Reach for the Skies
Page 8
Lilienthal was also a practical inventor. Over six years, he made some 2,000 flights in 16 glider types, launching himself from various sites, including an artificial hill he built himself near Berlin. Based on his study of birds—and particularly storks—the gliders were recognizable prototypes of modern hang gliders, but with one vital (perhaps I should say lethal) difference: rather than hanging off them from his waist, Lilienthal wore his gliders on his shoulders. If his glider nosed up, he threw his feet forward. If his right wing rose, he shifted his weight to the right. It sounds precarious; and it was. On August 9, 1896, Lilienthal fell from a height of 55 feet and broke his spine. He remained conscious just long enough to remark to his horrified rescuers that “sacrifices must be made,” and died the next day.
Not long after this sad news, the Wright brothers stumbled upon another obituary. This time the newspaper reported the passing of Scotsman Percy Pilcher, Britain’s most important glider pioneer. A follower of Otto Lilienthal, he held the world distance record for flying his “hawk” glider more than 800 feet in the grounds of Stanford Hall in Leicestershire. It was as he was flying an experimental triplane for potential sponsors that the plane’s tail snapped; he plunged 30 feet to his death. The newspapers reported that the days of powered flight, surely just around the corner now, had suffered another small and tragic postponement.
Otto Lilienthal’s gliders were inspired by studies of birds in flight.
The brothers, reading between the lines of these two reports, began to wonder. First Otto Lilienthal; now Percy Pilcher. Both had suffered virtually identical fatal accidents. Could these great men have missed something vital about the nature of flight? The Wrights had little formal education, but they had been brought up in a house that made up in books and magazines what it lacked in creature comforts. The boys had enough self-confidence, if they didn’t know a thing, to make them go out and ask. They were brilliant, indefatigable researchers.
In May 1899, Wilbur wrote to the Smithsonian Institution for a reading list of technical works on aviation, assuring the recipient that he was “an enthusiast, but not a crank.” He received, by return, a whole caseful of journals and papers, generously thrown together by Richard Rathbun, the institution’s assistant secretary. Among the papers were articles by the American engineer Octave Chanute, who later championed the brothers’ work.
At the end of their reading, the brothers felt they knew what had killed Lilienthal and Pilcher. Both men had attempted to create gliders that were inherently stable. As a consequence, neither had developed any real system of flight control.
The Wrights knew this was the wrong approach, because they knew about bicycles. They knew that the faster you rode a bicycle, the more stable it became. Stop and you keeled over. Bicycles are not stable, but when they’re in motion, they are exquisitely responsive to the movements and adjustments of their riders. The Wrights’ breakthrough was to conceive an airplane that, like a bicycle, had no inherent stability but responded sensitively to the movements of its operator.
Like Otto Lilienthal and so many pioneers before them, the brothers had spent many hours watching birds. Among their observations was one that proved to be the key to their success. They had noticed how a buzzard handles sudden gusts by twisting its wing tips, lowering one tip while raising the other to maintain its stability. The story goes that, sometime in July 1899, Wilbur was goofing around with an empty inner-tube carton when it dawned on him: if you twist the ends of the box, the corner of one end goes up, while the opposite corner goes down. Imagining the box in flight, Wilbur realized that, by twisting, the box would alter the flow of air around it in a way that would cause it to tilt in the air, just like a buzzard. In his mind’s eye, this box in his hands wasn’t a box anymore: it was a wing—and what he had in his hands was the first-ever airplane control surface!
As eureka moments go, this one takes some unpicking. First, I’d better explain how a wing works in level flight to hold a body—an airplane, or a bird—up in the air.
Blow up a balloon and tie it tight. Squeeze the walls of the balloon. The air inside resists you. The further you squash the balloon, the harder you have to squeeze. That’s because you’re increasing the pressure of the air inside the balloon. So far, so obvious—and you’d be forgiven for thinking that whenever you constrict a fluid in this way, the pressure will increase. But there is one big exception to the rule, described by the Dutch mathematician Daniel Bernoulli in 1738, and it’s why birds—and planes—manage to stay in the air.
Bernoulli’s exception has to do with how fluids flow, and it’s most easily demonstrated not with air but with water. (Just to be clear: though water is much thicker than air, air and water are both fluids; they both obey the same physical rules.) Turn on your garden hose. Now pick a spot on the hose and squeeze. This time, the more constricted the hose becomes, the easier it is to squeeze!
This is what’s happening: Something—in this case, the pump that maintains the mains water pressure in your tap—has given the water the energy it needs to run through your hose. Some of that energy pushes the water forward, and some of it pushes the water against the sides of the hose. (If you punctured your hose, the water would fountain out.) The flow of water is constant; the same amount of water is trying to pass through every part of the hose. If you pinch the hose, then the water has to pick up speed to get through the bottleneck. More of the water’s energy is used to flow forward, which means less energy is available to push against the walls of the pipe. Squeeze the hose and the water pressure against the walls of the pipe decreases.
Let’s cut to the chase here and have a look at a cross-section of a wing. (This could be a bird’s wing or the wing of a plane. It doesn’t make any difference; they both work the same way.) Air passing from left to right in the diagram hits the wing. The wing squeezes the air passing over it. The air moves faster to compensate for the squeezing, and the pressure over the top surface of the wing drops. Planes and birds are sucked into the air.
So much for level flight on a calm day. What happens if it’s blustery? What if the air over your left wing is blowing harder than the air over your right wing? How do you stay level in real, unpredictable, constantly moving air? This is where Wilbur’s cardboard carton comes in.
A wing in motion sucks its payload into the air—with a little help from Daniel Bernoulli and his principle, first published in 1738.
If you progressively bend the front tip of your wing down, you will increasingly squeeze the air passing over it; the pressure over the wing will drop, and the wing will lift. If, at the same time, you progressively raise the front tip of the opposite wing, it will squeeze the air passing over it less, and the wing will drop. Orville and Wilbur proved this theory by attaching control lines to twist the sides of a box kite while in flight, in just the same way as Wilbur had twisted the cardboard carton. Sure enough, pulling the control lines made the kite roll over to one side or the other. Later, in combination with a movable rudder, this technique of “wing warping” would allow the Wrights’ machines to turn in the air with grace and ease . . . But I’m getting ahead of myself.
Evolution among the machines: a chart summarizing four decades of wing design.
The brothers’ kite experiments began in 1899, but they could never find enough wind. Wilbur wrote to the U.S. Weather Bureau and was told that they couldn’t do better than move their experiments to Kitty Hawk, a narrow beach off the coast of North Carolina.
Late in September 1900, Orville Wright wrote to his sister, “We certainly can’t complain of the place. We came down here for wind and sand, and we have got them.” Along with the wind and the sand came mosquitoes. Their arrival “was the beginning of the most miserable existence I ever passed through,” Orville complained. “They chewed us clear through our underwear and socks. Lumps began swelling up all over my body like hens’ eggs.” To make matters worse, there were precious few buildings in Kitty Hawk, and none for rent, so the brothers were living in tents.r />
The Wright brothers, Orville (front) and Wilbur, fly a kite at Kitty Hawk.
To begin with, they flew their prototype wings from a derrick 12 feet high, but the winds proved so strong and blustery they soon abandoned the tower and controlled their wings from the ground, as they would with ordinary kites. By the end of October 1902, Orville and Wilbur had become skilled pilots of their prototype glider. Launched from a nearby hillock with a daunting name, “Big Kill Devil Hill,” the glider carried its pilots hundreds of feet in each flight. It was time to add an engine.
They decided to build their own, ultralight engine, and gave the job to Charles Taylor, a young mechanic who worked in their bicycle shop. Taylor rose to the challenge. He shaved every fraction he could off the machine. He later recalled: “I cut the crankshaft from a solid block of steel weighing over a hundred pounds. When finished, it weighed about nineteen pounds.” Taylor’s four-cylinder engine used bicycle chains to drive two counter-rotating propellers. The Wrights had calculated that two propellers turning slowly would be more effective than one propeller spinning fast; and they arranged the propellers to spin in opposite directions so that the spin of the motors wouldn’t twist the frame of the plane.
While Taylor worked on the engine, the brothers worked on the propellers. These were much harder to make than anticipated. The Wrights assumed that there were figures and charts explaining the shape of a ship’s propellers, and that they could adapt these numbers to come up with a propeller ideally suited to the air. As it turned out, however, no one had ever done any serious work on the shape of ships’ propellers; they had simply evolved over decades of use! The Wrights had no choice but to figure their propellers out for themselves.
A propeller is a sort of moving wing. It works by creating a vacuum in front of the blades and a zone of high pressure behind. What makes it complicated is that, as Orville complained, “nothing about a propellor, or the medium in which it acts, stands still for a moment.”
Imagine trying to work out the speed of each point along a propeller blade without really knowing how fast the engine should be turning, or even how long the propeller blade should be! What the Wrights ended up with, after countless, long, involved arguments and many sleepless nights, was propellers of astonishing beauty, each blade twisted in a way that looks, with hindsight, perfectly natural, like exquisitely polished driftwood.
A propeller from the Wright Flyer: designed from first principles and carved by hand.
Indeed, much the same was said of the brothers’ whole invention. The sculptor Gutzon Borglum (the man who would later be given the job of sculpting U.S. presidents’ faces into Mount Rushmore) wrote: “It is so simple it annoys one. It is inconceivable, yet having seen it, it now seems the most natural thing in the air. One is amazed that human kind has not built it before.”
The machine that emerged into the near-freezing 30 mile-per-hour wind blowing across Big Kill Devil Hill launch site on Thursday, December 17, 1903, would carry Orville into the air and into the history books: at a ground speed of about 6 miles per hour, the Wright Flyer rose, dipped, and climbed into the air, on a flight that lasted 12 seconds and covered 120 feet.
It was the first airplane. And it was only the start.
four
The Golden Years
My life and my work have given me fantastic opportunities to fly in every imaginable kind of plane, from gliders to flying boats to jumbo jets. I have walked the wings of a biplane, crossed from balloon to balloon on a plank, hurled myself off Brighton pier in a less-than-successful attempt to be a birdman, and, for the TV show The Rebel Billionaire, I took one lucky contestant up a rope ladder, onto the top of the envelope of a balloon. We drank tea at 10,000 feet and gazed over the bowl of the earth. I have flown in warplanes and balloons, and for a few scary months I was even the backup pilot, in the Virgin Atlantic GlobalFlyer, for Steve Fossett’s transglobal flight.
I find it impossible to choose an absolute favorite. Some planes tremble beneath you as though they were alive. Others fly so smoothly that if you felt the slightest tremor, you would have them grounded for safety checks. I have flown at multiples of the speed of sound in perfect comfort and felt sick with fear at 20 feet. How do you pick from such experiences?
Certainly I can rattle off any number of favorite moments. There was the time I flew in the lead plane of the Red Arrows aerobatic display team and had the surreal experience of flying so close beside other planes I felt I could reach out and touch them. There was the time I landed a newly restored Dornier flying boat on Lake Winnebago and discovered that touching down on water feels, for those first few seconds of contact, just like touching down on concrete.
These experiences have taught me something important about the history of flying, and how we should preserve it. Planes are meant to be flown and to be seen flying. Maintaining old planes is expensive, and flying them can be risky. With the best will in the world, it’s not possible to preserve all the skill and knowledge and understanding that went into making them. I believe, however, that if we want to preserve the planes of the past at all, we have to do what we can to preserve them in operating condition. It’s strange to admit it, but I look back with special fondness to the day I was taken up in a Spitfire—strange because I spent most of that flight with my head in a bag.
In 2003, the Discovery Channel organized a series of TV programs and a national poll to celebrate the centenary of powered flight. They got celebrities to act as advocates for their favorite machines, and it was my job to sing the praises of the Spitfire. I had some lines prepared to deliver to the cockpit camera and, in between gagging fits, I delivered them. On the ground again, white, trembling, and thankful to be alive, I found a microphone under my nose: How had I enjoyed my flight? I think the Spitfire won the public poll in spite of my advocacy rather than because of it!
The most remarkable aspect of that flight was the pilot. Spitfires are very much planes in the Wright brothers mold: they are inherently unstable. Fling them around in the air and you have some hope of controlling them. But if you lose your nerve, or drop your speed too far, you can’t expect a Spitfire to stay airborne. It is as thrilling, and as unforgiving, as a sports car.
Planes are only as good as their pilots. This is true even aboard jetliners with onboard flight computers. Those computers carry inside themselves insights from a century of aviation. And that is why, important as the machines are, the history of aviation is really about people. There is nothing we can do to preserve the spirit of the early aviation pioneers, but we can foster it for a new generation. As I’ll explain in a later chapter, I think we foster it rather well. The pioneering spirit of the first exhibition fliers is still with us.
The early 1900s were a special time, of course, and unrepeatable, because no one at that time quite knew how this great new technology would develop. They were years when an aerobatic display thrilled a crowd, demonstrated the abilities of a plane, promoted an airmail service, won a prize, provided footage for a movie, and trained a military pilot—all at the same time! Back then, the magic of flying was concentrated around two or three companies, a handful of people, and a couple of dozen venues, and its achievements and terrors were splashed across every newspaper and newsreel. From the early 1900s to the beginning of the Second World War, the sky offered countless opportunities for everyone—or, anyway, that was the promise. Celebrity, success, wealth, knowledge, the satisfaction of making something new, the chance to see things no one had ever seen before: with these goals before them, the fliers of the golden age came together to create exceptional communities—plane makers and barnstorming troupes, airlines and experimental associations. People lived hard, and frequently died hard. The English motoring pioneer Charles Rolls—who went into partnership with Frederick Royce in 1904 to create one of the world’s great aero-engineering companies—was killed in a flying accident when the tail of his Wright Flyer broke off during a flying display in 1910. At age 32, he was neither the first nor the you
ngest casualty.
Because the Wrights’ machines allowed them to control their flights, they discovered something new each time they rose into the air. They weren’t just testing machines; they were learning how to fly. They learned quickly, too, breaking their own records virtually every time they left the ground. On September 3, 1908, Orville tried out a new Wright plane at Fort Myer, Virginia, for the U.S. Army. He managed one and a half circles of the parade ground and crashed the machine on landing. By September 8 he was flying for ten minutes at a time. The next day, he flew 52 laps in 57 minutes and 30 seconds of unbroken flying time, shattering the record set by his brother in France just four days earlier. So it went on—until, on September 17, as he was flying at 125 feet with the young army officer Tom Selfridge, himself a keen air pioneer, one of the plane’s two propellers split, cutting a guy wire. The plane’s rudder collapsed and the men fell to earth. Selfridge died a few days later of his injuries. Orville would live the rest of his life in pain.
The Wrights’ later careers make for grim reading. Their patents covered virtually every aspect of winged flight, but their very generality made them difficult to defend. The brothers swapped airfields for lawyers’ offices in a losing battle for proprietorship that alienated them from the young generation they inspired. Glenn Curtiss, an indefatigable engineer who would go on to set a world motorcycle speed record of more than 136 miles per hour on a motorcycle of his own invention (it didn’t have any brakes), first met the Wright brothers in 1906. It was they who inspired his interest in aviation. Soon they would be suing him. It was a sour sort of birth for manned flight.
On September 30, 1907, Curtiss became a founding member of the Aerial Experiment Association. Other founders included Alexander Graham Bell, the inventor of the telephone, who described their venture as a “co-operative scientific association, not for gain but for the love of the art and doing what we can to help one another.”