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If you haven’t been paying attention you have
not noticed the revolution happening in the
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airline industry. The days of attempting to build
bigger and bigger airliners like the 850 passenger
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double decker a380 and the 660 passenger humped
747 are gone. The behemoths are simply being
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outcompeted by a new generation of planes. Many
may mourn the slow demise of these iconic planes,
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but you are benefiting from this
change. The entire nature of air travel
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has changed to benefit you and your needs.
Your local airport has more direct flights
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to distant lands than ever before, and
the prices of those tickets are cheaper
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than ever. Connecting flights are becoming rarer
and rarer as this new breed of plane takes over.
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The plane at the forefront of this revolution?
The 787 dreamliner. A 30 billion dollar bet
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on the future of the airline industry. [1]
Boeing sat at the poker table and pushed all
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their chips forward. An all-in bet on
a radical new future, and it paid off.
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The 787 revolutionized not only
how the airline industry operates,
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but how future planes will be designed and built.
This is the breakdown of the 787’s materials.
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By weight, 55% of the 787 is made from composite
materials, like carbon fibre reinforced plastics,
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making it the first commercial airliner
made primarily from this new age material.
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The 787 is rivalled only by the Airbus A350XWB,
introduced 4 years after the 787 in 2015. [2]. So,
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why are composite materials so desirable
for the airline industry and how has the 787
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made the most of their advantages?
Composite materials are made up of two or more
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materials. Take carbon reinforced plastics. These
are composed of extremely strong carbon fibres
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bound together by a plastic resin. Carbon fibre,
made up of thousands of tiny thin fibres of
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carbon, is incredibly strong in tension. Up to 5
times stronger than steel, and one fifth of its
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weight. [3] But these tiny fibres can’t create a
solid part by themselves. This is an image of a
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human hair beside a carbon fibre, the carbon fibre
is the smaller one, and just like a human hair
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they can bend and flex and separate very easily.
So, we need to first bind them together with a
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plastic resin to form a solid material, otherwise
they just form a strong, but flexible fabric.
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That flexibility as a fabric is exactly what makes
composites so useful when creating the precise
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and elegant curves of an aircraft. With the right
tooling and designers, composite components can
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be made into almost any shape imaginable.
In the past, a disadvantage of making large
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aircraft components from composites was
the time taken to manually lay-up parts.
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Where layers of carbon fiber and plastic resin had
to be carefully constructed. It required skilled
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technicians and was inherently difficult to
scale to the production quantities Boeing needed.
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To get around this problem Boeing uses automated
tape laying to produce massive aircraft sections.
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The 787s fuselage is created by wrapping a carbon
fibre tape impregnated with a plastic resin around
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a rotating mould of the fuselage. This machine
precisely controls the overlaps of the tap and
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the orientation of the fibres to ensure we get the
most out of the carbons tensile strength to resist
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the internal pressure loads and the longitudinal
bending loads the fuselage will experience.
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One of the problems with this manufacturing method
is that this part needs to be placed inside an
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oven to cure the resin. This hardens the plastic
and creates a solid composite structure. Ovens
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the size of a wide body jet airliner fuselage
are not exactly common, and this is often the
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limiting factor on parts made this way
and requires massive upfront investment
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to build a customized oven large enough to fit
the part, but the benefits are well worth it.
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The first and most obvious is the strength carbon
fibre provides. Previous generation airliners are
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typically pressurised to an equivalent pressure
of 8,000 feet. [4] That’s the same height as
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Mount Olympus in Washington State. High enough
that the lower pressure would reduce your oxygen
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intake and your stomach will bloat as the air
inside is higher pressure than the outside.
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This is uncomfortable and exacerbates the effects
of jet lag. Thanks to the 787s stronger fuselage,
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it can increase it’s internal air pressure to an
equivalent of 6,000 feets. 25% lower in altitude,
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and about 7.3% higher in pressure. [5] It may
not sound like a lot, but it goes a long way
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in making the journey more comfortable, at
the very least the person next to you won’t
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be farting as much. Less farting is always nice,
but my favourite benefit of the stronger fuselage
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is the absolutely massive windows.
This is the 787 window, and these are windows
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of some equivalent aluminium airliners. They are
absolutely massive. In aircraft made primarily
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of aluminium, having holes this large in metal
panels would result in the build up of stress
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at the window boundaries, as the stress
contours have to deviate around the window.
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This stress does not exceed the material's
strength, but over repeated pressure cycles
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tiny imperfections in the metal can grow into ever
larger cracks and eventually fail. [6] Holes this
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large in an aluminium airliner would severely
shorten the plane's flying career before it
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needed to be fixed or disposed of, kinda like
cracks in McGregor's leg shortened his career,
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but it’s not a problem for the 787 thanks
to composites' relative immunity to fatigue.
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You could kick Dustin Poirier’s knee cap as
many times as you like with carbon fibre shins.
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The carbon fibre construction provides plenty
of benefits for the airline operators too.
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Because the fuselage is just one massive part,
Boeing was able to eliminate all joints and
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the fasteners needed to join them together.
Sections that used to be made up of 1500
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aluminium sheets riveted together using 40 to 50
thousand fasteners are now just one massive carbon
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fibre section.[7] Carbon fiber's strength to
weight ratio already makes the fuselage lighter,
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but eliminating joints and fasteners
makes it even lighter again.
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The reduced weight reduces fuel burn. This
fuselage is also incredibly aerodynamic because
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it doesn’t have thousands of little bumps and
ridges all over it from those joints and rivets.
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Animation 5a
These surface imperfections make the
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plane’s surface rough and cause it to disturb
more airflow, increasing parasitic drag. [8]
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Composite materials help reduce drag in other
ways. One of my favourite things about the
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787 is its extremely thin and elegant wings.
The main structural member of a wing is the wing
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spar. It’s primary role is to resist the upwards
bending forces during flight. It’s essentially
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just an I beam, a shape optimized to resist
bending loads. The wing spars of the 787 are
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constructed from carbon fibre composite, while the
ribs, the structural members connecting the two
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ribs that support the wing skin, are machined out
of solid aluminium plates. [9] The structure the
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rear and forward wing spars form with ribs running
between them is called the wing box, and it forms
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the main load bearing structure of the wing, while
also being a literal box for fuel to be stored.
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The carbon fibre spar provides the wing
fantastic strength. Strength is quantified
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by the force required to completely fracture
a material, but carbon fibre composites have
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another important quality that makes them perfect
for aircraft wings. Their maximum elastic strain.
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There are two types of deformation. Elastic and
plastic deformation. Elastic means the material
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will snap back into its original shape after
the load is removed, like an elastic band.
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Plastic means it will be permanently deform
and won’t return to its original shape
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once the load is removed. Something we don’t
want happening. This is permanent damage.
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Carbon fibre composites can deform further
before they strike this plastic deformation zone,
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at about 1.9% [10] while aircraft aluminium
begins permanently deforming at less that
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1% [11]. That means we can bend carbon composites
further before we need to worry about permanently
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deforming them , and that means we can make our
wings super flexible. During flight the wing tip
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of a 787 can move upwards by 3 metres, that sounds
a lot, but in order to get certified by the FAA
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every plane needs to be able to handle 150%
of the planes absolute maximum expected load
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during flight for 3 seconds, and during that test
the 787s wing bent upwards by 7.6 metres. [12]
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That’s a great deal of bending, despite carbon
fibre composites being stiffer than aluminium.
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Meaning, it takes more force to deform the
same volume of material, but critically,
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787 wings are not the same shape as their
aluminium counterparts. This ability to withstand
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greater bending allowed engineers to make the
787s wings with a higher aspect ratio. [13]
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Aspect ratio is the ratio between
the wing span and mean chord,
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or wing width. A high aspect ratio would
be a long skinny wing like a glider,
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while a low aspect ratio would
be a delta wing of a fighter jet.
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A traditional airliner has an aspect ratio of
about 9, like the 787s predecessor the 777,
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but the 787 has a massive aspect ratio at
11. [14] This is what causes the 787s wings
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to flex so much during flight.
Composites are actually much stiffer
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than aluminium, but their ability to withstand
high deformation allowed the engineers at Boeing
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to create a much higher aspect ratio wing,
a longer narrower wing that would bend more,
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but this comes with some huge benefits.
The planes with the highest aspect ratio
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are gliders. For an unpowered plane the
highest priority is minimizing energy lost
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to drag. This allows the glider to stay in the
air for extended periods with no engine. These
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types of aircraft typically have aspect ratios
greater than 30, and these aircraft have the
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lowest drag penalties as result of vortex drag.
This is the drag caused by air mixing from the
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high pressure zone under the wing with low
pressure air above the wing, forming votives
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at the wing tip, by spreading the area of the wing
over a longer span we minimize the pressure that
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drives this mixing at the wing tip, and thus
minimizes the energy lost to the vortices.
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Normally higher aspect ratio wings have lower
internal volumes. For an unpowered glider this
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isn’t an issue, but for a plane that needs that
storage space for fuel it is. Less storage volume
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for fuel means lower range, and one of the primary
goals of the 787 is to be an efficient long range
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aircraft, capable of allowing airliners to open
new routes that were once deemed impossible.
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Thankfully modern planes like the 787 use a new
kind of aerofoil. The supercritical aerofoil.
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Older aerofoils looked something like this. A
reasonably symmetric design with a sharp nose
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and gentle curves on the upper and lower
surface. This is a supercritical wing. The
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leading edge is blunter with a larger
radius, the top is relatively flat,
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and the lower portion has this strange cusp at the
back. This aerofoil has much more useful internal
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volume thanks to it’s blunt leading edge
and larger thickness to chord ratio. [15]
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Helping solve our low internal volume problem
associated with high aspect ratio wings.
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The supercritical wing was first tested
by NASA on a modified TF-8A Crusader,
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and you can really see the similarities in design
ethos between this experimental plane’ s sleek
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wings with the 787s. But increased internal volume
is not why NASA developed the supercritical wing.
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NASA developed it to delay the onset
of shock wave formation over wings.
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When air travels over a wing, the air on top
accelerates. This means that even though the
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plane itself might be travelling below the
speed of sound, the air over the wings may
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break it and create a shock wave. This shockwave
decreases lift and causes an increase in drag,
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this kind of drag is called wave drag and planes
need to fly below the speed this occurs at.
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This speed is called the critical mach number.
The supercritical wing was designed to increase
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the critical mach number. [16]The flat
top of the supercritical wing means the
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air does not accelerate as much as
it would over a classic aerofoil.
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Ofcourse, this causes a loss in lift because that
fast moving air is causing a drop in pressure on
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top of the wing. To compensate, supercritical
aerofoil has this concave curvature underneath
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the wing which causes an increase in pressure
there to compensate, this increase in pressure
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does not affect the critical mach number. While
the larger radius of the leading edge increases
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the lift generated at higher angles of attack.
This is because air struggles to follow the
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tighter turns of a smaller radius leading edge,
which causes earlier flow detachment and stall.
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The larger radius delays this flow separation.
This aerofoil shape changes continually as you
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travel the length of the wing. Twisting and
curving in computer calculated precision.
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Optimizing the wing shape to be as efficient as
possible, and the use of composites provided the
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engineers with the confidence that these shapes
could be manufactured. The skin is simply laid
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down on a mould with automated tape laying once
again, we don’t have to beat metal into shape each
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and every time we want to recreate these delicate
curves. The fibres of the wings have even been
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laid in a specific pattern to tailor the stiffness
of the wing in different areas. This means the
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wing deforms exactly as the 787s engineers want
it to as it gains speed. [17] So the wings shape
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actually changes during flight to better suit
the needs at different speeds. This is called
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aeroelastic tailoring and is the forefront of
state of the art aeronautical engineering today.
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The 787 also features a novel device designed
to reduce turbulent flow over the tail of the
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aircraft.Two types of flow states exist
in aerodynamics: Laminar flow occurs at
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low velocities and is characterised by fluid
layers flowing smoothly over each other in neat
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orderly layers. Laminar flow is predictable and
non-erratic and does not create significant drag.
00:16:13
Turbulent flow is far more common but still
very little is known about how to predict its
00:16:18
behaviour. It is very difficult to control because
of the formation of small vortices called eddies
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in the flow, making the flow highly erratic.
Turbulent flow occurs at higher flow velocities
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and causes a significant increase in drag.
At cruising speeds of 80-85% of the speed
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of sound , turbulent flow is ultimately
unavoidable, but we can work to minimize it.
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Boeing has developed a technology that helps them
delay and control the formation of turbulent flow
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called Hybrid Laminar Flow Control. Details on
their implementation of the technology are sparse;
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this technology is capable of reducing
fuel burn by as much as 30% [18], and so
00:17:01
companies are keeping their research extremely
secretive to keep their competitive advantage.
00:17:06
Here’s what we know. In the late 80s and early
90s NASA and Boeing began investigating a suction
00:17:13
system on the 757 that would draw in boundary
layer air, that is the layer of very slow moving
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air that clings to the surface of moving objects.
It looked something like this [19]. The outside
00:17:24
skin of the surface was permeable to air through
tiny perforations, too small for the naked eye to
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see. Manufacturing the permeable surface, while
also keeping the tiny holes clear of debris is
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one of the many challenges with this technology.
The outer and inner skin were then attached to an
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elaborate plumbing system that was connected to
a turbopump which sucked air from the boundary
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layer of air that would form along the plane’s
surface. By doing this they could drastically
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delay and reduce the size of the turbulent
flow, and in turn reduce the drag on the plane.
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There is no space for this ducting system inside
the wings of the 787, but from what we do know it
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is inside both the horizontal and vertical tails,
however the only clue of their presence are these
00:18:10
little doors, who’s purpose are a mystery to me
with little to no information available online,
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a testament to how advanced this plane is. [20]
Composites give plenty of advantages,
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but it does come with some disadvantages.
When we examine the plane’s composition. One
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material jumps out at me. 15% of this plane
is titanium, that’s much higher than normal.
00:18:34
Titanium is an expensive material, so they must
have had a good reason to use it over aluminium.
00:18:41
Aluminium is typically corrosion resistant when
left on it’s own, but when it is placed in direct
00:18:47
contact with carbon fibre composites, something
strange happens. The aluminium begins to corrode
00:18:54
incredibly quickly. Something about carbon fibre
causes aluminium to oxidize and fall apart.
00:19:01
Carbon fibre is like aluminiums kryptonite. [21]
This phenomenon is called galvanic corrosion, and
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it happens when two materials that have dissimilar
electric potentials or nobilities are placed in
00:19:14
contact with an electrolyte, like salt water.
[22] If we take a look at the galvanic series,
00:19:20
which quantifies materials nobilities, we can see
that graphite is very noble, on the far end of the
00:19:27
left scale, while aluminium is quite far to the
right. [23]When this occurs an electric potential
00:19:33
forms between the two materials that causes the
two materials to trade electrons and ions, which
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results in the anode being eaten away. This effect
is made even worse when the surface area of the
00:19:47
more noble material, the cathode, is very large in
comparison to the less noble material, the anode.
00:19:54
Say for example, when carbon fibre components
are fastened together using aluminium fasteners.
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To avoid this corrosion the engineers
needed to pick a material closer to
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carbon in the galvanic series, and the
closest suitable metal was titanium.
00:20:11
This has been a huge source of cost in
manufacturing, Boeing’s production cost was higher
00:20:16
than it’s sales price for quite some time. Meaning
they were making a loss on each aircraft sold.
00:20:23
This is fairly typical for new airliners,
as R&D and manufacturing tooling costs
00:20:28
take time to recoup and companies like Boeing
typically spread these costs over a period of
00:20:34
time on each plane,instead of just having a
massive negative balance sheet in one year,
00:20:40
but because the 787 was so radically new, these
sunk developments costs, called deferred costs
00:20:47
were expected to reach 25 billion before Boeing
even reached a breakeven point on each plane
00:20:54
sold. Where the cost of manufacturing equaled
the sales price. In comparison the Boeing 777
00:21:01
reached 3.7 billion [24] To recoup costs as fast
as possible it was essential that Boeing reduced
00:21:08
the cost of production, and high on their list was
the elimination of titanium parts where possible.
00:21:14
The frame around the cockpit windows for example
were initially made out of titanium, but were
00:21:20
changed to aluminium with a special coating to
prevent corrosion. While some parts that were
00:21:25
originally titanium were changed to composites
like door frames. [25] Other improvements were
00:21:31
sought to make the manufacturing process for
titanium less costly. Many metallic parts used
00:21:37
on aircraft start off as large blocks of metal
that have been machined down into their final
00:21:43
shape. This results in a tonne of wasted metal
as the metal is gradually shaved away. Aircraft
00:21:49
manufacturers quantify this wastage with something
called a buy to fly ratio, and it’s a huge source
00:21:56
of increased manufacturing costs. One Boeing
has tackled this is by collaborating with Norsk
00:22:02
Titanium, a titanium 3D printing company.[26]
Now making 3D printing metal parts is not easy.
00:22:10
Most titanium 3D printing involves a powdered
titanium that is melted together using lasers.
00:22:16
Researchers used special high speed x-ray imaging
to visualize what happens during this process
00:22:22
and found a lot of imperfections.
The track varies in height,
00:22:26
the powder gets blasted away resulting in varying
thickness and separated tracks that coalesce and
00:22:31
even bubbles causing pores in the metal. This
creates parts with a lot of micro-imperfects
00:22:38
and imperfections that lead to decreased
life as fatigue causes cracks to form.
00:22:43
We can visualise a material's fatigue
strength by plotting on a S-N curve,
00:22:48
which places the magnitude of the alternating
stress on the Y-axis and the number of cycles
00:22:53
it survived on the x-axis. For traditional
machined titanium it looks something like this,
00:23:00
whereas for 3D printed parts it looks like this.
[27] 3D printed parts simply fail much sooner
00:23:07
because of these tiny imperfections. Norsk has
worked to improve this. Instead of using laser
00:23:13
sintering with powder, Norsk have developed a
revolutionizing patented wire based metallic
00:23:20
3D printing system for titanium that they
monitor with 600 frames per second cameras
00:23:26
for quality control. These 3D printed parts are
then machined down into the final shape, reducing
00:23:32
the total titanium used by 25-50%, and their
printing method is 50 to 100 times faster than the
00:23:40
powdered printing method. This process resulted
in the first ever FAA certified 3D printed
00:23:47
structural components and they first flew in the
Boeing 787.[26] This plane truly is innovative.
00:23:56
Titanium was not the only
material Boeing worked on removing
00:23:59
from the plane's construction to save on cost.
Copper once formed an important part of the 787s
00:24:06
wing, where it was laid down in thin strips on
the wing's surface. This is not a typical design
00:24:12
choice for aircraft wings, and once again it was
influenced by the 787s composite construction,
00:24:19
because composite materials
are not good conductors.
00:24:23
Carbon fibres are great conductors, but
problems arise because of the plastic resin
00:24:28
binding them together, as this resin is
an insulating material, preventing the
00:24:33
passage of electricity. [28] Animation 15a
Which is a massive problem for planes,
00:24:37
as getting hit by lightning is not a
rare occurrence. One study calculated
00:24:42
that lightning strikes occurred once every
3000 hours of flying between 1950 and 1975.
00:24:49
A 787 was struck by lightning while taking
off from Heathrow. Upon landing in India,
00:24:55
42-46 holes were found in the fuselage as a
result of resistive heating. [29] The plane
00:25:02
survived and was flown back to London
for repairs with no passengers aboard,
00:25:06
but composite’s vulnerability to this kind
of damage is a drawback and the repair
00:25:11
process is more complicated than with aluminium.
However, this strike could have been much worse,
00:25:18
if the electricity does not smoothly run along
the surface of the plane and exit, it may cause
00:25:24
a spark in the fuel tanks and cause an explosion.
This kind of accident was not uncommon in
00:25:30
the early days of the airline industry.
Like Pan Am Flight 214, which was struck
00:25:34
by lightning while it flew in a holding
pattern waiting for a lightning storm to
00:25:38
pass at Philadelphia International Airport
in 1967. It’s left wing fuel tank exploded,
00:25:45
causing the plane to barrel out of control
to the ground in flames. [30] Since then the
00:25:51
aviation sector has implemented rigorous safety
measures and lightning protection tests to ensure
00:25:57
an accident like this could never happen again.
Early 787 wings were designed with copper strips
00:26:03
to ensure the electrons had a path of low
resistance along the surface of the wing,
00:26:09
ensuring they wouldn’t travel to
the fuel tank and cause a spark,
00:26:13
while also preventing resistive heating damage
to the composite structure. Fasteners were sealed
00:26:18
with an insulating material to stop electricity
from travelling down the metallic fastener into
00:26:24
the fuel tank, and the fasteners themselves
were fitted with compression rings and a sealant
00:26:29
to eliminate potential spark locations caused
by gaps and sharp edges. Finally the 787 has a
00:26:36
nitrogen inerting system that fills the tank with
nitrogen; ignition can’t happen without oxygen.
00:26:42
Boeing has since removed two of these
protections in a cost saving measure,
00:26:47
removing the copper mesh and insulating caps,
which drew concern and criticism, but Boeing
00:26:52
argues that between the nitrogen inerting
system and the other safety measures,
00:26:56
these expensive features were not needed. [31]
Where composites couldn’t be used,
00:27:01
other materials were chosen. The leading
edges of the wing and tail, the tail-cone,
00:27:05
and parts of the engine cowling, were all made
from aluminium or other metals [5]. The leading
00:27:11
edges of the plane needed aluminium because of
the composites' poor impact resistance. While
00:27:16
composites have extremely high strength, they can
be brittle on sudden impacts such as bird strikes,
00:27:22
which most commonly happen at the leading
edges of the wing or on the engines.
00:27:26
Metals are able to deform on impact with a reduced
chance of fracture, instead of shattering as
00:27:32
composites would (Visual [4]). Aluminum leading
edges were also beneficial for the purpose of
00:27:37
de-icing because they are good thermal conductors.
If you have ever flown on a very cold day you
00:27:44
may have seen a truck spray fluid onto the
wings of the plane. This is de-icing fluid.
00:27:50
A heated mixture of glycol and water. It’s
needed because most planes aren’t capable
00:27:55
of de-icing themselves on the ground. The
787 can be, when fed with external power,
00:28:01
because it uses a new type of de-icing system.
The 787 uses electrically heated blankets bonded
00:28:07
to the surface of the slats [32] , which are
able to heat the surface of the wing and melt
00:28:12
or prevent any ice formation on the leading edge
of the wing. Traditionally, ice is prevented by
00:28:18
extracting hot bleed-air from the engine and
piping it to vulnerable areas such as the
00:28:23
leading edge of the wing where ice build up could
severely interfere with the wing's operation.
00:28:29
This draws valuable energy away from the
engines and increases fuel consumption,
00:28:34
while also requiring a complicated network
of tubing and exhausts which adds weight
00:28:39
and increases complexity of
construction and maintenance.
00:28:43
The electric heating system is twice as
efficient as the extracted bleed air system,
00:28:48
as no excess energy is lost through venting
air to the atmosphere, and it also reduces
00:28:53
drag as the exhaust holes for the bleed air
on the lower side of the wing create drag.[33]
00:28:59
The 787 is actually the first commercial airliner
that has eliminated this bleed air system,
00:29:05
which was a huge technical challenge and
required a complete redesign of several systems,
00:29:11
and an entirely new engine. In our next video we
are going to explore the incredible engineering
00:29:17
behind the power systems of the 787, exploring
the advancements in the jet engine and the overall
00:29:23
system architecture that allowed the 787 to become
the most efficient long range airliner ever made.
00:29:31
We will be releasing that video here on
YouTube shortly, but if you don’t want to wait
00:29:36
it’s already on Nebula ad free, or if you are like
me and like to sit back and watch longer videos,
00:29:43
we have created a special hour long
version that combines both videos and
00:29:47
have added extra information that didn’t
fit into either of the YouTube versions.
00:29:52
I have included links to both of those videos
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00:29:57
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If you are a fan of this channel,
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You can also get exclusive content from us
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or you could learn about my life before YouTube in
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00:30:48
Genesis. Where you can learn the story of how I
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00:30:54
“How advanced was the YouTube channel
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A little over 1 dollar a month. This is by
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With access to both Nebula,
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on screen right now, or if you are
looking for something else to watch
00:31:32
right now you could watch our last video
on how these vapor cones form on planes,
00:31:37
or you could watch Real Science’s video
on the insane biology of dragonflies.
