Reflections on Professor Kurt Hohenemser's Pioneering Contributions to Helicopters and Wind Turbines

This paper presents a historical account of Professor Kurt Hohenemser's contributions to the theory and development of helicopters and wind turbines for nearly 65 years---with Anton Flettner from 1935 to 1945, then at McDonnell Aircraft Co. from 1947 to1965, and finally at Washington University in St. Louis from 1965 through his passing in 2001. For completeness, this paper also covers in passing his teaching and research at Göttingen University under Lüdwig Prandtl from 1930 to 1934 and his pursuit of environmental issues from 1975 to 2001. Among the several helicopter designs for which Hohenemser was instrumental, the Flettner synchropter Fl 282 (1940) --- the world's first production helicopter--- and the McDonnell compound helicopter XV-1 (1954)---one of the first experimental compound helicopters---stand out. At Washington University in St. Louis, he made fundamental contribution to flap-lag stability, dynamic inflow and Floquet theory, and his work on multiblade coordinates is considered a milestone in aeromechanics; there he also pioneered research on random gust response, and conducted theoretical and experimental work on wind-energy conversion. He served JAHS as its Editor-in- Chief twice: from 1962 to 1963, and also from 1975 to 1976. His accolades include the AHS Honorary Fellow Award (1953), the AIAA Grover E. Bell award (1957), the AHS Alexander Klemin Award (1963) and the ASME spirit of St. Louis medal (1985).