Airships and balloons are known as lighter – than – air aircraft because instead of wings, they use a large envelope or bag full of gas or hot air that is lighter than the air in the atmosphere around it. The air pushes the envelope upwards just as water pushes a submerged air – filled ball up wards. In 1783, the Montgolfier brothers achieved the first manned flight every by sending a hot – air balloon over Paris. Balloons fly where the wind blows them. Airships have engines and can be steered. Today, airships are used for aerial filming and coast – guard patrols and ballooning is a popular sport.
Anatomy of a Modern Airship:
The main part of an airship is its envelope which contains bags of helium gas. The gas is slightly pressurized to keep the envelope in shape. A fin and tail plane keep the airship steady as it flies slowly along. The crew travels in a gondola attached to the underside of the envelope.
Types of Airship:
Practical airships could be built only after the lightweight internal combustion engine had been developed. The earliest airships were rigid and the less usual semi rigid types of airship.
Several terrible disasters made people lost trust in airship travel. Airships were usually lost for two reasons. Either they were uncontrollable in bad weather. Or the highly inflammable hydrogen gas used inside the envelope exploded. Today, airship pilots use the much safer helium gas in special nylon envelopes. However, they still have to be wary of the weather.
Ferdinand von Zeppelin:
German count Ferdinand von Zeppelin (1838 – 1917) began experimenting with air travel in 1891. In 1900, he devised the first airship, a 128 m (420 ft) rigid craft named the LZI. During World War I, some 100 Zeppelins were built for military use.
Hot – air ballooning requires a perfectly clear day with a gentle breeze. Too high a wind puts the balloon at risk on take – off and landing. After take off, a ground crew follows the balloon in a vehicle to recover both it and the crew after landing.
Balloons were first used for aerial reconnaissance during the French Revolution and used again in the American Civil War. During World Wars I and II, balloons were used to spot targets for artillery attacks and barrage balloons defended cities against aircraft.
Weather and Research Balloons:
To study what is happening in the upper reaches of the atmosphere, pilots send up helium – filled weather balloons. They carry instruments which measure temperature, wind, speed and so on and send their results to the ground or to satellites by radio.
Today, ballooning is a popular sport. During the summer, ballooning enthusiasts gather at festivals to enjoy the dazzling prospect of dozens of brightly colored balloons flying together. Some of the balloons are owned by companies and are made in the shapes of their produce as a form of adverting. Airships and Balloons are known as lighter – than – air aircraft. Airships and Balloons are used today in various occassions.