Submarine, they are black, sleek, silent and the most lethal and secretive weapons in any country’s navy. Any opposing force on the high waves fear these killing machines. As modern standards, today’s submarines can stay underwater for months and can wipe out an entire nation with in minutes notice. But these silent hunters are the result of an extreme engineering evolution. From outside they may not changed much but, from inside they became the most efficient and sophisticated doomsday weapon.
So close the hatch, dive and check out some of the interesting facts of the evolutionary journey of these silent killers.
1. THE IDEA OF BREATHING UNDERWATER :
On 1776, at the height of American independence war the Royal Navy warships were much superior than the American warships. So the Americans found many loss in ships. They started rethinking and found a solution of rather than brute force stealth will be more effective, engineers designed a hollow wooden sphere. The idea was that a man will carry a bomb, place it under enemy ship hull and return. And most importantly the total operation will be underwater, so the sphere had two screws to maneuver underwater. A compartment at the below to flood with water which helps to submerge. Hence, the first war submarine ‘The Turtle’ a 2m long submersible was born.
But, maneuvering the vessel was totally manual, and the little space stores oxygen for 25mins only. When the Turtle reaches and tries to drill under the ship hull, the sheeting took long to get drilled. And the operator didn’t get enough time to perform his task due to lack of oxygen. After many experiments engineers found a solution. The answer lies in the very thing it travels through, water. Simple chemistry shows oxygen can be separated from water, So oxygen generators solved this problem. Now modern day subs can generate 4000litres of oxygen a day which is enough of over 100crews for months.
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2. MANEUVERABILITY :
The Turtle was difficult to maneuver so, it’s time to redesign. In 1864, a new 13m long vessel named the ‘H L Hunley‘ was invented. It is now bigger which can store more air to breath. But, the main changes are in its maneuverability. At first it was fitted with a weight that can move forward to make the nose heavy and dive or move backward to make the nose buoyant at the time of surfacing. But, it the idea was not that great as the operator moves the weight so forward the vessel nose dives and the weight can not be pulled backwards manually to counter the weight imbalance. Hunley then refitted with stabilizing fins at the front which can be operated manually and position the vessel more accurately.
The Hunley became the first submarine to course preciously and sunk a ship. In modern subs for buoyancy it uses the ballast tanks, but to maintain the pitch and angles through out the travel it uses the advance computer controlled fins also known as ‘Planes’ and tail ‘Radar’ which gives great maneuverability.
3. TORPEDO :
A submarine is nothing without its signature style torpedoes. Americans invented the ‘Spar Torpedo‘ which was basically a barrel of explosive that is attached with a spear. The Hunley need to ram into her target to stick the bomb but, it was not a efficient solution. Engineers need to go back at the drawing board and find a solution to hit targets from a distance.
At first a design came up which was a self propelling bomb, but the propulsion had a major flaw. It uses pressurized air which comes out through a small outlet, forcing the propeller shaft to rotate and releases from the rear side of the torpedo. So these torpedoes leave a trail which can be seen from the surface and can be avoided. It took another 80years to perfect a torpedo for a Submersible vessel. In world War II the German engineers made an evolutionary design.
Now the torpedoes are propelled by electric motors. So it can not be identified without sophisticated sonar system unless it hits. But solution brings new problems, the electric motor needed an enormous battery pack. Hence, the torpedo needs to be longer, like 7meters long. Now vessel like Hunley needs to return and rearm after every attack which was not practical. So it’s time to make the vessel big. The most feared and notorious predator in submarine history the ‘U-boat‘ was born. It was 77meters long and can carry up to 22 of these electric torpedoes.
So, now these vessels can destroy multiple targets in one voyage. Today’s subs have torpedoes like miniature robots. They have capabilities to target with their advance sonar system. Even some of them have optic cables connected that keeps contact after releasing from launch tubes. Which carries instruction from the weapon officer and can be steer in their path.
4. POWER :
Now, the subs have descent amount of air to breath, great maneuverability and precise weapons to attack. But a submarine needs to stay under water to maintain it surprise attack. The batteries are not sufficient for long time and it needs to recharge. To recharge and sail on the surface the vessels need to run diesel engines which also requires diesel. So the Germans designed a different U-boat not to attack but to carry fuel and refill others, known as ‘Milch Cow‘. But the vessel needs to surface and refill. At this time the vessels become very vulnerable to enemy attack and German Navy lost many vessels due to this.
So, Americans came with a new idea which changed the power concept entirely. After realizing the immense power of atom bomb, American engineers designed a nuclear reactor to generate power. Which requires a very small amount of fuel, produces no gas or smoke and can run for unlimited time period.
The reactor produces enough heat by splitting atoms, which then used for making steam. The steam rotates the turbine which runs the generator and propulsion shaft. In 1954, the first nuclear powered submarine the ‘USS Nautilus‘ was launched. She was 99meters long but still engineers managed to put a nuclear reactor inside her. She can travel 100,000kms on just 4kgs of Uranium fuel. In 1958 she completed her voyage beneath the north pole completely submerged and set world record.
Today nuclear powered submarines use far better and efficient reactors than the prototype used in the Nautilus. They have the nuclear reactors built with the most secret military hardware. They have unlimited traveling range. And produces enough power to keep every systems running and almost don’t get refueled in their entire service life.
5. NUCLEAR WEAPON :
Submarines are equipped with torpedoes. But, In the cold war Era both America and Russia became well experienced in nuclear bombs. And both were experimenting on nuclear tipped missiles, and what can be better than launching a nuclear missile from a submarine. Rather than land based missile bases submersed vessels can target from beneath the water totally undetected, and then silently moves from there.
Russians were first to test this, but the missiles are so long that it can be fit only behind the conning tower, and the vessel also needs to surface because no one ever tried to launch a missile from below the water. Americans took a step further, they redesigned the missile tubes. The tubes were sealed temporary, when the launching initiates the missile hatch opens and by applying compressed air the missile was pushed outside with great speed. Due to the momentum, the missile breaks the temporary seal and shoots out at a speed of approximately 80kms per hour from launching depth of 40-45 feet below the surface, Once in the air the rocket thrusts ignite.
These days all SSBNs(Submersible Ship Ballistic Missile Nuclear) are capable of launching 10to20 ICBMs(Inter Continental Ballistic Missile) with having 4to10 MIRVs(Multiple Independent Re-entry Vehicle) each.
Each of these missiles are nearly 40times more powerful than the bomb dropped on Hiroshima. Within minutes notice a vessel in one side can destroy a nation on the other side of the planet without compromising its position. In spite of that, modern attack submarines can launch torpedo missiles, land attack cruise missiles also.
Back from the early days, subs are used for their stalking, surprise attack and silent behaviors. They can not be seen from surface, can not be hear under the water. As light can’t penetrate after few hundred feet below surface but, sound does.
Engineers made various devices like active and passive sonar to listen under water. Hence these vessels also can be heard and can be tracked. As these listening devices get more technically advance, so do these underwater predators. Modern subs have specially materialized tiles on their body for sound insulation. All the equipment inside are mounted on rubber sheets, the reactors and turbines are designed for lower running noise.
But, a vessel needs to rotate its propeller to move, and the propeller blades creates steam bubbles from sea water due to change in pressure around the blades. It is known as Cavitation. When these bubbles pop it creates noise which can be detected. So engineers designed multiple bladed propellers which do have specific bending angles to make maximum thrust without making cavitation and makes the submarine a real silent killer.