Propulsion

The stratospheric airships have large inflatable membranes capable of retaining the lifting gas. Moreover, they are equipped with additional interior bags that contain air, adapting the internal pressure to the one outside so that the airship maintains its shape with minimum effort. In other possible architectures helium is enclosed in the inner bags (gas bags) while the air is confined in the outside membrane, which gives the aerodynamic shape.

Given the dependency of aircraft performance from the meteorological conditions, a research lines exploits the benefits of having a better knowledge of atmospheric conditions in real time. Thus, analytical methods (in contrast to other extended approximate solutions) are used to find best trajectories for several figures of merit, including weather forecast modifications and the occurrence of path constraints.

Space debris is an environmental threat, a concerning safety issue and a cause of important economic loss. One of the main drivers for increasing the amount of space debris are the catastrophic collisions, i.e., those whose fragments are capable of triggering new catastrophic collisions with other space objects. The present project develops a description of such collisions by means of metamodels built from computational particle mechanics, providing a numerical characterization of a space hypervelocity collision.

In general, bibliography shows satisfactory validation studies (most of them in simple test cases) for particle mechanics codes. However, the computer workload requirements when considering not-trivial geometries for the satellite and the impactor are very constraining. Moreover, detailed/complex structural definitions are required as geometry and materials are relevant, which may be the reason why current models misbehave when satellites with larger percentage of composites are involved.

However, the casuistry of the space impacts makes it unfeasible to simulate all the possible collision conditions. They range from imperceptible small objects to large ones generating shockwaves and breaking satellite parts that are far from the impact area. in this study, a macroscopic surrogate mode is fed by the results of the detailed mechanics (so-called microscopic) simulations and the available validation cases. This new catastrophic break-up metamodel provides advantages such as speed and continuity of input domain, with accuracy incrementally improved as new real or simulated cases are included.

This low cost non-intrusive method allows the assessment of the real wind conditions in the airfield both visually and computationally by tracking helium filled bubbles along their ascending path. The system can remotely track bubble clusters up to 300 m height, reaching very good accuracy after filtering the readouts from several cameras. This is an interesting solution for researchers in air traffic management or unmanned vehicle operations for the last phase of the mission, were incidents concentrate.