“The Hiro H1H (or Navy Type 15) was a 1920s Japanese bomber-reconnaissance biplane flying boat developed from the British Royal Navy’s Felixstowe F.5 by the Hiro Naval Arsenal for the Imperial Japanese Navy. Powered by either imported Lorraine W-12 or BMW VII engines, the H1H had a maximum cruising speed of 92 knots (106 mph) and a flight endurance of over 14 hours.
“Hirosho (Hiro kaigun kosho, Hiro Naval Arsenal) was established on 1 Aug 1920, under the name Aircraft Department, Hiro Branch Arsenal, Kure Naval Arsenal, as the navy’s first real aircraft repair and manufacturing factory. Prior to that, two naval aircraft factories were already operating at Yokosuka and Sasebo, but space was very limited.
“To increase production capability for the Navy, the Kure Naval Arsenal expanded by establishing the Hiro Branch Arsenal three miles southwest of Kure. This new factory, known by its acronym Hirosho, was completed in October 1921, and licensed production of the F.5 flying boats was begun.
“Following licensed production of the Felixstowe F.5 for the Imperial Japanese Navy the company developed an improved version known as the H1H or Navy Type 15. A total of 65 H1H of differing variants were built by the Hiro Naval Arsenal, Yokosuka Naval Arsenal and the Aichi Aircraft Co.
“The Navy Type 15-I was built with a wooden hull and had a longer upper wingspan; the Navy Type 15-II had an all-metal hull and four-bladed propellers. The H1H remained in front line naval service through the 1930s before being retired in 1938 although a few were retained for training purposes into the 1940s.”
Maximum speed: 106 mph (170 km/h, 92 kn)
Endurance: 14 hours 30 minutes