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Is It a Bird?
Bird-watching inspires a glider that soars almost as well as the real thing.
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We're here to do some
bird-watching-- once we spot
the bird. MAN: It's hanging
underneath the fuselage. It's
black-- you'll see it when it
gets airborne.
ALDA: Oh, I see it, yeah.
ALDA: The bird is actually a
glider, built by this man,
Bob Hoey. Watching with me is
Paul MacCready who's been
encouraging Bob in his quest
to design
a glider that can soar as
well as a real bird. To
MacCready's delight, Bob
seems to have done it.
MacCREADY: That's a real
bird. It really does look
real. ALDA:
Paul MacCready has been
watching birds for most of
his 75 years. Much of the
next hour will be kept in his
company as we explore some of
the extraordinary
accomplishments of a man
whose childhood passion for
all things that fly
has never left him. ALDA:
Paul, why do you do this?
What do you learn from this?
Well, first of all I think
everybody is interested in
birds.
And when you're four years
old and ten years old and 12
years old you like to watch
birds, wish you could be up
there with them. Look, look
how close he is! ALDA:
In those boyhood days, the
closest Paul could come to
being up there with the birds
was by building model
airplanes. His father
encouraged him, but never
instructed him. Paul
experimented with planes of
all kinds
setting records and winning
prizes. Meanwhile his
fascination with birds
expanded to include other
flying creatures. MacCREADY:
Nature has shown the great
value of flight.
For instance, if you're a
mouse crawling around through
the woods at night you maybe
can cover a quarter of an
acre and you're crawling up
and down through the muck and
swamp
and risking your life with
snakes and scorpions and so
on whereas a mouse with
wings, the same size, called
a bat can cover maybe 2,000
square miles that same night
safely up above all the
ground.
And it makes flight seem
pretty appealing. So it kind
of shows us that we humans
who are docilely walking
around on two-dimensional
flat ground all the time
might do a lot more going up
in the air
and get some of those
benefits that birds get.
ALDA: MacCready himself
joined the birds as a young
man when he became an avid
and highly competitive
sailplane pilot.
He was U.S. national soaring
champion three times and in
1956 he became the first
American to win the
international soaring
championship. Today he's
invited us to watch Bob
Hoey's bird glider with him
because it so perfectly
captures the philosophy that
has guided MacCready for the
last half century. MacCREADY:
Humans are part of nature and
we can learn an awful lot
about our technological
flying devices
by looking at nature, first
as a role model and then as
something to show how to
solve some of the big
problems. ALDA: The problem
Bob Hoey set out to solve
was how to get his glider to
turn. The thing that's
different about these
ailerons and the normal
ailerons is that they...
ALDA: Watching real soaring
birds, he suspected
they somehow employ the
feathers on the tips of their
wings. We've learned if we
put those things down like
that we will get a... a
little bit of forward thrust
out of these feathers,
actually.
What does that enable the
bird to do? It enables him to
turn. You see, if we put one
of them up and one of them
down
then it's like an aileron.
MacCREADY: When he gets lift
on this wing he also gets a
little thrust. ALDA: The
thrust pushes the wing
forward so that the bird can
turn as it banks
with little or no help from
the bird's tail. MacCREADY:
This works, and it took
nature 200 million years to
do it. It took Bob about...
two years? HOEY: About a
year.
One year, yeah. ALDA:
Inspiration from nature,
insight from theory and lots
and lots of experimentation
to make something fly that's
unlike anything that's ever
flown before-- that's the
MacCready credo.
Oh, and one more thing. That
bird looked like it was
having fun. ALDA: For Paul
MacCready, the fun really
began in the mid-1970s. A
British businessman, Henry
Kremer
was offering a large cash
prize to the builder of the
first successful
human-powered airplane and
MacCready had just taken on a
$100,000 debt for a friend.
MacCREADY: I had no interest
in human-powered flight
but I had heard of the Kremer
Prize. I knew it was £50,000,
and when I noticed in the
newspaper that at that
moment, a pound was exactly
two dollars suddenly this
light glowed:
"Why, that's the amount of my
debt! How exciting human-
powered airplanes are.
" And so... and seriously if I
hadn't had that debt there
wouldn't have been a Gossamer
Condor project. And when I
give talks, I tell people I
strongly recommend they
acquire a $100,000 debt to
get motivated
and they say many of them
have. ALDA: The debt may have
been the motive but it was
MacCready's love of watching
birds that put the Kremer
Prize within his grasp.
He was on a vacation trip
with his three young sons.
MacCREADY: We began really
studying different kinds of
birds because it turns out if
you time how long it takes to
do a circle
and you estimate the bank
angle you can immediately
calculate with a simple
formula how fast the bird is
flying and the size of the
turning radius. And how does
that compare with a hang
glider?
How does that compare with a
sailplane? It provided some
insight about the scaling
laws that suddenly made you
realize that the
human-powered airplane that I
was trying to think about
became feasible.
And if you just simply take a
hang glider and make it three
times as big wingspan but
keep the weight the same it
cuts the power down to one
third and that's down to what
a human can put out.
And suddenly that was the
idea for the Gossamer Condor
which wouldn't have arisen if
these birds hadn't been
circling around and us making
measurements.
Did you know when you started
watching the birds and
measuring their circles that
that was going to lead to a
human-powered plane?
MacCREADY: No, it was just a
fun thing to do
to keep the kids quiet on a
vacation trip. They kept
reciting Monty Python skits
state after state till you
were going out of your mind.
And then you started...
"Oh, let's measure birds now!
" ALDA: "Large and light" was
the lesson from the birds.
Paul also realized he could
even sacrifice strength for
lightness knowing that the
plane's low speed and
altitude meant
that even a crash would be
relatively harmless. Then in
September 1977, just two
years after being inspired by
the circling birds Paul
MacCready and his Gossamer
Condor
won the Kremer Prize. His
debt was paid off and a new
kind of flying was born. Dawn
in California's Mojave
Desert. Almost 20 years after
the Gossamer Condor flew into
history
Taking to the Air
What good is half a wing? Penn State scientists study the evolution of insect flight.
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One of the world's great
students of insect flight is
George Ruppel. Among his
favorite subjects:
dragonflies. RUPPEL: Here we
have caught a large dragonfly
one of the best fliers we
have. ALDA: And dragonflies
not only have powerful
wings... RUPPEL: Always it
will bite me. Ow! ALDA: We
met George Ruppel a few years
ago in Germany
where this marsh is one of
his favorite spots for
stalking dragonflies. How do
you look for them? Do... do
you scan with your eyes or do
you... Yes, I scan with my
eyes and then I detect
little... the blue and black
bodies. ALDA: Like most
scientists who study flying
creatures Ruppel employs
slow-motion photography. But
George shoots his movies on
location
rather than in the
laboratory. So, what's the
idea? Why come out to the
pond and shoot? Why don't you
take the dragonflies into the
laboratory
where the conditions are
controlled? Yes, controlled
but the dragonfly don't
behave normally. They only
show here in natural
conditions their full
behavior and even their full
flight behavior.
And, therefore, we have to go
out. Please let... have a
look. There is a dragonfly
sitting on the stem. I can...
I hope I can film it. ALDA:
What fascinates George Ruppel
about dragonflies
is how they use their flying
skills in their everyday
life. For example, male and
female dragonflies often fly
in tandem pairs after they
mate. The female has to dip
her tail into the water
to lay the eggs the male has
fertilized. By riding shotgun
like this the male is keeping
his rivals at bay. Here, one
of those rivals switches from
hovering flight to full
forward thrust
in an attempt to dislodge the
first male from his mate. A
third male briefly joins the
dogfight and in the
confusion, the first male
gets dunked. The attacker
switches to high-power
backward flight
as he pulls away with the
female. The aerobatics
continue as the new male
flips the female into a
somersault apparently
expelling the eggs the first
male fertilized. Now the
newcomer has a chance for
fatherhood.
Breaking free of both land
and water some 350 million
years ago flying insects
became the most successful
life-form on the planet.
Flying insects make up 60% of
all living species known to
science
even if their flying skills
sometimes fail them. But how
insects came to fly is one of
the great mysteries of
evolution. Where did wings
and all the complex muscles
and nerves needed to operate
them
come from? As the woods and
rivers of eastern
Pennsylvania began waking up
from their winter deep freeze
we joined biology professor
Jim Marden and his student
Melissa Kramer
in a hunt for clues to the
origins of insect flight. One
of these clues lies beneath
the water where many insects
begin life as swimming larvae
like this mayfly. MARDEN:
Have you seen him before?
KRAMER: No. ALDA: Its gills
beat in the water like
miniature oars and many
biologists now see these
flapping gills as the
forerunners of flapping
wings.
But that still leaves the
thorny question of just how
oars became wings. If
evolution proceeds in steps
with every step being useful
for something what use is
something halfway between an
oar and a wing?
It's a question Jim Marden
now believes he may have
answered thanks to his love
of fly-fishing. MARDEN: Well,
in fly-fishing you're tying
some feathers and string on a
hook
in order to imitate an
insect. But that's only half
the battle because then you
have to come out here in the
stream and present it to the
fish in the right way. And so
fly-fishing made me a real
student
of the behavior of insects on
water. ALDA: And it was while
watching insects on water--
especially a group of winged
but flightless insects called
stone flies--
that Jim Marden suddenly saw
what good a half wing could
be. Stone flies often emerge
from their larval form in the
middle of a river and they
need to get to shore quickly
in order to find a mate.
Stone flies are drab and
uninteresting even to most
biologists unless you're
planning an experiment to
find out if wings evolved
first not to fly in the air
but to skim across the
surface of the water.
Okay, let's see if we can get
one. ALDA: Back in the lab
the Pennsylvania State
University biologists found
their stone flies to be
highly cooperative
behaving in front of a
high-speed video camera just
as they do in the river.
Okay. MARDEN: Here she is and
we've just dropped her in the
water.
She's struggling to get free
of the surface tension. Here
she's raising up and trying
to get her tip of her abdomen
pulled off the water there.
The trick to this surface
skimming is, we've found
they have to really get up on
top of the water. It doesn't
work if any of them is
touching the water except
their tips of their legs.
There, now she's ready and
off she goes.
And she's nice and stable and
off screen flapping. You
still see her flapping into
the shadow. There she goes.
ALDA: This use of wings to
propel an insect across the
surface of water
is what Jim Marden believes
to be the missing link in the
evolution of flight. Most of
the experiments to test this
hypothesis were run by
Melissa Kramer. What I'm
doing is videotaping these
stone flies
surface-skimming from above
with a centimeter grid
underneath so that I can get
their velocity. I can measure
the time that it takes them
to run a certain distance by
getting that off of the
videotape.
ALDA: With the slow-motion
replay Melissa can count the
number of video frames it
takes for the stone fly to
skim a certain distance. The
insects average about 1½ feet
per second.
Then she clips the insect's
wings with a pair of nail
scissors and measures the
speed again. The insects are
slower, but not by much. Now
here's the critical test.
When she clips the wings to
mere nubs--
less than a quarter of their
original length-- the stone
flies can still use them to
skim around on the surface of
the water. So even a nub of a
wing-- a wing much too short
to allow flight--
can be useful, and completes
an evolutionary pathway along
which gills could have become
oars; oars, flapping sails;
and flapping sails, wings.
MARDEN: Well, the Darwinian
idea of evolution
is a gradual, stepwise
process. And so, right from
the time that Darwin first
proposed his ideas he was
attacked on many fronts. One
front was how do you get
highly complex traits that
only work in their full-
blown and fully integrated
form?
"What good is a nub of a
wing?
" is a direct quote from one
of Darwin's contemporaries.
So one of the things we're
out here doing with these
stone flies is showing what
nubs of wings really are used
for. ALDA:
Flapping Wings
Engineers look to nature's flapping wings to design an indoor flying machine.
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Most of the airplanes Paul
MacCready has made in his
life owe little to insects.
But not all. Is this going to
flap its wings? It will flap
and fly beautifully
unless I bust it while
assembling it. How many hours
did it take to build this?
Well, there's... a friend
builds these and he lets me
have them because he knows
I'm going to show them to
kids
and to people that think like
kids. But I need somebody to
wind, let's see, 20 turns. (
crank grinding ) It's flying
a little too straight now. (
dog barking in background )
( Alda laughs ) So you might
be able to get that to come
back to you? Oh, once it's
going right, it goes around
in circles that are about...
only about eight feet in
diameter.
You can practically fly it in
a phone booth. Do you ever
expect that a... that a plane
that will be used for
something will fly this way,
by flapping? Or is this...
The passengers in the 747
would really be irritated if
the wings went like that. (
laughing ) But it's virtually
identical to things that I
was making in 1939, 1940 and
if I hadn't been doing these
things then as a hobby
that led to other things
there wouldn't have been a
Gossamer Condor or the
247-foot airplane. So is it
practical as a device? No,
it's just fun. But as a
catalyst for thinking and
hands-on work
and developments and invention
it turned out to be hugely
valuable. The ones I made
were just about like this but
I also made some smaller ones
that had much more power and
would make noise like (
imitating engine )
and you release one behind
your teenage sister without
her knowing-- it just sounds
like a bat and it would
terrify her and little boys
like to do things like that.
Well, that sounds useful.
Yeah, it has its merits. (
Alda laughing ) ALDA: For
Paul, flapping wings may once
have been more entertaining
than practical. Crank it
another three or four, what
the heck.
ALDA: But as we'll see in a
moment there are plenty of
missions beyond scaring a
teenage sibling that a tiny
flapping flier could perhaps
one day take on. Now, we'll
see if this gets a turn.
Okay. Yeah, that's a little
more like it. Of course, if a
thermal comes that's the last
this will ever be seen. Of
course, if it lands in the
bush
it may be the last it's ever
seen, too. It doesn't get
hurt. ALDA: It's pollinating
the flowers! MacCREADY: For
some reason or other, kids
like this
CEOs of billion-dollar
corporations like it-- they
all want one. And cthe fact
that they can't have one
makes it more appealing to
them. ALDA:
One multibillion-dollar
organization that wants a
tiny flapping flier is the
Defense Department. For
soldiers fighting in
house-to-house combat a robot
able to scout ahead and peer
into rooms
could be a lifesaver. Wheeled
or tracked robots are already
being developed that can
carry cameras and other
sensors into dangerous
environments. But a small
flying robot would be faster,
more versatile
and harder to defeat. The
same defense agency
sponsoring the Black Widow we
saw earlier is also
supporting the development of
indoor fliers including one
at Georgia Tech. MAN:
If you're flying in close
quarters you've got to be
able to fly slow. If we made
this same vehicle with a
fixed wing it would have to
fly very fast and we'd have
difficulty landing and taking
off again.
Open rotors present a
problem, because if you touch
anything the rotor will
literally explode. But a
flapping wing is a very
robust device. Most people
have seen a beetle or a bird
that may have gotten into
their home and even though
they may bounce off the walls
they get up again, shake it
off and take off. ALDA: This
simple windup model has the
twin flapping wings
of the machine Rob Michelson
ultimately hopes to build.
That's the kind of leading
edge we should make. Yeah.
ALDA: But like others
tackling the same problem--
including Professor Yu-Chong
Tai at Caltech in Pasadena--
designers of flapping-wing
fliers face a difficult
problem. Making a windup
flapper, as Paul MacCready
proved almost 70 years ago,
is child's play.
But toys like this weigh
almost nothing. And even the
most miniaturized cameras,
sensors and computer
controls-- not to mention
motors and power supplies--
weigh something even if no
more than a key.
( wings clicking ) TAI: So we
may run into a dead end. That
means more weight, you
require more power but in
order to have more power, you
have to put more weight. And
there is an engineering
boundary where we can
achieve.
And that's where we're
exploring. ( wings clicking )
You have to design
more-efficient wings thNat
would generate a lift to
carry the weight. ALDA:
In their search for more
efficient wings the Caltech
researchers have linked up
with scientists at UCLA
hoping to learn the heavy
lifting secrets of insects.
MAN: This is a cicada wing
that I'm about to mount. It's
one of our larger insect
wings. It's also one of the
stiffest wings we have. ALDA:
The UCLA researchers have
been flapping
a variety of insect wings in
the wind tunnel. Strobe
lighting and smoke reveal the
way air flows around the
wings. The idea is to see how
insect wings generate lift
and then try to replicate
their key features in the
lab.
Actually making the wings
involves the latest in
high-tech manufacturing
methods. In the sort of
super-clean environment
usually used to make
microchips the wing design is
photographically transferred
to a thin sheet of titanium.
The pattern is then placed in
an acid bath to etch out the
wings' metal skeleton.
Finally, the skeleton is
covered with a thin plastic
film. When it came to making
the wings fly
the Caltech-UCLA engineers
turned to the experience of
Paul MacCready's
AeroVironment team--
specifically to Matt Keennon,
the builder of the Black
Widow. That looks fabulous.
What's the projected weight
for these wings
after they're cut out? Perhaps
about a few hundred
milligrams. ALDA: We joined
the group one day in 1999
when the insect-inspired wing
was undergoing flight
tests...
Why don't we test-fly this?
ALDA: And when it was quickly
obvious that insects still
know a thing or two that
aeronautical engineers don't.
Okay, ready? Three... two...
one... launch.
It's trying. We'd really like
to fly at the end of the
project about one minute. And
it should fly maybe a couple
hundred meters away. So
that's what we think we can
do.
But we still have about one
and a half years to go. And
this is a very exciting
project. We see it can fly
now. ALDA: Almost but not
quite flying is another entry
in the flapping wing derby
built by a team at SRI
International at Palo Alto.
They, too, know that somehow
they've got to find an extra
source of lift. MAN: In order
to achieve that extra lift
we've employed an aerodynamic
effect called "clap-fling"
which is used by insects and
birds of various sizes. ALDA:
In the slow-motion effect
produced by a strobe light
the wings can be seen folding
together and peeling apart.
MAN: As they come together...
they're twisting. And as they
come together quite closely,
they actually touch and they
squish the air out... down
which... which helps in... in
lift generation.
And then as they come apart,
they peel and this effect is
called "clap-fling" or
"clap-peel.
" And when they peel apart,
you're creating a vacuum in
here which forces the air to
suck in between the wings and
that is very beneficial. You
get on the order of 1.
5 to two times the lift. ALDA:
The wings' complex motion may
be based on biology but the
gears and wheels and rods
that produce the motion
aren't. In nature, muscles
both generate and deliver the
power to fly
with no need for motors or
transmissions. So several
teams attempting to make
microfliers-- including the
SRI team-- are trying to
develop artificial muscles.
Most work by contracting or
expanding
when an electric current is
applied. These experimental
artificial muscles are still
too slow and weak to power a
working flying machine so
these flappers are strictly
for demonstration only
including a butterfly made
entirely from artificial
muscle. So far, it hasn't
left its perch. Meanwhile,
over at Paul MacCready's
AeroVironment Matt Keennon
has replaced the
insect-inspired wings
that looked so promising 18
months ago in favor of wings
that look uncannily like the
ones his boss used to make 65
years ago. KEENNON: Three...
two... one... ALDA:
It may seem unlikely that the
MacCready philosophy of
testing and tweaking, testing
and tweaking 0÷ will ever
produce a machine that can
fly like a bird but that's
what they said about a plane
powered by a person.
Walkalong Glider
A model airplane unlike any other, designed by the son of inventor Paul MacCready.
Select text to jump ahead in the clip:
He's got it! He's got it! It's
on his head! ALDA: We're
going to end our visit with
Paul MacCready's flying
circus by meeting his son
Tyler who, with his two
brothers, helped build the
Gossamer Condor
25 years ago. We could chase
it like this for hours. ALDA:
When they got bored with
their father's project they
invented an extraordinary
little plane of their own.
And I can control it by
putting the lift on one side
of the wing or on the other.
ALDA: They called it their
"walkalong glider.
" I've never seen anything
like that. How old were you
when you invented that? Oh...
ten, 11, 12, something like
that. That's amazing. You've
got to teach me how to do it.
Let me see if I can do it.
So, what you need to do is
you need to be moving at a
walking speed before you let
go of it so that basically...
you don't throw it. You just
let go
of it and it's already
flying. Excuse me. The launch
is the most difficult part.
ALDA: Well, it may be the
part right after the launch