Junkers Ju 87 turned to the designs of Herman Pohlmann of Junkers and co-designer of the K 47, Karl Plauth. During the trials with the K 47 in 1932, the double vertical stabilisers were introduced to give the rear gunner a better field of fire. The main, and what was to be the most distinctive, feature of the Ju 87 was its double-spar inverted gull wings. After Plauth's death, Pohlmann continued the development of the Junkers dive bomber. The Ju A 48 registration D-ITOR, was originally fitted with a BMW 132 engine, producing 450 kW (600 hp). The machine was also fitted with
Junkers J 2 spin on 23 September 1916 in one of the J 2s, and this event, combined with the substandard climbing performance of the J 2 series of test aircraft, caused "IdFlieg" to withdraw any further governmental support (effectively ending the J 2's contract) for the Junkers firm's advanced monoplane designs until a lighter metal, such as duralumin, was selected for such designs. The first attempt to use duralumin for airframe construction by the Junkers firm was the never-completed J 3 mid-wing, rotary engine-powered, aluminum tubing fuselage single-seat monoplane design, of which only the corrugated sheet duralumin-covered wing structures and "bare" tubular