Hiro Type 14
The Hiro Type 14 engine, (full designation Hiro Type 14 500 hp water-cooled W-12), was a water-cooled twelve-cylinder W engine built by the Hiro Naval Arsenal (Hiro Kaigun Ko-sho) for the Imperial Japanese Navy. The Hiro Type 14 engine design was based on the Napier Lion. Like the parent engine, and the Lorraine 12 Eb, it had three banks of four cylinders each, with the center bank upright, and the other two banks angled outward 60 degrees. In some cases the W engine is referred to as the broad arrow configuration, due to its shape resembling the British government broad arrow property mark. The first aircraft to be powered by a Type 14 engine was the Hiro H2H flying boat. Design and development Japan's military leaders discovered the value of aircraft while participating in World War I. It was necessary to import all of its military aircraft and engines as there was no aviation manufacturing industry in Japan at that time. The Imperial Japanese did not want to rely on foreign products, yet that was all that was available. To remedy this, Japan began importing state-of-the-art aircraft from around the world, and after close examination and study they incorporated the