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Aerodynamics Explained by a World Record Paper Airplane Designer | Level Up | WIRED
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hi i'm john collins origami enthusiast
and world record holder for the farthest
flying
paper airplane
[Applause]
today i'm going to walk you through all
the science behind five
stellar paper airplanes most of us know
how to fold
a simple paper airplane but how is this
flying toy connected to smarter car
design
golf balls or clean energy by unlocking
the principles of flight
and aerodynamics we could affect the
world on a massive scale
and by the end of this video you're
gonna see paper airplanes
on a whole different level
[Music]
so to understand how this flies we're
gonna have to go back
and look at this the classic dart
i'm going to walk you through the
folding on this really simple paper
airplane
the classic dart is just a few simple
folds done well
sharp creases are the key to any paper
airplane there's not a lot of
aerodynamics here so it's really just
about getting some folds accurate
too little adjustments are going to help
this plane or any paper airplane fly
better
positive dihedral angle and just a
little bit of up elevator
there are two key adjustments that will
help any paper airplane fly better
the first one is called dihedral angle
and that's really just angling the wings
upward as they leave the body of the
plane that puts the lifting surface
up over where all the weight is so if
the plane rocks to one side it just
swings back to neutral
the other thing is up elevator just
bending the back of the wings
upward just a little bit at the tail so
air will reflect off of that
push the tail down which lifts the nose
those two things will keep your airplane
flying
great let's see how this plane flies to
demonstrate
our producer is testing it in an
enclosed environment
with the main forces acting on this
plane to fly this plane will travel only
about as far as your strength can muster
before gravity takes over but that's the
problem
there's too little lift and too much
drag on this plane the ratios are just
all off
drag is the sum of all the air molecules
resisting an
object in motion that's why windshields
are now raked way back on automobiles
that's why airplanes have a pointy nose
to reduce drag
you want to cut down on the amount of
drag so that it takes less energy
to move forward and with any flying
machine even our paper airplane
drag is one of the four main aerodynamic
forces
the others are of course thrust the
energy that pushes an
object forward gravity which is of
course the force that pulls everything
toward the earth
and lift that's the force that opposes
gravity
and when all four of those forces are
balanced you have flight
here's how all these forces are acting
on the plane
when the dart flies through the air it
uses its narrow wingspan
and long fuselage with the center of
gravity positioned near the center of
the plane
to slice through the air molecules it's
very sturdy and flies very straight
the problem is it can only fly about as
far as you can chuck it before gravity
takes over
but once you put some aerodynamic
principles to the test you can find
clever ways to make the plane go farther
what if we tucked in some of the layers
to eliminate some of the drag
and expanded the wings to provide a
little more lift so that the plane can
glide
across the finish line rather than crash
into it and explode
so what do we need to make this plane
fly better more lift of course
but what is lift exactly for a long time
the bernoulli principle was thought to
explain lift
it states that within an enclosed flow
of fluid points of higher fluid speeds
have less pressure than points of slower
fluid speeds
wings have a low pressure on top and
faster moving air on top so
bernoulli right wrong bernoulli works
within a pipe an enclosed environment
faster moving air in this case does not
cause low pressure atop the wing
so what does to understand that we're
going to have to take a really close
look at how air moves around an object
there's something called the coanda
effect which states that
airflow will follow the shape of
whatever it encounters
let's look at a simple demonstration of
these two things
okay two ping-pong balls right faster
moving air between them
check the ping-pong balls move together
must be a low pressure right
wrong that's where it gets confusing
so as the air moves between the
ping-pong balls it follows the shape of
the ping-pong balls and gets deflected
outward
that outward shove pushes the ping-pong
balls together
inward what we're talking about here is
newton's third law
equal and opposite reaction so it's not
bernoulli that causes the ping-pong
balls to move together
it's that air being vectored outward
shoving the ping-pong balls together
inward let's see how that works on a
real wing
notice how the airflow over the wing
ends up getting pushed
downward at the back of the wing that
downward shove
pushes the wing upward and that is lift
so if the narrow wings on this dart
aren't providing enough lift
and the body of the plane is providing
too much drag what can we do
well we'll need to design a plane with
bigger wings that slips through the air
easily let's take it to the next level
this is a plane i designed called the
phoenix lock just ten folds
it's called the phoenix lock because
there's a tiny locking flap that holds
all the layers together and that's gonna
get rid of one of the big problems we
saw with the dart where those layers are
flopping open in flight
now what you'll see here in the finished
design is that we've done two things
made the wings bigger and brought the
center of gravity forward a little more
making the lift area behind the center
of gravity bigger as well
it's a glider versus a dart normal
planes have propulsion systems like
engines that supply thrust
gliders on the other hand need to
engineer in a way to gain speed
and to do that you need to trade height
for speed
let's take a look at what's happening
with the new design with the center of
gravity
more forward on the plane this plane
will point nose down
allowing you to gain speed that's lost
from drag
and then when the plane gains enough
speed just enough air to flex off of
these tiny bins at the back of the plane
to push the tail down
which lifts the nose up and that's how
the plane achieves a balanced
glide what the bigger wing area does is
allow for better
wing loading now wing loading contrary
to popular belief
is not how many wings you can stuff in
your mouth before snot starts coming out
of your nose
no wing loading is really the weight of
the whole plane
divided by the lifting surface in this
case the wings of the plane not
not buffalo wings high wing loading
means the plane has to move much
faster to lift the weight low wing
loading means the plane can fly
slower to lift the weight since each
plane is made out of the same
paper the weight is constant the only
thing that's really changing here
is the size of the wings and that's
what's changing the wing loading
think about things in real life where
this applies look at a monarch butterfly
really lightweight design right it's an
insect doesn't weigh much and it's got
giant wings it just kind of floats
slowly through the air
and then look at a jet fighter really
fast
really small wings just made the slice
through the air at high speeds
that's really the difference in wing
loading here big wings
slow small wings fast now let's go one
step further and see how
wind loading can affect the distance in
flight watch what happens when the
phoenix flies
it just glides more in that distance
that it moves forward for every unit of
height that it drops
that's called glide ratio or lift to
drag ratio
applying this to planes in real life an
aircraft might have a glide ratio
of 9 to 1. that's roughly the glide
ratio of a cessna 172 so that means
if you're flying that cessna and your
engine quits at an altitude of 100
meters
there better be an airfield or a cow
pasture less than 900 meters away
or you'll be in real trouble modern
gliders can have a glide ratio as high
as
40 to 1 or even 70 to 1. hang gliders
have a glide ratio of around 16 to 1.
red bull flutaw gliders maybe have a
glide ratio of one to one but that's
really more dependent on the ratio of
red bull to red beers in their stomachs
when they were
designing their aircraft now we have a
plane with much bigger wings that slips
through the air
a lot better so we can use that thrust
to gain a lot of height
and then efficiently trade height for
speed that is
use all that thrust to get some altitude
and use that efficient glide ratio
to get some real distance but there's a
new problem
this plane just can't handle a hard
throw we're gonna need a good amount of
thrust to get it to go the distance
so if the dart held up to a strong throw
but had too much drag
and the phoenix did really well with a
soft throw but couldn't handle the speed
what we're gonna need is something
that's structurally sound that can
handle
all the thrust and still have a wing
design that will allow us to create
efficiency
that will go the distance let's level up
this is the super canard the folding on
this deliciously complex
squash folds reverse folds petal folds
really interesting folding
it requires a high degree of precision
accurate folding and
symmetry and what's special about it is
it's got two sets of wings a forward
wing and a rear wing
and that's going to make the plane stall
resistant we'll talk more about that in
a moment
we can see a few things here center of
gravity is in front of the center of
lift
check can it hold together with stronger
thrust yes
the winglets actually create effective
dihedral making the wingtip vertices
shed more cleanly
and control left right roll better
making it more stable in flight
wing loading well the interesting thing
is you can see the design of the dart
inside the canard and what it looks like
we've done is added more wing area to it
however the canard design is much
smaller than the dart so we're not
getting a big advantage here in terms of
wing loading
it's very sturdy so it can handle a lot
of thrust so we're hoping it can go the
distance but what's really cool about
this plane
is that it's stall resistant let's take
a look at what a stall
actually is on a wing a stall is caused
either by
too slow of an air speed or too high an
angle of incidence
remember the koanda effect the coanda
effect is the tendency of a fluid to
stay attached to a curved surface
when air travels over a wing it sticks
to the surface and
bending flow results in aerodynamic lift
but when a plane is traveling with too
high
an angle of incidence the air can't
adhere to the surface of the wing so
lift is lost
and that's what we call a stall if we
give the front wing on the canard a
slightly higher angle of incidence then
the front wing stalls first that drops
the nose down
and the main wing keeps flying and that
results in a stall resistant plane
let's see this in action look at that
the stall resistance that's actually
working
ah but here's the problem way too much
drag all those layers we added to the
front of the plane to make that little
wing happen
really causing the performance to suffer
here so we're gonna have to get creative
maybe even out of this world
next level
[Music]
this is the tube plane no wings it
rotates around a center of gravity that
isn't touching the plane and it gets its
lift
from spinning what is this sorcery the
folding on this paper airplane is
entirely different from anything you've
ever folded before but it's actually
really simple you're going to start by
folding a third of the paper over
and then you're going to fold that
layered part in half a couple of times
you're going to scrub that over the edge
of a table to bend it into a ring
and bada bing you've got a tube now
because this plane is circular and it
spins as it's flying
we're going to generate lift in a whole
new way using something called
a boundary layer let's see how a
boundary layer works
on another spinning object how do
boundary layer effects work
when enough air gets stuck to the
surface of the ball as the ball is
spinning it'll start to interact with
the other air
traveling past the ball and the net
effect is with some backspin
the ball will rise instead of going down
and that's boundary layer everything in
motion has a boundary layer
it's the microscopic layer of air that
travels with the surface of a moving
object
so when air is moving across a spinning
surface air on top of the ball is
additive
and air on the bottom cancels out
allowing the air on top to wrap around
and
exit in a downward stream that's newton
again this is how baseballs curve
golf ball soar tennis ball slice and how
ufos traverse the galaxy
i i made that last one up that's going
to be a whole other chapter on advanced
propulsion
and warp drive something really
interesting happens to wings when you
make them smaller and smaller let's
go really small something the size of a
dust speck
it just floats right there in the air it
doesn't have enough inertia to even
elbow air molecules aside so the closer
you get to the size of an air molecule
the more difficult it is to shove them
aside and make your way through
there's a number for that idea it's
called a reynolds number
and a reynolds number just measures kind
of the size of a wing compared to the
substance that the wing is traveling
through
a reynolds number helps scientists
predict flow patterns in any given fluid
system
and flow patterns can be laminar or they
can be turbulent
laminar flow is associated with low
reynolds numbers and turbulent flow is
associated with higher reynolds numbers
mathematically a reynolds number is the
ratio of the inertial forces in the
fluid
to the viscous forces in the fluid in
other words for a honeybee flying
through the air
it's much more like a person trying to
swim through honey
so ironically in this case there's a lot
happening on the surface level now the
tube
may not get us the distance that we want
but it does give us a real
insight to what's happening really close
up right down there at the surface level
of a paper airplane
so to recap the classic dart and the
super canard big drag issues
the phoenix and the tube good lift but
they really couldn't hold up for a long
throw
we've gone through all of this
incredible aerodynamic knowledge but the
problem still remains
how do we build all of that into a
simple piece of paper
so that it becomes an incredible paper
glider capable of
real distance let's level up again
this is suzanne and let's take a look at
how this thing
can really soar it can hold up on a hard
throw
it's slippery through the air and really
optimizes lift to drag in a way that
none of the other airplanes could this
is a surprisingly easy plane to fold
just a few simple folds but the key here
is to really make the creases
flush and precise the adjustment of the
wings is also critical
dihedral angle here becomes really
important
so taking into account everything we
talked about let's look at how this
design
actually flies reynolds numbers
tell us the airflow may shift from
turbulent at high speeds
to more laminar flow at slower speeds
at launch the flow is laminar only at
the nose
because of the coanda effect as the
plane slows down the air starts sticking
farther and farther back on the wing
at slower speeds the plane needs more
dihedral to keep from wandering off
course
this plane has more dihedral in the
middle of the wing where coanda effect
and reynolds numbers have worked
together to create
smooth airflow the center of gravity is
forward the up
elevator lifts the nose and now the
glide ratio kicks in
this paper airplane has flown past the
record distance by gliding
over the finish line instead of crashing
into it
[Applause]
empirical evidence has shown us exactly
how fluid behaves in an enclosed
environment
similar patterns that reveal themselves
on a small scale become even more
obvious on larger scale
and as we zoom farther out we can see
how atmospheric forces
gravitational forces even the surface of
the earth itself come into play
and once we reach a deeper understanding
of what we're seeing
that will allow us to unlock not just
better airplanes
but potentially a way to build more
accurate tools for predicting weather
a way to build better wind farms
everywhere that fluid dynamics touches
technology there's an opportunity
to make things more efficient for a
greener brighter future
and that's all the science behind
folding five paper airplanes
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