter. This was near beginning of the JSF program in the 1990s. I'll try to dig that up.

 

[overscan (PaulMM)]

Hard F-119 info is elusive.


Here's something from a RAND report:

 

[overscan (PaulMM)]

Jay Miller says military thrust is 23,500lb and "35,000lb class" with afterburner.


This gives a ratio of 1.5:1 between military and afterburning thrust which is basically identical to the F-135.


Rand report says

F119PW-100
Intermediate thrust:20,500lb
SFC: 0.80
OPR: 26.0
Rotor entry temperature: 3,000
T/W ratio: 7.95/5.25
Mass Flow: 270lb/sec
Dry weight: 3,900lb

Rand report gives F100-PW-229 as

F100PW-229
Intermediate thrust:16,999lb
SFC: 0.70
OPR: 26.9
Rotor entry temperature: 2,730
T/W ratio: 8.53/4.9
Mass Flow: 248lb/sec
Dry weight: 3,400lb

 

[overscan (PaulMM)]

AL-31F baseline

Maximum dry thrust: 17,130 lb (+-2%) (100%RPM)
Minimum afterburning thrust: 18,629lb
Maximum afterburning thust: 27,500 lb(-2%)
SFC: 0.75 @ maximum dry thrust (0.67 at economic cruise, 85-90% RPM)
OPR: 23.0
BPR: 0.571
Rotor entry temperature: 2538 F
T/W ratio: 8.1/5.08
Mass Flow: 246.9lb/sec (+4.4lb, -2.2lb) at all thrusts
Dry weight: 3,350-3370lb
Diameter: 48 inches (max)
Length: 16.2ft

 

[overscan (PaulMM)]

Note that intermediate rated thrust = maximum dry (non-afterburning) thrust.


Also note the given T/W ratio and dry weight give F119 an afterburner thrust of just 31005lb, while the F120 on the next page is given as 20,300lb dry and 32520lb with afterburner. Development engines perhaps?


20,500lb to 31005lb is 1.5:1 ratio again.

 

[overscan (PaulMM)]

Salyut AL-31FM3 increased temperatures to 2870 F and put in a new blisk based fan with increased mass flow to achieve 15,200kg from an AL-31F derivative (Sukhoi preferred Saturn's 117S/117)

AL-41F (original) started development in 1985. It was supposed to achieve 10:1 - 11:1 thrust/weight ratio with TET of 2912 F and use all modern techniques and materials. In total 25 engines were built, the first flew in 1990 in an Tu-16 testbed. Reportedly the test engines achieved 176kN (39,680lb) afterburning thrust.

 

[sferrin]

Note that intermediate rated thrust = maximum dry (non-afterburning) thrust.


Also note the given T/W ratio and dry weight give F119 an afterburner thrust of just 31005lb, while the F120 on the next page is given as 20,300lb dry and 32520lb with afterburner. Development engines perhaps?


20,500lb to 31005lb is 1.5:1 ratio again.

I wonder if the got their numbers screwed up. Sounds like they grabbed the numbers for the YF119 used in the ATF competition. On top of that, the only way you're going to see that big of jump between mil and afterburner is with a very high bypass ratio - which the F119 isn't.

 

[kaiserbill]

Interesting posts, Paul.

Thanks.

Was funding the primary cause of not developing the original Al-41 further?
Or was it the issue of size, as in the new Al-41F1 (117) as used in PAK-FA could be more easily integrated on existing Su-27/30/33/34/37 airframes?

 

[flanker]

By all accounts i have heard Al-41 was a terribly unreliable bastard, and it never achieved designed trust. I remember "15 tons" at max for some reason, unsure where from or if it is correct.

 

[kaiserbill]

A report from Flight dated 1995 about the original Al-41, put here for information purposes relating to the PAK-FA's powerplant which is, from all descriptions I've seen, "based" on the AL-31 core, but with technology from the original AL-41to create the new engine.

Note that this is from before the flight of the Mig 1.44.

MIKOYAN'S FIFTH-generation fighter, the Article 1.42, has been fitted with
Lyulka Saturn AL-41 next-generation engines, with the engine-design bureau
claiming that previous engine problems have been overcome.


Victor Chepkin, Lyulka Saturn president and chief executive, says that the
AL-41s installed in the Mikoyan technology demonstrator, shown in June to
Russian defence minister Gen. Pavel Grachev, are development engines rather than
experimental.


He adds that, as installed on the aircraft, these include circular
thrust-vectoring nozzles. Circular- and box-nozzle thrust-vectoring
configurations are thought to have been examined.


The 1.42's first flight has been delayed repeatedly, with Mikoyan saying that
this was partly the result of problems with the power plant.


Chepkin claims that AL-41 performance "... is in no way inferior to the Pratt
& Whitney F-119 engine powering the F-22". The AL-41 is a fifth-generation
engine distinguished in principle by "...absolutely new aerodynamics, ie all
compressors and turbines were designed and developed exclusively using a
three-dimensional computer model," he explains.


The design also includes advanced materials, including high load-bearing
titanium alloys and compacted heat resistant powder alloys for discs, shafts and
load-bearing body parts.


Chepkin says that a qualitatively new level of turbine-inlet temperature has
been attained in the AL-41 design adding 250°C to the value achieved in the
Lyulka AL-31, now powering the Sukhoi
Su-27/Su-33, which required a new level of technology for blade cooling.



The high inlet temperature is necessary to allow the aircraft to "super
cruise" -that is, to cruise supersonically without using reheat. The AL-41 has
already logged a "sufficiently high number of hours" in flying testbeds.


Specification figures for thrust, specific fuel consumption and acceleration
time have been met, according to Chepkin, but the turbofan has a limited
guaranteed life.

 

[kaiserbill]

Back to the current engine on the PAK-FA, I've seen 2 reports.

One states that the current engine is designed, with development, to give thrusts in the 14,7kN-15,5kN range. Note that the lower value is what has currently been officially stated by Pogosyan as the thrust of the current engine.

Another report has stated that there will be a "second stage" that will provide "around" 11,7,kN dry, and 17,1kN in afterburning, and will be available for testing in 2014, according to Evgeny Marchukov, General Designer/Director of Lyulka. This was apparently stated in November 2012.

Not sure of the veracity of the above, but this is what I found after a 20 minute internet delve into matters.

 

[chuck4]

The AF-41 technology that migrated to AF-31 probably involve new materials for combustion chamber and turbines to accept higher temperature. Information quoted above suggests AF-31 continues to have a substantially smaller fan and lower turbine temperature than the F-119. It's not clear to me how an engine's thrust can keep going up when we know the massflow is limited by size of the fan, density of air and the fact that incoming air has to be subsonic. And exhaust energy is likely constrained by combustion chamber exhaust temperature. If it's somehow a trick with the afterburners, then that contradicts the claim that the changes favilitates super cruise.


These days Russian military aircraft industry is substantially more mercenary and commercial than the leading western competitors, and its future depends to a much higher degree on sales to foreign powers, some of which are not of the highest technical sophistication. So I would expect the Russians to suggest in public channels that whatever the truth, its future equipment has boundless potential for growth.

 

[kaiserbill]

Chuck4, I find it humourous to suggest that the Russians present only the best side of their projects, or stretch the truth, whilst the valiant West only stick to the absolute truth.

Let's rather stick to the facts as found, or neutral thoughtful analysis so as to preserve this thread, which has the potential to be excellent.

When you say " the AF-31 continues to have a substantially smaller fan and lower turbine temperature than the F-119" do you mean the Al-31, or Al-41 as found on the PAK FA?

 

[chuck4]

Chuck4, I find it humourous to suggest that the Russians present only the best side of their projects, or stretch the truth, whilst the valiant West only stick to the absolute truth. Let's rather stick to the facts as found, or neutral thoughtful analysis so as to preserve this thread, which has the potential to be excellent.

Kaiser, I suggested no such thing. I find it humorous that you would put words into mouth in order to protect a veneer of condescension. Neither condescension, nor putting words into other participant's mouth, could but damage the excellence of a thread.

When you say " the AF-31 continues to have a substantially smaller fan and lower turbine temperature than the F-119" do you mean the Al-31, or Al-41 as found on the PAK FA?

I mean the AL-31 derivative restyled as the AL-41. Based on my information, this AL-41 has fan diameter of around 930mm, while F-119's fan diameter is over 1000 mm, probably in the region of 1100mm. The AL-41 has turbine inlet temperature of 2850-2900F, while F-119's TIT is 3000F.

 

[overscan (PaulMM)]

Why do you keep saying AF-31 instead of AL-31F? Its very irritating.

 

[chuck4]

Why do you keep saying AF-31 instead of AL-31F? Its very irritating.

Because I don't want to confuse derivatives of AL-31 with the original AL-41.

 

[kaiserbill]

When you say " the AF-31 continues to have a substantially smaller fan and lower turbine temperature than the F-119" do you mean the Al-31, or Al-41 as found on the PAK FA?

I mean the AL-31 derivative restyled as the AL-41. Based on my information, this AL-41 has fan diameter of around 930mm, while F-119's fan diameter is over 1000 mm, probably in the region of 1100mm. The AL-41 has turbine inlet temperature of 2850-2900F, while F-119's TIT is 3000F.

How do you know the AL-41F1 has that diameter?
No information has been released on its fan diameter.

Ditto for the F-119.
I have seen no officially released statistic on its fan diameter.
If anybody has information on that, I would be grateful.

What I do know is that the basic AL-31F has a fan diameter of 905mm.
The AL-41F1A (117S) has increased this to 932mm. (This powers the Su-35)
The AL-41F1(117) that powers the PAK FA, and which it's designer has stated is a different engine, has not had its fan diameter officially released.


I think you are getting mixed up between the engines again as in your post a while back in the thread?
Or assumed they have the same diameter?
Quite understandable, as the designations are confusing, as I've said before.


Any statement on its fan diameter is thus conjecture, until official figures are released.
They may be the same diameter, or may not.
I say the same thing about the fan diameter of the F-119, unless I'm missing something, and a fellow forumite can point me to an officially released figure?

The Al-31 has a turbine inlet temperature of 1412 degrees Celcius.
The AL-41F1(117) has been stated to better this by 250 degrees Celcius.
That means the AL-41F1(117) has a turbine inlet temperature of 1662 degrees Celcius.
1662 degrees Celcius = 3023F.

Your figures almost seem designed to peg everything just slightly lower.

I am getting my figures from open source, public domain statements from the designers admittedly, but that's all we have to go on.

 

[kaiserbill]

Why do you keep saying AF-31 instead of AL-31F? Its very irritating.

Because I don't want to confuse derivatives of AL-31 with the original AL-41.

But you're confusing us as much as the Russians are. ;D

Why not just use the official nonclemature?

 

[Wil]

But the latest, evolved model AF-31 is still a good 25% less powerful than the base model PW F-119.

Is it a joke?
;D ;D

No. The latest AF-31 derivative is the AF-41F1 (117). The director of Sukhoi claims this is the intended engine for PAK-FA. 117's is rated around 14500 kgf with AB. The F-119 is classified but likely in the 18000 kgf range with AB. The F135 derivative is >20000 kgf

With 117 engine, T-50 needs to have a combat weight at least 6-7 tons lighter than F-22 in order to match F-22's current t/w ratio. If T-50 turns out to be of similar weight as the F-22, then with 117 engine its thrust to weight ratio with AF would be in the uninspiring F-4 phantom territory.

And T-50 is bigger than F-22 in every dimension, and some claim it also carry a much larger internal fuel load then the F-22. I suspect it won't be 6-7 tons lighter than F-22.

Unless the Russians resurrect the original AF-41 program for the Mig 1.44, not the current jumped up AF-31 that's been restyled as "AF-41F1" , I don't see a F-119 class engine in T-50's foreseeable future.

So I am guessing T-50 won't be fully competitive against the F-22 in every part of its envelope in every measure of maneuverability and agility.

A Flanker used to test the new engine Saturn 117. This engine has a larger diameter and superior thrust than the Al-31 family.


http://img690.imageshack.us/img690/7783/flanker117test.jpg


From the web:


"The Saturn 117 (AL-41F1) is a new 5th generation engine custom built for Russia’s fifth-generation stealth fighter jet PAK-FA according to Sukhoi General Director Mikhail Pogosyan. Mikhail


Pogosyan has clarified that claims that fifth-generation fighter allegedly has an old engine are wrong. Such claims are made by people with limited knowledge, he said. Though most parameters


of the new 5th Gen Engine remains classified General Director Mikhail Pogosyan provided some information on the new engine, the engine thrust was enlarged by ~2.5 tonnes when compared


with the AL-31 engine, while the engine weight was cut by 150 kilograms. That allowed the new jet to supercruise i.e. move at a supersonic cruise speed without the use of after burner".


If the Saturn 117 has ~2.5 tnf more thurst than the Al-31, this implies the real thrust of Saturn 117 is 16-17 tnf, similar to the trust of F-119.


Please look at this picture. Do you really think that this engine is less powerful than the F-119?


http://imageshack.us/a/img89/1340/pakfaatras1.jpg


Best wishes!