Submarine is a watercraft which propels beneath the water as
well as on the water while a ship can travel only on water. Submarines are used
in the navy, usually built for warfare and for marine research. Submarines are
highly efficient than ships. A
submarine or ship floats due to the buoyant force which acts just opposite
gravity. However, a submarine is also able to control its buoyancy, and
therefore it is able to sink or float on surface on its own will.
The difference between a surface ship and a submarine is
that a surface ship generally tries to keep the water out in order to stay buoyant,
while a submarine has ballast tanks that are designed to be flooded when
required to sink and to have the water pushed out of it when the submarine
wishes to rise towards the surface
In 1954 the first nuclear powered submarine, USS Nautilus
was launched which was a prototype. Nautilus was
decommissioned in 1980 and designated a National Historic
Landmark in
1982. The USS Pennsylvania is also a nuclear powered submarine but the
submarine’s nuclear reactor is far more powerful. It generates more than enough
electricity to propel 17000 ton USS Pennsylvania at 45km/hour as compared to Nautilus’s
speed of 7.6 km/hour. The Electric Boat Division of Groton started building
the USS Pennsylvania in the year 1982 and completed it by the year 1984. It
sank in the year 1988 and got commissioned in the year 1989.
The USS Pennsylvania is 172 meters in length, 12.8 meters wide and
11.1 meters in height. Its weight when surfaced is approximately 16,765 tons
and 18,750 tons when submerged. The crew comprises of 17 officers, 15 Chief
Petty Officers and 122 crewmen. It has the capacity to carry food supplies for
the entire crew for 3 months.
Where does it get its power from?
The USS Pennsylvania uses a nuclear reactor that breaks uranium
which triggers a massive release of heat. This heat is used to generate steam
to rotate turbines at high speed which then drives the propellers but the
nuclear reactor is enormous in size and to accommodate it, the submarine also has
to be vast. It can travel 100,000 km for 4kg of uranium. So it doesn’t need to be
refueled at sea.
How do the crewmen breathe inside the submarine?
Each crewman requires 12 cc air every day to stay alive and more
if working hard. This way air will get over in seven days in a normal submarine.
To overcome this problem air is made in the submarine itself in the oxygen
generator from sea water by electrolysis by passing electric current into sea
water
to split hydrogen and oxygen. Four thousand liters of oxygen is
circulated through pipes throughout the vessel every hour.
How is it helpful during the war?
Submarine USS Pennsylvania contains
advanced torpedoes that are like high tech robots that can be guided on to
their target. An optic fiber spooning
out of the torpedo connects the torpedo to the submarine to obey the officer’s
command to guide it on to the target. As the torpedo closes in, it’s on board
sensors lock on and hit the target.
Torpedoes are powerful enough to sink an entire ship or a submarine.
Russians launched the first rocket atom bomb. The submarine had to
first surface the water as rocket engines needed air to burn so they don’t work
under water. But a submarine surfaced on water could be easily air bombed so the
Americans wanted to design a rocket atom bomb that could be launched without
surfacing the submarine on water. This is how they did it-
The rocket has a seal which doesn’t allow water to enter. When
rocket has to be launched, the seal breaks moment before launch but before
water could enter the hatch a valve opens from which compressed air gushes into
the hatch pushing the rocket out with 80km/hour which has enough momentum to
cut 40 meters of water. Once the rocket comes out of the water, the rocket
engine ignites and the rocket travels on its further trajectory.
How does it prevent itself from getting detected?
Light can penetrate into the sea only till a few meters but sound can travel for hundreds of kilometers so noise needs to be reduced. All the machines and the fits inside the submarine are attached with sound insulators. Most of the noise comes from the propellers. When the propellers rotate quickly, area of low pressure is created near the blades and hence the temperature increases therefore leading to the formation of steam bubbles. This process is called cavitation so the faster the submarine propels more is the cavitation and therefore noise. When these bubbles pop, they make noise. But to lower the noise propellers need to be rotated at low speed but this will also reduce the thrust which will disturb the submarine’s movement. To overcome this problem the propeller has special types of blade which even at low speeds generate enough thrust.
good work! interested in more such topics!
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