11/15/2020. Remarks by Johan Visschedijk: "Having acquired the manufacturing rights for the Douglas DC-2, in 1935 Nakajima undertook at Ota the design of a smaller twin-engined aircraft for use on short-range light traffic routes. Engineer Akegawa was assigned the responsibility of designing the aircraft then known as the Nakajima Aerial Transport No. l, or AT-1, and took his inspiration from the Douglas DC-2 and General Aviation GA-43.
During its design the aircraft was extensively modified and when completed in 1936 was designated Nakajima AT-2, the letter A then standing for Akegawa, the chief engineer's name. The AT-2 was of all-metal construction with fabric covered control surfaces, and accommodated a crew of three and eight passengers in an enclosed cabin.
Powered by two 580 hp Nakajima Kotobuki 2-1 nine-cylinder air-cooled radials driving fixed-pitch two-blade propellers, the prototype was first flown on September 12, 1936, from Ojima Airfield, near Ota. During its tests the aircraft was flown by pilots from the manufacturer, Japan Air Transport Co, Manchurian Air Transport Co., the Japanese Civil Aeronautics Authority and the two military Services.
The AT-2 demonstrated excellent performance and was quite stable, but minor problems arose with engine cooling, equipment and landing gear retraction mechanism. These deficiencies were corrected on the production machines and, powered by two 650 hp Nakajima Kotobuki 41 engines, 32 aircraft were built between 1937 and 1940 for Dai Nippon Koku K.K. (Greater Japan Air Lines Co. Ltd.) and Manchurian Airlines Co. with which they served until the end of the war.
In 1937, the aircraft was also adopted by the IJAAF as a communication and paratroop transport aircraft and the Army machines were designated Army Type 97 Transport or Ki-34. Powered by two 650 hp Nakajima Ha-1b engines enclosed in smooth NACA-type cowlings similar to those fitted to late production civil AT-2s, nineteen Ki-34s were built by Nakajima between 1937 and 1940. However, more Ki-34s were manufactured by Tachikawa Hikoki K.K. which delivered 299 between 1939 and 1942.
Some Ki-34s were handed over to the IJN and were designated Navy Type AT-2 Transport (Nakajima L1N1) by that Service. The allied code name "Thora" was applied to the military and civil machines alike.
