One big problem found during the course of preparing this lecture, was the vastness of the subject. So there will probably be many things that should be said that will be left unsaid, but it is hoped that all the main factors have been considered at some point, even if they only get a passing mention. One point should be made, the freight and cargo market are not considered, as the majority of freight is carried in converted passenger aircraft or in the holds of passenger aircraft particularly in the large wide-body types. This trend seems likely to continue and it is unlikely that specialised freight aircraft will be developed for short haul operations.

If one sees a satellite as being a remote sensing platform or as a communication path between two terminals on the Earth, one can appreciate that the spacecraft and its complementary ground infrastructure are essentially electronic devices handling data for the benefit of a ground-based investigator or user. As such, there is a space data-handling system which comprises an onboard and a ground segment. Both segments cover the functions of data collection, data distribution, data processing and storage, data encoding and decoding, timing and synchronisation of events, and data transmission and reception currently forming the well known telemetry data link and the telecommand data link (TTC).

Even with today’s computers, a wind tunnel is an essential tool in engineering, both for model tests and basic research. Since the 1930s, when the strong effect of free-stream turbulence on shear layers became apparent, emphasis has been laid on wind tunnels with low levels of turbulence and unsteadiness. Consequently most high performance wind tunnels were designed as closed-circuit types (Fig. 1(a)) to ensure a controlled return flow. However, as will be seen below, it is possible with care to achieve high performance from an open-circuit tunnel, thus saving space and construction cost. ‘Blower’ tunnels (with the fan at entry to the tunnel, Fig. 1(b)) facilitate large changes in working section arrangements; to cope with the resulting large changes in operating conditions, a centrifugal fan is preferable to an axial one. For ease of changing working sections the exit diffuser is often omitted from small blower tunnels, at the cost of a power factor greater than unity. This paper concentrates on the design of small blower tunnels but most of the information is applicable to wind tunnels in general.