Original subtitles

(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)