Axis-occupied Europe lacked strategic materials such as tungsten, tin and some commodities such as rubber.

[2] For surface running, the boats were powered by two 1,300-brake-horsepower (969 kW) diesel engines, each driving one propeller shaft.

On the surface, the R class had a range of 12,000 nautical miles (22,000 km; 14,000 mi) at 9 knots (17 km/h; 10 mph); submerged, they had a range of 110 nmi (200 km; 130 mi) at 3.5 knots (6.5 km/h; 4.0 mph).

Some boats may have been equipped with a pair of internal 45 cm (17.7 in) torpedo tubes in the bow and stern.

[2] Twelve boats were ordered, but only two were completed, by Tosi: The remaining 10 hulls were scuttled incomplete and scrapped after the war.