The Yokosho 1-go Reconnaissance Seaplane was designed to be operated from a submarine, and was successfully tested but didn't enter production.
The aircraft was based on the Heinkel U 1, better known as the Casper U 1 after its designer, Carl Casper. He had a background in the aircraft industry, having once owned Hanseatische Flugzeugwerke (better known as Hansa-Brandenburg). One U 1 was imported into Japan in 1923, and it was used as a pattern for the 1-go.
The 1-go was a cantilever biplane. The upper and lower wings were both single pieces and could be removed from the fuselage, as could the twin floats. All five items could then be stored in a 7.4m by 1.7m hanger that could be carried on a suitable submarine. The main structure was a mix of metal and wood. The fuselage had a light metal skin, the wings were fabric covered.
The aircraft was designed to be easy to assemble or disassemble, essential for use on a submarine. It could be assembled by five men in four minutes, and airborne in 15 minutes. It could be dismantled in 2 minutes, although even that might not be quick enough if its submarine was under attack.
The sole prototype was completed in 1927. It was successfully tested from the submarine I-21 in 1927-28, but work then moved onto the Yohosho 2-go Reconnaissance Seaplane, which entered service as the Navy Type 91 Reconnaissance Seaplane (E6Y1).
Engine: Gasuden-Le Rhône 9 cylinder air-cooled rotary engine
Span: 23ft 7.5in
Length: 20ft 4.25in
Height: 7ft 10in
Empty weight: 881lb
Loaded weight: 1,146lb
Max speed: 95.57mph