David Crighton was struck down by cancer in his fifty-eighth year. He was then
at the height of his career and was one of the most admired personalities in fluid
mechanics. He had specialized in wave theory, helping to understand and solve
problems of practical importance using the full power of mathematical method. Efforts
to control the sound and vibration caused by unsteady flow were never far from his
thinking, and Crighton's contribution to those efforts has changed significantly the
way the subject is viewed. Having first attracted him into the field and never losing
my interest in the way he was influencing it, it is natural that I should comment on
the technical developments while looking back on Crighton's professional life. The
subject has changed a great deal and there are now many more researchers involved in
its study, many of whom rely on techniques that Crighton pioneered – really powerful
mathematical methods. But the basic problems remain: powerful flows are noisy.