Lighter-Than-Air Aircraft

Lighter-Than-Air Aircraft groups the earliest successful flying craft, machines that rise and travel by buoyancy rather than by generating aerodynamic lift over a wing. It covers the hot air balloon, whose heated envelope displaces cooler surrounding air to gain altitude, and the powered, steerable airship, which adds an engine and control surfaces to a buoyant gasbag so a crew can navigate rather than merely drift. Both trace to the same basic physical principle, a lifting gas or heated air lighter than the surrounding atmosphere, and both preceded the fixed-wing airplane by well over a century as the first practical means of sustained human flight. The group distinguishes buoyant flight from the heavier-than-air aircraft, rotorcraft and rocket-propelled craft classed elsewhere in this atlas.