The outbreak of the Second World War shaped Austyn Mair's life. Working in the aero-engine department of Rolls-Royce in Derby at the time, he was commissioned in the RAF and sent to the Royal Aircraft Establishment (RAE) at Farnborough. There he spent the rest of the war working on the design and commissioning of wind tunnels, testing model aircraft and investigating their performance in the race to keep ahead of German technical developments.

He also made measurements on fighter planes flown by test pilots, including captured reconstructed enemy aircraft. In the early summer of 1945 he was sent to Germany to discover what developments had been made there in aircraft and rocket technology. At the end of the war he transferred his experimental investigations to the academic world, firstly at Manchester and then Cambridge.

William Austyn Mair was born in 1917 and educated at Highgate School, London, and Clare College, Cambridge, taking a first with distinction in the mechanical sciences tripos. After a short period at Rolls-Royce, Derby, he was commissioned in the RAFVR and transferred to the Technical Branch of the RAF.

At Farnborough, under Alexander Thom, his work was centred on the problems of aerodynamics at speeds approaching the speed of sound. He assisted Thom with the design and commissioning of the RAE's first large wind tunnel designed for high subsonic speeds. He also worked on the design of a large low-speed tunnel and on small wind tunnels for the study of aircraft icing.

The knowledge gained from wind tunnel tests of aircraft and component models at high speed was used by Mair in a revised aerodynamic design of nacelles for the Gloster Meteor, the RAF's first operational jet aircraft, which added considerably to its speed. At that time the behaviour of aircraft flying near and above the speed of sound was not well understood. When diving at high speeds the Spitfire experienced changes of trim and buffeting. Mair devised instruments for measuring the loads on the tailplane and these changes of trim. At the end of the war he edited the monograph describing the research on high-speed aircraft at the RAE.

Demobilised as a squadron leader in 1946, after a few more months at Farnborough, he was appointed to a readership and the directorship of the new Fluid Motion Laboratory at the University of Manchester. There were no facilities and equipment, but an aircraft hangar was leased, and a supersonic wind tunnel and a low-speed, low-turbulence wind tunnel were built. Research on various aspects of supersonic flow was carried out.

In 1952 Mair succeeded Sir Melvill Jones as Francis Mond Professor of Aeronautical Engineering at Cambridge. He was only 35. The aeronautics laboratory then comprised three small low-speed wind tunnels in a small wooden hut. Mair set to work to design and build a supersonic wind tunnel and a larger low-speed wind tunnel. By 1960 the new aerodynamics laboratory was in full use.

A light aircraft kept at Marshalls airport in Cambridge was modified so that suction could be applied to the wings, thereby greatly delaying separation and reducing the stalling speed. In addition to work on supersonic flow, he developed an interest in the low-speed flow past bluff bodies.

In 1961 Mair was appointed a director of Hovercraft Development Ltd, a subsidiary of the National Research Development Corporation. The study of hovercraft problems led to work on the wind forces on a tracked hovercraft and conventional trains in a cross-wind.

In 1973 Mair became head of the engineering department at Cambridge, in an economic recession brought about partly by the oil embargo and price increase. His quiet but positive style suited a period of pruning and consolidation, and he was reappointed as head of the department for another five years from 1978. During his period of office several new professors of engineering were appointed, raising the number to 12, and the teaching and examinations were modified and laboratory facilities improved and modernised. In the late 1970s a new four-year course for the production engineering tripos, later known as the manufacturing engineering tripos, was introduced under his leadership.

In 1966 he gave the Lanchester Lecture to the Royal Aeronautical Society on “Short Take Off and Landing Aircraft” and in 1975 was awarded the society's Silver Medal. He served on the Aeronautical Research Council and was on the editorial board of the Aeronautical Quarterly, which he also chaired.

He was appointed CBE in 1969, elected to the fellowship of engineering (later the Royal Academy of Engineering) in 1984 and awarded an honorary DSc by the Cranfield Institute of Technology in 1990. He was a Fellow of Downing College from 1953 and was elected an honorary Fellow in 1983. In retirement he worked as an engineering consultant, and published a book, Aircraft Performance (with D.L. Birdsall).

Whether in RAF uniform or on his Cambridge bicycle Mair could seem aloof at first, but his qualities of straightforwardness and fairness made him much liked and respected by all his colleagues.

He is survived by his wife, Mary, whom he married in 1944, and by their two sons, one of whom is Professor of Engineering at Cambridge and Master of Jesus College.

Professor Austyn Mair, CBE, Professor of Aeronautical Engineering, University of Cambridge, 1952-83, was born on February 24, 1917. He died on January 17, 2008, aged 90