Airdate: April 10, 2001
IS IT A BIRD?
THE ETERNAL WING
EYES IN THE SKY
TO THE AIR
ALAN ALDA My eyes are about to take to the air while
the rest of me stays firmly on the ground. I'm very
PAUL MACCREADY That makes two of us.
ALAN ALDA (NARRATION) We're joining a legendary engineer
inspired by nature.
PAUL MACCREADY That bird looks like
it was having fun.
ALAN ALDA (NARRATION) A quarter century after he built
the first human powered plane, Paul MacCready's creations
are still revolutionary… and are themselves inspiring
a new generation of flying machines… including a plane
that may one day fly on Mars.
ALAN ALDA I'm Alan Alda. Join me as Scientific American
Frontiers enjoys the pleasures of Flying Free.
IS IT A BIRD?
ALAN ALDA (NARRATION) We're here to do some bird watching
-- once we spot the bird.
BOB HOEY It's hanging underneath
the fuselage. It's black. You'll see it when it gets
ALAN ALDA Oh, I see it, yeah.
ALAN ALDA (NARRATION)
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.
PAUL MACCREADY That's a real
ALAN ALDA It really does look real, you're right.
ALAN ALDA (NARRATION) 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.
ALAN ALDA Paul, why do you do this? What do you learn
PAUL MACCREADY Well, first of all, I think
everybody is interested in birds. And when you're four
years old and ten years old and twelve years old you
like to watch birds, wish you could be up there, with
ALAN ALDA Look, look how close he is, look at
ALAN ALDA (NARRATION) In those boyhood days, the
closest Paul could come to being up there with the birds
was by building model airplanes. His father encouraged
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.
PAUL MACCREADY Nature has shown
us the great value of flight. For instance, if you're
a mouse crawling around through woods at night, you
can maybe cover quarter of an acre and you're crawling
up and down through muck and swamp and risking you life
with snakes and scorpions and so on. Whereas a mouse
with wings, the same size, called a bat, can cover maybe
2000 square miles that same night, safely up above all
the ground. And it makes flight seem pretty appealing…
So it kinds 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 birds get.
ALAN ALDA (NARRATION)
MacCready himself joined the birds as a young man, when
he became an avid -- and highly competitive -- sailplane
pilot. He was US 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.
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.
ALAN ALDA (NARRATION) The problem Bob Hoey set out to solve
was how to get his glider to turn.
BOB HOEY The thing
that's different about these ailerons and normal ailerons
is that they…
ALAN ALDA (NARRATION) Watching real soaring
birds, he suspected they somehow employ the feathers
on the tips of their wings.
BOB HOEY Now we've learned
if we will get a little bit of forward thrust out of
these feathers, actually.
ALAN ALDA What does that enable
the bird to do?
BOB HOEY 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.
PAUL MACCREADY When it gets lift
on this wing he also gets a little thrust.
(NARRATION) 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.
PAUL MACCREADY This works. And
it took nature 200 million years to do it. And it took
Bob about two years?
BOB HOEY About one year.
One year, yeah.
ALAN ALDA (NARRATION) 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…
PAUL MACCREADY That bird looked
like it was having fun.
ALAN ALDA (NARRATION) 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.
PAUL MACCREADY I had no interest
in human powered flight, but I had heard of the Kremer
Prize and I knew it was 50,000 pounds, and when I noticed
in the newspaper that at that moment the pound was exactly
two dollars, suddenly this light glowed -- why that's
the amount of my debt, how exciting human powered airplanes
are… 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 many of
them say they have.
ALAN ALDA (NARRATION) 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
PAUL 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 that compares with a hang glider, how
does that compare with a sailplane, it provided some
insight about 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 the wing
span 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.
ALAN ALDA Did you know when you started watching the birds
and measuring their circles that that was going to lead
to a human powered airplane?
PAUL 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.
You started…let's measure birds now!
ALAN ALDA (NARRATION)
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.
THE ETERNAL WING
ALAN ALDA (NARRATION) Dawn in California's Mojave
Desert. Almost 20 years after the Gossamer Condor flew
into history, its direct descendent is being rolled
out for another historic flight. The Pathfinder is a
flying wing, powered by the sun. Built by Paul MacCready's
company, Aerovironment, the Pathfinder has been prepared
for this moment by project manager Bob Curtin.
ALAN ALDA It's very long. How long is this wing?
That's a hundred-foot wing span.
ALAN ALDA A hundred
feet, and it's all wing, right?
BOB CURTIN That's right.
It's all wing, there's no surfaces in back like a normal
ALAN ALDA Why did you make it all wing?
BOB CURTIN Well it's the optimum shape for something that
you need to, to make very light, and collect a lot of
solar energy. It happens to be a wing.
ALAN ALDA (NARRATION)
Every inch of the wing is covered with wafer-thin solar
cells. Even so, there's not exactly power to spare.
ALAN ALDA How much energy are these solar cells collecting?
BOB CURTIN They'll collect at noon about 6,000 watts,
which is about four hair dryers' worth of energy.
ALAN ALDA C'mon. Now wait a minute, wait a minute. You fly
this 100-foot long wing with the energy that it takes
to run four hair dryers?
BOB CURTIN Exactly, four hair
ALAN ALDA (NARRATION) There's also a small reserve
of battery power.
ALAN ALDA Is that how you keep it
closed when it's in flight or do you --
BOB CURTIN Well,
there will be more tape. There's, there will be tape
ALAN ALDA More tape...
BOB CURTIN That's right,
more tape. But you're right, I mean, there is a lot
of tape on this airplane.
ALAN ALDA This is the battery?
BOB CURTIN This is the battery pack, it's, it weighs
about 40 pounds, and it'll power the airplane for about
three or four hours.
ALAN ALDA (NARRATION) Like the
Gossamer Condor, the wing owes a debt to MacCready's
model building youth.
ALAN ALDA When you look through
this transparent material here, it's almost like looking
at a model airplane.
BOB CURTIN That's right.
There's little struts like something like what I used
to carve out of balsa wood when I was a kid.
It's very similar to a model airplane. The ribs that
form the wing shape that are made out of Styrofoam.
They're made out of balsa wood in model airplanes, but
ALAN ALDA (NARRATION) Hollow Kevlar propellers
are driven by high-tech electric motors. Each streamlined
cone weighs less than one ounce. The entire plane, with
six motors, the battery pack and sixty pounds of solar
cells weighs under five hundred pounds. The wing is
so large and so light that even taking it out of its
hanger is a tricky operation. The team has to keep a
constant eye on the wind. The fear is that a sudden
gust could snatch the wing into the air.
We have a bit of a tail wind right now, so I think we
should rotate the airplane around about 180 degrees.
ALAN ALDA (NARRATION) Up until this day in 1995, the
Pathfinder had so far flown only at a thousand feet
or so. Now the team is preparing for the first high-altitude
flight. The motors are now running on the sunlight falling
on the wing. Yet it's so light, the engineers have to
hold it back. It'll take off, either from the blowing
wind or the movement of the plane, at just nineteen
miles an hour. Using the sun to power a plane is the
sort of outrageous idea that once only a mind like Paul
MacCready's could take seriously. But his first such
plane, a hybrid running on both human and solar power,
successfully crossed the English Channel in the early
1980s. It was a typical MacCready stunt. But by September
1995, the potential of a solar-powered plane had become
so great that NASA was paying the bills as the wing
was being prepared for its first high altitude flight.
BOB CURTIN We're going to try to fly the airplane as
high as it can, as high as it can fly, basically. And
as long as weather holds - right now the weather isn't
looking very good.
ALAN ALDA (NARRATION) On this day,
the winds became dangerously high for the fragile plane.
For several days the team rolled the wing out to the
lakebed at dawn…
BOB CURTIN So the wind is blowing at
about 7 miles an hour; we're at our limit. We don't
want it to get much higher than this.
ALAN ALDA (NARRATION) And then they rolled it back
to the hanger to wait for the next morning. Finally,
with winds no more than five miles an hour, the first
high-altitude flight was ready for launch. Of course
the wing had no pilot, so it was to be flown remotely
from the ground. Takeoff was handled from a nearby chase
PILOT Everybody ready?
CO-PILOT I'm ready.
BOB CURTIN I'm ready.
PILOT -- Looks good, go for a throttle up.
PILOT Four and five, on...
ALAN ALDA (NARRATION) At full power in the morning sun, the
wing accelerated across the lakebed. The nineteen mile-an-hour
lift-off speed was reached within seconds. PILOTS Main's
lifting off. Nose wheel's lifting off. Ten feet. Airspeed's
27. 60 feet. Airspeed hold on at 27. 30 feet per second.
BOB CURTIN Maybe around 600 feet, 5-600 feet right now.
It was a good climb out.
ALAN ALDA (NARRATION) As the wing gently spiraled up
from the desert floor, it was followed with cameras
more used to observing the space shuttle. And that's
appropriate, because MacCready's idea is that solar
wings, circling at high altitude, can replace many space
PILOT I wonder if we'll ever see it again.
BOB CURTIN I hope so.
ALAN ALDA (NARRATION) On this flight, the crew's aim was
to see how high they could push the Pathfinder.
BOB CURTIN We're at 33,000 feet, things are going well.
No serious problems right now. In fact we don't have
any problems right now.
ALAN ALDA (NARRATION) They worked
from a control room in an old army truck.
BOB CURTIN Now select waypoint 98.
PILOT OK. Waypoint 98.
We are heading towards a high wind area at 40,000 feet.
ALAN ALDA (NARRATION) Now came a big hurdle. The wing
had never before flown through the strong winds of the
jet stream. But the on-board camera showed the flexible
structure riding the turbulence beautifully.
PILOT We're going to increase the speed a little bit
because we're not doing so well in the climb.
ALAN ALDA (NARRATION)
By late afternoon it was clear that because of greater
than expected winds they wouldn't make their sixty-five-thousand-feet
goal. But it was still a flight that broke the altitude
record for solar-powered planes by an enormous forty
BOB CURTIN The sun is going down now.
We still have a climb rate so we're climbing. But at
some point the sun's going to get low enough that our
climb rate goes to zero. And, and when the climb rate
goes to zero, we'll be at our maximum altitude. PILOT
There it is, five zero zero zero zero.
BOB CURTIN This
is an extraordinary flight; now we've just got to get
ALAN ALDA (NARRATION) They switch to the onboard
batteries to bring the plane back in the darkness. Two
hours after sunset, and the Pathfinder arrives home.
BOB CURTIN 300 feet. PILOT I guess we're higher than
that. PILOT OK, you want to slow down a little...
ALAN ALDA (NARRATION) This 1995 flight showed that a plane
powered by the sun could fly high above even the largest
and most powerful commercial jetliners. PILOT Beautiful,
that's the most beautiful thing I've seen in my life.
ALAN ALDA (NARRATION) But it was only the first step
toward Paul MacCready's vision of what his solar wing
could become. Five years later, in the fall of 2000,
the wing had more than doubled in length to almost 250
ft, while the number of motors had gone from six to
fourteen. Now called Helios, the giant flying wing was
undergoing low altitude tests for what is intended to
be a flight to 100,000 ft -- almost 19 miles high--
in the late spring of 2001.
ALAN ALDA This would fly
way above other aircraft. I mean, nobody's going to
bump into it because they're all below it. Do I have
PAUL MACCREADY That's pretty much right.
This one is slated to do just a demonstration stunt,
to see if we can do it, the challenge to get to 100,000
feet, where there's only about one percent as much air
density as there is on the ground. But mostly it's aimed
at flying at around 65,000 feet because the wind is
light enough there so it can stay in one place.
ALAN ALDA (NARRATION) And here we come to the reason why
the solar powered wing is much more than a stunt. Circling,
like MacCready's favorite birds, high above a city,
a flying wing could be an alternative to space satellites
for relaying voice or television or Internet signals.
Aerovironment's plan is for Helios to circle silently
on solar power for as long as six-months. Then one wing
would descend as another flies up to take its place.
ALAN ALDA So you would bring it down every six months
to make sure that it's in tiptop shape. Is that the
PAUL MACCREADY Yeah, I'm sure you'd have
to replace something. But also every six months you'd
probably have better communication gear to put in it.
One of the bad features of satellites is that you put
'em up with today's technology and to get them to be
economically viable you have to keep it up for say ten
years. In ten years, say the last five of these years,
your technology is old fashioned. So here you get a
chance to redo it every six months.
ALAN ALDA (NARRATION)
Since last fall, Aerovironment engineers have been laboriously
testing and applying to the giant wing sections the
solar cells that will power the Helios. Since the solar
panels will provide power only during daylight hours,
the team is also working on a system of fuel cells --
a kind of lightweight and highly efficient battery --
to store daytime electricity and keep the wing flying
during the night. In the low altitude flight tests last
fall, the Helios was still powered by conventional batteries.
But the plane performed flawlessly, experimenting with
using its motors to turn and even to pitch up and down.
If the method works, the control systems for the wing
could be greatly simplified -- another spectacular example
of the MacCready credo of more for less.
IN THE SKY
ALAN ALDA Now what have they got in those cases?
Well, that's a small surveillance airplane, kind of
a nine pound, nine foot, collapsible that we've been
making for over ten years now. They get pretty widely
used for being a pair of roving eyeglasses wherever
you want to see what's over the next hill.
(NARRATION) Paul MacCready's fascination with flying
began with model airplanes -- and now he makes them
for people who want the advantage of a bird's eye view.
Called the Pointer, the plane is a typically MacCreadian
combination of high and low tech.
ALAN ALDA So this
wing is held on only with rubber bands, huh? Why do
you do that?
PAUL MACCREADY So they'll pop off.
MARK LEVOE Yeah, it's a safety device. So that if it
lands really hard the wing will pop off and not cause
ALAN ALDA (NARRATION) The idea behind the Pointer
is that it can be taken anywhere and be launched and
flown by people with only minimal training.
How high is it now?
PAUL MACCREADY I'd imagine it's
about 250 feet and it's making a little more noise because
it's climbing. If it's just cruising along it can go
over your head at 50 feet and nobody even notices it
because you're not looking up all the time.
What is that structure down there that the plane is
PAUL TRIST That was a movie set for Eddie
Murphy's Coming to America and it's the remains of it.
ALAN ALDA So this is a perfect use for the plane. If
we were paparazzi now…
PAUL TRIST Correct, correct….
ALAN ALDA And we wanted to spy on Eddie Murphy's house…
PAUL TRIST Yeah, we could look in someone's backyard
and they probably wouldn't even know we were there.
ALAN ALDA You now it's great to know that scientific
progress is being made like this.
ALAN ALDA (NARRATION)
How's this for surreal: gazing down from the California
sky at the remains of Eddie Murphy's fictional African
ALAN ALDA Is that it? That's it, isn't
PAUL TRIST There it is there.
PAUL MACCREADY Yeah.
Alan, maybe we didn't mention it but you are going to
do the flying on the next flight, all of it.
You're not afraid of that?
PAUL MACCREADY No, though
we are making it the last flight of the day, just in
ALAN ALDA You know, I have to warn you that I
flew a jet in a simulator once, and I crashed it.
ALAN ALDA (NARRATION) I actually crashed the simulated jet
when I was trying to land it. At least I shouldn't have
that problem with the Pointer, which goes into an automatic
landing mode at the touch of a switch.
ALAN ALDA Oh,
wait a minute, whoa. I though you were going to hit
me with that plane. It looked like it was coming right
PAUL TRIST Yeah it was, but that's about…. We
could even get closer if we wanted to. It's just that
I didn't want to hit the cameraman.
ALAN ALDA Believe
me, that's the least of your worries.
PAUL TRIST OK,
we're going to go through a pre-flight check.
PAUL TRIST OK
ALAN ALDA I'm very nervous.
PAUL MACCREADY That makes two of us.
PAUL TRIST So the
only thing you have to worry about is that we have a
slight crosswind, and you'll probably have to give a
little bit of left rudder. So we'll give it full throttle…
ALAN ALDA Full throttle. All the way forward?
All the way forward OK.
ALAN ALDA (NARRATION) Here we
go. Now, it would be nice to claim that my belly flop
was a calculated test of the plane's durability…
ALAN ALDA Oy, it's going down again.
ALAN ALDA (NARRATION)
But the truth of course is that I need a little help.
ALAN ALDA It doesn't seem to want to go left.
You may have jarred something. It looks OK now.
ALAN ALDA (NARRATION) Looking down from above, it's easy
to get lost.
ALAN ALDA I can't tell where I am on the
PAUL TRIST Yeah, well you're coming across right
to left now.
ALAN ALDA OK, should I go left a bit more?
PAUL TRIST Yeah, why don't you do that. It's like steering
a bus. You've got to kind of anticipate and then let
ALAN ALDA OK, there's the structure. I'm going to
go right a little bit.
PAUL TRIST Right. So basically
you're just steering it. And you'll notice I'm giving
you very little input, you're just kind of flying it
ALAN ALDA Yeah
ALAN ALDA (NARRATION) Now all
I've got to do is land it.
PAUL TRIST Right about now.
Let's do it now.
ALAN ALDA Oh.
PAUL TRIST That's fine.
There you go.
ALAN ALDA Well. See, I'm good at getting
it on the ground. In fact I did that almost immediately!
ALAN ALDA (NARRATION) One of Pointer's biggest users
is the US military. It was employed in what are still
classified missions during the Gulf War, and here it's
beaming back aerial shots during an exercise at Lackland
Airforce Base in Texas. Flown with an infrared camera,
the plane can easily spot enemy troops at night. Recently
the Defense Advanced Research Projects Agency began
funding the development of planes even smaller and stealthier
than the Pointer. To Paul MacCready, the challenge was
PAUL MACCREADY Only weighs a couple of
ALAN ALDA (NARRATION) Called the Black Widow,
this tiny plane is no heavier than the birds it's trying
PAUL MACCREADY Nature still with birds and
insects does it better than humans, but we're learning
a lot from them and we're getting closer all the time.
ALAN ALDA Is this some kind of tracking thing, or is
this just for fun? What is that?
PAUL MACCREADY That's
the Black Widow.
ALAN ALDA Oh I see.
That's the insignia that they use -- the logo that nature
puts on Black Widow spiders.
MATT KEENNON Throttle check…
ALAN ALDA (NARRATION) Matt Keennon has nursed the Black
Widow through most of its development.
3, 2, 1, launch.
ALAN ALDA (NARRATION) But this morning
its onboard camera records one of its less impressive
ALAN ALDA What went wrong there?
Um, there was a sequencing problem and um -- I'm not
ALAN ALDA (NARRATION) Two hours later, Matt
figures he's fixed the problem.
ALAN ALDA Is it ready
to fly now?
MATT KEENNON It's all ready. Just had a
connector come undone, and it's charged, ready to go.
ALAN ALDA (NARRATION) Incredibly, this six-inch wingspan
airplane, weighing no more than a slice of bread --
and looking like no airplane I've ever seen -- carries
an onboard video camera, three computers, an electric
motor and batteries to run it all.
MATT KEENNON Excellent.
Install it on the launcher.
ALAN ALDA (NARRATION) It's
launched from a compressed air catapult.
Cross your fingers. 3,2,1 launch.
PAUL MACCREADY I'm
ALAN ALDA Oh, that's great.
ALAN ALDA (NARRATION)
The batteries on board today limit the flight time to
just a few minutes. But with the batteries it will use
in the field the plane can fly for over twenty minutes.
ALAN ALDA There we are, there we are.
ALAN ALDA (NARRATION)
It's so fast and quiet that an enemy probably wouldn't
even notice it, let alone be able to shoot it down.
MATT KEENNON Now can anybody hear it?
ALAN ALDA Just
barely. Sounds like a fly.
MATT KEENNON And it's right
overhead. So when it's a few hundred yards away you
literally cannot hear it.
ALAN ALDA (NARRATION) In combat,
the tiny spy plane is disposable. Its mission done,
it simply crashes.
MATT KEENNON All right. What you
call a belly landing.
ALAN ALDA (NARRATION) But this
developmental model will get to fly again.
And here is a little fin that came off. Just one.
MATT KEENNON Right.
ALAN ALDA Is the propeller intact?
MATT KEENNON Well, it's a little bit damaged but those are
disposable. Again we just pull it off, put on another
ALAN ALDA Did you ever think that you'd see this
flying like this?
PAUL MACCREADY We never even dreamt
such things could exist when we started on this round
about three years ago. We didn't dream that it could
end up so successful, and if we had imagined it, then
we could have leapt to the solution, we would have saved
ourselves three years.
MATT KEENNON You have to give
Paul a lot of credit. I've been working on this for
the last three years but we use his inspiration, his
design ideas of evolving a design and trying things
and just go out and try it and don't try to analyze
the hell out of it. And that helped a lot because this
is a very unconventional design we ended up with.
PAUL MACCREADY The pioneering is the exciting part, and somehow
at Aerovironment we've accumulated just the most wonderful
staff of inventive people. The problem is to keep everyone
from being too inventive or we wouldn't get any work
done, we have to keep beating people down saying, no,
focus on the project. The people who work here are dynamite.
ALAN ALDA (NARRATION) Aerovionment's inventiveness is
now paying off in a plane whose mission is literally
out of this world.
ALAN ALDA This could fly on Mars?
CARLOS MIRALES This could fly on Mars, right.
How do you know this could fly on Mars?
Well the atmosphere on Mars is a lot like it is here
on Earth at 100,000 feet.
ALAN ALDA So your planes are
CARLOS MIRALES Our experience is very good
for designing airplanes that fly on Mars. This airplane
actually folds up, a lot like this little model right
here. The wings fold, fuselage folds down like that,
and the tail folds down over that to fit inside a small
probe which is carried by a spacecraft all the way to
Mars. When that probe enters the atmosphere, it will
open under a parachute, the airplane will unfold, release
the parachute and begin flying along the canyon walls
ALAN ALDA (NARRATION) Looking uncannily like
a flight on Mars itself, this was actually a test of
the plane flying in Red Rock Canyon, in California's
Mojave Desert. But within the next decade, the plane
could be flying along the walls of the largest known
canyon in the solar system, the 2500 mile long, 6 mile
deep Valles Marineris on Mars -- giving us a bird's
eye view of a place where, as far as we know, birds
have never been.
TO THE AIR
ALAN ALDA (NARRATION) The pioneers of flying free were the
insects… They first took to the air a third of a billion
years ago. One of the world's great students of insect
flight is George Ruppel. Among his favorite subjects:
GEORGE RUPPEL Here we have caught a large
dragonfly, one of the best fliers we have.
(NARRATION) And dragonflies not only have powerful wings
GEORGE RUPPEL Always, it will bite me. Ouch.
(NARRATION) We met George Ruppel a few years ago in
Germany, where this marsh is one of his favorite spots
for stalking dragonflies.
ALAN ALDA How do you look
for them? Do you scan with your eyes or do you --
GEORGE RUPPEL Yes, I scan with my eyes and then I detect the
blue and black bodies.
ALAN ALDA (NARRATION) 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?
GEORGE RUPPEL Yes,
controlled, but the dragonflies 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, film
ALAN ALDA (NARRATION) 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 percent 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.
JIM MARDEN Have
you seen him before?
MELISSA KRAMER No.
ALAN ALDA (NARRATION)
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.
JIM 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.
ALAN ALDA (NARRATION) And it was while watching insects on
water-- especially a group of winged but flightless
insects called stoneflies-- that Jim Marden suddenly
saw what good a half-wing could be. Stoneflies often
emerge from their larval form in the middle of a river,
and need to get to shore quickly in order to find a
mate. Stoneflies 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.
JIM MARDEN OK, I'll see if we can get one.
ALAN ALDA (NARRATION)
Back in the lab, the Pennsylvania State University biologists
found their stoneflies to be highly cooperative, behaving
in front of a high speed video camera just as they do
in the river.
JIM 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 the tip of her abdomen pulled off the water there.
The trick the 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
ALAN ALDA (NARRATION) 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.
MELISSA KRAMER What I'm
doing is videotaping these stoneflies surface skimming
from above, with a centimeter (inaudible) 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.
ALAN ALDA (NARRATION)
With the slow-motion replay, Melissa can count the number
of video frames it takes for the stonefly to skim a
certain distance. The insects average about 1 1/2 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 stoneflies 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
JIM MARDEN Well the Darwinian idea of
evolution is a gradual, step-wise 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 stoneflies is showing what nubs of
wings really are used for.
ALAN ALDA (NARRATION) Most of the airplanes Paul MacCready
has made in his life owe little to flapping winged insects.
But not all.
ALAN ALDA Is this going to flap its wings?
PAUL MACCREADY It will flap and fly beautifully -- unless
I bust it while I'm assembling it.
ALAN ALDA How many
hours did it take to build this?
PAUL MACCREADY 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 times.
ALAN ALDA So you might
be able to get that to come back to you?
Once it's going right it goes around in circles that
are about eight feet in diameter. You can practically
fly it in a phone booth.
ALAN ALDA Do you ever expect
that a plane that will be used for something will fly
this way by flapping? Or is this…
PAUL MACCREADY Passengers
on a 747 would really be irritated if it went like that.
But it's virtually identical to things 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 a 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 development
and inventions 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, prrrr, 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 that.
ALAN ALDA Well that sounds useful.
PAUL MACCREADY Yeah, it has its merits.
ALAN ALDA (NARRATION)
For Paul, flapping wings may once have been more entertaining
PAUL MACCREADY Ah, give it another three
or four, what the heck.
ALAN ALDA (NARRATION) But as
we'll see in a moment, there are plenty of missions
beyond scaring a teenage sibling that a tiny flapping
flyer could perhaps one-day take on.
Now we'll see if this gets a turn. OK. Yeah, that's
a little more like it. Of course, if a thermal comes,
that's the last this will ever be seen… If it lands
in the bush that could be the last it's seen, too. It
doesn't get hurt.
ALAN ALDA No. It's OK. It's pollinating
PAUL MACCREADY For some reason or other,
kids like this. CEOs of billion dollar corporations
like it, they all want one. And the fact that they can't
have one makes it more appealing to them.
ALAN ALDA (NARRATION) One multi-billion dollar organization
that wants a tiny flapping flyer 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 flyers --
including one at Georgia Tech.
ROBERT MICHELSON If you're flying in close quarters
you've got to be able to fly slow. If we were to make
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.
ALAN ALDA (NARRATION) This simple
wind-up model has the twin flapping wings of the machine
Rob Michelson ultimately hopes to build. But like others
tackling the same problem -- including Professor Yu-Chong
Tai at Caltech in Pasadena -- designers of flapping
wing flyers a difficult problem. Making a wind-up 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
YU-CHONG TAI So we may run into a dead end. I
mean, 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. You have to design
more efficient wings that would generate the lift to
carry the weight.
ALAN ALDA (NARRATION) In their search for more efficient
wings, the Caltech researchers have linked up with scientists
at UCLA -- hoping to learn the heavy lifting secrets
UCLA STUDENT This is a cicada wing I'm about to mount.
It's one of the larger insect wings. It's also one of
the stiffest wings we have.
ALAN ALDA (NARRATION) The UCLA researchers
have been flapping a variety of insect wings in a 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.
MATT KEENNON That looks fabulous. What's the projected
weight for these wings after they're cut out?
CALTECH GUY Perhaps about a few hundred milligrams.
ALAN ALDA (NARRATION) We joined
the group one-day in 1999, when the insect-inspired
wing was undergoing flight tests… And when it was quickly
obvious that insects still know a thing or two that
aeronautical engineers don't.
MATT KEENNON 3, 2, 1,
launch. It's trying.
YU-CHONG TAI We 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.
ALAN ALDA (NARRATION)
Almost-but-not-quite flying is another entry in the
flapping wing derby, built by a team at SRI International
in Palo Alto. They too know that somehow they've got
to find an extra source of lift
DAVID LOEWEN 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.
ALAN ALDA (NARRATION) In the
slow motion effect produced by a strobe light, the wings
can be seen folding together and peeling apart.
DAVID LOEWEN 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 helps in the
generation of lift. 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 2 times the lift.
ALAN ALDA (NARRATION) The wings'
complex motion may be based on biology, but he 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 micro-flyers - 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 eighteen months ago in favor of wings that
look uncannily like the ones his boss used to make 65
years ago. It may seem unlikely that the MacCready philosophy
of testing and tweaking, testing and tweaking, will
ever produce a machine that can fly like a bird. But
that's what they said about a plane powered by a person.
ALAN ALDA He's got it. He's got it on his head!
(NARRATION) 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
TYLER MACCREADY We'd chase it like this for
ALAN ALDA (NARRATION) When they got bored with
their father's project, they invented an extraordinary
little plane of their own.
TYLER MACCREADY And I can
control it by putting the lift on one side of the wing
or the other.
ALAN ALDA (NARRATION) They called it their
ALAN ALDA I've never seen anything
like that. How old were you when you invented that?
TYLER MACCREADY Oh, 10, 11, 12… something like that.
ALAN ALDA 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
ALAN ALDA Excuse me.
TYLER MACCREADY The launch
is the most difficult part.
ALAN ALDA (NARRATION) Well,
maybe the part right after the launch -- though Tyler
is politely encouraging.
TYLER MACCREADY Excellent.
You're getting it. Now the second challenge is, what
you did there was to get your hands behind which actually
puts lift near the trailing edge and that makes it dive.
ALAN ALDA You need to get your hands under it, huh?
TYLER MACCREADY Yeah, it's like a balancing act.
ALAN ALDA You need to get your hands right under it?
TYLER MACCREADY To get your hands just in the right area,
so that the lift is lifting the wing.
ALAN ALDA Oh I
see, not behind. And this way it keeps the air going
up into the wings, so I want to get them like that.
I see, I couldn't see that's what you were doing.
TYLER MACCREADY But also if they're too far forward it will
stall and slow down.
ALAN ALDA Right.
ALAN ALDA Got
it, got it. Had it for a few seconds.
That was great. Now the next challenge is to get it
flying up in front of your face, and you can actually
take your hands away.
ALAN ALDA That thing with the
head must be very hard to get.
TYLER MACCREADY Did you
see how it jumped up as soon as your head got under
ALAN ALDA When my head got under it it really
TYLER MACCREADY Young kids can pick this
up pretty quick, because it does involve a bit of balancing,
so you have to learn the skill for it. But you did a
fantastic job. I was amazed, especially even getting
it up on your head some.
ALAN ALDA Well I just got a
couple of seconds. But it's amazing to see you control
it with your head. It looks almost magical. And the
most amazing thing is that you figured this out when
you were ten years old. That's incredible. There's all
this brainpower that other ten-year-olds must have that
we're not making use of.
TYLER MACCREADY Absolutely.
All we did…we didn't actually set out to invent something;
all we did was keep pushing the limits of what we were
capable of doing, which is very common with any kind
ALAN ALDA You were just playing, and it looks
like your Dad keeps playing no matter how old he gets.
TYLER MACCREADY And pushing the limits of what his toys
are capable of.
ALAN ALDA (NARRATION) Pushing the limits
of what his toys are capable of. That's what Paul MacCready
has been doing with his toys for over 65 years now.
And not just pushing the limits -- often going far beyond
the limits of conventional airplane design. Lighter…bigger…
slower… higher…smaller… quieter… all the time inspired
by his boyhood dream of flying with the birds -- a dream
that even at the age of 75, is still very much alive.
PAUL MACCREADY I want to make a stable silent airplane
that I can fly around in and look at scenery and have
a good time that's as quiet as my car inside and out.
And have them fly with the birds would be a delight.
ALAN ALDA (NARRATION) It was in the still air of another
early California morning that I came to say goodbye.
ALAN ALDA What are you working on?
PAUL MACCREADY Well,
playing with may be more of the right word, though some
of these silly things eventually result in something
ALAN ALDA (NARRATION) And on this
morning what Paul happened to be playing with was a
model of the very plane in which, some day, he hopes
to fly with the birds.