The Z.511 transatlantic seaplane in company with the Z.515 light reconnaissance bomber seaplane behind.
Taken over by the Regia Aeronautica and given the standard camouflage, the Z.511 became the Z.511A.
In 1939 Zappata designed the four-engined Z.511 transatlantic passenger airliner. Originally intended for Alitalia's South Atlantic route, the Z.511 featured a two-level fuselage with crew and passenger compartments above mail and freight bolds below. Sleeping accommodations for sixteen persons were to be provided. However, the prototype was not completed until after the outbreak of war, flying for the first time in September, 1943.
Another example was built concurrently. An excellent and rugged design, the Z.511 could moor on waves nearly seven feet high with little adverse effect, and had a maximum range of 2796 miles.
An ambitious plan for raiding the New York was under study in 1943 by the Regia Marina, using "Porcellini" man-guided torpedoes, already successfully employed against the British battleship Valiant at Alexandria. The two Z.511 seaplanes were to fly the Atlantic, taxying in under the radar screen to a point from which the manned torpedoes could be launched. No provisions were made for retrieving the naval personnel after their attack. Before this project could be realized, the two Z.511's were damaged beyond repair at Lake Trasimeno by strafing Allied aircraft. The military Z.511A was powered by four 1500 h.p. Piaggio P.XII R.C.35 radial engines giving a maximum speed of 264 m.p.h., a cruising speed of 205 m.p.h. and an alighting speed of 84 m.p.h. It could climb to 13,120 ft. in 16 minutes. Empty and loaded weights were 45,012 lb. and 73,830 lb. respectively. Span was 131 ft. 2 1/2 in. length 93 ft. 6 in. height 36 ft. 1 in. and wing area 2098 sq. ft.