EMALS (ELECTRO MAGNETIC AIRCRAFT LAUNCH SYSTEM)
EMAL is the USS Gerald R Ford Aircraft Carrier |
With the new government
keen on developing the relationship of India with the global power USA has help
forge several hundred deals. The governments have adopted the new motto ---
"Chalein Saath Saath: Forward Together We Go". The governments have
stressed on bilateral ties in trade, commerce, banking, industries and military
systems.
The US-India military forces and command believes in freedom, democracy, and government by rule of law, and to increase security trough out the globe. These interests also include maintaining security and stability, defeating violent religious extremism and terrorism, preventing the spread of weapons of mass destruction and associated materials, data, and technologies, and protecting the free flow of commerce throughout the globe prospering every country.
When the President of United States of America visited India many defence projects were cleared for co-produced. Defence Trade and Technology Initiative (DTTI) that was initiated in 2012, under which the US and India would work on co-development and co-manufacturing projects has been given renewed interest. Four "pathfinder projects" were identified during Obama's visit the four products to be co-produced are the Raven mini unmanned aerial vehicles (UAVs), "roll-on, roll-off" intelligence-gathering and reconnaissance modules for C-130J Super Hercules aircraft, mobile electric hybrid power sources, and chemical-biological warfare protection gear for soldiers.
The US-India military forces and command believes in freedom, democracy, and government by rule of law, and to increase security trough out the globe. These interests also include maintaining security and stability, defeating violent religious extremism and terrorism, preventing the spread of weapons of mass destruction and associated materials, data, and technologies, and protecting the free flow of commerce throughout the globe prospering every country.
When the President of United States of America visited India many defence projects were cleared for co-produced. Defence Trade and Technology Initiative (DTTI) that was initiated in 2012, under which the US and India would work on co-development and co-manufacturing projects has been given renewed interest. Four "pathfinder projects" were identified during Obama's visit the four products to be co-produced are the Raven mini unmanned aerial vehicles (UAVs), "roll-on, roll-off" intelligence-gathering and reconnaissance modules for C-130J Super Hercules aircraft, mobile electric hybrid power sources, and chemical-biological warfare protection gear for soldiers.
A heavy E 2D Launch by EMAL , just a 50 mts enough |
With US Navy unable to check the movement of Chinese
ships has requested Indian Navy to join the efforts and has asked to stand out
openly in the South China issue. Indian Navy has received substantially from
the US counterpart. With India raring to be a ‘blue water’ force has been very
keen on operating at least a “ three CBG (Carrier Battle Group) “ with one
serving on the western and the other on the eastern water fronts. And another
in docks for maintenance. India has had experience with the CBG’s and has
operated a two front CBG. The carriers operated by the Navy are of STOBAR (Short
Take Off But Arrested Recovery) configuration. But with a STOBAR configuration
launching heavier aircrafts could not be achieved. It is crucial to operate
reconnaissance missions but this requires the ability to launch heavier
aircrafts and this in turn requires using the CATOBAR (Catapult Assisted
Take-Off But Arrested Recovery). Under the IAC (Indigenous Aircraft Carrier)
plans the IAC-I was configured with a STOBAR launch system and the IAC-II is
being planned to be configured with the CATOBAR systems. With CATOBAR systems
being very hard to maintain the Navy has went with the latest EMALS system to
assist launching heavier aircrafts off the carriers.
The Electromagnetic Aircraft Launch System (EMALS)
is a system being developed by General Atomics for the United States Navy to be
fitted on the newest Gerald R. Ford-class aircraft carriers. This system
would effectively replace the old steam propelled catapult aircraft launch
system on the old carriers. EMALS is a highly sophisticated system that is
being fitted out on the Gerald class carriers. The system has passed all
initial tests and the first land based prototype passed testing by June 2010.
The current steam catapults being used in the CATOBAR system require about 615
kg/ 1,350 pounds of steam for each aircraft launch, and this steam in return
produced from the nuclear reactor. To propel the catapult forward huge amount
of hydraulics and steam is essential. Generation of this steam is an extremely
demanding procedure and requires high amount of purified water be piped through
the nuclear reactor. This involves very high maintenance. EMALS being a
electric driven launch system has many advantages and mainly is a system that
requires extremely less maintenance.
The EMALS is based on generation and utilization of
electric current rather than the old practice of using steam. The whole
system works on the principle of Electromagnetic induction.
The Projectile is anything a Launch system or a Bullet too |
The major
components of EMALS are –
- Linear induction motor
- Energy storage subsystem
- Power conversion subsystem
- Control Consoles
Program status
Linear induction motor
Linear Induction motor is a motor that is used to achieve
rectilinear motion rather than the traditional circular motors that is
generated using a common electric motor. A linear electric motor
typically consists of a flat magnetic core with transverse slots which are
often cut straight and with coils laid into slots, each phase gives
an alternating polarity and so that the different phases physically overlap
each other. In an induction motor the force is produced by linearly moving
magnetic field acting on conductors in the field. Any conductor be it a
loop, a coil or simply a piece of plate metal, that is placed in this field
will have eddy currents induced in it thus creating an opposing
magnetic field, in accordance with Lenz's law.
When energized, the motor accelerates the
carriage down the track and the carriage in turn takes the aircraft along and
propels it off the deck. With the charge being inducted into the motor only the
section of the coils surrounding the carriage is energized. With only the coils
being energised the reactive losses is minimised to a very great extent. With
the LIM EMALS can accelerate an aircraft of around 45000 kgs to about
240 km/h.
Energy storage subsystem
To propel the carriage at the speed required the
induction motor requires very large amount of electric power. The current
required to attain this speed required production of current which is actually
more than the power that can be obtained from the ship's own power source. The
EMALS is therefore put with a energy-storage subsystem which draws power from
the ship’s main power source and stores the procured energy kinetically on
rotors armed with four disk alternators. This energy is then stored and the
alternators running and the process repeats till the need for an aircrafts
launch is felt. When the systems are activated for the launch of an aircraft
the system releases the stored energy in a very short period of time as against
the time required for production of steam in the traditional stem propelled
catapults. Each rotor can easily store more than 100 mega joules of
energy. To reduce the time betweens launch of each aircraft it the system has
been configured to be recharged within 45 seconds of a launch which is way
faster than steam catapults.
Power conversion subsystem
With the energy produced with the help of the linear
induction motor the produced energy is stored in Energy storage subsystem.
After the energy is stored it is crucial for the same energy to be released
when a launch is required. The basic function of the power conversion subsystem
is to release the stored energy in the energy storage subsystems during launch;
this is brought about by using a cycloconverter. A cycloconverter is
used to covert a constant voltage, constant frequency AC waveform to another AC
waveform of a lower frequency by synthesizing the output waveform from
segments of the AC supply without an intermediate DC link. The cycloconverter
provides a controlled rising frequency and voltage to the LIM, energizing only
the small portion of stator coils that affect the launch carriage at any given
moment.
Control consoles
It is crucial for the EMALS to be controlled and
monitored constantly and it is also crucial to maintain a constant voltage for
the LIM and to look make sure the launch of the aircrafts will be a
uninterrupted process. This whole process is brought about by control units
which are responsible for control through closed loop structure. And this in
turn allows the operators to maintain a constant tow force that reduces the
stress on a aircrafts airframe to a large extent.
The IAC-II is in advanced stage of planning and is
rumoured to be propelled by nuclear fuel. Also the carrier is being rumoured to
be around 65000 tonnes which makes the IAC-II the heaviest Indian build ship.
The main focus of a CBG is to extend the reach of the countries forces. But
India has never been in the global race for projecting a control regime
environment. Even after the carrier is inducted it’s area of operation may only
be around the IOR or the EEZ. If the CBG is charged with the safeguarding of
EEZ then reconnaissance is going to be a important part of the CBG’s daily
routine. This requires the launch of heavier aircrafts like the E-2D Hawk eye
that is to be part of the carrier’s air wing. This means the navy has to opt
for a CATOBAR configuration. But with the EMALS being a very newly introduced
system it has to be seen if the Navy command goes with the EMALS or opts to the
more proven ‘ steam propelled’ catapults to launch these aircrafts.
Article By Karthik Kakoor
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