In stiff competition with Oemichen, Spanish engineer Marquis Raul Pateras Pescara began building rotary wing machines, initially in Barcelona, but after 1922, in France. In June of that year, Pescara proposed a co-axial rotor aircraft where the rotors could stop and form a biplane. A pusher propeller provided forward thrust. He built a small-scale model of the concept, but nothing more. Interestingly, a concept not unlike this, the Herrick Convertoplane, was flown in the U.S. just 15 years later.