Primary parameters determination for year-round solar-powered aircraft of wing-sail type at higher latitudes

Exploration of the capability of a solar-powered aircraft for year-round station keeping at higher latitudes is of great significance for the enhancement of its operational value. In this paper a model of power area density for PV modules arbitrarily oriented is first established which takes into consideration the temperature of the PV modules, flight altitude, flight latitude, and year-round seasons. The analysis on power absorption shows that the rotation angle of 90° is the optimal in the azimuth tracking method for a pair of sail tails in use. Secondly, a conceptual design methodology of solar-powered aircraft of a wing-sail configuration is developed which integrates the configuration design with energy absorption, and its formulations include mass component parameterization, aerodynamic efficiency, Kriging surrogate model and quantum behaved particle swarm optimization (QPSO) algorithm and its fitness function. Thirdly, a comparison of design methodology is conducted for the wing-sail configuration and wing-only configuration. Finally, a case study of the wing-sail configuration is conducted at the latitude of near 45°N and the altitude of higher than 18 km and its capabilities of operational altitude, payload-carrying and operational latitude in a whole year are investigated from 23.5°N to 55°N. The results show that in contrast with the traditional configuration, the wing-sail configuration improves power absorption characteristics at higher latitudes near winter, shortens the wingspan and reduce the wing area effectively, improves cruise velocity and makes year-round operation at higher latitudes feasible and efficient. These applications demonstrate the validity of the proposed design methodology of primary parameters of the wing-tail configuration solar-powered aircraft.