The act of passing through the air by the use of wings.
Humans have dreamed about flying for thousands of years. They probably watched birds, insects, bats, or leaves and imagined and wondered what it must be like.
However, it took many years for humans to understand the properties of earth and air necessary for flight and be able to measure them accurately, develop relevant theories, and predict outcomes. Only then could people build the wings and engines needed to fly.
A Short History of Flight
Around 350 BC the Chinese began to make kites from bamboo frames covered in paper and silk. Many of today's kites use a similar design. A kite is a form of a glider, as it does not technically fly, but instead sails on air currents.
In 1492 the Italian scientist, artist, and inventor Leonardo da Vinci observed the flight of birds and analyzed their anatomy. He designed parachutes, helicopters, and flying machines that looked quite like the early attempts at making flying machines in the 1900's.
In 1670 another Italian scientist, Giovanni Borelli, who studied the mechanics of animal movement, proved that human muscles wouldn't be strong enough to hold the big wings needed to lift a human off the ground.
In June 1783 two French brothers, Joseph and Jacques Montgolfier, who owned a paper mill, inflated a balloon with hot air. They had observed that hot air rises and decided to see if they could create a craft based on this newly discovered science. Their unmanned balloon rose into the sky. This led to additional attempts at flight.
On September 19, 1783, three passengers along with a sheep, a rooster, and a duck were successfully launched into the air in a hot air balloon. The Montgolfier brothers continued to play with balloon flight, and soon others were experimenting with this type of craft.
Many additional attempts in flight were made over the next 120 years — mostly glider crafts. However, it was the brothers Wilbur and Orville Wright who, in 1903, for the first time ". . . in the history of the world . . . [created] a machine carrying a man . . . [which] raised itself by its own power into the air in full flight, . . . sailed forward without reduction of speed and . . . finally landed at a point as high as that from which it started."
You can view sample pages from the Wright Brothers' notebooks at the Franklin Institute's Flight pages.
And you can learn more about the Wright Brothers' experiments and view some aeronautical simulations at the Open University's First Flight website..
In the 1920s and 1930s, a craft known as a dirigible became a common mode of transportation for intercontinental travel. A dirigible was a frame covered with fabric and filled with a gas. The craft could be steered, which made it different from a hot air balloon. Learn more about dirigibles at the Centennial of Flight website.
Blimps and zeppelins are kinds of dirigibles. The most famous of these is probably the Hindenburg, which during its landing on May 6, 1937, burst into flames and crashed, killing 35 persons on the airship and one member of the ground crew. Another famous dirigible is the Goodyear Blimp, which can be seen hovering above many sporting events.
Air travel is now very common, with thousands of airplane flights worldwide every day. Commercial planes, private aircraft, and space travel would not be possible without the pioneers of flight.
Two Kinds of Flight: Gliding and True
Gliding flight is accomplished with little or no movement or flapping of wings. Leaves, maple seeds, or dandelion seeds seem to float with the wind, but they aren't true flyers.
Man has built gliders which have no engines but are towed into the air by an airplane. It can take hours for a glider to return to Earth. A number of animals use this method of movement but do not actually "fly." Flying squirrels, flying fish, and some snakes have skin that they can stretch out and use to glide through the air.
True flight is accomplished only by birds, insects, and bats. Wings allow these creatures to push on the air to give them lift, thus allowing them to get airborne. Other bodily structures such as muscles and bones provide additional support for flight.
Some birds, in addition to flying, will actually seek out warm updrafts of air known as thermals which travel up from the ground. The birds will glide on these thermals, sailing around in circles or hovering in place.
What is Flight?
There are 4 aerodynamic forces which are present when air is moving past an object. Weight, lift, drag, and thrust must all be understood before anyone can design an aircraft. The study of these forces as they relate to flight is the science of aeronautics.
Weight is caused by the pull of Earth's gravity on our body. A flying object must overcome this force.
Lift is the upward force that works against gravity and weight.
Thrust is the forward push made when an engine turns a propeller. The propeller is shaped to push the air backwards. This results in a reaction force (thrust) on the propeller that moves the aircraft forwards.
Drag, or air resistance slows down the forward movement of an aircraft. It is caused by friction between the moving object and the air around it.
Learn more about these four forces at NASA's Dynamics of Flight website.
Top 10 Questions
Thanks to Frank Lester, education coordinator of the Aeronautics Division, Idaho Transportation Department; and Lori MacNichol-Gregory, pilot and certified flight instructor, McCall Mountain/Canyon Flying Semin for the answers.
Why does a bird have to flap its wings to take off?
Birds don't have an engine. So, they need their wings to create both lift and thrust. They flap their long, long wings and this creates a pressure underneath. This pressure is the thrust and lift factor lifting the bird into the air and moving them forward. (From Jacob in Mrs. Woodall's class at Dalton Elementary School in Dalton Gardens)
Why can't a plane fly into space?
A plane can't fly into space because there is no air. Planes use their wings with air to give them lift. In space, there is no air to produce lift, so you have to have excessive amounts of thrust. Thrust is produced by engines once outside the atmosphere. It's the thrust that keeps a craft airborne. (From Katie in Mrs. Hudson's class at Dalton Elementary School in Dalton Gardens)
What causes a sonic boom?
When an aircraft goes beyond the speed of sound, we hear a big boom. It actually goes through a sound barrier and makes a big, loud boom. The speed of sound is around 760 miles an hour. (From Morgan in Mrs. Woodall's class at Dalton Elementary School in Dalton Gardens)
Will science ever be good enough to make flying cars?
It is! They are making them now! The first flying car was invented back in the 50's and was called the "aerocar." Today, they are pretty successful in getting up in the air and landing. However, they do need to make some changes in order to get certified by the FAA and meet auto standards for the road. (From Lily in Mrs. Hudson's class at Dalton Elementary School in Dalton Gardens)
How do heavy airplanes fly in mid-air?
The heaviest airplane in the world is around one million pounds. Heavier airplanes need larger wings because they need more surface area to generate the lift, and they need larger engines to generate the thrust. (From Braelynn in Mrs. Schweitzer's class at Riverside Elementary School in Boise)
When did the Wright brothers fly their first aircraft?
Their first powered flight was December 17, 1903. They were probably flying gliders several years before that. (From Ryan in Mrs. Schweitzer's class at Riverside Elementary School in Boise)
What is a thermal made of?
A thermal is a lifting of air. It can be created by many different things. One of the most common things would be the sun shining on a surface. This creates heat and transpires into a type of thermal or lifting of air. The air rises because as you heat something, the air expands. (From Colton in Mrs. Woodall's class at Dalton Elementary School in Dalton Gardens)
What is the most efficient and least expensive way to become a pilot?
It depends on how much time you can devote to it. Your chances of completing your certificate are much greater if you can devote one full month to learning how to fly versus spreading it out over a year. Set aside the right amount of time and then that will help reduce the cost somewhat. (From Keegan in Meridian)
What does it look like flying a plane?
It's just amazing. You take off and watch the airport, neighborhoods and trees getting smaller. It's wonderful to experience the three axes of flight; pitch, roll and yaw. When you are in a car you have two axes, but when you fly, you are working in three dimensions. (From Gabe in Mrs. Hunt's class at Cynthia Mann Elementary School in Boise)
How is thrust made?
It's basically the air being forced behind the aircraft and this pushes the craft forward. A single engine airplane has a propeller that rotates, creating lift in the horizontal. We call this thrust. A jet engine takes the air and sucks it into the engine squeezing it down. As the air is squeezed, it heats up. Fuel is then pumped into the engine and an explosion occurs forcing the air out the back of the engine. This creates the thrust that pushes the plane forward. (From Jacob in Mrs. Woodall's class at Dalton Elementary School in Dalton Gardens)