Yokosuka Navy 1-go Experimental Submarine-borne Reconnaissance Seaplane.

The Japanese Navy had a strong interest in the use of submarine-borne reconnaissance seaplanes, and one of several designs for this type was begun at the Yokosuka Naval Arsenal in 1925, based on a Heinkel U 1 submarine-borne seaplane designed by Carl Caspar, former owner of the Hanseatischen Flugzweugwerke in Germany. One of these aircraft, better known as the Caspar U 1, had been imported in 1923 and the Yokosho design was a near duplicate in layout and dimensions.

This Yokosho design was a cantilever biplane having one-piece upper and lower wings without interplane struts. The structure was of metal and wood, with light metal fuselage skinning and the wings were fabric covered. The twin-floats and wings were detachable from the fuselage and these components could be stowed in a tubelike hangar 7.4 m (24.7 ft) long and 1.7 m (5.5 ft) in diameter. The aircraft could be assembled in 4 min by 5 mechanics and became airborne in a total of 15 to 16 min. Dismantling was accomplished in 2 min by five mechanics.

Completed in 1927, this was the smallest aircraft in Japan. Although small, it was a rugged aircraft of good design with light-weight metal skinning. During 1927-28 it was tested aboard the submarine I-21 which was equipped with a hangar for this purpose, but the aircraft was not developed further. The experience gained with this project was useful in the later development of the Yokosho 2-go Reconnaissance Seaplane. Similar research at this time was being conducted in the United States and Great Britain, but none of the projects were developed to an operational level.

Technical Data
Manufacturer: Yokosuka Kaigun Ko-sho (Yokosuka Naval Arsenal).
Type: Single-engined carrier-borne reconnaissance seaplane.
Crew (1): Pilot in open cockpit.
Powerplant: One 80 hp Gasuden-built Le Rhone nine-cylinder rotary engine, driving a four-blade wooden propeller.
Dimensions: Span 7.20 m (23 ft 7 1/2 in); length 6.205 m (20 ft 4 1/4 in); height 2.39 m (7 ft 10 in); wing area 15.2 sq m (163.616 sq ft).
Weights: Empty 400 kg (881 lb); loaded 520 kg (1,146 lb); wing loading 34.2 kg/sq m (7 lb/sq ft); power loading 6.5 kg/hp (14.3 lb/hp).
Performance: Maximum speed 83 kt (95.57 mph); endurance 2 hr.
Production: A total of 1 1-go prototype was built by Yokosuka Kaigun Ko-sho in 1927.