Unmanned solar energy powered air vehicle climbing along quasi-cyclic trajectory optimization

Аuthors

Brusov V. S.^1*, Nefedov L. V.^2**, Lishchinskii M. A.^2***

1. Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
2. Company «Tupolev», 17, nab. Akademika Tupoleva, Moscow, 105005, Russia

*e-mail: vsbrusow@mail.ru
**e-mail: skaver@yandex.ru
***e-mail: mishali@yandex.ru

Abstract

The capabilities of modern photovoltaic transducers form the performances of the solar energy powered UAV. Solar energy ensures the flight at low speeds. High-altitude flight allows avoid the impact of clouds and provides a large view scope. High-altitude flight is carried out within the high kinematic viscosity environment that significantly reduces thereby the Reynolds number. An important feature of the aircraft consuming solar energy to maintain its flight consists in specific range of flight heights and speeds, characterized by low Reynolds number. These flight conditions are associated with non-linear dependence of aerodynamic characteristics from the incidence angle, which complicates the use of traditional methods to optimize the flight path. The flying vehicles of such kind require the technique allowing optimize the flight path with allowance for these features. The proposed climbing trajectory optimization method partitions the optimization process into two stages. The first stage consists in flight parameters region characterization, guaranteed to exceed the specified value, while the second stage is the stage of trajectory providing minimum power consumption search. The search for the trajectory allowing minimum power consumption is carried out by the direct numerical method, without characteristics linearization. Such an approach allows optimize climbing trajectory of the aircraft having non-linear aerodynamic characteristics, peculiar to the flight at low Reynolds numbers. We obtained climbing trajectories with allowance for Reynolds number and without it. The results show that energy consumption while climbing with allowance for non-linear aerodynamic characteristics are about 4% higher than the results obtained without the regard of those non-linarites. This may cause the energy shortage for flight support and lead to multi-day mission failure. Optimization of high- altitude solar energy powered UAV flight path requires regard of Reynolds number effect of aerodynamic characteristics. The flight paths computation of the UFVs of such kind is worthwhile to carry out by numerical methods, stable to aircraft aerodynamic characteristics non-linarites.

Keywords:

solar-powered unmanned air vehicle, flying wing, UAV long-period longitudinal movement, quasi-cyclic trajectory

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