Warmatrix

An airship or dirigible is an aerostat, an aircraft that uses gas or hot air to become lighter than normal air and generate lift.
The first balloon capable of carrying passengers was the hot air balloon built by the Montgolfier brothers in 1783 CE. Two years later Jean-Pierre Blanchard fitted a hand-powered propeller to a balloon and crossed the English Channel with it, but reliable propulsion proved difficult to achieve with 18th century CE technology. Balloons were occasionally used in war as observation and signaling platforms. The first true airship, capable of a controlled flight, was the La France, built in 1884 CE. It could achieve a speed of 24 kilometers per hour.
Airships can be rigid, built around a frame; semi-rigid, with a flexible structure or non-rigid, without any support. The latter category is also called blimps. Early balloons and airships were filled with hot air, but the constant need to re-heat that prohibits long flights. Hot air was quickly joined by hydrogen gas, which generates maximum lift. Most airships attach engines to their gondolas for propulsion and steering. The first engines were steam powered; later gasoline and electric engines took over. Airships have little trouble remaining aloft for a long time, though maximum speed is limited to about 150 kilometers per hour even with modern engines.
In 1900 CE Count von Zeppelin launched the Zeppelin LZ 1. This was the start of a long line of airships that gave Germany a lead in their development. Many German military thinkers believed that airship bombers would give Germany an advantage to counter British naval superiority at sea. During World War I the Zeppelins proved almost immune to defensive anti aircraft fire, but low speed, limited range and carrying capacity, frequent mechanical failures and inaccurate bombing made them equally useless as attackers. In 1916 CE the defenders started shooting with incendiary and explosive ammunition that could set the hydrogen gas aflame. At the same time the range of airplanes improved. These factors spelled the end of the floating bombers and most other military airships. Some airships and balloons remained in use as observation platforms, scouts and submarine hunters.
After the Great War, airships continued to be developed, mostly in civilian roles. A series of disasters in the 1930's CE, culminating in the burning of the Zeppelin Hindenburg, sharply decreased their popularity. Since 1923 CE some of them used helium as an alternative to the flammable hydrogen, though this is costlier. In World War II the USA once more employed airships as submarine hunters and mine finders, with quite some success. Static barrage balloons were also used by several countries to deter enemy night bombers.
In the present, air forces continue to experiment with modernized airships, though on low budgets. Intended use remains as before: reconnaissance and as communication platforms.