Abstract
Dynamic soaring is a non-powered flight mode that enables extremely high speeds by extracting energy from thin shear wind layers. Trajectory optimization is applied to construct solutions of the maximum speed achievable with dynamic soaring and to determine characteristic properties of that flight mode, using appropriate models of the vehicle dynamics and the shear wind layer. Furthermore, an energy-based flight mechanics model of high-speed dynamic soaring is developed, with reference made to trajectory optimization. With this model, analytic solutions for high-speed dynamic soaring are derived. The key factors for the maximum speed performance are identified and their effects are determined. Furthermore, analytic solutions for other, non-performance quantities of significance for high-speed dynamic soaring are derived. The analytic solutions virtually agree with the results achieved with the trajectory optimization using the vehicle dynamics model. This is considered a validation of the energy-based model yielding analytic solutions. The analytical solutions are also valid for the high subsonic Mach number region involving significant compressibility effects. This is of importance for future developments in high-speed dynamic soaring, as modern gliders are now capable of reaching that Mach number region.
Highlights
Dynamic soaring is a flight mode by which an energy gain can be achieved from horizontally moving air so that the energy loss due to the drag can be compensated and non-powered flight becomes possible [1,2]
Trajectory optimization is used as a means to determine the maximum speed achievable in high-speed dynamic soaring and to find out characteristic properties of that flight mode
With reference to the trajectory optimization results, an energy-based flight mechanics model is developed with the goal to derive analytic solutions
Summary
Dynamic soaring is a flight mode by which an energy gain can be achieved from horizontally moving air so that the energy loss due to the drag can be compensated and non-powered flight becomes possible [1,2]. The The possibility of gained gaininginenergy for dynamic non-powered has stimulated research interest in experience high-speed soaringflight is an item of interest This can relate to testingas of dynamic soaring where strong shear, easy access, and relatively obstruction-free usinginitial the wind an energy source forthe technical applications. Further to the goal of the present paper, it is shown that the analytic solutions derived in this on the aerodynamic characteristics, involving relationships that are more complex This is important for paper are valid for the high subsonic Mach number region, where compressibility exerts futuresignificant developments dynamic soaring ininvolving order to be able to solve related to the effects in onhigh-speed the aerodynamic characteristics, relationships thatproblems are more complex. This is important for future developments in high-speed dynamic soaring in order to be able to solve problems related to the compressible Mach number region, as this region is reached by modern
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