The Yokosho E5Y Navy Type 90-3 Reconnaissance Seaplane was one of three designs accepted by the Japanese Navy to replace the earlier Yokosho Type 14 E1Y, but was only produced in tiny numbers.
In 1927 the Japanese Navy asked Aichi, Nakajima and Kawanishi to design an aircraft to replace the all-wooden E1Y with an aircraft using some metal in its construction. At the same time Yokosuka gave Jiro Saha the task of producing their own modified version of the design.
He took the design of the E1Y and introduced elements from the Heinkel HD 28 and from an Aichi design to produce the Type 14-2 Reconnaissance Seaplane Kai-1 of 1928. This used a welded steel tube fuselage, with space for a ventral machine gun. A new wing structure was produced and a 450hp Jupiter VIII radial engine was installed.
Yokosho only produced a handful of aircraft to this design, split between the Kai-I-C with a 450hp Lorraine engine and the Kai-I-D, with a Jupiter engine.
Production then switched to Kawanishi. In 1931 they produced two pre-production Kai-I-Ds as the Kawanishi Type G. This model was then accepted by the Japanese navy as the Type 90-3 Reconnaissance Seaplane E5Y1. Kawanishi produced this aircraft in two versions. Their E5K1 used the Jupiter engine. In this configuration that was little improvement on the Type 14-2. In an attempt to fix this Kawanishi produced some aircraft using a 500hp Type 91 water-cooled engine. Between the two types Kawanishi only produced 17 Type 90-3s, and the total production run was just over 20.
The Type 90-3 was a twin bay twin-float biplane, with a welded steel tube fuselage and wooden wing, both fabric covered. The floats were constructed of metal. The wings folded to the rear. The crew of three (pilot, dorsal gunner/ navigator and radio operator/ lower gunner, sat in open cockpits.
Despite being produced in such small numbers the Type 90-3 did make a name for itself. It entered service just before the Shanghai Incident, and was rushed into service on several units of the Japanese Navy (including the seaplane tender Notoro). These aircraft were active over Shanghai, and were given a great deal of publicity.
The E5Y wasn't the only one of the Type 90 designs to be accepted for production. The Aichi Type 90-1 Reconnaissance Seaplane (E3A1) was a version of Heinkel HD 56. The Nakajima Type 90-2 Reconnaissance Seaplane (E4N) was a modified version of the Chance Vought O2U Corsair, produced by Nakajima and Kawanishi.
Type 90-3 E5Y1
Engine: Jupiter VIII or IX
Span: 47ft 5.25in
Length: 35ft 5.35in
Height: 15ft 6.75in (wings folded)
Empty weight: 4,078lb
Loaded weight: 6,612lb
Max speed: 110.5mph
Climb Rate: 33min 20sec to 9,843ft
Service ceiling: 13,287ft
Endurance: 6hr 30min
Armament: Four 7.7mm machine guns - two fixed forward firing, one flexibly mounted dorsal gun, one flexibly mounted ventral gun
Bomb load: Two 275lb, three 132lb or three 66lb bombs