VHF Omnidirectional Range (VOR) Experimental Positioning for Stratospheric Vehicles

Optimal shape design of an airship based on geometrical aerodynamic parameters

Background

Conventional airship mathematical modeling usually involves six coupled degrees of freedom and two inputs, namely tail and thrust. The current study focuses on aerodynamic modeling. The aerodynamic model is developed in 3D-space based on plane semi-empirical model of a symmetric airship. The model depends on the main geometrical parameters of the airship. The study introduces an optimal shape design of the airship. The objective function is established to reduce drag and the effect of side flow and increases both lift force and pitching moment. Three types of airship shape construction are investigated, namely NPL, GNVR, and Wang.

Results

MATLAB genetic algorithm toolbox is used to obtain the optimal shape. The population size is 50 and the number of generations is also 50 for NPL, GNVR and Wang shapes at each corresponding angle of attack $$(\alpha =\left[ -20^\circ ,20^\circ \right] )$$ ( α = - 20 ∘ , 20 ∘ ) and side-slip angle $$(\beta =\left[ -20^\circ ,20^\circ \right] )$$ ( β = - 20 ∘ , 20 ∘ ) . The shapes are compared to select the best fit within the operating range. To get the optimal shape, weighted averaging is performed on the optimal solution.

Conclusion

The GNVR geometric construction technique is the best method to generate the optimum shape of the airship in the presence of side-slip angle effect with the utilized objective function that reduces drag and side flow and increases lift and pitching moment.

Multidisciplinary Optimization of Thermal Insulation Layer for Stratospheric Airship with a Solar Array

Stratospheric airships with a solar array have demonstrated overwhelming superiority in many aspects, such as earth observation, meteorological survey, and communication relay. The solar array supplies sufficient power for the airship to be in flight for months, but excessive heat is also transferred to the airship, causing high overpressure of inner gas. However, the optimal arrangement of the insulation layer on the airship has not been investigated. The theoretical method, including the geometry, thermal, and energy models, is developed and validated. The distribution of the temperatures and power of the solar cells, with different installation angles on the curved surface, is investigated. The thickness of insulation layer has a significant effect on the solar output power and internal pressure of the airship. An optimized configuration of the insulation structure is proposed, in order to improve the total output energy of solar array. The optimized configuration of insulations helps to reduce the structural mass by 24.9% and increase the payload mass by 9%. Moreover, the optimized arrangement improves the output energy of solar array in a year, and the maximum improvement is 8.2% on the winter solstice. The work displays the optimization of the thermal insulation layer for the stratospheric airship with a solar array, in order to improve the everyday energy acquirement during flight in a year.