Original subtitles

♪

Chad zdenek: A giant hovercraft--

Capable of transporting 400 passengers

And their cars,

All on just a cushion of air,

Over land or sea,

Designed by a madcap british inventor

Experimenting with a hairdryer,

Then supersized by engineering genius

To become one of the 20th century's

Most unusual machines.

Can you imagine

Something this big traveling at over 70 miles an hour,

With hundreds of people on board and their cars?

Now this extraordinary vessel

Has reached the end of its life.

Salvage teams are standing by, ready to tear it apart.

This is gonna be awesome!

[crunching]

As they strip it back,

I'll get up close and hands on

To uncover the five engineering innovations

That made it a giant of its time...

And reveal how the hovercraft revolution

Finally ground to a halt,

Leaving its technology to the modern military.

Yeah!

Ha ha ha ha!

I'm chad zdenek.

I spent seven years building rocket engines for nasa.

Now I'm taking things apart,

Breaking down giants of engineering

Piece by piece

So I can discover what made them legends of their time.

♪

Portsmouth, on the southern coast of England.

The final resting place

Of what were once the world's biggest hovercraft.

♪

I helped put shuttles into space,

I've seen all kinds of incredible engineering

Throughout my career.

But this is my first chance to work on a hovercraft.

Its engineers had a vision

For a completely new mode of transport--

Part boat, part plane, part helicopter...

And all genius.

I've always wanted to know how they did it.

And that's why I'm so excited

To finally get a chance to work inside the biggest in the world.

There they are, and they're giant!

Look at the size of them!

The princess anne and the princess margaret

Are all that's left of a fleet of six huge hovercraft.

They once each ferried 400 passengers and their cars

30 miles across the english channel to France.

♪

Film narrator: Srn4--

A new transportation system for a new world.

Chad: These craft were launched in 1969

To do something incredible--

Glide from land onto the sea.

They were unlike anything ever seen,

And right away, they captured the public's imagination.

Film narrator: Bringing new standards of speed and comfort,

The craft operate day in, day out,

40-minute schedules across the english channel,

And suddenly the channel is half as wide.

♪

Chad: But in 2000, both vessels were decommissioned.

That left only a handful of passenger hovercraft

Working anywhere in the world.

And since then,

These two princesses have been slowly rotting away.

Now they face very different fates.

The anne will be preserved

And eventually displayed in a museum.

But thanks to the soaring demand for recycled metals,

The margaret's days are truly over.

Now, the princess margaret is going to be scrapped,

And her most valuable parts are going to be reused

To preserve her sister, the princess anne.

The rest is going to be melted down and recycled.

♪

So here's my plan.

Over the next five days,

I'm going to help the team tear her apart.

While they salvage what they can to sell for recycling,

I'm gonna reveal the five ingenious pieces of engineering

That made these craft

The mighty machines they once were:

The incredible rubber skirt,

800 feet long;

The giant fans that lifted over 300 tons;

The huge propellers that broke the sound barrier;

Aviation's biggest drive shaft;

And the hull design that made the margaret unsinkable.

Hey, I'm chad.

Lewis: Hello, I'm lewis.

Chad: Lewis, what are you planning on doing?

Lewis: Now that the machine is here on site,

We're going to be lowering down the front door,

And then you'll be able to get inside.

Chad: Ok.

Lewis: And then we're gonna pull back some of this skirt

So we can see what's underneath there.

We're looking to get a lot of scrap metal from the job,

A lot of salvage from the job.

We'll start soft-stripping inside the cabins as well,

Removing chairs...

Chad: Ok.

Lewis: ...Loose furnishings--

Anything basically that's not metal,

We can get it out now-- chad: Ok.

Lewis: To make it easier for the excavator

When doing the demolition.

Chad: Yeah.

First up, the giant rubber skirt.

Turn the key on a hovercraft,

And fans drive air underneath it,

Creating lift.

Early craft were open around the sides.

So the air quickly escaped, limiting its power.

To build a hovercraft capable of heavy lifting,

Engineers needed to contain that air.

Their answer was a rubber skirt.

It was a simple idea

That they hoped would do something extraordinary--

Trap air to lift a 300-ton craft 12 feet off the ground.

But getting this concept to work was a serious challenge.

So before the demolition team shred the skirt

To sell for recycling,

I want to get inside and see how the engineering actually works.

Warwick jacobs has worked with hovercraft all his life,

And he's agreed to tell me all the trade secrets.

♪

Chad: All right, warwick, you ready for this?

Warwick: No, 'cause as soon as you chop that skirt off,

It ceases to be a hovercraft.

Chad: Yeah.

Warwick: Which is the beginning of the end, isn't it?

Chad: I know it's emotional for you,

But we've got to do it.

Warwick: Yep.

[buzzing]

There you go.

Now, that's not been seen for 20 years.

Chad: There's another skirt!

This next layer of rubber is a giant inner skirt.

Together, they form a tube that channels air around the craft

And into a huge central space known as the plenum chamber.

So this is like a giant balloon, if you will, on this side...

Warwick: It is, yeah.

Chad: ...And then the air flows in that way.

Warwick: Yeah, and it builds up, changes pressure

As it pushes down through those holes.

So the same again for you, chad.

Cut the next bit, and then we're in.

[buzzing]

Chad: There we go.

There's a doormat for you.

Warwick: And you're in now, yeah.

Chad: Oh, wow!

Look at this.

Geez.

It's getting a little tight in here,

Real tight and real dirty.

It's small for me under here,

But there's a lot of space on the underside.

This whole thing looks like it's layered with the skirt

So that when it lifts up,

That's how we get 12 feet higher.

I've cut through both walls of the tube,

And right now I'm in the plenum chamber.

This is the empty space at the heart of any hovercraft.

Lift fans forced air into the skirt,

Which inflated.

Holes in its inner wall

Channeled air into the plenum chamber,

Where it was trapped by the layers of rubber.

A cushion of high-pressure air built up,

Lifting the 300-ton princess margaret off the ground

Or the water.

It was an incredible breakthrough,

But it came with an unexpected price.

The hovercraft was so fast

That the impact of the waves on the rubber

Actually tore the skirt,

And that meant a lot of expensive maintenance.

Warwick: Every night the craft would go on jacks

That would lift the whole craft up.

One craft a night.

Chad: The jacks lifted the craft clear off the ground...

Leaving the skirt hanging free

And ready for repair.

Warwick: All night long,

15 guys would be there with their spanners and saws,

Repairing the skirts

And fixing it, ready for the next day,

Because with a dodgy skirt,

Performance goes down pretty quick.

Chad: The skirt was hundreds of feet long,

And it all had to be kept in perfect condition.

So, how many feet of skirt do we have?

Warwick: It's 185 foot long each side,

Inside and outside,

So you've probably got 800 feet of skirt,

End to end there.

Chad: Maintaining the skirt cost millions of dollars every year.

But today, the salvage team is hoping to make money

By recycling it.

♪

♪

This skirt is about three-eighths-of-an-inch-thick

Neoprene rubber.

And this excavator is tearing it apart

Like it's paper.

I gotta give it a shot.

♪

All right, enough of the reciprocating saw.

Now I'm ready to do some work.

This is gonna be awesome.

♪

This excavator can really shred.

But for this job,

It's as much about precision as power.

That's because when it comes to recycling,

It's important to separate your materials.

Otherwise you get paid less for them.

So you can see,

We've actually ripped off all of the hinges along the way,

And the reason why

Is because if there's any rubber that's mixed in with the metal,

Our recycling rates are going to be a lot lower.

So it's a meticulous job,

And it's taking quite a long time,

But it's going to pay off big time for us in the end.

♪

Finally! We've made a 30-ton pile of rubber.

The plan now is to shred it and sell it

So it can be used for the springy floor covering

Parents will recognize from kids' playgrounds.

But the skirt just held the air in.

The next piece of engineering

Is what really got this thing off the ground.

I bet I could crawl in through those blades.

We've just ripped the 800-foot rubber skirt

Off the princess margaret hovercraft.

But that was only part of the system

That allowed this thing to hover.

It's day two. Time to take a look at the fans.

Just how big did they need to be

To lift this beast into the air?

There are four fans.

But getting to them is tricky.

We have to cut through the side of the hovercraft

And don't want to damage the interior

Before we've had a chance to salvage the seats.

Hovercraft have kind of a cult following around here,

And these seats could actually sell to collectors at auction.

If you could give me a cut right down this section...

Roy: No problem at all.

Chad: If we can take all this out along here,

All the way to this section.

Roy: Yeah.

Chad: What I'm worried about is the cabin.

We still gotta take those seats out inside.

So if you're able to do this

Without affecting the floor of the cabin

So we can keep working there...

Roy: It shouldn't affect the structure

Of the hovercraft at all.

Chad: Ok.

♪

Roy has a special machine for this job.

It's a set of hydraulic jaws...

With a surprisingly delicate bite.

It's amazing how accurate he can be

With such a huge machine.

Man: Good job, roy.

Chad: Yeah, it's great.

It's amazing to have this kind of a view

On a giant machine like this.

Now I can climb right into the guts

Of this huge hovercraft.

I bet I could crawl in through those blades

And get a closer look.

♪

This is not where you'd want to be

When the engines start.

I'd be sliced and diced.

Oh. Wow!

This is a big inlet.

I'm in a giant fan.

It's mounted not vertically, but horizontally.

It sucks in thousands of tons of air

Through this giant inlet

And forces it down through the skirt

And into the plenum chamber below.

This is what made the hovercraft hover.

♪

Aviation had the wright brothers;

Hovercraft had sir christopher cockerell.

He was the british inventor

Behind this inspired piece of engineering.

Cockerell noticed how water creates friction

Against the hull of a boat,

Slowing the vessel down,

And he came up with an extraordinary solution.

Christopher cockerell: You begin to ask yourself,

Well, now is there a way around this?

One day, one thought,

Well, let's see how it would work out

If one used air instead of water.

Chad: Cockerell experimented with hair dryers and tin cans...

Before designing a prototype,

Building a scale model,

And then, in 1959,

Unveiling his revolutionary craft

To a stunned public.

Cockerell's flying saucer prototype

Had just one fan.

But the princess margaret has four,

And they're enormous.

Roy is tearing one out so I can take a closer look.

It's a really simple piece of engineering--

Just wood covered in sheet metal.

So, how do four of these very basic-looking fans

Lift a vessel like the princess margaret?

♪

Each of the four fans is 12 feet wide

And could spin at over 400 miles an hour.

That was fast enough to fill the enormous skirt

In just six seconds...

And create the air cushion

That made the 300-ton princess margaret hover.

It solved the very problem

That had driven cockerell to invent the hovercraft.

The margaret didn't have to drag its bulk through the water.

Instead, it could fly over the top,

Creating almost no surface friction.

Film narrator: The srn4 rises up on its 8-foot-high skirt

And glides down the ramp, across the sand,

And begins its 40-minute hover to France.

Chad: Like the seats, these fans could be popular

With the hovercraft fanatics around here.

So they'll be put up for sale at a collectors' auction.

But if they don't sell,

They'll have to be scrapped instead.

Two days in, and we've removed

The hovercraft's huge rubber skirt

And its four giant lift fans.

On their own,

These are two really simple pieces of technology.

But they show that sometimes in engineering

The most complicated problem needs the simplest solution.

What amazes me

Is cockerell's ingenuity in combining them both.

He did what nobody thought was possible--

Keeping 300 tons of hovercraft floating on air.

And to me, that's genius.

♪

Cockerell had unveiled his invention to the world.

Now he had to prove it could be put to commercial use.

So he set himself a bold challenge--

To make the 30-mile journey

From calais in France

Across the english channel to dover,

Using his prototype srn1, the world's first hovercraft.

On July 25, 1959, cockerell set out to make history.

The crossing took two hours.

But the moment the vessel slid onto the beach in England,

A legend of transportation was born.

Film narrator: Although it was only 6:50 a.M.,

People had gathered in large numbers to welcome her.

The principle of hovercraft had been abundantly proved.

The small prototype had turned the page

To a new chapter in modern transport.

Chad: Cockerell's success inspired a new vision.

If he could supersize his design

To offer greater power and more lift,

Then he could build a giant hovercraft.

It could carry more cargo,

Have enough seats to serve the masses,

And connect britain to mainland europe

In just minutes.

♪

Ten years later, in 1969,

Cockerell launched the princess margaret.

For the next three decades,

This would be the world's biggest hovercraft.

♪

Almost everything about it was a record-breaker,

Like the four giant propellers that provided thrust.

It's day three,

And these are the next innovation

I want to explore up close.

At 21 feet in diameter,

These props still hold the record

For being the world's largest propeller blades.

And they had to be

To propel 300 tons of hovercraft across the channel

At speeds of up to 60 miles an hour.

♪

Wow!

These are huge!

That's a lot of propeller blade.

These props may be wide,

But their lifespan was short.

They were vulnerable to damage from debris

And were designed to be replaced

After just 5,000 hours of service.

That meant the princess margaret needed a new set

Every two years.

And they didn't come cheap.

These blades were last made in 1999.

A set of four propellers took over a year to make

And cost a million dollars.

Unbelievable!

The props were made of aluminum, so they were light and strong.

Today, aluminum is valuable as a recycled material,

But this propeller won't be recycled.

♪

Can you, uh...

Yeah, there you go, right there.

Instead, the demolition team will donate it

To the local hovercraft museum.

So we're taking it apart to put into storage.

Set her down.

There you go. Yeah, right there.

Man, these are heavy!

♪

Lift it up. You guys lift up... There you go.

♪

Each prop was mounted on top of a tall pylon,

A structure that allowed the propellers

To pivot left and right.

The pilot could control the angle and speed

Of each propeller separately,

And, that way, steer the hovercraft.

So are these really the biggest propellers in the world?

Warwick: They're the biggest propulsor propeller

In the world.

You have bigger blades on windmills and wind turbines,

But as a propeller for pushing you along,

They're the biggest propulsors in the world.

Chad: The propellers rotated at up to 1,000 rpm.

That may not sound like much compared to the engine of a car,

But the size of the propellers had a really dramatic effect.

I just want to get an idea

Of how fast those props were moving.

So, they're 21 feet in diameter...

Circumference of a circle, pi times d...

♪

So...

That's about 750 miles an hour.

Now, the speed of sound is about 740 miles an hour,

So that means those props

Are moving faster than the speed of sound,

Making them supersonic.

Just like the concorde created a sonic boom

When it broke the speed of sound,

So did the margaret.

And the roar from its supersonic propellers

Could be heard for miles around.

Warwick: The propeller tips would break the sound barrier

Sometimes coming into the terminals

When the pitch changes suddenly,

So you could almost hear them in France.

Chad: It didn't take long

For others to realize the potential in such power,

And the innovations pioneered by these hovercraft

Have been used all over the world.

We're traveling fast! This thing is moving!

From armed patrols in the vietnam war...

[helicopter]

[gunfire]

To rescue craft serving disaster zones...

And from tropical swamps...

To frozen tundra...

♪

Hovercraft have proved a vital tool for the u.S. Navy.

Their ability to carry huge loads at high speeds

Still makes them ideal landing craft.

I'm off the coast of san diego,

On board their landing craft air cushion,

Or lcac.

You know, this hovercraft is so big,

And you're in the vast ocean right now,

You can't see any land.

You really lose perspective of how fast you're actually going.

And we're traveling fast! This thing is moving!

And we've got like 2-3 foot swells,

And you can't even feel anything.

It feels like you're riding in a cadillac,

Just, just moving along.

Lcacs like these

Have been in service for over 30 years.

They're carried by transporter ship

To within 80 miles of the shore...

And then launched at sea.

Even when carrying 180 troops...

12 humvees...

Or 75 tons of humanitarian aid,

They're still highly maneuverable.

This thing can turn on a dime

And deploy across almost any terrain.

Now we're heading back to the beach.

♪

Oh, man.

They give the u.S. Navy access to 80% of the world's shoreline

And the lcac unit its motto:

"no beach is out of reach."

♪

It's stopping.

♪

That's spectacular.

♪

U.S. Lcacs have served across the globe,

In iraq...

Somalia...

Indonesia.

And here in the u.S.,

They took part in rescue operations

After hurricane katrina.

♪

Today, the lcacs operate in extreme situations.

But in her prime,

The princess margaret's job was to take tourists to France.

And now it's time to rip out the passenger cabins

Where they sat.

Before we start, I want to take a look around.

The margaret had two cabins,

Configured to seat 416 people.

Over their lifetimes,

The princess margaret and her sister ship, the anne,

Carried over 11 million passengers.

And appropriately enough,

Seating was more like a plane than a car ferry.

I can only imagine

What it would have been like for the passengers

To be flying across the sea in this huge hovercraft

Back in its heyday.

♪

Film narrator: Large windows provide a panoramic view

For all passengers,

And the fully ventilated cabins are light and airy.

Passengers relaxing in spacious airline-style seating,

Perhaps sipping drinks brought round by a hostess.

♪

Chad: Now all these seats have gotta go--

Some to the museum,

The rest to auction,

Where they might be bought for use in home movie theaters.

I brought my extra tool in case we need some manpower.

[laughs]

Warwick: Ok, there it is.

There we go.

That's a lot easier.

Only another 150 more benches to do.

[laughing]

Chad: Oh, man.

Some of these have been here a long time.

These are completely corroded in.

Back in 1969,

Passengers paid around $13 to sit here.

That's about $90 in today's money.

Back then,

That was about the same price as flying to France.

But the margaret had one big advantage.

You could bring your car as well.

Film narrator: Cars enter the craft

By means of the wide bow loading ramp

And are quickly positioned with a minimum of fuss

Under the guidance of car deck personnel.

Generous overhead clearance in the car deck

Allows the craft to cope with coaches,

Light commercial vehicles,

And holiday makers' heavily laden cars.

Chad: In the first six months,

The fleet of four hovercraft

Carried hundreds of thousands of passengers and their cars

Across the channel.

Business continued to boom,

Until, in 1973,

Britain and america faced the oil crisis.

Tensions in the middle east

Meant the oil supply was cut off.

Film narrator: Traffic in the cities was down by about 10%,

And garages offered a regular service

Only to essential drivers,

Not those topping up for shopping or the weekend.

Chad: The cost of a barrel promptly quadrupled.

With the margaret burning four tons of fuel every hour,

The hovercraft faced commercial disaster.

But its engineering came to the rescue.

Designers calculated

They could increase efficiency and stay profitable

By making the craft even bigger.

Warwick: They stretched them,

So they cut them in half, about where we're stood,

Added a 55-foot section,

And you could operate the same engines,

Bigger propellers on the top.

For 10% more fuel, you could carry double the payload,

So it revolutionized and gave the hovercraft a future.

Chad: A new central section was added to each vessel.

At the time, it cost $12 million,

But it nearly doubled their capacity

And ensured the future of these two hovercraft

For another 20 years.

The extended version was christened the superfour,

And it's the margaret we see today.

Film narrator: Superfour, with its payload of 90 tons,

Can carry 416 passengers and 60 vehicles

In airline-style comfort.

♪

Chad: Next, I want to uncover the hidden engineering

That made the princess margaret unsinkable.

Wow!

The princess margaret and the princess anne

Were in service for 31 years.

Together, they each crossed the channel

Over 80,000 times.

That's more than 2.5 million miles--

100 times the circumference of the earth.

Only once in all that time did disaster strike.

It was in 1985.

The margaret approaches dover harbor.

The pilot is fighting near gale-force winds

And high seas.

There are 370 passengers on board.

Suddenly the hovercraft is blown against the harbor wall.

[crash]

Reporter: The gaping hole

In the starboard side of the hovercraft

Was an indication of the force of the impact.

Chad: 50 people were injured.

Four died.

Reporter: One of the first tasks

Was to try to get underneath the skirting

To see if the missing bodies were trapped under the wreckage,

But none were found.

Chad: It was a terrible tragedy.

But the accident could have been much worse.

Reporter: They said that if this had been a ship,

She would almost certainly have sunk.

Chad: The reason the margaret didn't sink

Was its unique construction.

And the secret to that engineering

Is hidden below her car deck.

It's day four,

And this is the next innovation I want to uncover.

The skirt and lift fans make the hovercraft hover.

But because these vessels operate at sea,

They're built with a watertight hull for safety.

That means they can float,

Even without the lift fans running.

This hovercraft is built on a raft of 150 buoyancy tanks,

Which makes it 500% buoyant.

Basically, you'd have to stack four hovercrafts on top of it

In order to make it sink.

These buoyancy tanks

Are built under the floor of the cargo hold.

To reach them, I'm going to have to smash through the car deck.

These chambers haven't seen the light of day

Since it was built 50 years ago.

I'm gonna take one apart and look inside.

♪

[buzzing]

♪

Wow! Ha ha!

I'm probably the first person to be in one of these

In over 50 years.

[knocking]

These buoyancy tanks are riveted together

And then sealed off

By the rigid floor of the car deck.

It's like a giant raft made of super light aluminum

And strong enough to support 130 tons of cargo.

Every tank is watertight,

So if one is ruptured and flooded,

It won't affect any of the others.

The side effect of this design

Is a giant hovercraft that's actually ultra-buoyant.

There's 150 of these on this hovercraft.

Now I can see why it's virtually unsinkable.

So the construction on this,

You actually have the wood top deck

Which is coated with an anti-slip material.

Underneath the wood,

We've got two layers of aluminum sheeting.

But what gives it its strength

So that you can drive the cars on here

Is this honeycomb.

It's actually very, very fragile.

You can kinda see...

[banging]

It's very easy to dent into it,

But what it does

Is it keeps the spacing between these two aluminum sheets,

And with that spacing, this stuff is rock hard.

This was what kept the margaret afloat,

Even when the worst happened.

The tanks were a priceless piece of engineering.

But today, their only value is as recycling.

♪

With aluminum fetching a dollar a pound,

The demolition team wants to get back to work.

[clattering]

Before they do,

There's one part of the craft we want to save for posterity--

The cockpit.

This is the man who knows it best,

The princess margaret's last ever pilot,

John hawkins.

How's it feel to be back in here?

John hawkins: Well, it's good.

It's still surviving, isn't it?

[laughs]

It had to be a little bit tricky.

I mean, when you're flying a plane,

You don't have the lift fans that you've got here.

And you've got four different propellers

That could spin all the way around.

John: Well, the beauty of it is,

It's set up to make it very easy for yourself,

Because this yoke here--

If we were to do that,

All the pylons would go to push you

In a certain direction, that direction.

Chad: All at the same time?

John: Yeah. Doing a turn, for instance,

You could do a turn with the rudder.

You put the thing over.

Chad: Ok.

John: And the rudders would go over to take you...

To starboard there.

Chad: Yep.

John: The beauty of these things,

I've never known anyone not to enjoy driving them.

Chad: John makes it sound simple,

But flying these took considerable skill.

To maneuver the craft,

The pilot could use the rudders,

Pivot the pylons and propellers,

Or adjust the pitch of the prop blades.

He also had to balance the vessel

By varying power to each of the lift fans,

Or even pumping fuel between the fuel tanks.

All this was controlled from here in the cockpit.

It may seem complicated,

But the cockpit's design worked so well

That it was never updated.

For me, that makes this a piece of engineering history.

I'm delighted it won't be scrapped.

Instead, it will be saved and exhibited

In the local hovercraft museum.

But that means we have to take it out in one piece,

Which could be tricky.

♪

So I'm only using a pickaxe

To make a starter hole for the saw blade.

Once I get the blade in there,

I'm cutting through the sheet metal

But not the structural supports.

We've got to make sure those structural supports stay intact

'cause if we don't,

George and I are both falling through.

[buzzing]

As we cut around the cockpit,

We're leaving four of these structural support beams intact

To bear the weight.

Then we attach slings...

Let the crane take up the tension...

And cut through the last of the beams.

Now the crane takes

The full weight of the cockpit...

[engine revving]

And we can lift it out.

Perfect.

Good job, george!

♪

♪

That's how you take a cockpit off of a hovercraft.

As you can see,

We've a big hole in the roof of the hovercraft.

We lifted it up, it didn't buckle at all,

And now we've got a beautiful cockpit for the museum.

The analog dials and manual controls

In the margaret's cockpit

Are from another era.

But on this u.S. Navy craft,

Everything is state of the art.

I'm getting ready

For a once-in-a-lifetime opportunity,

To take the controls of this u.S. Navy lcac.

First, a brief from senior chief petty officer eric crafton.

He's an lcac pilot

Who's served in iraq, afghanistan, and haiti.

So what's it like to actually operate this thing?

Eric crafton: If you don't drive this craft,

It's going to drive you.

So, every slope, the wind, the waves...

Everything is a factor.

Chad: You've got the lift, you've got the propulsion,

You've got the bow thrusters.

It seems like there's a lot going on.

Eric: It is very tricky.

You're using your feet for your rudders,

Your left hand for the props,

And they're controlled independently,

And your right hand for your bow thrusters.

Chad: And if you combine that

With this thing not even touching the ground...

You know, almost like a frictionless surface,

I imagine that adds a layer of complexity to it as well.

Eric: It does.

You have to be in control to make the craft do what you want.

Chad: Gotcha.

It certainly doesn't sound easy.

But what better way to learn

Than from this elite u.S. Navy lcac crew?

It's safe to say I'm pretty excited.

Oh, man!

Man: Welcome to the forward con. Chad: Woo hoo hoo hoo hoo!

Man: All right. Let's do it.

Chad: Oh, it's not every day

You get to drive a $30 million hovercraft.

Right now, the lcac's floating on its hull.

But as soon as I give the order...

Engineer, bring us on cushion.

Engineer: All right, got ya, con. Bring on cushion.

Chad: The lift fans kick in.

The skirt inflates.

And in less than five seconds,

We're floating on a cushion of air.

Bow thrusters forward.

Woman: Bow thrusters are forward.

Chad: As the engines rev up,

The 120-ton craft begins to glide forward.

♪

Seconds later, we're pushing 20 miles an hour,

Then 30...

40...

50 miles an hour in a 120-ton craft,

Loaded with six humvees and a dozen marines.

Incredible!

Yeah!

Ha ha ha!

It feels amazing!

♪

I am flying a hovercraft.

Wow!

This is at least three times faster

Than a conventional cargo boat.

Low cushion.

Man: Low cushion? Gotcha, con.

Chad: Ha ha ha! Wow! Man: Hope you enjoyed it.

Chad: Yeah, that was awesome.

As soon as we kill the fans, the skirt deflates

And the lcac lowers onto its watertight hull.

I had four engines at 4,000 horsepower each,

And we were doing about 40 knots,

Which is probably around 50 miles an hour.

And it felt like we were just gliding on air.

It was amazing.

♪

The lcac uses the same principles as the margaret

But is only one-third its size.

The engineering has been refined

To create more power and lift

From smaller engines

And just two propellers.

But the margaret had four props

And four lift fans.

These giant moving parts were all joined together

By one final piece of engineering.

And it's buried deep inside the superstructure.

It's the innovation I want to uncover next,

Before my final goodbye to this engineering legend.

[crunching]

♪

Just like peeling an onion,

Layer by layer.

♪

Ok.

There it is.

The drive shaft.

This is just part of a huge drive shaft.

It rotated at high speed

To deliver power

From the engines at the rear of this hovercraft

To the propeller and lift fan

Via the pylon,

All the way at the front.

This drive shaft had to be 140 feet long.

It was the biggest aviation had ever seen.

And the margaret had two of them.

This is one of the gigantic 140-foot drive shafts

That connect to the forward pylons.

And together they're some of the most valuable recycling

On the hovercraft.

No one is quite sure what it's made of.

My bet is aluminum,

Which is very light and very strong.

We're not sure how to get it out, either.

Roy's just going to have to grab a section and pull.

So what do you think, roy?

You think you could get the drive shaft out?

Roy: Yeah, we'll have a go.

I'll grab it in the center there where the joint is.

Chad: Yep.

Roy: And it should snap the bolts off then.

♪

♪

Chad: Wow!

Let's see.

Oh, ho ho ho ho!

Alright, moment of truth.

I have a magnet here,

And it's definitely not steel.

I'm not sure if that's the bolts or the flange,

But this is definitely aluminum,

And this is worth a lot of money.

This is just one section of the drive shaft.

The whole thing weighs 2,500 pounds.

And remember, there's two of them.

Together, they could be worth up to $5,000 as scrap.

But to get every piece out,

The demolition team will have to tear the margaret to shreds.

There's no turning back now.

♪

The hovercraft boom years did not last.

By 1994, their future was under threat.

Conventional car ferries had become faster

And could carry more cars.

Budget airlines offered cheap flights.

And a new tunnel under the seabed

Was about to connect England and France by rail.

Meanwhile, margaret's fuel consumption

Was costing up to $7 million a year.

On top of that was the bill for routine maintenance and crew.

It all added up to an annual running cost of $18 million

For a single hovercraft.

To stay profitable,

The operators needed to sell more than just tickets.

That something was alcohol.

Just like international airports today

Make money selling duty-free alcohol,

Cigarettes, and perfumes,

So did the princess margaret and the princess anne.

Film narrator: Duty-free facilities on board a hovercraft

Do not require lengthy queueing by the passengers.

Instead, they enjoy a pleasant and efficient service

In the comfort of their seats.

The cheerful cabin staff

Can bring round drinks and duty-free goods,

Ensuring that everybody is served

During the 30-40 minute flight.

♪

Chad: Ticket prices were dropped to around a dollar.

For that, you could travel to France

And stock up on cheap alcohol.

The trip became known as a booze cruise.

Soon, the hovercraft's huge running costs

Were paid for almost entirely by profits from cheap alcohol.

It's hard to believe that a hovercraft this big

Survived from duty-free.

Warwick: Yeah, and in fact, on some of the trips,

If they were going a bit too quick,

The stewardess would call up to the captain on the bridge

And say, "slow down, we're still selling the duty-free,"

So we'd do a little nip and turn and slow it down a bit.

But, yeah, duty-free

Was the saving grace of the hovercraft.

And towards the end,

It was very much people going for a day to get duty-free

And not paying a premium.

They'd pay a pound for a day return

And come back laden with duty-free.

Chad: Then, in 1999,

The eu abolished duty-free between european states,

Including the united kingdom and France.

With no way to cover the huge cost

Of running these machines,

The writing was on the wall

For both the princess margaret and the princess anne.

Warwick: The duty-free ending

Really spelled the end for the hovercraft.

It competed for ten years against the channel tunnel.

That didn't kill it.

They survived an accident, they survived price wars,

They survived an awful lot of things.

But the death knell was the abolition of duty-free

In the year 2000.

And overnight,

The hovercraft was no longer a viable concern.

Chad: Less than a year after the abolition of duty-free,

Both the margaret and the anne were permanently retired.

[ship horn blows]

The era of giant hovercraft on the english channel was over.

The princess anne and princess margaret,

Two extraordinary pieces of engineering

Run aground by economics.

And now it's because of economics

That the princess margaret is being torn to pieces

And recycled.

The demolition team

Has already shredded the 30-ton rubber skirt.

They've ripped out and sold the four lift fans.

One of the giant props has been preserved for a museum,

Along with the seats and the cockpit.

But now it's time to really cash in

With what's left of the 300-ton princess margaret.

Melted down, it will be worth around 40 grand.

All together, that's a total of about $175,000

For five days of salvage and three decades of history.

♪

The princess margaret

Was born in a moment of inspiration...

♪

Developed for a decade...

♪

Only to be launched and made even bigger...

♪

Before making its name over millions of miles of service.

♪

Now it's being transformed,

Bite by bite,

From a legend of engineering...

Into a pile of scrap,

Ready for recycling...

♪

Perhaps even to become part of the next generation

Of mighty machines.

♪

The margaret is now gone forever.

And with it, cockerell's vision

For a hovercraft to serve the masses.

But his inspired idea for an amphibious craft

Lives on.

Not as a huge passenger vehicle,

But as a tool for the military

And emergency and rescue services.

Today, hovercraft can be found working

In some of the most extreme conditions in the world.

They all started with the princess margaret.

♪

Although we scrapped it,

Thankfully some of the parts are going to be used

To preserve this incredible craft behind me.

Being here has given me a chance to explore

Just how the giant hovercraft worked,

To uncover the wonders of its engineering

And the genius of its simplicity.

And it's genius that is at the heart

Of every incredible invention.