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a CER — ee Above left: Snyder and Hoffman produced a number of advanced designs to succeed S-4, but they were never built. via Bill Rose dt ae ica Above right: This twin-engine design was completed by Cloyd Snyder in the late 1930s, but it was never built. Notable similarities between this concept and the later work of Charles Zimmerman are apparent. via Bill Rose Right: Dr Louis Crook designed this ducted propulsion monoplane. It was completed in 1942 and kept secret until after World War Two. US Patent Office By the late 1930s Crook had undertaken a series of largely theoretical design studies using ducted fan propulsion and he clearly appreciated the way that internal space could be fully utilised in a heel-shaped aircraft. However, these were essentially research papers and his drawings showed no provi- sion for a cockpit, payload or undercarriage. The work was completed in 1942 and appears to have been classified as ‘Secret’ until the end of the war, but there can be little doubt that Crook’s studies on low aspect ratio aircraft proved influential. Johnson’s Uni-Plane Richard Burton Johnson had been interested in aviation throughout his school years and in 1931 he started attending an evening course in aerodynamics at the Chicago Aeronautical University. As part of his project Johnson was encouraged to design a small aircraft, which he called the Centricopter. He was especially interested in the idea of VTOL or STOL and conceived a circular-winged aircraft with a central rotor to generate lift. Johnson may have built a scale model of his monoplane design, but he soon aban- Filed Feb. 19, 1942 19 Early Circular-Winged Aircraft