Analysis of long-endurance station-keeping flight scenarios for stratospheric airships in the presence of thermal effects.

• The relationship between the buoyancy and gravity is analyzed when the thermal effects are considered. • Three station-keeping scenarios are proposed and compared for the stratospheric airship. • The significance of pressure control and altitude control is revealed by the calculation and analysis. • An effective way to specify the helium's mass is presented when the thermal effects are considered. • The airspeed control is shown as an efficient way to cut down the energy consumption during the long-endurance flight. The ability to achieve long-endurance station-keeping flights makes stratospheric airships desirable platforms for the provision of communication and surveillance services. To maintain long-endurance flights, it is necessary to consider the problem of energy consumption. In this paper, we discuss long-endurance flight scenarios of stratospheric airships in the presence of thermal effects. The balance between buoyancy and gravity is influenced by thermal effects during the diurnal cycle. We perform a theoretical analysis based on the helium's mass, pressure differential, and altitude as the main factors. To verify the effectiveness of the control over the pressure differential and the altitude, three long-endurance flight scenarios are proposed and compared. Then, the corresponding optimization problems are constructed to determine the energy-minimum flight. Finally, further efforts are made to reduce energy consumption. The realization and limitations of two strategies for improvement are analyzed. A comparison with other scenarios shows the effectiveness of energy conservation. The study in this paper thus provides a reference for station-keeping applications of stratospheric airships. [ABSTRACT FROM AUTHOR]