Disagreements regarding the requirements to be met by the new reconnaissance float seaplane prevented the manufacturers from submitting specific designs. However, in October 1940, Engineers Kishiro Matsuo and Yasushiro Ozawa at Aichi Kokuki K.K. in Eitoku began designing the Aichi AM-22 and in January 1941 the Navy drafted a new 16-Shi (1941) specification around the design of the AM-22. Requirements were once again modified in July 1941 but after that date the Aichi design was finalized.
The first Aichi AM-22, officially designated Navy Experimental 16-Shi Reconnaissance Seaplane (E16A1), was completed in May 1942. Except for wooden wing tips and tail plane and fabric covered control surfaces, the aircraft was of all-metal construction and was powered by an 1,300 hp Mitsubishi MK8A Kinsei 51 radial and armed with two wing-mounted 0.303 in (7.7 mm) machine guns and one flexible rear-firing 0.303 in (7.7 mm) machine gun. The twin single-step metal floats were attached to the wings by vertical N-struts and to the fuselage by inclined I-struts.
The wings folded upward for stowage aboard cruisers or seaplane tenders. Designed to operate as a dive-bomber, the E16A1 was fitted with hydraulically-operated dive brakes mounted on the front leg of the N-struts. Two additional prototypes with wing span increased from 41 ft 8 in (12.70 m) to 42 ft 0.3 in (12.81 m) were built and were used to test various dive-brake designs as the original set caused excessive buffeting when extended. Like the production aircraft these prototypes were armed with two wing-mounted 0.787 in (20 mm) cannon and one flexible 0.511 in (13 mm) machine gun and could carry one 250 kg (5511b) bomb under the fuselage.
With perforated dive brakes, redesigned rear canopy section, strengthened floats and improved flap actuation mechanism the E16A1 was accepted for production in August 1943 as the Navy Reconnaissance Seaplane Zuiun (Auspicious Cloud) Model 11. Early production aircraft were powered by the Mitsubishi MK8A Kinsei 51 radial, but this engine was replaced by the MK8D Kinsei 54 on late production aircraft, most of these being built by Nippon Hikoki K.K. The E16A2, powered by a 1,560 hp Mitsubishi MK8P Kinsei 62, was still undergoing tests at the time of the Japanese surrender.
Entering service at a time when Japan had lost air superiority, the E16A1s (code name Paul) suffered heavy losses during the Philippines campaign of 1944 and most surviving Zuiuns were expended in suicide attacks in the Okinawa area. A total of 256 E16As were built, of which Aichi produced the 3 E16A1 prototypes, 193 production E16A1s and 1 E16A2 prototype, the balance of 59 E16A1s was built by Nippon Hikoki K.K. at Tomioka.
The pictured aircraft belonged to the 634th Kokutai and the non-airworthy aircraft was brought to the USA as a war prize aboard the US Core. It arrived at NAS Patuxent River, Maryland, and via NAS Norfolk, Virginia it ended up in a display at Floyd Bennett Field. The aircraft was also pictured without USAAF markings.
Description: Single-engined twin-float reconnaissance seaplane. All-metal structure with stressed-skin covering, wooden wing tips and tail plane, and fabric covered control surfaces.
Accommodation: Crew of two in tandem enclosed cockpits.
Power plant:
E16A1 prototypes and early production: one Mitsubishi MK8A Kinsei 51 fourteen-cylinder air-cooled radial, rated at 1,300 hp for take off, 1,200 hp at 9,843 ft (3,000 m) and 1,100 hp at 20,340 ft (6,200 m), driving a three-blade constant-speed metal propeller.
E16A1 prototypes and late production: one Mitsubishi MK8D Kinsei 54 fourteen-cylinder air-cooled radial, rated at 1,300 hp for take off, 1,200 hp at 9,843 ft (3,000 m) and 1,100 hp at 20,340 ft (6,200 m), driving a three-blade constant-speed metal propeller.
E16A2 prototype: one Mitsubishi MK8P Kinsei 62 fourteen-cylinder air-cooled radial, rated at 1,560 hp for take off, 1,340 hp at 6,890 ft (2,100 m) and 1,190 hp at 19,030 ft (5,800 m), driving a three-blade constant-speed metal propeller.
Armament:
First prototype: two wing-mounted 0.303 in (7.7 mm) Type 97 machine guns, one flexible rear-firing 0.303 in (7.7 mm) Type 92 machine gun and external bomb load of 397 lb (180 kg).
All aircraft except first prototype: two wing-mounted 0.787 in (20 mm) Type 99 Model 2 cannon, one flexible rear-firing 0.511 in (13 mm) Type 2 machine gun and an external bomb load of 551 lb (250 kg).