What makes flight possible

Why do trees sway in the wind? Why does wind happen, even? The answer to all these questions is: forces. Engineers use physics to study forces, and then apply what they learn about forces to solve problems.

Forces can make things speed up, and balanced forces can make things stay still or move at a constant speed. In this lesson, we will learn about forces by examining airplanes and parachutes. We will learn that more than one force acts on things that fly, and we will see what we can do to change forces.

In other words, we'll learn why airplanes can fly! Refer to the associated activities Heavy Helicopters and Blow-and-Go Parachute to help illustrate how these forces affect air craft flight! After a winter of experimenting with an air tunnel an enclosed space with a stationery object surrounded by moving air to learn more about the forces of flight, Wilbur and Orville Wright flew the first airplane that could be controlled in the air in Today, more than 4, public airports in the U.

People ride in hot-air balloons and jump out of airplanes with parachutes for fun, trusting that a balance of forces will keep them from hitting the ground too hard.

An understanding of forces allows aeronautical engineers to design all the different kinds of airplanes, hot-air balloons, and parachutes that have ever flown! Following the lesson refer to the associated activity You Are There First Flight for students to learn the value of historical documents and eyewitness accounts, and recreate the Wright Brothers' first flight in the style of the "You Are There" television show.

Aerodynamics, the study of flight, is founded on four basic forces — lift, weight, thrust and drag. The interaction of these forces explains the movement of objects as they soar through the sky.

What seems like magic — a several ton object flying, like an airplane flying through the sky! Diagram of an airliner showing vectors for lift, thrust, drag and weight. The first force, lift , pushes up on things that fly — airplanes, birds, helicopters and rockets. The shape of the wings on an airplane and the whirling blades of a helicopter create lift as they move through the air.

The second force is weight — the force of two masses being attracted to each other. Weight is the force that pulls us towards the center of the earth, and why things fall down. The third force is thrust. Thrust is created by the jet engines or propellers of an airplane. Birds create thrust and lift! Thrust pushes things that are flying. The fourth force is drag. Drag pushes against things moving through the air. It is caused by air particles bumping into the object.

An object that is going faster bumps into more air particles, and so experiences more drag. Similarly, an object with a large surface area bumps into more particles, and experiences more drag. When the forces are not balanced, flying objects speed up, slow down or change direction. This is called acceleration. For example, when the thrust force is bigger than the drag force, an airplane speeds up.

When the lift force is bigger than the weight force, the airplane goes up faster. When forces are balanced, objects do not accelerate. An airplane that is flying in a straight line at a certain speed has balanced forces.

An airplane can even be going up or down and have balanced forces. As long as the airplane is not turning, speeding up or slowing down in any direction, even up and down! Sometimes, two of the forces may be the same thing. For example, a rocket engine pushes a rocket straight up, providing both lift and thrust.

The earliest flying machines were kites, invented thousands of years ago in Asia. In the s, Leonardo da Vinci applied his artistic and engineering genius to the mystery of flight. His ornithopter invention allowed the pilot-passenger to flap giant wings like a bird, and his helicopter-type invention featured a screw-shaped sail.

His machines, however, were never built. In , the first passengers in their colorful balloon were a sheep, rooster and duck. The first people took flight on November 21, Starting in and continuing for 50 years, English engineer George Cayley designed many different gliders. He changed the shape of the wings to experiment with the way the air flows over the wings. He also designed a tail to help with stability, and tried a biplane design to add strength.

Based on his experiments, he was the one who identified the four forces—weight, lift, drag, and thrust—which are in effect on any flying machine. His gliders were also the first to successfully carry a person into the sky! In his book On Aerial Navigation , Cayley hypothesized that a fixed-wing aircraft, with a power system for propulsion and a tail to assist in the control of the airplane, would be the best way to allow people to fly.

Several other inventors continued to improve the glider design and experiment with adding power to their prototypes, including Otto Lilienthal and Samuel P. Langley, both with notable achievements in Brothers Orville and Wilbur Wright are celebrated as the first to create a powered flying machine that could carry a person.

After a great deal of research and experiments with kites, they spent a lot of time testing different glider shapes and learning about how gliders could be controlled. Once they found a successful glider shape, they turned their attention to how to create a propulsion system that would create the lift needed to fly.

Orville piloted the plane, which weighed kilograms. Anderson, Jr. What Anderson said, however, is that there is actually no agreement on what generates the aerodynamic force known as lift. At this point in the history of flight, this situation is slightly puzzling. After all, the natural processes of evolution, working mindlessly, at random and without any understanding of physics, solved the mechanical problem of aerodynamic lift for soaring birds eons ago.

Why should it be so hard for scientists to explain what keeps birds, and airliners, up in the air? Adding to the confusion is the fact that accounts of lift exist on two separate levels of abstraction: the technical and the nontechnical. They are complementary rather than contradictory, but they differ in their aims. One exists as a strictly mathematical theory, a realm in which the analysis medium consists of equations, symbols, computer simulations and numbers.

There is little, if any, serious disagreement as to what the appropriate equations or their solutions are. The objective of technical mathematical theory is to make accurate predictions and to project results that are useful to aeronautical engineers engaged in the complex business of designing aircraft.

But by themselves, equations are not explanations, and neither are their solutions. There is a second, nontechnical level of analysis that is intended to provide us with a physical, commonsense explanation of lift. The objective of the nontechnical approach is to give us an intuitive understanding of the actual forces and factors that are at work in holding an airplane aloft. This approach exists not on the level of numbers and equations but rather on the level of concepts and principles that are familiar and intelligible to nonspecialists.

It is on this second, nontechnical level where the controversies lie. Two different theories are commonly proposed to explain lift, and advocates on both sides argue their viewpoints in articles, in books and online. The problem is that each of these two nontechnical theories is correct in itself. But neither produces a complete explanation of lift, one that provides a full accounting of all the basic forces, factors and physical conditions governing aerodynamic lift, with no issues left dangling, unexplained or unknown.

Does such a theory even exist? Bernoulli came from a family of mathematicians. In other words, the theorem does not say how the higher velocity above the wing came about to begin with. There are plenty of bad explanations for the higher velocity. Because the top parcel travels farther than the lower parcel in a given amount of time, it must go faster. The fallacy here is that there is no physical reason that the two parcels must reach the trailing edge simultaneously.

And indeed, they do not: the empirical fact is that the air atop moves much faster than the equal transit time theory could account for. It involves holding a sheet of paper horizontally at your mouth and blowing across the curved top of it. The page rises, supposedly illustrating the Bernoulli effect. The opposite result ought to occur when you blow across the bottom of the sheet: the velocity of the moving air below it should pull the page downward.

Instead, paradoxically, the page rises. You will feel the effect of this force if you jump up from the floor. Your weight will force you back down. When the Thrust produced by the engine s is greater than the force of Drag , the airplane moves forward.

When the forward motion is enough to produce a force of Lift that is greater than the Weight , the airplane moves upward. Governor Ned Lamont. Home About Us Contact Us. State Symbols. While any part of the airplane can produce Lift , the most Lift comes from the wings. Fixed and Rotary Wing Aircraft.

Now you are probably thinking that helicopters do not need to move forward in order to fly, and you are right.