Su - 57 the Raptor Slayer _ Part 2 - Propulsion
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LearningTranscript
00:00Hello Artis.
00:06I have prepared the specifications for the Su-57 engine, sir.
00:10OK, sure, let's see what you got.
00:12Please cast it on the screen.
00:14Executing.
00:15Yeah, good, good, very good.
00:20Nice job, really nice job.
00:22Where did you get the sources?
00:24I hacked into a NPO Saturn computer.
00:27One of their industrial floor cleaners has a control chip that was assembled on the same
00:31line as mine.
00:45This thing is delicious.
00:46Welcome to Millennium Seven Star, the channel that helps you make sense of military history
00:51and military technology.
00:53This is the second part of the series dedicated to the Sukhoi-57.
00:57If you haven't watched the first part, there will be the link up here.
01:01So in the previous video we have discussed the aerodynamics, the structures and the general
01:06configuration that we've seen, which is very particular, but in this video we will be talking
01:11about propulsion, which is an area where the Sukhoi-57 has a bit of a problem.
01:18The plane is expected to be delivered with the final Isdalia-30 engine only after 2025.
01:25Yeah, but let's start from the beginning.
01:32In 2002, shortly after the beginning of the PAC-FA program, the program that gave birth
01:42to the Sukhoi-57, it was immediately clear that a new generation of engines was required.
01:50At the time, there was a competition between MPO Saturn, the heir of the Lyulka design
01:56bureau, and MPP Salyut, which is the descendant of the Tumansky design bureau.
02:03MPO Saturn won, but almost immediately the design process of the engine was split in
02:09two.
02:10The entirely new generation engine was never going to be ready in time for the first flight.
02:16Designing a new generation of engine is as complex as designing as the whole plane.
02:23So to be ready for a timely first flight, the decision of having a Stage 1 and a Stage
02:292 Sukhoi-57 was taken.
02:32The Stage 1 had to be equipped with an improved version of the already proven AL-31.
02:39The Stage 2 had to be equipped with the final engine, the Izdeliye-30.
02:44So the current engine of the Sukhoi-57 is the AL-41F1.
02:56It has been derived from the engine of the Sukhoi-35, which is called the AL-41F1S, which
03:05is in turn a derivation of the AL-31.
03:10Compared with the original AL-31, it is bigger, it features a digital control unit, and it
03:18provides a lot more thrust.
03:21So the engine provides 93 kN of dry thrust and 147 kN with the afterburner.
03:31However, take these numbers with a pinch of salt because in Russian aerospace, almost
03:38everything is secret.
03:41So some of the key numbers that we have are actually estimates.
03:44Otis please the specifications.
03:47The AL-41F1 is a dual spool, low bypass, afterburning turbofan.
03:53The low pressure compressor has four stages, the high pressure compressor has nine stages.
03:59Each spool has a single stage turbine.
04:02The dry weight is about 1600 kg.
04:06With a dry thrust of 93 kN, the thrust to weight ratio is 5.49.
04:11Thanks Otis.
04:12Well, it is an advanced engine, a powerful one, one of the most advanced in the world,
04:18but is not devoid of problems.
04:21Its ancestor, the AL-31 requires a full overhaul at the factory after about 1000 hours of flight.
04:31Western engines last much longer, I mean four or five times longer.
04:38We may expect the AL-41 to be a bit better, but definitely not radically better.
04:44Furthermore, we have reason to believe that the upgrading actually reduced the reliability
04:52of the engine, which in turn influences the readiness of the aircraft.
04:58This was one of the issues that least allegedly induced the Indians to abandon the joint program
05:05that they were having with Russia.
05:07However, the AL-41 is not destined to be completely dismissed and abandoned, because the export
05:15Suhoi 57, if any, they will be equipped with the AL-41.
05:28Despite the problems and the lack of thrust, actually the AL-41 is not heavily penalizing
05:35for the Suhoi 57.
05:38Coupled with the aircraft outstanding aerodynamics, it is still enough to make the Suhoi 57 the
05:46most maneuverable aircraft ever built.
05:50The intakes are classic wedge intakes with mobile ramps to control the position of the
05:56supersonic shockwaves, and they are obviously very efficient at transonic and supersonic speed.
06:03The conduit section is in irregular loads to improve the stealthiness and the radar
06:11reflection characteristics.
06:14Like on most Russian planes, retractable grids are used at takeoff to avoid ingestion on
06:21foreign object debris.
06:23A different grid is used to increase stealthiness by protecting and screening the compressor
06:31blades just before the engine entrance.
06:36A similar screening element is added downstream the turbine.
06:41And before someone starts screaming that the Russians don't really know what they are doing,
06:45they don't have any clue about stealthiness, this is the same solution which is used on
06:52the F-18, that was used on the F-117, and even the F-35 and the F-22 have an element
07:00to screen the turbine.
07:03And last but not least, the engine features thrust vectoring.
07:08We will get back to thrust vectoring in the last section of the video, but for now let's
07:13say that it is commonly believed that the nozzles move up and down basically in a sort
07:19of a V pattern.
07:21For the Suhoi 57 we have the reason to believe that they move 360 degrees differentially
07:27and they are controlled by the flight computer.
07:30And this is probably the secret of the plane's bizarre manoeuvrability.
07:40The Product 30 is going to be the final engine for the Suhoi 57.
07:45It has flown for the first time in 2017 and it is currently undergoing testing.
07:53The first Su-57 equipped with the Product 30 is expected to enter production in 2025.
08:01Now NPO Saturn really made a leap forward with this engine.
08:07It will be a modern variable bypass ratio turbofan, it will feature a full authority
08:14digital control unit connected with the flight computer, it will have a modern plasma igniter,
08:22and last but not least it will feature a new lighter thrust vectoring nozzle with serrated panels.
08:30The dry thrust is expected to be 108kN and the afterburner thrust 176kN.
08:40Russian engines tend to be on the heavy side because, well, Russian engineering I suppose,
08:46but also because the thrust vectoring engine is actually quite heavy normally.
08:52The Product 30 has changed all this and the thrust to weight ratio with afterburner is
08:58expected to be around 11, which is pretty much in the same ballpark as the F-35 engine.
09:05And for those who always love to point out that Russia is so way behind the United States
09:12in terms of technology, well, this time you are right, Russia is probably 10 to 15 years behind.
09:19However, the entry temperature in turbine, which is a very important parameter to qualify the efficiency
09:28and performance of the engine, is expected to be a bit above the psychological barrier of the 2000K.
09:38This will make the Product 30 the hottest engine in the world, even hotter than the F-35 engine.
09:46Yevgeny Marchukov, the Lyulka chief designer, is convinced that the combination of variable bypass and plasma igniter
09:55will make the Product 30 less thirsty than the AL-41.
10:02It may be interesting to notice that if these numbers are true, even at maximum take-off weight,
10:17the thrust to weight ratio for the Su-57 will be significantly above 1.
10:24And if the thrust to weight ratio will be high, this means short take-off and very good acceleration.
10:32Actually, short take-off is a very important feature for the Russians.
10:37They do expect that air bases are going to be attacked in case of war, so it becomes important that the aircraft
10:45can use the shorter strips that still remain intact to take-off.
10:50Moreover, such a high thrust to weight ratio would be very useful for a carrier variant, should one be developed.
10:59The Su-57 is obviously supercruise capable.
11:03With the AL-41 the reported supercruise speed is Mach 1.1 or Mach 1.2,
11:12but with the Product 30 it is expected to reach Mach 1.4-1.5.
11:19As usual, take this with a pinch of salt.
11:22However, we have seen in another video how supercruise is a very important feature,
11:26because it greatly improves the range and the energy of the air-to-air weapons, particularly at very long range.
11:36And finally, the elephant on the tail, thrust vectoring.
11:49Well, obviously this is a controversial and misunderstood feature, and it would deserve a video in itself,
11:57which we actually did some time ago, and the link will be up here.
12:02The consensus is that thrust vectoring is of limited use, and in general similar performances can be reached
12:12with the correct design of the aerodynamic surfaces.
12:16The Americans investigated this concept quite extensively, and this was their conclusion.
12:22So the F-22 has a simplified thrust vectoring, the F-35 has none, and no European project actually features it.
12:31And when the United States Air Force could test the Flanker on their own terms at the end of the Cold War,
12:38they had their view confirmed.
12:41Furthermore, members of the Indian Air Force, who fly the Sukhoi-30MKI, which actually features thrust vectoring,
12:51they declared that it is used as a sort of last resort to increase the pitch of the plane and increase the instantaneous turn rate.
13:03This will be used to point the nose at the opponent, but if the maneuver fails to shut down the enemy,
13:11then the aircraft is left very very vulnerable.
13:15There is an interesting video on YouTube of an F-18 Super Hornet fighting against a Su-30MKM of the Malaysian Air Force,
13:26and defeating it repeatedly, despite the use of thrust vectoring.
13:32So, case closed?
13:34Well, we are left with two possibilities.
13:38One, the Russians are a bunch of idiots who spend money and add complexity and weight to their top-of-the-line fighters just to add a useless feature.
13:49Two, the Russians know something that we don't know, or at least they plan to do something that we don't know where thrust vectoring has a role.
14:00Now, I wish I had an answer, but I don't.
14:04What I have are a couple of considerations and a couple of hypotheses.
14:10The first consideration is that there is still a vast underestimation of Russian technology in the West.
14:19This is a legacy of the Cold War.
14:22In fact, the gap has never been as wide as it was perceived, and in the last 30 years, the same gap has narrowed quite a lot.
14:32Today, there are reports of the American intelligence where they clearly state that the Russians are ahead in a number of key technologies.
14:43This could be the subject of an entire long video, but what matters the most is understanding that Russia has radically changed the doctrine that they are using from the Soviet one.
14:55They have learned lessons from the wars in the Middle East too, but what they are doing is not trying to imitate the West.
15:04They are always trying to build some level of asymmetry in their doctrine and in their tactics.
15:11The second consideration is that no Russian system designed for export has the same feature of the systems in service domestically.
15:21This is a common practice in Russian industry, and some level of downgrading is always applied.
15:27So, there is a small but real possibility that should a confrontation with Russia erupt,
15:36the systems that the West is going to face are not exactly the same systems that has been faced in these years around the world.
15:47Ok, within this context, we can make two hypotheses.
15:54The first hypothesis is that truss vectoring is implemented for flight efficiency reasons.
16:01It is in principle possible to trim the plane not using the aerodynamic surfaces, not deflecting the aerodynamic surfaces, but orienting the engine thrust.
16:16Why would you do that? Because in this way you could keep your aerodynamic surfaces at the lowest drag possible compatible with the flight.
16:26An effect like this is probably small, but surely not negligible, and there is the possibility that something like this has been implemented.
16:38Mind, this is speculation, we have no specific news about it.
16:42Another hypothesis revolves around the idea that truss vectoring allows unconventional maneuvers.
16:50For example, using truss vectoring with a very quick deflection is possible to give the plane a jerk, so to speak, sideways, that changes the flight path, changes the speed and acceleration vectors of the plane.
17:04It would be a sort of instantaneous maneuver.
17:07Why this would be important?
17:09Well, modern air-to-air missiles use guidance criteria, which in general tend to predict or anticipate the point of impact.
17:21The missile is not chasing the plane, the missile is trying to anticipate the impact because, well, it's much more efficient.
17:30Now, the digital filters used on the missiles have to make a prediction, and the prediction is normally based on speed and acceleration of the target.
17:43If the acceleration of the target is somehow unusual, there is the possibility that the algorithm gets confused.
17:54In which measure this is going to affect the weapon?
17:58It's very difficult to say, it's probably not going to throw the weapon totally off course, but could make the interception trajectory less efficient.
18:10Again, this is just maybe, this is just my speculation, but that would be really interesting to know.
18:17Bottom line is, I think we had better not dismissing this feature as irrelevant or useless.
18:24That's all for now, thank you very much for watching, and see you the next time.