I felt indeed very honoured when I was invited to deliver the 30th Lanchester Memorial Lecture. I immediately started reading Frederick W. Lanchester's famous and impressive work ‘Aerodynamics’ published in 1907. It was very interesting to read but of course there was nothing to be found about delta wings at supersonic speeds, which I had offered to talk about, partly because I had studied this for the last 5–10 years and partly because Sweden had been developing delta winged military aircraft since 1948 or so. I also know of course that Great Britain had made impressive progress at the same time particularly Dietrich Küchemann and the group around him. I could therefore expect and fear to have a competent and critical audience to face.

Travellers flying into Paris would not connect the famous 100-year-old landmark, the Eiffel Tower, an immense and complex structure of open ironwork, 300 m high, with the aerodynamics of their streamlined modern aeroplane. The unexpected association between the two is Gustave Eiffel — ‘le magicién de fer’ — builder of the Tower in 1889, who pioneered much of the experimental research needed by the designers of the first aeroplanes, in the period from 1903, when he was in his ‘70s, until the time of his death aged 90 in 1923.

Post-Second World War generations of aerodynamicists are also probably unaware that Eiffel was the source of many of the basic results they use, since no modern textbooks refer to his researches of 70 years ago; yet nearly half of his obituary notice in the Times of 29 December 1923, headed ‘M. Eiffel — A Great Engineer’ referred to his aeronautical research using his Tower and his wind-tunnels. In order to appreciate how Eiffel came to embark on his new activities at such a late age we must look briefly at his first career, which established him as one of the most distinguished structural engineers of the 19th century, and the political scandal which brought it to an end.

Passive control experiments were made on an 18% thick biconvex aerofoil model in Mach number range giving shock oscillations and at a Reynolds number of 0.7 x 106 with fixed boundary layer transition. The control methods studied included a passive control of shock wave boundary layer interaction by a porous surface and a cavity, and a buffet breather made of holes connecting upper and lower surfaces of the aerofoil. The experiments show that the shock oscillations can be virtually eliminated by these methods. A physical explanation is given for the success of these passive controls.

A method is described for predicting the two-dimensional incompressible turbulent boundary layer on a semi-infinite flat plate under small harmonic progressive oscillations of the free-stream volocity for arbitrary frequency and wave speed. The free stream considered consists of a constant mean on which an oscillating amplitude varying with downstream distance is superimposed. The Reynolds shear stress is modelled by a new single-layer eddy viscosity formulation and.a differential-difference technique is used to solve the governing equations numerically. The oscillatory eddy viscosity formulated is complex, allowing a phase difference between the Reynolds stress and the velocity oscillations. Comparisons between the calculated results and those obtained by other existing methods and measurements show that the method and the turbulence model are satisfactory for a full range of frequencies and wave convection speeds. It is also found that a change in the wave speed has a drastic effect on the boundary layer response.