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FOR a number of years now it has been evident that a successor to the well‐tried Vickers Viscount and Convoir 240/340/440 series was required. However, the big problem was to design an aircraft such that its economics and passengerappealweresub‐stantially better than the machines it would ultimately replace. Other important factors which had to be con‐sidered were improved reliability, easier and cheaper maintenance, higher standards of safety and means of reducing ramp times. Furthermore, the difficult choice of passenger capacity and cruising speed had to be made. Probably the easiest decision was to employ the twin‐engine configuration with the power plants placed in the now familiar rear position, one on cither side of the fuselage.

ACCORDING to historical records the earliest known drawings for an aerial machine that can be classified under the heading of helicopter were made in the fifteenth century by the world renowned Italian scientist and artist Leonardo da Vinci (1452–1519). Probably the Chinese had been making their helicopter toy for some considerable time before da Vinci commenced his experiments. This toy consisted of two feathers, joined together by means of a cork or soft wood boss, to form a crude type of propeller which was pushed up a threaded stick so that upon leaving the stick the propeller rotated at high speed and continued to screw itself up in the air. When the speed of rotation decreased the propeller slowly windmilled down to the ground. A similar toy is still being sold today.

The Canadair Challenger is a high‐speed, long range airplane designed for the business jet market of the 1980s and 1990s; it is an all new aircraft that incorporates advanced airfoil technology, high by‐pass ratio fan engines, advanced materials, advanced systems and a wide body fuselage to provide interior cabin space consistent with the long range capability.

Details of the Hydraulic, Engine Control, Electrical, Fire Protection, Flight Control, Air Conditioning and Cabin Pressurization, Ice and Rain Protection, Radio and Auxiliary Power Plant Systems. IN order that high utilization rates and low maintenance costs may be achieved it was necessary to match the fail‐safe, long‐life structure of the HS.748 to trouble‐free systems. The system design philosophy adopted on the Hawker Siddeley 748 was ‘avoid complication and use proven components wherever possible’. This approach together with a layout whereby external access is provided to all systems has produced easy and almost trouble‐free maintenance. The majority of the system components are installed under the cabin floor and are grouped as shown in Fig. 1. Access is through the landing gear doors or four large quick release elliptical access panels enabling all trades to work on the aircraft at the same time.

Today's high speed aircraft must have external surfaces as smooth as possible, and in order to reduce drag to a minimum it is usual to employ flush riveting for all external skin sheeting. Whilst this method of construction provides a basis for a smooth surface it is not in itself fully satisfactory, especially on a curved surface where there is no certainty that all the rivet heads lie flush with the surrounding skin sheeting. It is possible to attain a finish nearer to that desired by using an end milling tool on the rivet heads, but there is still a danger when using normal tools of this type that the surface of the sheeting will be damaged. Thus it has become necessary to provide a tool with which the likelihood of such damage is greatly reduced. The Short Rivet Milling Tool has been designed by Short Brothers and Harland Limited to overcome this problem. It can be used in conjunction with a portable power driven unit, e.g. a compressed air operated hand drill, and comprises a circumferential milling cutter, a cutter spindle, a housing containing bearings for supporting the spindle at right angles to the driving axis and an attachment to the power unit. Two guide rollers, one each side of the cutter, project very slightly and thus prevent the cutter from touching sheeting surrounding the rivet under treatment. Although these guides extend only 0.0005 in. this is sufficient to ensure that the cutter operates only on the rivet head. Varying widths of milling cutters may be fitted to the tool by withdrawing the cutter spindle and inserting spacing bushes of appropriate width. In operation the tool can be used for ‘rubbing down’ protuberances, in the same manner as a smoothing plane, with the drill shaft axis at an angle of about 60 deg. to the surface being worked upon. Exhaust air from the tool is collected internally and used for the dispersal of swarf.

Introduction Cathodic protection is used to prevent corrosion of buried or immersed steel structures. Current is made to enter the surface of the structure via a system of anodes, and the structure is the cathode, hence the name cathodic protection.

Looks at recent developments in methods of decentralising an aircraft’s hydraulic system made possible by the production of miniaturised electro‐hydraulic pumps with their own “smart” actuators.

THE coining of the phrase “work study” implies that someone wanted, without a noisy grinding of axes, to give time and motion study, as practised, a boost. So “work study” was born, all the old techniques were dressed up in a “new look,” and the whole show was presented to industry as “different”—it was a box‐office hit.

WITH a low noise level of less than 59dBa at one metre, the 400Hz ground power systems from MPL Power Systems plc are said to be ideal for operation in noise conscious environments such as airports. For use as decentralised or centralised units they accommodate a wide range of aircraft types and claim several advantages over conventional mobile units. Developed from the MPL TQ range of 400Hz silenced frequency converters which are used in well over 30% of large data processing mainframe sites throughout the UK, they offer an output noise which is so low that, if necessary, units can even be unobtrusively installed in passenger areas.