The Aichi H9A flying boat was the only dedicated flying boat trainer to be placed into production in significant numbers during the Second World War.
In January 1940 Aichi were asked to produce a twin-engined flying boat train to be used by crews of the Kawanishi H8K1. A team led by Morishige Mori produced a parasol winged monoplane with two wings carried in nacelles built into the lower part of the wings and braced to the fuselage by N struts. It had semi-retractable tricycle beaching gear with the rear wheels level with the wing trailing edge. It carried a crew of five (pilot, co-pilot, observer, flight engineer and radio-operator) and with space for another three students. It could carry two flexibly mounted 7.7mm machine guns (one in the bow and one in a dorsal position) and two 551lb depth charges, partly for training purposes and partly so it could be used as an anti-submarine patrol aircraft.
The H9A had a metal structure and a mix of light alloy, plywood and fabric coverings.
The first prototype made its maiden flight in September 1940, and revealed some problems with the type's flight characteristics and during landings. Two more prototypes were developed, with the wings moved lower down, larger wings and modified flaps. These solved the handling problems and the type was ordered into production as the Navy Type 2 Training Flying Boat Model 11. Aichi built 3 prototypes in 1940 and 24 production aircraft in 1942-43. Nippon Hikoki K.K. built another four in 1944.
For most of the Second World War the H9A was used purely as a training aircraft, and it was so obscure that it never received an Allied code name (and most books use the same photo of the type in flight). Towards the end of the war a few of the aircraft were pressed into service on anti-submarine patrols around the Japanese coast.
Engine: Two Najajima Kotobuki 42 or 43 nine-cylinder air-cooled radials
Power: 710hp at take off, 610hp at 9,845ft each
Crew: 5 + 3 students
Span: 78ft 8 7/8in
Length: 55ft 7 5/16in
Height: 17t 2 11/16in
Empty weight: 10,803lb
Loaded weight: 15,432lb
Maximum weight: 16,525lb
Max speed: 197mph at 9,845ft
Climb Rate: 11min 14sec to 9,845ft
Service ceiling: 22,245ft
Range: 1,335 miles
Armament: Two 7.7mm Type 92 machine guns, one at bow and one in dorsal position
Bomb load: 551lb bombs or depth charges