0:00 hi i'm john collins origami enthusiast
0:02 and world record holder for the farthest
0:04 flying
0:05 paper airplane
0:06 [Applause]
0:09 today i'm going to walk you through all
0:11 the science behind five
0:12 stellar paper airplanes most of us know
0:15 how to fold
0:16 a simple paper airplane but how is this
0:18 flying toy connected to smarter car
0:20 design
0:20 golf balls or clean energy by unlocking
0:23 the principles of flight
0:25 and aerodynamics we could affect the
0:27 world on a massive scale
0:28 and by the end of this video you're
0:30 gonna see paper airplanes
0:32 on a whole different level
0:33 [Music]
0:39 so to understand how this flies we're
0:41 gonna have to go back
0:42 and look at this the classic dart
0:51 i'm going to walk you through the
0:52 folding on this really simple paper
0:54 airplane
0:54 the classic dart is just a few simple
0:56 folds done well
0:58 sharp creases are the key to any paper
1:00 airplane there's not a lot of
1:01 aerodynamics here so it's really just
1:03 about getting some folds accurate
1:04 too little adjustments are going to help
1:06 this plane or any paper airplane fly
1:08 better
1:08 positive dihedral angle and just a
1:10 little bit of up elevator
1:12 there are two key adjustments that will
1:14 help any paper airplane fly better
1:16 the first one is called dihedral angle
1:18 and that's really just angling the wings
1:20 upward as they leave the body of the
1:21 plane that puts the lifting surface
1:24 up over where all the weight is so if
1:25 the plane rocks to one side it just
1:27 swings back to neutral
1:28 the other thing is up elevator just
1:30 bending the back of the wings
1:32 upward just a little bit at the tail so
1:34 air will reflect off of that
1:36 push the tail down which lifts the nose
1:38 those two things will keep your airplane
1:39 flying
1:40 great let's see how this plane flies to
1:43 demonstrate
1:44 our producer is testing it in an
1:45 enclosed environment
1:52 with the main forces acting on this
1:53 plane to fly this plane will travel only
1:56 about as far as your strength can muster
1:57 before gravity takes over but that's the
2:00 problem
2:00 there's too little lift and too much
2:03 drag on this plane the ratios are just
2:05 all off
2:06 drag is the sum of all the air molecules
2:09 resisting an
2:10 object in motion that's why windshields
2:13 are now raked way back on automobiles
2:15 that's why airplanes have a pointy nose
2:17 to reduce drag
2:18 you want to cut down on the amount of
2:20 drag so that it takes less energy
2:22 to move forward and with any flying
2:24 machine even our paper airplane
2:25 drag is one of the four main aerodynamic
2:28 forces
2:29 the others are of course thrust the
2:31 energy that pushes an
2:32 object forward gravity which is of
2:34 course the force that pulls everything
2:36 toward the earth
2:36 and lift that's the force that opposes
2:39 gravity
2:40 and when all four of those forces are
2:42 balanced you have flight
2:44 here's how all these forces are acting
2:47 on the plane
2:47 when the dart flies through the air it
2:49 uses its narrow wingspan
2:51 and long fuselage with the center of
2:53 gravity positioned near the center of
2:54 the plane
2:55 to slice through the air molecules it's
2:57 very sturdy and flies very straight
2:59 the problem is it can only fly about as
3:02 far as you can chuck it before gravity
3:04 takes over
3:04 but once you put some aerodynamic
3:06 principles to the test you can find
3:08 clever ways to make the plane go farther
3:10 what if we tucked in some of the layers
3:12 to eliminate some of the drag
3:13 and expanded the wings to provide a
3:15 little more lift so that the plane can
3:17 glide
3:18 across the finish line rather than crash
3:20 into it and explode
3:23 so what do we need to make this plane
3:25 fly better more lift of course
3:28 but what is lift exactly for a long time
3:31 the bernoulli principle was thought to
3:33 explain lift
3:34 it states that within an enclosed flow
3:36 of fluid points of higher fluid speeds
3:39 have less pressure than points of slower
3:41 fluid speeds
3:42 wings have a low pressure on top and
3:45 faster moving air on top so
3:46 bernoulli right wrong bernoulli works
3:50 within a pipe an enclosed environment
3:52 faster moving air in this case does not
3:54 cause low pressure atop the wing
3:56 so what does to understand that we're
3:59 going to have to take a really close
4:00 look at how air moves around an object
4:03 there's something called the coanda
4:04 effect which states that
4:06 airflow will follow the shape of
4:08 whatever it encounters
4:09 let's look at a simple demonstration of
4:11 these two things
4:13 okay two ping-pong balls right faster
4:15 moving air between them
4:16 check the ping-pong balls move together
4:19 must be a low pressure right
4:21 wrong that's where it gets confusing
4:25 so as the air moves between the
4:27 ping-pong balls it follows the shape of
4:29 the ping-pong balls and gets deflected
4:30 outward
4:32 that outward shove pushes the ping-pong
4:34 balls together
4:35 inward what we're talking about here is
4:38 newton's third law
4:40 equal and opposite reaction so it's not
4:43 bernoulli that causes the ping-pong
4:45 balls to move together
4:46 it's that air being vectored outward
4:48 shoving the ping-pong balls together
4:51 inward let's see how that works on a
4:53 real wing
4:54 notice how the airflow over the wing
4:56 ends up getting pushed
4:58 downward at the back of the wing that
5:00 downward shove
5:01 pushes the wing upward and that is lift
5:05 so if the narrow wings on this dart
5:08 aren't providing enough lift
5:09 and the body of the plane is providing
5:11 too much drag what can we do
5:13 well we'll need to design a plane with
5:15 bigger wings that slips through the air
5:17 easily let's take it to the next level
5:22 this is a plane i designed called the
5:24 phoenix lock just ten folds
5:26 it's called the phoenix lock because
5:27 there's a tiny locking flap that holds
5:29 all the layers together and that's gonna
5:31 get rid of one of the big problems we
5:33 saw with the dart where those layers are
5:34 flopping open in flight
5:36 now what you'll see here in the finished
5:38 design is that we've done two things
5:40 made the wings bigger and brought the
5:42 center of gravity forward a little more
5:45 making the lift area behind the center
5:46 of gravity bigger as well
5:48 it's a glider versus a dart normal
5:51 planes have propulsion systems like
5:52 engines that supply thrust
5:54 gliders on the other hand need to
5:56 engineer in a way to gain speed
5:58 and to do that you need to trade height
6:00 for speed
6:01 let's take a look at what's happening
6:03 with the new design with the center of
6:04 gravity
6:05 more forward on the plane this plane
6:07 will point nose down
6:08 allowing you to gain speed that's lost
6:11 from drag
6:12 and then when the plane gains enough
6:13 speed just enough air to flex off of
6:15 these tiny bins at the back of the plane
6:17 to push the tail down
6:19 which lifts the nose up and that's how
6:21 the plane achieves a balanced
6:23 glide what the bigger wing area does is
6:25 allow for better
6:26 wing loading now wing loading contrary
6:29 to popular belief
6:30 is not how many wings you can stuff in
6:31 your mouth before snot starts coming out
6:33 of your nose
6:35 no wing loading is really the weight of
6:37 the whole plane
6:38 divided by the lifting surface in this
6:40 case the wings of the plane not
6:42 not buffalo wings high wing loading
6:44 means the plane has to move much
6:46 faster to lift the weight low wing
6:49 loading means the plane can fly
6:50 slower to lift the weight since each
6:53 plane is made out of the same
6:54 paper the weight is constant the only
6:57 thing that's really changing here
6:58 is the size of the wings and that's
7:00 what's changing the wing loading
7:02 think about things in real life where
7:03 this applies look at a monarch butterfly
7:06 really lightweight design right it's an
7:08 insect doesn't weigh much and it's got
7:09 giant wings it just kind of floats
7:11 slowly through the air
7:12 and then look at a jet fighter really
7:15 fast
7:16 really small wings just made the slice
7:18 through the air at high speeds
7:20 that's really the difference in wing
7:22 loading here big wings
7:24 slow small wings fast now let's go one
7:27 step further and see how
7:28 wind loading can affect the distance in
7:30 flight watch what happens when the
7:32 phoenix flies
7:33 it just glides more in that distance
7:36 that it moves forward for every unit of
7:37 height that it drops
7:38 that's called glide ratio or lift to
7:41 drag ratio
7:43 applying this to planes in real life an
7:45 aircraft might have a glide ratio
7:47 of 9 to 1. that's roughly the glide
7:50 ratio of a cessna 172 so that means
7:52 if you're flying that cessna and your
7:54 engine quits at an altitude of 100
7:56 meters
7:57 there better be an airfield or a cow
7:58 pasture less than 900 meters away
8:01 or you'll be in real trouble modern
8:03 gliders can have a glide ratio as high
8:05 as
8:05 40 to 1 or even 70 to 1. hang gliders
8:08 have a glide ratio of around 16 to 1.
8:11 red bull flutaw gliders maybe have a
8:13 glide ratio of one to one but that's
8:16 really more dependent on the ratio of
8:18 red bull to red beers in their stomachs
8:20 when they were
8:20 designing their aircraft now we have a
8:23 plane with much bigger wings that slips
8:25 through the air
8:26 a lot better so we can use that thrust
8:28 to gain a lot of height
8:30 and then efficiently trade height for
8:32 speed that is
8:33 use all that thrust to get some altitude
8:35 and use that efficient glide ratio
8:37 to get some real distance but there's a
8:40 new problem
8:40 this plane just can't handle a hard
8:43 throw we're gonna need a good amount of
8:44 thrust to get it to go the distance
8:46 so if the dart held up to a strong throw
8:48 but had too much drag
8:50 and the phoenix did really well with a
8:52 soft throw but couldn't handle the speed
8:54 what we're gonna need is something
8:56 that's structurally sound that can
8:58 handle
8:58 all the thrust and still have a wing
9:00 design that will allow us to create
9:02 efficiency
9:03 that will go the distance let's level up
9:08 this is the super canard the folding on
9:11 this deliciously complex
9:13 squash folds reverse folds petal folds
9:15 really interesting folding
9:17 it requires a high degree of precision
9:19 accurate folding and
9:20 symmetry and what's special about it is
9:23 it's got two sets of wings a forward
9:25 wing and a rear wing
9:26 and that's going to make the plane stall
9:28 resistant we'll talk more about that in
9:30 a moment
9:30 we can see a few things here center of
9:32 gravity is in front of the center of
9:34 lift
9:34 check can it hold together with stronger
9:36 thrust yes
9:38 the winglets actually create effective
9:40 dihedral making the wingtip vertices
9:42 shed more cleanly
9:43 and control left right roll better
9:45 making it more stable in flight
9:47 wing loading well the interesting thing
9:49 is you can see the design of the dart
9:51 inside the canard and what it looks like
9:53 we've done is added more wing area to it
9:55 however the canard design is much
9:58 smaller than the dart so we're not
9:59 getting a big advantage here in terms of
10:01 wing loading
10:02 it's very sturdy so it can handle a lot
10:04 of thrust so we're hoping it can go the
10:06 distance but what's really cool about
10:08 this plane
10:08 is that it's stall resistant let's take
10:11 a look at what a stall
10:13 actually is on a wing a stall is caused
10:16 either by
10:17 too slow of an air speed or too high an
10:19 angle of incidence
10:21 remember the koanda effect the coanda
10:23 effect is the tendency of a fluid to
10:25 stay attached to a curved surface
10:27 when air travels over a wing it sticks
10:29 to the surface and
10:30 bending flow results in aerodynamic lift
10:32 but when a plane is traveling with too
10:34 high
10:34 an angle of incidence the air can't
10:36 adhere to the surface of the wing so
10:38 lift is lost
10:39 and that's what we call a stall if we
10:41 give the front wing on the canard a
10:43 slightly higher angle of incidence then
10:46 the front wing stalls first that drops
10:48 the nose down
10:49 and the main wing keeps flying and that
10:52 results in a stall resistant plane
10:54 let's see this in action look at that
10:57 the stall resistance that's actually
10:59 working
11:00 ah but here's the problem way too much
11:02 drag all those layers we added to the
11:04 front of the plane to make that little
11:05 wing happen
11:06 really causing the performance to suffer
11:08 here so we're gonna have to get creative
11:11 maybe even out of this world
11:14 next level
11:15 [Music]
11:18 this is the tube plane no wings it
11:21 rotates around a center of gravity that
11:22 isn't touching the plane and it gets its
11:24 lift
11:25 from spinning what is this sorcery the
11:28 folding on this paper airplane is
11:30 entirely different from anything you've
11:32 ever folded before but it's actually
11:33 really simple you're going to start by
11:35 folding a third of the paper over
11:36 and then you're going to fold that
11:38 layered part in half a couple of times
11:40 you're going to scrub that over the edge
11:41 of a table to bend it into a ring
11:43 and bada bing you've got a tube now
11:46 because this plane is circular and it
11:48 spins as it's flying
11:50 we're going to generate lift in a whole
11:51 new way using something called
11:53 a boundary layer let's see how a
11:56 boundary layer works
11:57 on another spinning object how do
11:59 boundary layer effects work
12:01 when enough air gets stuck to the
12:02 surface of the ball as the ball is
12:04 spinning it'll start to interact with
12:06 the other air
12:07 traveling past the ball and the net
12:09 effect is with some backspin
12:10 the ball will rise instead of going down
12:14 and that's boundary layer everything in
12:17 motion has a boundary layer
12:18 it's the microscopic layer of air that
12:20 travels with the surface of a moving
12:22 object
12:22 so when air is moving across a spinning
12:24 surface air on top of the ball is
12:26 additive
12:27 and air on the bottom cancels out
12:29 allowing the air on top to wrap around
12:31 and
12:31 exit in a downward stream that's newton
12:34 again this is how baseballs curve
12:36 golf ball soar tennis ball slice and how
12:39 ufos traverse the galaxy
12:42 i i made that last one up that's going
12:44 to be a whole other chapter on advanced
12:45 propulsion
12:46 and warp drive something really
12:48 interesting happens to wings when you
12:50 make them smaller and smaller let's
12:52 go really small something the size of a
12:54 dust speck
12:55 it just floats right there in the air it
12:57 doesn't have enough inertia to even
12:59 elbow air molecules aside so the closer
13:02 you get to the size of an air molecule
13:04 the more difficult it is to shove them
13:07 aside and make your way through
13:08 there's a number for that idea it's
13:10 called a reynolds number
13:12 and a reynolds number just measures kind
13:15 of the size of a wing compared to the
13:17 substance that the wing is traveling
13:18 through
13:19 a reynolds number helps scientists
13:20 predict flow patterns in any given fluid
13:22 system
13:23 and flow patterns can be laminar or they
13:25 can be turbulent
13:26 laminar flow is associated with low
13:28 reynolds numbers and turbulent flow is
13:30 associated with higher reynolds numbers
13:32 mathematically a reynolds number is the
13:34 ratio of the inertial forces in the
13:36 fluid
13:37 to the viscous forces in the fluid in
13:39 other words for a honeybee flying
13:41 through the air
13:42 it's much more like a person trying to
13:44 swim through honey
13:45 so ironically in this case there's a lot
13:48 happening on the surface level now the
13:50 tube
13:50 may not get us the distance that we want
13:52 but it does give us a real
13:54 insight to what's happening really close
13:57 up right down there at the surface level
13:58 of a paper airplane
14:00 so to recap the classic dart and the
14:02 super canard big drag issues
14:04 the phoenix and the tube good lift but
14:07 they really couldn't hold up for a long
14:09 throw
14:10 we've gone through all of this
14:11 incredible aerodynamic knowledge but the
14:13 problem still remains
14:14 how do we build all of that into a
14:17 simple piece of paper
14:19 so that it becomes an incredible paper
14:21 glider capable of
14:22 real distance let's level up again
14:27 this is suzanne and let's take a look at
14:30 how this thing
14:31 can really soar it can hold up on a hard
14:34 throw
14:34 it's slippery through the air and really
14:37 optimizes lift to drag in a way that
14:39 none of the other airplanes could this
14:41 is a surprisingly easy plane to fold
14:44 just a few simple folds but the key here
14:46 is to really make the creases
14:48 flush and precise the adjustment of the
14:50 wings is also critical
14:52 dihedral angle here becomes really
14:54 important
14:55 so taking into account everything we
14:57 talked about let's look at how this
14:59 design
14:59 actually flies reynolds numbers
15:03 tell us the airflow may shift from
15:05 turbulent at high speeds
15:06 to more laminar flow at slower speeds
15:10 at launch the flow is laminar only at
15:12 the nose
15:13 because of the coanda effect as the
15:15 plane slows down the air starts sticking
15:17 farther and farther back on the wing
15:19 at slower speeds the plane needs more
15:21 dihedral to keep from wandering off
15:24 course
15:24 this plane has more dihedral in the
15:26 middle of the wing where coanda effect
15:28 and reynolds numbers have worked
15:30 together to create
15:31 smooth airflow the center of gravity is
15:33 forward the up
15:34 elevator lifts the nose and now the
15:36 glide ratio kicks in
15:38 this paper airplane has flown past the
15:41 record distance by gliding
15:42 over the finish line instead of crashing
15:45 into it
15:46 [Applause]
15:48 empirical evidence has shown us exactly
15:50 how fluid behaves in an enclosed
15:52 environment
15:53 similar patterns that reveal themselves
15:55 on a small scale become even more
15:57 obvious on larger scale
15:58 and as we zoom farther out we can see
16:00 how atmospheric forces
16:02 gravitational forces even the surface of
16:04 the earth itself come into play
16:06 and once we reach a deeper understanding
16:08 of what we're seeing
16:09 that will allow us to unlock not just
16:11 better airplanes
16:13 but potentially a way to build more
16:15 accurate tools for predicting weather
16:17 a way to build better wind farms
16:19 everywhere that fluid dynamics touches
16:20 technology there's an opportunity
16:22 to make things more efficient for a
16:24 greener brighter future
16:26 and that's all the science behind
16:28 folding five paper airplanes
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