The Men who could best lay claim to the title of “Aeronautical Engineer” were the early pioneers like Wilbur and Orville Wright. They were their own research workers, their own designers, their own draughtsmen, their own constructors, their own test pilots and, later on, their own salesmen. The Wright brothers carved and steamed the bamboo ribs and struts of their aeroplane themselves, brazed and spliced the wires and cables, while their sister Kathleen stitched the flimsy fabric. But the day of the craftsman-designer is gone.

This paper is concerned with the present-day professional aeronautical engineer in industry and in particular, with the aircraft designer. A distinction must be drawn between the aeronautical engineer and the aircraft technician; both may be intimately concerned with the design of an aeroplane, but the technician—the stressman, the aerodynamicist, the draughtsman—is at the most an embryo aeronautical engineer.

The energy that is suddenly released when a structure fails under load usually presents one of the minor problems in strength testing technique. Care has to be taken to ensure that the strain energy in the structure does not do further damage after primary failure and so obscure the location of the original weakness; and the possibility of risks to personnel must not be overlooked. As a general rule, however, aircraft structures fail in strength tests without untoward effects. Most of the strain energy within the structure is absorbed internally or dissipated in loading gear and anchorages, and the most noticeable effect is the noise and vibration which is produced.

An opinion exists, more felt than written or spoken, that safety standards in air transport do not keep pace with technical progress. The facts belie this and, given a united effort by all concerned, there should be opening up a period of increased safety.

A simple comparison of the characteristics of say, the Ensign class with more modern aircraft, cannot reveal progress, and might even show the reverse. Commercial competition, operational demands, and public expectations have taken us beyond the stage when we can think in terms of the aeroplane alone and have led to the present state when air safety can only be examined in terms of the aircraft associated with ground equipment and airline organisation.

The main function of refuelling in flight is to increase the range, or increase the payload over long stage lengths.

The quest for range has brought about a steady increase in aircraft size throughout the years and it has now become apparent that a new barrier, the range barrier, is an even more formidable barrier for designers to overcome than that caused by increasing resistance with increasing speed, especially at the speed of sound.

Figure 1 shows the weight of record-holding aircraft plotted against distance, from the first flight, of 284 yards, by Orville Wright in 1903. By 1909 Bleriot heroically struggled across the English Channel, a distance of 22 miles, and this was followed in later years by the Atlantic conquest by Alcock and Brown in 1919, Lindbergh's solo Atlantic crossing of 1927, and so on to the more recent record achievements of the B29 “Pacusan Dreamboat” and the P2V-1 Neptune “Truculent Turtle.”

The pure bending of a rectangular beam about an axis parallel to a principal axis of its cross-section is well understood if its depth d is comparable in magnitude with its breadth b. The usual theory, noticing the geometrical fact that at any cross-section the longitudinal strains of filaments of the beam are proportional to the distances of the filaments from some neutral axis parallel to the axis of bending, postulates that the longitudinal stresses will vary in the same way.

Many engineers probably regard riveted joints as a very elementary feature of construction, worthy only of a passing reference in a first year Engineering Course, or a page or so in the appropriate “Handbook”.

In fact, modern aircraft riveting is an extremely complex subject.

This paper is concerned with a suggested technique whereby light alloys, already possessing high mechanical properties due to heat-treatment, may have these properties further enhanced by the judicious use of cold-work. It is proposed that in the search for methods of reducing the weight of important aircraft components, the question of mechanical properties in general, and ductility in particular, should be reconsidered from an unorthodox angle.

The role of meteorology in air operations is becoming increasingly important and an understanding of meteorology is desirable in the consideration of a number of the problems to be faced. The forecasting of winds en route and the use of these forecasts is one such problem, which has been brought into greater prominence by the advent of fast, high-flying aircraft. A great deal of work is being done on upper air winds and it is already clear that curious and significant phenomena sometimes occur. Thus very high winds are sometimes found in belts of limited lateral extent—the so-called “jet stream.” Not only high winds, but high rates of change of wind occur in such regions and they are clearly a potential source of difficulty to the navigator. Apart from the jet stream —a meteorological highlight of recent development—airline operators are also concerned with the problem of route planning.

Measurements were made in the Royal Aircraft Establishment High Speed Tunnel of the drag of a wing with various grades of surface roughness in the form of camouflage paint. The measurements were made for a range, of Reynolds number from about 4.5 × 106 to about 15 × 106 at a constant Mach number of 0.2, and for a range of Mach numbers from 0.2 to about 0.7 at a constant Reynolds number of 4.5 × 106 and to about 0.6 at a constant Reynolds number of 6.0 × 106. It was found that for the range of Mach numbers tested compressibility had no appreciable effect on the drag increase due to roughness (Figs. 2 and 3). Further, the drag effect of each roughness tested was such that an equivalent size of sand roughness Ke, of the type tested by Nikuradse, could be readily associated with it. For each finish tested a number of roughness records were taken by means of a roughness gauge developed by Dr. Tomlinson, of the National Physical Laboratory (Fig. 5).

In presenting this paper on the producing of a prototype aircraft it is not the author's intention to deal with the overall conception of the type or such matters as operational requirements, performance, type of construction and so on, but rather to start from the point where the general arrangement of the aircraft has been drawn and to try to describe what, in his opinion, should be the best way to produce the aircraft in the shortest possible time and at the least possible cost.

In the past, the majority of civil aircraft have been powered by engines which have been developed primarily for the Royal Air Force. Their development costs have been borne by the Service departments, and then they have been converted for civil use at comparatively small extra cost.

It has always been questionable whether these converted engines have been really suited to their civil role, and it will become even more doubtful the farther the design and performance of civil aircraft depart from those of military aircraft.

In this paper, an attempt has been made to coyer the more important requirements for the two kinds of engines, and to see how they compare. If it appears that too little has been said concerning the gas turbine, that is because there is as yet no experience of its commercial operation.

The opinions expressed in the paper are the author’s and have no official significance.

It is a curious reflection on the progress of science in our time, that a term which has only come into common use in aeronautics in the last decade commemorates the name of a man who carried out his researches some fifteen years before the Wright Brothers first flew in 1903. The obscurity surrounding Ernst Mach, whose name is given to the ratio of the speed of flow of a gas to the speed of sound under the same conditions, is ill-deserved, for there can be little doubt that he was one of the outstanding scientific personalities of the nineteeth century; this distinction arises not so much from his experimental work, which was extremely valuable, but more from his original conceptions on the philosophy of science which helped to lay the foundation for modern developments in physics.

It was desired to confirm quantitatively pilots’ impressions that on turbine-jet aircraft in the region of 40,000 ft. the level speed stabilised very slowly.

The time required to make a conventional level speed measurement has been examined, for a representative turbine-jet aircraft, over a wide range of air speed and height. The results are compared with those for a typical piston-engined aircraft and their implications discussed.

It is concluded that the time required to make a conventional level speed measurement increases rapidly with height, in the absence of compressibility effects on drag, and is about five times as great at 40,000 ft. as at sea level. It is inconveniently large at high altitude and level speed measurements there will require very long runs, unless it is arranged that each run is started at an air speed near the steady level speed.

This increase will be present in most level speed tests, especially those in the region of the best speed for range. In maximum level speed measurements, however, compressibility effects may be present and the air speed may then be expected to settle down quickly.

The need for long runs at high altitude is not peculiar to jet aircraft, but has come into prominence concurrently with them.

The subject of statistics is so vast that many thousands of volumes have been written on it and it would be lunacy to try to give any complete outline in a brief paper. Even by confining the field to that range of data arising from aeronautical engineering the limit seems to recede into specialist abstractions rather than narrow as generality is jettisoned. At the outset it may be well to consider these apparent platitudes because many (most?) otherwise well-informed people are dogmatic in their belief that statistics are merely applied arithmetic. No doubt the same kind of thing was said before any distinction was drawn between a tally-clerk and a qualified accountant. The assertion contains too much fundamental truth for easy rebuttal: nevertheless there does exist both a science and an art in statistics, and arithmetic is only one important contribution to the exercise of either.

It is odd to think that the resistance-wire strain gauge could have been put to use some 40 years ago, about the time of the first filament-wire lamp and the thermionic valve. The physical principles involved were already known. Kelvin had measured the resistance of wires in tension, there were galvanometers in plenty, and even crude valve amplifiers existed. It only really remained for someone to put two and two together. Instead we had to wait until the necessity of stressed-skin construction forced the hand of the engineer into seeking a more effective method of strain analysis than the old empirical ways.

Designers and technicians pay a great deal of attention to the development of jointing methods for use in the construction of aircraft. A satisfactory method should be neat, economical in labour, flexible in application, and capable of yielding consistent results with a low weight penalty.

Electrical resistance welding meets the above requirements and it is with this process that I shall deal.

In systems for transmitting control motion there may be two shafts set in any relative position, each carrying a lever arm, and the ends of the lever arms may be connected by a link having ball ends. In general, the range of working movement for such a system is somewhat limited and the relationship between the angular movements of the two shafts is non-linear.

Although for some purposes it may suffice to mock-up the system and determine the motion experimentally, for other purposes analytical treatment may be required. The general solution given below is readily applied to particular cases, which may be simpler.