INS Vikrant Aircraft Carrier (IAC)

nirranj

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I wish If I have two billions I will use it to fund a second carrier.. with some new techs... We should not stop here... follow on ships in this class is necessary and making Kochi as our Carrier building hub is also necessary...
 

SajeevJino

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why is this in a bow shape, unlike other ships some bulb like structure..!!!!

the vikky is fitted with Ski Jump where Viraat comes with Ski Jump

also the Vikky's bow shape is very useful to broke the ice
 

Kunal Biswas

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It is call ship bow bulb or bulbous bow..





The strongest resistance any vessel faces in standard operations comes from displacement as the hull moves through water. Waves that climb the bow are water being pushed aside faster than it can move away. It takes a lot of power to overcome the viscosity and mass of water and that means burning fuel which adds to costs.

A bulbous bow is an extension of the hull just below the waterline. It has many subtle shape variations but it's basically a rounded front portion that flares out slightly as it blends into the traditional displacement hull construction. These forward protrusions are about twice as long as the width of the base and they would usually not extend forward past the top of the bow. The basic principal is to create a low pressure zone to eliminate the bow wave and reduce drag.

First appearing on the USS Delaware in 1910, the bulbous bow was a controversial design of U.S. Navy Ship Architect David W. Taylor.

Much of the controversy disappeared ten years later when passenger ships began exploiting the design to increase speeds.

Hulls built with bulbous bow sections are common today. Under certain conditions this type of design is very efficient at redirecting forces of hydrodynamic resistance and drag.

Good Conditions for Bulbous Bows

The design of a ship with a bulbous bow is discussed in many textbooks and technical articles. It is often referred to as a theory or an art, which is a short way of saying nobody is 100 percent sure of what they are writing. There are details to be worked out but modern builders have proprietary ways of analyzing and integrating all hydrodynamic aspects of their hulls and these methods are strict secrets.

A bulbous bow works best under certain conditions and good design gives efficiency gains throughout the range of these factors.

Speed – At low speeds a bulbous bow will trap water above the bulb without forming a low pressure zone to cancel the bow wave. This leads to increased drag and loss of efficiency. Each design has what is known as most efficient hull speed, or often just hull speed. This term refers to the speed where the shape of the hull is acting on the water is such a way to produce the minimum possible drag.

This ideal hull speed might not be the top speed of a ship because at some point the lower pressure zone created by the bow features becomes larger than necessary. A zone of lower pressure water that is larger than the hull is inefficient and leads to reduced rudder response.

Ideally the cone of lower pressure water will collapse just before the props. This gives the prop blades something to push against and limits cavitation at the props and rudder. Cavitation will lead to reduced efficiency of props, sluggish steering, and excessive wear of hull and drive components.

Size – Vessels under 49 feet (15 m) do not have enough wetted area to take advantage of a bulbous bow. The amount of drag on a hull is related to its wetted area. The structure of the bulb also increases drag and at a certain point the benefits shrink to zero. Conversely, larger ships with a high proportion of waterline to frontal area use the bulbous bow most effectively.

Bad Conditions for Bulbous Bows

Rough Seas – While a traditional hull rises with the wave, a hull with a bulbous bow can dig in even if it is designed to lift the bow under normal conditions. The issue of trim is one of the most deeply dividing aspects of bow design among naval architects. There is also a huge psychological aspect among crews who perceive this bow design as dangerous in storms. There is some truth that these bows dig into wave faces but there is little proof that it is more dangerous than traditional designs.

Ice – Some ice breaking ships do have a special shape of bulbous bow that is heavily reinforced. Most bulbous bows are prone to damage since they are the first point of contact with an obstacle.

In addition to ice, large debris and fixed objects like dock faces can damage these extended underwater bows.

================



IAC-1 has the same, It just camera is not low enough to the photo, or the bulb is not attached, We will see it soon..

why is this in a bow shape, unlike other ships some bulb like structure..!!!!

the vikky is fitted with Ski Jump where Viraat comes with Ski Jump

also the Vikky's bow shape is very useful to broke the ice
 

arnabmit

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‘Designing aircraft carrier Vikarant was complex, challenging’ | idrw.org

SOURCE: PTI

Ahead of the launch of its first indigenous aircraft carrier at Kochi on August 12, Directorate of Naval Design today termed it as one of its most "complex and challenging" works which would be considered as a key success in Indian Navy's indigenisation programme.

Director General, Naval Design, Rear Admiral AK Saxena said the 37,500 tonne carrier's design and capacity went through many changes and also suffered setbacks, caused by fund constraint, before "Mig 29K came on the horizon", prompting the directorate to build a carrier big and efficient enough to handle it.

"It took us seven to eight years to design it," he said, adding it would have over 1400-member crew.

Defence Minister A K Antony's wife Elizabeth Antony will launch the carrier, to be named Vikrant, capable of handling 30-odd fighter aircraft.

The warship would be able to join duty in 2018. Its launch would catapult India to a select group of four countries capable of manufacturing and operating a 40,000 tonne carrier.
 

A chauhan

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Indigenous aircraft carrier made of special steel

Published August 6, 2013 | By admin
SOURCE: IANS

Over 24,000 tonne of specially designed steel capable of withstanding "high impact load shock" has gone into the construction of India's first indigenous aircraft carrier, officials said Monday.

Commodore Saibal Sen, additional principal director, Naval Design, said here that DMR-249A and DMR-249B were among the qualities of steel that have been developed in the country and used in the aircraft carrier, which will be launched at Kochi Aug 12.
He said while DMR-249A was at least twice in strength than normal steel, DMR 249B was thrice as tough.

The high-end steel qualities for warships were developed following research efforts of Defence Metallurgical Research Laboratory (DMRL) and Naval Materials Research Laboratory (NMRL) in association with Steel Authority of India Limited (SAIL), a public sector company.

DMRL and NMRL are both organisations of Defence Research and Development Organisation.

Sen said that the steel qualities had been tested for their strength at minus 60 degrees.

He said about 27,000 tonnes of steel will be used in construction of the aircraft carrier and would cost about Rs 500 crore.

Sen said that the development of the specialised quality steel was of national and strategic importance and would have rip-offs in the coming years.

He said there was possibility of such steel being used in construction of civilian ships also.

SAIL chairman CS Verma said the organisation was laying thrust on "value added products" as part of its modernisation efforts.

He said total requirement of steel for defence sector was about 1,20,000 tonne per annum and SAIL was providing over 75 percent of the demand.

He said the navy's needs of steel were also being largely met by SAIL.

Sen said the navy had to maintain a large inventory of various grades of steel to meet requirements and difficulties were being faced in procuring them.

"Due to these reasons, the navy decided to rationalise these steels to AB class with superior properties," he said.

The aircraft carrier is being built at Cochin Shipyard Limited. After its launch, it will be redocked at Cochin Shipyard for erecting the island superstructure and remaining underwater work.

Indigenous aircraft carrier made of special steel | idrw.org
 

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