I would like to express my thanks to the Council of the Royal Aeronautical Society for inviting me to deliver this lecture. I am very happy that this honour has been extended to me: I am happy for myself, and also for my country, Barbados, one of the newest sovereign states, but one which has evolved with the British Commonwealth. Our relationship has existed since 1625 and apart from what I believe to be the first case of UDI in the British Colonial Empire in the Cromwell era, we have been stalwart members of the club.

In November 1966 Barbados became a sovereign state, the colonial days were over. From here on we have been a full member of the British Commonwealth of Nations.

In their time few writings on the .subject of aviation can have been as avidly read, as furiously debated and as lovingly quoted, as have those signed “C.G.G.” The initials stand for Charles Grey Grey. Spelt with an “E”. Both times. My recollections are of a man with no special gifts in the way of scientific ability or technical achievement 'who, in the most advanced industry of his day, grew to a stature when he became a figure of much concern to industrialists and civil servants alike. He walked and flew with dictators but, though very much a man of the right, never lost the common touch. Somebody, I think it was the late Roland Dangerfield, called him a “democratic old aristocrat”.

Sir William Hildred drew upon his personal experiences until 1966 as Director General of the International Air Transport Association.

That body worked closely with the International Civil Aviation Organisation (ICAO)—the author, instigator, and watchdog of Annex 9 of the Chicago Convention which dealt wholly with the subject of facilitation. Neither body had legislative power. ICAO could only make recommendations but these required the assent and action of Sovereign Governments before they became effective. The President of ICAO had said it was the increase in passenger and cargo volume which created the problem but Sir William ascribed a good deal of it to the entrenched conservatism of Governments and their operating agencies.

Annex 9 to the Convention on International Civil Aviation is entitled “Facilitation” and in the foreword to the fifth edition there is what might be termed a definition of facilitation … “all practical measures, through the issuance of special regulations or otherwise, to facilitate or expedite navigation by aircraft between the territories of Contracting States, and to prevent unnecessary delays to aircraft, crews, passengers and cargo, especially in the administration of the laws relating to immigration, quarantine, customs and clearance”. I am here to give a shipper's view of facilitation and therefore, am concerned only with cargo. I hope my views are not coloured by experiences I have had as crew or passenger which tend to be much more personal and immediate.

I had intended to speak about passenger control, and cargo control is not really my subject. Nevertheless, in view of what has been said by previous speakers, there are one or two points on cargo matters which perhaps I might make at this stage. I should first of all say how admirably I think Mr. Leeper dealt with a number of the points raised by Sir Archibald Hope. I do not think he could have put the general Customs point of view in a better way. I was not always sure whether the speakers were referring to their experiences with the UK Customs or with other countries’ administrations and I think several of them did admit that their criticisms were not levelled against the home customs.

Immigration control is an expression of national interest. The objective is to ensure that, of all those people who wish to come from abroad to work and settle here, we should accept only those whom it is in the national interest to accept. The process of selection must be operated in a way which does not delay or inconvenience the great generality of travellers.

In more detail, the current objectives of the UK immigration control are: —

1. (a) to prevent the entry of people who are personally unacceptable, for example, because of criminal record;

2. (b) to protect and supplement the resident labour force;

3. (c) to prevent immigration of a type, and on a scale, which might give rise to serious social problems.

The organisations involved in health facilitation are 3 international ones, 1 national one and 1 local one.

The three international ones are:

(a) The World Health Organisation, an offshoot of the United Nations and before that the League of Nations. This body has headquarters at Geneva and disseminates on a daily basis, world-wide information on epidemic diseases, thus keeping countries fully informed of the current disease position in other countries.

(b) The International Civil Aviation Organisation, which is a consortium of Government Agencies which draws up statutory regulations for the international control of air travel including, among others, personnel and medical problems. Its objective is to implement the Chicago Convention which, in turn, was the successor to the Paris Convention. It is obviously desirable that recommended practices of medical standards for pilots should be uniform throughout the world. Sir Frederick Tymms was at one time the UK representative.

(c) The International Air Transport Association, a voluntary organisation of air operators which endeavours to regulate conditions among commercially competing airlines. The medical committee, like other committees, makes an annual report to the Executive. Sir Wjlliam Hildred was its distinguished chairman for many years.

The lecture I am going to give attempts to cover, in forty-five minutes a subject that really merits a series of lectures. This, of course, displays a fitting disregard for minor difficulties, of which, I am sure, the dauntless spirit of Sir George Cayley would have approved.

The broad title permits consideration of all methods of intelligence gathering from the air, including the more widely known optical photographic systems, and has been deliberately selected for this purpose. To avoid clumsy and longwinded definitions I will frequently have recourse to the the use of “in” terms such as Sensor, Multi-Sensor, Exploitation, Environment and many others.

I Feel highly honoured at having been asked to deliver this inaugural lecture as a prelude to the bi-annual series of Memorial Lectures on the development of Civil Aviation in South Africa. This lecture will be devoted to the man—Major Allister Macintosh Miller.

Much has come about in the field of Civil Aviation since the days I am going to speak about. Space and time have been telescoped. Colossal strides have been made. In this hall tonight I see a number of persons who, like myself, are able to make the comparison between the civil aircraft of vintage 1919 and the civil aircraft of today.

Determination of the cross-sectional dimensions of panels of least weight typically follows the procedure set out by D. J. Farrar in this JOURNAL 20 years ago. Farrar made the assumption that for panels of least weight the flexural and local instability stresses were coincident. Using this he investigated the Z-section stringer-skin combination and later, using the same method, E. J. Catchpole studied the panel having unflanged integral stiffeners. In both cases the panel is treated as a wide strut, i.e. the flexural buckling load was taken to be the Euler buckling load, no account being taken of the effect of edge restraint.

It is a well-known fact that buckling values for columns under dynamical loads are different from those under static loads. Meier, Gerard and Davidson have already investigated the dynamics of the buckling of elastic columns theoretically and experimentally, and Hoff discussed analytical methods in detail. However, solid viscosities are neglected in all these researches. Previously, the author obtained the relationships between dynamic load factors and solid viscosities, and it was found that their effects on dynamic load factors cannot be neglected. It will be interesting to investigate the relationships between solid viscosities and dynamic buckling values.

The rectilinear flow of an incompressible viscous fluid along a duct of uniform cross section due to an oscillating pressure gradient has been considered by a number of investigators. The duct of circular cross .section has been treated by Richardson and Tyler and Sexl, the elliptic case by Khamrui, and the rectangular case by Drake and Fan and Chao. Recently Jeng has discussed the importance of this type of flow and has given a procedure for calculating a numerical solution for a duct of arbitrary cross-section. An interesting feature of these flows is that, at large frequencies when the flow is of boundary-layer type, the velocity at any instant has its maximum near the walls, the velocity overshooting its almost uniform distribution at the centre of the duct.