A Geometry-Sensitive Munk-Type Added-Mass Framework for Slender Airships

Classical Munk-type added-mass modeling remains a fundamental tool in airship flight dynamics because the displaced fluid mass is comparable to the vehicle mass and contributes directly to the generalized inertia. This paper investigates the applicability limits of classical Munk-type modeling for slender airships and develops a geometry-sensitive generalized framework based on actual hull contour information. The proposed formulation preserves consistency with the classical ellipsoidal limit while introducing discrepancy measures derived from the sectional area distribution and its longitudinal moment. The model is organized into a strict potential-flow added mass layer and a separate correction layer so that geometry-sensitive inertial effects are not conflated with non-potential aerodynamic corrections. Representative hulls are used to quantify the structural error of equivalent-ellipsoid approximations, and the Lotte airship is selected for a regularized literature-based assessment using published static and quasi-static aerodynamic coefficient curves. For the Lotte assessment case, the results show that the geometry-sensitive regularized model improves the representation of body-fixed normal force and pitching moment coefficient trends relative to the corresponding classical ellipsoidal baseline, with the clearest improvement in the pitching moment response. The analysis further indicates that the discrepancy associated with the second axial area moment is more influential for the moment response than the maximum thickness location parameter.