Monday, January 22, 2007

Welcome to Aviation Week

The dreams of aviation date back many millennia and there is an abundance of traditional myths that deal with the idea of humans flying like birds. One of the most well known stories is of course the Greek tale where Icarus and his father escape from their imprisonment on Crete by fabricating wings from feathers. Unfortunately, Icarus flies to close to the sun and ruins his wings. Without his wings, he is of course unable to fly and he drowns in the Mediterranean Sea. The true history of aviation is also filled with such tragedies; but it is also an example of human perseverance and our ability to invent incredible things and make our dreams come true.

Air crafts are usually divided into two main categories: crafts that are lighter than air and crafts that are heavier than air. In the first category you will find aircrafts such as hot air balloons and airships. These aircrafts ascend since they contain a gas that has a lower density than air. This phenomenon is caused by the same natural force that makes it possible for boats to float on water: buoyancy. The first aircrafts used heated air to fly, and heated air is still a common medium in air balloons. Warm air has a lower density than cold air, and the hot air inside the balloon will therefore rise. Later, other gases such as helium and hydrogen became popular but a problem with them is that they are highly combustible.

The first known hot air balloon was created in France in 1783 by the Montgolfier brothers. Their father was a paper manufacturer and when they brother were young they liked to play with inverted paper bags over open fire. In 1782 they managed to launch an 18 m³ silk bag that rose to an altitude of 250 meters. The brothers were encouraged by their success and the following year they sent up a 900 m³ linen bag during a public demonstration. This balloon flew for more than 10 minutes and covered a distance of 2 kilometres. Estimations show that it probably reached an altitude of 1600 meters or more. The brothers carried on with their experiments and sent up a duck, a cockerel and a sheep named Montauciel in a basket that was attached to a large balloon. The name Montauciel actually means “climb to the sky”. This experiment was carried out before Louis XVI of France, since the brothers needed his permission before they could begin to send up humans in balloons. A tear actually occurred in the balloon during this experiment, but the balloon landed safely and no animals were hurt. In November 1783, the Montgolfier brothers sent up Marquis D'Arlandes and a physics teacher named Pilâtre de Rozier. They sailed from château La Muette to the Butte aux Cailles outside Paris in a hot air balloon that; a 9 kilometer long trip that took 25 minutes. Their balloon reached an altitude of approximately 10,000 meters and the experiment gained a lot of public attention.

Air crafts that are heavier than air will not ascend like balloons and airships; they need engines to provide them with enough force. In this group you will find traditional airplanes as well as helicopters and autogyros. Airplanes are fixed-winged aircrafts and usually be equipped with a turbine engine or an internal-combustion engine. The so called gliders do however not have any engine; they relay on rising air masses to keep them off the ground. Rising air masses are constantly created by a wide range of natural weather phenomena, including thermals, ridge lift, mountain wave, convergence, morning glory and polar vortexes.

All air crafts need to be stored, much like a car or truck do. Many manufacturers build customized hangars and other metal buildings to house air crafts and keep them out of the elements.

The history of the gliders is often overlooked since motorized airplanes are much more common in our modern lives. The Wright Brothers, Percy Pilcher, Otto Lilienthal and John J Montgomery were however all devoted glider constructors and gliders are the source of modern motorized airplanes. The history of the gliders dates back to ancient China where kites large enough to carry military reconnaissance personal were developed. The first known glider was created in 500 BC by a man named Lu Pan, but his type of glider was used for recreation rather than military purposes. According to some sources, gliders were used in China as early as 500 AD but these claims have not been verified. The first European glider that could carry a person was created much later, in 1853. This glider was designed by Sir George Cayley, an English baronet and inventor. He had constructed model gliders as early as 1804, but it wasn’t until the middle of the century that he built a glider large enough to carry a pilot and convinced his coachman to fly it. Before the coachman tried the glider, Cayley demonstrated how safe it was by letting animals fly around in it. Cayley and his coachman launched the glider from a hill on the Brompton Estate and the coachman managed to pilot the glider all the way across the Brompton Dale. After a 130 meter long flight, he landed on a meadow, thereby completing the first European flight in a heavier-than-air craft.