In pondering on a subject for this, the fifteenth, memorial lecture, I hoped to find something that might reflect the spirit of Frederick William Lanchester's work. But first of all, I tried to learn a little more of the man himself: his history and the design of events that agitated his enquiring mind. Most of what I discovered only emphasised my own unworthiness to contribute to his memory. For I am a member of Imperial College, and it was from that Institution that Lanchester left, disenchanted, in his third year without taking his degree. Worse still, I hold the Zaharoff Chair of Aviation; in one of my distinguished predecessors, Lanchester was later to discover a fierce opponent to his theory of the lifting wing and to his equally remarkable vortex theory of the propeller. It was only in another sphere, that of the Aeronautical Research Council, that I was able to establish a happy bond between us.

Hot wire anemometers have found widespread use in the measurement of turbulence for many years. Recently, considerable improvements in the signal to noise ratio of these instruments has facilitated measurements in the high wavenumber region of the energy spectrum, where the turbulent energy level is usually relatively low.

Of major concern in the measurement of very small scale turbulent fluctuations by the hot wire method is the error introduced by the spatial averaging effect of the wire. Clearly, for fluctuations with wavelengths of the same order of magnitude as the wire length, or less, the line integration of the wire results in measured amplitudes which deviate considerably from those which would be recorded by a probe of infinitely small size.

To ensure successful operation of aircraft at high angles of attack (or high lift) conditions, attention must be paid to two basic design aims. These are the ability to achieve an adequate high lift performance and the need to ascertain that inadvertent penetration of the post-stall regime (or more generally any critical condition, which may for a particular aircraft be considered as replacing the conventional stall) does not lead to uncontrollable and thus potentially dangerous flight conditions.

The first aim is concerned primarily with the maintenance of the flow pattern associated with the normal flight regime and the augmentation of the lifting capability of the wings to sufficiently high lift coefficients. It, therefore, relates to the design of the wings, leading-edge devices and the flap system, if any, in respect of the onset of the flow breakdown.

In recent years much attention has been given to developing new methods of steering tactical missiles. One method of particular importance is known as thrust vector control (TVC) which allows the missile to be steered by vectoring the efflux from the propulsion engine. In the case of engines powered by liquid fuel the normal TVC technique is to swivel the complete combustion chamber. This method is, however, unsuitable for solid propellant motors and so different techniques have been developed. This present paper makes a comparison of different systems of recent origin developed within the UK which are now available for project application.

The economic advantages of the Woomera Launch Site in South Australia that were all important in the initial formation of ELDO were, by 1966, outweighed by the limitations that the north pointing range imposed on future applications of the three stage Europa Launcher. The predominance of equatorial orbits (and, in particular, geostationary orbits) in the communications satellite field, demanded a near equatorial, east pointing range for efficient satellite launching.

To overcome this limitation on future Europa applications, a supplementary programme to establish an equatorial launch site (ELS) at Kourou in French Guyane, and to develop the Europa 2 launch vehicle for operations from the ELS, was therefore initiated in 1966.