In this article we are going to deal with various design aspects of Akula class SSN using pictures. This article, like its preceding article on Typhoon has some very rare pictures of Akulas under construction, trials, refit and pics of her sensors.
This is K-284, ie the lead boat of the Akula class under construction. She was named as Akula and thus NATO used it as the official reporting name for the entire class.
In this pic we can see that the rudder and stern planes have small sections which arent connected with the main controlled surface. These smaller surfaces were exclusively used for making small direction changes at high speeds.
Here we can see K-154’s cylindrical array on the bow as its covering was damaged due to some reason. This array along with several small ones on the sail, wide aperture arrays and the towed array made the Akulas a potent sonar platform and this became a major factor in its supremacy over the LA. The Russians stuck to cylindrical arrays even though Americans had spherical arrays as they wanted to stick with tubes mounted on the bow instead of amidships like the American subs. Tubes which deployed torpedoes from amidships couldnt be used at higher speeds but bow mounted ones could be used at comparatively higher speeds. Thus a smaller spherical array was sought after, but over head tubes meant it was only a minor increase in capability yet caused lots of problems.
Originally the west thought that the bulb on the rudder was a new propulsion system or a new counter measure/weapon which could be deployed rearwards. It turned out to be a towed sonar array housing which was first seen on Victors after which they were fitted onto Akulas and Sierras. These subs needed the pod as they didnt have enough space between their inner and outer hulls to house the array there. The bulbs on Akulas were larger than others and were almost as big as a minibus.
Towed array cable being fed into the bulb by the reel.
On the other hand K-335 features a tube towed array dispenser as seen on Yankees, Oscars, Yasens, Typhoons and Deltas. She stores the cable in her sail, which is larger and taller compared to other Akulas. It is also said that the bulb and sail cancel each other’s wakes and in K-335 as the bulb was removed thus the design of the sail was changed to achieve the same performance.
The scoop like structure highlighted in this pic takes in water for non-radioactive reactor cooling circuit. Just like the Typhoon they had natural circulation reactors which made them a lot quieter than the LA which didnt have such a reactor.
This is the OK-300 propulsor used for ultra-quiet running or during emergencies. They were connected to the batteries and were run by quieter electric motors which further reduced their acoustic signature when used.
Just like the Typhoon, they also had retractable communications buoy, the door for which has been marked in the pic above.
SOKS sensor on the sail
SOKS sensor on the hull.
SOKS is the ace that the Russians had up their sleeves. All American subs had superior acoustic signature compared to Russian ones before Akulas. Thus the Russians developed the SOKS system which relied on a submarine’s wake to detect it. A wake would generally last for several hours and wakes for different subs were different. Victors, Akulas and Sierras all had these and have reportedly trialed Ohios(claimed to be the most undetectable subs) for hours at a stretch by using these. This system allowed the sub to stay out side the other sub’s sonar range while maintaining contact with it. Russians also had wake homing torpedoes to kill subs without using sonar. The Americans simply had no means to counter this capability. An Akula generally has the 10 point sensor on its sail and the 3 points on the top part of hull and several other sensors in other parts below the water line. Unlike American subs, Russian subs were more streamlined as they tried to make their own subs the least detectable to such sensors, but the Americans didnt have any thing comparable.
This is K-295 under construction, we can see the six small hatches which are used for counter measures, holding 2 per tube thus 12 counter measures. These produced noise of its host submarine at higher levels than the sub was making thus taking the enemy sub/torpedo away from its host. Americans are said to have the MOSS which is Mobile Submarine Simulator which did the same thing but was larger.
This is a pic of K-152 under construction which is presently leased to the Indian navy and has been named as INS Chakra. We can see that the leading edge has a cavity, well this cavity houses a smaller cylindrical array which is one of the several seen on Akulas. On the other hand, INS Chakra doesnt have either SOKS or the counter measure tubes as she was modified for export. On the other hand, she is certainly the longest of the Akulas and heaviest too which makes her quieter than her sisters, as the Russians usually increased the length to add a quieter propulsion system. Another difference she has, is that she features 8x533mm tubes instead of the usual 4x533mm and 4x650mm ones.
In this pic of INS Chakra we can see the small bump in the sail, like all new gen Soviet subs she also has a rescue pod for her entire crew.
Irbis, the last of the incomplete Akulas is seen in this pic. As per some sources India and Russia are negotiating for her completion and lease to India, which will give em two of the best SSNs operating in Asian waters.
Two of the incomplete Akulas and one damaged Akula were used to complete Boreis. This is K-551 and the arrangement of counter measure tubes, torpedo tubes and the torpedo loading hatch clearly show that the bow section is of an Akula.
Here is an early Akula undergoing sea trials, she had 6 decoy tubes but lacks the SOKS sensors on the sail and the hull above the water line.
Last but not the least the designer of the Akula class
Georgiy Nikolayevich Chernishov, he was the chief designer of the Victors as well which were designated as Project 671. Looks like they simply flipped the “6” into “9” to name Akulas, another thing is that the Russian name for Akula is Shchuka-B where as Victors are Shchuka and we all know that Akulas are externally very similar to Victors. Looks like he just carried forward his ideas into the new design.
Pictures taken from: http://imgur.com/a/pZCb0
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