(Scanned from Ermino Bagnasco's "Submarines of World War Two")

A modification of the Type J1, this boat differed in having two small storage cylinders aft of the conning tower.  These were used to store the sections of a dismantled seaplane.   The fuselage and floats went into one cylinder, while the wings went into the other.  The I-5 was the first Japanese submarine designed to carry an aircraft.

Polmar states that no catapult was provided, while Bagnasco says there was a small catapult abaft the conning tower.  Both sources agree that the handling of the aircraft was awkward, in that it had to be completely assembled before flight and completely disassembled afterwards.  The equipment for operating the aircraft was removed in 1940 and replaced by a second 14cm gun.

Polmar and Bagnaco also differ as to the arrangement of the tubes and the complement.  Polmar states that all six tubes were in the bow, while Bagnasco indicates four were forward and two aft.   The data in the table below are as provided by Bagnasco.

I-5 patrolled off Oahu at the start of the war.  She was lost to the destroyer escort USS Wyman 360 miles east of Guam on 19 July, 1944.