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SU-57 T-50 Russia Sukhoi flying pancake India

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#1 JasonJ

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Posted 28 January 2018 - 2340 PM

SU-57.jpg

 

Gentlemen, some interesting discussion about its stealthiness and such happened in different threads and it would be a shame for the discussion to become difficult to track down with the passing of time and it is unlikely that all those details would voluntarily be made again by the posters. So just to link to it starting around here and going for a couple of pages. In addition to that, any other interesting bits such as regarding  the program with India and such would be interesting to see here as well. I have spent some attention on the development of the J-20 so a recount on the history of the T-50 development history would also be interesting IMO.


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#2 KV7

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Posted 29 January 2018 - 0034 AM

Thanks, this is v. helpful.


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#3 GARGEAN

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Posted 29 January 2018 - 0106 AM

Is it possible to relocate old posts about it here?
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#4 KV7

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Posted 29 January 2018 - 1015 AM

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

http://fullafterburn...lth-gamechanger


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#5 Loopycrank

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Posted 29 January 2018 - 1129 AM

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.


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#6 Simon Tan

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Posted 29 January 2018 - 1319 PM

More like a YF23?
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#7 GARGEAN

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Posted 29 January 2018 - 1349 PM

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. 


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#8 Loopycrank

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Posted 30 January 2018 - 0033 AM

 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.


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#9 GARGEAN

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Posted 30 January 2018 - 0116 AM

Just as I said, I'm just a poor lil fanboi who knows nothing. Yeah...
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#10 KV7

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Posted 30 January 2018 - 0529 AM

Well that escalated quickly.


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#11 GARGEAN

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Posted 30 January 2018 - 0553 AM

Well that escalated quickly.

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

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Posted 30 January 2018 - 0911 AM

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.
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#13 GARGEAN

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Posted 30 January 2018 - 1028 AM

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).


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#14 Josh

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Posted 30 January 2018 - 1054 AM

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

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Posted 30 January 2018 - 1058 AM

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.


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#16 Loopycrank

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Posted 30 January 2018 - 1321 PM

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.


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#17 KV7

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Posted 05 February 2018 - 2311 PM

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


Edited by KV7, 05 February 2018 - 2311 PM.

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#18 GARGEAN

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Posted 06 February 2018 - 0117 AM

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).
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#19 JW Collins

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Posted 06 February 2018 - 0406 AM

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.
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#20 GARGEAN

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Posted 06 February 2018 - 0430 AM

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.
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