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For the pioneers of human aviation, one of the trickiest problems was figuring out how to steer the early craft. Then, the Wright Brothers changed everything by using bike parts and watching birds.

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At some point in a history class, you probably learned that Orville and Wilbur Wright invented the airplane in 1903. And you probably forgot the date, but you remembered those names!

Or maybe you’ve seen a North Carolina license plate proclaiming that their state was “first in flight,” since that’s where the Wright Flyer took off. But… it probably won’t shock you to learn that the story of flight is just a tad bit more complicated than that. After all, humans have been thinking about flying for thousands of years.

It’s not really a surprise that no one pair of brothers can claim all the credit for getting us airborne…. So, let’s take a look at some of the milestones leading up to that famous flight at Kitty. Hawk, as well as what was remarkable about how Orville and Wilbur put it all together.

Now, the first human flight technically happened in 1783, when the first hot air balloon went up in France and carried men about nine kilometers. Brave guys, those. They’re just like “Let’s go up!

See what happens!” But leading up to the turn of the 20th century, the pioneers of human flight had a more specific goal. They wanted to design a vehicle that met five criteria:. First, it had to be heavier than air—so, not a blimp or hot air balloon.

And it needed to be powered, meaning it couldn’t just be a glider carried by the wind. Beyond that, it needed to be steerable, carry a pilot, and sustain flight for some time. The Wright brothers’ 1903 plane had all that—but they weren’t actually the first aviators to reach any of those individual milestones.

Long before the Wright brothers entered the scene, others had made lots of good progress. Like, the British inventor George Cayley built the first successful, heavier-than-air glider in 1804, and 45 years later, he even succeeded in building a craft that could carry a pilot. In 1890, the French inventor Clément Ader took off in a powered plane, but it crashed after about 50 meters.

And when the American scientist Samuel Langley finally achieved powered and sustained flight just a few years later, it was in a plane without a pilot. That left steering, which was an ongoing struggle, but in the 1890s, the German aviator Otto. Lilienthal had had some success in controlling a glider by shifting his weight.

So at the turn of the century, the technology was close. All five elements of modern flight had been demonstrated one way or another. And yet, no true airplane had been built.

There were two big obstacles to putting all this technology together and building a machine that checked all the boxes: producing enough power to carry a piloted aircraft… and steering. Of the five criteria for a successful plane, steering was maybe the most challenging one to master. And that’s where the Wright brothers came in.

The brothers were the owners of a bike shop in Dayton, Ohio, and they became interested in aviation in the late 1800s. Their first, and probably most important, technical achievement was to develop an improved control scheme. Because unfortunately, Otto Lilienthal’s weight-shifting approach wasn’t an end-all solution.

To steer his gliders, he would move his legs from side to side to change the gliders’ center of gravity. And you have to hand it to him—he did manage to make more than 2000 successful flights that way. But leg-shifting… isn’t exactly scalable to larger aircraft.

So the Wright brothers wanted to figure out a better technique. They knew that, unlike a car, aircraft don’t turn by rotating left or right. Instead, they primarily change direction by tilting, which is known in aviation as a roll.

Birds turn by rolling too, and by studying them, Wilbur noticed that they seemed to enter a roll by turning one wing tip up and the other down. These observations helped him realize that the key to rolling a plane is to make opposite movements on each wing. That’s because wings depend on a force called lift to support an object in the air.

Lift comes straight out of Newton’s famous third law, which says that every action has an equal and opposite reaction. When flying straight, the wings of the Wright Flyer were tipped back a little bit. That way, when moving air hit them, it would be deflected downwards.

And the opposite of deflecting the air down is lifting the plane up. But the amount of lift a wing can generate depends on what’s called the angle of attack—that’s the angle between the wing and the flow of air. If the two sides of the plane had different angles of attack, they’d generate different amounts of lift, and the uneven forces would tip the plane to one side.

Then, instead of deflecting the moving air straight down, the wing would also push some air to the side, which would move the plane in the opposite direction. To put this into practice, the Wrights built a biplane, an aircraft with two sets of wings stacked one above the other. The wings were flexible, and the brothers attached cables to the tips of each wing that were connected to pedals used by the pilot.

Pushing down on a pedal would shorten the cables on one side and lengthen them on the other. As the cables lengthened or loosened, the wings would twist, which changed the angle each one made with the air. That took care of roll, which is the main way planes change orientation, but there are still two other ways:.

The nose can tilt up or down, which is known as pitch, and move left to right, which is known as yaw. To give themselves control over pitch, the Wright brothers mounted a pair of horizontal flaps on the front of the plane called the elevators. These were miniature versions of the wings.

If they were tilted up, they added to the plane’s overall lift. If they were tilted down, they counteracted the lift of the main wings. But since they were mounted in front of the aircraft’s center of mass, this small force acted kind of like a lever that could tilt the plane up or down.

As for yaw, the brothers added two vertical flaps called rudders to the back of the plane that worked a lot like a rudder in a boat: When turned to one side, they would deflect air as it moved past the plane, nudging the nose in the opposite direction. Now, if it seems like rudders make rolling the plane a little obsolete, that’s a fair thought. Because yaw does turn the plane.

But it’s also a lot less efficient than rolling the wings, which are much bigger and exert more force on the aircraft. Rudders are still important, though: They keep the plane stable during a roll. (And stability is important if you want to land.) So, at this point, with control over the pitch, yaw, and roll, the Wright Flyer was the first aircraft capable of changing its orientation along any direction. This was the fundamental breakthrough needed for reliable, controllable flight.

And although modern planes no longer warp their wings, they still use the concept of asymmetrical lift to make a plane roll. And the elevator and rudder are critical for stable flight, too. But to really take to the skies, that wasn’t all we needed.

We also needed some good propulsion. And that’s where the Wrights’ second breakthrough came in. To power their plane, they chose a promising new technology: the internal combustion engine.

Unfortunately, they couldn’t pull one of these out of a car and slap it on their plane. The engines being mass-produced for automobiles were still too heavy to be useful for flight. So, the brothers built their own engine with the help of a local mechanic.

To reduce its weight, they cast pieces of the engine out of aluminum, which is much lighter than other metals, like iron or steel. I mean, even so, their engine still weighed 80 kilograms. And it produced only about twice as much power as an average, modern lawnmower—but hey, it was enough.

To make use of their limited power, the Wrights needed a very efficient propeller. At the time, most aircraft propeller designs were based on those of ships or windmills… but neither one was really ideal for the physics of flight. Propellers on boats have short blades, because those work best for traveling through water.

And old-timey windmills are built to move slowly since wind isn’t usually very fast. But the best bet for an airplane was a propeller with long, fast-moving blades. And here’s where the brothers had a great insight: they thought of the propeller as basically a sideways wing.

Instead of producing lift to keep the plane up, it produced thrust to drive it forward, but the physics was almost exactly the same. To build their propeller, they hand-carved long, thin blades out of wood and connected them to the engine so that they would rotate quickly, about 350 times a minute. These blades would do the trick—but remember Newton’s third law: If the engine is spinning the propeller quickly in one direction, that means it’s also trying to spin the plane in the opposite direction.

And since early planes were very light, this had the potential to really mess things up. So to cancel out this twisting effect, the brothers set the plane up with two propellers spinning in opposite directions. The amount of thrust each one produced would be pretty pitiful for a modern plane, but it was enough for them.

In fact, modern computer simulations show that the brothers’ blade design was nearly perfect for the slow speeds the Wright Flyer would travel at. Finally, the Wrights’ third big breakthrough was how they put all the pieces together. It’s hard to overstate how dangerous early experiments in flight were.

Early inventors died all the time. Even Otto Lilienthal, the first person to build a reliably controllable glider, eventually died because of a crash. But the Wrights were determined to live long enough to see their project through, so they rigorously tested and refined each piece of their plane.

And along the way, they helped pioneer the modern process of engineering design. One of their key tools was the wind tunnel. After early tests in 1900 and 1901, the Wrights found that their gliders weren’t performing as well as they expected.

They’d been using a data table compiled by Lilienthal that spelled out the amount of lift and drag, or air resistance, a given wing shape would produce at different angles of attack. But when their experiments fell short of their predictions, they began to suspect that Lilienthal’s values were wrong. So, they built their own wind tunnel to make better calculations.

A wind tunnel is basically just a tube with a fan on one end to create a smooth flow of air. And the Wright brothers were not the first to use one, but they took the practice to a whole new level. They constructed delicate instruments capable of precisely measuring the amount of lift and drag generated by an attached wing.

Ultimately, they tested around 200 wing designs and made detailed measurements for nearly 50. These measurements were so precise that the brothers were able to correct a key constant in the equations of flight that had been used since the 1700s—including in Lilienthal’s data tables. And we now know that the value they used while building the Wright Flyer was just a few percent off from the modern value.

Orville and Wilbur also made extensive use of kites, building smaller versions of their gliders to test their stability before scaling up to a full-size glider and then finally a powered airplane. At each step, the brothers tested their design as exhaustively and as safely as possible. And you know what?

It worked. Not only did they build the first aircraft to satisfy all five key elements of flight, they lived to tell the tale and even took photographs to prove their claim. The Wright Flyer was a textbook example of how engineering happens.

The brothers’ success built on more than a century of work, refining and combining others’ ideas in useful ways. They also made key breakthroughs that enabled them to solve the problems that had limited past efforts. And it all happened through rigorous cycles of design, testing, and evaluation, with safety as a priority.

So there are good reasons why Orville and Wilbur are still so famous today—but while they might have built the first airplane, they definitely didn’t do it alone. Thanks for watching this episode of SciShow! And a special thanks to everyone who supports us, like those of you who have joined us as.

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