ISSN : 0971-4413
Vol. 15 No.1 February 2007
UNDERWATER TECHNOLOGIES
Induction of latest weapons and military
technologies in the Indian Ocean has
posed new challenges to our country. To
counter these threat perceptions, DRDO
has been playing a key role in providing
the state-of-the-art indigenous sensors,
weapon systems, and materials suitable
to withstand hostile ocean environment.
Design and development of naval
systems demand multidisciplinary
approach as these encompass a wide
range of technologies. This also involves
collection and analysis of vast ocean
data to study ocean behaviour and to
design and develop suitable underwater
sensors and weapons. DRDO is
continuously striving to meet the
aspirations of the Indian navy and fulfill
the self-reliance objective of the nation.
Its contribution in the field of underwater
sensors, weapons, and materials to suit
marine environment has been
significant.
In the field of underwater
weapons, DRDO has indigenised a wide
range of technologies and is going to
equip the Indian navy with the most
sophisticated torpedoes, mines and fire
control systems. This issue of
Technology Focus covers some of these
underwater and allied technologies
developed by DRDO.
TORPEDO PROPULSION BATTERIES
50 kW Magnesium-Silver Chloride Battery
DRDO has developed a 50 kW magnesium- silver chloride sea-wateractivated (SWA) battery using magnesium alloy anode sheet, and silver chloride
cathode sheet. The battery is of pile-type configuration to realise maximum energy
density. It uses a recently developed more reactive magnesium-thallium alloy,
MTA-75. MTA-75 generates 15 per cent higher cell voltage than the currently in
use AP-65 alloy. The new alloy also made it possible to discharge the battery at a
higher current.
MTA-75 will not only enhance the overall energy-density and powerdensity values of the existing SWA batteries but will also help in realising energydensity beyond 100 wh/kg mark. The battery, which is used for lightweight
torpedo propulsion, will enhance the speed and endurance of the torpedoes.
50 kW magnesium-silver chloride battery
250 kW Silver Oxide-Zinc Battery
250 kW silver oxide-zinc battery
The current density required for a high-powered battery is of the order of 200
2
mA/cm . This demands usage of a large amount of silver per ampere hour, a major
part of which remains unrealised. To achieve the high battery voltage, a large number
of cells need to be connected in series. These complexities often result into generation
of high heat during discharging of the battery. By the end of the discharge, internal
heat generated in the cells leads to the situation where the electrolyte starts boiling.
This results in spillage of electrolyte and resistance drop in battery. High temperature
generated internally affects battery's life cycle and its separators also. This requires
working out of cell design, active material characterisation, and optimal use of
separator material. DRDO has developed a 250 kW secondary battery consisting of
zinc as anode, silver oxide as cathode, and potassium hydroxide as electrolyte. It
delivers 400 V on load at a discharge current of 625 A for a short duration of 5 min.
The battery, which is used for heavyweight torpedo propulsion, will enhance the propulsion characteristics of the
weapon. This will help in increasing the speed of torpedoes due to increased power from the present 100 kW to 250 kW,
almost within the same space.
MECHANICAL SYSTEM FOR LIGHTWEIGHT TORPEDO
Flight-in-Air Materials
High reliability of operations of the flight-in-air materials (FlAMs) happens to be the design consideration for the safe
launch of torpedo from a helicopter. DRDO has developed FIAMs system comprising suspension bands, parachute pack
including 'g' sensitive release mechanism, and the necessary release wires and delay lines for lightweight torpedoes.
The system acts as a retarder to the lightweight torpedo when dropped from a helicopter, and holds on to the
torpedo during the air trajectory phase. It gets released when the torpedo touches sea water. The 'g' sensitive release
mechanism of the system works in a small band of 1.6–2.5 g shock force.
UNDERWATER TECHNOLOGIES
February 2007
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The indigenous FlAMs system has been inducted into the Indian navy after
exhaustive user evaluation trials at sea.
MECHANICAL SYSTEMS FOR HEAVYWEIGHT
TORPEDOES
DRDO has developed the following mechanical systems for heavyweight
torpedoes:
Ë
Composite structural shell development with optimised weight against high buckling
and shock loads for members having high L/D ratio (battery shell for Varunastra, and
Taksha torpedoes)
Ë
Depth-independent dynamic frontal-seal design for application with pump jet propulsion at operating depth of
600 m
Ë
Special grade LM 25, BS:1490 aluminium alloy castings with optimised stiffener designs for
600 m deep operation
Ë
High-power propulsion power transmission shafting
Ë
Reliable torpedo recovery aids like smoke marker, headlights, etc.
Ë
Precision torque transmission actuating gearbox for control actuation system
Ë
Control system actuation mechanism (CSAM) for Varunastra heavyweight torpedo
FIAMs system
GUIDANCE WIRE FOR TORPEDOES
The guidance wire acts as a medium for communication
of data between the torpedo and the firing platform (ship
or a submarine). The wire is also a medium for
communicating data for the guidance of the torpedo
towards target during its underwater run.
DRDO has developed guidance wire spools for wireguided torpedoes. The guidance wire of 26 km length has
been divided into two spools of different lengths. Each
spool has a two-core copper cable, wound with a special
criss-cross winding technique for free unreeling of the cable
during the underwater run of the torpedo. The entire
length of the cable is free from pin holes. The two spools
are interconnected by an underwater connector and can
withstand a pressure of 40 bar.
Guidance wire spools
This system has undergone sea trials and performed satisfactorily. The system can be used for all future wireguided torpedoes having copper cable as medium of communication.
INSTRUMENTATION SYSTEM FOR TORPEDOES
DRDO has designed and developed an onboard instrumentation system for torpedoes. The system comprises
32-bit indigenous Anupama RISC processor to overcome obsolescence of a number of processors. It performs prelaunch communication, monitors health of the torpedo, executes exercise run logic, acquires and stores torpedo
parameters online, and operates recovery aids for recovery of torpedo.
The system acquires torpedo propulsion parameters like battery voltage, motor current, motor speed; target
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UNDERWATER TECHNOLOGIES
February 2007
parameters like range, bearing, velocity, echo details; and torpedo
control parameters like depth, course, roll, pitch and their
derivatives. The acquired data is then stored in a non-volatile
memory for further analysis. During the dynamic run of the
torpedo, the system monitors the health of the torpedo subsystems
and terminates its run in case of an alarm or end of run duration.
This system has successfully undergone various sea trials, and
can be used in all the future torpedoes.
SENSOR INSTRUMENTATION PACKAGE FOR
TORPEDOES
DRDO has designed and developed a sensor instrumentation
package (system) for torpedoes. The system monitors the
torpedo-control parameters like roll, pitch, and course-rate during
its dynamic run in water for its post-trial performance evaluation.
This package contains two inclinometers for sensing roll and
pitch parameters and one rate gyro for sensing the course-rate of
Instrumentation system for torpedoes
torpedo and associated processing electronics. The system has
successfully undergone various sea trials in different types of torpedoes developed by DRDO. This sensor
instrumentation package can be used in all the future torpedoes.
MODEM FOR TORPEDOES
To transceive data between wire-guided torpedoes and
ship or submarine, DRDO has designed and developed a
modem to replace obsolete components with VLSI
technology. Each modem contains modulating,
demodulating, duplexer having hybrid transformers, and
other associated processing electronics. The modem is
coupled to the guidance wire spools in the torpedoes for data
communication between the torpedoes and the firing
platforms.
The modem has successfully undergone complete
testing in wire-guided torpedoes and can be used in all the
future wire-guided torpedoes having copper cable as medium
of communication.
AIRBORNE PRE-SETTER FOR ALH
DRDO has developed an airborne pre-setter for
advanced light helicopter (ALH). The pre-setter is capable of
pre-set and release of TAL torpedo (AET) of DRDO, A244S
torpedo of Italy, and depth charge Mk ll. The unit operates on
28 V dc, and is MIL STD 810E and 462C EMI/EMC certified
for airborne applications.
UNDERWATER TECHNOLOGIES
February 2007
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TF
WGT modem-A
2
Testing and practice firing can also be done using the
TAL and A244S simulators developed by DRDO.
Three systems have been delivered to the Hindustan
Aeronautics Limited for fitment on the utility
version of the naval ALH.
Airborne pre-setter for ALH
HELICOPTOR FIRE CONTROL SYSTEM
A helicopter fire control system (HFCS) has been
developed by DRDO for the naval ALH. The HFCS interfaces
to dunking SONAR and helicopter motion sensors, for
subsurface and surface target tracking. It performs contact
motion analysis (CMA) and generates fire control solutions.
The system pre-sets and releases TAL and A244S
torpedoes, and depth charge Mk II. The HFCS meets MIL STD
810E and 462C EMI/EMC for airborne applications. Three
systems have been delivered to Hindustan Aeronautics Limited.
PANDAV BOARD
Pandav board is a cluster of five DSP-21160 and
SHARC-based digital signal processors. The Board implements
signal processing demands onboard a torpedo homing system,
and processes data acquired from real world through a data acquisition card. The Board has five ADSP-21160
hammer-head processors connected in multiprocessor configuration. Two 2 MB each, flash EP ROMs have been
provided for booting the onboard processors and data storage, respectively. The Board also has one 8 MB x 16
words SD RAM for storage of test input data. SHARC #1 and #2 have RS 232 and
RS 422 interfaces, respectively. Inter-processor communication on the board is through the link ports. A passive
back plane can support multiple Pandavs. The data transfer across boards is accomplished through a custom BUS
incorporating the protocols and FIFO depths through a FPGA.
Helicopter fire control system
The hardware configuration has been optimised to implement multi-channel array processing algorithms,
detection and estimation of target echoes by implementing cross-correlation and FFT algorithms.
TWO-STAGE MOUNTING SYSTEM
A two-stage mounting system (raft mounting) is employed where there is a demand for high structure-borne
noise attenuation. The main objective of a two-stage mounting system is to reduce vibration levels from machinery to
foundation, and thereby to radiate noise levels from ship hull.
Design of raft mounting for ship-board machinery is an ongoing area of research. DRDO has developed and
installed a two-stage mounting system for ship-board HP air compressor. A significant vibration reduction (25 dB)
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UNDERWATER TECHNOLOGIES
February 2007
has been achieved, which in turn has reduced
radiated noise levels.
The critical design aspects of the system are:
optimum mass of raft (intermediate mass);
selection/design of suitable mounts for both stages
for desired vibration reduction; and minimum
height of the system for ensuring stability.
ACOUSTIC ENCLOSURE
Acoustic enclosures for ship machinery are
designed for noise reduction. Design of acoustic
enclosures for ship-board machinery is a difficult
task because of various constraints such as space,
pipes routing and marine environment.
Two-stage mounting system
A ship-board acoustic enclosure has been designed and developed by DRDO for a 500 kW diesel alternator.
Salient Features
4
4
4
4
4
4
4
4
Size: 4600 mm x 1800 mm x
2500 mm
Steel and rock wool panel
materials
Insertion loss: 10 dB (A)
Modular construction for ease of
assembly
Air circulators for heat dissipation
Temperature indication
Access for maintainability
Importance to non-acoustic
aspects such as ventilation, safety,
lighting
Acoustic enclosure
IR SUPPRESSION SYSTEM FOR NAVAL PLATFORMS
Infrared (IR) radiation is one of the vital stealth signature that needs to be minimised to conceal the naval
vessels from IR-guided missiles. The ship signature levels depend upon the uptake of plume and metal surface
temperatures, ambient conditions (background sea and sky), and ship hull and structure temperatures. To minimise
the engine exhaust, DRDO has designed and developed an Infrared Suppression System (IRSS) for diesel engines
using eductor diffuser principle with film cooling rings, where the eductor action provides suction effect by
UNDERWATER TECHNOLOGIES
February 2007
6
TF
maintaining vacuum at higher velocities. The system entraps ambient
cool air and mixes it with exhaust plume to reduce its temperature. In
addition, intermediate film cooling slots have been provided for
continuous thermal insulating of ambient cool air to minimise direct
heat transfer.
The system mainly comprises a nozzle, mixing tube, and a threering diffuser. The main aim of suppressing the IR signature is to
eliminate the high contrast radiance sources and make naval
platforms appear as an extended low IR radiance object to merge
with ambience. Design of IRSS is associated with aero-thermal
calculations, heat transfer, fluid dynamics, and structural analysis.
CFD analysis was employed to mimic the flow configuration,
estimation of secondary air entrainment, film cooling effect, system
metal surface and exhaust plume temperature ranges, etc. 1:1 fullscale experimental studies were carried out for diesel engine to
estimate performance of the system. At 100 per cent operational
conditions, 85 per cent reduction in the temperature levels of
exhaust metal surface has been achieved.
IR suppression system
COMPOSITE PROPELLER SHAFT
Composite propeller shaft
A new propeller shaft has been designed by DRDO using carbon-fibre-epoxy
composite material to replace the existing metal propeller shaft. It reduces magnetic, ELFE
and noise signatures. The shaft is designed to transmit 224 HP at 600 rpm. The thrust
produced by the propeller was also taken into consideration while designing the shaft. It has
been successfully tested, both statically and dynamically, and maximum vibration
amplitude reduction of 65 per cent has been obtained.
COMPOSITE STANCHION
Stanchions are vertical columns to support the guard rails. These are fitted on the
edges of the top deck of a ship to prevent persons falling into the sea when the ship rolls due
to sea waves. At present the stanchions are made of steel which contributes to radar
signature. To reduce this signature, new stanchions have been made with radar transparent
materials. These stanchions have met all the requirements of naval specifications. These
stanchions give an average radar signature reduction of 10 dBsm in the x band.
Composite stanchion
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UNDERWATER TECHNOLOGIES
February 2007
1.
Place of Publication
DESIDOC, Metcalfe House, Delhi-110 054
2.
Periodicity of Publication
Bimonthly
3.
Printer’s Name
Nationality
Address
Dr AL Moothy
Indian
DESIDOC, Metcalfe House, Delhi-110 054
4.
Publisher’s Name
Nationality
Address
Dr AL Moorthy
Indian
DESIDOC, Metcalfe House, Delhi-110 054
5.
Editor’s Name
Nationality
Address
Dr AL Moorthy
Indian
DESIDOC, Metcalfe House, Delhi-110 054
6.
Name and Address
of individual who owns the
newspaper and partners
or shareholders holding
more than one per cent
of the total capital
Defence Research & Development Organisation
Ministry of Defence, New Delhi-110 011
I, Dr AL Moorthy, hereby declare that the particulars given above are true to the best of my knowledge and belief.
Sd/(Dr AL Moorthy)
Signature of Publisher
Technology Focus highlights the technological developments in DRDO, and also covers the products, processes, and
technologies.
Editorial Committee
Coordinator
Dr AL Moorthy, Director, DESIDOC, Metcalfe House, Delhi
Members
Dr Narender Kumar, Director of Life Sciences, DRDO Bhavan, New Delhi
Dr Sudarshan Kumar, Director of Materials, DRDO Bhavan, New Delhi
Dr BR Gandhe, Director of Armaments, DRDO Bhavan, New Delhi
Shri CU Hari, Director of Aeronautics, DRDO Bhavan, New Delhi
Shri Ranjit Elias, SO to SA to RM, DRDO Bhavan, New Delhi
Editorial Staff
Editor-in-Chief
AL Moorthy
Assoc. Editor-in-Chief
Ashok Kumar
Editors
Shashi Tyagi
Manoj Kumar
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QSDl% 011-23813591, 23819151
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Printing
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Distribution
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