Junkers Ju 87 late 1934. It was to have been completed in April 1935, but, due to the inadequate strength of the airframe, construction took until October 1935. The mostly complete Ju 87 V1 W.Nr. 4921 (less non-essential parts) took off for its maiden flight on 17 September 1935. The aircraft was later given the registration D-UBYR. The flight report, by "Hauptmann" Willy Neuenhofen, stated the only problem was with the small radiator, which caused the engine to overheat. The Ju 87 V1, powered by a Rolls-Royce Kestrel V12 cylinder liquid-cooled engine, and with a twin tail, crashed on 24 January 1936 at
Junkers marked on the J-9's landing gear wheel covers. The corrugated duralumin wing and fuselage "skin" introduced in the J-series became a trademark of Junkers aircraft built in the 1920s and '30s. Development continued during the course of World War I, including a growing (but troublesome) partnership with Fokker, as the "Junkers-Fokker Aktiengesellschaft". Several Junkers designs were licensed to Fokker during this period. The visual similarity of Junkers and Fokker aircraft during the next decade, especially after Reinhold Platz adapted some of the Junkers design concepts, but mostly crafted in wood for the Fokker designs' wing structures instead of the all-metal