eloquent wrote:As far as I understand it, a dirigible is another word for airship. The name actually comes from the french word meaning steerable, because airships/dirigibles can be steered (as opposed to balloons which cannot). Anyway a zeppelin is a much more specific term for a particular type of airship which is always filled with hydrogen, and actually refers to the brand.
So if airship were equivalent to automobile
dirigible = car
zeppelin = Volkswagen
The Hindenberg (built by the Zeppelin Company) and the Graf Zeppelin II (her sister ship) were designed to be filled with helium, but there was a general shortage of He at the time and the Americans, who were the major suppliers, didn't have enough to keep all their own airships aloft, let alone sell this valuable materiel to a potentially hostile foreign power.
As a consequence, the Hindenberg was filled with hydrogen instead and the extra lift that it gave provided an increase in carrying capacity. As it is now believed that the real cause of the fire was static electricity igniting the covering (it was doped with a aluminium/cellulose compound that's chemically very similar to the stuff that's put in the Space Shuttle's solid-fuel boosters!) rather than the hydrogen inside it, the Hindenberg's fate would probably have been the same even if she had been filled with helium.