Introduction and application of PyPAD, a framework for multidisciplinary airframe design

The preliminary design of an aircraft is a complex task involving a lot of different disciplines and it is becoming more challenging in the future due to the reduced budget and compressed time. At the same time new projects present new technical challenges due to the request for highly demanding performances, in order to reduce the fuel consumption (cost and environment impact) and to increase the payload. The preliminary design problem involves different disciplines, like: Aerodynamics, Controls, Regulations, Performances, Systems Definition, Design, Loads & Aeroelasticity, Structural Sizing, etc.. The present work focuses on the development of an integrated framework suitable for preliminary airframe design, called PyPAD (Python module for Preliminary Aircraft Design). The modules developed until now allow for the definition of multi fidelity aero-structural models starting from a CPACS input file and to compute static loads (trim) and utter margin with the minimum effort by the user. Moreover PyPAD is able to compute the dynamic response under all the different load conditions, including discrete and continuous gust, nodal forces, command inputs. The tool is also able to export the state-space aeroelastic models tacking advantage of the modern state space model realization. In this way all the loads prescribed by the regulations can be computed in a fully automatic approach. A complete test case, starting from the CPACS input and ending with the definition of structural, aerodynamic and aeroelastic models and with the computation of different design loads is reported.