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-   -   Indian Navy - A Shipbuilders Navy: INS Nilgiri, INS Godavari & INS Brahmaputra (https://www.team-bhp.com/forum/commercial-vehicles/161202-indian-navy-shipbuilders-navy-ins-nilgiri-ins-godavari-ins-brahmaputra-3.html)

Peter, the 44,000 odd tonne figure is the full load displacement and the 33,440 tonne figure is the standard displacement. The difference is the weight of ships fuel & boiler feed water. Those are the book definitions. Warship displacement figures are always estimates and Navies by habit obfuscate about whether the difference also includes weight of ammunition and aviation fuel or not. Further whether the ability to carry an over load of fuel is within or outside the full load displacement. Hope this helps in more cheerful confusion. A fine photo from this year's Navy calendar of both carriers in company. A sight we may not see for long as the old lady INS Viraat is 55 years old now. It is a testimony to the Navy's maintenance engineers that they have nursed her along this far.

Why can you only launch 2 on a ramp? I would have thought you can launch as many as you like, providing you leave enough separation?

Don't you just line up the aircraft and get them to take off one after another on a ramp?

Jeroen

And a mighty one at that ;)

Lining up the aircraft one after another and getting them to take off is not possible. When one aircraft is on the take off roll, you cannot have an aircraft waiting behind it because of the jet blast of the aircraft in front. The jet exhaust at high temperatures will adversely affect the aerofoil and also will affect the air intake of the engines.

Some aircraft carriers have something called a "Jet Blast Deflectors". A JBD is a plate like object, wider than the width of the take off strip and is flushed to the deck in normal cases. It is positioned at the beginning of the take off strip, between the line up point and the take off point.



It is sprung out with a pivoting motion and provides a deflection surface to the jet blast (as the name suggests). After the aircraft takes off, it is operated to go flushed into the deck again so that the next aircraft can taxi onto the take off point.



If you have a JBD on the carrier deck, you can have an aircraft lined up behind. Some US carriers has them; while the Indian Carriers don't.

However, the jet blast is the only limit for line up of the aircraft. The next aircraft can line up as soon as the previous one has left the ski-jump. The ramp does not in anyway leave a limitation to the number of subsequent launches in one go. Where as the catapult might have a limitation due to the heat generated on the system.

Thanks, i did not mean lining up literally. If i look at these pictures there is plenty desk space where they can park at least ten jets. Have everybody engines running and take off checks done and they should be able to taxi in take off position one after the other pretty quickly.

There is a notable difference on how these ramps are used. They were invented and pioneered by the British. Their Harrier could take off vertically, but that came at a huge fuel penalty, decreasing range considerably. Enter the ramp. The harrier will direct its four rotating nozzles rearwards to accelerate down the deck, when it hits the ramp the nozzles are pointed at an angle down and back, providing thrust and lift. Only when the Harrier accelerates enough for the wings to proved lift can the nozzles be pointed full rear again. Other aircrafts, without the swing nozzles need brute force to accelerate them to sufficient speed for the wings to provide lift as soon as they leave the ramp.

All military jets going full blast go through their fuel extremely fast. Most planes launched from a carrier will do an air to air refuel immediately after launch before they begin their mission. So I think there a few more parameters then just weight to thrust that will determine the design of a carrier.

I have had the pleasure of being on the USS Enterprise, many years ago, whilstthey were conducting flight operations, both day and night. Absolutely amazing.

Jeroen

That sounds awesome. I am green with envy.clap:

Dear Jeroen,

Thank you for this question from a fellow aviation enthusiast. This question is probably on the minds of other readers as well. Dhanushmenon has given an informative & illustrative reply for everyone's benefit.

What I said in post number #27 is that from a ramp a carrier can launch 2 aircraft simultaneously ie in quick succession. I did not say or mean that only two launches can be done. As you correctly point out with adequate separation the next two aircraft can then be launched and so on. What follows below is material you already know. Putting it down for the benefit of other non-Naval readers.



Photo shows a INS Vikramaditya with its two take off points (blue arrow) that can be used almost simultaneously. As it doesn’t have jet deflectors the next two aircraft readying for take-off would be waiting to the right a little behind.



Photo showing one Harrier on the take off run while the other has just turned in at the aft waiting for the flight deck to clear. A Harrier jump jet is the smallest and most 'short take-off capable' aircraft regularly flown off a carrier ramp. It needs a minimum of 180 metres to reach a speed adequate for the ramp's acceleration to help it take off especially if at maximum take-off weight. The run down this 180 metres (or more if the carrier length allows it) takes about 5 seconds. As the aircraft needs the full length of the carrier it starts from the far aft end as shown in the photo above. The second aircraft positions itself, the ship turns into the wind, aircraft runs up to full throttle, gets the all clear signal from the deck officer and off it goes. So from the moment the first aircraft positioned itself on the take-off line in about 45 seconds you get two aircraft off. Then the next two standing on the right start lining up.



In the photo here we see two US Navy aircraft, F-18 Hornets in this case, taking off simultaneously one from the waist steam catapult and the other from the bow steam catapult. As there are 4 steam catapults 4 aircraft get launched in less than a minute.



The US carriers carry 4 catapults two in the bow and two in the waist position. The photo above, from one of my ancient books, shows 4 aircraft ready to launch on the 4 catapults. They will go two at a time and 30 seconds later another two. The next four ready behind them will then get hooked for launch, build up steam (in the catapult) and go.

Brilliant thread. Hats off to Mr. Narayan. Was always confused wrt the classification of warships. Thanks for clearing it.

The Challenges of Indigenization on the Nilgiri Project

In today's day and age when Foreign Direct Investment flows in freely it is hard to perceive the difficulties we faced as a nation in getting basic license production of important pieces of machinery even after signing a large contract with the British Government to build 6 Leander class frigates. I am penning these down for the younger generation on Team BHP and other readers who started their careers after 1991 to learn about how things were in earlier years.

In Photo #F in the main article it is explained how the British reneged on supplying the license to assemble and (later) build the radar suite. And how the Dutch stepped in and built a long term relationship. The story did not end there. The transmission of these ships was through a David Brown Engineering gear box. Naval gear boxes are not only mechanical marvels they are also a work of art and metallurgy gearing down from 10,000 RPM steam turbine to a 150 RPM marine propeller. David Brown point blank refused to sell us the license rights for assembly and manufacture. They assumed we will have no choice but to buy it from them and also save them the bother of transferring know how to a third world country. Interestingly Walchand Nagar Industries who had a technical collaboration with a Swiss company called MAAG said 'hey our collaborators can make these transmission units and they will sell the know-how too'. Walchandnagar were known more for production of sugar and not gearboxes - understandably the Navy was nervous as hell. But necessity is the mother of invention and we plunged ahead on what was a high risk path. The British said we cannot guarantee the mating of your Swiss gearbox to our turbines at one end or the propeller at the other. The Swiss proved as good as their word. There were few hiccups in the trials but they stayed the course with us and produced perfectly mated gearboxes.

Vickers, UK were the suppliers of the gun, some of the weapons, the turbines, the boilers and more. They were unduly skeptical that these ships will ever get built in a backward country like India and their Chairman said so in so many words to admiral BA Samson but Vickers were happy to sign the contract and collect the fee all the same! In fact their Managing Director Sir Issac Eric came for the final trials convinced that Nilgiri would fail them and he had kept a team of British engineers on standby with air tickets to fly down, from the UK, on this expected 'failure of final tests'. One test is to race the ship forward at full power and full speed and then suddenly switch to full aft ie reverse by reversing the turbines. This puts the ultimate strain on all the machinery and the hull and is conducted but once in a ship's lifetime in pre-commissioning tests. Fortunately they had to cancel their tickets as the tests went off without a hitch.

We learnt a lot from the British and these anecdotes are not meant to be prejudicial but the world was a little different back then in 1967.

Take a bow V.Narayan sirclap:.What a fantastic thread that provides the detailed history of our navy ships. This thread deserves something more than 5 stars.Just out of curiosity, do you have the details of the total count of vessels that is operational in our navy (Air Craft carrier, submarines etc.,)

This by far is a very good definition of the roles performed by each class -
Thanks to Bharat-rakshak.com

Corvettes - the ultimate single role ship lying between 1000 to 2500 tons. Usually are restricted to coastal or littoral waters since they have limited long range capabilities. Examples of a typical corvette are Project 25 and 25A of the Indian Navy. These are skewed towards surface warfare with point defense anti air capabilities. Now interesting are the Project 28 ASW corvettes since these ships are the extreme end of the weight limit (2500 tons) yet are single role ASW vessels.

Frigates - Typically single role ships lighter than destroyers, but heavier than corvettes. Frigates were made for Anti-Submarine Warfare (primary) and escort roles (merchant shipping) or at least that was the rationale. Also navies needed ships which had longer range than corvettes. Some had Medium Range air defenses added as well to protect itself and the escorted vessels. Though in modern times because of lighter and more capable systems it is getting increasingly difficult to judge what is a frigate and what is a destroyer. Another yardstick was Tonnage frigates typically being defined as lying between 2500 tons to 5000 tons (give or take a few 100) but again morden frigates are easily heavier. Examples are the Spanish F100 Alvaro de Bazan Class Frigate or the French Horizon Class. Though again in the modern navy frigates are typically classified for political reasons than capability ones. For example the Project 17A being planned for the Indian Navy and Australian Navies Air Defense Destroyer Project which is taking a ship the originating country calls a frigate and classifying them as destroyers.

Destroyers - Ultimate multi-role warships of any Navy. The destroyer has evolved from WW1 and WW2 fleet escort vessels (I mean fleet as in Battle Fleet not merchant shipping) these ships were shields and scouts for Battleships and Battle Cruisers and always acted in Squads. Though as time went by and technology and missiles got added in. Destroyer roles changed to the current 6000 ton plus ships with significant Anti-Air, Surface and Sub-surface capabilities (i.e. multi-role). Typical examples - American DDG - 52 Arleigh Burkes, Indian Navy - Delhi and Kolkata Class, Russian Navy Udaloy and Sovremenny-class Destroyers.
Though navies still try and give more weightage to a certain role. In my humble opinion this is now a publicity gimmick than reflection of actual capabilities. Udaloys are classified as large anti-submarine ships. Though they are equally capable on the surface and have decent short range anti air capabilities.

Cruisers - As the name itself reveals in olden times these ships were any ship that were expected to perform their roles by their own merry self. In WW2 that meant a ship larger than destroyers to mount significant Anti-Surface Guns and Anti-Air capability. In the modern times except for US and Russia no other Navy even has cruisers since the Destroyers have taken up most roles. Again if you look at the weight capabilities cruisers would be 10000 tons and upwards. Cruisers are again typically multi-role. In fact if you really go by the book meaning other classes would not be defined as multi-role only crusiers would be.

Dear AMDB9, thank you for reading the thread and for your kind words. If you can wait till the weekend I can put together this data for you with photos:) and some commentary along with links where you could read more.
BHPians who serve or have served in the Navy will undoubtedly know a lot more but I suspect it may not be kosher for them to write on this question.

For all who are in cochin or who may be travelling here soon. Please ensure that you do not miss the rare opportunity of seeing all the three Aircraft Carriers together.
INS Vikramaditya and INS Viraat are here in Cochin for a few days. Training If I am not wrong. And in fact you can see the INS VIkrant on the Cochin Shipyard.

Drive through Venduruthy Bridge near MG Road for this awesome spectacle. I think there a good number of other ships, like corvettes, supply ships etc accompanying the same also being berthed here at INS Dhronacharya. Our Training command.

Cheers ! Let em see whether I can catch a glimpse of these 3 ladies.

Any chance of pictures? How far is the construction progressed?

Cochin Shipyard is a Photography Prohibited Area. Even there are sign boards mentioning the same on nearby hotels, roads etc.

But I may be able to get pics of the vessels docked at the Naval Base. Not sure. I shall try. But for sure, will have more coming up about INS Vikramaditya and INS Viraat coming in local media.

The super structure (Guess thats what it is called) is done. The ship is in its full shape and the bridge, control centres etc which is the tall structure on the ship is all done. The take off ramp is clearly visible. I think since its due for trials in a year or two. Its only left with the mechanical parts, cosmetics, and off course weapon systems, controls, and so on.

Current active Fleet of the Indian Navy


1 Nuclear powered Attack submarine

13 Diesel-Electric Submarines

2 Aircraft Carriers

9 Destroyers

15 Frigates

25 Corvettes

6 Large Amphibious Warfare Ships

10 Landing Ships/Crafts

8 Minesweepers

10 Ocean going Patrol Ships

30 Patrol Boats

4 Underway Replenishment Ships

9 Survey & Research Ships


Naval Aviation Strength (all approximations)

~40 to 50 Fast Combat Aircraft (Mig-29K & Harriers)

~19 Long Range Maritime Patrol Aircraft (Anti-Submarine & Anti-Ship)

~35 Coastal Patrol Aircraft (Mainly Dornier Do228)

~50 Anti-Submarine Helicopters

~15 Airborne Early Warning Helicopters

~75 Transport, Utility and Patrol Helicopters


I have not included training ships, support vessels and utility vessels. When listing warships submarines always come first. They are recognized as the 'Queen' of the ocean's chess board. Photos below of a few warships with annotations of interest.