The Navy Yokosho Ro-go Ko-gata Reconnaissance Seaplane was the first Japanese-designed aircraft to enter production for the Japanese Navy, and was in service into the late 1920s.
During the First World War Lt Chikuhei Nakajima (later to found his own aircraft company) worked at the Yokosho naval arsenal, where he produced a number of experimental seaplanes. During 1917 Lt Kishichi Umakoshi, one of his assistants, began work on a design for a new reconnaissance seaplane.
The Ro-go Ko-gata was a three bay biplane powered by a single engine. It had short twin floats and a third float under the tail. The structure was wooden, with a fabric covering. The wings could be folded to the rear for storage. Very early aircraft were powered by a 140hp Salmson engine. This was replaced by a 200hp Salmson engine on some of the aircraft produced at Yokosho. During the Yokosho production run the engine was changed again, to a 200hp Mitsubishi type Hi licence-built Hispano engine, and this was used on the majority of aircraft.
The first prototype was ready by the autumn of 1917. Flight tests began at the start of 1918 and the new aircraft proved to be superior to any then in Japanese Naval Service (a mix of imported designs), in particular a number of Farman Pushers.
The first four aircraft were built at Yokosuka in 1918. They were then accepted for Naval Service, with the designation Ro-go Ko-gata. In the system in use at the time this made it a Reconnaissance aircraft (Ro-go), while Ko-gata indicated that it was the first Yokosuka reconnaissance aircraft to be accepted (effectively the equivalent of Model A).
A total of 218 aircraft were built. Yokosho produced thirty-two in 1917-21, with a mix of Salmson and Mitsubishi engines. Aichi produced eighty between 1920 and 1924, all with the Mitsubishi engines. Nakajima produced 106, their first Naval aircraft, between 1920 and 1925, again all with the Mitsubishi engine.
In April 1919 three of the early production aircraft had one seat removed and extra fuel tanks installed. They were then used for a record breaking flight. This involved a course that took them from Oppama to Kure, then to Chinhae near Pusan in Korea, then to Sasebo and finally back to Oppama. The record came on the final leg when Sub-Lt Kanjo Akashiba flew 808 miles in 11hr 35min.
The aircraft was in service from 1921 until 1926, operating alongside the Navy's Hansa Type Reconnaissance Seaplane. Most were then released for civil use, but some did remain in service until 1928.
Engine: Mitsubishi Type Hi (Hispane-Suiza E) nine-cylinder water-cooled radial engine
Span: 51ft 6in
Length: 33ft 4in
Empty weight: 2,358lb
Loaded weight: 3,589lb
Max speed: 96.72mph
Climb Rate: 4min to 1,640ft
Range: 483 miles
Endurance: 5 hours
Armament: One dorsal mounted 7.7mm machine gun