Su-57 Stealth Fighter: News #6

Su-27 is around 15m2. Su-57 according to sukhoi is 0.1-1m2 (best-worst cases I think).

Su-57 is like 100 times stealthier than su-27.

Isos wrote:Su-27 is around 15m2. Su-57 according to sukhoi is 0.1-1m2 (best-worst cases I think).

Su-57 is like 100 times stealthier than su-27.

0.1-1m2 - these are the average values for the entire construction type. This does not mean that the best indicator for the su-57 is only 0.1 m2.

Scorpius wrote:

Isos wrote:Su-27 is around 15m2. Su-57 according to sukhoi is 0.1-1m2 (best-worst cases I think).

Su-57 is like 100 times stealthier than su-27.

0.1-1m2 - these are the average values for the entire construction type. This does not mean that the best indicator for the su-57 is only 0.1 m2.

That's what counts. The aircraft would move in the air and will never be in the perfect conditions as when they measured the best rcs.

0.1 is perfect. And it doesn't have weapons to increase it under the wings.

Arrow wrote:So it looks like the F-135 is the most advanced military aircraft engine in the world. At least until we know the performance of izd 30.

Yes of course, at least if the claimed values are true. TWR is above 11, TIT is 3600F, OPR is 28... values head and shoulders above any comparable engine. As you say we need to see what izd. 30 brings, in the end AL-41F1 is not really a new design but an AL-31 variant.

US are the most advanced in aircraft engines. They are leaders in that field and they have lot of money from civilian engines.

Russia is recovering from USSR death.

EU are too stupid to launch a europen company to produce engines for airbus and let the big piece of cake to US and UK.

JohninMK wrote:Having to run the F-135 at those temperatures sure produces an interesting hot air plume behind it. Surely a major problem in an IR world, negating much of the 'stealth' features?

That's true for any aircraft.

IR signature can't be really hidden. Their engines heat a lot and modern IR cameras/sensors are very good and getting better every year.

Unfortunately it doesn't seem like they would be able to deliver the first production Su-57 this year. Bummer that. Was really looking forward to it.

JohninMK wrote:Having to run the F-135 at those temperatures sure produces an interesting hot air plume behind it. Surely a major problem in an IR world, negating much of the 'stealth' features?

Sure, but they have some countermeasures like a cooled blocker inside of the nozzle and a layer of could air surrounding the exterior. Despite the increased risk of detection, temperature is one of the few ways you can increase the efficiency and thrust of an engine so it is the way to go.

Nice picture but what impresses me is the flat terrain behind. S-400 woukd be happy to sit there and kornet would be usefull at very long range.

On the su 57 RCS vs F-22 or F-35
The original tender by the USSR for the 5th gen aircraft called for capability parity with the F-22. Which makes sense because parity with the US has been USSR/Russia military doctrine since Stalin.

Sure the F-22 is more stealthy from the back and all that. But generally , the su 57 isn't going to be any less stealth than the F series. Unless you think Sukhoi knowingly stopped short of fulfilling the requirements of the tender which also makes Russia in violation of its most basic military doctrine.

But there are still morons online who think the F-22 is multiple standard deviations more stealth than the su 57 because some airforce jock told the Discovery channel that the F-22 is the size of a golf ball on radar. Which they convert to 0.000000000001 RCS

Backman wrote:On the su 57 RCS vs F-22 or F-35
The original tender by the USSR for the 5th gen aircraft called for capability parity with the F-22. Which makes sense because parity with the US has been USSR/Russia military doctrine since Stalin.

Sure the F-22 is more stealthy from the back and all that. But generally , the su 57 isn't going to be any less stealth than the F series. Unless you think Sukhoi knowingly stop short of fulfilling the requirements of the tender which also makes Russia in violation of its most basic military doctrine.

But there are still morons online who think the F-22 is multiple standard deviations more stealth than the su 57 because some airforce jock told the Discovery channel that the F-22 is the size of a golf ball on radar. Which they convert to 0.000000000001 RCS

F-22 has pretty big RCS. Same as F-15 if not bigger. If you want small RCS go for a small plastic drone like TB2. It's virtually undetectable by radar.

That's true for any aircraft.

IR signature can't be really hidden. Their engines heat a lot and modern IR cameras/sensors are very good and getting better every year.

A turbojet makes the air flowing through it very hot but a turbofan has air flowing through the hot section but also cold air that bypasses the hot section so it blows higher density cold air as well as hot air which mixes in the exhaust and creates a large volume of moving airflow which = thrust.

When a turbofan uses afterburner the cold dense air is oxygen rich and you can dump more fuel in the exhaust in the AB to create rather more thrust than a turbojet.

If you want small RCS go for a small plastic drone like TB2. It's virtually undetectable by radar.

Hahahaha... the plastic surface might not reflect radar, but radar waves go right through and what sort of radar cross section do you think your average engine has with all its bumps and curves... it is tiny hand held drones that use batteries and electric motors that are hard to detect with radar... big drones like TB2 are only hard to spot by air forces like NK or a broken country like Libya.

In most normal countries a TB2 would be detected easily and even a MiG-21 or Su-17 could chase it down and shoot it down.

Smaller drones would be much harder to find and engage.

Any aperture where an antenna is placed needs to be radio transparent at that frequency, in the case of the main radar that is like 1 sqm full with metal reflectors, plus all the ECM/ESM and communications apertures, plus all the gaps and access panels, plus all the LE, plus cockpit plus the intakes, plus... and they say it all has the reflective surface of a marble? Sure...

Some plonkers on Twitter were bringing up the alleged issues with the su 57 canopy again. Because the su 57 has a canopy pillar and the F-22 doesn't. And neither does the J-20, they've concocted this idea that pillar= bad.

Funny that. Here is the YF-23 canopy. The same YF-23 that had better all aspect stealth than the F-22.

Same complaints about older Soviet fighters but mostly from ignorance.

A canopy is not just clear material you see the world through while flying an aircraft.

A canopy has to be strong enough to withstand impacts with large birds, but also be thin enough to see through easily.

The two section canopy of the Su-57 has a front section that will be very strong to withstand impacts on takeoff and landing with birds, while the main transparency can be made thinner and easier to see through.

The one piece canopy of say an F-16 needs to be thick which makes it fantastic to look through, but it also makes it heavy... if you make the front thicker and stronger to resist impacts and the rest thinner so it is easier to see through then you get distortions and the wrong impression of where things are... like looking into water bends light so the fish is not where it appears to be.

The fact of the matter even a fully strapped in pilot can move their head up and down quite a distance so anything behind the structure can be revealed simply by bobbing ones head occasionally... of course the structure blocking the pilots view is well within the field of view of the nose mounted radar and IRST so even if a target managed to get into that tiny blind spot it will still be detected and tracked so the problem is really only a problem for some people...

LMFS wrote:No worries, we all answer when we can, if we can  

Again, sorry for the late replay, I was few days on the field hunting with the birds of prey!

LMFS wrote:I see no problem, see the "static stability" part in the text you quote. In general I am making no assumptions as to how much lift the canard generates at a given speed, altitude, load etc. in the Eurofighter. My point is that canard is creating a positive contribution to lift instead of a negative one.

Exactly, but my point on the other hand was that at certain conditions positive canard deflection can have negative impact on the main wing thus reducing the overall lift.

LMFS wrote:@GarryB, @PeregrineFalcon:

the guy linked by zepia keeps delivering, watch this about the foreplanes:

https://www.youtube.com/watch?v=Ny0NjjjJqaA

Very nice chanel, although the video you linked is not very helpful for our discussion [yours and mine], his other video actually is  



Look at 11:15

LMFS wrote:You have a point there, I had not fully realized the plane of the canards is higher than the wing but the tips are quite low, I wonder why this very marked anhedral angle... maybe for roll stability reasons?

I don't think they had stability on their mind because anhedral angle is used for the opposite reason [unlike dihedral angle], but maybe they wanted to direct canard vortex closer to the main wing when the plane is at higher AoA for increased maneuverability. If the canard tips vere at the same plane as the canard root, the vortex interaction with the main wing would most probably be absent at desired level.
When the flow above the main wing has begun to experience turbulence, the vortex core from the canard will hit the flow above the wing and make it re-streamline.

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I will have to point out that this is just my theory that can be wrong?!

Anyway, I think that the PAK FA solution is the most "elegant" one regarding performance and also RCS!

I like how the Millennium 7 guy is having none of this nonsense about the su 57 not being LO enough. He casually uses both the F-22 and su 57 when he's explaining stuff about stealth. Like the intakes for example.