In recent years, there have been rapid advances in the development of theoretical methods in aerodynamics, particularly for transonic flow calculations. Many papers have been written on this topic. It is however appropriate that there should now be a paper that concentrates not so much on the methods themselves but on the use of the methods for computer-aided design. One could say that the most striking development in the UK in the past two-three years has been that the methods are no longer merely within the preserve of the research establishments; they are being actively used by the aircraft industry in the design of actual aircraft projects. Any air of scepticism about their value has been dispelled. The designers are now appreciating through their own experience that with the aid of a powerful computer and indeed in some cases, a computer of only modest capacity, they can specify a shape for the first wind tunnel model of a new project with much more confidence that the test results will show that the shape is near what is required to achieve their design objectives. It is already being claimed that in this way, the time-scale of the design cycle is being shortened considerably. Also, the computer and the theoretical methods are being used increasingly in the interpretation of the test data. The forecasting of the full-scale characteristics on the basis of the model test data is developing into more of a science and less of an art based on past experience.

The MADGE aircraft approach aid is being supplied to Mobil for fitment to the Beryl ‘A’ Platform in the North Sea where multiple approach paths, offset in both azimuth and elevation are to be provided. Application has been made to the UK Civil Aviation Authority for approach limits of 150 ft (200 ft for Beryl ‘A’) Minimum Descent Altitude and 300 metres RVR equivalent.

MADGE was originally designed to meet a NATO requirement for a tactical approach aid which could be carried by two men, and set up in 15 minutes and give guidance to all aircraft types. This is a totally different application from the one at Beryl ‘A’ and yet it uses the standard MADGE production airborne equipment and standard MADGE production ground station units supplemented by ancillary ground equipment to provide offset tracks and monitoring facilities.

The discovery of oil in the North Sea has resulted in a rapid expansion of helicopter operations in the United Kingdom.

The pilots currently flying to and from oil rigs have either VFR ratings only or hold Certificates of Instrument Flying Competence. With the congestion of traffic in the North Sea area, there is clearly a requirement for increasing safety without further increases to traffic from training flights.

According to Flight (2nd September 1978), legislation is to be introduced to establish an Instrument Rating (Helicopters) with effect from April 1979. Many of the pilots now flying will need further training to achieve this rating.

British Airways Helicopters have installed a simulator for the Sikorsky S61N helicopter at Dyce airport, Aberdeen to facilitate training of pilots to fly the aircraft most commonly used for oil rig work. The simulator will be used for many aspects of training including instrument training.

What do we mean by reliability? Mathematically, it is the probability that a piece of equipment will be capable of working when called upon to do so for the time required and under the environment specified, and, if we know the mean time between failures and make certain assumptions about the randomness of the failures, we can derive expressions that will give numerical values of inherent reliability.

In layman's terms, we can say that it is the ability of a piece of equipment, whether it be a small component or a complete aircraft, to be ready to work and to continue to work in the environment for which it has been designed, for as long as the specification requires it to do so and to do this with the minimum amount of maintenance.

When British Aerospace, Brough, were first tasked with carrying out a study of mechanical systems and component reliability it was anticipated that the installed environment would be a significant parameter in the investigation. Consequently it was decided to carry out a separate study of the environment of equipment on a number of aircraft to assess how this had influenced the design and subsequent reliability of the components and to see if the initial assumptions had been valid. This study was to make use of measured data from routine development flying as well as tropical and cold weather trials. In addition the reliability of appropriate equipment was reviewed to determine the incidence of problems arising from environmental factors.

The installed environment can be broken down badly into two separate factors. Firstly, those which are external to the components in question, e.g. altitude, ambient temperature, humidity, vibration levels, solar radiation and contaminants such as salt, sand and dust. Secondly, there are those factors which are internal to the component in question or are influenced by the installation of the component in a larger system. These factors include internal pressures, temperatures and contaminants, the effect of the system flows and interaction with other components.

The local buckling behaviour of structural sections composed of isotropic flat plate elements is well documented. The results are most conveniently presented in the form of curves for the minimum buckling coefficient, Kmin, against the flange/web ratio λ2. A series of such curves for a range of structural sections composed of orthotropic plates subjected to uniform end loads and simply supported end constraints has been presented by the author. For isotropic sections of practical proportions, it is generally assumed that the buckling coefficients for columns with simply supported and built-in end conditions approach the common value Kmin, and that the half wavelength of the buckle mode in the axial direction is of the same order as the cross-sectional dimensions of the column. For structures composed of highly orthotropic materials such as carbon fibre reinforced plastic (CFRP), the half wavelength is much greater than that of the isotropic counterpart. In consequence, it is only for much longer sections that the common value of Kmin, can be assumed for the buckling coefficient of built-in orthotropic sections without excessive error.