The Largest Submarine in The U.S. Navy

you can't see her she can dive to over 250 meters and stay down for six months you can't hear she can run for 20 years without refueling she is the most lethal weapon ever designed an apocalypse machine capable of devastating entire continents the USS Pennsylvania is an ohio-class submarine the biggest submarine in the US Navy now I'm right 15 degrees are understood of course three to zero captain Bradford s Neff is taking the USS Pennsylvania and its crew of a hundred and sixty five men on a patrol his submariners are a unique breed sailors on my ship have to be able to deal with being inside for an entire patrol which is not only about 72 days or so during this time the Pennsylvania will silently glide through the depths of the Pacific Ocean invisible to her enemies she is primed to unleash her awesome apocalypse in an instant [Music] Emser last man down hatch secured cross-index emerged ship tu-160 feet all beeps open [Music] five six six zero once our hatch is closed to dive a crew a sealed inside the submarine for the duration of their mission each crewman needs 12 cubic meters of air every day just to stay alive more if they're working hard even in a vessel as roomy as this the Pennsylvania's crew would run out of air after just seven days so where do they get their air from the answer the very thing they're traveling in seawater by passing electricity through the water it's possible to split the substance into its component parts hydrogen and oxygen chemist and Rashid Lowe will demonstrate how this works so we have this apparatus set up here the positive electrode here is giving off oxygen and the negative electrode here is giving off hydrogen what I'm going to show you now is that we can collect the oxygen and then reignite a glowing splint with it thus proving that that's the gas so I'm going to now turn I'll tap very carefully here we now have a tube full of oxygen we're now going to do the classic test for oxygen gas which is to see whether it relights a glowing spit there we go one two three four five a new world record six absolutely bridge so there we are oxygen from water by electrolysis electrolysis is also used on the Pennsylvania to make oxygen from seawater but on a much bigger scale here we have the oxygen generator her nickname is power number one she's Ashley Nikki because we think Nikki's better no thanks Nikki produces over 4,000 liters of oxygen every hour the oxygen is used to replenish stale air which is then circulated around the vessel pure clean air thanks to the Hilton sisters we need to breathe and if she doesn't make option for us that we can't breathe so we like to tend to her keep her happy over two centuries ago the turtles operator could stay submerged for just 25 minutes on the Pennsylvania today the supply of air is limitless when people first built submarines I didn't really know how to control them so they look to nature for inspiration and they copied the fins of a fish by putting metal fins on the side of the submarine the USS Pennsylvania also has fins called planes they are operated by two of the youngest crewmen on the ship this watch station here is one of the first ones we qualify your young operators on and some guys as young as 18 19 years old are actually driving the submarine through the water he's got control of these fare water planes right here they're very good at deaf keeping the operators instructions are transmitted electronically to the fair water planes by adjusting their angle he can move the submarine up and down in the water the Pennsylvania has a second set of planes at the rear outboard controls the stern as you can see with this gauge right here the stern planes are all the way in the back of the submarine much like the elevators of an airplane they control the ship's angle [Music] you can essentially fly the ship much like an airplane under the water [Applause] [Music] during mealtimes we generally go up or down level deck so we don't send the food the drinks and everything else sliding off the tables but if we had to we'd go up and down and every once in a while I'll exercise that and they'll play catch the plate down there in World War two Hitler's submariners need a way to attack Allied shipping from a distance one weapon already exists that fits the bill a torpedo that propels itself it's powered by a tank of compressed air on launch a valve opens [Music] and the air is released into two Pistons their motion drives a propeller which pushes the torpedo through the water [Music] but this torpedo has a fatal flaw the compressed air propelling it leaves a telltale trail of bubbles this makes it easy to see it coming so the German Navy designed a torpedo that won't advertise its position with a wake of bubbles it doesn't run on compressed air this new torpedo works off a small electric motor but it needs an enormous battery to power it to accommodate the battery the torpedo needs to be over seven meters long [Music] restore you sure look good - River Rafi [Music] the Pennsylvania's mark 48 torpedo are not limited to firing in a straight line these high-tech robots can be guided on to their target to to read in our respects cr7 tube to solution ready ship ready weapon ready shoot tube to set shoot Dooku [Music] an optic fiber spooling out of the back of the torpedo carries the weapons officer's commands this allows him to steer the torpedo towards the target [Music] drops on our hold on ships you know running normally and purging on the Bering Sea rn7 thunder cannae as the torpedo closes its onboard sensors lock on and guide it in for the kill during the Second World War the German Navy have to urgently solve the refueling problem their u-boats are trying to sever Britain's supply line of ships from North America this takes the u-boats a long way from home and from fuel what they need is a way to refuel at sea so the Germans invent a submarine that carries fuel rather than firepower they call it the milk cow to build it engineers take a standard u-boat and fit extra fuel tanks these hold 400 tonnes of fuel to deliver few the milk cameras surface and roll across a fuel line [Music] during the five hours it takes to refill neither submarine can dive to safety which leaves them vulnerable to attack for the British the milk cows were clearly our most important target if you could attack them and sink them that would then limit the endurance of all the other German submarines in the Atlantic [Music] by the end of the war the Allies sink all 10 of the German milk cows the lesson is clear refueling a submarine at sea is too dangerous Engineers must find a way to make their fuel go further the answer comes in 1945 with the dawn of the Atomic Age American scientists attempt to harness the colossal energy released by the splitting of an atom to power their new submarine they fit it with a nuclear reactor this breaks down uranium which triggers a massive release of heat this heat is used to generate steam the steam shoots through a series of turbines forcing their blades to rotate at high speed these then drive the propellers but the nuclear reactor is enormous and to accommodate it the new submarine has to be vast the technical difficulties of getting a nuclear reactor into the confines of a submarine hull were just tremendous no one had ever built a nuclear reactor of the required type before no one had ever tried to deliberately put it inside a submarine and lower it into the sea no one really knew just how much power you could get from a nuclear reactor no one had done it before American engineers rise to the challenge and in 1954 unveil the USS Nautilus the world's first nuclear-powered submarine she has no need to be refueled at sea she can travel an astonishing 100,000 kilometers on just four kilograms of uranium fuel the impact of the Nautilus the first nuclear-powered submarine was tremendous suddenly had a submarine that could operate anywhere in the world and get there by traveling dived all the way today on the USS Pennsylvania behind this watertight hatch lies one of the most highly classified pieces of US military hardware the submarines nuclear reactor this reactor is far more powerful than the prototype that powered the Nautilus it pumps out more than enough electricity to propel the 17,000 ton Pennsylvania through the water at 45 kilometers per hour it also runs the myriad of machines and equipment on board fueled by a lump of uranium the size of a fist there's no sign yet of it needing to come in for a top-up this submarine was commissioned in 1989 20 years ago has not been refueled yet the one thing that limits our ability to stay at sea is food so it's fuel for the crew rather than for the submarine that limits the range of the Pennsylvania she carries a three month supply and it's some of the best Chow in the Navy trapped underwater in a steel tube foods also an important morale booster for the crew Saturday night is pizza night [Music] barbecue freeway even during mealtimes the crew are on constant alert my requirements anyone fire from the patrol [Music] the greatest fear for submariners is fire so they run through fire drills as regularly as they eat pizza they've learnt their lesson from the Russian submarine Kursk she sinks in 2000 with the loss of all hands when she's brought up from the bottom it's clear that her crew had taken too long to control a fire and the submarine had exploded [Music] captain Neff allows his crew just six minutes to bring the simulated fire under control well within time the fire marshal sounds the all-clear their regular practicing has paid off in the 1950s scientists on both sides of the Iron Curtain raced to build a rocket-powered atom bomb and what better way of launching it than from a submarine the idea of putting these things on a submarine was quite simple that the submarines are very difficult to find and they are therefore a secure base from which to conduct a nuclear attack the Russians were the first to do it [Music] their missile is so tall the only place they can squeeze it in is behind the conning tower to launch it the submarine must first surface and hoist the missile above deck [Music] but a submarine on the surface is an easy target for an enemy bomber [Music] the Americans want to take this Soviet breakthrough a step further and come up with a submarine that can launch missiles without having to surface first [Music] the problems facing the Americanists were enormous they were designing a submarine to launch these missiles from under the water no one had ever fired a missile through the water before rocket engines need air to burn so they won't work underwater so the engineers consider using compressed air instead so the secret is a seal that prevents water flooding into the launch tube when the missile hatch opens a moment before launch the seal is blown apart before water has a chance to pour in a valve opens shooting a burst of compressed air into the bottom of the launch tube the air forces the missile out of the tube at over 80 km/h it has enough momentum to cut through almost 40 meters of water [Music] once in the air its rockets are able to ignite it's day 15 of the mission and the captain runs the crew through a well-rehearsed exercise launching a nuclear strike the USS Pennsylvania carries 24 Trident nuclear missiles and is unconstant readiness to respond to a message to launch them authenticate the message shaky the message i sir gulf oscar the command to launch a nuclear missile is encoded with a cipher to ensure that the order has come directly from the President himself I concur weapons call here for mr. fire five these missiles are so big they need more than compressed air to get them through the water the Pennsylvania uses a small rocket fired into a tank of water the water super heats and instantly turns to steam [Music] this column of steam propels the missile through the water into the air the nuclear warheads on this submarine alone are more destructive than all the bombs dropped in both world wars combined in the depths of the ocean light doesn't penetrate the water more than a few hundred meters sound waves however can travel through the water for many hundreds of kilometers those hunting the USS Pennsylvania are listening out for any noise she makes that might give away her position to be stealthy the Pennsylvania must be silent one of our primary missions is to remain at sea undetected and so our job day-to-day hour-to-hour is to remain quiet so that no one knows where we are except us everything on the submarine the decks equipment running machines and even the hand dryers are insulated with rubber shock absorbers to minimize noise caused by vibrations the other large source of noise that can radiate out into the ocean is our propeller that broadband noise can travel extreme distances in the ocean before designers can build a quiet propeller they have to understand why it makes so much noise if a propeller spins quickly it leaves a trail of bubbles behind it as the bubbles pop they make a lot of noise these bubbles are not filled with air but with steam the steam is produced by the sea water boiling it is a well-known fact that water boils at a hundred degree centigrade however few people will know that at different pressures the water will boil at different temperatures if you increase the pressure as in a pressure cooker for instance than the boiling point of the water increases hence the cooking is more efficient few people will know however that at reduced pressures water will boil at lower temperatures I have here a vacuum pump and I'm going to turn on the vacuum this flask here contains water and we have it connected to a pressure gauge and we're reading at the moment approximately 15 pounds per square inch which is one atmosphere I turn on the pump do you notice the pressure dropping immediately and as the pressure drops as we approach zero bubbles start to form and the water starts to boil so here we are at room temperature but at a significantly reduced pressure almost almost the complete vacuum the water is now boiling water boiling at 20 degrees centigrade at almost 0 pounds per square inch a remarkable phenomenon sir when a submarines propeller turns quickly an area of low pressure is created on the blades this lowering of pressure causes the water to boil without heating up and produces bubbles of steam this is called cavitation formation those bubbles is dependent on how fast we rotate our propeller so the faster we go the more risk we are for cavitation the Pennsylvania's propeller design is a closely guarded secret but the basic principles of a quiet running propeller are known [Music] cavitation only occurs when a propeller spins quickly slowing the propeller down reduces cavitation and therefore noise but slowing the propeller also reduces a submarines thrust to overcome this problem the Pennsylvania's engineers developed a unique propeller with four additional specially shaped blades these generate large amounts of thrust but at much lower speeds this way the pennsylvania produces almost no cavitation or propeller noise she is a silent predator of the deep after 75 days at sea the Pennsylvania glides quietly back to base her patrol completed 20 years after her launch she is still the biggest submarine in the Western world and she will remain so until someone builds an even bigger one 

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