In 1928, the Navy sought interest from Aichi and Nakajima in developing a shipboard reconnaissance seaplane for catapult launching. Again, Aichi turned to Heinkel for the design, and imported the HD 56 that, when accepted, became the Type 90-1 Reconnaissance Seaplane. Nakajima's similar entries became the Type 90-2-1 and -2 Reconnaissance Seaplanes, and the joint Yokosuka/Kawanishi aircraft became the Type 90-3 Reconnaissance Seaplane. The Navy accepted the Aichi/Heinkel HD 56 design in 1931 as the best example of a catapult launched aircraft, being particularly impressed by its Wright Whirlwind engine. The overall structure was well built, having simple interplane struts without bracing wires, and a sound mixture of wood and metal throughout the structure. What the Navy did not like about this Heinkel design was that it had too short a range, and lacked the desired speed. Despite these shortcomings, it was accepted by the Navy in December 1931, but with the stipulation that corrective modifications were made.
To satisfy the Navy, Aichi's engineer Tetsuo Miki set about making the desired improvements. The much liked 200 hp Wright Whirlwind engine was replaced by a 300 hp Type 90 Tempu engine to avoid import problems and to improve performance with the higher power. The wing was reduced by 0.6 m (1 ft 11 3/4 in), which in turn reduced the wing area by 2.04 sq m (21.959 sq ft). The interplane struts and the struts from the lower wing to the floats were moved inward by 0.3048 m (1 ft) and the empennage span and the height were reduced by 0.4 m (1 ft 3 3/4 in) and 0.01 m (2 in) respectively. Other changes were made in the ailerons, floats, and cockpit combing, all in an attempt to improve performance.
Aichi's test pilots Kanekichi Yokoyama and Tanizo Amagai made the first test flight with the Aichi-built (3rd Type 90-1 Reconnaissance Seaplane) in August 1931 from the port at Nagoya. Follow-on aircraft were delivered to Naval operational units beginning in 1932. Type 90-1s were used in the early stage of the Sino-Japanese conflict aboard Jintsu-Class light cruisers. Others were used in various tests related to catapult-launching.
Because of the inferior speed and climb of the aircraft, operational service life was short, and their existence is hardly known, having been overshadowed by the more manoeuvrable Nakajima Type 90-2-2 Reconnaissance Seaplane. Only twelve Type 90-1 aircraft were built, and they were soon transferred to training units. Some were released to for civil flying.
Technical Data
Manufacturer: Aichi Tokei Denki KK (Aichi Watch and Electrical Co Ltd).
Type: Single-engined twin-float reconnaissance seaplane.
Crew (2): Pilot and observer/gunner in open cockpits.
Powerplant: (Heinkel HD 56) One 200-220 hp Wright J-6 Whirlwind nine-cylinder air-cooled radial engine, driving a two-blade wooden propeller, (Type 90-1) One 300-340 hp Type 90 (Gasuden) Tempu nine-cylinder air-cooled radial engine, driving a two-blade wooden propeller.
Armament: One fixed forward-firing 7.7 mm (0.303 in) machine-gun and one flexible 7.7 mm (0.303 in) machine-gun in open dorsal cockpit. Bomb load: Two 30 kg (66 lb) bombs.
Dimensions: Span (HD 56) 11.70 m (38 ft 4 1/2 in), (Type 90-1) 11.10 m (36 ft 5 in); length (HD 56) 8.50 m (27 ft 10 1/2 in), (Type 90-1) 8.45 m (27 ft 8 3/4 in); height (HD 56) 3.50 m (11 ft 6 in), (Type 90-1) 3.67 m (12 ft); wing area (HD 56) 38 sq m (409.041 sq ft), (Type 90-1) 34.5 sq m (371.367 sq ft).
Weights: Empty (HD 56) 993 kg (2,189 lb), (Type 90-1) 1,118 kg (2,464 lb); loaded (HD 56) 1,500 kg (3,307 lb), (Type 90-1) 1,600 kg (3,527 lb) wing loading (HD 56) 39.5 kg/sq m (8.09 lb/sq ft), (Type 90-1) 46.3 kg/sq m (9.483 lb/sq ft); power loading (HD 56) 7.5 kg/hp (16.5 lb/hp), (Type 90-1) 5.33 kg/hp (11/7 lb/hp).
Performance: Maximum speed (HD 56) 90 kt (104 mph) at sea level, (Type 90-1) 107 kt (123 mph) at sea level; cruising speed (HD 56) 63 kt (72.5 mph) at 500 m (1,640 ft), (Type 90-1) 67.5 kt (77.6 mph) at 500 m (1,640 ft); minimum speed (HD 56) 37 kt (42.5 mph), (Type 90-1) 41 kt (47 mph); Climb to 3,000 m (9,843 ft) (HD 56) in 24 min 30 sec, (Type 90-1) in 18 min 18 sec; service ceiling (HD 56) 3,270 m (10, 728 ft), (Type 90-1) 4,710 m (15,452 ft); range (HD 56) 296 nm (340 miles), (Type 90-1) 407 nm (468 miles); endurance (HD 56) 4.7 hr, (Type 90-1) 6 hr.
Production: A total of 12 E3A1s were built as follows:
Ernst Heinkel Fluzeugwerke:
1 - prototype 1929
Aichi Tokei Denki KK:
2 - prototypes & 9 production aircraft - 1930-1932.
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