41. The wing spars were duralumin structures, though the first of the two Mussels had spruce ribs. 42. The rear fuselage section was a large, flat sided duralumin beam with frames and riveted skin. 43. The fuselage was built around four longerons, with rectangular frames and covered in longitudinally ribbed duralumin . 44. The wings were built around twin duralumin spars and pine and plywood ribs and had plywood leading edges. 45. The forward portion was clad in duralumin , and the remainder covered with fabric laced to the framework. 46. The hull is made from duralumin and features a stepped shape, similar to most powered flying boats. 47. They shared the same all-metal structure, mostly Duralumin covered with narrow aluminium strips applied longitudinally. 48. It used a new alloy called Alclad that combined the corrosion resistance of aluminum with the strength of duralumin . 49. In the final episodes, Duralumin stages a coup d'�tat to help Mr . X conquer Silverland. 50. The fixed tail was built of pine and plywood-covered, the moving surfaces duralumin with fabric cover.
