Junkers G-38 – Germany’s Enormous Transport.
At the end of the twenties Hugo Junkers returned to his idea of a large scale transport aircraft. Initial steps toward this direction were already made in the early twenties with the JG1, which had to be destroyed following the demand of the Allied forces.
In 1927 Junkers and Zindel started with the design of postal seaplane under the designator J-40 for transatlantic missions. A landplane version was developed under the designator J-38. The German Navy was interested in the seaplane design, but finally Junkers led the developement towards the landplane version.
The assembly of this J-38 took more than two years. On November, 6th 1929 Junkers pilot Zimmermann flew the G-38 first. This G-38 was used for extensive demonstration flights during 1930. On April 10th 1930 Zimmermann and Schinzinger achieved several world records with the G-38 with a payload of 5000kg at Dessau.
In November 1930 the G-38 performed a Europe round trip, which finished the flight tests of the G-38. In July 1931 the G-38 prototype was delivered to Lufthansa.
A second and final G-38 was built during 1932. Both aircraft were used by Lufthansa on its Berlin-London routes during the following years.
The Junkers G-38 was the largest landbased aeroplane at the end of the twenties.
Following the successful test flights of the G-38 Junkers advised Zindel to develop a special G-38 for military purposes under the designator K-51. Already in 1928 Mitsubishi from Japan showed interest in the G-38 design and asked Junkers for a heavy bomber design, which finally led to the K-51 concept.
In April 1930 a license agreement was signed between Junkers and Mitsubishi for the K-51 production in Japan. A Junkers team went to Japan during that time and supported Mitsubishi with the further development. Parts for the first two prototypes were manufactured at Dessau and delivered to Japan.
In 1931 the first Ki-20, as the aircraft was called in Japan. A further four Ki-20 were built until 1935. These serial line aircraft were built with Japanese components and therefore showed slight differences to the G-38. Like the German G-38s of Lufthansa, the Japanese Ki-20s underwent several engine changes. The Ki-20 was used until the beginning of WWII as a heavy bomber aircraft by the Japanese forces.