Шумности
Известный американский исследователь подводного флота и продолжатель идей Н. Полмара Вепрь157 так прокомментировал фото ниже и замечания пользователей к ней на rddt
667БДР
- There's a little (apparently) adjustable control surface behind and a little above the reactor coolant intakes, I wonder what purpose that serves?
- It's probably not adjustable. It's a vortex generator, which cancels out an undesirable vortex that causes noise, drag, and adds to the non-acoustic signature. There's another one above the one you mentioned. Another example of such a device is the plate at the base of the sail of some of the Charlie SSGNs.
This destroyed a ring vortex that was interfering with the sonar in the sail.
The screws themselves are probably 1990s or early 2000s vintage, so a little younger.
Вепрь обновил сравнительные данные по шумностям ПЛА. В цеелом весьма логично и отражает западный дискурс. Есть, конечно взаимоисключающие неточности.
I think the Ohio SSBNs and the Narwhal may have been quieter than Soviet submarines, but the SSNs (Sierra, Akula, Victor III) were at a similar level to the Los Angeles class SSNs being built at the time. In 1995, the Russians surpassed the quieting of the contemporary US SSN and we've been on pretty much equal footing ever since.
The effectiveness of passive sonar is effectively a multiplier to quieting, so even if the Soviet and US/British submarine had the same acoustic quieting, the Soviet submarine could be much more easily tracked.
The Sierra I (and probably II) was probably pretty loud for its generation because the displacement was constrained by the size of the yard at Gor'kiy, and thus could not be equipped with the extensive rafting that made its way onto the Akula class. I'm guessing that part of the reason why the Akula and US Seawolf classes were so quiet for their time were their wide beams, which allowed for easier noise isolation.
Also, Soviet submarines in the 80s had an advantage over the Los Angeles class in that their reactors had natural circulation and did not need to use coolant pumps at low speed (unlike the surface ship derived S6G on the Los Angeles class). This technology was only implimented on the Ohio SSBNs and the Narwhal at the time.
As to why the Akula II (K-157 Vepr') was quieter than a 688I: it must have been persistent improvement in quality control. Although the Vepr' was 3 meters longer in the propulsion spaces than a standard Akula, which was for extra quieting, quality control is the biggest factor in modern submarine stealth. This was proven when one of the US Sturgeon class turned out be very loud due to many minor defects in machinery and noise isolation parts. The Soviets/Russians had refined their reduction gear machining by this point, so I can only assume that the rest of the submarine followed. The Soviet industrial complex still had a huge amount of momentum through the mid-90s and it was only with new construction boats did it start to crumble. Now the Severodvinsk is (allegedly) louder than expected, so they may have to go through the arduous journey of slow quality control improvement again.
Внешне сигара как сигара, а на самом деле очень сложно устроенный космический корабль.
667БДР
- There's a little (apparently) adjustable control surface behind and a little above the reactor coolant intakes, I wonder what purpose that serves?
- It's probably not adjustable. It's a vortex generator, which cancels out an undesirable vortex that causes noise, drag, and adds to the non-acoustic signature. There's another one above the one you mentioned. Another example of such a device is the plate at the base of the sail of some of the Charlie SSGNs.
This destroyed a ring vortex that was interfering with the sonar in the sail.
The screws themselves are probably 1990s or early 2000s vintage, so a little younger.
Вепрь обновил сравнительные данные по шумностям ПЛА. В цеелом весьма логично и отражает западный дискурс. Есть, конечно взаимоисключающие неточности.
I think the Ohio SSBNs and the Narwhal may have been quieter than Soviet submarines, but the SSNs (Sierra, Akula, Victor III) were at a similar level to the Los Angeles class SSNs being built at the time. In 1995, the Russians surpassed the quieting of the contemporary US SSN and we've been on pretty much equal footing ever since.
The effectiveness of passive sonar is effectively a multiplier to quieting, so even if the Soviet and US/British submarine had the same acoustic quieting, the Soviet submarine could be much more easily tracked.
The Sierra I (and probably II) was probably pretty loud for its generation because the displacement was constrained by the size of the yard at Gor'kiy, and thus could not be equipped with the extensive rafting that made its way onto the Akula class. I'm guessing that part of the reason why the Akula and US Seawolf classes were so quiet for their time were their wide beams, which allowed for easier noise isolation.
Also, Soviet submarines in the 80s had an advantage over the Los Angeles class in that their reactors had natural circulation and did not need to use coolant pumps at low speed (unlike the surface ship derived S6G on the Los Angeles class). This technology was only implimented on the Ohio SSBNs and the Narwhal at the time.
As to why the Akula II (K-157 Vepr') was quieter than a 688I: it must have been persistent improvement in quality control. Although the Vepr' was 3 meters longer in the propulsion spaces than a standard Akula, which was for extra quieting, quality control is the biggest factor in modern submarine stealth. This was proven when one of the US Sturgeon class turned out be very loud due to many minor defects in machinery and noise isolation parts. The Soviets/Russians had refined their reduction gear machining by this point, so I can only assume that the rest of the submarine followed. The Soviet industrial complex still had a huge amount of momentum through the mid-90s and it was only with new construction boats did it start to crumble. Now the Severodvinsk is (allegedly) louder than expected, so they may have to go through the arduous journey of slow quality control improvement again.
Внешне сигара как сигара, а на самом деле очень сложно устроенный космический корабль.