Thursday, April 29, 2010

“The P-17 frigates, heralds a paradigm shift in the design”

                Interview with Rear Admiral KN Vaidyanathan 
                                                (Director General Naval Design)

Shivalik, the first Ship of the P-17 Class, appears different from earlier designs of IN ships. What are the major new design features of this class of ships? Please elaborate on stealth features in particular and how were they achieved during design and construction and during acquisition of equipment from the industry?
Shivalik, the first of class of the P-17 frigates, heralds a paradigm shift in the design of future surface combatants for the Indian navy. While the sleek and stealthy appearance of Shivalik, sets her as a class apart from earlier indigenous designs, the ship embodies several new design features to give her much improved operational capabilities. “Stealth” has been a major thrust area from the early stages of the design. Apart from this, the design embodies several new concepts for improved survivability, seakeeping, ship handling and on-board habitability. The watertight subdivision of the hull meets the most stringent damaged stability requirements and the distributed power supply systems using Energy Distribution Centres (EDCs) has allowed zoning in the Power Generation & Distribution (PGD). The incorporation of the TACS (Total Atmosphere Control System) for the ship’s air conditioning and ventilation system, which features considerably reduced number of external air induction/exhaust terminals, gives her a very user friendly citadel which is easy to operate and maintain. This gives the additional benefit of uncluttered exteriors of the ship which has 


significantly reduced the Radar Cross section (RCS) of Shivalik. The hull form with carefully crafted hull sections and load water plane, gives the vessel excellent sea keeping qualities together with very good propulsion performance as a result of low shaft rake and very low appendages resistance. The relatively large rudders give the ship excellent manoeuvring performance as has been borne out by the ship trials. Use of modular accommodation has considerably improved on board habitability. The design of Shivalik evolved with considerable focus on reducing the ship signatures. Primary focus was on reducing the RCS, Infrared signatures and the Radiated underwater noise of the ship.
RCS: The hull form features flared main hull and sloped full beam superstructure to considerably reduce specular reflections. Special care was taken to avoid dihedral and trihedral corners which cause multiple radar scattering. The boat deck has been concealed behind radar suppression screens. The Gun turret in the foxle has a stealth canopy and the flush deck Vertical Launch Missile (VLMs) for the Surface to Surface Missiles (SSMs) have been conducive to reduced RCS. The helo hangar has sloped shutters and flush deck rails for helo traversing gear. The hull form and superstructure was evolved iteratively by extensive 3D CAD modelling and continuous RCS signature evaluation using specialist signature evaluation software.
IR Signature Reduction: The infrared signature reduction is achieved by using Eductor Diffuser IR suppression devices for the Gas turbine and the diesel engines. Besides exhaust gas cooling, hot metal cooling is achieved to afford good look-down protection from hostile IR sensors. The engine room ventilation with sea water coolers and acoustic enclosures for DAs help to reduce hull contrast temperatures.

Radiated noise: Acoustic studies were undertaken from early design stages by modelling the structure and airborne noise characteristics of machinery equipment to predict the underwater radiated noise.  The results of these studies helped drive a balanced approach to noise reduction guiding the selection of machinery configuration and mounting arrangements with specifications for the structure borne vibrations and air borne noise which were included in the procurement orders of the equipment. Acoustic signatures were verified during factory acceptance trials, before clearing the noise critical machinery for installation onboard ship. The sea water suctions are arranged from carefully designed sea chests, to avoid radiation of fluid borne noises due to pump impulses.

Procuring machinery and equipment meeting the stringent vibration and airborne noise specifications was quite a challenge. However, I must say, the Indian industry has come some way to meet the requirements, but there is much road ahead to cover.
What are the major new systems in the Shivalik class? What are the new features in terms of the layouts on the ship?
Shivalik is the first IN ship to have a Combined Diesel or Gas Turbine (CODOG) propulsion plant. This propulsion configuration combines the compact high power/speed benefits of the gas turbines with the long endurance advantage of the diesel propulsion. The twin shaft arrangement features relatively large, slow running propellers which, while driving the ship efficiently at the top speed, also have high cavitation inception speeds compared with earlier designs. This feature of the propeller compliments the low noise features of the machinery to provide silent speed regimes of operation up to cruise speeds. The Integrated Machinery Control System (IMCS) features multifunction displays with distributed Remote Terminal Units (RTUs) riding on a dual redundant Gigabit Ethernet data bus to monitor and control the ship’s propulsion and auxiliary systems including the Battle Damage Control System (BDCS). The Automated Power Management System (APMS) manages the generation and distribution of electric power in the ship. The ship has an ATM based Integrated Ship Data Network (AISDN) which serves as the backbone on which the external and internal communication systems, data communication between weapons and indigenous sensors and navigation data distribution are supported. The Integrated Versatile Console System (IVCS) replaces the earlier plug in systems providing multifunction display with touch screens for displaying all navigation data and status of weapons and sensors. The IVCS also supports the internal communication of the ship. The Combat management system, with fleet functionality, is a sophisticated development with considerable participation of the navy which will effectively co-ordinate the functions of the several weapons and sensors not only on board the ship but also those of other ships in company. The P17 packs all the punch of a destroyer in her design.
The layout features wide alleyways and uncluttered upper decks. A centre line passage between the two helicopter hangars provides a clear lobby between the helo deck and the inside of the ship. The flush deck rails of the helo traversing system, besides being conducive to lower RCS, gives the ship much improved operational flexibility for the helicopter. The large bridge with generously provided bridge wings is ergonomically designed. The large windows of the bridge give very good all round visibility and the diverse equipment on the bridge  are neatly packed into consoles for good aesthetics.
How has Shivalik performed in the sea trials? What are the highlights of the signature reductions realised on Shivalik?
Shivalik has undergone extensive sea trials for proving her machinery and ship handling. The sea trials have been very satisfactory and the ship handling has been seen to be very good. The ship sails rock steady even at her top speed. The hull is vibration free and the machinery reasonably quiet.

How does the design of Shivalik compare with other designs of her class? With the experience of Shivalik, what would be the direction for the design of the follow on class P-17A?
Shivalik design embodies many firsts in IN ships. The CODOG propulsion plant, the Ship Data network (AISDN), the new Total Atmosphere Control System (TACS) for the ship’s air-conditioning and ventilation, IMCS, APMS, the  distributed PGD system using EDCs, the IVCS, etc., set her quite apart from earlier designs in terms of design concepts, automation and operational advantages. The ship compares very well with contemporary world designs in terms of capabilities packed into a class of ship of her size. The design and construction of Shivalik have produced a wealth of experience on which to further improve the P17A design. P17A will be more stealthy with covered mooring deck and flush deck mounted (VLM) weapon systems. The number of antennae on the ship will be reduced by use of a multifunction radar. The design will also explore better options for roll stabilization of the platform. In order to help cut down build periods and improve productivity, it is planned to go in for modular integrated construction for P17A. The design, project management and life cycle will be supported by a more comprehensive CAD/PLM.

How have the other new design projects benefited from the design experience of Shivalik?

Continuous design engagements of the Design organization is vital for the enhancement of design skills and nurturing of design capabilities. After the design of the P-15 class, there was some lull period when no new ship projects were sanctioned. However with the commencement of P 17 in the mid nineties, there was a resurrection of the design capabilities of DGND and the somewhat dormant skill sets got rejuvenated.  P 17 is truly a watershed in the design history of the navy in terms of adopting new design concepts and new strategy for the design projects. This has set a definite course for managing and progressing the designs of P15 A destroyers, P 28 corvettes and P 71 Indigenous Aircraft carrier.
What are the challenges faced by the Navy for the new design projects? Is the Navy able to attract quality manpower for specialized tasks like warship design? To what extent, the now available IT tools, have changed the paradigm of design processes?
There are several new challenges faced by the Navy for the new design projects. To meet the genuine new aspirations of the naval staff in terms of required platform capabilities, there is considerable pressure on new indigenous equipment suppliers to meet the more stringent noise and vibration specifications given by the designers. It is a challenging task for the project managers to drive the indigenous suppliers to meet specified standards. It is a recognized fact the world over, that any warship design is an evolutionary process, particularly in an environment of developing industry such as ours. Given this fact, it is very challenging to meet the cost and time budgets for equipment development which in turn impact the ship construction programme. The task of balancing the conflicting requirements of incorporating the latest available technologies whilst freezing specification at a finite time, poses special challenges in a country like ours. This is so as we are still maturing on many technology areas and would yet like to maintain high indigenous content. Manpower for the specialist tasks of design is another challenge faced by the Navy. However even today, the Navy is the only repository of the large pool of skilled and experienced warship designers. Naval officers, going through the grill of elaborate training in the Navy with wide job profiles relevant to preparing them as designers, still continue to be the most promising feeder source for the naval design organization. With available IT tools, there has been a paradigm shift in design processes. The availability of a suite of initial design software allows a wider exploration for optimizing design. This has consequently made the process more officer-centric. The wide area network (WAN) connectivity with the shipyards has facilitated easier and faster exchange of design drawings,data and documents with the shipyard. The availability of CAD modelling software with good integration of a Product Data Manager (PDM) will provide a robust platform for optimizing design layouts and maintaining good configuration control in design. The PDM will help capture all relevant data and linked information arranged in an organized product structure. In the near future, the available IT design tools will help progressing designs in a multi-user environment through enterprise wide efforts with collaboration of platform designers, shipbuilders, equipment suppliers and system developers.

What is the Navy expecting from the Indian Industry for the future naval platforms?
The Navy, with several new ship projects on the anvil, is looking for considerable support from the Indian industry to successfully realize the naval ship projects. The industry is urged to invest efforts to develop naval equipment meeting the stringent standards, particularly for noise and vibration, as these are crucial to meeting the performance requirements  of the ship. Modularity of systems, with standard well-defined minimum interfaces with the ship will be the thrust for the future. This will help the ship design and construction to proceed on the basis of the agreed interfaces while the equipment supplier can concurrently develop equipment within the confines of the module. Such an approach will also, to a large extent, accommodate evolutionary designs of state of the art equipment to meet the rising aspirations of the naval staff. Further, given the complexity, magnitude and resource intensive nature of development of new naval systems, a navy-industry relationship founded more on partnership than mere customer-supplier relationship would be required. This will give confidence to both parties for sharing the risks of development as well share the benefits of new technology with reduced costs.
Bharat Verma, Editor Indian Defence Review and author of the book Fault Lines and Indian Armed Forces.

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