Sukhoi Su-57

[JasonJ]

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Edited April 4, 2019 by JasonJ

[KV7]

Thanks, this is v. helpful.

[GARGEAN]

Is it possible to relocate old posts about it here?

[KV7]

Reposting this ok, if a little rosy and hyperbolic article:

http://fullafterburner.weebly.com/aerospace/sukhoi-pak-fa-the-anti-stealth-gamechanger

[Loopycrank]

The bits about the sensor suite being "anti-stealth" are arrant nonsense. IRSTs are not particularly capable and easy to counter, and the reasons why have been explained at length by people who understand atmospheric transmission windows and peak emission spectra to people who dislike thinking. Likewise, the reason why fighter-mounted L band radar is ridiculous has been patiently explained by people who understand radar physics to those who do not, and those who do not predictably plugged their ears and started gargling. The bit about the Indian FGFA being a substantially different aircraft is, to my understanding, largely obsolete. The Russian and Indian versions of the aircraft will be essentially the same, mainly because Indian industry couldn't get its act together. Otherwise, it's not a bad article.

 

Think of the SU-57 as a bigger, probably faster F-35A and you're not far of the mark.

[Simon Tan]

More like a YF23?

[GARGEAN]

Lol. Bigger and PROBABLY(that's good part) faster F-35. Yeeeeah... Disregarding 8 radar antennas with 360 degree coverage instead of one, MUCH better speed and all-overall agility even with current engines, DLIRCM, wider weapons choice(albeit indeed with some vacancy unoccupied by now)... And some other interesting stuff that is too speculative to tell for now. But alas, I'm just a fanboi who only rad some magazines about F-22 and T-50 is(geniunely) not a production aircraft for now.

Oh, BTW, FGFA is not a thing for now.

[Loopycrank]

Disregarding 8 radar antennas with 360 degree coverage instead of one,

 

Yes, because that idea is nonsense. We know that the SU-57 has a central nose radar and two cheek arrays. Where are these other putative arrays supposed to even be on the aircraft?

 

There are AESA arrays in the leading edges of the wing, behind the slats, yes, but those aren't radars. At least not primarily. They couldn't be; they operate in too long of a wavelength and they are simply too small to have adequate resolution. Those wing arrays are LPI IFF, with a secondary role as jammers.

 

The tailcone? Maybe there's a radar back there, but what exactly would it do? Again, radars are sized they way they are sized because of fundamental constraints of physics. Anything that small is going to have poor range, poor resolution, or both. The only thing it would be useful for is a MAWS, but that seems unlikely because we already know that the SU-57 has a UV-based MAWS with distributed, hexagonal apertures all over the airframe.

 

Any phased array RF emitter on the SU-57 that isn't the main nose radar or the cheek arrays is probably a jammer first and foremost. They're too small to be very useful radars. I concede that if they are all AESA then it wouldn't be terribly hard to use them as radars if the need arose, but what could they possibly be useful for?

 

MUCH better speed and all-overall agility even with current engines,

 

I think that the SU-57 is faster than the F-35 because it has variable geometry air intakes. Those aren't really a net positive until around mach 2.0, so it seems reasonable to surmise that the SU-57's top dash speed is somewhere north of that.

 

But better overall agility? Really? Tell me how you determined that. I suppose that you have access to TsAGI wind tunnel test results so you know all the details of the drag polar of the SU-57. On top of that I suppose that you spoke with NPO Saturn and they helpfully provided you with a chart of the dynamic thrust and pressure recovery of the engine/intake combination. And, needless to say, you also are privy to all the flight testing documents and know what the maximum AOA is as well as what the exact gross weight of the aircraft is with a combat load.

 

I further assume that you have the equivalent information on hand for the F-35.

 

Because that is the information you would need to draw up a set of E-M diagrams for the aircraft, and that is the bare minimum of information you would need in order for that statement to have any meaning.

[GARGEAN]

Just as I said, I'm just a poor lil fanboi who knows nothing. Yeah...

[KV7]

Well that escalated quickly.

[GARGEAN]

Well that escalated quickly.

Not really) Exact at level that was expected from the very beginning of topic. Just wait till "steel marble" argument...

[Josh]

The cheek and rear mounted radars do seem a little odd. They could only be effective against 4th gen type targets at pretty close ranges, like WVR, and against a 5th gen it seems they would be useless. The jammer explanation does make more sense, perhaps with a secondary detection capability for missiles and aircraft that get behind the fighter. Basically fulfilling the role of DAS on F-35, only with an active emitter.

 

It seems very safe to assume top speed is higher than F-35, but the more interesting question to me is what its top speed at full military power is. I think its pretty safe to say with 3D thrust vectoring that it will out maneuver an an F-35 in most respects, despite being a much larger aircraft. There's no way to know that, but it seems like a safe bet to me. The question to me would be whether that's truly useful in modern WVR with 180° HOBS 60G+ IIR missiles.

 

Perhaps we'll learn more when the aircraft enters production and shows up at a couple air shows. I'm curious how willing they will be to sell their best aircraft tech, though obviously the Indians area already getting it so chances are they are willing to hock it pretty far and wide.

[GARGEAN]

The cheek and rear mounted radars do seem a little odd. They could only be effective against 4th gen type targets at pretty close ranges, like WVR, and against a 5th gen it seems they would be useless. The jammer explanation does make more sense, perhaps with a secondary detection capability for missiles and aircraft that get behind the fighter. Basically fulfilling the role of DAS on F-35, only with an active emitter.

 

It seems very safe to assume top speed is higher than F-35, but the more interesting question to me is what its top speed at full military power is. I think its pretty safe to say with 3D thrust vectoring that it will out maneuver an an F-35 in most respects, despite being a much larger aircraft. There's no way to know that, but it seems like a safe bet to me. The question to me would be whether that's truly useful in modern WVR with 180° HOBS 60G+ IIR missiles.

 

Perhaps we'll learn more when the aircraft enters production and shows up at a couple air shows. I'm curious how willing they will be to sell their best aircraft tech, though obviously the Indians area already getting it so chances are they are willing to hock it pretty far and wide.

All-aspect radar coverage is always more preferrer to only forward-aspect. Even with "weak" (some poor 150km against 400km range) side and rear looking radars. Just one example - self-designating for AAMs in 360 deg area. Which is VERY useful. Also one should not forget efficiency loss at beam steering angles of any fixed AESA radar. Thus smol radar at its 30 degrees can be not much worse that big one at its 60 degrees. Plus powerful direct jamming capability... As for AAAM work - T-50 already have set of passive sensors with DLIRCM on top of them. So radars here are just to supplement it and to add more effective work against radar-homing AAMs.

 

And that one is by far interesting question) Some details gives different results from analysis, like most fuselage being optimised for 2.35-2.5M range and intakes being engineered to work on up to 3M speeds. In any case variable intakes, goot T/W ratio and silicate dome indicates that it should be FAST and more of it - optimized to long top-speed flights, unlike other fast but poor heat-resisting aircrafts like T-10 or F-15. And nope, maneuverability is not only useful in WVR with those pesky SRAAMs. In any case it was achieved without some great sacrifices in other areas, so why not?

 

And no, as I said - FGFA or any other indian version is not a thing for not, so they are not "already getting it". They wanted full tech transfer with first delivery of planes for some laughtful money(less that they gave for 36 Rafales). In the end nothing farther than evaluation contract(at couple hundreds millions) was made, FGFA wasn't modelled and India lost its opportunity to fund part of development and get some benefits from it.

 

As for sales abroad in whole... Well, those high-sitting dumbasses was very generous at selling top-end stuff abroad, even to those who should't get it in any case, so selling T-50 would be only question of production capacity(already growing) and ability of buyer to pay(not hard cap too, look at Indonesian Su-35).

[Josh]

What is the current Indian position then? Didn't they sink a lot of development funding into the aircraft already?

[GARGEAN]

What is the current Indian position then? Didn't they sink a lot of development funding into the aircraft already?

They sink zero point zero in development of aircraft. There were only one initial "research" contract about sketch of indian version of aircraft based on T-50. That was for, IIRC, 180 millions. Development of T-50 is fully indigenous. As for now... Well, indians are bitching. As usual. There are one contract after another, and none of them was singed. Indian version is aircraft is "so muh bad", real world is they want full tech transfer which is not on russian mind. Especially now, when development in whole is finished already.

[Loopycrank]

I think its pretty safe to say with 3D thrust vectoring that it will out maneuver an an F-35 in most respects, despite being a much larger aircraft. There's no way to know that, but it seems like a safe bet to me. The question to me would be whether that's truly useful in modern WVR with 180° HOBS 60G+ IIR missiles.

 

Thrust vectoring doesn't improve maneuverability that much in fighters. In missiles it is a game changer, but in fighters, not really.

 

A fighter aircraft is going to have a thrust to weight ratio slightly in excess of 1:1 under combat conditions, optimistically. This means that the total force that the thrust vectoring can produce will be the sine of the maximum vector angle times the thrust. And that's assuming that there's no thrust loss from vectoring to such an extreme angle, and usually there is some.

 

For a twenty degree vector nozzle and a TWR a bit better than unity you're looking a .4 Gs of acceleration perpendicular to the normal thrust line from thrust vectoring. .4 Gs isn't particularly awe-inspiring when you consider that the wings are capable of producing up to 9 Gs of acceleration along the Y axis of the aircraft when the aircraft is in the best part of its maneuvering envelope. That and the aircraft is giving up a full 7% of its forward thrust to do this, which is eating into its sustained turn rate.

 

Airfoils are a better way to generate lift than engines, which is why planes have wings instead of a second set of engines pointing down. It's generally more effective to generate lift and torque with airfoils than it is with engine thrust.

 

The exceptions are when the airfoils are not up to the task of generating lift. If the aircraft is moving slowly, or if the air is of very low density or if the main wing is stalled, then thrust vectoring will become a useful addition. So, during takeoff and landing, high altitude operation and very slow speed and post-stall maneuvering thrust vectoring is quite useful.

 

Thrust vectoring improves fighter flight performance at the edges of the performance envelope, but does fairly little for agility in the more optimal regions of the flight envelope.

 

For missiles it's different because they have very high thrust to weight ratios and tiny airfoils.

[KV7]

Why do we not see any proposals for deeply concealed nozzles on any stealth fighter platforms - as on B-2 and YF-23 ?

Edited February 6, 2018 by KV7

[GARGEAN]

Why do we not see any proposals for deeply concealed nozzles on any stealth fighter platforms - as on B-2 and YF-23 ?

Rear-aspect stealth is not priority in most cases and doing magic with nozzles is doing to screw with thrust(like in case with F-22, where not enev truly flat nozzles are eating up to 10% of thrust).

[JW Collins]

Where do you get that 10% figure from? I can't envision the Su-57 doing much over Mach 2.5 for the same reason the F-15 maxes out there.

 

F-35 will still be a very tough challenge for it but the existence of this and the Chinese 5th gen designs is proof of the stupidity of ceasing F-22 production.

[GARGEAN]

Where do you get that 10% figure from? I can't envision the Su-57 doing much over Mach 2.5 for the same reason the F-15 maxes out there.

 

F-35 will still be a very tough challenge for it but the existence of this and the Chinese 5th gen designs is proof of the stupidity of ceasing F-22 production.

Chinese 5th gen is Lego toy for now. 10% is maxed at tilt regimes, with straight positioned nozzle it would be around 7-8%.

Also noone said that T-50 would go much over M2.5. Most posdible is M2.3 for sustained flight. As for F-15 - compare its materials(esp capony) with those of T-50.

[Yama]

The cheek and rear mounted radars do seem a little odd. They could only be effective against 4th gen type targets at pretty close ranges, like WVR, and against a 5th gen it seems they would be useless. The jammer explanation does make more sense, perhaps with a secondary detection capability for missiles and aircraft that get behind the fighter. Basically fulfilling the role of DAS on F-35, only with an active emitter.

One of main purposes of the cheek arrays is to expand coverage of the main forward array. Phased array radars give their full range only straight ahead, steering the beam off from centre axis costs them range. This in contrast to mechanically steered antennas, which can employ their full range over much wider area.

One solution for this is to make mechanically steered phased array, this is used in for example Eurofighter and Su-35. Another is to add more arrays which can be combined with main array to produce more powerful off-axis beams. F-22 was supposed to have cheek arrays but they were cut for cost reasons.

 

Also, modern AESA radars are no longer so much 'radars' as part of the multipurpose electromagnetic sensor/emitter system. They can be used to enhance EW and IFF capabilities, and to some extent act as missile approach warning sensors.

[Josh]

F-35 will still be a very tough challenge for it but the existence of this and the Chinese 5th gen designs is proof of the stupidity of ceasing F-22 production.

There likely will be more F-22 produced than Su-57. Even Russian sources indicate fairly modest numbers of aircraft in the low hundreds, with one mention being as low as 150, and that's from the vaporware capital of the world. Unless oil spirals upwards, which even with Venezuela falling apart seems unlikely given US production, the Su-57 fleet is going to be limited.

 

The other issue is basing - particularly against China. Just where were you going to base all the F-22s in a Sino American war? There are several US bases in Japan or Korea that are well with in short range BM range and Anderson. That's about it. I'm not sure the US could deploy more wings forward than it has in case of war with either Russia or China, though I suppose a war with both would stretch the fleet.

[lastdingo]

The Chinese "5th gen" fighters are not going to reach Hawaii in anything but very rare stunts, so they are no threat to the United States.

 

If anything, their existence points at the stupidity of outlawing F-22 export to Japan and not providing Taiwan and South Korea with much better air defence systems (which the USAF itself doesn't have itself).

 

I oppose the tone that implies that the U.S. has to be involved in East Asian wars of the future. It doesn't need to be involved. Alliances are supposed to benefit all members, and the U.S. is not being threatened in East Asia. Guam is negligible. It could be demilitarised like the East Aegean and would not be one iota less safe (it's rather indefensible anyway).

[Josh]

The US has defense obligations with several different nations in the Western Pacific, therefore it needs to be able to fight a war in the Western Pacific. If Taiwan, Japan, Korea, and the Philippines declare that all Yanquis must go home, well then that's that then. But until that day, that is where a war between the US and China will be fought.

[lastdingo]

The US has defense obligations with several different nations in the Western Pacific,

 

That's a choice, and it can be changed.

 

This is weird about modern alliances; people pretend that they're eternal and kind of law of nature. Same with NATO.

Gone the times of changing alliances (save for maybe Turkey) - heck, Italians even changed sides during both world wars!

To treat non-self evident things as self-evident may lead to very stupid policies.

 

U.S: and PRC do not need to be rivals or opposing each other, and the U.S. doesn't need to prepare for war against the PRC.

It's all about choices.

Edited February 6, 2018 by lastdingo