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				Is It a Bird? Bird-watching inspires a glider that soars almost as well as the real thing.
		Select text to jump ahead in the clip: 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.
		Select text to jump ahead in the clip: 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.
		Select text to jump ahead in the clip: 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