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Sukhoi Su-57 / T-50 / PAK FA - flight testing and development Part II

overscan (PaulMM)

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If I understand the patent correctly rather the device is of some length and the visible part is the leading edge and its purpose is to introduce multiple bounces into the radar path to and from the engine face to attenuate the signal. By reducing the duct into multiple smaller sections the number of bounces is greatly increased.
 

Sundog

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That's a weird one. Looks more like a device for flow control rather than a blocker.
It would actually function as both, just due to the nature of the flow going through the blocker. The problem is, you can only see the front face of it. You can almost see some curvature in the wall of the small section at the bottom, the sort of miniature s-duct forming. I was actually more interested in the fixed oblique ramps that are in the sides of the inlets now.
 

stealthflanker

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Guess the "real" blocker is behind it. Or maybe that's where the blocker would be attached, ahead of it. The blocker would be at front while that device "straighten" any flow distortion caused by the blocker to provide the engine the air it needs.

Or maybe yes it's the blocker itself, consulting from this patent image

 

Nortrop

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The radar blocker looks quite low loss. I wonder how this system compares to a S-duct.
The S-channel has never been the ideal solution for RCS reduction. This is the simplest solution. Engineers from Northrop and Boeing are not idiots and have relied on blockers. The level of RCS X-32 and YF-23 fully met the requirements of the military. The nonsense about the mandatory use of S-channels on stealth aircraft was invented by stupid and uneducated people.
 

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Ronny

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The S-channel has never been the ideal solution for RCS reduction. This is the simplest solution. Engineers from Northrop and Boeing are not idiots and have relied on blockers. The level of RCS X-32 and YF-23 fully met the requirements of the military. The nonsense about the mandatory use of S-channels on stealth aircraft was invented by stupid and uneducated people.
S-channel is not the simplest solution, it is the most effective way to reduce radar signature in the inlet because the shape and length of an S-duct make radar wave bounce of the wall many times before they can coming out of the duct, the longer the duct and the more curvy it is, the more bounce you will have, and as a result, the bigger accumulated radar absorbing capability. A layer of RAM with modest absorbing capability of 5-15 dB can be accumulated to 60 dB even with a slight curved duct. ( 60 dB mean you reduce radar wave power by 1.000.000 times). But an S-channel is lot heavier than a blocker and it can take up valuable space for fuel and weapon bay



Secondly, when radar wave strike an edge, they will be diffracted, this diffraction effect can cause radar wave to scattered in many directions including straight back, the more edges there are, the more diffraction, an inlet blocker has a lot more edges than an S-duct because an S-duct only has the edge on the inlet lips




YF-23 use an S-duct and the F-23 mock up that was used in RCS measurement is F-23EMD which has an additional DSI
F-23 RCS mockup side 623.jpg
F-23A EMD dwg 623.gif
 
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Nortrop

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The S-channel has never been the ideal solution for RCS reduction. This is the simplest solution. Engineers from Northrop and Boeing are not idiots and have relied on blockers. The level of RCS X-32 and YF-23 fully met the requirements of the military. The nonsense about the mandatory use of S-channels on stealth aircraft was invented by stupid and uneducated people.
S-channel is not the simplest solution, it is the most effective way to reduce radar signature in the inlet because the shape and length of an S-duct make radar wave bounce of the wall many times before they can coming out of the duct, the longer the duct and the more curvy it is, the more bounce you will have, and as a result, the bigger accumulated radar absorbing capability. A layer of RAM with modest absorbing capability of 5-15 dB can be accumulated to 60 dB even with a slight curved duct. ( 60 dB mean you reduce radar wave power by 1.000.000 times). But an S-channel is lot heavier than a blocker and it can take up valuable space for fuel and weapon bay



Secondly, when radar wave strike an edge, they will be diffracted, this diffraction effect can cause radar wave to scattered in many directions including straight back, the more edges there are, the more diffraction, an inlet blocker has a lot more edges than an S-duct because an S-duct only has the edge on the inlet lips




YF-23 use an S-duct and the F-23 mock up that was used in RCS measurement is F-23EMD which has an additional DSI
View attachment 645862
View attachment 645863

S-channel is the simplest solution. In YF-23 this is not fully implemented. The X-32 doesn't have one at all. The aircraft fully satisfied the military in terms of RCS. At the same time, it was built 10 years after the YF-23 and F-22. Diffracted is absent when using a composite blocker. Engineers from Boeing are not idiots.
 
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TSARb

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S-shaping is the best way to achieve extreme low observability of inlet, because a blocker (even made of RAMs) have it's own radar' reflection too. But that reflection is negligible compared to other parts of LO fighter, like radars, lots of other antennas, surface itself, leading edges of the wing, tails, etc.
 
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Ronny

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S-channel is the simplest solution. In YF-23 this is not fully implemented. The X-32 doesn't have one at all. The aircraft fully satisfied the military in terms of RCS. At the same time, it was built 10 years after the YF-23 and F-22.Engineers from Boeing are not idiots.
S- channel isn't the simplest solution, it just the most efficient from signature point of view because it cause the signal to bounce multiple time and accumulate the radar absorbing effect of the RAM layer. Engine face blocker was first used on F-117 ways before S-duct were designed and used on F-22 and F-35. Engine blocker also used on F-18 E/F
YF-23 and F-23EMD both used S-duct, but the one used for RCS evaluation is F-23EMD which has more prominent S-duct and a DSI inlet
Something is built later doesn't automatically mean it is better on all front, X-32 was built 10 years later than YF-22 and YF-23 and it is slower, carry less missile , with smaller radar, less agile .... so on. The point is: they have different requirements.
No one ever said Boeing engineers are stupid, no need to repeat that, it is a strawman argument. S-duct and turbine blocker has their own advantages and disadvantages. Blocker has advantage in lighter weight and smaller volume while S-duct has advantage in signature. You can have two design satisfied the same requirement and yet they can be different. For example: let say your requirement is making a fighter that can fly faster than Mach 1=> F-35 and F-16 can satisfy that but they aren't equally fast.

Diffracted is absent when using a composite blocker.
The whole point of the blocker is to stop radar wave from reaching the turbine blades, if you make them transparent to radar wave then what the point of having them in the first place?
 

Bhurki

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AGS-1787

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Don't underestimate the Russians, I have seen a guy on youtube build two houses and a sailboat; the sailboat was enormous and when he finished it looked like he bought it from a factory, incredible stuff. It is like they just get on doing things instead of overthinking things too much.
 

tanino_it

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I believe there will be more videos and photos from the production facility. An action in the public domain to combat the reputation of lower quality than the competition. Well done.

Next comes time to review the overall RCS level of the Su-57. Which I imagine is better.
 

FighterJock

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Su-57 assembly line
Are the darker gray parts titanium? I'm surprised how little spars are on the nose section next to the round sensor, I imagine the skin and internal components give it rigidity.

I thought that the dark grey parts were carbon composites? All the YouTube videos that I have watched on the PAK-FA/ Su-57 have stated that the PAK-FA/Su-57 have made great use of carbon composites over the previous generation such as the MiG-29/Su-27. :confused:
 

AGS-1787

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I thought the light grey on the skin was carbon composite, yellow aluminium, and dark titanium, for example where the exhaust goes next to the tail stinger. Is that coorect? Inside the engine, compartments look like dark grey.
 

Trident

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I thought the light grey on the skin was carbon composite, yellow aluminium, and dark titanium, for example where the exhaust goes next to the tail stinger. Is that coorect? Inside the engine, compartments look like dark grey.

That sounds about right. Many of the light grey panels have been displayed separately as composite parts, so we know what they're made of.
 

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