The Aerodynamics sub-team is responsible for the aerodynamic design, trajectory analysis of the rocket, developing configurations and automatic control systems to improve its performance. To achieve that the sub-team develops its own tools, performs CFD analysis and wind tunnel testing.

The sub-team consists of two departments:

  • Aerodynamic Design
  • Automatic Control

Aerodynamic design department

The main goal of the aerodynamic design it to design a stable rocket that reaches the target apogee precisely. The design process consists of multiple stages that constant improvements are taking place until the requirements are met and the desired result is accomplished.

In the first stages lower fidelity tools are used to save time, like OpenRocket, while high fidelity in the latter stages (e.g. CFD). Moreover, wind tunnel testing is performed to validate the results.

Ανάλυση ευστάθειας πυραύλου στο OpenRocket
Stabilty analysis in OpenRocket

In OpenRocket the initial configuration layout and sizing is determined while an estimation of the weights is given. Additionally, aerodynamic characteristics (e.g drag) and stability are calculated while trajectory analysis is performed. The best accuracy is provided by Computational Fluid Dynamics Software (CFD) where again aerodynamic characteristics, stability is calculated while the airflow around the rocket is studied. For this purpose, the sub-team uses the pre-processor ANSA from Beta CAE systems for meshing and ANSYS CFD/Fluent as solvers.

Διακριτοποίηση Nosecone στον προ-επεξεργαστή ANSA της BETA CAE Systems
Nosecone meshing in pre-processor ANSA from Beta CAE systems

The final dimensions of the nosecone and fins are determined with trade studies realized through CFD analysis.

During the design process the rare opportunity is provided to study complicated aerodynamic phenomena like flow separation in fins and shockwave formation at supersonic speeds.

Flow seperation over a fin
Shockwave formation on PEGASUS nosecone

Import part of the sub-team is the Research & Development of new configurations, mechanisms, and design tools. The most important ones until now are the:

  • Tailcone: Using project PEGASUS as a baseline, the effects of a tailcone in a rocket’s performance were studied, with the intention to be used it in future projects.  Its purpose is to reduce the drag of the rocket, by minimizing vortices generated from the base of the rocket..
  • Performance assessment and trajectory analysis: The sub-team is currently developing a performance assessment and trajectory analysis tool which will replace OpenRocket. This will provide better accuracy and more precise simulation while maintaining the ease of use OpenRocket provides.
Ενσωμάτωση Tailcone σε πύραυλο
Tailcone intergration

Automatic Control Department

The goal of the newly formed department is to develop controllers and mechanisms to improve performance and dynamic behavior of the rocket. This is achieved through analysis, modeling of physical and automatic control systems and extraction of transfer functions. Necessary for the design and performance assessment of the controller is the simulation of the systems. These are realized in Matlab and Simulink.

Ενσωμάτωση Airbrakes σε πύραυλο
Airbrake intergration

Currently an airbrake system is being developed, which goal is to control the apogee of the rocket. This is achieved by controlling fins, vertical to the airflow, that increase rockets drag. The first version of the controller and mechanism are designed, and the simulation software as well (in collaboration with the aerodynamic design department), while a prototype remains to be built for evaluation. With the data provided the systems development will continue, increasing its complexity through the number of the variables controlled, and increasing the accuracy of simulation software.

Future goals include the development of a roll control system and a active fin control as well which will allow full control of the rockets orientation.