Unconventional hybrid airships design optimization accounting for added masses

This paper describes the implementation of a framework which can be used to optimize the external shape of an unconventional airship configuration. This framework includes the estimation of Added Masses (AM) which captures the contribution of the dynamic effect related to the acceleration of a body immersed in a fluid having a similar density to that of the body itself. A computationally efficient routine to compute AM has been implemented in a heuristic optimization loop based on a Particle Swarm Optimization (PSO) algorithm, and has been integrated into a simple model which provides hybrid airship's aerodynamics characteristics. As a case study, the take-off distance of a hybrid airship has been optimized by the methodology, and it is used to show the effect on the optimization loop and the errors arising from using conventional approximated AM evaluation methods. The proposed set of simulations clearly evaluates the errors expected on the unconventional airships performances when approximated methods are used in the evaluation of the AM.