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95 posters

    Project 885: Yasen class

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    limb

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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  limb Thu Dec 24, 2020 5:13 am

    kvs wrote:Nobody designs properly hydrodynamic shaped submarines like Russia.  

    Project 885: Yasen class - Page 40 1920px-SSN774.svg

    Project 885: Yasen class - Page 40 1920px-Graney_class_SSN.svg

    Does hydrodynamic shaping allow reduced cavitation at higher speeds and thus less noise?

    It seems like westerners say only the pumpjet works for reducing high speed noise, which is wierd.
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    walle83

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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  walle83 Sat Jan 16, 2021 9:36 pm

    kvs wrote:Nobody designs properly hydrodynamic shaped submarines like Russia.  

    Project 885: Yasen class - Page 40 1920px-SSN774.svg

    Project 885: Yasen class - Page 40 1920px-Graney_class_SSN.svg


    Altough the sail on the Yasen look alot bulkier then on the old Alfa class. Or the Akula for that matter.

    Project 885: Yasen class - Page 40 Yasen10
    Project 885: Yasen class - Page 40 Alfa10
    Project 885: Yasen class - Page 40 Akula10
    kvs
    kvs

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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  kvs Sat Jan 16, 2021 10:40 pm

    The cavitation noise from the propeller (only under full load) is not the only source of noise. The hull pushing through the water
    is another source of longer wavelength noise. This includes turbulence and the deformation (vibration) of the hull. Nothing
    the size of a submarine is a perfectly stiff object. It deforms in all sorts of ways. Long wavelength acoustic detection is
    a real thing in naval warfare.

    So conforming to hydrodynamic "aesthetics" is not superfluous but rather necessary. The US submarine tower is not only ugly,
    it is noisy even if it is shaped like a fin in horizontal section. The sloping contour on the tower of the Russian submarine is not
    a decoration. Also, pushing through water requires a shape that is not like a conic wedge with a taper to a leading point, but the
    reverse with a nearly spherical frontal contact with a trailing shape like a tear drop. The US submarine in the graphic was
    designed by someone barely aware of this detail and they were clearly going for a bullet penetrator shape, which is simply
    the wrong approach. It may not look like much of a difference, but the Devil is in the details. The goal is to reduce the
    disturbance of the flow contours and any transitions generate transients.

    Pump jets are something every fanboi trots out a proof of their vicarious achievement credentials. Pump jets reduce
    the propulsion efficiency and cavitation is only an issue at the limit of propeller rotational speed. Lots of effort is expended
    designing propellers that push the cavitation regime to the high rotation limit. The decision to use a shroud only for the
    missile carrier submarines makes perfect sense. Not hobbling the attack submarines with this feature is the right choice.
    There is a trade off between speed under water and noise reduction. The Borei class has a pump jet and a tower that
    is not shaped with the sort of streamlining as the Yasen class because it mostly crawls around under water and is not
    intended for rapid maneuvers.

    The Yasen-II pump jet is a whole new design that is supposed accommodate a much larger diameter propeller with a shorter
    shroud length. That makes perfect sense to me. The propulsion efficiency goes up with such modifications since shroud
    drag is reduced.

    https://www.popularmechanics.com/military/navy-ships/a13990706/russias-new-missile-submarine-sure-looks-familiar/

    An example of the masturbation common in western coverage of Russia. Clowns teaching Russians about hydrodynamics.
    Recall that Kolmogorov was from Russia and not the USA. To this day nobody has come up with any improvement on
    his unstratified turbulent boundary layer theory. And the people working on coming up with an extension to stratified
    boundary layers for geophysical applications are from Russia as well.


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    Isos
    Isos

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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  Isos Sat Jan 16, 2021 10:48 pm

    I've seen somewhere the best design in terms of noise reduction is the water drop.

    Kilo class is similar to it and thus has the best noise reduction design.

    For the sail it's better not to have it. They can design periscops that raise without the need to put a sail.

    That's the future of SSK IMO.
    Big_Gazza
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    Post  Big_Gazza Sun Jan 17, 2021 12:37 am

    limb wrote:Does hydrodynamic shaping allow reduced cavitation at higher speeds and thus less noise?

    Cavitation doesn't occur at all if you operate at a sufficient depth as water pressure is high enough to ensure that screw rotations doesn't result in regions having an absolute lower than water vapour pressure at the prevailing temperature.  Cavitation is also less of a factor in cold water as the vapour pressure is proportional to water temperature - Russian boats running deep in polar seas are much less affected than USN boats (or Chinese) running in shallow depths in warmer pacific waters.

    Don't expect the budweiser-swilling NASCAR-watching NRA members over at The Drivel to understand any of this however.  They just want to read yee-haa inducing feel-good nonsense while they wave their flags and stroke their inadequate weiners.. Twisted Evil

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    George1
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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  George1 Fri Feb 05, 2021 5:36 pm

    The lead multipurpose nuclear submarine "Kazan" of project 885M (Yasen-M) will be handed over to the customer at the end of February.

    https://en.topwar.ru/179709-nazvany-sroki-peredachi-flotu-apl-kazan-proekta-885m-jasen-m.html

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    Singular_Transform
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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  Singular_Transform Fri Feb 05, 2021 10:22 pm

    kvs wrote:Nobody designs properly hydrodynamic shaped submarines like Russia.  

    Project 885: Yasen class - Page 40 1920px-SSN774.svg

    Project 885: Yasen class - Page 40 1920px-Graney_class_SSN.svg


    This picture not scaled, the Virignia smaller than the Yassen, but all pcitures comparig them showing both in the same size category.


    In reality they are like a frigatte vs. destroyer.

    Project 885: Yasen class - Page 40 Dvzos9e3dcp01

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    Singular_Transform
    Singular_Transform

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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  Singular_Transform Fri Feb 05, 2021 10:27 pm

    Project 885: Yasen class - Page 40 Virgin10

    Scaled version of the above picture.

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    Big_Gazza
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    Post  Big_Gazza Fri Feb 05, 2021 11:52 pm

    The Vanguard class are SSBNs. Not a useful comparison.

    Interesting how the old CW-era propaganda was that Soviet boats were cramped with little attention to crew comfort (cuz the dastardly commies hate people and are evil...) yet the Yasen turns this paradigm on its head.  Its automation levels are an order of magnitude ahead of what the Virigina has, and its crew is only 64 vs the Virginias 135 (less than half) even though the Yasens submerged displacement is nearly 75% greater. Modern Russian boats have generous accomodations while Murican boats are cramped and spartan (and IIRC they use 'hot-racking" where the number of beds is less than the number of crewmen). How 3rd-world of them Laughing Laughing Laughing

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    Isos
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    Post  Isos Sat Feb 06, 2021 12:07 am

    Yasen is the best sub ever created. It is just perfect in terms of size, design, weapon load and crew number.

    It will be hard to make better. I guess the only way to make it better is to create some sort of build-in propulsion to reduce the noise of the propellers.
    PapaDragon
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    Post  PapaDragon Sat Feb 06, 2021 1:01 am

    George1 wrote:The lead multipurpose nuclear submarine "Kazan" of project 885M (Yasen-M) will be handed over to the customer at the end of February.

    https://en.topwar.ru/179709-nazvany-sroki-peredachi-flotu-apl-kazan-proekta-885m-jasen-m.html

    Good

    Now order more

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    Singular_Transform
    Singular_Transform

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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  Singular_Transform Sat Feb 06, 2021 12:00 pm

    PapaDragon wrote:
    George1 wrote:The lead multipurpose nuclear submarine "Kazan" of project 885M (Yasen-M) will be handed over to the customer at the end of February.
    https://en.topwar.ru/179709-nazvany-sroki-peredachi-flotu-apl-kazan-proekta-885m-jasen-m.html
    Good
    Now order more

    It is a milestone for the Russian military indsutry.

    All other highly sophisticated (non ballistic) submairne up to Kazan was manufactured from leftower Soviet parts.

    The Kazan is the first whole Russian made nuclear attack submarine.

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    Singular_Transform
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    Post  Singular_Transform Sat Feb 06, 2021 12:09 pm

    walle83 wrote:

    Altough the sail on the Yasen look alot bulkier then on the old Alfa class. Or the Akula for that matter.


    Most likelly they needed the extra height for the mast system, for missile launch.

    Oscar sail looks similar, and that had to peek out from water before missile launch.

    Akula/alfa supposed to stay deep in the water, and hunt submarines with sonars/sensors.
    George1
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    Post  George1 Sat Feb 06, 2021 3:14 pm

    Severodvinsk", in accordance with the combat training plan, hit a coastal target at a training ground in the Arkhangelsk region with a cruise missile "Caliber". This was reported on Friday by the press service of the fleet.

    https://tass.ru/armiya-i-opk/10635379

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    owais.usmani

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    Post  owais.usmani Thu Feb 11, 2021 1:19 pm

    https://iz.ru/1123010/2021-02-10/atomnuiu-submarinu-kazan-smogut-peredat-vmf-v-kontce-fevralia

    The lead nuclear submarine "Kazan" can be handed over to the Russian Navy on 26 February. This was announced on Wednesday, February 10, by the head of the United Shipbuilding Corporation (USC) Alexei Rakhmanov.

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    mnztr

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    Project 885: Yasen class - Page 40 Empty Re: Project 885: Yasen class

    Post  mnztr Fri Feb 12, 2021 11:20 pm

    Singular_Transform wrote:
    kvs wrote:Nobody designs properly hydrodynamic shaped submarines like Russia.  

    Project 885: Yasen class - Page 40 1920px-SSN774.svg

    Project 885: Yasen class - Page 40 1920px-Graney_class_SSN.svg


    This picture not scaled, the Virignia smaller than the Yassen, but all pcitures comparig them showing both in the same size category.


    In reality they are like a frigatte vs. destroyer.

    Project 885: Yasen class - Page 40 Dvzos9e3dcp01

    I would consider Yassen class to be a nuclear cruiser or destroyer class.

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