fuselage decking above the engine. Engines proved to be more of a problem. Vogt originally submitted the design mounting the new BMW XV. The future of this engine was in doubt, however, and the Reich Air Ministry (RLM) asked for the design to be resubmitted with the 485 kW (650 hp) Pratt & Whitney Hornet radial engine, then starting licensed production in Germany as the BMW 132. Vogt's team then modified the design to use the Hornet as Projekt 6a, or alternately the Rolls-Royce Kestrel as Projekt 6b. The RLM found the resulting design interesting enough to fund construction of three prototypes. The Hornet-powered Ha 137 V1 first flew in April 1935, followed the next month by the V2, and both were shipped to Travemünde that summer. It quickly became apparent that the Hornet engine was so large that visibility during diving was greatly affected, and the RLM then suggested that the third prototype be completed as a 6b with the Kestrel, delaying it slightly to change the engine mounts and add a somewhat odd-looking radiator under the nose. By this point the definitive requirements for the dive bomber program had been drawn up, taken directly from Junkers' description of its own entry which had already been selected to win, calling for a two-seater arrangement. The Ha 137 was thus excluded, although realistically no other design had a chance to win anyway. The RLM was nevertheless interested enough in the design to order another three prototypes with the new Junkers Jumo 210 engine. The radial-powered versions retroactively became known as the Ha 137A, while the inline-powered versions became the Ha 137B. Further testing continued during 1936, and the prototypes also took part in the "doomed" dive bomber contest in June 1936, but the design was still being considered for the close support role instead of dive bomber. However, when Ernst Udet took over the T-Amt later that year, he considered the close support role unnecessary, and informed Hamburger that it should stop work on the design. The three Jumo-powered prototypes were built anyway during 1936 and 1937, eventually being used as testbed aircraft at Blohm & Voss. V1 was destroyed in testing during 1935 when the ammunition for its guns exploded, and V6, D-IDTE, crashed in July 1937, but the remaining four were used for years until a lack of spare parts for their engines eventually grounded them. Vogt had