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Sukhoi Su-57 / PAK FA 5th Generation Aircraft

Discussion in 'Indian Air Force' started by tariqkhan18, Jun 30, 2010.

  1. gambit

    gambit FULL MEMBER

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    You do not know what you are talking about. Shaping is the primary mode/method of RCS control for the current US 'stealth' designs.
     
  2. grond

    grond Captain SENIOR MEMBER

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    Thanks in more ways than one . I was trying to pitch a simulation of a flying wing to my friends that turns on active aeroelastic wings ... But yeah now I know that the pitch can't be successful as such a system would greatly compromise the rcs when turning... So I have to select the original design .... And yes for the tail section as well....
     
  3. G777

    G777 Lt. Colonel ELITE MEMBER

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    Oops, sorry I was not specific, the Pak Fa was designed for very low frontal RCS with its fuselage (or body shape) radar shaping however when you look at the B2 head on which has too many rounded areas and curves.

    [​IMG]

    [​IMG]

    They say the F35 has RCS hotspots due to its rounded areas, flat areas have better effect on RCS as you will already know.

    [​IMG]

    [​IMG]

    I think the US could have given the B2 more of a diamond shape however that would compromise the aerodynamic lift from being a wing.
     
    Last edited: Sep 15, 2012
  4. Picard

    Picard Lt. Colonel RESEARCHER

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    It doesn't matter wether it's curve or a flat surface as long as it does not reflect waves back to the receiver. B-2 is designed to reduce return towards receiver of monostatic ground-based radar, thus frontal, side and back RCS was reduced as much as possible, whereas fighters would have easier time picking it up from some angles (granted, whenever you reduce RCS from one angle, you increase it from other angles; but B-2, having many curved surfaces, presents larger angles of increased return than, say, F-117. However, that does not matter much against ground-based radars).

    B-2 is not expected to maneuver lot, even when turning to left/right it remains level, thus flying wing shape was acceptable.
     
  5. trendmaker1

    trendmaker1 REGISTERED

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    I think RCS of B 2 will be greater than pak fa due to its large size but the gap will be less due to b 2's superior design..:azn::evilgrin:
     
  6. gambit

    gambit FULL MEMBER

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    Actually, curvatures are more effective than angular faceting method in two important areas: Aerodynamics and RCS control.

    There is a misconception based upon inadequate publicly available knowledge that a curvature is detrimental for RCS control. Nothing could be further from the truth, as the cliche saying goes.

    [​IMG]

    Upon a curvature from a sphere, a spheroid, or cylinder, a curvature induces surface traveling waves. There is that tiny amount of specular reflection because there is always a tiny amount of surface area that is sufficiently flat to reflect directly back to incidence direction. The rest of the signal's energy -- most of it -- is turned into surface wave behavior. The physical surface is called the 'electrical path' and the longer this path, the greater the energy loss through 'leaky waves' that does not return to incidence direction. This is what we want. If the diameter is greater than ten wavelengths (lambda), then the 'creeping wave' behavior will not exist. This somewhat esoteric rule is appropriately called the 'ten lambda rule'.

    And if anyone thinks I make this stuff up...

    [​IMG]
    Notice the names of the authors. Certainly not American.

    If diameter is greater than ten wavelengths -- any wavelength/frequency -- then the creeping wave behavior will not exist and contribute to RCS. If diameter is less than ten-lambda, the creeping wave behavior will exist and contribute to RCS. That is the 'ten lambda rule'.

    Now, if we take a plate...

    [​IMG]

    ...We will have a time when the plate present the seeking radar with nearly the full strength reflection -- perpendicular. Other than completely perpendicular, the approach/incidence angle is called the 'grazing angle'.

    If the plate is completely horizontal the incidence angle, we have a tiny amount of specular reflection plus edge diffraction...

    [​IMG]

    If we rotate the plate, we will have a cyclical or rhythmic rise/fall of RCS. Highest when the plate is perpendicular. Lowest when the plate is horizontal. In other words -- a strobe.

    In radar detection, nothing is more beneficial to the seeking radar than something predictable -- like a strobe. Whereas, if we rotate the sphere or the diameter of the cylinder, both will produce one consistency -- specular.

    That is why we did away with the angled faceting technique of the F-117. Too many plates. That is not to say the method is not helpful in controlling RCS. It does. But when use judiciously, both the curve and the plate have their advantages and disadvantages. For now, the curve is the dominant surface shape in RCS control.

    Finally, we want a convex curvature...

    [​IMG]

    ...Not a concave version, which is actually an amplifier and is used in radar enhancing devices.
     
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  7. Averageamerican

    Averageamerican Colonel ELITE MEMBER

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    Are you all hearing any rumors the Russian Indian PAKFA deal might be in trouble? That India might be have second thoughts.....
     
  8. trendmaker1

    trendmaker1 REGISTERED

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    india doesn't have any other options..!!:pop:

    INDIAN FGFA WILL ROLL OUT IN 2014


    By: DAVE MAJUMDAR WASHINGTON DC 07:37 22 Aug 2012 Source:

    India's fifth-generation fighter aircraft (FGFA), which the country is co-developing with Russia, is set to be rolled-out in 2014, the Indian air force's (IAF) top uniformed officer says.

    "The first prototype of the FGFA is scheduled to arrive in India by 2014 after which it will undergo extensive trials at the Ojhar air base," Air Chief Marshal NAK Browne says. "We are hopeful that the aircraft would be ready for induction by 2022."

    A second prototype is expected to arrive in India in 2017 while a third should arrive in 2019.


    ©Sukhoi

    India expects to sign an $11 billion development contract for the aircraft with Russia soon according to press reports in that country.

    India hopes to eventually purchase some 214 of the stealthy fifth-generation fighter by 2030. The total cost of the programme is expected to cost the Indian government over $30 billion. The Indian FGFA is based on the Russian Sukhoi T-50 PAK-FA but has added features which are required by the IAF.

    There are currently three PAK-FA prototypes flying in Russia. A fourth aircraft is expected to join the fleet soon.
     
  9. Gessler

    Gessler BANNED BANNED

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    What is the typical wavelength of an S-band Active Phased Array/AESA?

    I have known two types of radar enclosures aboard stealth-optimised warships, I'm taking into notice
    the Type-45 Daring and the P-15A Kolkata DDG (under construction),,,is it possible that a spherical
    enclosure like the radome of the T45D is a proefficient RCS-contributor than compared to the
    P-15A's radome that is an angled-surface casing?

    Daring's SAMPSON radome -
    [​IMG]

    Kolkata's EL/M-2248 MF-STAR radome -
    [​IMG]

    ^^ Regretting it the MF-STAR's casing is a mock-up and the real radar on the P15A DDG is not available
    on the net as the ship will be commissioned only in March 2013:sad: But I believe you can estimate the
    actual aspect & response of probing radar waves on these two types of surfaces and can you tell me
    which enclosure envisages lesser radar return ??
     
    Last edited: Sep 16, 2012
  10. Averageamerican

    Averageamerican Colonel ELITE MEMBER

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    Figure your right its like the tejas fighter, too many polticans and military careers on the line to pull out now....well, good luck I have a feeling you are going to need it.
     
  11. gambit

    gambit FULL MEMBER

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    You can find that here => Radar Bands and Wavelengths

    But this is to give you approximations of physical lengths to each other...

    [​IMG]

    The illustration is not to physical true wavelengths but to show comparative lengths to freqs.

    It is...But that is not the real reason why a spherical radome is used.

    SAMPSON - Wikipedia, the free encyclopedia
    Note -- An antenna is not the same as an array. An antenna is technically an 'assembly' and usually CONTAINS the array. So if you have a structure that holds two ES-arrays, that structure is technically the 'antenna'. But even engineers casually uses the two words interchangeably.

    Anyway -- An ESA or planar antenna is no different than that of the classical concave dish in that they are all directional, meaning they do not radiate behind them. Their reception is also directional, meaning only to wherever they are pointing at. So if the goal is to provide all-around coverage in both transmission and reception, either we install four arrays or rotate one. Only the straight up rod antenna is omnidirectional and that is still in use today in some applications.

    The SAMPSON's spherical radome is more for environmental protection rather than for low observability, even though that is a side benefit. You can find plenty examples of spherical radomes here => Radome - Wikipedia, the free encyclopedia

    You can calculate that detection distance here => Horizon calculator - radar and visual
     
    Last edited: Sep 17, 2012
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  12. Teja

    Teja REGISTERED

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    Same for ur F35 guys ...
    You will also be eeding lots of luck for ur F35
    Hope it gets operational within the next 5 -10 years...
     
  13. halloweene

    halloweene Major MILITARY STRATEGIST

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    Thx for debunking misconceptions about faceted vs curvatures shapes Gambit :yes4:
     
  14. Gessler

    Gessler BANNED BANNED

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    Sukhoi T-50 caught vectoring it's nozzles

    [​IMG]
     
    2 people like this.
  15. Averageamerican

    Averageamerican Colonel ELITE MEMBER

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    Thanks, think we are OK










    Air Force to start operational testing of F-35




    By Dave Majumdar - Staff writer
    Posted : Friday Jul 15, 2011 17:51:16 EDT



    Even as the first F-35 Lightning IIs arrive at the training unit at Eglin Air Force Base, Fla., the Air Force is preparing for operational testing of the aircraft, said the service’s deputy chief of staff for operations, plans and requirements.

    “There are going to be 422[nd Test and Evaluation Squadron] guys flying the F-35 at Edwards [AFB, Calif.,] right away,” Lt. Gen. Herbert “Hawk” Carlisle said. “As the F-35s are going to Eglin, there’s F-35 [operational test pilots]… that are going to Edwards and do Operational Test and Evaluation.”

    The soon-to-be-activated Edwards detachment will do its initial operational evaluations at the California base, but the remainder of the evaluation will be done by the main body of the 422nd TES at Nellis Air Force Base, Nev. One series of tests is planned for the Block 3C software needed for initial operational capability, as well as the preceding software blocks, Carlisle said.

    The service, along with the F-35 Joint Program Office, is still working on a Test and Evaluation Master Plan, slated for release in November.

    “The JPO is currently estimating Ops Test of Block 2B to commence in early 2015 and complete in early 2016, and the [Operational Test] for Block 3C IOC capabilities to commence in mid-2016 and to end in early 2018,” said Air Force spokesman Maj. Chad Steffey.

    The service’s Air Combat Command has not set a new IOC date for the F-35.

    Carlisle said that the F-35 could be a valuable combat asset even with the earlier Block 2B software.

    “Block 2B has capability that if the combatant commander needed it, we would deploy it. Would it be IOC? No,” he said.

    “We in the Air Force designated a set of capabilities to include [Suppression of Enemy Air Defenses], [Destruction of Enemy Air Defenses], air-to-ground and some air-to-air capability that we consider the minimum required for initially operational capable,” he said.

    He noted that the Air Force has deployed many aircraft that had not yet formally entered service, including the F-15E Strike Eagle, MQ-9 Reaper UAV and the E-8 Joint Surveillance and Target Attack Radar System surveillance plane.

    The F-35 even outpaces its larger twin-engine cousin, the F-22 Raptor, in certain areas, including electronic countermeasures and electronic counter-counter measures. Carlisle also praised the jet’s infrared sensors and air-to-ground radar as “phenomenal.”

    Carlisle said the Raptor retains a huge kinematic advantage — “at 51,000 feet and [Mach] 1.7, it’s a pretty hard target to hit” — but said the F-35 can “take out those [integrated air defense] systems and to penetrate using all of its attributes to the point that it can do incredible damage.”

    Carlisle said the operating cost of the both the F-22 and F-35 are a major concern. But he said that F-22 operating costs would likely decrease over time. The service is learning how to better maintain the jet’s stealth coating, and many lessons have been learned that will carry over to the F-35. Further, he said, while the operating costs estimates for the F-35 are high, they are speculative at this point because there is very little real world data to backup those estimates.

    In the meantime, the Air Force has started to seriously look at the capabilities it will need in the jet that replaces the F-22 and F-35.

    “We’re definitely thinking about a sixth-generation fighter,” he said. “But it’s 2030-plus.”

    He said that the U.S. must continue to invest in new technologies.

    He said the Chinese and Russians are making slow progress in stealth, a tough technology to master. Neither has yet developed a good pilot vehicle interface, which is an important aspect of building fighters, but is particularly important for stealth aircraft because of the need to manage radar signatures in-flight, Carlisle said.

    “They’re getting better than they used to be, but they’re still a long ways behind us in pilot vehicle interfaces,” he said.

    Carlisle is a veteran fighter pilot who in his earlier years was part of an elite group of Air Force aggressor pilots selected to fly Russian and Chinese aircraft acquired via various means.

    The problem for the United States will be that though the country will continue to lead the world in military technology, other nations will able to match those capabilities far more quickly than in years past due to cyber threats and globalization. Instead of decades at a time, the U.S. edge will last for years at a time — but he reiterated that that does not mean the U.S. is falling behind.

    “Given the world we live in today,” Carlisle said, “My belief is that we’ll continue to continually push the technological envelope… I just think that our ability to have that technological advantage will be for a shorter period of time.”
     

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