"Okay let's rig this angel to fly" "It takes a lot more than feathers and glue to get humans up in the air" "It looks good Let's take her up" "The desire to fly is as old as human culture" "Ancient Egyptians studied birds to learn how to fly" "Centuries later we were still strapping on wings jumping off cliffs and crashing" "It took a while to figure out that we were too heavy and too weak to propel ourselves with flapping wings" "But in this century our dreams of flight have become a reality" "While we haven't grown wings we have learned how to fly by shaping metal and plastic into machines that take us higher and faster than birds could ever fly" "Our ability to fly has changed the way we live and perceive the world around us" "In this life we live we are always in a hurry" "Oh, I could" "I couldn't do business without flying" "It, it actually makes me physically ill to fly" "But, um, I'll risk it 'cause I you know you can't't drive there" "Flying always means vacation" "I'm leaving on a safari to ah, eastern Africa" "I'm a big fan of peanuts" "When once you get into a plane it's like getting into a time traveling" "It's a tube" "So speed is the thing" "But even frequent flyers packed into the belly of a four hundred-ton metal bird don't really understand how it works" "Rear propulsion and some airlifts and..." "I I'm pre-med" "So you think that I after all the physics classes" "I'll know something" "But..." "I know it has to do with the wing design" "The gust of air shooting up I, I guess..." "The wing, I think ...or coming down" "I'm not sure which way" "I would just assume ah random air currents" "I really don't know" "I think the plane goes fast enough to get enough air through the engine" "Propellers make it go up and down" "Jet, Can't remember The wing..." "Propellers ...is fatter at the front and then it's streamlines out" "The air lifts it" "Okay Air's always important" "Ah, ha" "It's pretty impressive that it all works" "Every time I get up there" "I think how in the world is this happening?" "He is not the only one" "But the secret of flight can be broken down into four principles" "Thrust, lift, weight and drag" "First we need a forward motion and that requires thrust" "This allows an upward force called lift to get us up in the air and to keep us up there" "Overcoming the force of gravity or weight and the resistance of the air a force called drag" "To understand these principles you need to understand the substance we fly in, air" "Birds balloons and fighter jets all fly in the sea of air we call our atmosphere" "Gravity holds the atmosphere to the earth the same way it holds you to the ground" "Since we live in it and can't see it it's easy to forget that air has weight and substance and that it flows and has pressure just like water does" "If you happen to be at sea level you're carrying around about the weight of a compact car on your shoulders" "You don't feel it because you're supported by equal air pressure on all sides" "And if you dive to the bottom of the swimming pool you can feel the pressure increase" "Well, it's the same with air" "Pressure increases at the bottom because there's more stuff on top" "But the light bulb really goes on once you understand how the air and a wing work together" "But then there's a moment..." "that it all comes together" "And I think prior to that moment where you're putting the the aspects of flying together seems the, um hardest on you at that time because you understand this and you understand that and, ah, but then how do they correlate?" "And then finally at one moment you see why at a certain speed suddenly total lift is possible" "Air is up" "John Travolta's been flying since he was sixteen" "Off and retracted" "He's logged over four thousand hours since then and now flies his own Lear jet" "Gulfstream II and a Canadian fighter jet back and forth to shooting locations and we're at cabin's climbing" "He gets asked a lot of questions about how lift works" "People, ah, ah, ask me continually" "I don't understand how a plane that heavy can get in the air"" "And then I always tell them to when they're driving you know at least thirty miles an hour if it's safe to do so roll down your window stick your hand out" "This is something that every child has done who who has at least thought about lift" "When I... thrust my hand out the window and turn my hand down like this and deflected some air it forced my hand up" "The air flows faster over the top of your hand than it does under the bottom just like it does over a bird or plane wing" "And by cambering it in other words giving it a a shape of this birds' wing for example where you have some curvature in it you can get even, a, a sensation of more lift" "As the speed of a fluid-like air increases the pressure decreases" "And finally the pay-off" "The faster-moving air over the top of the wing exerts lower pressure so that the higher pressure air underneath the wing pushes up and gives us lift" "For the air to flow faster over the top of the wing it has to hit the wing at a particular angle" "This is angle of attack" "So an airplane's what we say "Operating range"" "or its angle-of-attack range in which it makes lift is actually quite small" "It's only about ten degrees" "Whereas ninety degrees is straight up only about ah eleven percent of that from horizontal to straight up is actually used" "So there's a thin line between lift and stall" "Then if both an airplane's maneuvered too much then it becomes non-linear" "In other words if you pull back further it doesn't get more lift" "It has a stall And then it does bad things" "Down we go Forty, fifty, sixty" "This is gonna be a wild one This is gonna be" "Recovered?" "Pilots are trained to know how to avoid becoming non-linear" "Still stalls happen" "Whether they're studying linear or non-linear flight airplane designers examine airfoils which look like a wing slice to see how air will flow around them" "You know actually the hand is a very poor wing ha, as you might expect" "It's draggy because It's, it's, it's, ah, blunt" "Ah a perfect airfoil is very round like this on the front and sharp" "Ah, thin on the back and smooth" "So, a beautiful wing like you find on a sail plane or a high-performance airplane is mainly impressive because of its drag rather than because of its lift" "It has very low drag" "Laminar flow air moving smoothly over a surface is what the experts dream about" "Engineers in the '30s called it streamlining" "The term entered the language and the technique inspired decades of design" "Box shapes were banished and curves were in" "One of America's preeminent streamliners is Burt Rutan" "In stark contrast to the pyramid he lives in he conjures up planes with curved flowing lines" "And when I'm designing a wing" "I think first about what I want to do with the air" "Uh, if I want an airplane to be very efficient" "I take a lot of air and move it just a little bit down" "And you do that with a long-wing airplane" "A short-wing airplane like a fighter that that it has real short wings it has to take less air and move it more energetically down" "!" "uAnd in doing so it it's it's not as efficient" "It causes more drag" "And walked out of the hangar !" "v" "Rutan designed these planes so that you could build one in your garage" "A cross between a Wasp and a Star-Wars fighter" "Rutan named this horizontally - challenged plane the Long Easy" "Pilots called it a clean ship because it streamlined" "And it doesn't have lots of struts and wires sticking out to cause drag" "Another one of Rutan's attempts at turning the world of aviation upside down" "Some people actually enjoy this kind of thing" "I like to take off roll inverted... and fly out to my practice area" "It gives me a much better view of everything anyway" "So and I like to be upside down" "It, it stretches my back out and feels good" "As long as the angle of attack is right it doesn't matter which surface of the wing is facing up" "But aerobatic planes are designed to fly upside down" "The shape of the wing is very specific to an aerobatic airplane in that it's it's considered symmetrical so that the airflow is the same whether you're upright or inverted" "So you can fly the plane inverted almost in the same attitude with the same nose position as you can when you're upright" "So we're learned how to fly inverted fly faster and fly higher surpassing the birds in the sky" "But some still look to nature's flying creatures for inspiration" "I think all pilots are inspired by nature and inspired by birds" "And a lot of times when I'm up flying" "I'll see a bird sort of circling around a hawk maybe watching me or or an eagle sometimes" "And, and, um, yeah" "And we're all kind of jealous I think too, because they do it so effortlessly" "If you had a cloud's eye view this is what you would see birds capable of reaching speeds over one hundred miles an hour" "others navigating halfway around the globe soaring effortlessly on the wind for hours and performing aerobatic maneuvers that would make a fighter pilot's head spin" "They they have enormous flexibility" "They can put their wings forward or aft or up or down or change" "In fact every feather on a bird a bird may have ten thousand feathers and every feather is a control surface" "Every feather he can feel the local air on whether it's smooth or turbulent whether he can lift more there or less" "And he can change his shape ah, instantaneously enormously in terms of changing the direction of flight" "They're much more maneuverable than the best fighter" "So a bird really in every way oh my gosh look at these wings" "In every way is a lot more interesting than a little old fixed-wing airplane isn't he?" "Oh boy!" "Birds serve as living blueprints of the theory of flight" "But it wasn't always that way" "Nature has taken millions of years to turn them into the flying machines they are today" "The architecture of a bird is what makes it such an efficient flier" "Their hollow buoyant bones combine lightness and strength" "Powerful breast muscles drive the stroke of the wing" "And these wings do it all thrusting them forward and creating lift" "Thrust comes from the primary feathers at the wingtips which act almost like propellers" "The tips twist up at an angle to the rest of the wing" "They bite into the air like the blades of a propeller pulling the bird forward" "At the same time the rest of the wing provides the lifting surface to stay aloft" "But the pioneers of flight were victims of a common" "Misconception that birds swim across the sky propelled by a backward and downward wing stroke" "We attempted this flapping-winged flight" "But our wing envy resulted in broken bones and bruised egos" "The human body is not designed to fly" "But if we were to go back to the drawing board and make some changes it would take more than just a set of wings" "Muscle-powered flight would require big shoulders really big shoulders to anchor the muscles necessary to thrust us forward and up" "And underneath those muscles hollowed bones for lightness and a more streamlined shape" "It might not be pretty but it would get us airborne like the birds" "Birds were the motivation for... humans flying" "They were the symbols the thing you saw and certainly have given humans a great craving for flight" "The secrets of lift and drag are older than the first bird" "The laws of nature and properties of our atmosphere are the same for a falcon as they are for an F-14" "But the lift and thrust combined in nature's design had to be separated in order for humans to fly" "The closest we could come to bird flight is soaring using fixed wings for lift and the earth's's downward pull for thrust" "Without gravity..." "you couldn't glide" "So that's what puts is pulling you down" "That pulls you far And then you hopefully you catch air which is being moved up and down by the varying densities and being acted on by gravity" "And that's what pushes you back up again" "Gravity is the thrust" "Unpowered flight means learning how to use the movement of air..." "its ripples currents and rising columns" "You watch birds in flight" "Uh, that if they're spiraling up there's a thermal air you go over and join the bird" "Sometimes the bird will see you spiraling up and it'll come and join you" "You literally feel like you are floating looking down at the earth" "You have a full hemisphere of vision below you" "And, ah, it's very quiet" "There's also this that magic moment when you fling yourself off a cliff and don't die" "It's sort of like death and resurrection" "And then you land after a flight and you're you're still alive" "It's, it's quite a feeling It really is" "Every year the Birdman Rally brings that magic moment to Japan where teams make their own innovative gliders and compete for the longest glide" "But gliding still isn't enough" "We continue to be obsessed with muscle-powered flight" "About twenty years ago" "Paul MacCready designed a human-powered plane the Gossamer Albatross" "Powered only by the pilot's peddling the Albatross flew twenty-two miles across the English Channel" "Well everybody, somehow wishes they could do human-powered flight" "It's a instinct that maybe all humans share one way or another" "The energy needed to drive the propeller and move the Albatross forward was almost more than the pilot could manage" "And despite his physical conditioning he barely made it" "The problem is humans just aren't strong enough" "But when you look at all the numbers it turns out that to have a plane that is safe enough ss... stable, uh, structurally sound enough to hold a person ah, to keep a person aloft to be able to climb a bit" "it takes about a minimum of three horsepower" "And that's a factor of ten more than a person can put out" "Hoo, hoo, hoo!" "Whoo!" "So we've come to rely on machines to give us the power to thrust ourselves forward" "The rubber band on a toy plane acts as an engine does providing the energy to move the propellers" "Propellers are like a spinning wing" "Like a wing they produce lift but in a forward direction" "Propellers are airfoils when they bite into the air and it creates lift and it thrust just by the movement going through the air" "It's just a big windmill basically" "So now if we take a piece of air here and we push it aft it takes a force to do that" "And that's's the force that's thrust" "Propellers and piston engines have been pushing and pulling planes across the sky for ninety years" "Well, I can remember one day uh, looking up and know, uh, that probably the same airplane route that a propeller plane was on was now a jet" "And that was captivating that as a child" "I was watching technology change in front of my eyes" "So to fly higher and faster we stopped soaring like the swallows and started squirting like the squid" "Creatures like octopus squid and jellyfish all work on the same principle as a jet engine action and reaction" "So the fuel goes into the engine" "It's converted into work by speeding up the air increasing its energy as it goes out the back" "And that difference then provides a thrust" "John Travolta's Gulfstream II has two Rolls Royce jet engines each producing almost twelve thousand pounds of thrust" "This is an over-powered aircraft" "A plane thirty thousand pounds heavier than this plane is run by the same engines" "The British aircraft ah, 111 which is an airliner" "So you have that level of ah, of excess of power" "I like overpowered airplanes..." "Three thousand" "They thrill me..." "because in an emergency you have more than you need" "And, um, it gives you a sense of of well-being on a certain level" "For some pilots it's more than a sense of well-being" "Its speed is life" "The faster..." "that you end up going it's, ah, there's a lot of things it does for you" "One, it gets you through a threat area quicker" "And two, it's gonna it doesn't allow missiles to track you" "Roger that" "If somebody's shooting at you you try to go a little bit faster" "Ah, or if you're trying to catch somebody you try to go a little bit faster" "And the afterburner is simply a way... to get a, a short dash what they call dash speed so that you can get into or out of trouble, ah, just as rapidly as possible" "Can you do it?" "Well, an afterburner is ah, it, it's really pretty simple" "Ah, it, uh, that you take an extra piece of pipe and you put it on the back of the airplane" "And then you dump fuel into it" "The fuel ignites and it goes zooming out the back" "And you get a lot of power for that but it also costs you a lot of fuel" "What you're trying to do is you're getting enough thrust going out the back side that it equals the amount of weight that you're carrying" "So that's when you start hearing ratios" "Where you hear a one-to-one ratio is what you like to have from a fighter" "Well, the F-18 has about a one-to one point one-to-one thrust-to-weight ratio" "With that much thrust a pilot can stand on his tail and for a moment forget about gravity" "But just for a moment" "Well, I had mentioned to my parents that that I wanted to fly when I was about ten or eleven years old" "And they said, well, Patty, you know, women women don't become airline pilots" "So you can kind of forget that I was brought up around it and I remember, um, going out and seeing my dad when I was four or five years old at the airport" "And he, you know he pull me up into his big airplane and set me down" "We go taxiing around" "I always knew that I wanted to fly" "I might have twenty-five maneuvers doing anything from vertical maneuvers where I let the plane slide backwards through its smoke" "And that always gets a good reaction from the crowd" "Or maybe a torque roll where the plane is rolling going vertical and then sliding backwards through the smoke going vertical straight down" "Um, we like to do tumbling maneuvers where the plane's tumbling end over end" "And people think the plane's just totally and it is out of control" "So they're right" "National Aerobatic Champion Patty Wagstaff is anything but out of control" "It takes precision and skill to turn cartwheels in he sky" "The ability to keep these maneuvers under control is essential to flight" "Control surfaces are the movable parts of the wings and tail that allow the pilot to deflect the passing airflow and pivot the plane in the desired direction" "So there are three axes in an airplane" "And the three are yaw which is when the plane goes side to side" "And that controlled by the rudder" "Pitch is when the plane goes up and down" "And that's controlled by the elevator" "And roll is around the longitudinal axis and that's controlled by the ailerons" "What, when you roll the airplane you're rolling the airplane along the longitudinal axis" "So if you draw if you take a string and you put it right down the middle of the airplane and then you move the ailerons and you move the wing you're gonna roll the plane around that string" "And that's what a roll is" "Patty Wagstaff may be on a roll but most pilots try to avoid that sort of thing" "They want stability" "Most general aviation planes that people are flying around the pilots have a lot of stability built into those planes" "And they're flying around and they put the plane into a dive and they take their hands out hands off and the plane will oscillate until it returns back to straight and level" "Well, my plane and most aerobatic planes are not designed for that" "So if I take my hands off the controls the plane will probably go off into a roll go into a dive and stay there" "It's not gonna want to come out" "And that's really good for aerobatics" "The connections between the pilot and the control surfaces in most small planes even aerobatic ones is mechanical, Cables pulleys and levers do the job" "Uh, in a small aerobatic plane like mine" "Um, it's very very simple It's just" "So, when I move the stick to the right" "I, all I'm doing is pulling the tube over and it's deflecting the ailerons" "And the same with the elevator" "I'm just pushing and pulling tubes that get connected to the control surfaces" "But fighter jets are a different story" "The shape of the planes and the giant engines that make them fast also make them temperamental and inherently unstable" "Human beings and mechanical connections just are not quick enough to keep these jets under control" "So fighter pilots are teamed up with computers in a system called fly-by-wire" "The control is operated especially like in a jet like this one to fly-by-wire system which means computers are trying to help you out trying to fly the jet as best you can" "It's gonna get the control surfaces moving to their utmost that's everything is still the same when you're feeling the stick" "There's gonna be artificial feels that are put in there that allow you to can feel the actual control surfaces move" "Now, your moving the stick isn't actually moving the control surfaces" "It's just a series of bungees set up to give you that artificial feel" "It's very much like the brake system in your car or the steering system" "It may feel like a mechanical connection but an onboard computer is sending digital instructions to hydraulic activators which in turn move the various control surfaces" "Or you can fly the computer without the plane" "Flight simulators have been best-sellers since the coming of the home computer" "This one is modeled after the control system of an F-18 jet" "But it only hints at the complexity a fighter pilot faces" "Flying a fighter plane it's like playing two pianos at the same time 'cause of all the buttons and dials and things you have to work at once just to make the airplane fly and fight" "And it takes literally a year to do that, to, to learn how to fly the airplane and then how to fight the airplane" "The thing is we've gotten to the point where computers help us out enough that we can then have aircraft do things that they were never able to do before" "In fact, there's aircraft out there today that cannot be flown unless the computer systems are helping out the pilot do his job" "While a 747 thankfully doesn't do the kind of maneuvers that a fighter jet or aerobatic plane might do commercial aircraft also use computer systems to move their control surfaces" "As passengers on a Boeing 777 watch movies thirty-five thousand feet over Newfoundland the computers are busy displaying readouts recording every critical function of the airplane and crunching numbers" "Total flying time will be no more than two-ten, I'm sure" "Even a small corporate jet like John Travolta's Gulfstream II is computerized" "Even with, ah medium-range technology which is what I'm used to" "I'll kick off the autopilot and fly an approach on my own just to feel it You know, ah, ah," "I think there's still the urge to be a pilot" "And that's why airplane designers have to take into account human limits in creating their flying machines" "And I've been up in several military jets" "And, and, ah, you know flown a lot of airlines and hand handled the controls of 747 s and things like that" "And they're flying" "And especially these military pilots" "I think a lot of the, ah, small aerobatic pilots ah, that pull a lot of Gs it's easy to go hey, you know" "We pull more Gs than you do" "But in a military plane the Gs are sustained" "Pilots call gravity's powerful force on the human body Gs" "They are brought on by sudden changes in attitude or speed" "Gs are just, ah the force of gravity" "And when we're walking around the earth and our feet are on the ground we're being pulled by one force of gravity one G" "When you go up in an airplane or in a car you experience more Gs" "So anybody that's gone around the curve of a car and gets thrown to the outside those are Gs" "As an airplane moves through a curve the acceleration creates high G forces that drive the pilot toward the bottom of his chair" "High positive Gs drive a pilot's blood away from his brain and toward his feet causing a blackout" "Body conditioning and special gear can help prevent that" "No matter how high-tech the plane or well-trained the pilot things can go wrong" "Well, there are a lot of things that can go wrong" "The engine can quit" "Uh, you can have an engine failure" "Um, you can have a propeller failure" "You can lose a piece of your propeller" "Uh, you could have a structural failure" "Um, something could break in the airplane" "Those are the main things You could have a fire" "I, I think that if you experience terror in the airplane you're not gonna be doing our job properly" "And I, you know I've had emergencies" "But you need to just react to those things" "You can't be afraid because then you get frozen with fear" "On a cloudy night in 1992 while flying his family to their vacation home" "John Travolta's entire electrical system failed" "Landing without a radio and little navigational gear took Travolta back to the way pilots had to do it in the early days of aviation" "On a very rare occasion you get, ah, an electrical failure" "And in my situation ah, there was, ah, several consecutive electrical failures" "I'm dead" "From my early days of learning how to fly you learn even from being in a single-engine plane that, ah, if you were in IFR conditions you find a hole in the sky if you can" "And you spiral down through that hole and then proceed to locate an area to land" "And in this case ah, I was able to do that" "I found a hole in the sky spiraled down" "And, ah, hovered over Washington and landed safely" "And the guys from the tower and, ah, some other officials came down to shake the hand of the pilot that safely landed the jet at National Airport" "And then they found out it was me and that was even more interesting" "Ah, but, ah, I was very proud of that moment because I felt that all the years I went to school it paid off" "And even my earliest training paid off where, ah, you learn" "Ah, to fly a plane when you lose everything" "Ever since the first powered flight designers have tinkered with airfoils engines, fuels and materials to coax more speed from their crafts" "The problem lies not so much in reaching the speed of sound somewhere around seven hundred sixty miles an hour at sea level but in overcoming the severe punishment an aircraft takes as it approaches that speed" "Here's why" "Much like the wake of water at the tip of a boat a plane creates a wave of pressure ahead of it no matter how slow or fast it flies" "When an airplane travels below the speed of sound the air ahead of it flows out of the way before the plane reaches it" "But as an aircraft approaches the speed of sound it compresses the air in front into a dense's shockwave" "On the ground you can hear that shockwave as a sonic boom" "Aerodynamic engineers figured out how to slide through shockwaves with thinner streamlined wings and sharper edges that flew more cleanly through the compacted air" "But for a supersonic transport like the Concorde there are even tougher problems" "While it takes passengers from New York to London in less than three and a half hours the Concorde is considered an economic and environmental failure" "At low speed its streamlined shape doesn't produce much lift" "So getting airborne means enormously loud and powerful fuel-guzzling engines" "It holds only a quarter of the passengers and has half the range of a jumbo jet" "Engineers are at work on a better alternative to the Concorde a supersonic that will be more fuel-efficient and much quieter" "But most important the next generation supersonic will be able to carry three times as many passengers" "The idea behind a high-speed civil transport is to get a..." "supersonic airplane that can, in fact have the range to go from California to, say the Pacific rim in five hours which is a reasonable amount of time" "Most people can tolerate five hours of sitting in an airplane" "Engineer and pilot Marta Bohn Meyer heads a team at the Aeronautics Division of NASA" "They're working on better ways to reduce drag" "And again it's all about how air flows" "You've seen commercials on TV for example of cars in wind tunnels" "And they let smoke out in front of the car and the smoke runs along the hood of the car goes up to the the cab of the car and then it kind of billows out" "Well, where it's running along the car and it's staying down inside close to the car it's in in the laminar boundary layer itself or the layer of air that's flowing along the car" "The boundary layer is the thin layer of air that flows along the surface of an aircraft" "Engineers try to make it flow smoothly avoiding the dirty word of aerodynamics:" "Turbulence" "Smooth laminar flow is equal to less drag" "Less drag requires less thrust to maintain forward speed" "And lower thrust takes less fuel which means cheaper tickets for you and me" "And that makes everybody happy" "NASA is trying to come up with a way to create better laminar flow over the wing thereby reducing drag" "And they are doing it with a vacuum cleaner" "They are creating suction by fitting the wing with a second skin" "It's a kind of glove with about ten million microscopic holes that suck the air off the wing of an F-16XL" "Suction is being used in this particular experiment to control the boundary layer" "What we're attempting to do is take what is potentially turbulent air and we're trying to suck that back down suck that bubbly part of it back down inside so that it has a chance to establish itself back on the surface and flow smoothly" "And we're taking data for item eleven..." "The NASA team thinks they're on the right track" "This could translate into savings when the high-speed civil transport takes off" "The potential is that we could actually start designing supersonic airplanes with Delta-wing platforms and these airplanes would be seven to nine percent less draggy" "The return on that investment is clearly either a longer-range airplane cause now you don't have as much drag" "You can go further with this airplane" "Or you can carry more passengers" "Or fly even faster into battle" "Air power gives a third dimension to warfare" "Ah, land and sea combat are fought on the surface of the ground" "Air combat lets you do this" "You can see farther You can go farther" "You can attack your enemy in depth" "You can see what the enemy is doing" "You can bring the, the war to your enemy's capital on the very first day" "Author Tom Clancy researches the latest trends in military aircraft for his novels and his non-fiction books" "Let's assume for the moment that you, you, you have to go into a battlefield" "And you have a choice between being invisible and being fast" "What would you rather be?" "The military calls it low observables and high survivability" "In English that means if they can't see you they can't kill you" "Okay, When you talk about Stealth technology what you're trying to do is get an aircraft into an area unseen" "The re... the way that you see an aircraft is you usually either with a radar or by having some sort of a system that detects electrical signals that that aircraft is putting out" "They call it the black jet" "The F-117 is the invisible man of the aviation world" "The F-117 penetrated Iraqi air defenses undetected while making precision attacks" "As you see the, the the airplane is made of almost entirely out of flat surfaces" "Now radar is an electromagnetic wave of energy" "And when it hits a surface it bounces off" "When it hits a flat surface it pretty much all bounces off in one direction" "Now in the case of the ah, of the 117 a wave of energy comes in from the transmitter over here hits the aircraft and then bounces in another direction" "So nothing returns back to the transmitter" "And this guy might as well not even be there" "So you have to design the aircraft in such a way that A it can fly which is not an easy thing to do with this with an object made out of flat surfaces" "And B the the radar sig..." "the radar signals that hit it no matter what direction they come from are gonna go in the wrong direction no matter what" "While the F-117 is all angles the B-2 Stealth bomber is a smooth bat wing" "But both can slip through enemy air with relative impunity" "The Stealth aircraft aren't really terribly ah, terribly fast or terribly maneuverable" "But if they're invisible it doesn't matter!" "The ability to take off and land vertically keeping the maneuverability of a conventional airplane has long been a desire for the military" "Well, in case somebody rips up your airfields ah, you have to take off your airplanes from somewhere ah, which is pretty much why that was invented in order, order to take ah, fighter aircraft off" "from ships which are too small to do to be conventional aircraft carriers" "By using the downward thrust of an engine the Harrier jumpjet can dispense with the need for a runway and take off vertically from the ground" "Once it's up in the air the engine exhausts are swiveled backward and the wings provide lift in the normal way" "Unfortunately VISTOL technology" "Ah, has the disadvantage of being very fuel-inefficient" "Ah, it burns up a lot of gas" "It is, nevertheless a very useful capability" "You can deploy the airplanes right up with the troops instead of having to back them off to a runway that's, ah, ten thousand feet long" "We would like to show you a picture of the Pentagon hypersonic spy plane called the Aurora" "But they say it doesn't exist Yet, the rumors persist" "There are probably two very ah, unusual airplanes flying out of Groom Lake which is a, a base the Air Force just admit uh, admitted to exist though it's been there for an awfully long time" "Ah, and they're both very very fast" "And one of them's fighter size and one of them's's supposedly quite a bit larger" "And beyond that it's anybody's guess" "But there is something, there there's, the Air Force presumably the Air Force, ah, has, has a couple of very exotic, ah airplanes that they just don't want to talk about" "Or, as one engineer put it..." "If I told you I'll have to kill you" "It's a series of compromises flying in close formation" "And we like to carry that to its extreme" "It's just a big flying wing and it's like almost like a bunch of airplanes six airplanes all flying in close formation" "Although it has a wingspan longer than a Boeing 737 the Pathfinder weighs less than five hundred pounds" "It's big but also light a contradiction in engineering" "Paul MacCready and Ray Morgan designed this unmanned flying wing to fly very slowly and very high for weeks on end as it studies the earth's atmosphere" "It flew five miles high on its first altitude test and in future flights it will climb even higher into the stratosphere" "There's an interest in having vehicles that can move around in..." "the stratosphere the stratosphere above say thirty or forty or fifty thousand feet" "Uh, the next fifty or a hundred thousand feet is a mantle a layer ah of great importance to the world that in permitting some radiation to come in screening out other radiation really determines the existence of life on earth" "So you want to be monitoring and doing research that lets you understand what's going on there" "This is the the layer that protects us" "Cruising in the middle stratosphere requires about six times the power and speed needed at sea level" "Uh, as we go higher... ah, the density of the air goes down and the airplane has to fly faster in order to develop the same amount of lift" "Ah as we go higher and higher it takes more and more power to fly" "And in intern internal combustion-powered airplane ah, this is a big penalty and this limits the altitude they can fly to" "The higher it goes the less power you have" "But the Pathfinder is different" "It's powered by the sun" "The more of the surface that I have that I can cover in solar cells the more power I get" "The less surface I have exposed to the air the less drag I get" "And the less structure I have the less weight I have" "It drives you towards something that looks like just a wing" "And when the sun goes down the Pathfinder will keep going and going and going running on solar energy stored in its batteries" "While others compete for speed records" "MacCready and Morgan like going slow" "We focus on things that take very little power to fly" "Uh, the solar plane for instance flies on the power generated by about four average-size hair dryers" "And we can fly to over sixty thousand seventy thousand feet on that amount of power" "Um, so flying slowly has an advantage and it reduces the amount of power it takes to fly" "We have made flying machines that hover like hummingbirds punch holes in the sky dance ballet perform disappearing acts and surf the waves of the atmosphere" "For the pilots the passion is being in the air whether gliding at thirty miles per hour or slicing through the sky at three times the speed of sound" "The flying is sort of something that gives you an infinite challenge an infinite freedom" "It is a great feeling" "Flying gives me a chance to to just go express myself by myself do it the way I want to do it and not have to answer to anybody for it" "It's almost parallel to the feeling I have when I know a character in acting and it's on automatic pilot" "I don't have to think about it any more" "I just am it" "Uh, I know what fascinates me about flying is the freedom of it" "It's, it's just getting away from the ground looking down and you're free of all of that" "And sometimes when I'm flying" "I think this is the only thing in my life that really makes sense" "Come on, Joe Come on, Drive" "I know I should feel welcome here way up in the atmosphere but I am afraid..." "And if I land on earth again" "I'll be happy just to cut my face while I shave" "Oh, the sky is broken but I am on a cloud" "Oh, and right beside it I was not designed to fly" "To fly"