bluuebunny/crossref_metadata_2025 huggingface dataset:
The Manufacture of Tubes for Aircraft
Authors: Hackett W.
Published: November 2014

THIS article is representative of tube manufacturing practice in general, but mainly deals with the tube range of Accles & Pollock, Limited, and its application to aircraft.
Manufacturing Tolerances
Authors: Parkinson H.
Published: November 2014

THE primary consideration in establishing a set of limits for use in the manufacture of any engineering product must always be closely related to the quantity of parts, or units, to be produced. Thus, the component parts of a motor car will be produced in quantities which warrant the manufacture of expensive jigs and tools, these being made to a precision, where demanded, far beyond that to be expected for parts which are other than mass produced. Diametrically opposite to this we have the case of an experimental aircraft, or similar engineering project, which will be produced to limits which are dependent upon the skill of the operatives in making the component parts without the aid of jigs, templates, etc.
Simultaneous Equations
Authors: Morris J.
Published: November 2014

MANY problems in engineering science resolve themselves into the solution of simultaneous linear equations. In general when more than three variables are present these equations tend to become troublesome to solve; their numerical solutions besides being tedious frequently involve differences between quantities very nearly equal, so that unless the calculations be carried to several significant figures considerable errors are likely to arise in the results. To overcome this difficulty recent research has been directed towards the development of approximate and successive approximation methods suitable for routine application. The most promising method appears to be that based on iteration. Such methods were originally given by Gauss and Seidel. In R. & M. 1711 the writer put forward an iteration process which has the advantage of being carried out in a simple tabular form and in which the iteration is carried out not with current values of the variables, but with the differences of consecutive current values. The iteration method is only applicable when the coefficients of the variables satisfy certain conditions which will be discussed in the sequel. For the present the convergency of the process will be assumed.
An Elementary Study of the Spin
Authors: Crowe J.H.
Published: November 2014

There are several methods available for either preventing autorotation or reducing the autorotation speeds. There are special devices available such as slots or Schrenk slits, or the ailerons themselves may be used for this purpose. Once the designer has selected his plan form, etc., he can have a variety of aids to hinder the rotation of the machine about the longitudinal axis. The tendency to‐day is to eliminate such extraneous devices since the designer is loath to fit any arrangement which involves any complication such as moving parts or any increase in weight. He is content to rely for the most part on his experience in assessing the relative merits of various degrees of taper and tip sections, etc., and to assume that if he can dispose of wing dropping the autorotational characteristics of his wing will be satisfactory. This is not by any means a reliable guide at the coarser angles of incidence of a spin.
An Elementary Study of the Spin
Authors: Crowe J.H.
Published: November 2014

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.
Structural Research in Aeronautics
Authors: NORTH JOHN D.
Published: November 2014

To the Editor. SIR,—I feel that I must write a few lines to congratulate you and Dr. Pugsley on his article on “Structural Research in Aeronautics” published in your June issue.
Surface Finish and Performance
Authors: Young A.D.
Published: November 2014

IN order to appreciate how surface finish affects drag one must be familiar with the main characteristics of boundary layer flow. These have been described in great detail elsewhere, see, for example, Ref. 1, but a brief outline will not be out of place here. At the surface of a body moving through air there is a thin layer of air called the boundary layer in which the velocity relative to the body rapidly falls to zero as the surface of the body is approached. Because of the large velocity gradients across the boundary layer the viscous forces are appreciable there; outside the boundary layer the flow approximates closely to the ideal inviscid flow of classical hydrodynamics. The flow in the boundary layer beginning at the forward stagnation point is usually laminar for some distance, then after a transition region the flow becomes turbulent. The transition region is appreciable in extent at low Reynolds numbers and in turbulent airstreams, but at the Reynolds numbers usual in flight it is short enough to be referred to as a point. Wo now know enough about both laminar and turbulent types of flow over smooth surfaces and the associated frictional forces to be able to calculate with fair accuracy the profile and skin friction drags of a smooth aerofoil given its thickness, Reynolds number and the position of the transition points2. It is found that the skin friction in the laminar boundary layer is much smaller than the skin friction in the turbulent boundary layer; this is illustrated in Fig. 1, which shows the skin friction distribution on one side of a smooth flat plate at a Reynolds number of 107 and with the transition points at 05 c. and 25 c. Fig. 2 shows the variation of drag with the position of the transition point for the flat plate. Similar curves are obtained for aerofoils and bodies of revolution. It is evident that the further back transition occurs the less will be the drag. Fig. 3 illustrates a point that is worth emphasizing, namely, the relative importance of the drag change due to a given transition point movement increases with wing thickness and Reynolds number.
Rotary‐Wing Aircraft
Authors: Bennett J.A.J.
Published: November 2014

THAT the rotaplane rotor is essentially a windmill has hitherto been regarded as self‐evident. It will be shown in the following analysis that, when the profile drag is sufficiently small, only part of the rotor is in the “windmill brake” state. This part receives more torque from the air than can be expended in profile drag and therefore the rotaplane rotor at zero torque must be partly an airscrew in the “vortex ring” state.
Solid Organic Materials
Authors: de Bruyne N.A.
Published: November 2014

CELLULOSE is Nature's strong material. It is the chief constituent of cotton flax and wood. Wood can be turned into sugars by treatment with hydrochloric acid Bergius process) and by certain termites; horses and cows break down the cellulose in grass into sugar before digesting it. So it is not surprising that the cellulose polymer is built up of what are practically molecules of a glucose (“Barley Sugar”). Each β glucose unit is twisted about its axis through 180 deg.; the combination of two such units makes up that is called a cellulose unit which has the structure shown in Fig. 2. The cellulose polymer is a long, straight chain made up from these cellobiose units, and each chain probably contains about 70 such units.
Rotary‐Wing Aircraft
Authors: Bennett J.A.J.
Published: November 2014

THE calculation of the natural frequencies of oscillation of an articulated rotary‐wing system presents considerable difficulty owing to the large number of variables which require to be taken into account and it is proposed to consider first of all the simplified system of a mass rotating about a fixed axis and connected to it through two hinges, the axes of which are inclined to one another but lie in parallel planes perpendicular to the arm connecting the two hinges. In the next article an approximate method will be given of obtaining the natural vibrations of an articulated rotary‐wing system.
Solid Organic Materials
Authors: de Bruyne N.A.
Published: November 2014

SYNTHETIC AND OTHER PLASTICS CELLULOSE and rubber are made of long chain molecules already built up for us by nature, but in recent years we have learned to make synthetic polymers with physical characteristics not unlike those of natural polymers; the variety of such synthetic polymers is already somewhat bewildering, and it is quite certain that chemists have only made a beginning in an exploration that promises to be as successful as anything achieved by the classical organic chemists of the nine‐teenth century. Like many other branches of knowledge the subject is easier to understand if not treated in the chronological order in which the discoveries have been made. We will therefore begin with a description of the vinyl polymers rather than the older and better‐known condensation resins.
The Jigging of Modern Airframes
Authors: J.H.S.
Published: November 2014

THIS article is the first of a short series which is intended to summarize and, to some extent, correlate the methods used in the production of several well‐known types of modern aeroplanes. Particular attention will be paid to the methods of the Germans, not in order to publicize them (which they are more than able to do for themselves), but in order that all that is of merit may be gleaned from their work.
Carburettor Tuning and Testing
Authors: Ramsay D.
Published: November 2014

WHEN designing a carburettor for a given engine two main factors must be taken into consideration—the pressure drop over the carburettor and the metering characteristics. The pressure drop over the carburettor at full throttle causes a loss in available engine power; and in order to reduce this to a minimum the carburettor should be as large as possible consistent with reasonable mechanical size. The metering characteristics are, however, generally improved by using a small choke, and a compromise must be made between choke size and metering characteristics.
The Spot Welding of Light Alloys
Authors: Field Gordon H. , Sutton H.
Published: November 2014

The following items were examined:
Torsion in Rectangular Channels
Authors: Kittelsen H.J.M.
Published: November 2014

This article is intended, firstly, as a means to a quick determination of the maximum stresses in such a channel, and secondly, to give the reader a clearer insight into the behaviour of an open section generally.
Flutter at Altitude
Authors: Shipp J.C.K.
Published: November 2014

IN the 1940 Wilbur Wright memorial lecture on the future of British Civil Aviation Dr. Roxbec Cox has stated that the study of passenger convenience leads to consideration of over weather flying and that the study of improvements in safety leads to consideration of flutter prevention. He has stated also that all aviation authorities recognize the danger of flutter and warns that the chief danger to be guarded against in the future is a sense of security. It has, therefore, been thought worth while to examine the effect on wing flutter speed of flying at great heights. The effects have already been briefly considered by Williams, Pugsley and Duncan in this country and by Kassner and Fingado in Germany.
Glider Performance Calculation
Authors: Turner Keith W.
Published: November 2014

THE glider presents a simpler problem to the performance calculator than does the engine‐driven aeroplane: a problem free from the variables that are inevitably introduced when propulsion is derived from a complicated system of engine and airscrew. Nevertheless, the process of determining the performance to be expected of any projected glider design is usually quite a lengthy one; and if, in addition, an investigation is to be made into the effects of varying all the factors concerned, with a view to finding their optimum values, the process becomes so lengthy that in practice it is sometimes neglected. Glider development then tends to proceed along what may be described as Darwinian lines, and progress becomes unnecessarily slow: the evolution of gliders to fit new operational requirements as they arise takes longer than it need.
Notes on Enemy Bombsights
Authors: Postlethwaite F.
Published: November 2014

TESTS on modern aircraft have shown that a small advantage is to be gained by the use of pendulum stabilization over the spirit level, but it is hardly considered sufficient to warrant the additional complexity of mechanism involved, particularly when it is effected in the clumsy manner of this design. The pendulum and sighting assemblies weighs 20 lb., and the base and supporting arm 14 lb. in all a total of 34 lb.
Lagrangian Frequency Equations
Authors: Morris J. , Head J.W.
Published: November 2014

IN recent years much attention has been devoted to devising methods for the numerical solution of Lagrangian frequency equations in practical problems. A powerful method based on iteration was given by Duncan and Collar in the Phil. Mag. for May, 1934. This method, which was described by one of the present authors in AIRCRAFT ENGINEERING, Vol. XIV, April, 1942, pp. 108–110, is essentially one of successive approximation and lias the advantage of simultancously giving the modes associated with the frequencies. First the highest root is found together with its associated modes. Then by an ingenious artifice the equations are reduced by one degree being freed from the root found ; and so on. A defect of the method is due to the fact that the accuracy diminishes with each successive root. Consequently it becomes necessary to start the computation with a large number of significant figures in order to achieve the requisite accuracy as the number of roots to be found increases. There is another drawback to the method in that it cannot be applied to the general Lagrangian equations direct. They have first to be recast into “ canonical ” form in which the root to be found appears only along the “ leading diagonal”. This involves solutions of simultaneous equations with the same number of variables as the number of roots in the original equations.
Air‐line Engineering Management
Authors: Lusty Ivor
Published: November 2014

IV. SCHEDULING IT has been illustrated in Section III that over‐suitability in the engineering department is an inevitability if efficient working of an airline is sought after, for the cost of a certain degree of over‐suitability can be more than offset by the corresponding gain from improved flying operations. But even so, this over‐suitability is still a liability, so if means arc available to reduce the cost, these should be explored and exploited.
Air‐line Engineering Management
Authors: Lusty Ivor
Published: November 2014

VII.—MORALE WHEN an undertaking is nationally sponsored and, in part or in whole, Government financed; and when competition between itself and similar undertakings is non‐existent or remote, an atmosphere of security tends to creep in. In all except the most forceful personalities such security is apt to breed complacency.
Engine Crankshaft Frequency Curves
Authors: Morris J. , Evans W.J.
Published: November 2014

OWING to vibration troubles which occasionally arise in engine crankshaft propeller systems, it has become necessary to investigate such possibilities in the design stage. In this paper we are concerned with the torsional vibration of an engine crankshaft coupled with flexural vibration of the propeller. The engine crankshaft will have a number of throws, which it has become customary to replace by “equivalent” pulleys which have the same moments of inertia as the complete crankthrows and are usually designated as engine “masses”. Assuming that there is a node in the propeller shaft, we may represent the torsional stiffness of the propeller shaft between the gears and the node by ca / (l−γ) where ca is the torsional stiffness of the propeller shaft; the torsional stiffness of the other portion of the propeller shaft will then be ca/γ. The frequencies of torsional vibrations of the engine crankshaft system about the assumed node are found for various values of γ. The corresponding frequencies of flexural vibrations of the propeller arc also found for the same values of γ. The two sets of frequencies may then be plotted against γ, giving engine crankshaft and propeller frequency curves respectively.
Calculation of Wing Profile Drag
Authors: Holt Maurice
Published: November 2014

IN the March issue of AIRCRAFT ENGINEERING Mr. Falkner establishes a new power index law for the skin friction coefficient of a flat plate with fully turbulent boundary layer.
Airscrew Blade Twist Effects
Authors: Lockwood Taylor J.
Published: November 2014

ORDINARILY, for the purpose of strength calculations, as well as in estimating bending and torsional rigidity with a view to deriving blade deflections and investigating flutter characteristics, the blade is regarded as flat (i.e. as if designed for zero pitch); any effects of the twisted form of the blade in causing departures from the classical bending and torsion theories being regarded as secondary. It has never, however, been proved that they are actually negligible, and an approximate analysis indicates that they may in some cases become appreciable.
Solution of Biquadratic Equations
Authors: Brown W.S.
Published: November 2014

IN applications of mathematics to aerodynamics, the biquadratic or quartic equation is of frequentoccurrence.Itarises forinstance in studies of aircraft stability as the characteristic equation which determines the frequencies and dampings of the lateral, or, alternatively, the longitudinal modes of motion of an aircraft with fixed controls, following a disturbance from steady flight; and in other cases, as, for example, in the study of the stability of an aircraft with free controls or of a towed glider, it may occur in the course of the solution of an equation of higher order.
Strain‐Gauge Rosette Formulae
Authors: King J.C.
Published: November 2014

DURING recent years strain gauges have been used more and more in the aircraft industry as a means of assessing the loads in aircraft structures, both in structural testing laboratories and in flight. This increased use can be mainly attributed to the satisfactory development of successful electrical strain gauges of the resistance type and to the demand by engineers for a more complete knowledge of the load distribution in modern aircraft structures. Electrical strain gauges, although requiring accurate apparatus and a large amount of electrical wiring in addition, are much more easily attached to the structure than mechanical gauges and have the great advantage that they can be mounted in positions inaccessible to most mechanical gauges. This increased use of such gauges has been applied to the determination of the loads in tubes under combined bending and direct loading and to obtaining the direct and shear stresses in sheets and panels. The results of all this has been that more engineers have had reason to use the basic formulae for determining these quantities from the measured strains on three or more gauge lines.
Vibrations in Aircraft
Authors: Manley R.G.
Published: November 2014

THE present series of articles is intended to cover in a general manner the whole subject of vibration in aircraft. The study of aircraft vibration is a specialized branch of engineering science, calling for considerable practical skill and experience in the design and use of measuring equipment, as well as the ability to carry out the mathematical analyses which render test results intelligible and lead to the successful solution of vibration problems. The leading features of all mechanical vibration problems are, however, of such a nature as to be readily understood, and the aim of this series is to describe these leading features so as to facilitate the appreciation of the broad principles governing the avoidance of unpleasant or dangerous vibrations.
The Elasticity of Plywood
Authors: Roberts H.
Published: November 2014

THE increase in speeds of modern aircraft types has brought with it many stiffness criteria for the prevention of flutter, entailing an accurate estimate of the stiffness and rigidity of structural parts, and if the skinning of such plywood stressed skin units as fuselages, wings, and control surfaces is to be of reasonable weight, and the relevant Air Ministry requirements are to be simultaneously satisfied, it becomes essential that more rigid methods of stiffness estimations of plywood panels should be employed than has been done hitherto. The difficulties in getting theory and practice to agree are many and may be enumerated as follows:
The Conversion of Hardness Values
Authors: Skerry E.
Published: November 2014

THE employment of so many types of hardness testing machines, each designed with the object of meeting special requirements, has without doubt given rise to much misunderstanding and some confusion. In order to reach some common understanding of hardness values it has been the practice to prepare tables or curves or provide factors, so that values obtained by one of the various hardness testing methods may be converted to another, or to the generally accepted Brinell value.
Vibrations in Aircraft
Authors: Manley R.G.
Published: November 2014

THE majority of troublesome vibrations in aircraft arc forced vibrations, due to periodically varying forces originating in or around the power plant; the only important type which is not due to such a cause is flutter. Flutter is a vibration in a part of the aircraft structure set‐up by turbulence in the slipstream passing over the part, and has been the subject of a good deal of investigation from the early days of flying up to the present time. Control surfaces appear to be particularly susceptible to flutter, but a really spectacular example of mechanical failure from this cause is to be found in another branch of engineering—the failure of the Tacoma Bridge in America. In this case a suspension bridge, with a half‐mile central span, was completely wrecked by the effects of turbulent flow. The methods whereby aircraft designers avoid.the occurrence of similar failures are too specialized and intricate to be considered in this elementary study, and the reader is referred to the many reports on flutter included in the Air Ministry publication list.
Vibration of a Truncated Wedge
Authors: Conn J.F.C.
Published: November 2014

THE modes of vibration of a truncated wedge (i.e. a cantilever of rectangular plan form and linear thickness distribution, encastrd at the thicker end) have been investigated. Each mode of vibration is considered independently and solutions are obtained for the differential equations of motion, whence follow expressions for the natural frequencies of vibration. The particular case of the knife‐edged wedge is treated in some detail. The effects of damping and of rotatory inertia in flexural vibration are ignored and the solution for torsional vibration is valid only in those cases where the cross‐sections are relatively thin in comparison with the width. The results are of some practical utility in estimating the vibration frequencies of screw propeller blades.
The Aeronautical Museum
Authors: Davy M.J.B.
Published: November 2014

THE tree of exact knowledge of Science and Technology is now so great that the whole growth is beyond the practical compass of a single museum; the branches, while interrelated through the central stem, are very numerous and the knowledge increasingly diverse in application, so that some differentiation is necessary for profitable study. This is particularly the case in subjects where the application and usage of the knowledge has wide social implications, such as in aeronautics. It is idle to consider human flight apart from the uses to which it may be put and its potential value; to appreciate the full significance of flight it is necessary not only to understand the technical basis of aircraft, but also the vicissitudes of human progress whereby the machine came to be invented and highly developed. For this reason, the treatment of aeronautics in a museum should go beyond the treatment accorded to some other branches of science and technology.
Testing Lubricants and Bearing Materials
Authors: Brix V.H.
Published: November 2014

THE mechanical testing of engineering materials, such as tensile testing, hardness measurements, etc., has already attained a reasonable degree of standardization. The results of such tests can be expressed numerically and they furnish to a great extent adequate data to the designer who wishes to use them. Lubrication and bearing practice, however, has hardly emerged from the cradle of empiricism. Theory has had, as yet, but slight influence in developing reasonable design data and there still remains a wide field of research before the results can be expressed in such a simple tangible way as to transform efficient bearing design into mere slide rule manipulation. Precedent, past experience and a few odd rules are normally the designer's only guide and expensive practical experience his only check.
Redundant Pin‐Jointed Frames
Authors: Vincent H.E.
Published: November 2014

THERE is an old saying that before you can cook your hare you must first catch it. The stressman might interpret this as “before you can stress a redundant frame you must first find the redundancy”.
Production Control: Scheduling
Authors: Tiranti D.
Published: November 2014

IN our series of papers on Production Control in Aircraft Engineering, we have so far covered the following subjects: (1) Preproduction Planning (Dec. 1942), (2) The Production Plan (July 1944), (3) Shop‐loading (Aug. 1943), (4) Manufacturing Order Control (Jan. 1944), (5) A System of Works Control (September 1943). The British Standards Institution in their booklet 1100, Part I, Principles of Production Control, give 6 subjects as covering the entire field, (1) Scheduling, (2) Machine and Labour Utilization, (3) Stock Control, (4) Manufacturing Order Control, (5) Progressing, and (6) The Production Plan. It will therefore be seen that No. 1, Scheduling; No. 3, Stock Control; No. 5, Progressing, have not been covered. (Note: At this stage, we can assume that No. 2, Machine and Labour Utilization, was sufficiently dealt with in the Shop‐loading paper.)
Automatic Air Navigation
Authors: Scrimshaw F.H. , Wells J.A.
Published: November 2014

THE basic method of air navigation is deduced reckoning or simply dead reckoning. The method comprises the maintenance of an air pilot, which is made by calculating true airspeed and hence air distance run and then plotting this along the aircraft's heading from some initial ground fix. Subsequent ground positions may then be deduced by laying off the wind vector from the air position. As an example (Fig. 1) suppose an aircraft flics for one hour on a true heading of 060 deg. starting from an initial ground position A. If the true airspeed is 180 knots the air position will be at B, and if the mean wind over the flight is 45 knots from 340 deg. true then the ground position (by D.R.) corresponding to an air position at B would be at C. Now if the aircraft flics for the next hour on a true heading of 085 deg. and the mean wind over this hour is 30 knots from 310 deg. true, the air position with respect to A would be at D and the ground position at F. If a new air plot had been started at C then the air position, at the end of the second hour, would be at E and the ground position (by D.R.) again at F.
Assessing Control Qualities
Authors: Hick W.E.
Published: November 2014

IN so far as the behaviour of an aeroplane in flight depends upon the behaviour of its pilot, it is relatively unpredictable, and for practical purposes seems likely to remain so, except from a statistical point of view. It is, however, reasonable to suppose that by making certain simplifying assumptions it will be feasable to regard the pilot as a machine which responds to given situations in definite ways; in other words, to regard him as a form of servo mechanism with characteristics which may be adjusted to fit the average behaviour, though necessarily differing more or less from that of any given individual.
Wing Pitching Moment Coefficient
Authors: Morse W.L.
Published: November 2014

SCHRENK'S method for finding the wing lift distribution which has already been given in AIRCRAFT ENGINEERING can be taken further in order to determine the Pitching Moment Coefficient, CM0, about the quarter‐chord point of the mean chord at no‐lift.
Tailless Aeroplane Control Systems
Authors: Weyl A.R.
Published: November 2014

IN the tailless aeroplane, side‐slip motions during take‐off and landing manoeuvres are specially undesirable, since it tends to be deficient in lateral stability, as we have seen. Hence, arrangements which provide for early compensation of unintentional side‐slipping may have some justification.
High‐Lift Devices and Tailless Aeroplanes
Authors: Weyl A.R.
Published: November 2014

THE present conception of the air flow over aeroplane wings assumes that, in general, the flow pattern conforms closely to that of potential flow (i.e. the inviscid, incompressible flow of hydrodynamic theory) with the exception of a very thin layer of air which is in contact with the wing surface. This layer of fluid, the boundary layer, is characterized by the fact that all phenomena of viscosity (shear forces within the fluid) are restricted to it. Further, it is established that the lift is generated by a circulation about the aerofoil, and that stalling is a result of separation of the boundary layer from the wing surface at or near to the leading edge, with resulting vorticity over the dorsal wing surface, instead of an ordered flow with circulation. Thus at the stall, the circulation suffers a more or less complete breakdown.
Design and Production Technique
Authors: Schroeder A.J.
Published: November 2014

DRAWING technique comprises the methods of working in which hollow components are formed from plane material by means of a drawing die ring and a drawing punch and, if necessary, by using blank holders so that a more or less considerable movement of material takes place.
Pressure Air Cooling Technique
Authors: Lind Walker G.E.
Published: November 2014

THE combined effect of Sections III and IV is a gain of up to 3 per cent t.h.p. at moderate speeds, over the best systems without a blower, in spite of the detrimental effect of heating of the air due to compression. The blower absorbs about 10 per cent b.h.p. which is additionally recovered as useful thrust. Pressure air cooling does not permit the economical use of materially smaller matrices.
The DFS Reiher Sailplane
Authors: Shenstone B.S.
Published: November 2014

BECAUSE soaring flight is a peacetime pursuit, sailplane development since 1939 has been negligible. Effort has necessarily been diverted into the design of large military gliders having no soaring ability. With so many out of touch for so long, it may be worth while to look back a little and examine the best of the immediate pre‐war period.
Stress Diffusion Problems
Authors: Goodey W.J.
Published: November 2014

ACCORDING to Saint‐Venant's Principle, the distribution of stress in a body at points remote from the region of application of the applied loads is independent of the mode of application of these loads, being dependent only on their resultant (REF. 1).
Torsion in Conical and Cylindrical Shells Intersected by Planes
Authors: David F.W.
Published: November 2014

STIFFENED conical and cylindrical shells discontinued by plane intersections not parallel to the plane of the applied torsional moment are quite frequently encountered in aircraft design. For example: cockpit enclosure trays and floors in fuselages, sloping frames and spars in wings, etc.
The Evolution of Energy in Jet and Rocket Propulsion
Authors: Bielkowicz P.
Published: November 2014

IT is now possible to determine the temperature in the combustion chamber with greater accuracy than in Part V. However, to simplify the problem it is necessary to make a number of far‐going assumptions. A more detailed survey of phenomena occurring in the combustion chamber will be given in a later Part; at present we are merely enumerating the simplified schemes, which enable us to tackle the problem.
Stress Diffusion Problems
Authors: Goodey W.J.
Published: November 2014

IN this section we investigate various accurate solutions of the problem of the reinforced panel by using the stress‐function. We are then able to form an idea of the accuracy of the “stringer‐sheet” solution and of the conditions which must be satisfied in order that it may be reasonably accurate for practical purposes.
A Buckling Problem
Authors: Ratzersdorfer J.
Published: November 2014

IF a beam is laterally resting on a continuous elastic foundation then it is usually assumed in the technical literature that the intensity of lateral pressure p(u) is proportional to the deflexion v(u)
Graphical Method of Determining the Deflexion of Laterally Loaded Struts
Authors: Townsend N.A.
Published: November 2014

THE solution of the differential equations for the varied cases of laterally loaded struts present arithmetical difficulties particularly as the number of the integration constants contained in a problem increase. The time taken to obtain an acceptable solution can be extremely long if the first answer arrived at does not seem to be of the right order, thereby indicating an error in the evaluation of the constants.
The Stresses in Cylindrical Vessels
Authors: Conway H.D.
Published: November 2014

USING the general theory of cylindrical shells, expressions have been derived for the maximum bending moment and shearing force in vessels closed at one end and subjected internally to (a) gas pressure, (b) hydrostatic pressure. The method has been used by S. Timoshenko (Theory of Plates and Shells, McGraw‐Hill, pp. 412–3) for the special case where one end of the vessels is built into a rigid foundation.
The Bending Strength of Materials with a Non‐Linear Stress‐Strain Curve
Authors: Gill S.S.
Published: November 2014

THE article derives expressions for the position of the neutral axis and the failing moment of resistance of symmetrical and unsymmetrical I‐sections and channel sections, angles, solid circular sections and thick and thin tubes for materials for which the stress‐strain curve is non‐linear and is different in tension and compression.
Control in Flight Under Asymmetric Power
Authors: Yates A.H.
Published: November 2014

THE problem of designing an aircraft so that the pilot is able easily to regain and maintain control following the sudden failure of an engine has been for some years a serious one. It is thought that an elementary description of the aerodynamics of the problem and of the flight tests which are made to assess a particular aircraft may be of interest. The equally important problem of ensuring adequate performance after an engine failure is not discussed here.
Some Elementary Considerations of the Stress‐Strain Curve
Authors: Howarth R.M.
Published: November 2014

GREAT progress has been made in recent years in both fields of aircraft design and manufacture. No longer is the designer completely in the dark regarding the operational loads his aircraft will have to sustain, nor completely ignorant of the capabilities of its structure. Progress has brought knowledge of the sort of operational load likely to be encountered in both flight and landing operations as well as powerful methods of analysis of aircraft structures. Even that, however, is not enough, for without a thorough understanding of the possibilities and properties of the materials at the designer's command, he cannot hope to utilize such knowledge to the full.
Spring Tabs
Authors: Baker F.B.
Published: November 2014

The Effect of the C3 Term. The basic equation
Turning Errors of a Monitored Directional Gyroscope
Authors: Price H.L.
Published: November 2014

A General Statement of the Nature and Magnitude During the Course of, and Immediately after Recovery from, a True Banked Horizontal Turn and the Influence of Residual Compass Error on the A.P.I.
The Aviation Psychologist
Authors: Williams J.A.C.
Published: November 2014

AERONAUTICAL psychology has been haphazardly applied in the past, but the increased complexity of modern aircraft demands a scientific approach to the problems. Psychiatrists are mainly concerned with curing abnormal conditions of patients and are mostly drawn from the medical profession, but the psychologist has to apply his specialized knowledge to the normal person who is living and working under a given set of conditions whether it be piloting an aircraft or riveting the skin of the Brabazon I. Indeed, the person inserting rivets may have been ‘studied’ by a time and motion engineer who is in fact applying a part of the technique of the psychologist. Wherever the human being has to operate mechanical equipment there is scope for the psychologist to contribute towards increased efficiency.
Harmonic and Step Response of Simple Networks
Authors: Manley R.G.
Published: November 2014

NETWORKS of the type considered are of practical importance as components of automatic control systems and similar devices. The electrical variety is exemplified by the well‐known ‘phase‐advance’ network, while analogous arrangements of dashpots and springs arc often used to obtain the same effect.
Interference between a Tug and a Glider
Authors: Huls L.L. Th.
Published: November 2014

WHEN considering the dynamics of a combination of a tug and a glider one is apt to neglect the interference effects between the two aircraft, especially when the towing cable has a length of several hundred feet. That the disturbances caused by the tug have an appreciable influence on the forces acting on the glider was demonstrated by the results of flight tests recently carried out by the Nationaal Luchtvaartlaboratorium (National Aeronautical Research Institute), Amsterdam, Holland.
The Bending of Fuselage Shells
Authors: Taylor J.S. , Harper R.D.M.
Published: November 2014

THE paper suggests a new approach to the calculation of the bending strength of semi‐monocoque (and possibly fully mono‐coque) aircraft fuselage shells. The method described uses directly load‐deflexion graphs obtained from laboratory compression tests on panels representative of the shell at the section under consideration, and is analogous to the calculation of the form factor for a solid beam section, which factor is dependent on the shape of the section and on the stress‐strain relationship of the material of which the beam is made.
The Behaviour of Metals Under Multiaxial Stress Systems
Authors: Johnson A.E.
Published: November 2014

A SURVEY has been made of some aspects of behaviour of metals under multiaxial stress systems, taking into consideration available experimental evidence.
The Static Notch‐Bar Tensile Test
Authors: Fitzgerald‐Lee G.
Published: November 2014

VARIOUS steels, or even different heats of the same steel, with identical mechanical properties when determined by ordinary tests, vary considerably in behaviour in service; and such differences of performance are neither due to any variation in composition nor to any other known factors. That these differences exist is now known but their causes are still very much matters for metallurgical conjecture. It is known that steels tempered from the austenitic range and tempered to give a martensitic structure become increasingly ductile with rise of temperature. The ordinary tests, however, fail to give any indication of the variations in behaviour, on tempering, between even different low‐alloy steels, to say nothing of different heats of any one particular steel. The notched‐bar impact‐bend test is capable of revealing differences in impact properties among steels which have been tempered to levels of mechanical strength identical with the results obtained by ordinary tensile tests. The notched‐bar test is, however, highly complex, involving a certain amount of tension, compression, bending and shear, and its full significance is not yet clearly understood. Of its three characteristic features: high speed, notch, and bend action, the notch is the most potent embrittling factor. Recent investigations have shown that static notched‐bar tensile tests give more fully understandable results and evaluate metals in very much the same manner as impact tests.
The Fire Danger in Aircraft
Authors: Selby‐Hele R.H.
Published: November 2014

SO much good work has been done by the Airworthiness Authorities who, as a group, are the principal signatories to ICAO, that in certain transport category aircraft of recent vintage the chances are now reasonably remote of a fire occurring in flight, while the prospects of extinguishing it are roughly in inverse ratio to the chance of it occurring. Unfortunately, owing to the fact that relevant regulations are not always retroactive and in agreement, there are still far too few of these low fire‐risk aircraft.
The Rapid Solution of Cubic Equations
Authors: Hadekef R.
Published: November 2014

THE problem of finding approximate solutions of algebraic equations arises frequently in engineering practice; perhaps the most important or frequent instance is that of the ‘characteristic equation’ of a linear differential equation describing the behaviour of some electrical or mechanical system.
Manoeuvrability at High Speeds
Authors: Yates A.H.
Published: November 2014

FORTY years ago the pilots of the earliest aeroplanes were embarrassed by the very restricted speed range of their aircraft. Often the maximum level speed obtainable was a mere ten miles per hour above the stalling speed. As the art progressed the aerodynamicist and the power plant designer joined forces to raise the top speed while the invention of flaps and slots helped to offset the effects of increasing wing loading and kept the stalling speed to a reasonable value. For many years our pilots have enjoyed a comfortable speed range of several hundreds of miles per hour which even the increased stalling speed in steep turns has not seriously reduced. In the last few years, however, the pilots of the latest high speed, high flying fighters and bombers are worried by finding that the speed range of their aircraft is again becoming constrained, not only by the familiar boundaries of the stall and the maximum available speed, but by new and more fearful boundaries. What is the cause of the return of this aeronautical claustrophobia?
Some Notes on Centrifugal Compressors
Authors: Thompson L.N.
Published: November 2014

CENTRIFUGAL compressors have found their main use to date in jet engines—for example, all the early Whittle engines and many subsequent machines were fitted with this type. This was initially due to the fact that when aircraft gas turbines were first being considered seriously considerable experience had already been gained in the design and use of centrifugal superchargers for piston‐type aircraft engines. The similarity between the two types of machine therefore led to the adoption of centrifugals in the initial development stages of the gas turbine.
Manoeuvre Point Properties of the Aero‐Isodinic Wing
Authors: Taylor A.S.
Published: November 2014

As part of the R.A.E.‘s critical study of the aero‐isoclinic principle of wing design, a detailed examination was made of high‐speed aeroelastic effects on manoeuvre point, with special reference to the effect of rearward movement of local aerodynamic centres at super‐critical Mach numbers. From the results of calculations, using the method of R.A.E. Report No. Aero. 2320, it is concluded that as regards possible shifts of manoeuvre point, the aero‐isoclinic wing is generally superior to the conventional wing. For tailless aircraft, application of the aero‐isoclinic principle makes it possible to employ wings of an aspect ratio much larger than is considered practicable with conventional design. Structural design of a flutter‐free aero‐isoclinic wing entails radical departures from orthodox procedure, and with tailed aircraft it is therefore probably preferable to adapt the design of the tail plane and its attachment, to cope with the destabilizing deformability effects of a conventional wing, than to eradicate such effects at the source by aero‐isoclinic design of the wing.
Undercarriage Strength Testing from the Weight Aspect
Authors: Fisher W.T.
Published: November 2014

UNDERCARRIAGE design practice has been through several changes in the last few years; these have resulted in very much increased mechanical complication, fortunately accompanied by a decrease in weight, and it is interesting to consider the structural changes implied in these lower weights. (The trend is shown in FIG. 1 for airliner types; for some bomber aircraft it appears even more marked.)
Techniques of Flow Visualization
Authors: Balint E.
Published: November 2014

This article deals with the joint use of two branches of Physics for the solution of flow problems. These two branches arc Optics and Fluid Mechanics. The basic principles of Optics arc employed in the Fluid Mechanics Laboratory to provide insight into the flow of liquids and gases. Only techniques used in incompressible flow arc discussed: emphasis being laid on those useful in ‘free surface’ and ‘boundary’ type problems. Basic principles of similarity and optics are described and a brief appraisal of some of the methods is attempted, illustrated by experiments carried out in the Fluid Mechanics Laboratory of the Melbourne Technical College. Two techniques which are frequently used in problems of incompressible flow receive fairly detailed treatment; these are the fluid photo‐elastic apparatus and the smoke generator.
The Elementary Theory of Aero‐Elasticity
Authors: Broadbent E.G.
Published: November 2014

WE concluded Part II of this series with the remark that a different outlook is needed for problems of control surface flutter than for those of wing flutter. There are two reasons for this. Wing flutter must be investigated carefully early on in the design of an aircraft so as to provide a safe aircraft without a severe weight penalty, whereas the weight penalty of avoiding control surface flutter is usually small, although not negligible, and modifications can often be made at short notice, so it is important to make a full investigation as late as possible before flight when all the data are available in a reliable form. The second reason is that with wing flutter, as with aileron reversal and divergence, it is usual to think of safety margins in terms of forward speed or possibly wing torsional stiffness; with control surface flutter, on the other hand, quite different types of safety factor become the rule.
Thermal Problems of High Performance Flight
Authors: Rendel David
Published: November 2014

IN very high performance aircraft—that is aircraft flying at high speeds and high altitudes—the thermal problems confronting the mechanical engineer are becoming progressively more and more severe. Atmospheric Temperature ranges of upwards of 100 deg. C combined with thermodynamic effects due to the high speeds, widely varying air pressure and moisture content are encountered and very rigid temperature limits for the various component parts of the aircraft have to be met with equipment of a minimum size and weight and without materially affecting the overall performance of the machine.
Lift‐Curve Slope at Subsonic and Supersonic Speeds
Authors: Stanbrook A.
Published: November 2014

Theoretical results for the initial lift‐curve slope of straight‐tapered wings, based on the linearized equations of inviscid motion, have been evaluated and are presented in the form of graphs.