In 1935, the RLM (Reichsluftfahrtministerium, Reich Aviation Ministry) invited tenders from several companies for a new Luftwaffe aircraft suitable for liaison, army co-operation (today called forward air control), and medical evacuation. This resulted in the Messerschmitt Bf 163 and Siebel Si 201 competing against the Fieseler firm's tender. Conceived by chief designer Reinhold Mewes and technical director Erich Bachem, Fieseler's design had a far better short take off and landing ("STOL") performance. A fixed slat ran along the entire length of the leading edge of the long wings, while a hinged and slotted set of control surfaces ran along the entire length of trailing edge. This was inspired by earlier 1930s Junkers Doppelflügel, "double-wing" aircraft wing control surface design. For the Fi 156, this setup along each wing panel's trailing edge was split nearly 50/50 between the inboard-located flaps and outboard-located ailerons, which themselves included trim tab devices over half of each aileron's trailing edge length.