LMFSOne of the stated goals of izd.30 is lower maintenance and operating cost. Especially since izd.117 is considered not economical to run. More power is not the only goal of izd.30, higher MTBO and better operating economy are major goals.
Do you have sources for the claim in bold letters? While the reduced number of stages is coherent with claimed easier maintenance, the engines of the Al-31F family are among the ones with better fuel economy. Izd. 117 has essentially state of the art combustion, they would not get a serious improvement in TSFC unless they reduce the BPR, and that makes little sense if you want to produce a high specific thrust engine. Also the maintenance of the 117S is much better than old Al31F with 4,000 h operative life, I don’t have the data for the 117 but considering it is the premium, non-export version of the 117S, I would assume it is not worse in that parameter either. Furthermore, Marchukov said izd. 30 keeps the TSFC of the AL-31F, so no apparent improvements are to be expected there. The achievement is to have the specific thrust of a turbojet and the TSFC of a relatively high BPR turbofan.
Here is diagram of F-22 fuel tanks, you can see the two rear tanks by the engine bays.
Great, thanks. Indeed there are two relatively big tanks in the rear fuselage. I wonder what would be their capacity is (the picture posted above seems to overstate the values, see more below) and what was the capacity of the same tanks in YF-22.
From my limited experience fooling around with 3D modelling I can say that nothing adds volume like a good dorsal tank, because it is wide, deep and long, unlike other tanks that are very limited in one or two dimensions. In the case of the F-22, it is easy to see that the dorsal tank is relatively swallow due to the air ducts and loses all the space occupied by the side bays, which would be as big as the rear fuel tanks at least. That is where I would expect improvements to be done, in order to reach internal fuel values in line with those of a Su-35.
The tank capacity shown in the picture by paralay shows a total 13,029 l internal fuel, which taking 0.8 kg/l for JP-8 (I got density values between 0.775 and 0.840) results in 10.423 kg, 2.2 tons more than the supposed internal fuel of the plane (8,200 kg), makes that sense to you?
The much steeper reduction in drag coefficient when Mach increases is for only individual components like the wing or a generic object. When you have a whole aircraft the total supersonic parasite drag buildup will include things like shockwave interference and total area rule and volume distribution. So even with a dedicated interceptor like F-106 where drag reduction was emphasized over pretty much everything else you don’t see that steep kind of drag coefficient reduction of just a component.
XB-70 drag coefficient is low because wing is huge (drag force is drag coefficient times dynamic pressure times wing area), and also that aircraft is optimized to the extreme for supersonic flight. Also small wings is why F-104 drag coefficient is so high even though actual drag is actually very low.
I see, that makes sense. The Su-57 has very big wings and is relatively flat / airfoil shaped overall, but of course I cannot quantify in what final Cd that translates.
~35% increase in thrust will get you from Mach 1.3 to Mach 1.6-1.7 at best. For example YF-22 supercruise speed is Mach 1.43 with YF119 and Mach 1.58 with YF120 which is 20% more powerful because of the YF119 didn’t have the bigger fan for increase mass flow of production F119, while YF120 did.
You may be right, maybe the Su-57 has a better aero than thought and reaches more than M 1.3 with current engines, if you check I assumed up to M 1.5 in my first post. But my idea is not to produce accurate quantitative values, because that would be absurd given I am no expert and don’t have the necessary data. I am only meeting the dots between what makes sense from a program point of view and what known evidence and official claims support, to reach a qualitative estimation. That would be: supercruising available with current engine but with speed values well below those of F-22, with second stage engine cruising speed equal or bigger than that of F-22 and actually the real possibility of it being close to 2 M, given the number of aspects in which the Su-57 /izd. 30 design offer advantages vs. F-22/F119.
Going to your data and trying to understand your view:
– How did serial F-22 managed to reach cruising speed of M 1.8, given the values you refer for YF-22? Engines were improved massively or drag reduced also massively?
– What is your expectation regarding cruising design speed of a mature Su-57, considering the data already provided by Marchukov?
– How do you make sense out of the fact that Russia decides to produce a new engine, while still developing the 117, in a sequence that does not even allow it to pay-off? My take is that the 117 is the B-plan or risk reduction measure for the program, that will flow into the Flankers in the future, and which covers the eventual failure of the izd. 30 to deliver. But Russian sources are quite consistent considering that supercruise is a crucial requirement of the 5G planes and identifying that with variable cycle, so I assume that from the beginning the idea was to have an engine pretty much like the izd. 20 but in the appropriate size and with modern technology, which is my understanding of the izd. 30 in few words.
LMFSIF you read the full quote they are referring to current engine , You cannot talk about something that does not exist other than prototype.
The interview of Deputy Chief of RuAF I posted also spoke of Supercruise exist for PAK-FA.
I am not so sure, but it is just my opinion. In any case they are not being precise. A said, it is not the same 1.1 M than 1.8. And they by now know for sure the final performance of the plane with the second stage engine with almost total certainty.
If it was not because izd. 30 brings much better cruising speed, why would they bother designing it, so close after having done the izd. 117 with a max thrust almost in the level of the F119?
As far as SC at what mach number I think that would vary depending on Fuel load and weapons load it is carrying.
Would vary indeed but I assume it would be by a small margin, given the internal carriage of weapons and low wing loading of the plane.
F-22 does have two major fuel tanks in rear fuselage by engine bays where it is much slimmer compared to YF-22 prototype.
I will check that, thanks
When you get out of transsonic and into supersonic at Mach 1.2 or more drag coefficient does not decrease that much.
Look at even some of the most area ruled aircraft ever made like RA5C and XB-70, these have much better fineness ratio than any 5G fighter.
Wow XB-70’s Cd is ridiculous… I have seen other drawings with much steeper reductions of Cd as speed increases, it depends on the design and I cannot make statements about how it behaves in the Su-57. Keep in mind the trimming options they have with the TVC and LEVCONS to reduce drag in supersonic flight too, everything in the design has been conditioned by this flight regime. Of course, I am aware that drag increases non linearly with speed, but the fact that F-22 can cruise so fast with an engine size and cross sectional area very close to Su-57 despite allegedly not being as aerodynamic as the YF-23 supports that a cruising speed in that ballpark for the Su-57 is perfectly possible, besides being a logical design goal both for the plane and for the second stage engine, designed as said above immediately after the 117 was developed and hence still up to date. As argued other evidence suggest that the installed thrust of the 30 is equal or bigger than F119, maybe the radar blockers being the only negative issue I can think of.
Obviously dynamic thrust is harder to estimate but assuming izd.30 can get twice the dynamic thrust of izd.117, which was already much more optimized for supercruise compare to base AL-31F is questionable. You can’t directly compare afterburning thrust of F100 to military thrust of F119, their dynamic thrust profile will be different since afterburner increases exhaust temperature behind the turbine where the combustion gasses already went through some expansion.
Why twice the dynamic thrust of izd. 117? I simply assume it will be equal or better than F119’s, that has as said 25-35% more uninstalled mil thrust, mainly due to lower BPR. A change in BPR between izd. 117 and 30 would get most of the work done, I assume.
Re. the different thrust profiles w/ and w/o AB, I am aware the comparison is decidedly rough but still applicable. Do you have some data to help refining it?
BTW, it seems today is a busy day showing the Su-57 😀
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LMFSOnly reference to “Mach 2” supercruise has been hearsay from “radioscanners” that Berkut (who got banned here for some reason) states to be false.
I have read it as of late a couple of times, once from a guy that had name and reputation. I will try to find it.
I’ve asked on Secret Projects and both flateric and Berkut (he’s called Flanker on Secret Projects) reject it.
Well, don’t forget that perspective and available sources change with time. Besides those two persons, which I just know by reference, may not know all about PAK-FA. And if they know, they will better not say anything because they know for sure what consequences disclosing info in forums can have.
Besides, flateric points out the ORIGINAL max speed requirement was Mach 2.35, and in 2006 that was actually reduced a bit because of structures and materials.
The keels would have needed reinforcement, this is a known story. But were they meaning max speed or max cruising speed without time limitations? I cannot be 100% sure. The argument of the intakes speaks IMO quite clearly in favour of max speed beyond 2 M.
Also I don’t think there would be dedicated PAK-DP program if PAK-FA is meant to have Mach 2 supercruise.
PAK-DP will be an interceptor where the constraints of a multirole design will be cast aside. That means, min drag instead of max lift, huge fuel load, specialised engines and so on. It is supposed to be highly supersonic (4 M) and have long range, probably quite a big beast born out of the need to fight future hypersonic threats, very different to the PAK-FA.
The 2 M supercruise would respond to the reality that F-22 is essentially there already, so being in that ballpark is a need. And PCA is claimed to be about speed, range and payload again, so Russia needs a bit of margin beyond F-22.
Though in all honesty the king of speed for fighters would probably have been F-23, that has better area ruling than any fighter, but it didn’t get chosen.
And not less importantly, YF120 was also not chosen. But now time has passed and Russia may decide differently to the US and go for a more ambitious approach.
Also, AETP is meant to improve acceleration and fuel efficiency in F-22 and F-35, not speed.
Cruising speed yes, since it will notably increase the thrust in mil settings. Ratio between mil and max thrust will change greatly as far as I know.
Beyond the gains due to pure technological progress between engine generations, the layout change will bring more subsonic range to the F-22 and maybe some lelvel of supersonic cruise to the F-35.
In fact if you see F-35 flight envelope you see that the flight performance just cuts off at Mach 1.6 instead of having a curve that stops at Mach 1.6. This means F-35 is not limited to Mach 1.6 by drag, but it’s an “imposed” limit, so even with more powerful engine the max speed is not going to change.
Probably true, maybe due to maintenance requirements for the coatings or restrains on dynamic pressures (maybe born of weight-out measures?). It seems self-imposed in any case, so may be changed in the future if the conditions change too.
Most publications such as AFM and Air International puts it at Mach 1.82 and general consensus is Mach 1.8. But F-22 makes some pretty big sacrifices to supercruise at this speed, such as quite low bypass engines that are pretty thirsty,
That is the crucial question, do you sacrifice operational cost and range for the whole operational life of the aircraft to be a beast in kinematics during some brief fight moments? Or do you favour a high bypass engine, even when it will not be capable of supercruising? Russians seem to be convinced of wanting both range and speed, at least from what I read this is the key behind izd. 30.
and also very tapered rear fuselage which reduce wave drag but also reduces quite a bit of fuel volume, so range is not great. Also weapon bay is quite shallow
That is why the layout of the PAK-FA is so special. They managed big bays but placed them one after the other along the longitudinal axis of the plane and in the shadow of the unavoidable, drag-generating nose & cockpit sections, so pretty much got that volume for free. Fuel capacity is granted by the extremely developed blended wing-body design. The rear fuselage usually holds not much fuel in almost any plane, with maybe the F-35 holding a bit more than normal. The problem with the fuel in the F-22 is that it has a very short middle fuselage section, together with volume-eating S-shaped air ducts and outright huge side weapon bays. Together with the low BPR engines, this creates a certain lack of range which poses a challenge if the plane has to operate in a contested airspace of a certain depth, a good reason why PCA is being fast tracked instead of modernizing the 22.
If izd.117 allows supercruise of Mach 1.3, then it’s VERY unrealistic for izd.30 to give Mach 2 supercruise because once you’re out of transsonic and in supersonic, drag is pretty much increases with square of speed, so Mach 2 drag is 78% higher than Mach 1.5 and 136% higher than at Mach 1.3. So while izd.30 will definitely be big improvement over izd.117, it won’t be THAT big.
First of all, I don’t have any proof and also have not made numbers, good or bad about that speed. But I think others would go along that figure of M1.3 for izd. 117 so I will follow your reasoning.
The drag question: what you say is true but not all the truth, since Cd changes with the speed and decreases notably, well beyond the transonic region. This change depends on the particular design, and judging by the wing sweep for instance, supersonic performance was a big issue for the Su-57, as the patent also confirms. Area rule is very apparent too.
The issue with izd. 30 and izd. 117 is that the first is not a further evolution of the later or even keeping the same layout, so you cannot estimate its thrust as a pure linear progression from the older model. Not only has it a very much reduced number of stages but most crucially it has been designed specifically for supercruise. This is proven not only by the many times this requirement is argued by officials and designers as the justification for spending even more money after the already modern izd. 117 was completed and tested, but the words of its lead designer confirm the crucial parameter of such an engine, specific thrust, to be the highest available in any engine of that category. So either they have way higher temps and compression than the F119 (improbable) or they have lower BPR.
Think of it this way: what mil thrust does F-22 need to fly 1.82 M? 11-12 tf/engine, to account for detuned specs. Izd 117S, which is a bit worse than 117 but of the same design, 8.8 tf. That is a massive 25% – 35% difference. That level of thrust is similar to what an engine of the F100-AL-31F generation needed to propel 4G jets beyond 2 M. Intakes in the Su-57 are simply huge with the best pressure recovery due to adjustable ramps and relatively straight air ducts, and besides the ram compression will keep adding thrust to the engines as the speed increases. So not so crazy IMHO to think that a carefully designed fighter whose cross-sectional area is not bigger than that of a Flanker can get to that speed with engines capable of 12 or more Tf. The exact number will maybe never known but this estimation makes reasonably good sense to me…
LMFSThis one again confirms that 117 Engine can supercruise PAK-FA
It is unclear if they refer to Su-57 with current engines or not…
In any case it is not the same to “supercruise” at 1.8 or 2 M than barely maintaining M > 1 for some minutes. The first has a clear tactical value, the later, not really. We don’t know what the izd. 117 allows to do. The designers said that it fulfilled the MoD requirements, but clearly an engine as izd. 30 (designed for supercruise) should improve over that by a big margin, so what were the original requirements? Was there a “nice to have” requirement that latter evolved into a “must”, as the progress with the design of the izd. 30 allowed for more ambitious goals? IMHO and all that being considered, the Su-57 with the current engine maybe cruises at 1.2 – 1.3 M, maybe 1.5 M being very optimistic, with the second stage engines should be close to 2 M.
LMFSHmm so I guess the stealth problem in the back will be addessed in the future regarding this mock up design of the SU-70?
Indeed it looks like this is the plan. Coherent with the design of a stealthy, subsonic deep strike and intelligence platform that cannot rely on kinematics to defeat air defence.
Su-27 early series had an empty weight 16380 kg. Later series, including Su-27SK – 17500 kg
Ok thanks, I will research a bit on that
LMFSSu-35S, the volume of electronic equipment has decreased. Its density if I am not mistaken 320 kg/m3. In its place filled with fuel density of 800 kg/m3.
I am referring to empty weight, which in your table is 19,300 kg. I need to check in detail, but Su-27 was less than 17 tons if don’t remember wrong.
Heavier nozzles and engines with increased resource, they are also heavier.
According to Rosoboronexport, the Al-41F1S is 84 kg heavier, so 168 kg difference, you are right. AL-41F1 is supposedly lighter, 150 kg less than AL-31F.
Reinforced wing, now there can be suspended external fuel tanks 2 x 2000 liters. This required strengthening the structure, logically.
True, this may be a major contributor but I assume modern production and materials should help increase the resistance of the structure with little weight increase. If not, all the progress in the engines would be negated by the increase in empty weight and Sukhoi would fail to improve the kinematic behaviour of the plane.
Su-57. The selected angles for the nose cone and air intakes clearly indicate a maximum speed of at least M=2.35 (2500 km/h) The selected angle of the leading edge of the wing implies a high cruising speed, probably M=1.78 (1890 km/h)
I tend to agree and would stretch those figures even a bit further. Latest data I saw which seemed half reliable (a supposed expert whose article I need to dig up) indicated cruise speed 2 M, max speed 2.45 M (2600 km/h). Few months before I would have thought this to be far fetched, now after reading Marchukov and the patent I tend to think it is actually realistic:
– No reason for 15 years of delay to create a weapon against F-22 which is clearly inferior from the beginning. F-22 can supposedly cruise at 1.82 M, max speed is 2.25 M IIRC
– Izd. 30 is stated as being the engine with highest specific thrust in its category available anywhere.
– Supercruising performance is one of the main design focus of the plane, as stated in the patent and obvious from many design traits.
– It makes no sense to incur the effort and expense of designing a variable intake which is only better above 2 M (as stated in the very patent) if your maximum speed is not substantially higher than that.
– F-15 is still very much in service and will continue to do so for the foreseeable future. Its max. speed is 2.5 M, so it makes sense for Su-57 to be at that level too, in order to dominate the engagements with superior range and markedly better cruising speed / acceleration.
USAF’s best chance IMO is to bring AETP engines to the F-22/ F-15 / F-35 fleet, in order to counter the more than probable advantage in kinematics of the Su-57.
LMFSOr maybe the aircraft was just very light, little internal fuel? Impressive none the less…
Light or heavy, I have not seen this before. Undercarriage, aero, control and structure all play a role in order to allow for such a hard landing. This is a highly valuable characteristic in case of a real, large scale conflict, let us not forget it.
LMFS1.T-50 with engine izd.30
2. T-50 with engine izd.117
Thanks paralay, I only had the table with the izd. 30 values for the Su-57 but not those for izd. 117. As usually, I am left wondering where the data come from, apart from attentively following sources and using your drawings, that I by the way consider very accurate and a valid reference. My comments nevertheless:
– Su-35 weights 3 tons more than Su-27? Why? The Flanker was a very big plane in not a small part due to old systems technology of the USSR demanding a big airframe. Nowadays this is not the case anymore, as we see in the reduced size of the Su-57 and in the increased fuel capacity of the Su-35 compared to older Flankers. Maybe a good calculation could be done based on known empty weight of older Flankers and publicly available acceleration values of those and Su-35.
– Per official data, uninstalled military thrust of izd. 117S is 8800 kgf, that would mean 17600 kgf instead of 17740 as in your table
– To the estimation of izd. 30’s thrust: ratio with and without afterburner seems improper of a supercruising engine, it keeps the same relation seen on izd. 117S but with increased values. On the one hand, the military thrust seems a bit low considering statements that it will have a higher specific thrust than F119. So, due to similar size to F119, thrust should be also higher, as supported by claims (which I increasingly start to believe) that Su-57 will cruise at ca. 2 M. The maximum thrust seems high, would demand really high airflow for an engine that should have roughly the same diameter than izd. 117 and besides its bypass ratio should be lower than the later. What I would really underline is the intake design that will probably allow for very high installed performance, especially at high altitude due to oversized capture area and variable ramps. The plane is clearly optimized for kinematic performance at high altitude / supersonic flight.
LMFSOkhotnik, with flat nozzle and somewhat changed wing tips:
LMFSSTOL performance, proven
LMFSMax sustained Turn rate is no better vs Su-27S, its probably less when the Su-35S is carrying a lot of fuel, but similar at low fuel. Aerodynamical, the Su-35S is give or take 2 tons heavier, but it has four tons of extra thrust, and it is debatable if the TVC can actual help the sustained turn rate. Around the corners no doubt yes, but say you are in a merge and have to stick at it, perhaps not.
But one thing is clear, no same jet fighter pilot would do the verticals in the egg box against the Su-35S. The way it bends the top verticals is deadly effective. When you operate in the borders between sustained and instant turn rate that is where things get interesting with this jet.
Sorry that I was not clear, I was answering to the Su-57 video in the post just above mine. The plane moves as it was weightless, it is really amazing. But then, it has more than 80 sqm wing area, without really accounting the supersized, highly optimized lifting body. Empty weight cannot be very high either, seeing how it moves.
But then the problem is that we don’t know empty weights of either Su-57 or Su-35S. So we can argue about wing loading, sustained turn and TWR all that we want, without empty weight data it is all speculation. For instance for the Su-35S you are mentioning, we simply don’t know the weight of the plane. We can speculate it is 18 tons, maybe it is but maybe not, original Flankers were > 16 tons, why would the Su-35S be much heavier? Some equipment was added on top of normal Flanker, some things were removed or optimized (i.e. all that extra fuel must use volume previously occupied with equipment), the air brake was removed too. Aero is not exactly the same as in regular Flankers either. As it is common, Russia makes sure a numerical analysis of their newest aircraft is not easy or certain.
LMFSTruly smooth, the plane really seems to create LOTS of lift, losing very little altitude and speed when turning aerodynamically. By now very little hard maneouvering but rather elegant choreographies, I think we are far from knowing things like what the max sustained turning rate is.
I have said this for years here.. The Russian AF is closer to a HI-HI-HI(-Hi) mix of Flankers/Fullback-Frazor-Foxhound-S70 UAV. See no low mix of Mig-29 in there.
And with that i mean Russia is closer to a new Mig-31 variant over any new medium fighter.
What I meant speaks rather in favour of a new light platform, only not a manned one. The Okhotnik is, despite its relatively heavy weight logical for a strike platform, the “low” (cheaper, disposable) part of the mix, and that is what I think UCAVS will end up doing in the near future. This light A2A platform could support the Su-57 in a proportion of say 2:1 or 4:1 (or even more with the time) for a cheap, fast increase in numbers. A new medium fighter makes no sense to me, as said the MiG-29 was rather a technological compromise than an optimal solution. It is placed at a no-man’s land between a true light fighter and a heavy one, without the clear advantages over the Flankers that would really help the VKS. MiG-35 at least is a reasonable multi-role aircraft and can be sold very well, if it was not because of the stealth hype. Most countries cannot afford to maintain such planes, to start with, so they should stick to what works and is real (IMHO).
So with what is clearly the planned way forward for VKS, they will have a more streamlined supply chain to service a smaller but more inter-connected fleet of jets. A very high range of common spare-parts are used on all Flankers and Fullback. Lets hope they can replace all AL-31F variants with the Idz-117S engine.
This seems to be the case indeed. Engine commonality between Su-30 and 35 has been already confirmed, the work for the Su-34M should be ongoing already (signed very recently) and indeed a more powerful engine with longer life would be a big plus for it, with its 46 t MTOW. Su-33 would benefit massively from the new engine too, but maybe the low numbers and presence of the MiG-29K make the update too expensive and also unnecessary.
What I would be interested in knowing is the true rating of the domestic engines. We know the izd. 117S is essentially an export engine, but we don’t know what izd. 117 can really do and whether it will be used or even is already being used in the Flankers of the VKS.
If it is not already done. All Su-25 regiments should be transfered over to Army Aviation together with their Attack Helios fleet. It just make so much more sense.
It makes even more sense to leave everything “air” to the VKS than having to replicate all those competences, air bases etc in the army.
LMFSAs debated above. the problem is not fielding the Hull of a new DD. Its the propulsion. But keep in mind there is also the Funding. Why do you think Russia keep upgrading their existing fleet to the large point as they have done..
The destroyer would IMO be more of an ABM asset, in case they manage to get S-500 onboard, than a tool to bomb US with CMs. And most probably it will have nuclear propulsion, which is not a problem in Russia from what I know. They need to update Severnoye, that is where they plan to build them.
LMFSThis shows why Russia needs Pr.11441 upgraded Kirov class and (follow it up with) Pr.23560 Lider class cruisers more than ever before. The only solution to US deployment (which the Russians already foresaw) is by having a 24×7 presence off the DC coast with cruise missiles. Nothing else will do.
An answer is already planned, in order to put the “gun” as close to US’s “head” as they are putting it to Russia’s. First, IRBMs close to Bering would have a brief flight covering the whole US Western half, from the nuclear sites to the East to California in the South. Second, Zirkon-loaded SSNs spread around US continental landmass, which would cover all the critical areas in the East Coast too without the need to bother any third country and are all but impossible to locate, given the size of the sea area involved.
LMFSAs they say Perfect is the enemy of Good Enough , Mig-35 is good enough to be competitive for next 25-30 years if bought in numbers it will turn out to be cheaper than all flanker series and less costly to maintain.
The other aspect is UAC and its design bureau is fully loaded with many projects in Civil and Defense. From 20 seater to 400 seater in Civil aircraft and every thing in between and many defense project , Not to mention besides technical man power funding is also an issue.
LMFS is not part of SAP 2018-2027 in any case
I see your point. LMFS is probably dead, but in the next years they need to start thinking about a new platform for sure. If new MiGs are produced they can sure be operational for those 25-30 years you mention, 10-15 of them being still reasonably up to date and the later 10-15 years being increasingly in need of substitution.
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