Sir William Rede Hawthorne. 22 May 1913—16 September 2011

William Rede Hawthorne was a pioneer in gas turbine aerodynamics and thermodynamics, a sought-after technology advisor to industry and government, and a generous and enthusiastic teacher who encouraged students to excel. His outstanding contributions included resolution of combustion problems that limited the operation of the original Whittle jet engine, early in-depth descriptions of compressible channel flow that still inform engineers today, innovative and wide-ranging analyses of secondary flows in turbomachinery that defined the field, and creation of some of the first notes on gas turbine cycle analysis. A theme in the many areas of engineering in which he had impact was the satisfaction from the growth of understanding that can accompany making things work—in his words, ‘machines produce ideas just as surely as ideas produce machines’. A Cambridge graduate, he was a professor at MIT when, in 1951, he was recruited to a newly established chair at Cambridge, where he later had leadership roles as head of the engineering department (1968–73) and Master of Churchill College (1968–83). He retained strong ties to MIT, however, and fostered lasting collaborations between the two universities. Among his numerous awards and honours were the US Medal of Freedom (1947), a Royal Society Medal (1982) and a knighthood (1970) for ‘services to thermodynamics’, a citation that pleased him greatly.