In 1932, the Imperial Japanese Navy raised a specification for a long-range floatplane reconnaissance aircraft to replace its Yokosuka E1Y and E5Y operating from its seaplane tenders and battleships, requesting prototypes from Aichi and Kawanishi. Aichi's entry, the Aichi AB-6 or Aichi Experimental 7-Shi Reconnaissance Seaplane, designed by Tetsuo Miki, was based on the Heinkel He 62, one example of which had been imported by Aichi the previous year for evaluation against a similar requirement. The AB-6 was a biplane with folding wings for storage aboard ship, of all-metal construction with fabric covering, and powered by a single Hiro Type 91 W12 engine. Its crew of three, pilot, observer and radio operator/gunner were accommodated in an enclosed cockpit.[1]
The prototype was completed in February 1933 and made its maiden flight from Nagoya harbor. While it had good handling in the air, its speed, take-off, and landing performance was disappointing, and the aircraft was modified to try to improve matters. It was fitted with revised wings, of different aerofoil section and with full-span leading edge slats. The original Hamilton-Standard two-bladed metal variable-pitch propeller was first replaced by a two-bladed wooden propeller and then a four-bladed wooden unit. Despite these changes, Kawanishi's design remained superior, and in 1934, was ordered into production as the Navy Type 94 Reconnaissance Seaplane, or Kawanishi E7K.[2] [3]