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THE period from 1884 to 1937 (the events of which are summarized on earlier pages of the pamphlet) may be said to have been exploratory as regards aeronautical science in Australia. Many beginnings had been made in research, in teaching and in manufacture, but, no generally organized growth had occurred. The visible beginnings of the present developed state of the industry and of research may be traced from two sources.

IN order to study the relationship of load factors to the stresses which arise in the normal manoeuvring of aircraft, it is customary to employ recording accelerometers. These instruments have been found quite satisfactory for this purpose, and almost as many models have been devised as the countries that use them. The instruments built in this country have been the very best of the type: the record is usually, though not invariably, made on a moving photographic film. For certain purposes, however, a simpler form suffices; one in which an easily‐visible pointer moving in front of an easily‐visible scale gives the maximum acceleration during any sustained manoeuvre, such as turning, rolling, looping, pulling out of a steep dive, etc. The inertia of the mechanical parts, though, of course, exceeding that of the mirror and spring of the usual recording type, can be made low enough to keep pace with the ordinary motions of an ordinary aircraft. Such a device needs to be light in weight, slight in bulk, and simple to use and maintain.

IN introducing him to his audience when he read to the members of the Royal Aeronautical Society his lecture on control‐surface and wing stability problems, reproduced in this issue, the President of the Society, MR. H. E. Wimperis, said that MR. PUGSLEY was not so well known to the members as he ought to be. In this respect then, regular readers of AIRCRAFT ENGINEERING may be said to be the more fortunate, for it is now five years since we introduced him to them by publishing, in September, 1932, an article written by him on “ Torsional Instability of Struts.” Since then his name has become familiar to those who study the Aeronautical Research Committee's Reports and Memoranda, all of which are abstracted in AIRCRAFT ENGINEERING, to which series he has made a number of contributions.

IT is twenty years ago almost to the clay since the world was saddened by the news of the death of one of its heroes—Wilbur Wright. The inspiring story of the successful attack made by the two brothers, Wilbur and Orville, on the age‐long problem of human flight is too well known to be told at length here. But it is remarkable that the first flight by a motor‐driven aircraft on December 17th, 1903, was made only two years after Chanute, in a speech before the Western Society of Engineers, had felt compelled to use such cautious words as these: “There is some hope that, for some limited purposes at least, man will eventually be able to fly through the air.” Chanute made that speech when introducing a lecturer none other than Wilbur Wright himself. One wonders what the lecturer thought. What he said is on record and I quote a passage which tells us what it was that turned his and his brother's attention to the problem of flight: “My own active interest in aeronautical problems dates back to the death of Lilienthal in 1896. The brief notice of his death which appeared in the telegraphic news at that time aroused a passive interest which had existed from my childhood, and led me to take down from the shelves of our home library a book on ‘Animal Mechanism,’ by Professor Marey, which I had already read several times. From this I was led to read more modern works, and, as my brother soon became equally interested with myself, we soon passed from the reading to the thinking, and finally to the working stage.”

THE application of scientific principles to the design of aircraft and aircraft equipment during the post‐war years has yielded results which are becoming increasingly apparent. The time interval which elapses between the conception of an idea and its application to production aircraft is necessarily long, but it would seem that we are just beginning to reap the reward of much patient study.

THE use of a rotating wing in place of a fixed one has long had a peculiar fascination for inventors, no doubt due in the main to the attractiveness of hovering flight, as it is called. The ability to hover carries with it the ability to alight gently, and in a limited space—an enormous advantage in foggy weather. Our own Government has taken a keen interest in the possibilities of the rotating wing. Soon after the Great War the Air Ministry started the experimental building of the Brennan helicopter. This was a four‐bladed device with a central engine and gear drive to two wing propellers. Much time and much money were consumed, but even after many years of effort the world was still without a helicopter which had made a cross‐country journey of even 10 miles; and I might have named a much shorter distance than that. Then there came the able young Spanish engineer, de la Cierva, with his autogiro and its ingenious and attractive system of hinged blades. To embark on the investigation of the rotating wing in flight is an entrancing adventure. The controls are different, new forces are brought into play, the technique of flight has to be learnt afresh. At the end of the research you may be no further on, so far as practical equipment is concerned, though you should be wiser; but there is always a chance that a pass may be found between the mountains of difficulty which will lead to the “Promised Land.” Most human adventures bring the adventurers in the end to the spot from which they started, and not infrequently the adventurers are content enough, after their hardships, that that should be so. Señor Cierva was adventurous to the point of temerity, and in the end he achieved what he sought—a new form of flying machine which really did fly. With great pertinacity he built machine after machine until, in the end, aided I am glad to add by British support, he constructed a machine which could fly across country in secure stages for thousands of miles. This, however, promising as it was, was not really the end of such a quest. A most difficult part had still to come, viz., the relatively humdrum requirement that the economics of autogiro transport must be such as to enable it to rival the conventional type of aircraft. In this stage we now are; it looks at present as though we may have to be content with a drop in top speed, rate of climb, and fuel economy in order to reap the great advantages of the autogiro in respect of safe landing. In striking this balance of merits, it must be borne in mind that the great advantage of safety in landing is now claimed also by the conventional type merely unconventionalised to the extent of being fitted with the Handley Page auto‐slots. If the rotating wing should fail to make good through the autogiro, will it do so through the Isacco helicogyre? This machine is an autogiro in which each of the four blades carries a small engine and airscrew. One is being built in this country, and is expected to be ready for flying tests this year. Such a machine, if it flics at all, should be able to ascend vertically as well as descend vertically. If it did this successfully at not too great an economic cost it would have merits with which the conventional type of aircraft, slotted or otherwise, would find it difficult to compete. But the path is likely to be long and difficult. In the last twenty years or so there has been time to discover and correct most of the bad habits of the ordinary airplane. British civil aviation as represented by Imperial Airways has had not a single fatal accident to any passenger for over three years—a splendid record. With these new flying machines we have to start again, and to start from scratch—to discover painfully and irritatingly how many little things there are to go wrong when there is no previous technique to guide us. With the autogiro most of our trouble, almost all of it, has been due to small breakages or failures of parts subjected to forms of stress not met with in any previous machines, whether for flying or for anything else.

THE achievement of a reasonable degree of silence in aircraft cabins is chiefly difficult because of the amazing intensity of the noise made by the airscrew and engine. There is, in addition, the difficulty of excluding this noise from the cabin without unduly adding to the weight of the structure.

THE following list of contracts placed by the Air Ministry during March is extracted from the April issue of The Ministry of Labour Gazette:—

The first edition of Prof. Bairstow's treatise appeared in 1920, and was largely based on experimental and theoretical researches carried on at the National Physical Laboratory immediately before and during the Great War of 1914–18. During this early period chief attention was given to three things:

The third term has been expressed as but in wind tunnel work it is often more convenient to measure were the omission of the dash signifies that the moment is now measured about a wind axis. The two quantities are very closely related and the measurement of one tells us almost as much as if the two were known. The latter, however, tells us either directly or indirectly what effect the addition of fin and rudder will have on the autorotation properties of the wings alone. The damping of fin and rudder being due essentially to the air flow meeting them at an angle on account of the rotation it should theoretically be possible to deduce this dynamic quantity from a simple static test of moment due to yaw angle. An experiment to test this was carried out several years ago but the static test did not give any approximation to the truth. This was ascribed at the time to the shielding of fin and rudder by the tail plane in the rotative experiment and subsequent work has amply confirmed this view. It is now known that shielding by the tail plane is by far the most important factor in determining the efficiency of the vertical surfaces at high angles of attack.