The Eighth British Commonwealth and Empire Lecture was given by Mr. R. E. Hardingham, O.B.E., F.R.Ae.S., M.S.L.A.E., before the Royal Aeronautical Society on 2nd October 1952 at the Institution of Mechanical Engineers, Storeys Gate, S.W.I. The audience included a number of distinguished guests, among them visitors from overseas and representatives of the Divisions of the Society.

Mr. G. H. Dowty, F.R.Ae.S., President of the Society, at whose suggestion the British Commonwealth and Empire Lectures were started in 1945, presided over the meeting. After welcoming the guests Mr. Dowty introduced Mr. Hardingham, outlining his career briefly. Mr. Hardingham was one of the original apprentices at the Royal Aircraft Establishment and in 1921 joined the de Havilland Aircraft Co. Ltd. Later he served for three years with the Air Ministry during which period he was associated with the Aeronautical Inspection Directorate and the Directorate of Technical Development. He joined the Air Registration Board on its formation in 1937, becoming Principal Surveyor in 1945. In 1947 he was appointed Secretary and Chief Executive and that same year became an Officer of the Order of the British Empire. Mr. Hardingham has represented the United Kingdom at a number of International Conferences.

In the past attempts have been made to correlate the estimated load variations which the component will experience during a stipulated lifetime (in hours) with estimations of the fatigue strength (in cycles of loading) for typical structural components, such as wing spar boom joints, riveted joints, and so on. The trend of thinking so far has been that one should design for a certain fatigue life. In this paper it is shown that, even with the most careful attention given to the detail design of aluminium alloy components, it is not possible to attain what has been regarded hitherto as the minimum acceptable fatigue strength for typical structures, i.e. 2 x 106 cycles of 1g±7½ per cent. ultimate strength of the structure, based on present British Civil Airworthiness Requirements (Reserve Factor 1.0). There is no implied criticism of the criterion which is an ideal one, and if structures attained the criterion then the fatigue life would be adequate.

The thought that the highlights of history four centuries ago will repeat themselves in our time is growing, but the word and the wish are not enough. It will need to enter the heart and soul of the people and the nation, if another prolonged period of prosperity, highlighted by the deeds of the adventurous, is to be ushered in.