The Weserflug P.1003 is a double-seat vertical takeoff and landing (VTOL) aircraft designed by Weserflug Zeikbau in Germany in 1938. With the support of the German Ministry of Aviation, which was interested in military tiltrotor aircraft, this aircraft was developed with Dr. Adolf Rohrbach as the chief designer. The most distinctive feature of this aircraft is that the wings are rotated 90 degrees from the middle of the wing; the propeller is directly above, vertical takeoff is performed in the same way as a helicopter, and after takeoff, the main wings are gradually rotated to a horizontal state. This secures the driving force forward. The main wing is a high wing type to secure the clearance of the huge propellers, with a diameter of four meters. It was operated by one Daimler-Benz DB600 series engine mounted on the back of the cockpit, and the air intake was the bottom of the nose. The landing gear was retractable to the fuselage, and the cockpit had a tandem arrangement for two passengers in the front and rear seats. The P.1003 was a novel concept, but there was no prospect of developing a complicated power transmission mechanism that operated the propellers at both wingtips with one engine, so a prototype was never built.