Structural Considerations

Materials
The prototypes were obtained using conventional additive manufacturing methods (3D printing) in PETG, a thermoplastic denser than the test tank fluid (fresh water). Given the exposure of the structure to an underwater environment, it is desired that hygroscopicity is minimized.

Internal Structure and Ballast
In order to keep the external geometry proposed in the literature unchanged, the adjustment of buoyancy and convergence of the longitudinal coordinates of the centers of mass and buoyancy to avoid free-floating rotations were achieved through the positioning of a cavity inside the geometry. The characteristic dimensions of the cavity are dependent on the density of the selected material. Before the torpedoes were printed, the post-print density was verified via the Archimedes method, as described by Spierings, Schneider, Eggenberger (2011). From this measurement the final geometries were generated.