On the development of a parametric aerodynamic model of a stratospheric airship

Abstract

Following the current resurrection of large airship projects for stratospheric flight, a first-order potential flow panel method is presented to calculate pressure coefficients on a parametrically defined airship. Airships need three-dimensional grid definitions that often make difficult the execution of simple codes for preliminary results. A mesh-generation mechanism, appropriate for panel methods, is developed considering the different characteristic lengths of hull and fins. Thick and thin panels are defined, combined and properly attached among them to model the airship shape and the wake discontinuity surface. The classical formulation has been customised to both efficiently solve the potential problem and to derive interesting variables such as local velocity and surface pressure. After individual validations with thick ellipsoids and flat wings respectively, the solutions for the full vehicle are compared to tunnel tests of a representative airship body (Gertler 4154 Series 58) with fins. Pressure coefficient distribution and pitch moment coefficients of the body are predicted with very high accuracy. Even using only less than 4000 panels, overall error is smaller than about 5% and essentially null for the first half of the body. Furthermore, the speed of the problem setup and the solver make the development very appropriate to analyse preliminary designs under different flight conditions.