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Today on "Impossible engineering"...

The Virginia class,

one of the most advanced submarines ever built.

To come down the waterfront,

to see these submarines being built,

it is truly a magical thing.

Pushing marine engineering to its limits.

The Virginia class is acoustically

the stealthiest submarine that the U.S. Navy has ever produced.

It took revolutionary engineering...

What we have now on Colorado

really incorporates the latest and greatest

of what's out in industry.

To make the impossible possible.

Submarines are an invaluable asset to the U.S. military.

After decades of service,

their fleet is in need of an upgrade.

The Navy was looking to a replacement

for the 688 class ships.

They were nearing the end of their useful life.

Similar to a vehicle, it gets wear and tear over time,

and it was time to come up with the newer model.

What designers came up with

is breaking the boundaries of maritime engineering.

What we're looking at

is the 15th Virginia class submarine,

the U.S.S. Colorado.

She's 377 feet long.

She can dive to depths greater than 800 feet.

She can operate at speeds greater than 25 knots.

The Virginia class is one of the most advanced

nuclear-powered fast-attack submarines ever produced

for the U.S. Navy.

At the electric boat shipyard in Groton, Connecticut,

a 15th Virginia class vessel is under construction.

Starting with the first ship of the class,

it took 15-million hours to build that ship.

And with the Colorado,

we brought that cost down to 10-million hours.

That's the kind of effort that's required

to put one of these remarkable ships to sea.

I've served on three classes of submarines,

and by far, the Virginia class is the best-engineered

that I have had the pleasure of serving on.

These technological titans are as long as 26 cars.

Each sub weighs 7,800 tons.

That's 40 blue whales.

They're equipped with an advanced nuclear reactor

and can dive to depths of almost 800 feet

or inch across shallow water with pinpoint accuracy,

thanks to a control room

that's equipped with an automated navigation system.

The pilot can literally dial in

any depth, any speed.

It allows the ship to operate

in much shallower water close to shore.

The combination of stealth, endurance, versatility,

the range is truly a benchmark for all ships.

The engineers of the Virginia class sub

have created a modern marvel,

one that would have been impossible

had it not been for the great innovators of the past.

Humans have been diving to the depths

of our oceans for centuries.

Hmm?

Hello!

Ancient sponge divers used to plummet to the sea floor

using heavy rocks.

They held their breath for minutes on end

to retrieve precious bounty.

In the 5th century B.C.,

Greek diver Scyllis breathed underwater

using a hollow reed...

Hmm?

Allowing him to sabotage the enemy Persian fleet.

Legend has it Alexander the great

used the first submersible craft.

He dove into the Bosporus straits

using a clear glass barrel to spy on enemy sea defenses.

Controlling a vessel underwater was nearly impossible

thousands of years ago.

And today, it's still a huge challenge.

At the David Taylor model basin facility in Maryland,

nautical designers are testing their submersible designs

at the annual international submarine races.

Scores of young engineers from around the world

have brought submarines that they've designed and built

with the goal of becoming the fastest human-powered submarine.

The challenge is go 100 yards

without coming out of the water, touching the bottom,

touching the sides, or any part of the submarine falling off.

100 yards may not seem like much,

but controlling a submersible's buoyancy is no easy feat.

So up and down is a little bit difficult.

Left and right so far has been really good.

I can follow the line.

It's just been a question of keeping the buoyancy right.

Did we make it further than before?

We've got about... Yeah, sort of halfway.

The trim is slightly off.

Like, the controls seem to be working.

The propeller's definitely working.

The key to the perfect submersible continues to elude

even the finest young engineering minds.

But they're getting close,

thanks to an invention created almost 250 years ago

by David Bushnell.

Dr. Rhys Morgan is at the royal Navy submarine museum

Ginosport, England,

uncovering information about a secret weapon

from the revolutionary war.

And this is it... the Turtle...

The first submersible used in recorded underwater combat.

Bushnell's plan for the Turtle

was to sneak up on the British enemy ships

moored in New York harbor.

The vessel had lots of weights in it

to help it sink into the water,

and underneath the base, there was a ballast tank,

which would be filled with water.

And the operator, a man called Ezra Lee,

would pump the water in and out of the tank

to help sink to the right depth.

As the Turtle slips underwater,

its two surface-mounted snorkels seal.

The pilot powers the craft

using a hand-cranked front-mounted propeller.

As he approaches his target, he readies the Turtle's weapon.

The Turtle's weapon, a keg of gunpowder,

was attached to the back of the wooden hull.

As the submarine silently crept up underwater

to the base of the ships,

it would be attached by this drill,

which would be literally hand-drilled

into the base of the ship.

Unfortunately for the pilot, Ezra Lee,

the British fleet had metal hulls.

By sheer bad luck,

Ezra Lee wasn't able to drill into the ship's hull,

so the Turtle was a bit of a failure.

But having said that,

it did set the precedent for submersible combat,

and the principles of ballast tanks and propulsion

still to this day remain on all submarines.

The Turtle can only hold one person.

The U.S. Navy's Virginia class can hold 135 people.

Ships manager Patty McDaniel

is charged with fitting out the 15th Virginia class sub.

One of the challenges with the design

of the Virginia class ships

is all of the services and equipment

that we need to fit into a tight space.

So all through construction, we tried to design having spaces

to put all of the services up in.

One of the other challenges with that is the crew,

when they come out to sea,

these racks are the extent

of the space many of the crew members

have to store all of their items.

So just this thickness deep is what these sailors have

to have all of their clothing and books

and whatever they choose to take out to sea with them.

Tight quarters are a recurring theme on board,

regardless of rank.

This is the wardroom of the Virginia class submarine.

So the wardroom, as you might imagine,

is where the officers gather to eat, among other things.

It's also where a lot of the meetings happen

to discuss all of the ongoings on board the ship.

Interestingly, too,

submarines are very limited on space.

So the table is a large, clear surface.

So this doubles, out at sea,

as if you needed to have an operating table.

Not only can the Virginia class

accommodate more people than the 17th-century turtle submersible,

it can also dive much deeper.

They can reach depths of about 800 feet,

thanks to a system of internal and external ballast tanks.

We have five external ballast tanks

that are normally filled with air

when I'm riding on the surface.

When it is time for us to dive,

we'll open vents on those ballast tanks.

There's grates on the bottom of the ship

that allow water to come in, displace the air,

making the ship

just slightly negatively buoyant.

We then proceed down to the depth

that we want to go to,

and we use internal ballast tanks

to make the ship neutrally buoyant

that then we can progress on our way

whatever depth we choose.

The crew on board the Virginia class

have an abundance of cutting-edge controls

at the firingertips,

one of which is replacing the most iconic feature

in submarine history.

The $2.7-billion Virginia class submarine

is the U.S. Navy's most advanced attack sub.

The 15th vessel of the class is currently under construction

at Groton, Connecticut.

Ships manager Patty McDaniel

is in no doubt about its engineering pedigree.

What we have now on Colorado really incorporates the latest

and greatest of what's out in industry.

We're always improving, we're always getting better,

and we'll continue to evolve.

The crew on aboard the Virginia class

have an abundance of cutting-edge controls

at their fingertips,

one of which is replacing the most iconic feature

in submarine history.

The periscope has been a key component on the submarine

for over 100 years,

but engineers on the Virginia class

are taking a bold step toward the future

by replacing the periscope

with a state-of-the-art photonic mast.

The photonic system is a mast

with a sophisticated camera system

that allows what would normally be displayed just in a periscope

to displayed on wide-screen monitors throughout the ship.

I used to have to have

an optical periscope that came down,

which drove the construction of the submarine

and the orientation of all of the rooms on the submarine.

Bulky periscopes force most submarine control rooms

to be located on a cramped upper deck.

On the Virginia class,

the compact imaging equipment

is housed in a part of the submarine known as the sail.

This allows the sub's control room

to be built on the wider second deck.

My control room that I'm standing in right now

houses all of the important decision makers.

It really brings the crew together to operate as a team,

as a unit.

I really believe the Virginia class submarine

has set a benchmark for marine engineering.

The designing and building of the Virginia class

was a continuation of all the great work we've done

for over a century.

It's not just the photonic system

that makes the Virginia class revolutionary.

A virtually silent propeller, known as a propulsor,

drives the nearly 400-foot submarine

and a sophisticated system of sonar arrays

allows it to map its way

across the ocean floor.

The ability to put literally tens of thousands

of horsepower into the main engines,

into the propeller, and yet be so quiet...

The level of technology required to do that is amazing.

War shield here. 0-5-4 rate, almost 10 yards.

The Virginia class is acoustically

the stealthiest submarine that the U.S. Navy has ever produced.

The Virginia class is virtually undetectable

as it travels through the world's oceans.

But how do you construct the perfect hull...

One that's optimized for sub-surface speed

and maneuverability?

It's a task that would be impossible without help

from some of history's greatest naval engineers.

During world war ii, submarines were essentially surface ships

that could submerge themselves for up to 48 hours.

Underwater, the vessels were cumbersome and inefficient.

Improving performance meant a total redesign.

Naval engineering professor Matt Werner

has come to the Webb institute of naval technology

to see firsthand what post-world war ii engineers

came up with.

So here we have our world war ii submarine,

and if we compare it to this model of a surface ship,

we see a great number of similarities.

This hull form is really about traveling on the surface.

Its sleek design creates

an extremely low bow wave,

resulting in a small wake and low resistance.

Perfect for minimizing drag on top of the water.

When we take this same hull form and place it below the water,

we pay a penalty for this type of hull shape.

Surface-mounted equipment and an uneven hull shape

create two types of drag...

Frictional drag between hull and water

and form drag as water separates from the hull.

This leads to resistance-inducing Eddies,

which dramatically reduce speed.

Admiral Charles Momsen was determined to come up with

a more efficient design.

The U.S. naval officer

commissioned over 25 large-scaled models.

Those models ultimately resulted in the teardrop hull form

that became the standard for all modern submarines.

To appreciate this game-changing design in motion,

Matt analyzes the hydrodynamic qualities

by injecting dye into the tank.

So, we've got the model in the water now.

We're towing it below the surface.

We put dye in front of it,

and the model will pass through that dye field,

and hopefully, what we'll be able to see

is a nice, smooth flow across the stern of the moDel

as it passes by, so let's see how it goes.

It's coming into the window now and right into the dye field.

And the bow goes through the dye.

Wow, look at it!

Look how smooth the flow is off the stern

as it passes through that dye field.

That's showing me we have very low resistance.

The hull's teardrop shape

dramatically reduces both frictional and form drag.

So after countless hours, tests, and calculations,

admiral Momsen and his team had done it,

and this is three sult... The U.S.S. Albacore.

The albacore changed the face of submarine design.

By getting away from that ship-type hull form

and going to a true submerged-type hull form,

we have the fastest thing in the water,

the most maneuverable sub ever to that point,

and the baseline for all subs to come.

It's been 60 years

since the albacore first set sail,

and the U.S. Navy's latest and greatest submarine,

the Virginia class,

is using admiral Momsen's game-changing teardrop hull.

We have very strict circularity requirements

to ensure the hull sections are very circular.

And when we join them together to form the pressure hull,

it must be extremely straight so that our travel

through the water uses the minimum amount of energy.

And this manufacturing center is where it all comes together.

We have 3,600 dedicated men and women

who take raw steel plate, pipe, and cable

and create completed 2,000-ton modules.

The U.S. Navy's Virginia class

is pushing the boundaries of submarine design.

Program vice president Ken Blomstedt

has been at the heart of its engineering since 1996.

When I saw the original requirements

for the Virginia class,

there were several requirements

that I thought were pretty challenging.

But as we started to build the ship,

it really came together

and turned into just a great platform.

Each submarine is made up of four super-sized modules

that, when combined, measure almost 400 feet.

The vessel contains around one-million components

and requires 10-million man-hours to build.

We have 3,600 dedicated men and women,

who take raw steel plate, pipe, ancad ble

and create completed 2,000-ton modules.

Raw steel plate is brought in.

The cut machines automatically cut the plate

to the right dimensions.

In the case of pressure hull structure,

it's rolled to get that circular shape for the pressure hull.

It takes 5,000 tons of force to form the steel

into the iconic submarine shape.

Engineers take a sideways approach to assembly.

Hull cylinders are turned axis vertical

and outfitted with structural shapes like internal tanks

and large piping assemblies.

It allows us to use cranes and vertical picks

to drop those assemblies in

and more cost-efficiently install them.

Next, each cylinder is placed horizontally

so the decks can be slid in.

The completed modules are then shipped off for final assembly.

When you pair up the last hull section,

and you actually have the ship look like

a whole ship together in a bay,

it's really exciting to see it all come together.

Transporting this monumental structure

to its natural habitat is an impressive sight to see.

We actually have 78 of these transfer cars

moving in unison.

It's one individual flipping one switch,

and all of the cars start moving together.

And it drives the whole ship out along the tracks

on the floor right onto the pontoon,

and we float off.

It's really been amazing

seeing these systems that I did the calculations on

be built and tested

and then actually eventually go out on sea trials.

It's really a privilege

to be able to see it all come together.

For the Virginia class to be successful in its wide variety

of surveillance and reconnaissance missions,

it must be able to stay underwater

for long periods of time.

This crew of 135 sailors

have to be able to go anywhere in the world,

deploy from their home port,

and be operating in any ocean

and not be concerned about the amount of fuel consumption

that they are using.

So how do you propel a submarine to the most remote parts

of the globe without refueling?

It would be impossible

without help from the innovators of the past.

The Virginia class is the U.S. Navy's latest

and greatest submarine.

But for it to be successful on its many missions,

it must be able to stay underwater

for long periods of time without refueling,

a task that would be impossible

without help from the innovators of the past.

Early submersibles relied entirely

on human power for propulsion.

Accounts from 1620 show that Dutch engineer Cornelis Drebbel

submerged a fully crewed vessel into the river Thames

and then rowed it from Westminster to Greenwich.

And stroke. And stroke.

But historians now believe a semi-submerged tidal drift

may be a more accurate version of events.

Useless!

In 1863, the first mechanical submarine was launched.

The Plongeur ran on compressed air

and had an impressive top speed of 4 knots.

Ooh, la, la!

But the ship had to be incredibly long

to fit its 23 air tanks.

It also needed a support ship.

Ow! Watch it!

Cracking the submarine propulsion code

came down to one colossal scientific discovery.

Dr. Rhys Morgan is at a secret decommissioned location

in Austria to find out more.

This is a nuclear reactor...

The core of a nuclear power plant.

The core itself is a whopping 20 meters deep.

If up and running,

this reactor alone would produce enough electricity

for 1.8-million homes.

This is an incredible moment.

What an amazing feat of engineering.

The world's first peacetime use of nuclear power

occurred when the U.S. government switched on

the experimental breeder reactor in Idaho in 1951.

It temporarily powered the town of Arco,

paving the way for domestic nuclear power.

But captain Hyman Rickover of the United States Navy

had other ideas.

He saw the potential

for using this technology in a submarine.

Rickover was an incredible pioneer.

The problem with powering submarines is that most forms

of power for propulsion require air,

so the submarines had to resurface,

or the alternative would be battery,

but they just didn't last.

Rickover was convinced

that the fundamental process of a nuclear reaction

to boil water and create steam could be a source of power.

Nuclear reactors are just very large ways of boiling water.

And here I've got a steam cleaner

that's going to represent my nuclear reactor.

I've got some water, and when I pull the trigger,

it boils the water, turning it into steam.

As I direct the steam towards my turbine...

It starts to generate electricity,

and that turns on my light.

The difference between my little reactor here

and this enormous one here

is in the way that the water is heated.

And the answer lies at the very heart of the core itself.

Nuclear fuel rods contain thousands of uranium pellets,

and it's the uranium atoms that split,

causing a chain reaction

that generates vast amounts of energy in the form of heat.

The result is an almost limitless supply

of power that can keep on producing for years.

The problem Rickover faced was scaling down something

as huge as a nuclear reactor

down to the size of something that could fit into a submarine

and still provide the power.

What Rickover came up with

was the world's first pressurized water reactor.

The core inside his reactor vessel

heats a loop of pressurized water.

This in turn vaporizes water in a secondary loop,

creating steam to drive the main turbine,

which produces electricity.

After vigorous testing in 1954, the nautilus was launched.

This pioneering nuclear vessel traveled 1,300 miles

in less than 90 hours fully submerged.

This was a huge game changer in submarine engineering.

Previously, submarines could only stay underwater

for up to 48 hours.

Now there was absolutely no need to resurface.

Rickover and his incredible engineers

had made the impossible possible.

Captain Rickover's nautilus reactor

needs to be refueled every two years.

The designers of the Virginia class submarine

are taking this technology to an unprecedented level.

The Virginia class submarine has a life-of-ship core.

It never needs to be refueled.

Previous submarines had to be refueled during its life.

The Virginia class submarine is powered by a nuclear reactor

that has been designed to last the life of the ship

for all 33 years.

Converting seawater to steam,

this top-secret reactor plant

is capable of powering the vessel

for nearly one-million miles without refueling.

The ship has amazing capabilities.

In fact, the only limiting factor for me when I go to sea

is the amount of food that I can bring onboard.

The nuclear power provides us the ability

to operate anywhere in the world in any ocean environment.

Its unlimited power source also allows the vessel

to hover motionless in one location for weeks at a time.

The reactor on the Virginia class

is the most advanced reactor that the U.S. Navy has produced.

But sustaining a crew underwater for months at a time

is no easy feat.

We have to monitor the atmosphere controls on board

and the levels of the oxygen to make sure

that it remains habitable for the sailors.

It's a challenge

that requires even more impossible engineering.

For more than two decades,

an army of designers and engineers

have been working on the Virginia class,

one of the most sophisticated submarine fleets

ever built for the U.S. Navy.

It is wonderful to wake up every day,

to come to work.

Everyone takes a lot of pride in what we do.

And it's a joy to see it come together.

12 Virginia class subs are in service,

each equipped with a state-of-the-art nuclear reactor

that allows the vessels to remain underwater

for months at a time.

But keeping the crew safe during long-term sub-surface missions

is a huge challenge.

In the submarine, we have an enclosed environment,

and so, clearly, we have to monitor

the atmospheric controls on board

and the levels of the oxygen, the carbon dioxide,

and other trace gases to make sure

that it remains habitable for the sailors.

So how do you keep over 100 crew members

happy and healthy for months at a time underwater?

The answer lies with the work of a genius chemist

from over 200 years ago.

To appreciate the challenges

behind creating a habitable environment underwater,

Dr. Rhys Morgan is exploring a naval test facility

in Portsmouth, England.

This is a hyperbaric trials unit used by navies around the world

to test undersea and high-pressure systems.

This hut can uniquely re-create

the kind of immense pressures experienced by submarines

at the very bottoms of the ocean.

Rhys is using this technology to put himself

in the shoes of early submarine passengers to experience

how quickly the atmosphere on board can change.

This is a potentially dangerous experiment,

so I'm here with Jules, who's gonna look after me

inside the chamber.

Outside, there's a whole team of medics

looking after both of us.

This is a completely sealed unit now.

Rhys and his crew now replicate

the physically demanding work on board a submarine.

It's amazing how you do start to feel

slightly more out of breath than if you were just outside

on a normal exercise bike.

Co2 makes up just 0.04% of our normal atmosphere,

and in this quantity, it's completely harmless.

But in a sealed unit, the level builds as we exhale

and can become dangerously toxic.

We're about five minutes in now, and we've already created

half the maximum permissible co2 levels in the chamber.

So we're really starting to use up the oxygen.

Whoo! A bit hot.

Okay.

We're opening.

After nearly six minutes in the chamber,

the oxygen and co2 levels are completely unbalanced.

It's too dangerous to remain inside.

Exhausted.

I don't know how those early submariners did it.

I could really feel the oxygen content lowering

and the carbon dioxide increasing in there.

Submarine engineers in world war ii

tackled high carbon dioxide levels

using a chemical scrubbing process.

They spread large quantities of soda lime around the sub

to absorb the co2 in the atmosphere.

But by far, the bigger challenge...

How do you replenish oxygen levels

in a completely enclosed vessel?

The Virginia class submarine

is one of the most advanced fast-attack submarines

ever produced for the U.S. Navy.

Its missions require it to be underwater for months at a time.

How does the sub replenish oxygen levels

without ever going to the surface?

The answer comes from the early 1800s through the work

of English chemist William Nicholson.

Inspired by the electric battery,

Nicholson experimented with placing battery leads in water.

The result was a chemical reaction

now known as electrolysis.

This is a simple demonstration of electrolysis.

I first have my water for the electrolyzer.

Okay.

Two water-filled test tubes

are placed over the submerged negative and positive electrodes

before the electrical current is switched on.

And you can start to see immediately the gas bubbles

forming on the electrodes here.

The negative electrode is generating hydrogen.

And the positive electrode is generating oxygen.

And so each of these jars

now has displaced the water with the gas.

This reaction is caused

by the positive and negative electrodes

attracting and separating the oxygen

and hydrogen molecules in the water.

Now what we're gonna do is test the purity of the gas.

And this jar here has got oxygen in.

And if I blow this splint out,

with the pure oxygen inside, it should glow.

So there we have it. We've produced,

in just a few seconds,

enough oxygen to fill this test tube.

What we need to do in a submarine is to scale up

this whole process to provide enough oxygen

for all the submariners deep beneath the waves.

The engineers of the Virginia class

are using Nicholson's groundbreaking work

to create life-sustaining conditions underwater

for months on end.

In order to maintain that environment

without coming up for more air,

we create oxygen through electrolysis.

We have pure water.

We then use electricity to split the hydrogen from the oxygen.

We distribute the oxygen throughout the ship

and then remove the hydrogen

so that we can maintain levels right at 20%,

just like normal air.

The U.S. Navy's advanced

integrated low-pressure electrolyzer

can create over 200 cubic feet of oxygen per hour.

Potentially toxic carbon dioxide

is removed by a sophisticated amine-based removal plant.

You expel carbon dioxide, and that builds up in the ship.

I have atmosphere-control equipment onboard that absorbs

that carbon dioxide.

I then compress it

and can either store it or discharge that, as well.

The crew on board the Virginia class

will experience seemingly normal living conditions,

but they'll be up to 800 feet below the ocean,

so safety is a top priority.

Every possibility must be prepared for.

In the unlikely event of a submarine sinking,

we definitely have the capability to escape.

In case a sub's internal atmosphere is ever compromised,

Chief warrant officer Eric Nabors

trains the crew to perform a pressurized escape,

using an ingenious piece of equipme

nt trains the crew to perform a pressurized escape,

called a seie suit.

It's designed to provide the occupant fresh breathing air

through the compression and ascent phases.

It provides 75 pounds of positive buoyancy in the water.

It travels at 625 feet per minute

through the water column.

Topside, request permission to fill and equalize.

You have permission to fill and equalize.

As the regulated lifting force of the suit

propels the students safely through

the 37-foot escape trainer,

they must follow one golden rule.

The number-one rule of submarine escape is never,

ever hold your breath.

Because the escapee is breathing compressed gas at depth,

when they travel through the water column,

the pressure around them decreases.

We are concerned with pulmonary over-inflation syndrome.

This potentially fatal condition can cause the rupture

of air sacs in a crew member's lungs.

If a student were to hold their breath,

that would occur, so we teach them to breathe normally

or exhale the entire way to the surface.

Are you okay?

I'm okay.

In open water, the seie suit can withstand

up to 250 pounds of pressure per square inch.

These suits have been tested

to depths up to 600 feet of seawater.

The seie suit itself is an incredible piece of engineering.

It's been more than a century

since the first self-propelled submarines

plunged into the oceans.

Now, by drawing from the innovators of the past,

adapting their ideas, up-scaling them,

and making trail-blazing discoveries of their own,

the engineers, designers,

and workers constructing the Virginia class

are making history.

To come down the waterfront,

to see these submarines being built,

to see the crew starting to take over system by system

as we turn it over to them and bring this ship to life,

it is truly a magical thing.

The Missouri just returned from six months of operations,

and if you could imagine driving your car

for six months straight, 24 hours a day,

it's truly a testament to the engineers who designed it,

the people who built it,

and those 135 sailors who operate and maintain it

on a day-to-day basis.

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