[sgiitk]

Our subs are mostly Russian on bared on their designs. In case of the latter expect the Russians to supply a lot of sub-systems. Now the US wants to clamp down on this. I do not think India will kowtow, but still fingers crossed.

[Jeroen]

Originally Posted by Sutripta

How are propellers tested for their acoustic characteristics?

Would be interested to hear. The problem is one of size I imagine.

Of course, they will do endless computer simulations. But at the end of the day, probably the only way to test it is on the sub in actual conditions. It's of course not just the propellor that determines the accoustic charactistics, but also the shape/material of the hull, rudders etc. Maybe even to some extend the water properties itself as well?

I have seen testing on propellors for cavitation in research laborotry. That is on scaled down models of the propellors and hull. Although scaling down does introduce additional elements to compensate for compared to full scale, apperently it was good enough and made economic sense for quite a while to do in this fashion.

There is a Dutch research institue specializing in this:

http://www.marin.nl/web/Ships-Struct...Submarines.htm

Model testing is/has been common for merchant ships as well

https://www.youtube.com/watch?v=qu3jvRX1UaE

Would be interested to hear from someone a little bit more in the know, but sub-propellor tend to be a bit of hush-hush topic, obviously.

Some basic reading for those who like to get a feel for what it takes to design a submarine propellor:
http://www.marinepropulsors.com/proc...0Submarine.pdf

Jeroen

[Sutripta]

^^^
That Youtube video needs an epilepsy warning!

Would be interested in knowing if the Soviets did things differently. (And no, 'getting' milling machines from Japan does not diminish their design capabilities).

Knew a person in HP printer section whose job was to go through different enclosure designs to predict/ determine how noisy a printer would be (important in an office environment), before anything was built.

Regards
Sutripta

[Jeroen]

Originally Posted by Sutripta

Knew a person in HP printer section whose job was to go through different enclosure designs to predict/ determine how noisy a printer would be (important in an office environment), before anything was built.

It is important. The more you can figure out in the design phase the better.

I remember as part of my graduation of Naval College I did a thesis on noise and vibration prediction during ship design. Once a ship is build it is very difficult or at least very expensive to make any fundamental changes. So understanding what vibration and noise level you are going to get and how effective certain design measure could be, was key!

Jeroen

[V.Narayan]

Type 1500 submarines to be refitted and upgraded by ThyssenKrupp, Germany

//economictimes.indiatimes.com/articleshow/65967874.cms?utm_source=contentofinterest&utm_medi um=text&utm_campaign=cppst

ThyssenKrupp Marine Systems has bagged a Rs 410 crore contract from state-run warship maker Mazagaon Docks Shipbuilders (MDL) to upgrade the Indian Navy's Shishumar class non-nuclear submarine, INS Shishumar. This will be a Medium Refit and Life Certification (MRLC) contract that will commence from October with the upgradation expected to be completed by 2021.The upgrade will extend the operational life of the submarine by 10 years.

The announcement is part of the Indian Navy's plan of overhauling the four HDW Class 209 Type 1500 diesel-electric attack Shishumar submarines that entered service in the late 1980s and early 1990s. The Type 1500 are also being upgraded with American UGM-84 Harpoon anti-ship missiles that are launched underwater from the 533mm torpedo tubes. The Harpoons with the IN are used also on the P-8I long range maritime patrol aircraft and the Sepecat Jaguars IM. While accurate data is hard to come by the IN Harpoons are believed to be Block II with a range in the region of 150 nautical miles (~280 kms). That is realistically speaking at the outer limit of being very sure the contact is a baddie.

The four Type 1500s have rendered yeoman service to the Indian Navy. I only wish we had continued building them in the 1990s instead stopping after four vessels.

INS Shishumar coming alongside on a visit to Oman. A Delhi class destroyer in the background. India and Oman share warm and close ties.


The Harpoon UGM-84 in flight. A sea skimmer.


Periscope view of a UGM-84 Harpoon being fired from the torpedo tube of a submerged submarine.

[ads11]

Slightly off topic but I have an absolute treat for you guys. Stumbled across this excellent 2 part series on the BBC. You'll need an account and you'll need a VPN set to the UK to watch it on iPlayer. But it's well worth it. Given that we operate subs of Russian vintage it gives you a fascinating insight. Also it has some great stories from the Cold War, one of which I guarantee will be V Narayan's favourite I'm sure.
https://www.bbc.co.uk/iplayer/episod...now-your-enemy

PS: I tried to find an open source/bootleg of this on a free link but have no luck.
I was recently told the Opera browser has VPN built in and someone was able to watch it using that so that would be my recommendation.

Also rather fortuitously this documentary definitely gives you an insight into the paths where the Soviet way of doing things would diverge.

[V.Narayan]

Indian Navy Acquires Deep Submarine Rescue Capabilities

Filling a long felt need for a submarine rescue capability, the Indian Navy has just formally inducted its first deep submergence rescue vehicle (DSRV). Built by the U.K’s James Fisher & Sons, the vessel — the first of two — finally gives the navy the ability to rapidly attempt rescue of personnel in submarines in distress. With this India has joined a select group of countries that have the capability to locate and rescue "distressed submarines".

The first DSRV is located in Mumbai. The second DSRV is expected to be inducted at Visakhapatnam in 2019. The DSRV is air transportable in the large IAF cargo lifters such as the C-17.

The DSRV, which is operated by a crew of three, can rescue 14 from a disabled submarine at one time. On 15 Oct 2018, the DSRV carried out under water mating with a bottomed submarine, at over 300 feet depth. On successful mating the DSRV opened its hatches and the submarine hatches and carried out transfer of personnel from the submarine to the DSRV. It is believed that testing has been done down to 650 metres. At 650 metres the pressure on the hull is about 66 atmospheres.

Read more at :
https://www.livefistdefence.com/2018...apability.html
https://www.ndtv.com/india-news/indi...lities-1931648

Photo: Indian Defence Update
Photo illustrates the DSRV's built by James Fischer & Co, UK. The one built for the IN may or may not be like this.

[ads11]

This is indeed great news. Not only does it allow IN sailors stuck in a stricken boat the prospect of salvation without having to wait on an international response being mustered but I think this might turn out to be an extremely handy soft power tool. As far as I'm aware, there aren't any other nearby countries that have DSRV's. However nearby countries do happen to operate submarines. Should there ever be an unfortunate situation for a submarine in the vicinity of the Indian Ocean Region, well India would be presented with an opportunity to score some very easy international goodwill points. Obviously no one wishes it came to that but this little guy could do far more good than just the mission it was designed for. I hope it's looked after well.

I imagine one each will be stationed in eastern and western sectors.

[V.Narayan]

INS Arihant completes India's first SSBN deterrent patrol

https://www.ndtv.com/india-news/ins-...m-modi-1943124

India's first nuclear powered ballistic missile armed submarine has completed its first underwater nuclear deterrent patrol. A landmark day for the Indian Naval submarine fraternity. With this India becomes the sixth nation to conduct nuclear armed deterrent submarine patrols. The others are USA, Russia, China, UK & France.

INS Arihant represents the successful marriage of four different technologies - submarine hull, nuclear propulsion and associated steam turbines, ballistic missile with a workable accuracy and a nuclear warhead.

Approximate details in the public domain are:

Displacement, dived: ~6000 tonnes
Length: ~110 metres
Propulsion: pressurized water cooled nuclear steam turbines
Torpedo tubes: 6
Missile silos: 12 shorter ranged K-15 [750 kms] or 4 longer ranged K-4 [3500 kms]. The K-15 is operational. The K-4 is under development.
Speed diving depth are not known and can only be guessed at.
Endurance: Limited by crew fatigue and food. Typically 60 to 90 days.

For lovers of Naval history I repeat a factoid also quoted elsewhere in one of my threads. In the early 1980s Indira Gandhi asked the Navy to do a study on what it would take to develop our own nuclear submarine. This was when we had not even built a submarine ever let alone a nuclear one. Late Vice Admiral Subimal Mukherjee, then the Vice Chief did an honest study and explained it will take us 35 years at least and Madame Gandhi said, "then Admiral we have no time to lose. Lets start right away!" It takes a leader of stature to think of the next generation. And today INS Arihant, our first indigenously designed & built nuclear submarine, has completed its first patrol. Mukherjee's assessment was spot on.

Jai Hind.

Photo Source: India Defence Review
K-15 submarine launched ballistic missile.

PS: I haven't posted a photo as no official photo of Arihant has been released by the IN. The photo's you see in newspapers or news websites are of all kinds of submarines including conventional diesel-electric ones! An artists rendition can be seen on post #65

[Maveryq]

A query from a submarine noob.



The Akula Class submarine has a towed array pod on its tail mast. Does the INS Arihant which has been designed domestically have a similar sonar?



The image that was used by the PIB did not show any pod on the tail mast of the Arihant.


Images sourced from the internet.

[V.Narayan]

Originally Posted by Maveryq

The Akula Class submarine has a towed array pod on its tail mast. Does the INS Arihant which has been designed domestically have a similar sonar?

A towed array is a sensor typical for a SSN i.e. an attack submarine or a hunter-killer which is what INS Chakra is. As INS Arihant is a SSBN whose job is silent undetected deterrence and not getting into hunter-killer mode {except in self defence} it probably does not carry a towed array - but we don't know as data is classified. INS Chakra's pod is a neat Russian way to stow the towed array when not in use. Its position reduces the chance of the array getting entangled with the aft mounted propeller. Towed array's can also be carried on the top of the hull clipped on length wise.

You obviously know this but let me add it here for the benefit of other readers. That pod is a container for a towed array sonar. A towed array sonar is like a giant string of hydrophones{listening devices} towed behind a submarine {or a ship} for several hundreds of metres {or even a few kilometres}and surveying the area by passively listening. By being towed some distance behind the sub the array enjoys the ability to pick up faint signals with minimal 'noise' from the vessels own propulsion.

Images sourced from the internet.

This may or may not be a picture of INS Arihant. I don't know. A lot of incorrect photos parade around on the internet on this boat. Didn't know PIB has released photos.

[Maveryq]

Originally Posted by V.Narayan

This may or may not be a picture of INS Arihant. I don't know. A lot of incorrect photos parade around on the internet on this boat. Didn't know PIB has released photos.

Sir, thank you for the clarification. I took that picture as the one for INS Arihant because the picture that Mr Modi released on his Twitter account had that as the back ground in the TV screen. Please see the images below from Mr Modi's Twitter timeline when he was felicitating the sub-team after their return from the patrol.

It might well be that these are not the INS Arihant pictures and they used a generic one for representation purposes.

And you are correct in stating that multiple incorrect photos are being paraded around. Most of the reports seem to have the Akula Class INS Chakra as a proxy for the INS Arihant.

Another thing that I noticed was that the INS Chakra / Nerpa is an Akula class SSN, while INS Arihant is an SSBN. Why did India lease an SSN to familiarise its Navy with SSBN operations?

Given that India also has the P-8 Poseidon aircraft, I wonder if the INS Arihant and the P-8 might have played "catch me if you can" games in the oceans. That would be interesting, though almost certainly classified.

Picture source from Mr Modi's Twitter account.

[V.Narayan]

Originally Posted by Maveryq

Another thing that I noticed was that the INS Chakra / Nerpa is an Akula class SSN, while INS Arihant is an SSBN. Why did India lease an SSN to familiarise its Navy with SSBN operations?

For purposes of training and developing operating protocols for nuclear power the key alphabet is N and not B. Also one nation leasing a nuclear powered submarine to another is a highly unusual occurrence - globally it has happened only twice - both between Russia & India twice. Even USA did not lease its subs to the UK their bosom allies {though they did sell a reactor & full propulsion set for the first British SSN}. Russia would have been in contravention of its various SALT treaties if it leased an SSBN albeit without the missiles. And on a practical level a SSN is more multi-role than a SSBN.

[Maveryq]

Originally Posted by V.Narayan

And on a practical level a SSN is more multi-role than a SSBN.

Thank you Sir, and your opinion is correct. Leasing an SSN would also probably help to build operational protocols for the IN.


Since you had queried about the INS Arihant pictures, here is another picture purportedly of the INS Arihant by The Hindu.


Picture Source: The Hindu article on INS Aridaman /Arighat

[V.Narayan]

Originally Posted by Maveryq

Since you had queried about the INS Arihant pictures, here is another picture purportedly of the INS Arihant by The Hindu.

The picture posted by you is correct.
Only one country has an SSBN and also operates the Alouette III helicopter.
Nice silhouette with its gently sloping streamlined fairing.
Thanks.