Dornier Do 24 The Dornier Do 24 is a 1930s German three - engine flying boat designed by the Dornier Flugzeugwerke for maritime patrol and search and rescue . According to Dornier records , some 12 , 000 people were rescued by Do 24s during its flying career . A total of 279 were built among several factories from 1937 - 1945 . Design and development . The Dornier Do 24 was designed to meet a Dutch navy requirement for a replacement of the Dornier Wals being used in the Dutch East Indies , with the Netherlands government signing a contract for six Dornier Do 24s on 3 August 1936 . Two more prototypes were built for the German navy to be evaluated against the Blohm & Voss BV 138 . The Do 24 was an all - metal parasol monoplane with a broad - beamed hull and stabilising sponsons . Twin tail s were mounted on the upswept rear of the hull , while three wing - mounted tractor configuration engines powered the aircraft . Fuel was carried in tanks in the sponsons and the wing centre section . Up to of bombs could be carried under the aircraft ' s wings , while defensive armament consisted of three gun turrets , one each in nose , dorsal and tail positions . In early aircraft the turrets were fitted with a single machine gun each , but later aircraft carried a 20 mm cannon in the dorsal turret . " Do 24 V3 " , the first of the Dutch boats , took off from Lake Constance on 3 July 1937 , with the second Dutch boat , " Do 24 V4 " following soon after . As the Dutch required that their flying boats use the same engines as the Martin 139 bombers in use in the Dutch East Indies , they were fitted with Wright R - 1820 - F52 Cyclone radial engines . Test results were good , with the new flying boat proving capable of operating from extremely rough open seas , and the Dutch placed an order for a further 12 Do 24s on 22 July 1937 . " Do 24 V1 " , the first of the two aircraft for Germany , powered by three Junkers Jumo 205 C diesel engines , flew on 10 January 1938 , but after evaluation , the two German boats were returned to Dornier for storage . The Netherlands was enthusiastic about the new flying boat , and planned to purchase as many as 90 Do 24s . Of these , 30 were to be built by Dornier ( with all but the first two prototypes assembled by Dornier ' s Swiss subsidiary based at Altenrhein ) . The remaining aircraft were to be built under licence in the Netherlands by Aviolanda at Papendrecht . Of these aircraft , all but one of the German and Swiss built aircraft and the first seven Aviolanda - built aircraft were to be Do 24K - 1s , powered by the original R - 1820 - F52 engines , while the remaining aircraft were to be Do 24K - 2s , with more powerful R - 1820 - G102 engines and more fuel . Only 25 aircraft had been built on the Aviolanda assembly line before the German occupation . The " Luftwaffe " were interested in the completed and partially completed aircraft . The Dutch production line continued to produce aircraft under German control . 11 airframes were completed with Dutch - bought Wright Cyclone engines , but later models used the BMW Bramo 323 R - 2 . A further 159 Do 24s were built in the Netherlands during the occupation , most under the designation Do 24T - 1 . Another production line for the Do 24 was established in the old CAMS factory at Sartrouville , France , during the German occupation . This line was operated by SNCAN and was able to produce another 48 Do 24s . After the liberation , this facility produced a further 40 Do 24s , which served with the French Navy until 1952 . Operation history . Thirty - seven Dutch - and German - built Do 24s had been sent to the East Indies by the time of the German occupation of the Netherlands in June 1940 . Until the outbreak of war , these aircraft would have flown the tri - color roundel . Later , to avoid confusion with British or French roundels , Dutch aircraft flew a black - bordered orange triangle insignia . A Dutch Dornier Do 24 is credited with sinking the Japanese destroyer " Shinonome " on December 17 , 1941 while the ship was escorting an invasion fleet to Miri in British Borneo . On 10 January 1942 a Dutch Dornier Do 24K spotted a Japanese invasion fleet heading for Tarakan Island in Dutch Borneo , giving adequate warning so that all oil installations could be destroyed before the Japanese arrived . After the Japanese invasion of the Netherlands East Indies , six surviving Do . 24s were transferred to the Royal Australian Air Force in February 1942 . They served in the RAAF through most of 1944 as transports in New Guinea , making the Do . 24 one of the few aircraft serving operationally on both sides during World War II . During the war , a German Do 24 made a forced landing in neutral Sweden , was impounded and eventually bought , and remained in Swedish service until 1952 . In 1944 , 12 Dutch - built Do 24s were delivered to Spain with the understanding that they would assist downed airmen of both sides . After the war , a few French - built Do 24s also found their way to Spain . Spanish Do 24s were operational at least until 1967 , and possibly later . In 1971 , one of the last flying Spanish Do 24s was returned to the Dornier facility on Lake Constance for permanent display . Survivors . Four complete aircraft survive :