Navigation has been defined as “the business of conducting a craft as it moves about its ways“. This broad definition of navigation encompasses the whole process of handling, steering, control, guidance and operation of the craft in a safe and economic manner. Navigation has a much longer history than aeronautics. As man first began to explore the world and to develop trade, the need for safe and predictable operation of the craft was a spur to the application of the most advanced science and technology of the day.

This lecture is being given primarily because of the growing tide of concern felt by persons engaged in the class of flying described in the title at what seems to them to be the growing number of prosecutions each year under the Civil Aviation Act 1949 and delegated legislation made under it. During 1966-1967 and 1968 a few low flying cases achieved prominence because the charges were dismissed upon the basis that the prosecution's evidence was inadequate to discharge the burden of proof of low flying. These low flying cases angered not only those directly involved in them but also many persons in the general aviation movement, because it seemed to them unfair that prosecutions should be begun on poor evidence, that large sums of money and a great deal of time and trouble should have to be spent on the defences of them, and that inadequate costs should be recovered from local funds to compensate successful defendants for the costs incurred in their own defences. However, I have chosen to interpret the title as including reference to certain other legal topics outside the criminal.

All forms of transport generate conflicts between the requirements of vehicles and the limits of infra-structures. The struggle, however, is unfair. Vehicles can be developed quickly and users can purchase and put them into service within a short period of time. Infra-structures, on the contrary, can only be modified slowly, not so much for technical as for administrative and financial reasons.

The theme of this symposium is “Inter-Relations and Inter-Face Problems.” It is suggested that what are called “inter-face problems” are sometimes no more than symptoms of a failure to get priorities right. There is, presumably, an “inter-face” between a dog and its kennel. But if the dog owner wants a kennel then he gets one of the right size. The dog takes priority and no inter-face problem arises. Similarly, if someone owns a car and wants a garage for it then he has one built to the appropriate dimensions. It is only if he already has a garage that cannot be enlarged and buys a car too big for it that he is confronted by an inter-face problem but there would have been no problem had he, in this case, given first priority to the garage and bought a car to fit it.

First, let me say what a great honour it is to be asked to take part in one of the Society's symposia, and particularly one on as wide and important a subject as this. Before I start to consider the particular aspects of this subject I must make three points clear.

The first is that, since airports range from primitive landing strips to multi-runway complexes covering ten or more square miles (26 x 106 m2), I should be foolish if I made sweeping statements that might be taken to apply to any one of them. So let me narrow the field to major international airports and dismiss the rest with the generality that transport aircraft today demand airport facilities that are expensive to provide and operate and that if an airport is not supported by a strong and growing demand for air services it is irrelevant and will eventually be put to other uses. I realise that in the USA large airports may handle little international traffic, but my concern is with Europe.

Within the framework of this broad subject, the paper focuses on some of the intra-mural technical and operational planning activities of an airline resulting, directly or indirectly, from airport restrictions of one form or another. While some of the overall problems discussed are, by their complexity, not within the powers of the airline industry on its own to solve, examples are given: (a) of the actions which an airline can take to minimise the effects of a given problem, and (b) of the contributions that an airline can make to solution of that problem. Attention is drawn to conflicts and anomalies in some of the limitations imposed on the airlines by the airports. Several cases in which airport restrictions are beginning to impose new burdens on the aircraft designer are cited.

Current ICAO standards covering the design of airports arise, in many cases, from the problems of flight operations and it would be a waste of time to repeat these. What this paper is intended to do is to discuss, briefly, some aspects which may be new or seen to deserve special emphasis.

In the past aircraft loading has only had a minimal effect on terminal design. In principle the only preference was that aircraft should be parked as near to the terminal building as possible so that load was carried over the shortest possible distance.

There are many who have stated that the arrival of the very large aeroplane is going to cause massive congestion in terminal buildings. This is not really the case, as the very large aircraft themselves will not increase the market. The only effect their introduction has is to bring the traffic into terminals in larger clumps.

I am defining the airport facilities as the strength of its pavements and the sophistication of its passenger and baggage loading and aircraft handling provisions.

To illustrate the effect of pavement strength on design, I have taken two representative sizes of aircraft, 50 000 lb (23 Mg) and 300 000 lb (136 Mg) AUW, and shown in Fig. 1 the effect on undercarriage volume of meeting various values of load classification number (LCN) with appropriate variations of tyre pressure and wheel spacing. The smaller machine has twin wheels while the larger has a four-wheel, twin-tandem bogie. The advantage to the designer of being able to work to a high LCN lies not only in the reduced undercarriage stowage volume, but undercarriage weight itself is saved if the wheels can be closely grouped together.

Three subjects have been selected for discussion in this paper, each of which has a major influence on aircraft design and operating economics. These subjects are airfield performance, noise and aircraft utilisation.

For an aircraft to have good operating economics it must be able to operate with a high load factor over a large percentage of the routes on which it is to be used. The permissible take-off or landing weight, and hence the payload, can be limited by any one of many airworthiness requirements. These include take-off distance and climb, landing distance and climb, and obstacle clearance in the vicinity of the airport.

There are numerous examples in the aero and power producing industries of components which are designed to sustain creep deformation. An important class of structures in this category lies in pressurised shells of revolution. The few analyses which allow predictions of creep deformations to be made are usually restricted to the secondary creep problem, contain approximate relations between stress resultants and deformations or ignore the important effects of bending. While the neglect ot primary creep is not important for cases of steady loading sustained for long periods, stress redistribution should be calculated if the loading period is less than the time taken to reach a stationary state of stress; such a state of affairs is very likely in two-shift operated power producing plant and also in aircraft components. Approximations involving concepts of “sandwich” shells that are often made to form moment-curvature rate relations can be dispensed with by integrating the stress-strain rate relations through the shell thickness. Although the stresses become non-linear through the shell wall they are slowly varying and the integration introduces no problem. The integration requires the use of a digital computer but creep problems have to be solved numerically, except in a very few cases, so that whatever the assumptions automatic computation is necessary. While some practical shells approximate to the momentless condition the most likely case will include bending which, although likely to be relaxed by a process of stress redistribution, will cause additional creep straining.

The Black Brant IV shown in Fig. 1, is a two-stage sounding rocket with a 15KS-25 000 booster motor stabilised with three fins and a 9KS-11 000 motor, a 5·3 fineness ratio conical noise and an 11·5° conical flare forming the second stage. Basically, the second stage is the single stage Black Brant III rocket, but uses a conical flare instead of three fins at the aft end for aerodynamic stability. This paper reviews the static stability of a Black Brant IV second stage with a flare and two fin-flare combinations.

When a rotating body is placed in a stream of fluid the viscous drag of the rotating surface moving forward on one side and backwards on the other causes the flow velocity to be lower and hence the pressure on the forward-moving side higher than on the backward-moving side, thus giving a lateral (lift) force L in the direction shown in Fig. 1. This force, known as the Magnus force, is well known to engineers and also to sportsmen. In tennis, for example, top spin is used to swerve a fast ball downwards so that it falls within the required area of play, while in golf the Magnus force causes the all too familiar sliced shot when the club is drawn across the ball at impact.