75 Up in the Air Our Fight Against Gravity

CHAPTER 1 Gravity THE FORCE OF GRAVITY IS STOPPING YOU FROM FLOATING AWAY INTO THE AIR RIGHT NOW! Gravity is all about attraction. Sometimes called "the law of attraction," gravity was discovered in the 17th century. Although scientists' understanding of gravity has become richer since then, the basic idea is still the same: the bigger the object, the more the objects around it are attracted to it. This means, for example, that our planet Earth is held in place by its attraction to the much larger Sun. Gravity gives us weight and keeps our feet on the ground. For humans, the strength of gravity on Earth means that we can walk, run, or jump, but we cannot fly. And yet, perhaps because of the beauty of flying birds, or perhaps because of our curiosity about the Sun, the Moon, and the stars, humans have often looked up into the sky and dreamed of flying.

By watching how birds fly and trying to copy them, scientists gradually learned about the physics of flying. One of the earliest thinkers to look seriously at flying was the 15th-century Italian artist and scientist Leonardo Da Vinci. Da Vinci made drawings for three different types of flying machines. One was similar to a modern glider, another worked like a helicopter, and the third was a type of parachute. Although Da Vinci's inventions were never built in his lifetime, we now know that at least one of his designs works. In 2000, Da Vinci's parachute design was built and tested by an expert parachute jumper, Adrian Nicholas. Nicholas made a jump from 3,000 meters and landed perfectly. He even found that the parachute made from Da Vinci's design flew more smoothly than a modern parachute!

A big problem for designing flying machines was finding out how to lift them into the air. Many of the first ideas were based on birds, with machines that used moving wings to try to take off! Birds' bodies, however, are light and their wings are strong, so it was impossible to make a machine that flew like a bird. But there was another way to create lift. The idea of filling a bag with hot air had been used by the Chinese for centuries for sending messages. In the 18th century, Europeans began to experiment with balloons for carrying people. In 1783, in France, the Montgolfier brothers made the first successful hot air balloon for passengers. It worked by heating the air inside a paper and silk balloon. The brothers, however, were not sure that flying was safe for people, so the passengers in the first flight were animals: a sheep, a duck, and a rooster. Unlike lighter-than-air balloons, machines still had the problem of getting off the ground. Steam engines were just too heavy. But in 1885 Karl Benz gave aircraft designers new hope.

His invention, the gasoline engine, was light enough to fly. A few gas-powered planes were built. Unfortunately, all of them crashed. Now the problem was that they were too difficult to control. It took two bicycle mechanics from Ohio, USA, to solve the problem. Brothers Wilbur and Orville Wright had been fascinated by flying machines for years. They used their skills as mechanics to make and fly gliders. This allowed them to perfect the controls a pilot needs to fly a plane. They added an engine to their glider to create the Wright Flyer 1. On December 17, 1903, they made the first successful powered flight and changed history forever.

CHAPTER 2 Air Transportation THE 20TH CENTURY MAY WELL BE LOOKED BACK ON AS THE AGE OF FLIGHT. After the Wright brothers' invention in 1903, the airplane quickly developed into an important means of transport and communication, changing the way we experience and see our world. Helicopters, balloons, and parachutes, and later the development of space rockets, also took flying to new heights. The airplane, however, is probably the first thing that comes to mind when you think about flying. In the last 50 years, airplanes have become the usual way to travel long distances. The first airplanes, however, were used more to carry objects, not passengers. One of the first uses for planes was the US airmail service, carrying letters and parcels across the United States.

In 1914, the first commercial passenger flight took place in the USA. Only one passenger bought a seat! By 1919, there were international passenger flights between London and Paris. Long distance international passenger services didn't become common until after World War II. In 1952, the first jet plane for passengers, the de Havilland 106, flew from London to Johannesburg, South Africa. It carried just 36 passengers and took 24 hours to complete the journey, stopping five times on the way. The first transatlantic jet service between London and New York started in 1958. It took just over ten hours. Over the next decade, jet planes got bigger and faster. One of the most popular was the Boeing 747. First introduced in 1968 and still in use today, the 747 can carry as many as 600 passengers!