Transportation: Balloons

[macdobhran]

One of the most primitive flying machines is actually one of the most efficient. A balloon, either hot-air or helium, can remain aloft for weeks. The disadvantage, however, is a lack of propulsion. Balloons depend largely on wind and thermal currents to carry them. Unless you have extensive experience, heading off in a balloon may do little more than leave you hanging helplessly above hostile ground.