Kawanishi H6K Mavis
The Kawanishi H6K was a four-engined maritime patrol flying boat built by the Kawanishi Aircraft Company for the Imperial Japanese Navy, which designated it the Type 97 Large Flying Boat; the Allies knew it as "Mavis". First flown on 14 July 1936 and in service from January 1938, it was built for very long patrols over the Pacific and served from the Sino-Japanese War through the whole Second World War as a patrol, bombing and transport aircraft, while civil examples carried mail and passengers for Japan's national airline. Production totalled 215 aircraft; in front-line service the type was replaced by the Kawanishi H8K.
Why It Mattered
The H6K was the Imperial Japanese Navy's Type 97 Large Flying Boat, its long-range maritime patrol aircraft at the start of the Pacific War. For the Smithsonian, aircraft such as the H6K embodied the 1930s ambition to showcase national prowess through transoceanic airline service. Its endurance was its strength: an H6K4 could stay airborne for almost 27 hours at a time. Japan's airline routes were closely tied to military goals, the Smithsonian notes, and the H6K, chosen for that service, became a patrol bomber in the Second World War. Despite having no armour or self-sealing fuel tanks, it remained in front-line service throughout the Second World War.
Design Notes
Kawanishi answered the Navy's revised specification with its Type S, a parasol-wing, four-engined flying boat with its hull suspended beneath the wing. The design drew on British flying-boat practice: Kawanishi had licence-built the Short Rangoon as the Kawanishi H3K. History of War calls its resemblance to the Sikorsky S-42 remarkable; that resemblance led the Allies to consider the H6K a copy of the American boat, though History of War notes the two differed beyond their basic shape. Early water handling was flawed; moving the forward step back by 50 cm improved it, and later prototypes were built with Mitsubishi Kinsei 43 engines. It carried a crew of nine. In the H6K4, the main production version, endurance reached almost 27 hours.
Operational History
The H6K entered Navy service in January 1938 and made its combat debut during the Sino-Japanese War. Production, centred on Kawanishi's plant at Naruo, totalled 215 aircraft of all versions, among them 127 H6K4s and 36 H6K5s. By the beginning of the Second World War, 66 examples had been provided to the Navy. From New Guinea and the Netherlands East Indies it flew long bombing missions, among them the attack on 4 January 1942, when eleven H6K4s bombed the airfield at Vunakanau, Rabaul. Those bombing operations were abandoned as Allied fighters exploited the type's lack of armour or self-sealing fuel tanks, but it continued to operate as a maritime reconnaissance aircraft over the Pacific. Alongside the patrol versions, Kawanishi built unarmed transports, sixteen H6K2-Ls, and sixteen aircraft were flown by Japan's national flag carrier on mail and passenger services.
Afterlife
The H6K remained in active service through to the Surrender of Japan. In front-line service it was replaced by the Kawanishi H8K Emily. A single H6K5 was restored to flight by British and Indonesian forces during the Indonesian War of Independence. No complete H6K survives anywhere today. What is left is wreckage: an H6K sunk in Makin Lagoon in September 1943 was dived in 1992, when its radio was recovered and its 20 mm Type 99 cannon was recovered and restored.