After the invention of the balloon in 1783 inventors sought ways of steering a balloon independent of wind direction. It was Henri Giffard who produced a lightweight 3hp engine, which weighed only 350 lb. In 1852 his 70,500 cu ft hydrogen filled `Airship' ascended from the Paris Hippodrome and flew to 6 miles high. In 1884 another airship was built, the `La France' which had a 9hp electric engine and a top speed of 15 mph.
The first rigid airship was built by David Schwarz of Germany in 1895. This design set a precedent for many bigger and better airships built in France, Britain and the US over the next 40 years or so. Over the years there were many catastrophic accidents due to using hydrogen gas to fill the balloons, this gas frequently caught fire and exploded, the most notorious of these disasters is probably that of the colossal `Hindenburg' which caught fire on May 6th 1937 at Lakehurst, New Jersey killing 36 people.
After these disasters the US decided to use the much safer helium gas to fill their balloons, but due to the number of accidents public opinion had changed and airships were no longer used to carry passengers. It was during the Second World War that airships came into their own, the US used non-rigid airships for detecting minefields and as convoy escorts.
When the airship is ascending, air is released from the balloonets and the helium expands causing the airship to rise. When the airship wishes to descend, air is forced into the balloonets and the helium contracts which lowers the craft.
