Transmission gears of a Zeppelin NT, a modern airship. A mechanic checks and tweaks the gears. These drive one of the airship's three propellors. It has one propellor either side and one at the back. They have a power of 147 kilowatts each and the side propellors can be turned 90 degrees upwards or 30 degrees downwards to aid manoeuverability. With a full payload the airship has negative buoyancy and so has to rely upon lift gained from the engines, which can power it 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.