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Theory of Flight

The subject is Aerodynamics or Theory of Flight.

The word Aerodynamics comes from two root words, aeros and dynamic. Aeros simply means air while dynamic means motion. Therefore the study of aerodynamics is the study of air in motion. By the way, there is another subject called aerostatics, which is the study of air that is not in motion (static meaning: not in motion.) Aerostatics explains things like hot-air balloons and dirigibles.

For my YouTube video series I chose the title "Theory of Flight" because I wanted to emphasize two distinct but important topics. Of course one of those topics is flight. I am fist and last a pilot. I love aeroplanes (that's airplane for any americans reading this.) Like all pilots I love to fly, and like many I like to think about how we defy gravity and float above the rest of humanity dancing with the clouds.

But, I also wanted to emphasize the meaning of the word theory, as it is used by scientists. In between flights I fancy myself a philosopher and one of the particular aspects of philosophy that gets me excited is epistemology, which is the study of how we (humans that is) know things. For most people in everyday life to "know something" is just to be certain of it. That is to say to really, really, really believe it. But to a philosopher that is not enough. After all, people were certain for millennia that the sun moved across the sky each day. A mere 450 years ago, in the middle of the 16th century, a guy called Copernicus suggested that this was an illusion. The sun isn't really moving across the sky, he said. The sky is moving across the sun. He was so "crazy" that he actually believed the earth was rotating on an axis. The belief that the earth rotates was a theory when Copernicus suggested it, and it is still a theory today. The only difference is that today people don't laugh at it, they mostly believe it to be true. But why? How did science, which did not exist in the 16th century, come about and eventually convince us all to believe that the earth is rotating and consequently the sun is not actually moving across the sky.

if you were transported back in time to the 16th century do you think you could convince the people from that time that the earth is rotating?

In this video I discuss what a theory is and how the power of logic is used in science to invalidate theories that are not true. I then give an example of a common theory that many pilots believe, namely that an airplane rolls because one wing produces more lift that the other. This is a false theory, easily disproved with a simple logical analysis, and yet it persists.

 

 

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Otto Lilienthal was a leading researcher in flight in the last decade of the 19th century. He was an inspiration to the Wright Brothers. Unfortunately he died in a crash of one of his gliders, shown here, in 1896. Had he not died many people speculate that he would have been the first to achieve powered flight. But that may be overly generous given that his gliders lacked the sophisticated control system the Wright Brothers developed.

It was undoubtedly Lilenthal's death that convinced the Wright Brothers that it was not wise to attempt powered flight until they had mastered the question of control. It was their mastery of control that allowed them to succeed where so many others failed.

Lilenthal's glider

The photo to the right shows a recreation of one of the Wright brothers gliders used in 1902 to obtain aerodynamic data and develop pilot skills prior to the 1903 first powered flight.

 

Wright Glider

To the right is a recreation of the wind tunnel Orville and Wilbur made to test their aerodynamic theories.

The brothers discovered that most of what was written about aerodynamics at the time was wrong. Their pain staking scientific approach explains why they succeeded when so may others were trying, and failing, to fly.

Wright Wind Tunnel

Octave Chanute, shown in recreation to the right, was one of the few early pioneers not obsessed with competitiveness and secrecy. He openly shared his advice and encouragement with the Wright Brothers.

This is one of Chanutes gliders from the late 1890s.

Octave Chanute

Video Lectures

Aerodynamic Simulations

Other Aerodynamic Resources

Aerodynamics on the Web

 

 

© Copyright Raymond J. Preston