Career
After World War I Fonó returned to the subject of jet propulsion, in May 1928 describing an "air-jet engine" (now called a ramjet) which he described as being suitable for high-altitude supersonic aircraft, in a German patent application. In an additional patent application he adapted the engine for subsonic speed. The patent was finally granted in 1932 after four years of examination (German Patent Number 554,906, 1932-1911-02).
Finally, in 1960, the American Rocket Society reviewed his patents and acknowledged him as the inventor of the jet engine.
He is remembered by the Albert Fonó Award, which is awarded by the Hungarian Astronautical Society.