All language subtitles for Engineering.Evolved.S01E03.1080p.AMZN.WEB-DL.DDP5.1.H.264-BurCyg_track3_[eng]

(intense music)

- [Narrator] Since the
invention of the wheel,

humans have pushed
the boundaries and
possibilities to go

faster, higher, and
deeper than ever before.

The engineering evolution of
cars, ships, planes, trains,

submersibles and rockets has
been a monumental journey of

inspiration, innovation,
sometimes failure and success.

So how did we get
to where we are now

and where are we going next?

(intense music)

Since the Wright brothers first
took to the skies in 1903,

the evolution of flight has
gone from a few meters above the

ground to the ability to fly
faster than the speed of sound.

Shaping the world we live in.

- Cars helped develop cities

and trains helped unite nations.

Planes helped to
unite the world.

- Any time we increase
the speed of travel,

we're going to
improve as a society.

- [Narrator] From the
futuristic to the fast,

to the downright bizarre,

the world of aviation has been
one of constant evolution,

but with passenger numbers
increasing year on year,

the need for bigger and faster
planes has sparked innovation

in the aviation world.

After stalling in the 1980s,

supersonic is making a
comeback with the capability of

whisking passengers
from London to New York

in three and a half hours.

Supersonic airliners are
seen as the key for the next

generation of
commercial air travel,

but this time with a bit less
boom and a greener future.

- Electric engines
and hybrid engines,

sustainable aviation
fuels trying

to make supersonic flight quiet.

- Lighter materials and more
efficient engines so we can

reduce the impact of
aerospace on the environment.

- [Expert 1] The industry
has really just exploded.

Not even the sky's the
limit, as they say.

- [Narrator] Rolling out of
a hangar in Farnborough UK

comes a new generation of
bigger passenger planes.

- Still in its testing phase,

the Boeing 777X is the
largest twin engine jet

in the world.

- [Narrator] But when it
comes to being bigger,

it's not just the engines
that come in extra large.

- It differs from Boeing's
traditional 777 in that it has

seven meters longer
wings than the original.

- This new wingspan allows
more efficient flight

and more efficient lift.

- This plane promises a 10%
reduction in CO2 emission

and fuel burn.

- The plane is massive.

It's the largest plane
we ever conceived so far,

and for that airplane we
needed longer wings to be able

to lift that load,

but those longer wings
wouldn't necessarily fit in the

places we want those
wings to fit into.

We have to fit them in hangers
and we have to fit those

airplanes at airport
terminals that already exist.

To solve that issue.

We didn't go around
building hangers,

we just figured out a
way to bend those wings

into a smaller footprint.

- Folding wingtips have been
used on military aircraft for a

number of years, especially
on aircraft carriers.

We have limited space on the
deck of an aircraft carrier to

maneuver an aircraft.

You can't turn it around easily.

The Boeing 777X is really
the first time we put

this on a commercial passenger
aircraft because we now need

these foldable wingtips to
continue that progress forward

in terms of fuel economy.

(ambient music)

- [Narrator] To make
these wings perform,

the materials used need to
be both light and strong.

At the same time,

a process is needed to fuse
different materials together to

create a superior substance.

- With conventional materials,

we're really limited
in how long we can make

an airplane's wings.

As the wings get
longer and longer,

they have to flex more
and more and more.

And metals don't deal with
that very well and that's the

advantage of composite
materials is we can make

very, very strong,

very lightweight materials
that are also very compliant

and very flexible.

- So a composite material is
where you take more than one

material and put them together
to make something that has

properties that are different
than either of the two

materials on their own.

A good example of that would
be carbon fiber composites.

Carbon fiber in and of itself,

you can use that to
make rope for example,

but you can't use fiber
to make a bulk material,

so you have to embed
it in something

that we call the matrix.

And that matrix is then the
material that holds it all

together, gives its its shape,

but it's the carbon fiber
that's embedded in that plastic

matrix that actually
provides the properties

that we're really after.

- Composite materials unlocked
the ability to increase the

size of the airplane while at
the same time decreasing its

overall weight.

We were able to
produce materials that
are as strong and as

tough as the materials
we were using before,

but have a lower density and
if you have something that has

a lower density, it's lighter.

- And that's really important
from a fuel consumption

point of view.

Not only does that benefit the
traveler and reduce costs for

the flight because we don't
need to burn as much fuel,

but also for the environment.

In lower CO2 emissions.

- We have to look
back to the late 1930s

to examine the first
use case for composites

in aircraft design
and production.

And this was the
invention and production

of the Spruce Goose.

- [Narrator] Designed to
be a troop transporter

during the second World War.

At that time,

it had the largest wingspan
of any other aircraft

at 97.5 meters,

but it was the way in which
it was built that would change

the way aircraft were
designed for decades to come.

- The Spruce Goose actually

used a combination
of lightweight

woods mixed with a phenolic
resin and then baked at about

280 degrees Fahrenheit.

- [Narrator] Phenolic resin
is a strong and durable

plastic like material
with an ability

to resist heat and chemicals.

- The Birch ply derm mold
ended up being 80% stronger

than aluminum.

Fiberglass materials were
more commonly used initially,

but they only provided
so much uniform strength.

The shift to a composite
material actually
allowed for a bit

more customization in
strength to weight.

- [Narrator] Six times larger
than any aircraft of its time.

However, the Spruce
Goose flew just one time

on November 2nd, 1947 in
Long Beach, California.

With delays in construction
and the second World War over.

There was no appetite for
this type of aircraft.

However, the potential
for innovation

that composite materials
brought was immense

and engineers were
quick to realize it.

We shifted from fiberglass
to carbon fiber.

Reinforced matrix systems as
state-of-the-art aircraft were

manufactured across the globe
to perform important missions.

An amazing example
of a specialized
aircraft is the small

but mighty Viking 400
series Twin Otter.

Less than 16 meters long
with a 19.81 meter wingspan.

This heroic flying machine
can go where most planes can't

performing rescue and resupply
emissions in the most remote

corners of the earth.

Composite materials including
carbon fibers and aluminum

alloys provide a solid structure

for the intrepid Twin Otter.

Two wing mounted turboprop
engines power this plane in and

out of the most
extreme environments.

(plane roaring)

But before any
mission can begin,

each plane must be
ready for takeoff.

(inquisitive music)

- A key pillar of safety
in aviation actually starts

on the ground.

The steps we take to properly
maintain and service airplanes

to make sure that they're
flying properly is a very

important part to making sure
that nothing happens while

we're in the air.

- We have to figure out
how long the materials

on the airplane will last
and function in a safe way

and when we have
to replace them,

we have to balance
replacement costs with safety,

we figured out that through
testing and modeling,

we were able to literally
figure out how many times we can

bend the wing and how many
times we can pressurize the

fuselage before little
tiny cracks start to form.

So then we figured out the
frequency at which these

components need to be replaced.

- [Narrator] To make
sure an aircraft is safe

to take to the air.

Engineers now have an amazing
new system that makes safety

checks even more
efficient and quicker.

AR, augmented reality.

- Aircraft maintenance takes
very specialized training

and we have tools that
assist that training.

For example, AR is a tool
that's becoming more and more

popular that allows a technician
to look at a component

through a lens or through
a piece of equipment,

help diagnose that component,

maybe break that component onto
various sections and better

understand that component and
make decisions on maintenance

that they might have
not otherwise been able

to make in the past.

- In China,

augmented reality is used for
inspecting different parts of

the planes, the
maintenance team,

they use the glasses instead
of bringing the manuals with

themselves and so on to see
the objects and compare them

with the situation that they
should be so they can provide

their comments faster
and with more confidence.

(inquisitive music)

- [Narrator] The first
iteration of AR glasses

was created in 1968 by computer
scientist Ivan Sutherland

dubbed the Sword of Damocles.

This device used two CRT cathode
ray tube monitors capable

of displaying digital wire
frame graphics that users could

see when turning their heads.

- This was a very unwieldy large
transformer like construct.

The technology was
impractically large,

but it is sort of the precursor
to what we have now for VR

and AR technology.

- [Narrator] While
the Sword of Damocles

was never commercialized,

it paved the way for the
cutting edge technology of today

that keeps planes in the air.

(light ambient music)
(plane engines roaring)

Despite all these
technological advancements,

the environmental impact of
aircraft is still very high as

they're still heavily
reliant on fossil fuels.

- The aviation industry
is responsible for about

two to 3% of the
carbon emissions

from transportation
systems around the world.

Airplanes also use kerosene
as the most common fuel for

their systems, which is not
a very clean burning fuel.

- Kerosene is a hydrocarbon,
it's a fossil fuel,

and so we should definitely
be looking for ways to reduce

our dependence on that for
air travel and hopefully the

current research into things
like biofuels or batteries or

hydrogen may alleviate
some of that dependence.

- [Narrator] In an effort to
reduce their carbon footprint.

Aviation heavyweights are
examining greener ways to power

their planes.

Industry giant Boeing has been
a pioneer in the quest for

sustainable fuels.

In 2018,

the world's first commercial
airplane flight was powered by

100% sustainable biofuels,

a result of Boeing's
eco demonstrator
flight test program.

Boeing's tests and research
revealed that aviation fuels can

be made from renewable energy
sources, including plants,

agricultural and forestry waste,

and even non-recyclable
household waste.

But these sources are
still decades away

from widespread use.

Another greener alternative
for the future of air travel is

electric airplanes.

NASA's X-57 Maxwell is a small
experimental aircraft powered

entirely by electricity, in
the hopes of making air travel

cleaner, quieter and
more sustainable,
using a high powered

distributed electric
propulsion system.

A 460 volt battery powers
its 14 motors and propellers

designed to show off
cutting edge technologies.

Of all the green
fuels to choose from.

Hydrogen is still lauded as
the most feasible option.

Although once mentioned,

there still remains public
hesitation over the safety of

hydrogen sparked in part by the
Hindenburg disaster of 1937,

an airship powered
by hydrogen gas.

- During a docking attempt,

the Hindenburg actually
caught fire and then exploded

causing the death of 35 people.

And this became emblematic
to people when thinking about

hydrogen as a fuel source.

- So using hydrogen as
a fuel is automatic.

If you have hydrogen as a
source, water is your product.

I love this fuel,

but it just won't be contained.

Containing hydrogen.

Storing hydrogen is our
biggest research challenge,

once we solve that,

water is your fuel.

Imagine that.

- Hydrogen is the
lightest atomic element.

It's very, very small molecule.

So if actually take a steel
tank and put compressed hydrogen

in it, the steel atoms
are so far apart compared

to the size of the hydrogen
atoms that the hydrogen atoms

will actually leak
through the steel.

So it's very hard to keep a
high concentration of hydrogen

in one area.

- Hydrogen can penetrate through

a lot of different materials

because the molecules
are so small,

so you have to use specific
materials to contain it than

using hydrogen as a
storage fuel inside.

For example, an airplane,

the storage would be
at much higher density

in a composite cylinder.

So it's a very different
scenario than what happened

in the Hindenburg.

You can produce hydrogen
through electrolysis of water.

You take water,

you separate the hydrogen and
the oxygen using electricity,

and then when you combine
them back together again that

produces your fuel source and
you get back with water again.

If your electricity is produced
in a carbon neutral way,

then that's a fuel source
which is intrinsically

carbon neutral.

- What a hydrogen fuel cell
is, it's a battery essentially.

So there is a positive side
and a negative side and what

happens is you pump hydrogen
into it and then we also

introduce oxygen and it's
that combination process that

produce our electric charge.

And then the byproduct is water.

- [Narrator] Hydrogen
packs a lot more energy

per unit of mass

three times more
than conventional jet
fuel and more than

100 times than that of
a lithium-ion battery.

- We know how to use it,

we know it's the coolest fuel
ever and we have so much of it

that we don't ever
have to cry about fuel.

If we can turn water
to hydrogen fuel,

I mean that's the holy
grail sort of situation.

- So if we decided to
use hydrogen as a fuel,

we'd have to consider the fact
that in its liquid form it

needs to be cooled to
cryogenic temperature.

So this is over a hundred
degrees below freezing.

- For a hydrogen economy,

one of the things that we
need to consider is fueling

stations for hydrogen.

Can we replace the
entire infrastructure
of our fuel system?

For example, with safe, reliable
hydrogen fueling system?

- [Narrator] One such
plane in development

is the Airbus ZeroE,

A project which is attempting
to design an aircraft that

uses liquid hydrogen
as the fuel.

- Liquid hydrogen poses
a number of issues

is that it's really cold,

so we have to have different
conveyance systems to get the

fuel to the engines.

We need double walled pipes
that are flexible and can move

through the wings.

We need special fuel
storage systems to store

the cryogenic hydrogen.

- [Narrator] Although one
of the major engineering

challenges faced as
liquid hydrogen needs

to be kept at a
cold temperature is

where do you put it?

- We have to protect
that fuel in some way.

We can't have it exposed
to the drag heating that's

happening on the wings.

We have to figure out how to
constantly cool that away from

the sun's rays.

So future airplanes might
look different if we decide to

change the fuel source.

- In order to store fuel
and design aircraft,

you're gonna start thinking
about putting people sitting in

wings rather than fuselages.

- If you look at
the new KLM plane,

they call it the Flying V
after the guitar I suppose,

and that's a new KLM design
that's gonna be on the air and

it has two central engines
and people are sitting

on the wings.

They've radically changed
designs of fuselages

in the planes because
they're now making

use of these alternate
technologies,

alternate ways of visualizing
so that everything is towards

low climate change, low impact.

- [Narrator] But
surprisingly using hydrogen

in flight can be
traced back centuries.

(exciting music)

- The first real man flights
are in hot air balloons

and hydrogen balloons.

As we heat air, it's
density decreases.

So if we put hot air into a
confined space like a balloon,

it'll actually have a lower
density than the air around it

and because it's lower density,

it wants to rise up and this
is what gives rise to hot air

balloons in their ability
to lift off the ground.

- In the 1780s, two brothers

called the Montgolfier Brothers.

This idea came to one of them
after watching a piece of

taffeta blow over a candle.

They'd done several experiments
where they actually built a

full size type of
hot air balloons.

They'd sent up a a bunch of
animals or some sheep and

rabbits and things like that
in their balloons before they

actually put people in it.

But in 1783 they flew this
very ornate balloon called the

and you know, before
the citizens of Paris.

And then that caused quite
the stir because I mean nobody

had ever seen anything
like this before.

Hot air balloons are really
lovely and quiet and peaceful

and all of that, but they
are not controllable.

So as a means of transportation
they become quite unreliable

because any change in the wind

could blow you way off course.

And that challenge has
never really been rectified.

(exciting music)

- [Narrator] Since the
end of the 19th century.

The idea of powering aircraft
using hydrogen has come in and

out of favor with
engineers and designers,

but some of the largest and
most extraordinary hydrogen fuel

projects were carried out
in top secret by an American

aerospace company
during the Cold War.

- Lockheed Martin was
interested in revolutionizing

what fuel sources could
be used in aircraft

and they landed on
the use of hydrogen.

- [Narrator] Project Suntan
was a dart like flying machine

that was intended
to fly at Mach 2.5,

two and a half times
the speed of sound

with a range of 4,800
kilometers and be powered

by liquid hydrogen.

- The US military had
a decision to make

on how to store this material.

We can store it as a compressed
gas or we can store it

as a liquid,

but the problem is there isn't
a lot of energy density in

that compressed hydrogen.

We need huge tanks to power
a jet or a piston engine.

Conversely, liquified
hydrogen is a great material,

it's very dense,

it stores a lot of energy and
we can put it in a relatively

small area.

The problem is in order to
store hydrogen as a liquid,

we gotta cool this to
near absolute zero.

And the problem with that is
all our piping and fuel systems

have to be able to deal
with these huge changes in

temperature from a hundred
degrees Celsius in the sun to

minus 273 degrees Celsius
with the liquid hydrogen.

There's a lot of technological
hurdles that Project Suntan

has to overcome.

- [Expert 2] Around 1957,

they actually managed to
design a successful engine that

could run on hydrogen fuel,

but the other challenge was
actually refining and storing

the hydrogen.

This proved to be too big of a
problem when compared against

the ease of actually
using kerosene.

- The issue of using hydrogen
as a fuel never really sorted

itself out and so the
project was canceled within

a few years of its development.

(exciting instrumental music)

- [Narrator] As the US Air
Force scrapped Project Suntan

and the use of hydrogen fuel

an existing spy flame
reclaimed center stage.

The incredible Lockheed U2.

- The Lockheed U2 also
nicknamed the Dragon lady,

was a reconnaissance aircraft
flown by the United States

Air Force and previously
flown by the CIA.

- This amazing aircraft is one
of the longest serving in the

world making its debut in 1956
with a range of over 11,000

kilometers and an impressive
32 meter wingspan.

The U2 was most famously used
in reconnaissance missions

to gather top secret
intelligence info
over the Soviet Union

and its allies.

- It was the U2 plane that
discovered the missiles in Cuba

that sparked off the Cuban
Missile Crisis in the '60s.

And because it was so impressive
and functioned so well that

even at times when it was
considered for retirement,

its retirement was always
pushed back and pushed back and

pushed back and now will
be in service indefinitely.

- [Narrator] The U2 has
undergone continuous
development and

modernization throughout
its operational history.

Upgrades have been made to
its engines, avionic systems,

communications
equipment and sensors,

keeping it relevant and
effective in the evolving

intelligence
gathering landscape.

To keep the Dragon
Lady in the air,

this plane must undergo major
maintenance every 1000 hours a

flight where the entire
plane is stripped down to its

skeleton and completely rebuilt.

Highly skilled maintenance
crews race against the clock to

get this behemoth
back in service.

Incredible new advances in
technology are helping aircraft

maintainers keep their planes
in peak physical condition and

perform key fixes before any
potential damage is done.

- Another important
pillar of aviation safety

is predictive maintenance.

This is a technique where
you can have a wide range of

sensors actively monitoring
different critical components in

an airplane while
they're in operation.

- We can put sensors in
locations that detect vibrations

that detect the operation
of that aircraft and send us

notifications that suggest
that some piece of equipment is

not acting like it was just
moments earlier and allow us to

check into that
before any sort of

catastrophic events occur.

Not only can this technology
be lifesaving in that it can

predict a failure
prior to it occurring,

it can lower the overall cost
of travel because now we're

not replacing parts
that would otherwise

not need to be replaced.

We're replacing them exactly
when needed and we're not

throwing away good parts simply
'cause we don't quite know

how they're functioning in
that airplane at that time.

(light ambient music)

- [Narrator] This same
avant-garde technology

is also being used to improve
the passenger experience.

- Things like more
automated luggage check-in

climate controls when
you're in the cabin,

as well as the ability to track
your flight in progress or

from your phone,

track the status of your flight
so that you can be made more

aware of delays
or cancellations.

(light ambient music continues)

Although flying in
a plane seems scary,

statistically speaking,

people have always said it's
much safer than traveling

in a car.

Flying fatalities per
billion kilometers

equate to about 0.003%.

When you jump to trains,

that figure is 0.27% and then
when you talk about cars,

the number actually
jumps to about 2.57%.

Statistically speaking,

air travel is a much
safer form of travel.

(light ambient music continues)

- [Narrator] But unfortunately
things do go wrong

and while accidents
in commercial aviation
are very rare,

even jet fueled
planes aren't immune.

- Although the instances of
emergencies in the air are far

less than they are in a car,

the potential damage is
far more catastrophic.

If something happens in the air,

there's not a lot you
can do to correct it.

You can't really pull over
onto the side of the road and

call for roadside assistance.

If something happens from high
up enough and enough of the

safety systems are compromised,

there's nothing you can really
do to prevent a plane from

having some kind of catastrophic
failure for a much larger

number of people in the plane
then would fit in the car.

- [Narrator] In recent years,

the average number of domestic
and international flights

worldwide yearly sits
at about 40 million.

The number of people who fly
annually is over 4 billion.

With such a massive
amount of aircraft

and people in the skies,

engineers have to develop
innovative systems

to ensure their safety.

- Modern aircraft collision
avoidance systems were developed

so that aircraft can't end
up in the same airspace

at the same time.

- [Narrator] Transponder
signals from each aircraft

including information such as
headings, speed and altitude,

are compared to the
corresponding data

from other nearby planes.

This process ensures that
aircraft don't enter the same

airspace at the same time.

- And basically these
systems prevent aircraft

from colliding by
giving pilots a warning

that aircraft are in a position

where they might not be able
to visually see them so that

they can make
appropriate decisions
to avoid that aircraft.

- [Narrator] Since
its implementation,

the traffic collision avoidance
system, TCAS has proven

its effectiveness in preventing
mid-air catastrophes.

In 2022, an Airbus A319 and a
Boeing 737 would've collided

with devastating consequences
while approaching

Guayaquil International
Airport in Ecuador.

- This is a very safety
conscious industry,
exactly for the

reason that they need people
to feel safe aboard an aircraft

in order for the
industry to continue.

So they really do try to
make it as safe as possible.

- [Narrator] For early
avionics pioneers,

safety wasn't a primary
concern, just getting off

the ground would do.

In the 19th century,

engineers started working
on what was a brand new

technology at the time,

propulsion systems for
fixed wing aircraft,

before fixed wing flight
could become viable.

The forces of lift and
drag had to be defined.

First person to crack this
was a British inventor

and scientist.

- Sir George Keeley is the
first person to recognize that

there are three separate things
that are required in order

to actually make an airplane
fly, and that is lift,

propulsion and control.

- [Narrator] He published
on aerial navigation.

A radical series of papers
credited with introducing the

world to the study
of aerodynamics.

- It wasn't until we'd started
understanding fluid mechanics

and aerodynamics that we
actually understood we could

achieve flight in
a different way,

and that was with
the wing shape.

- The wings of a plane are
shaped such that when air passes

across that wing, it breaks
up into two different zones.

The zone above the wing ends
up being a lower pressure zone,

and when you have
a low pressure,

you have a vacuum, that is
sucking on the wing and lifting

the plane up into the sky.

- There were no engines that
were light enough to actually

lift anything off the ground
with the materials that were

available to these
folks at the time.

Nonetheless, you start to
see a lot of people build

what we would call an airplane,

really different structures
and wing shapes and things that

would look somewhat unfamiliar,
but the ideas were there,

even the concept of, you know,

propellers and thin wings
or large wings and even

traditional cockpits.

But that engine piece hadn't
really been figured out yet,

nor had the control piece
been figured out yet.

- [Narrator] The
understanding of aerodynamics

would set the path for
advanced propulsion systems

that would help achieve heavier

than air flight over
the next century.

(inquisitive music)

The most cutting edge propulsion
systems of today are on a

whole new level in the
quest for supersonic flight,

some of the most impressive
aircraft engines of today are

the F-119 and the F-35
supersonic engines installed on

the F-22 and F-35 Panther.

But engine designers are
doing much more than simply

modifying commercial
aircraft engines.

In November of 2022,

NASA's X59 supersonic plane

had a brand new
engine installed.

The General Electric
F-414 GE100.

This four meter long beast is
like a fighter jet engine on

steroids capable of producing
22,000 pounds of thrust.

The X59 will need every morsel
of power it can get while

climbing to a cruising altitude
of nearly 17,000 meters.

But though this tough engine
is incredibly impressive,

it's not exactly
the most efficient.

- So one of the main
challenges of supersonic flight

is in the engine.

(inquisitive music continues)

The internal components of
the engine are not meant to

really deal with airflow
at supersonic speeds.

So you have to actually slow
the air down before it goes

into the engine and then after
that you need to speed it up

again to then be spit out
and create the kind of thrust

necessary for the aircraft to
achieve the supersonic speeds.

And that level of power that's
required to speed the air

back up actually results in
supersonic transport engines

requiring about
twice as much fuel

as your standard
subsonic aircraft.

- [Narrator] NASA's goal
with this new engine

is to eliminate the worst
part of supersonic travel.

The noise.

(planes roaring)

- Anytime a plane
crosses a sound barrier,

it makes a really obnoxious
loud crack that is called a

sonic boom.
(plane booming)

- Because supersonic planes
produce these supersonic booms,

we limited their overall ability
to fly over populated areas

and we confine them to flying
over a top of the ocean where

those sonic booms won't affect
as much of the population.

- [Narrator] The
excessive noise coming

from these mega engines
is one of the reasons

why commercial supersonic
flight fizzled out

over 20 years ago.

For many decades,

the king of the skies
has been the jet engine

co-invented by Dr.
Hans Van Johann

and Sir Frank
Whittle in the 1930s.

- When it comes to jet engine,

it's a whole different ballgame.

We are bringing air in with
like massive Rolls Royce fans

Then you have a timed
ignition fuel injection there,

which is coming in
a tube spraying fuel
in like super minute

particles into this compressed
hot air that is being sucked

in by the speed of the
plane through this engine.

And that entire thing blows up
giving you the thrust to push

the plane forward and this
thrust makes the air on the wing

go faster and lifts the plane.

It was a huge invention
that changed us completely.

- We owe the advent of jet
engines to military product.

That's where we find the
first jet engine applications

essentially on fighter jets.

- Through Second World War.

In six years you see a
really, really massive leap

in technology, afterwards
this has now become

a practical technology
and you can fly

commercial air travel as well.

- A lot of changes had to
happen to planes to be able to

accommodate jet engines.

Not only were they much bigger,

but they were also
much more powerful.

That amount of power
on a previously
designed aircraft could

have ripped a wing off.

The entire airframe needed to
be redesigned to be able to

accommodate this
amount of thrust.

- As we start going
faster and faster,

what we found was that wings
become less efficient if

they're designed like the
Wright Brothers designed them.

Basically,

if you have a fixed square
wing that's meeting the air

coming towards it,

you start having limitations
in terms of drag,

you really get to the point
where you can't go faster,

you you're actually
creating more drag

by trying to go faster.

- The atmosphere has
air molecules in it,

and as we move through
the atmosphere,

we literally have to part the
molecules to get through them.

We can't go directly
through a molecule,

we have to literally push
that out the way and as we

increase the speed
of our airplane,

we increase the number
of collisions with
air molecules and

so we increase the drag force
that's applied to the airplane

by all those molecules
getting out of the way.

So when we think
of going faster,

we now have to redesign
the shape of that plane.

- Everything you design to
operate at supersonic speeds is

really about cutting through
that wave drag and minimizing

its impact.

So when you look at supersonic
aircraft and you see most of

them have like a
long pointy nose,

thin swept wings usually
in a delta shape,

and then contoured
fuselage as well.

Some aircraft are even wasted
in order to direct that

airflow across the
body of the airplane.

- So wing designs have really
changed over history because

we've needed to go faster and
faster and faster and those

designs have primarily
changed to address drag.

- [Narrator] Commercial
jet aircraft revolutionized

world travel, opening up
every corner of the world,

not just to the affluent,

but to the ordinary
citizens of many countries.

- Jet engines and commercial
aviation are married

in a really interesting way
because now you're looking

at the ability to carry
hundreds more people.

- [Narrator] From the
post World War II era.

The DC3 airliner was able
to carry 21 passengers,

but as aviation technology
advanced, larger aircraft

came into play.

Fast forward to the 1970s and
the introduction of the 747,

capable of carrying
almost 400 passengers

in a single flight.

- That's amazing.

The airlines are making money
hand over fist and the ticket

prices are much cheaper.

So a ton of people are able to
fly in a way that they never

would have been able to before.

Jet engines have really
underpinned and revolutionized

commercial air travel.

- [Narrator] For air
travel to be an attractive

method of transportation,

planes need to be capable of
tremendous speed as people want

to get to their destination
as quickly as possible.

While jet engines are
certainly not slow,

inventors looked to propellers
to usher in the concept of

supersonic flight.

(exciting instrumental music)

- What supersonic flight
is is when you're traveling

at speeds faster than
the speed of sound,

which is 1,236
kilometers per hour.

So anything above that is
considered supersonic flight.

A bunch of really interesting
challenges occur when you

approach the speed of sound.

- When we started producing
aircraft at the beginning

of World War II, that were
capable of very high speeds,

we found that as those aircraft
approached the speed of

sound, they couldn't
actually go any faster.

And this actually had a
lot to do with propellers.

Basically, as you get
going faster and faster,

the drag on the tip of the
propeller and the speed of the

tip of the propeller
become the limiting factor.

So engineers and
scientists realized

that there was this barrier,

the sound barrier that
aircraft couldn't get past.

To this end, the US undertook
the Bell X-1 project.

This was a project to try
and break the speed of sound.

(exciting music)

- [Narrator] In 1947,

the Bell X-1 became the first
airplane to fly faster than

the speed of sound,

achieving a peak speed of
almost 1600 kilometers per hour.

- It really does look like
a human bullet with wings.

It is bright orange,
a straight wing.

It didn't actually take off
from the ground and then go and

break the sound barrier.

It was actually carried
in the belly of a B29

Super Fortress and then dropped

and then it used its own
rocket engine to achieve

the breaking of
the sound barrier.

But this was dramatic.

It was uncertain if this
could even be possible,

would the aircraft actually
survive and certainly the pilot

survive at that level of speed.

- [Narrator] The 1947
flight would prove to be

one of the most important
stories in the history

of aeronautical engineering.

- We have these speed limits
in our mind that perhaps limit

our creativity of
what's possible.

And then the Bell X-1 comes
around and shows us that it's

actually possible to go
faster than that limit.

And I think that unlocks our
creativity to be able to come

up with things to do
that we just didn't think

was possible before.

- It really does
usher in a new era.

And obviously there's military
applications and then people

naturally kind of
take that, you know,

from the military context
and it's just like,

"Oh, well, can that work
in commercial aviation?"

'Cause there may be something
interesting in supersonic

transport for civilians as well.

- [Narrator] Although it
was a major breakthrough

in supersonic flight,

it would still be
several decades before
flying faster than

the speed of sound would
be adopted commercially.

(inquisitive music)

Today, NASA's top
aviation innovators

are working at the Armstrong
Flight Research Center

in California where they're
developing and testing

the incredible
planes of tomorrow.

The X-57 Maxwell all
electric aircraft

is breaking industry barriers.

In 2022,

lithium ion battery packs
were successfully installed to

power the plane's motors,

bringing it one step
closer to its first flight.

The Armstrong teams are also
continuing to work on the X59

supersonic aircraft.

Prior to installing its engine,

teams assembled
other key elements,

including the tail and the nose,

inspired by the world's first
supersonic aircraft soaring

above the clouds
five decades ago.

- As aircraft evolved,

we wanted to get places
faster and faster and faster,

and in the 1970s it
became technologically
feasible to build

transonic aircraft,
aircraft that can go faster

than speed of sound
and carry passengers,

and that's where the
Concorde comes in.

It was really a craft that
was designed to move people

transatlantic in a very
short period of time.

Instead of taking 6, 7, 8
hours to go from New York

to London or to Paris,

you could do it in
three and a half hours.

This is a really
big step forward.

It's bringing those continents
closer and closer together.

- The Concorde was
jointly developed by

British and French engineers,

and it was at the time the peak
of air travel and affluence.

- The basis of this agreement
was we're going to build two

prototypes, one in
England, one in France.

The costs ended up ballooning
to somewhere in the vicinity

of a billion pounds,
but people were excited.

This whole concept was something
that everybody was watching

with great interest.

President Kennedy was rather
envious of this whole situation

and was pushing American
companies like Boeing to create

their own supersonic
airliner in order to compete.

The Russians developed
the Tupolev Tu-144,

which looked suspiciously
like the Concorde,

but unfortunately that
never panned out either.

So in terms of supersonic
transportation,

I mean the Concorde is it.

- [Narrator] The Concorde
had a very unique look,

a result of some very
calculated engineering.

- It had a very
aggressive angle of attack

for its wings that

actually resulted in it needing
to have something called a

droop snoot, which is
the nose of the plane.

It had to be pointed down at
such an angle to allow for

better visibility.

- With swept wing aircraft
designs like the Concorde,

you have to have a really steep
approach angle to maintain a

knot lift from the wing.

So basically you can't come
in really shallow like this.

You've gotta almost
drop out of the sky.

The problem with that is that
the pilots can't actually see

the runway when the nose of
the aircraft is pointing up.

So to address this issue,
the Concorde had a drop nose.

Basically the nose could be
pointed downward so that the

pilots could see the runway
while they were approaching the

runway at these
really steep angles.

- [Narrator] As a result
of its droop snoot,

it ended up requiring
two windshields,

one fastened to the
movable nose and the other

secured onto the cockpit.

In designing supersonic
aircraft, like the Concorde,

engineers are forced
to contend with a very

specific issue,
aerodynamic heating.

- When we achieve
extremely fast travel,

one of the things that we are
concerned with is the buildup

of pressure along the faces of
the aircraft and that buildup

of pressure amounts
to increases in heat.

Heat could cause
material failure.

Essentially, when we raise the
temperature of any material,

what we're doing is
we are changing the
underlying structure

or behavior of that material.

- This phenomenon
caused the Concorde

to expand a staggering
15 to 25 centimeters

at its cruising speed of Mach 2.

- Another important design
feature of the Concorde were the

composite materials that
made up its fuselage.

These materials were custom
designed to deal with the

extreme amounts of heat
over and above what a normal

commercial aircraft
would be experiencing.

- Steel is too heavy versus
aluminum is three times lighter.

So aluminum in its purest
form, it's just aluminum,

it's soft, it is
easily bendable.

But when you add copper
to it, like 4% copper,

its strength
increases five times.

Now people thought, "Oh,
okay, this is good".

But there is something more
that can be done to this.

It's called
directional properties.

Metal, when you pull it,

it'll pull, it'll
stretch, it'll deform,

but when you knock a metal,
it's not gonna break.

That's the difference
between ceramic and metal.

Ceramics are brittle,
they shatter,

but when you pull a ceramic,
it's actually very strong.

So you marry the boat.

If I can make the ceramic in
nano sizes and weave it into

this metal part, I
make a composite.

So once I start
putting composites in,

now I get this
enormous lightweight,

but the strength is super good
because now I'm putting these

ceramic particles.

Now where can I use it?

Planes.
- In designing the Concorde,

materials that were
used were aluminum based

alloys, steels,

some stainless steels in the
form of some honeycombs and a

composite resin.

- The Concorde was painted
with a white reflective paint

that would try to dissipate and
deflect as much of that heat

as possible,

but the walls of the cabin
were warm to the touch.

So that was something
that even as a passenger,

you could feel.

- [Narrator] Many of
the groundbreaking
composite materials

used in today's aircraft
weren't widely available

or viable 50 years ago when
the Concorde was in its heyday.

And these materials are crucial

to future supersonic success.

One of the front runners in
this new supersonic race is the

Boom Overture.

- The overture supersonic jet
concept is really interesting.

It takes what the Concorde had
and moves it into the modern

era with modern materials.

And what we've seen in the
last 20 years is an evolution

away from aluminum materials
moving into composites.

And composites are really
great materials because we can

engineer them for
specific purposes.

- One of the biggest problems
with supersonic flight is what

actually happens to this
materials mid-flight.

In the case of the Overture,

it's been designed to
have a very low CTE,

or coefficient of
thermal expansion.

This means that it can
endure the high friction,

high temperature that
is associated with
supersonic flight

without actually changing
its length or shape.

- So with the Overture,

we're able to design composite
materials for different parts

of the aircraft.

We can use composites that
form the spars that support the

wings and support the fuselage,

which are very
temperature resistant.

So we can design an aircraft
that is still very lightweight,

but meets all the
material requirements

for supersonic flight.

- [Narrator] The Overture
will be the world's fastest

sustainable passenger jet,
to support its Mach 1.7

cruising speed, the
Overture will be running

on 100% sustainable
aviation fuel

boasting a 7,871
kilometer range.

The aircraft is meant to carry
between 64 and 80 passengers

as opposed to the
Concorde's 100 passengers.

- But it's meant to be
about 75% more affordable.

Their goal is to be
delivering these aircraft

by the end of the decade.

(light ambient music)

- [Narrator] If the
Concorde had had access

to the superior
materials of today,

who knows how long it could
have remained in the skies.

Not only was it
incredibly innovative,

it was also a symbol of
luxury and affluence.

- It was the very height
of glamour in aviation.

So we talk about this jet age
aesthetic and the Concorde

really embodies this and it
kind of takes it to the next

level actually.

- [Narrator] The jet
famously helped Phil Collins

perform concerts in London and
Philadelphia on the same day.

The flights were
also historically
extremely expensive.

A round trip on the Concorde
for a three and a half hour

flight between New York and
London could cost about $10,000.

But despite all its
impressive elements,

the Concorde had one big
loud factor working against

its success, the sonic boom.

(airplane booming)
(fast paced music)

- As aircraft move through
the sound barrier and pressure

builds up on the
front of the aircraft,

and this produces shock waves
that produce the sonic boom.

The sonic boom sounds
like a thunder clap.

Imagine all the aircraft
over North America or Europe

producing sonic booms.

We basically have
continuous thunder claps.

So for this reason,

the Concorde was really limited
to only going supersonic

over the Atlantic Ocean.

It really couldn't go faster
than the speed of sound

over land.

- [Narrator] Sonic
booms are not only loud

and disruptive to civilians,

but they're also known
to shatter windows

and cause injuries.

- And while you need to
be pretty close to it

in order for it to have
devastating effects

in terms of breaking all the
windows and things like that,

the noise itself was a major
concern for over land flight.

- [Narrator] As a result,

supersonic flight was banned
over cities in the US and most

other countries.

(light ambient music)

- One of the other
drawbacks of traveling

at supersonic speeds is drag.

The faster and faster
we go in an aircraft,

the more the resistance
is to travel.

So the Concorde was
almost a flying fuel tank.

It took a lot more fuel per
passenger to convey people

across the Atlantic.

So it was a very
expensive flight,

used a lot of fuel,

and really wasn't very
environmentally friendly.

- [Narrator] With the
restrictions faced
by the Concorde,

commercially, it was
becoming less viable.

Then a disaster struck.

The year 2000 saw the
beginning of the end of this

supersonic aircraft.

- The couple of final nails
in the Concorde's coffin

was this massive instant at
the Charles de Gaulle Airport

where a piece of metal

that was on the runway got
flung up, burst a tire,

and then eventually that
hit the fuel tank and

caused a massive explosion.

- [Narrator] All 100
passengers and crew on board

were killed and the
Concorde fleet was grounded.

After investigations,

the fuel tanks on all the
aircraft were reinforced

just a year after the disaster,

Concorde was allowed
to fly again.

- The return to
flight happened to be

on September 11th, 2001.

After 9/11, you know,

air travel had just plummeted
and so not only were they

struggling to fill the
airplane in the pre 9/11 times

in the post 9/11 times,
it was almost impossible.

So it took about another two
years and then the Concorde

was finally put to rest.

- [Narrator] Today, in the
US and other countries,

commercial supersonic
flight is still forbidden

over most land.

But as we move towards a
future that includes supersonic

commercial flight,

governments are beginning
to implement changes.

In 2020,

the FAA established a
designated corridor over Kansas

where civilian supersonic
aircraft could be tested.

- We are going to go back
to supersonic flight.

It's going to happen.

These technologies are at
the cusp of becoming reality.

(exciting music)

- [Narrator] NASA has teamed
up with Lockheed Martin

to silence the boom.

- NASA's recognized that humans
need to return to supersonic

commercial flights.

To this end, they've
developed the X-59.

The X-59 is a testbed aircraft
designed to determine whether

supersonic flight over populated
centers can be done without

producing significant
disturbance to residents

due to a sonic boom.

- You need to figure out a way
to change the shape of your

aircraft to extend the shockwave
across the the aircraft,

stretch it out to
make that quieter.

The X-59 has an extremely
pointy, extremely long nose.

It doesn't even
have a windscreen.

There's a set of
cameras on the outside.

The wings are dipped a little
bit toward the fuselage of the

aircraft, and that again,

is all about smoothing
out that air flow.

And it's all in the
goal of taming the boom,

keeping the boom quiet.
(plane roaring)

- [Narrator] As we
look to the future,

there are even more
innovations on the horizon.

- There's a lot of
things happening in
the aviation industry

to push us into the next
generation of aircraft.

We're looking at ram
jets and scram jets.

What can actually
power aircraft to many,

many times the
speed of sound, 10,

15 times the speed of sound.

You take this jet,

you fire it up into
the stratosphere,

you engage your scram jet and
travel in suborbital flight

around the globe,
you have no noise.

You don't have a sonic boom
'cause you're outside the

atmosphere and you can travel
at extreme speeds without

actually burning any fuel.

You're actually kind
of coasting in space.

You don't have that drag.

It might be possible to
travel from New York City to

Australia in five hours.

- But in terms of the
future for aircraft

as we have them now,

I'm very interested in seeing
the revolution to more green

energy sources.

- There are now
actually commercial
aircraft using batteries

as the power source
for short flights.

We recognize that
with battery power,

we can use alternative fuels
like wind and solar to generate

the power that
charges the batteries.

By doing this,

we could reduce the carbon
footprint of aircraft.

- [Narrator] Although some
experts estimate we are still

30 to 40 years away from
perfecting the technology.

The more optimistic estimates
predict hydrogen will be

powering both mid range
and long haul flights

as early as 2035.

- With our current
interconnectivity,

our computer modeling
and our knowledge

from the past 100 years.

I can only imagine that what
we'll accomplish in the future

will just be exponentially
greater than what we've

accomplished in the past.

(exciting music)

(exciting music continues)