Tools for the Conceptual Design of a Stratospheric Hybrid Platform 2020-01-0025
The Italian Aerospace Research Center is currently developing the design of a HAPS (High Altitude Pseudo Satellite). Different HAPS configurations have been proposed in recent years. Airbus Zephyr family and Aurora Odysseus are based on the flying wing configuration. Thales Stratobus is an airship, while Google Loon project is based on balloons.
Our proposal concerns a hybrid configuration where the weight is balanced by both aerodynamic and aerostatic forces.
In this paper we present the tools we have implemented to develop the conceptual design of our platform. The tools have been implemented in Mathworks Matlab® and Grasshopper® integrated with Rhino 3-D.
In the Matlab environment, we have developed an optimization algorithm which can estimate some
geometric and energetic global parameters of the platform (weight, surface, volume, required power, width, length and height) using as input the desired speed, altitude and period of the year in which the mission will be performed.
In this algorithm, we have included a modelling of the principal subsystems affecting the overall platform weight and energy consumption and availability, the aerodynamic and structural parameters using semiempirical formulations.
The results provided by this algorithm are based on the hypothesis that the shape of the platform could be approximated as a rectangular wing; consequently, geometric parameters are calculated with a certain degree of approximation.
To improve results, the output of optimization algorithm in Matlab is used as a starting point in a graphical tool developed in Grasshopper®. Thanks to its connection with Rhino 3-D modeler, it allows more accurate calculation of geometries, taking into account the desired configuration of the platform.
After definition of the real shape, structural elements (these are principally inflatable elements) can be designed with more precision improving the final estimate of the overall weight of the platform and wing profiles can also be included.
Moreover, the 3-D rendering of the platform shape is used as input for preliminary CFD (computational fluid dynamics) and FEM (finite element method) calculations.
Vincenzo Rosario Baraniello, Giuseppe Persechino, Roberto Borsa
CIRA - Italian Aerospace Research Centre