The most marked feature of this unit was to be equipped with three axis lines (the only Italian submarine) driven by three petrol engines for a total power of 800 hp; for navigation in immersion, however, only the two external axes operated by two 77 Kw electric motors were used. The unit never gave good performances and therefore, above all in consideration of the dangerousness of the petrol used as fuel, it was not reproduced in other specimens.
Source: Military Navy
