bluuebunny/crossref_metadata_2025 huggingface dataset:
Planning Fire Insurance—II
Authors: Gribble F.H.
Published: November 2014

IN the previous article an attempt was made to convey in general terms the background upon which fire insurance matters function, and deal with the salient points which attract the Fire Surveyor's special attention. It is intended in the present article to continue on more practical lines and deal with such matters as the isolation or restriction of “danger” spots, in order to avoid the fire insurance rating applicable to such points being used as the rating for other occupations or processes which in themselves would have been subject to a lower rating had the lay‐out of the premises enabled the more hazardous sections to be cut off by structural means and separately rated. In other words, if fire insurance experience was called in before final decisions were taken on a lay‐out, then the practical experience of experts gained, not only from experience of fires but from practical tests of the habits of various building materials when subject to fire conditions, assistance would be available in avoiding the many errors which cannot be remedied when the premises are finished, except at high cost. The alternative to this is to pay premiums higher than otherwise would have been necessary and, what is worse, the whole premises may be subject to the highest inception of fire hazard where freely communicating buildings obtain, which could have been avoided. No two premises are of course identical in size or use, but nevertheless it is hoped to convey the necessary considerations which can be generally applied.
Monocoque Stability in Compression
Authors: Lockwood Taylor J.
Published: November 2014

IN R. & M. 1679 and AIRCRAFT ENGINEERING, December, 1935, the author gave certain expressions for the stable loads which a stiffened‐skin panel, flat or curved, was capable of carrying without collapse by buckling. As regards the curved panel, it was there implicitly assumed that waving over relatively long lengths was impossible, because of the presence of rigid bulkheads or similar supports at intervals. While this will normally be the case in practice, it may happen that in some part of the structure a long length of panel remains without support other than that given to it by the ordinary frames and stringers. As this will tend to reduce the buckling load, it seems desirable to complete the theory to include the case of buckling in long waves.
Shear Stress in Thin‐Walled Tubes
Authors: Ovenston C.K.
Published: November 2014

THE shear stress in thin‐walled tubes is often a design criterion and considerable weight economy can be effected by an exact stress determination. The problem has been investigated by D. Williams, and the principle is here elaborated and extended to form a practical and very general method which enables many types of structure to be dealt with, such as slats, ailerons, monocoque and semi‐monocoque wings, fuselages and tail‐units in which the following diversities are encompassed:—
Constant‐Velocity Aerofoils
Authors: Lockwood Taylor J.
Published: November 2014

FOR aerofoils intended for use at high speeds, it is evident that the maximum lift on the back, consistent with a given maximum intensity of suction, will be attained when the suction, and hence the velocity, over the back is uniform; in other words, for a given mean lift on the back, the greatest suction will be a minimum, and so will the greatest velocity. On the hypothesis that compressibility stalling and compressibility effects generally depend on the amount of the greatest velocity at any point, such an aerofoil will have the ideal shape for high speed work. Interest, therefore, attaches to the theoretical solutions which are possible giving the form of an aerofoil having this property, particularly in view of the success of the theory in predicting velocity and pressure distributions for the ordinary range of aerofoils. When the thickness is finite somewhat involved problems in conformal representation require to be solved, although there is no fundamental difficulty in working out the solution. For thin aerofoils of small camber, such as those considered by Glauert in his classical theory, the problem is much simpler and it is known that the results of this theory are actually applicable to aerofoils such as are used in practice. Glauert himself considered only the case of infinitesimal thickness; this gives one solution of the problem here considered. Others are obtained by extending the theory to thicknesses of the same order as the camber, the order of approximation remaining the same. A particular case which will be treated here is that of an aerofoil having a flat face, i.e., camber equal to half the thickness.
Rotary‐Wing Aircraft
Authors: Bennett J.A.J.
Published: November 2014

IN the theory of the rotaplane developed by Glauert (ref. 20) certain terms are neglected which become important at small angles of incidence of the rotor, i.e., at high forward speed. Lock (ref. 16) has removed some of the approximations in Glauert's theory and obtains the same expression for the profile drag as is given in Appendix I of reference 20, which Glauert derived by consideration of the energy account. This expression, viz.,
Stressing of Airscrew Blades
Authors: Owen J.B.B.
Published: November 2014

THE estimation of the stresses in airscrew blades presents difficult aerodynamic and structural problems, the solution of which often involves considerable labour even after simplifying assumptions have been made. The aerodynamic problems associated with airscrew design have received considerable attention and extensive wind tunnel tests have been made, but on the other hand, the literature on the elastic problems presented by the airscrew is nothing like as extensive, and is mainly concerned with the twisting of the blades and the frequencies of blade vibrations. There then appears to be some justification for taking the present opportunity to concentrate on the strength side of airscrew design, dcaliug especially with the blade bending stresses which arise. On this account methods of estimating the air loads on the blades will not be dealt with here, where it will be assumed that the distribution of the air loads on the blades is known.
The I.Ae.S. Annual Meeting
Authors: Klemin Alexander
Published: November 2014

THE annual meeting of the Institute of the Aeronautical Sciences was, as usual, widely attended by representative members of government departments, the aviation industry and the Universities.
“Submerged” Engine Installations
Authors: Beall Wellwood E. , Emery E.G.
Published: November 2014

IT is rather difficult at this time to ascertain whether or not all the problems with which we are confronted in laying out “sub‐merged” engine installations are real or imaginary. We must contemplate the problems that we think exist and attempt solutions based mostly on our own past experience. Very few submerged engine installations have been designed, ground tested, or flown; therefore, actual experience is woefully lacking. The problems which we have encountered have been met while making preliminary designs of several types of advanced aircraft.
Optimum Climb to Height
Authors: Corner J.
Published: November 2014

TWO distinct types of climb arise in aviation. In the first, it is necessary to climb to a given height without attaching any importance to horizontal distance covered. An example is a climb to take up patrol at a given height. Obviously the quickest way to do this is to climb at the maximum rate of climb possible at each instant. The second type of climb is more important. In this it is necessary to climb to cruising height while, at the same time, travelling as far as possible in a certain horizontal direction. Examples are the initial climb of transport 'planes and bombers, and the “chasing climb” of a fighter which has taken off to pursue an enemy. It seems possible that the first type of climb is not the best in this case; a flatter climb, such as that shown dotted in Fig. 1, may have a horizontal speed sufficiently great to more than compensate for the extra time required to reach cruising height—vertical distances are exaggerated to show more clearly.
Modern Wooden Construction
Authors: Weyl A.R.
Published: November 2014

COMPRESSED laminated (“ improved ”) wood is generally counted among the hardening laminated plastics; it is built up from a large number of very thin veneers (0.0–1.005 in.) which are arranged with parallel grain directions. With the use of thermosetting synthetic resins, the veneers are highly compressed between hot platens. The adhesive, normally of the Bakelite type, is also a strengthening agent, or, with material of high resin content and high density, the wood may be considered as more or less a carrier for the resin, the latter being in this case the main strength‐producing agent.
Modern Wooden Construction
Authors: Weyl A.R.
Published: November 2014

Adhesives of this kind have in recent years become increasingly important for aeronautical purposes. This has been a consequence of the gluing processes adopted in German aircraft manufacture about 10 years ago. Although the application of phenole formaldehyde (bakelite) adhesives for plywood manufacture had already been investigated during 1916–1918 in this country, and although these adhesives were highly recommended by the Adhesive Research Committee in its Report of 1922, every further research and any intended use of adhesives of this kind was discontinued shortly after the war. This is a good example of the slowness in adopting progressive methods in wooden construction.
Models in Aeroplane Design
Authors: Taylor J.
Published: November 2014

THE increasing size of modern aeroplanes leads to an increasing difficulty in the performance of full scale tests for the determination of strength and stiffness characteristics. The use of models for the investigation of aerodynamic properties is a well established practice and it may soon become necessary to use them for the study of strength and stiffness properties also.
The I.Ae.S. Annual Meeting
Authors: Klemin Alexander
Published: November 2014

THE Annual Meeting proper was preceded by the Honors Dinner at which several awards were given for distinguished achievements in aeronautics. The Daniel Guggenheim Medal itself was presented to Glenn L. Martin, an early aviation pioneer, whose Baltimore plant is turning out patrol bombers, the B‐26, an advanced medium bomber, and the Baltimore's medium bomber specially designed for British needs. Mr. Martin is the last survivor of the American aeroplane pioneers to head an aircraft manufacturing company bearing his own name. William J. Knudsen was among the distinguished guests. The guest of honour was Griffith Brewer, President of the Royal Aeronautical Society of Great Britain, who called for speedy help to Britain in its hour of need. If the enthusiastic greeting given to Mr. Brewer is any criterion, then it may be taken for granted that the aviation fraternity of the United States is heart and soul with the British stand.
Fatigue Tests on Duralumin
Authors: Guildford Hoskins H.
Published: November 2014

IT is well known that many materials, including wrought and heat‐treated duralumin‐type alloys, when subjected to fatigue tests in machines employing different stressing and straining actions, may give consistent results under each set of conditions, but the results will not agree from one set of conditions to another. Differences in the form and size of the test piece may also have an effect on the results of fatigue tests. This note discusses certain aspects of the problem of why such differences in test conditions can cause differences in the results of fatigue tests.
Helicopter Design
Authors: Lockwood Taylor J.
Published: November 2014

REPORTS from America speak of flight tests of two types of screw‐lift aircraft, the Sikorsky multi‐rotor machine, and a twin‐rotor type. From this it would seem that the day of the practical helicopter, so Ions foreshadowed, is not far distant. The following general notes on design considerations may therefore be sufficiently topical to be of interest.
The Eccentric Circular Tube
Authors: WILSON T.S.
Published: November 2014

THE problem of the strength and stiffness of an eccentric circular tube or shaft has not, to the writer's knowledge, received attention in the ordinary engineering text‐books. This is somewhat surprising in view of the fact that exact concentricity is not easily obtained in long shafts, During war‐time, when highly skilled labour has to be supplemented by that of scantily trained and in‐experienced men and women, it is unfortunately only too likely that engineers will frequently have to decide whether an eccentrically drilled shaft may be passed for service.
Frequency Equations
Authors: Morris J.
Published: November 2014

IN the article on simultaneous equations published in AIRCRAFT ENGINEERING, Vol. XI, May, 1939, pp. 199–200, the author exploited the powerful process of iteration. In the present article he deals similarly with an iterative method for finding the roots of a determinantal equation. Such a method was first given by Duncan and Collar in their paper “On a Method for the Solution of Oscillation Problems by Matrices” (Phil. Mag. Vol. 17, p. 865, 1934), and embodied in the book, “Elementary Matrices,” by Frazer, Duncan and Collar (Cambridge, 1938), reviewed in AIRCRAFT ENGINEERING, Vol. XI, February, 1939, p. 55. The particular treatment here adopted has the advantage that it is founded on elementary algebraic principles.
Torque on Engine Mountings
Authors: Graham C.D. , Tembe N.R.
Published: November 2014

MODERN aeroplane design necessitates the use of high powered engines, frequently used in conjunction with large diameter airscrews and low reduction gear ratios. This, causes very high torque loads on the mounting, these loads often being greater than those due to any other causes. Obviously then, the distribution of these torque loads must be found accurately for they have an important bearing on the efficiency of the final design. The following analytical method of determining the distribution has been found both convenient and accurate.
Inspection of Bearing Surfaces
Authors: Twelvetrees W.N.
Published: November 2014

WHEN man invented the wheel, bearings were introduced into civilization and every machine since devised incorporates, in some form, means of sustaining a loaded member in motion by another fixed member. It is not surprising, therefore, that examination of bearings forms a high proportion of all engineering inspection and the phrase “to look at the bedding of the bearing” is probably one of the oldest in engineering practice. During recent years, particularly in the aircraft industry, developments have taken place in bearing design and bearing metals which require an inspection technique differing from conventional methods that served well when loadings were comparatively low and factors of safety high. Desirable clearances and surface condition of the earlier alloys will not answer at all well for some new bearing materials; while on the other hand defects such as minor cracks, which were very dangerous in white metal, have been proved by experience to have little or no effect on some heavily loaded lead bronze bearings.
Air‐Line Engineering Management
Authors: Lusty Ivor
Published: November 2014

THE production and marketing of aerial communication and transportation is, as yet, a young industry. It has at its call the experiences of past years of similar and allied undertakings, which form a background or framework upon which to build its structure, but for the remainder there is, technically, no help but self‐help. Financial assistance there may be from the government of the country served, but the technical problems peculiar to maintaining and operating an air line await for their solution the technical skill of, the air lines' personnel.
Resistance of Wood to Impact Loads
Authors: Pettifor C.B.
Published: November 2014

FOR most of the uses to which timber is put, reasonably good resistance to impact is an advantage; for many uses, such as aircraft construction, sports goods, or tool handles, it is an overriding requisite. Its measurement is, therefore, an important part of the routine testing of timber. Since conditions of service as regards this property are seldom, if ever, known with exactitude, and since, moreover, the size and shape of the member receiving the impact bear an important but undefined relationship to its resistance, the laboratory tests for the property are essentially empirical. The resulting figures from such tests in themselves mean little; they cannot be translated into design figures as are, for instance, modulus of elasticity or maximum compressive strength; and their value lies almost entirely in their use for comparisons. As with most empirical tests, one of the essentials is that the character of the test, i.e. test‐piece and testing conditions, shall be rigidly defined and adhered to. Unfortunately there are in more or less common use in the various timber testing laboratories several different methods of measuring impact resistance and the lack of a universal standard impact test is a serious drawback to the usefulness of the results, since one of the greatest advantages of the standardized test, viz., the interchange‐ability of results between one laboratory and another, is at once nullified. It is hoped that when circumstances permit the interested research institutions will take up the study of impact testing and agree upon a uniform standard test.
Air‐line Engineering Maintenance
Authors: Lusty Ivor
Published: November 2014

THERE are at work, in any industrial enterprise, economic laws, which when removed from their environment and exposed as pure principals are so immediately evident that elucidation is almost superfluous. However, it is only by a clear appreciation of these things in their pure form that they can be logically manipulated when applied, so to this end some explanations will be given here.
Two‐Spar Wing Stress Analysis
Authors: Goodey W.J.
Published: November 2014

Effect of Tensile Stresses in the Bottom Skin WE now come to the investigation of the effect of tensile stresses in the bottom skin. In this case, the analysis is necessarily more complicated than the preceding, but it will be found that the mathematical work is essentially the same, and that we have the same basic equations simply with more terms in them. In particular, the condition for minimum strain energy is the same as equation (9), but the expressions for X and Y are more complicated. As before, the quantity Y depends only on the structure of the wing, while X depends on both the structure and the applied loads. The quantity Z is the same as before.
Quality Control in Production Engineering
Authors: Rissik H.
Published: November 2014

THE statistical method of controlling product quality during manufacture—a technique commonly known by the shorter title, Quality Control—is a very recent development in the field of production engineering. In point of fact the first application of this technique to machine‐shop production in this country took place late in 1940 at the Croydon works of Messrs. Creed & Co. Ltd., a firm whose name is a household word in electrical communications, for the Creed teleprinter is known all over the world. At the same time it must not be thought that quality control as such, or the use of the so‐called quality control chart as an aid to manufacture, is a purely wartime development. Statistical methods have been employed in British industry, notably in electric lamp manufacture, and in the production of both cotton and woollen textiles, for more than fifteen years, whilst the technique of quality control itself was originated by Dr. W. A. Shewhart of the Bell Telephone Laboratories, New York, in 1922. But where engineering practice was concerned, the application of statistical methods did not present itself until quite recently as a necessary or even convenient solution of manufacturing difficulties.
Analytical Geometry in Common Layouts
Authors: Garvey S.J. , Hetzel K.W.
Published: November 2014

EXPERIENCE has shown that the common method of “laying out” geometrical problems on the drawing board leads to a large expenditure of man‐hours and, in general, a result of doubtful accuracy. This loss of accuracy is aggravated by scale, and results on large structures may be inaccurate by a prohibitive amount. Use of analytical geometry may be said to have two major advantages, therefore, (a) Less man‐hours required for the job, (b) Any desired standard of accuracy may be obtained.
Analytical Geometry in Common Layouts
Authors: Hetzel K.W. , Garvey S.J.
Published: November 2014

FOLDING wings of the type employing a skew—hinge axis present a somewhat difficult lay‐out problem in way of the wing cut. The problem with which this article is concerned is that of obtaining, in the form of vertical spanwise sections, the surface swept out by one cut edge of the folding portion as the wing rotates. This enables the bottom cut line to be determined when the top cut line is known, or vice versa. If the leading edge rises when the wing folds, the top cut line will be determined by the fully folded position; if the leading edge falls, it will be the bottom cut line that is thus determined. The following diagrams and calculations are made for the rising leading edge type; the same method may be applied to the falling leading edge type viewing the wing upside down. A numerical example is worked along with the theory.
The Lateral Stability of Aeroplanes
Authors: Price H.L.
Published: November 2014

IN the previous article, the lateral stability of an aircraft was shown to depend upon the roots of a quartic equation in which the coefficients were obtained in terms of the resistance derivatives of the aeroplane. These derivatives were defined in a highly synthetic manner from a mathematical rather than a physical standpoint, so that their meaning is apt to be somewhat obscure. It is likely, however, that the use of symbols like lp is familiar to readers who are not otherwise acquainted with stability nomenclature, since these expressions arc commonly used in other aerodynamic topics such as rolling performance, spinning etc. It is important therefore to correlate the definitions given here with those given elsewhere and to establish their physical meanings.
The Problem of Wing Oscillation
Authors: Krzywoblocki Zbigniew
Published: November 2014

THE steady increase in speed and use of thin aerofoils compels a deeper consideration of the problem of oscillation. In recent years there has been a tendency to the building of large aeroplanes. This is closely connected with the problem of oscillation. The author in a first approximation tries to solve, from a proportionality point of view, the question of influence of kind of material and size of aeroplane on wing flexural and torsional natural frequencies. Following the idea of solving this problem from a qualitative and not from a quantitative point of view, the conception of proportionality instead of equality is introduced. The idea of “wing torsional rigidity” is created, being inversely proportional to the angle of twist at the end of wing. Applying Newton's Law, at first the flexural and torsional natural frequency of an oscillating rod is found. Afterwards the method is used in the case of an oscillating tubular member. The results are checked by Rayleigh's Method. Lastly, the influence of size of wings having similar shape is taken into consideration.
Ash Bark‐Beetle Damage
Authors: Fisher R.C.
Published: November 2014

THROUGHOUT the summer and early autumn, small piles of white bore dust on the surface of the bark of ash, English or imported, are a common sight in timber yards and dispersal sites. As the Forest Products Research Laboratory receives a number of inquiries every year on this type of insect attack, the following information may be useful to all who may be alarmed by its presence in their stock.
The Lateral Stability of Aeroplanes
Authors: Price H.L.
Published: November 2014

VARIATION IN “TYPICAL VALUE” PARAMETERS IT has previously been shown that the effect of freeing the controls on the lateral stability of an aircraft may be taken account of by changes both in the values of the derivatives lp, lr, np and nr (wing), which hitherto have had typcial values, and also of the variables x, y and t themselves. It is therefore desirable to have information on the effect on the stability boundaries of changes in these derivatives. It may also happen that the values of yv and tan Θo in the case of a particular aircraft may be known to differ from those here adopted in the drawing of stability charts. The versatility of these charts (later to be given) will therefore be considerably increased if rules are expounded for assessing the effects of changes in any of those derivatives which were formerly fixed. This we proceed to do.
The Testing of Aircraft Thermometers
Authors: Barrington Brock R.
Published: November 2014

IT has become increasingly obvious that however good the thermometers may be in an aeroplane, they are liable to errors—sometimes quite large ones—as a result of vibration, fatigue or plain accidental damage. It seems quite likely that on operational machines an error, as long as it is constant, is of no great importance; as most pilots look for variations in their normal readings, rather than judge by the readings themselves, and, therefore, it is probably sufficient if any instrument that is obviously suspect is tested, and the others are‐taken as satisfactory.
Critical Reversal Speed
Authors: Horton W.H.
Published: November 2014

THIS article is intended, firstly, as a means to a quick approximate determination of the critical reversal speed of a wing, and secondly to give a clearer insight of why approximations can be given for the general formula for determining K, when the aileron chord and wing chord are of linear taper at least over the aileron portion.
Strength Factors of Steels
Authors: Fitzgerald‐Lee G.
Published: November 2014

WHILE considering the specification requirements of various steels, the possibility of graphically correlating the main factors occurred to the writer. At the first attempt, a correlation of ultimate tensile strengths with proof stresses produced, graphically, a sort of hyperbola; at the second attempt, by changing the vertical and horizontal scales, and working to average figures, the graph took the form of a straight line ending in a hyperbolic curve; at the third attempt the graph became a straight line with plotted points not exactly coincidental with the line; the fourth attempt produced the U.T.S./Proof Stress “curve” which is the subject of this paper.
UN SECRET DE POLICHINELLE
Authors: Lockwood Marsh W.
Published: November 2014

ON the seventh of this month the fact was officially announced that there have been for some time a number of British designed jet‐propulsion aeroplanes flying in England and America and that these have proved sufficiently successful for the type to be put into production. In spite of the widely‐spread knowledge of this development, the secret has been, except for one regrettable lapse, extremely well kept and such references to machines of this type as have appeared have been confined to the Caproni‐Campini aeroplane, news of the existence and flights of which was rather surprisingly released by the Italian Government over two years ago.
Some Notes on Pneumatic Tyres
Authors: Hadekel R.
Published: November 2014

TYRES get very little attention of the inquisitive sort from those whose business it is to incorporate them in the aircraft. The only information that is usually required (and given) is the load‐deflection curve (obtained experimentally) and the overall dimensions, and that is all that is necessary for most purposes. Yet a theoretical investigation of tyre behaviour should be useful from the following aspects:
Shear Stress in a Tapering Beam
Authors: Saksena G.B.
Published: November 2014

IN the course of stressing certain front cross members of an engine mounting it was found necessary to determine the shear'stress on various sections of the cross members as accurately as possible. These cross members were by no means of uniform cross‐section, so that it was considered desirable to investigate, a formula which would give shear stress in a tapered beam. The “classical” methods evolved by Messrs. Coker and Filon in their Treatise on Photo‐elasticity and by Mr. Atkin in AIRCRAFT ENGINEERING, Vol. X, November and December, 1938, pp. 347–351 and 371–374 were found to be too elaborate. In September, 1942, Messrs. Pugsley and Weatherhead contributed an article entitled “The Shear Stresses in Tapered Beams”, to the Journal of the Royal Aeronautical Society. These authors start with a standard expression for shear stress based on the equilibrium of a portion of a beam and apply it to the solution of some examples. In the course of my investigations, it has been found possible to extend the “engineering” analysis of shear stress in beams of uniform section to beams of variable cross‐section. The expression for the determination of shear stress thus arrived at is very convenient and quite suitable for graphical methods. However, in the case of symmetrically tapering beams, an approximate formula has been developed for the shear stress in terms of shear force, bending moment, taper angle and section inertia and this formula is much more convenient and simple to apply than the standard expression used by Messrs. Pugsley and Weatherhead.
Strength of Light‐Alloy Components
Authors: Beilschmidt J.L.
Published: November 2014

A FEATURE of many of the light alloys now in common use is that the stress and strain curve often does not evidence any well defined region in which the elastic strain becomes plastic strain, and a linear portion of the diagram from the origin, which in the case of so many metals represents a region of proportionality, is sometimes almost non‐existent, the diagram being curved right from the origin so that it is not possible to define any region or limit of proportionality, and the proof stress; by standard definition, has accordingly a relatively low value compared with the ultimate tensile stress of the alloy concerned. (Fig. 1).
The Acetylene Thermoplastics
Authors: FitzGerald‐Lee G.
Published: November 2014

THE object of this paper is to trace, with as few technical terms as possible, the main points of the various plastics belonging to the acetylene group, so that designers and technicians who have not the good fortune to be chemists may more easily understand the practical applications of these comparatively new materials.
Some Aspects of Wing Design
Authors: Smyth S.J.
Published: November 2014

IN selecting a wing to give the least possible drag at some predetermined speed the designer has three variables at his disposal, these being wing area, aerofoil section and aspect ratio. A fourth variable, taper ratio, is not considered in this article and will be assumed to be constant in any particular problem.
Mechanical Failures in Aero‐Engines
Authors: Twelvetrees W.N. , Walpole K.W.
Published: November 2014

FEW engineering products receive the abuse to which aero engines are subjected in wartime and few mechanical devices are produced in which the margin of safety and failure is so small and yet so vital. Failures on a large scale are, therefore, inevitable and their consideration in detail would present a task of prohibitive magnitude but what little is known with any completeness and certainty can offer some useful data. Consideration of a large number of different makes of engines overhauled during wartime has revealed an amazing complexity of facts; it has shown that failures have developed from almost every conceivable cause which, in turn, have produced every conceivable result. There are few tangible pronouncements which can be made on the subject but nevertheless distinct common tendency has been observed which is sufficiently consistent to be worth consideration. This concerns the general trend of failures and will be referred to later; but with regard to failures in detail, the only safe statement to make is that invariably different parts‐fail on different types of engines subjected to similar conditions of severity in operation. The reason for this is not hard to find, and complexity of design in modern aero engines prohibits the mechanical ideal of simultaneous failure of adjacent parts subjected to a given overload. Not only is the exact functional strength of each individual part hardly known but the loadings which it has to endure cannot be foreseen.
An Italian Artificial Horizon
Authors: Postlethwaite F.
Published: November 2014

AT this stage of the war it is most unusual for any considerable novelty to be discovered in the design of aircraft instruments. In particular this applies to the Artificial Horizon, whose use is almost universal, and all instruments of this type are usually a close copy of the standard Spcrry instrument. The Italian Artificial Horizon described in this article does, however, incorporate a number of new and novel features; for example, the indicating mechanism has complete freedom in both pitch and roll instead of the customary limited range of movement. Some general details are:
Electrical Equipment in Multi‐Engined Aircraft
Authors: Kearns T.
Published: November 2014

THE forbearance of readers is requested at the outset for a personal note, considered to be inseparable from the basic purpose of this paper. The author's professional duties for many years prior to this war were concentrated on the specialist work of the design of distribution and transmission networks of various electricity supply undertakings, covering the main development period of electricity supply in this country, and also including the change‐over of direct current consumers to alternating supply. The author was directed for the period of the war into the aircraft industry and again specialized on the electrical side, and the similarity of the technical problems which have arisen in both his experiences leave no doubt that aircraft electrical systems can benefit from the hard‐won success of the electricity undertakings, whose achievements and mistakes alike are given publicity and opportunity for discussion. The technical success of supply systems is generally admitted to be in a large measure due to the freely‐pooled contributions from the experience of engineers in the profession. The author airs very decided personal views, many of them contrary to present practice and forecasts, and in order that the criticism it is hoped to arouse should not be marred by any misunderstandings, it is made clear that his experience is limited to British aircraft; with no knowledge of American practice. The scope of electrical applications in aircraft is very great and it does seem that as each new application arises, those responsible endeavour to design suitable systems and apparatus de novo instead of ascertaining first whether or no there is a similar application in the electrical industry which has been tried out over the years, and which if applied with suitable modification to aircraft would cut out the inexcusable “teething” troubles. For example, the risk of fire being carried along by cables has been very thoroughly studied in switching stations; the deleterious effects of oil upon rubber insulation were appreciated years ago; and telephonic intercommunication has been utilized always in generating stations where the noise is quite equal to that which obtains in aircraft; also the practice of endeavouring to classify cables by their current carrying capacities was abandoned a very long time ago. These are only a few examples in which the author feels that aircraft electrical systems can be improved as a result of experience in the allied industry.
The Fundamentals of Flutter
Authors: Duncan W.J.
Published: November 2014

The Concept of Stability and Types of Instability THE term stable or unstable is applied to a body or system in accordance with the nature of the ultimate consequence of applying a disturbance. If the body or system is at rest and in equilibrium in a certain configuration, that configuration is said to be completely stable if the system ultimately comes to rest in the same configuration after the imposition of any disturbance. Frequently interest is confined to small disturbances; the term small is vague but must be interpreted as meaning that the motions of disturbance (or deviations) are so bounded that they can be described by linear differential equations. When this is so, the investigation of the stability becomes relatively easy and the actual magnitudes of the initial disturbances are not required in the discussion of the stability. The same concept of stability for small disturbances can obviously be applied to any steady motion and indeed to any regular motion. The criterion for stability is that the deviations from the basic motion consequent upon a small disturbance shall ultimately become vanishingly small.
Rings for Two‐decked Fuselages
Authors: Beskin Leon
Published: November 2014

INTRODUCTION WITH the current trend toward the in crease of the dimensions of aeroplanes, many two‐decked aeroplanes are being designed.
Tailless Aeroplane Control Systems
Authors: Weyl A.R.
Published: November 2014

WITH tailless aeroplanes, all known aerodynamic control devices possess the peculiarity of not only producing moments about one axis, but of also causing secondary moments about one or both of the other axes. Horizontal controllers forming part of the wing near the tips in wings having sweep‐back or sweep‐forward, for instance, do not produce rolling moments alone, when differ‐entially deflected; they also cause yawing and pitching moments. Similarly, wing‐tip disk rudders operated on such wings not only produce yawing moments, but may cause rolling and even pitching moments.
Standard Atmospheric Conditions
Authors: Saksena G.B.
Published: November 2014

ALL aircraft and aero‐engine performance calculations are reduced to an agreed Standard Atmosphere defined by the International Commission on Air Navigation in order that direct comparison between the results can be easily made. But for design purposes, especially the design of radiators, this Standard Atmosphere is neither universally adopted nor suitable. Other most commonly used atmospheric conditions in this country are the Temperate Summer and the Tropical Summer. Some of the properties of these atmospheres are given in various Air Publications issued by the Ministry of Aircraft Production, including It. & M. 1891, and can also be found on p. 179 of the Meteorological Glossary (third edition) issued by the Meteorological Office. Unfortunately, the functions tabulated in these publications are inadequate for practical purposes except in the case of the I.C.A.N, atmosphere where all the commonly used functions are given in “Physical Properties of the Standard Atmosphere” by Messrs Pankhurst and Conn in R. & M. 1891. It is, therefore, proposed to fill up this gap and to give functions commonly used for Temperate Summer and Tropical Summer atmospheres on lines similar to those used in R. & M. 1891.
Deflexion of Tapered Beams
Authors: Tatham R. , Price H.L.
Published: November 2014

IN the following investigation we consider the deflection due to bending of a tapered cantilever beam carrying concentrated end and lateral loads at the free tip. The mode of taper of the beam is assumed of a generalized form, and is such that the second moment of the area of the cross‐section at any point varies as the nth power of its distance from the unsupported vertex. Detailed calculations are given for the cases n = 1,2,3,4 corresponding to the types of beams most commonly arising in practice. It is shown that fairly substantial errors may arise if the commonly used approximate treatments are adopted. The theory may also be extended to yield the value of the critical end loads for tapered struts conforming to any value of n.
Simplified Two‐Dimensional Aerofoil Theory
Authors: Brennan M.J. , Stevenson A.C.
Published: November 2014

THIS article derives from one of similar title by H. J. Stewart, in which he gave an account of a simple method of dealing with thin aerofoil theory for small angles of incidence by satisfying the usual approximate condition at the boundary of the aerofoil after expanding the slope of the profile in a Fourier series.
Stress Diffusion Problems
Authors: Goodey W.J.
Published: November 2014

WE now come to the case shown in fig. 14. This is intended to represent a simplification of a two‐spar wing, having an outer portion skin‐covered and an inner open portion, the two spars being built‐in at the inner end. The top and bottom skins will usually be reinforced with spanwise stiffeners and the application of torque to the box will induce end loads in these stiffeners, in addition to bending moments in the spars. These end loads are essentially a local effect, localized near the inner end of the skin‐covered portion of the wing, and at sections remote from the inner end the torsional stresses in the box will be given by the ordinary Batho formula.
The Compressive Strength of Short Circular Tubes
Authors: Bowen I.G.
Published: November 2014

DOUGLAS and Carmichael (REF. 1) have suggested formulae relating the compressive strength at failure of short circular tubes with their ultimate tensile strength and thickness/radius ratio. Robertson (REF. 2) has tested Southwell's theoretical formula for thin‐walled circular tubes. Further tests on medium and thick tubes by the author have indicated that the new data and that of Douglas and Carmichael can best be correlated by the inclusion of yet another property of the tube material. The representation, within the specified limits, is extremely good and taken in conjunction with existing data on thin tubes, the strength of tubes under this loading condition can be predicted over a wide range of material properties and geometrical dimensions. Also included in the author's data are extensometer tests over the elastic and early plastic regions of compression. A comparison of the resultant proof stresses with those of control tensile tests verifies their equality except under certain interesting conditions.
The Performance of Rotating‐Wing Aircraft Rotors
Authors: Toms C.F.
Published: November 2014

THIS paper presents a summary of the method and results of a general investigation into the performance characteristics of ‘single’ autogyro and helicopter rotors, which was a preliminary to the establishment, by the firm the author serves, of a helicopter division.
The Repair of Avro Aircraft
Authors: Chad wick Roy
Published: November 2014

THE policy and organization of the Avro Repair Group was based upon intelligent anticipation—anticipation of the many and varied types of damage that might be expectedl anticipation of quantities, and anticipation of facilities to deal with all contingencies. The central depot at Bracebridge Heath, Lincoln, developed from an ex‐1914–18 war hangar to an establishment employing nearly 3,000 men and forming the hub of an organization that embraced many stations and subcontractors' works, civilian out‐working parties, of A. V. Roe personnel, effected a high proportion of major repairs to Lancaster, York and Anson aircraft; such parties were stationed all over the British Isles and were supplemented by a fleet of some seventy mobile workshops.
Aircraft Rocket Motors
Authors: Baxter A.D.
Published: November 2014

THE rocket motor is a form of jet propulsion which is characterized by independence of the external atmosphere for combustion, relative independence of altitude and flight velocity upon thrust, small frontal area for high thrusts, simple construction and low weight, and high rate of fuel consumption. Its use was greatly developed during the war years and many applications are now familiar to all. Most of the work on rocket missiles, such as the anti‐aircraft barrages, fighter armament, etc., was performed with solid fuel rockets, but liquid fuels were developed by the Germans for the well‐known V.2, for the Me. 163 aircraft, the Henschel glide bomb and various other applications. They concentrated a great deal of effort on this work and considerable technical progress had been made with different systems. Three main systems emerged and these were distinguished by the oxygen bearing fluids they used. The fluids were:
The German Development of Recoilless Guns for Aircraft
Authors: Corner J.
Published: November 2014

RECOILLESS guns have been developed in Germany, Russia and America because of the lightness of the whole equipment, relative to the muzzle‐energy, that is possible in this class of gun. The German work began about 1937 and such guns (10·5 cm. L.G.40) were used in the invasion of Crete in 1941. The Russian 3‐inch recoilless gun was in use a little earlier. American interest in these guns dates from 1943, and a 7·5 cm. type has been announced. No British recoilless guns have been mentioned, but a theory of the internal ballistics of this form of gun has been published recently by the present writer.
Design and Production Technique
Authors: Schroeder A.J.
Published: November 2014

(1) Casting technique comprises the methods of working in which liquid metal is poured into moulds.
Design and Production Technique
Authors: Schroeder A.J.
Published: November 2014

FIG. 67: The by‐work for fixing the cores (a) and (b) is complicated owing to the undercutting (u) and the projection (p). The joint securing of both cores is difficult. The cores or the mould are easily damaged. The necessary patchwork means additional expense.
The Machining of Stainless Steels
Authors: Crisp W.H. , Burnan W.
Published: November 2014

FROM a machinability aspect, stainless steels may be classified into three categories, the general analysis of which influences the machinability factor.
Undercarriages for Deck Landing
Authors: Blinkhorn J.W.
Published: November 2014

FOR landing on aerodromes, aircraft under‐carriages are now designed to give a certain safety factor on strength for specified conditions. These conditions have been determined after considerable investigations and represent the most severe landings that aircraft can reasonably be subjected to, and are defined in terms of the ground reaction applied to the wheels when the aircraft touches down at a specified arbitrary vertical velocity of descent in an airborne landing; i.e. the aircraft weight balanced by the aero‐dynamic lift on the wings. In a normal landing, of course, the aircraft is seldom 100 per cent airborne, but this assumption is a sufficiently accurate approximation. The vertical component of this ground reaction may be associated with various components of drag and side load, to cover for example the drag loads due to spinning up the wheels on surfaces with various coefficients of friction, ground ‘bumps’, drift, etc.
An Analysis of Range for Aircraft Project Design
Authors: Stratford A.H.
Published: November 2014

THE various flight procedures for medium and long range operation of transport aircraft are described, and the constant power basis is shown to be advantageous for airscrew‐driving power units when comparisons are required in the design study stage. To avoid the approximation involved in assuming a cruising speed which is a mean of the initial and final speeds and likely to introduce errors when the fuel load is an appreciable percentage of all‐up weight, a method is presented which by means of a chart enables the true Still Air Range to be evaluated.
The Laminar Boundary Layer
Authors: Piercy N.A.V. , Whitehead L.G. , Tyler R.A.
Published: November 2014

THE greatly increased transition Reynolds numbers now attained in the boundary layers of cylinders having favourably shaped sections have renewed interest in the solution of the equations of steady flow in a thin boundary layer. It is familiar that the scries solutions of Blasius and Hiemenz, improved by Howarth (ref. 1), and of Falkner (ref. 2) become severely restricted in range when applied to cylinders having other than bluff sections. But it appears that a series solution of substantially greater range is possible, at least for symmetrical flow, provided that the nose of the section is rounded. This problem forms the subject of Section I of the present paper.