Zeppelin NTs on the ground. These modern airships are built by Zeppelin Luftschifftechnik GmbH, a company which claims lineage from those founded by Frederick von Zeppelin in the early 20th century. They use helium rather than flammable hydrogen for buoyancy. At 75 metres in length they are smaller than the original Zeppelins. With a full payload they have negative buoyancy and so have to rely upon lift gained from the engines, which can power them to speeds of up to 125 kilometres per hour. The first prototype airship was launched in 1997 and since 2001 they have been used to give flights for tourists and as observation platforms for television crews at major events.