Abstract: An envelope holds gas in a lighter-than-air aircraft. The envelope has an outer shell, an inner wall, a compressor, and a valve. The outer shell has an upper surface, a lower surface, a leading edge, a trailing edge, opposing side surfaces, and an airfoil-shaped lateral cross-section. The inner wall divides the outer shell into high and low pressure chambers. The compressor is disposed between the high and low pressure chambers and controlled to selectively force gas from the low pressure chamber to flow into the high pressure chamber. The valve is disposed between the high pressure chamber and the low pressure chamber and controlled to selectively permit gas from the high pressure chamber to flow into the low pressure chamber.

Abstract: An envelope is disclosed for holding gas in a lighter-than-air aircraft. The envelope includes a shell having a leading edge, a trailing edge, an upper surface and a lower surface. The upper surface and the lower surface each extend between the leading edge and the trailing edge. The shell has an airfoil-shaped cross-section having a reflex camber quality.

Abstract: An orientation system is disclosed for a lighter-than-air aircraft having a lower stage suspended from an envelope. The orientation system includes a swivel and a plurality of thrust generators. The swivel is affixed between the envelope and the lower stage. The swivel is oriented for allowing the lower stage to rotate with respect to the envelope. The plurality of thrust generators are affixed to the lower stage. At least some of the trust generators generating differential thrust produces a change in rotation of the lower stage with respect to the envelope.

Abstract: An orientation system is disclosed for a lighter-than-air aircraft having a lower stage suspended from an envelope. The orientation system includes cords interconnecting the envelope and the lower stage and means for adjusting the length of at least one of the cords between the lower stage and the envelope. Adjusting the length produces a shift in the angle of attack of the envelope with respect to the lower stage.

Abstract: An envelope is disclosed for holding gas in a lighter-than-air aircraft. The envelope includes a shell having upper and lower hemispheres. The upper hemisphere has the shape of a hemisphere of a generally oblate spheroid defined by equatorial radii and a polar radius. The lower hemisphere has the shape of a hemisphere of a generally oblate spheroid defined by equatorial radii and a polar radius. The lower hemisphere is inverted compared to the upper hemisphere. The equatorial radii of the upper hemisphere are equal to the equatorial radii of the lower hemisphere. The upper hemisphere is joined with the lower hemisphere at their respective equators. The volume of the upper hemisphere is greater than the volume of the lower hemisphere. The height of the shell is less than the diameter of the shell at the joined equators.