Airship and method of operation

A substantially spherical aircraft comprising an outer envelope having a leading portion and a trailing portion, said aircraft having buoyancy apparatus operable to maintain said aircraft aloft, propulsion and directional apparatus co-operable to conduct said aircraft;

• and at least one boundary layer separation suppression element operable to encourage said aircraft to proceed as conducted and to create, during operation for forward conduct a zone of lowered fluid pressure substantially adjacent to said trailing portion of said aircraft and to shift away from said leading portion, a point at which airflow about said outer envelope srparates therefrom, said bouyancy apparatus including an envelope mounted within said aircraft, and said envelope containing a buoyant lifting fluid.

A substantially spherical aircraft, said substantially spherical aircraft having a weight and an internal volume, said aircraft having an outer, load-bearing envelope defining said internal volume, buoyancy apparatus operable to maintain said aircraft aloft, and propulsion and directional apparatus co-operable to conduct said aircraft;

• said buoyancy apparatus including an inner envelope mounted within said outer, load bearing envelope, said internal volume being maintained at an elevated pressure relative to the external, ambient pressure to maintain said substantially spherical shape of said aircraft, said inner envelope containing a buoyant lifting fluid;
• said inner envelope being variably inflatable to occupy a variable portion of said internal volume;
• and, under ambient conditions at sea level on a 59 F day, when said envelope is inflated to as little as 70% of said internal volume, said envelope provides a buoyant force at least as great as said weight.