Quite by chance after this lecture had been written I saw at first hand part of the fire-fighting operation in the Tanneron in the South of France using flying-boats. This provided an excellent point from which to begin.

On 23rd August 1986 a vast fire was started deliberately, it was alleged, in the valley of the River Siagne, between Grasse and Mandelieu. There was a strong mistral blowing at the time. It was brought under control two days later with the aid of a small force of around nine ‘Pelicans’: Canadair CL-215 flying-boats (Plate 1). Each aeroplane can scoop up over 5000 litres (more than five tons) of water, in 10 seconds while planing at 70 knots (Plate 2). At times three aircraft would land in loose formation to do so. In the end the fire, said to be the worst since 1706, was reported to have destroyed 10 000 hectares (say 25 000 acres) of farm, forest and homes. Four people died, 700 suffered from burns and asphyxia, 8000 were left homeless.

Experiments were conducted to study shock-induced separated flows on the lee surface of delta wings with sharp leading edge at supersonic speeds. Two sets of delta wings of different thickness (10° and 25° normal angle), each with leading edge sweep angles varying from 45° to 70°, were tested. The measurements, carried out in a Mach number range from 1.4 to 3.0, included oil flow visualisations (on both sets of wings) and static pressure distributions (on the thicker wings only). Using the test results, some features of shock-induced separated flows, including in particular the boundary between this type of flow and fully attached flow, have been determined. The experimental results indicate that this boundary does not seem to show any significant dependence on wing thickness within the limit of thicknesses tested. It is shown that this boundary can be predicted for thin delta wings using a well known criterion for incipient separation in a glancing shock wave boundary layer interaction, namely that a pressure rise of 1.5 is required across the shock. Comparison of the predicted boundary with experimental results (from oil flow visualisations) shows good agreement.

A velocimeter is described based upon the same principle as the five-hole Conrad tube yawmeter. However it uses a single tube, cut obliquely at 45°, that rotates about its own axis together with an outer closely-fitting concentric tube, cut normal to its axis, that can be slid forward over the mouth of the chamfered tube. The small measuring volume, about 1 mm3, and well-defined measuring point enable the probe to be used with some confidence in regions of high shear. Some typical results obtained with the probe in a highly-sheared, three-dimensional flow are given.