Kawanishi H6K. (飛行艇) Mavis ("Songbird"). The all-metal long-range four-engine flying boat "97" of the Imperial Japanese Navy was developed by Kawanishi under the leadership of Shizuo Kikuhara. The first prototype of the H6K1 flying boat was manufactured by July 1936, and on July 14, Kawanishi test pilot Katsui Kondo took it into the air. Flight tests confirmed the expectations of the designers, and on July 25, 1936, the aircraft was handed over to the customer.
Structurally, the aircraft was a four-engine all-metal upper wing with a "parasol" -type wing attached to the fuselage by means of inverted V-shaped struts and struts. As a power plant, the developers chose the Nakajima Hikari 2 engines with a capacity of 840 hp. from. The H6K1's twin-run fuselage was similar in design to . Japanese designers sent to Great Britain to the aircraft building firm "Short Brothers" "took out" all the best from there and did not "reinvent the wheel" in their homeland. A characteristic feature of the new aircraft was the use of an unusually large aspect ratio and span. This made it possible to accommodate six fuel tanks in the wing with a total capacity of 7765 liters. On subsequent modifications of the H6K4, the capacity of the fuel tanks reached 13409, which made it possible to achieve an impressive range.
Power plant. As a power plant, the developers chose Nakajima Hikari 2 engines with a capacity of 840 hp, but their power was insufficient. Problems with the insufficient power of the power plant were solved by installing more powerful engines of 14-cylinder air-cooled Mitsubishi MK8D Kinsei 45 engines with a capacity of 1000 hp, rotating three-blade propellers with variable pitch with a diameter of 5.2 meters. The H6K5 Model 23 was powered by even more powerful Mitsubishi Kinsei 51 or 53 engines with 1,300 hp. s, while the power of the power plant was 5200 liters. from.
Armament H6K5. Four 7.7 mm type 92 machine guns in the nose and upper turrets and two side blisters, one 20 mm type 99 model 1 cannon in the tail turret (three 7.7 mm machine guns on front turret, top and rear turrets); 2 × 800 kg of torpedoes or up to 1000 kg of bombs.
Combat use. At first, the effectiveness of the actions of flying boats of this type as bombers was very high, but then, in the face of increased opposition from the enemy, it began to decline. Due to the lack of reservations for crew jobs and protection of fuel tanks, H6K aircraft became easy prey for Allied fighters, so they soon ceased to perform such tasks. But as a long-range reconnaissance, when the probability of meeting with enemy fighters was small, flying boats operated very successfully. In the vast expanses of the Pacific Ocean, the long flight duration of the H6K came in handy. Beginning in the second half of 1942, the Mavis began to be ousted from parts of the first line by the more advanced N8K boats. Releasing machines were transferred to perform tasks of patrolling the oceanic expanses. At least three H6K boats at the turn of 1942-1943 were equipped with search radars (first used in the Imperial Japanese Air Force).
The Allied flying boats received the code designation "Mavis" ("Songbird"). In total, in 1938-1942, 215 H6K flying boats of all modifications were produced.