Hiro (Hirosho) Navy Type F.5 Flying-boat.

H1H1

 H1H3

As a result of the British Aviation Mission under the Master of Semphill, that helped to train the Japanese Naval Air Force during 1921 and 1922, approximately ten types of British aircraft were taken to Japan by sea for instructional purposes. Among these was the very advanced Felixstowe F.5 flying-boat for which the Japanese Navy intended to build for its own use. After securing the manufacturing rights, the Japanese Navy invited to Japan a team of twenty-one engineers from Shorts Brothers for that purpose. This group, under the leadership of Mr Dodds, a Shorts' engineer who arrived in Japan in April 1921, and began work at the Ordnance Department of the Yokosuka Naval Arsenal where the flying-boats were to be built. The Japanese contingent under British leadership were Capts (Ordnance) Ryuzo Tanaka and Tomasu Koyama, Lieuts Kishichi Umakoshi and Misao Wada, Engineer Masasuke Hashimoto and others. The manufacture of the Felixstowe F.5 was the start of many years of flying-boat construction in Japan.

In addition to the licenced manufacturing rights, Short Brothers supplied partially built assemblies to complete the first six* of the F.5s, in addition to assembly tooling and instruction in the manufacturing process. These F.5s were assembled at Yokosuka Arsenal, with the first one being completed in April 1921. Since the F.5 was already renowned throughout the world as an excellent twin-engined all-wood flying-boat, it was no surprise that those assembled in Japan had an excellent performance. When the first of them visited Tokyo, with a fly past in October 1921, there was impressed public reaction to their, then, enormous size.

Following these imported and Japanese-assembled aircraft, the flying-boat was put into full production at the Aircraft Department of the Hiro Naval Arsenal in the Kure area, beginning in October 1921. An additional forty F.5s were built by Aichi up until 1929.

The engines initially used in these aircraft were the imported Rolls-Royce Eagle, which developed 360 hp. As work developed, the Engine Factory of the Hiro Arsenal manufactured their first licence-built Lorraine engine in August 1924.

Variants
H1H1
    Variant powered by two 450hp (336kW) Lorraine W-12 engines.
H1H2
    Variant powered by either two 450hp (336kW) Lorraine W-12 or two 500hp (373kW) BMW VII engines.
H1H3
    Variant powered by two 450hp (336kW) Lorraine W-12 engines.

Specifications (H1H1)
General characteristics
    Length: 49 ft 7 in (15.11 m)
    Wingspan: 75 ft 4½ in (22.97 m)
    Height: 17 ft 0½ in (5.19 m)
    Wing area: 1345.53 ft² (125 m²)
    Empty weight: 8862 lb (4020 kg)
    Gross weight: 13448 lb (6100 kg)
    Powerplant: 2 × Lorraine W-12 piston engine, 450 hp (336 kW) each
Performance
    Maximum speed: 106 mph (170 km/h)
    Endurance: 14 hours  30 min
Armament
    2 × 7.7mm (0.303in) Machine Guns (one at bow cockpit and one midships)
    up to 300kg (661) bombs