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PAK FA stealth features patent published

Kurama

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PAK_stealth_-_main.jpg

This profile view of the PAK FA illustrates the extensive shaping that has been done in an effort to reduce the usual radar-returning traps around the air intakes. Source: Sukhoi

Details of the Sukhoi Design Bureau's work on the stealthy aspects of the T-50 PAK FA fighter aircraft emerged in late December 2013, when the company's patents were published.

According to the patent paperwork, taken together, all of the stealthy measures offer significant improvements over legacy fighter designs. The papers claim that the radar cross-section (RCS) of an Su-27 was in the order of 10-15 m 2 , with the intention being to reduce the size of the RCS in the T-50 to an "average figure of 0.1-1 m 2 ".

In common with other low observable aircraft designs, this reduction is achieved throught the use of radar-absorbing and radar-shielding materials and coatings, panel shaping (especially around the air intakes) and in the design of the junctions between moving elements, such as flaps and hatches.

In particular, the patent spells out the benefits of internal weapons carriage, s-shaped engine air ducts, (which were considered but are actually not implemented in the production PAK FA), and the use of radar blockers. It adds that the inlet guide vanes of the engines' compressors generate "a significant portion [up to 60%] of the radar cross-section of the airframe-powerplant system in the forward hemisphere" and that this is reduced by using radar-blocking devices and radar-absorbing coatings in the walls of the air ducts.

The shape of the airframe reduces the number of directions that radar signals are reflected in with the angles of sweep of the wings and the tail plane's leading and trailing edges, the edges of the air intakes and hatch covers being reduced and deflected from the aircraft's axis. Viewing the aircraft from the flank, the fuselage sides, lateral edges of the air intakes and vertical empennage are all deflected at the same angle.

Some openings and slots on the airframe's surface - such as the boundary-layer bleeds on the sides of the air intakes and the openings on the upper fuselage immediately aft of the cockpit - are covered with a thick grid, featuring a mesh of less than one quarter of the wavelength of a search radar, which reduces the reflections from these uneven surfaces. Gaps between the airframe elements are filled with conducting sealants, while the glazing of the cockpit canopy is metallised.

The surfaces of the PAK FA's own five radar arrays are also angled off from the vertical plane, helping to 'deflect' enemy radar signals. The covers of the radar arrays are selective, letting through their own signals, but blocking other frequencies. Additionally, the array compartments are edged with radar-absorbing 'curtains' to reduce possible leaks of these amplified signals.

Antennas are recessed from the surface of the skin to reduce protuberances (the vertical empennage serves as a communications antenna), while the turret of the aircraft's nose-mounted infrared search-and-track (IRST) sight is rotated backwards into a cruise position, exposing its rear hemisphere, which is covered with a radar-absorbing coating.

The release of this list of patents follows the July 2013 release of documentation covering the configuration of the fighter's integrated avionics suite.

There are currently five T-50 prototypes - the latest, T-50-5, first flew on 27 October 2013 - supporting the development programme and they are believed to have undertaken over 300 sorties to date.

In the 'Schedule of Activity for the Russian Ministry of Defence for 2013 to 2020' published in mid-2013, the PAK FA's Initial Operational Capability and the launch of full-scale series production is scheduled for 31 December 2016. The Russian National Armament Programme stipulates that 60 production PAK FA fighters will be delivered between 2016 and 2020.

The assembly of aircraft T-50-6-1 is nearing completion and three further aircraft (T-50-6-2, T-50-7 and T-50-8) are in build. One of the T-50-6 aircraft is intended for static trials and the other one is intended for flight testing.



p1481151.jpg

The PAK FA's designers have paid close attention to stealthy features, which include the use of radar-absorbent coatings on the reverse of the nose-mounted IRST, the widespread use of baffles and the use of absorbent coatings in the air intakes and at the junctions between moving surfaces. (Sukhoi)

PAK FA stealth features patent published - IHS Jane's 360
 
The papers claim that the radar cross-section (RCS) of an Su-27 was in the order of 10-15 m 2 , with the intention being to reduce the size of the RCS in the T-50 to an "average figure of 0.1-1 m 2

Thats bullshit..!!
RCS of a clean Rafale is 0.3m2.
RCS of F-22 :: 0.00004 m2 (On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm..!! And i dont know why..?!)
RCS of F-35 :: 0.0001 m2
RCS of PAK-FA :: 0.001 m2

(Those are all in the Frontal Section with X-band radars.)
Perhaps the 0.1sqm for the PAK FA is with external weapons?
 
.
RCS of F-22 :: 0.00004 m2 (On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm..!! And i dont know why..?!)
RCS of F-35 :: 0.0001 m2
RCS of PAK-FA :: 0.001 m2

This means RCS of PAKFA is even more than F-35? Not very good then !!
 
This means RCS of PAKFA is even more than F-35? Not very good then !!
The design philosophy of the PAK-FA/T-50 is not to be the stealthiest plane in the sky, but rather just stealth enough to get close where it'll win almost all the time v.s. the F-35 and have a chance v.s. the F-22.
 
F-35 is half the size of PAK-FA. More over PAK-FA is a twin engine jet unlike F-35 a single engine jet. PAK-FA is made to be semi-stealth. Thus no comparison.
 
F-35 is half the size of PAK-FA. More over PAK-FA is a twin engine jet unlike F-35 a single engine jet. PAK-FA is made to be semi-stealth. Thus no comparison.
Its not about size...its all about not getting caught and bypassing radar networks.
 
Thats bullshit..!!
RCS of a clean Rafale is 0.3m2.
RCS of F-22 :: 0.00004 m2 (On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm..!! And i dont know why..?!)
RCS of F-35 :: 0.0001 m2
RCS of PAK-FA :: 0.001 m2
(Those are all in the Frontal Section with X-band radars.)
Perhaps the 0.1sqm for the PAK FA is with external weapons?
Buddy, it's the patent paper which published the Pak-fa RCS, know body knows the true RCS among us for any plane.. :tup:
 
Its not about size...its all about not getting caught and bypassing radar networks.

OR

Being able to carry more missiles,more range,more gadgets. Its about completing the mission, its about survivability. Sooner or later someone WILL come up with a way to track stealthy jets.
 
As far as I remember the F22 rcs mentioned (0.3 ) is untreated/coated/ without smart skin. So I believe this is the first step of achieving the lower RCS ( Shape) second step would be some localized modifications/treatments (like edges etc), radar blockers and finally nano paint for radar waves absorption.
The RCS currently mentioned may the initial one (step 1), with 2 more rounds of refinements needed/pending. Pl correct me if wrong.
 
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Thats bullshit..!!
RCS of a clean Rafale is 0.3m2.
RCS of F-22 :: 0.00004 m2 (On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm..!! And i dont know why..?!)
RCS of F-35 :: 0.0001 m2
RCS of PAK-FA :: 0.001 m2

(Those are all in the Frontal Section with X-band radars.)
Perhaps the 0.1sqm for the PAK FA is with external weapons?

Its not RCS of Rafale. Its RCS of some frontal magic angle of Rafale. The same applies to any other plane.
You are comparing minimal RCS with average RCS.
 
in short tell me will it be more stealthier than f22,f35 or not?
if it will be than it is usefull
else a paper plane after being inducted 1-2 decades later than f22
 
Thats bullshit..!!
RCS of a clean Rafale is 0.3m2.
RCS of F-22 :: 0.00004 m2 (On the Sukhoi website, they state that the RCS of the F-22 is 0.3sqm..!! And i dont know why..?!)
RCS of F-35 :: 0.0001 m2
RCS of PAK-FA :: 0.001 m2

(Those are all in the Frontal Section with X-band radars.)
Perhaps the 0.1sqm for the PAK FA is with external weapons?

The 0.1 m2 figure is the "average RCS" which is determined by analyzing the front, rear, sides, top
& bottom angles and finally arriving at an overall average figure.

In the case of F-22's 0.0001 m2 or F-35's 0.001 m2, that's the frontal sector RCS only. If you
consider all-aspect average RCS of those aircraft, it'll be a lot bigger again.
 

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