bluuebunny/crossref_metadata_2025 huggingface dataset:
The estimation of range of jet-propelled aircraft
Authors: Pearson H.
Published: July 2016

The statement that with modern aircraft and jet propulsion engines it is essential to match the engine and aircraft has become a platitude, without the reasons being quite so well appreciated. It is well known that should the aircraft be operating away from its “ design point,” involving throttling back of the engine, then the loss of efficiency with either jet or turbine airscrew engines is liable to be serious, and to have a large effect on the range. There is also a firm conviction that very high altitude is necessary in order to give a jet aircraft any range worth mentioning.

It seems worth while to examine in a simple way on what qualities of the engine the range depends. The object of this simplified attack on the problem is two-fold; first of all it enables the factors to be readily appreciated, and second it provides rapid methods of comparing the qualities of two different engine types for range.
On non-steady motion of slender bodies
Authors: Miles John W.
Published: July 2016

Following the original work of Munk, Jones, and Ward for steady flow, a solution is given for unsteady, supersonic flow over very slender bodies of revolution and wings. The results are subject to the restriction (M2- l)δ2loge[(M2- 1)½δ]«1 where δ is the slenderness ratio,Mis the Mach number and, in addition, to the usual restrictions imposed by linearisation. As examples, the lifts and pitching moments on flat wings and bodies of revolution executing pitching motion and the damping moment on a rolling wing are calculated.

It is shown that the order of approximation is consistent with the limitations already imposed by linearisation, at least in supersonic flow, where no Kutta condition is required.
Some developments of expansion methods for solving the flutter equations
Authors: Williams John
Published: July 2016

In a theoretical flutter analysis, the real zeros x˂0,y˃0, of a stability determinant Δ(√x, y) which is a polynomial in y are required, and can readily be evaluated once the polynomial expansions are known for assigned values of x. When the air loads are estimated on the basis of classical derivative theory, Δ becomes a bivariate polynomial in √x and y of a special type. Direct expansion of the stability determinant becomes too involved when the number of degrees of freedom is large and indirect methods of expansion are needed.

A method of bivariate expansion which uses a framework of lines subject to certain restrictions is examined in Part I, and is applied to a quaternary wing-flutter problem. The analysis shows that frameworks previously proposed, having all intersections outside the flutter quadrant (x˂0, y˃0), demand very high computational accuracy. A new framework is suggested having all intersections inside the flutter quadrant. The improvement in computational accuracy is considerable.
Supersonic flow investigations with a “hydraulic analogy” water channel
Authors: Black Joseph , Mediratta O. P.
Published: July 2016

Summmary

This paper describes the construction of a water channel in the University of Bristol for the investigation of the analogy between the two-dimensional flow of a gas and that of shallow water with a free surface. Both continuous and discontinuous flow were examined, with a view to determining the limitations of the analogy.

Continuous “ shooting “ water flow was found to be reasonably analogous with supersonic isentropic gas flow, a static depth of about half an inch appearing to be satisfactory with this particular channel. No independent check was made of the agreement, or otherwise, between “streaming” water flow and subsonic gas flow, since the method of checking used was the measurement of the angle of the waves formed on the water surface, and such waves exist only in “ shooting” flow.
Contracting ducts of finite length
Authors: Whitehead L. G. , Wu L. Y. , Waters M. H. L.
Published: July 2016

Summmary

A method of design is given for wind tunnel contractions for two-dimensional flow and for flow with axial symmetry. The two-dimensional designs are based on a boundary chosen in the hodograph plane for which the flow is found by the method of images. The three-dimensional method uses the velocity potential and the stream function of the two-dimensional flow as independent variables and the equation for the three-dimensional stream function is solved approximately. The accuracy of the approximate method is checked by comparison with a solution obtained by Southwell's relaxation method.

In both the two and the three-dimensional designs the curved wall is of finite length with parallel sections upstream and downstream. The effects of the parallel parts of the channel on the rise of pressure near the wall at the start of the contraction and on the velocity distribution across the working section can therefore be estimated.
The Symmetric Vibrations of Aircraft
Authors: Traill-Nash R. W.
Published: July 2016

The eigenvalue equations for symmetric vibration of a complete aircraft are derived in a very general form. The “lumped mass” approximation to the continuous mass distribution is used and sub-matrices are associated with properties of relatively simple branches of the system. The final eigenvalue equations are expressed in terms of these sub-matrices, so that in a numerical application the physical system, as such, is considered only in relation to the properties of the simple branches. It is assumed initially that the aircraft wing and tail have flexural axes of the conventional type, but it is shown in the Appendix that under certain conditions the treatment can be generalised to cover swept and cranked wing aircraft.
The Flow of an Incompressible Fluid through an Axial Turbo-Machine with any Number of Rows
Authors: Railly J. W.
Published: July 2016

A method is described whereby, at any point in an infinite parallel annulus, the approximate axial velocity due to a single row of high aspect ratio blades may be calculated from a knowledge of the conditions of flow adjacent to the blades. The method is based on the assumption of a simplified expression for the radial velocity, being the product of an unknown function of the radius and an exponential term independent of the radius containing an undetermined constant; the function and the undetermined constant are calculated by reference to the conditions of flow in the plane of the row considered. The flow due to any number of rows is then obtained by summing the radial velocity fields due to each row and obtaining the axial velocities by integration of the equation of continuity.

The solution of the problem with infinitely many rows is shown to have a simple form by virtue of the fact that the flow (provided that the velocities remain finite) settles down to a pattern which is periodic by one stage pitch.
A New Treatment of the Tuned Absorber with Damping
Authors: Johnson D.C.
Published: July 2016

The design of the damped tuned vibration absorber, which has previously been treated algebraically, is studied by the use of a three-dimensional admittance diagram. The advantages of this method are that the basic principles can be more easily understood and that it is not necessary to simplify the vibrating system so much. The results obtained by the use of the method show that under some conditions the algebraic treatment does not give the optimum tuning, but that the differences in performance of dampers which have been designed by the two methods will not be large. It is shown how the method may be extended to more complex problems.
The Sensitivity and Range Required in a Toepler Schlieren Apparatus for Photography of High-Speed Air Flow
Authors: Mair W. A.
Published: July 2016

A simple theoretical analysis is given of the quantities affecting the sensitivity and range of a schlieren apparatus. In regions of large density gradient the deflections of the light rays may lie outside the normal working range. When this occurs, dark regions may appear in parts of the photograph that would normally be light. Examples of this effect are given, and it is shown that confusion can be avoided by taking photographs in pairs, with the knife edges or slits arranged to give sensitivities of opposite sign.

The deflections of light rays in various typical disturbances in a supersonic air stream are calculated, using geometrical optics. Prandtl-Meyer expansions, boundary layers, and plane and curved shock waves are considered. From these calculated deflections it is shown that some of the anomalous effects commonly observed in schlieren photographs can be explained.
A Note on the Theory of the Constant-Area Mixing of Compressible Flows as Applied to High-Speed Wind Tunnel Design
Authors: Irving F. G.
Published: July 2016

The one-dimensional equations governing the mixing of compressible flows in a channel of constant cross-sectional area are derived and are used to investigate the running of an induction-type high-speed wind tunnel. While in practice it is usually difficult to achieve working section Mach numbers greater than about 1.8 to 20 in this type of tunnel, this simple theory gives no obvious reason for this and indicates that higher Mach numbers should be attainable.

It is also shown that an increase in efficiency is predicted, particularly at the higher supersonic Mach numbers, if the injected stream enters the mixing section at the same Mach number as that of the working section main stream.
The Flow Past Elliptic-nosed Cylinders and Bodies of Revolution in Supersonic Air Streams
Authors: Holder D. W. , Chinneck A.
Published: July 2016

The flow past families of two-dimensional cylinders and bodies of revolution with elliptic noses at zero incidence has been examined at free stream Mach numbers between 1·42 and 1·82. The observations include schlieren photographs and measurements of the pressure distributions at the surface.

The measured pressure distributions and positions of the detached bow waves are found to be in fair agreement with values calculated by a number of methods. The drag coefficients of the slender two-dimensional elliptic noses are considerably higher than those calculated for wedges of the same axis ratio with attached shock waves, but the drags become almost equal when the axis ratio approaches the value for subsonic flow behind the bow wave of the wedge. For most axis ratios the drag coefficients of the elliptic-nosed bodies of revolution are lower than those for cones of the same axis ratio.
The Second Order Terms in Two-Dimensional Tunnel Blockage
Authors: Woods L. C.
Published: July 2016

This paper gives a new calculation of the solid and wake blockage for compressible subsonic flow about a symmetrical two-dimensional aerofoil, midway between symmetrically disposed tunnel walls, which need not be straight. Previous calculations have been based on the theory of sources, and the results obtained have usually involved only first order terms. At high subsonic Mach numbers the second order terms become important; they are given in this paper. The theory is based on an integral equation, which is exact for incompressible flow, and which is more accurate than linear pertubation theory in compressible flow. The effect on blockage of a possible increase in the boundary layer displacement thickness on the tunnel wall, due to the presence of the aerofoil, is investigated, and finally a method of calculating the total blockage from wall pressure measurements is given.
Apparatus for the Remote Recording of Flow Conditions
Authors: Todd K. W.
Published: July 2016

An instrument is described which detects total pressure, total temperature, and direction of flow simultaneously in a stream tube of one-sixteenth inch diameter. The observed directions and pressures are transmitted electrically to a remote station where they appear as pencil traces on a paper record which moves at a rate proportional to the traverse rate of the instrument. The temperature is noted at intervals and added manually to the trace. Integrators are included which permit rapid assessment of mean pressure and direction at the conclusion of a traverse, the control and maintenance of setting of the instrument being semi-automatic. A further development is also noted whereby total pressure and direction in three dimensions can be observed either manually, or remotely, by automatic means.
The Compressible Flow Through Cascade Actuator Discs
Authors: Horlock J. H.
Published: July 2016

A theory of the incompressible flow through two- and three-dimensional cascade actuator discs has been developed by several workers over the past ten years, and its accuracy has been confirmed in several experiments. This theory is briefly reviewed, and a parallel theory for subsonic compressible flow through actuator discs is developed. Approximate solutions for several examples are considered, including a compressible shear flow through a two-dimensional cascade, and a compressible flow through an annular cascade of guide vanes.
The Relation between Zero Errors and Bandwidths for Different Types of Rate-of-Turn Meters
Authors: Sutcliffe H.
Published: July 2016

In a conventional rate-of-turn measuring gyroscope the necessity to use a displacement transducer results in an appreciable zero error when a rapid response is required. Other types of instrument, employing alternating forces and force transducers, are also shown to have a relation between error and response time. An assessment is made of these relations and conclusions are reached concerning the relative merits of the different types. The results are given in terms of the estimated rate errors as functions of bandwidth.
Combustion in Liquid-Fuel Rocket Motors
Authors: Spalding D. B.
Published: July 2016

The paper provides a simplified picture of the processes occurring in liquid bi-propellant rocket motors. Droplet vaporisation, chemical reaction, and drag between gas and droplet are considered for a one-dimensional model. Quantitative theoretical results are presented for the variation of droplet size, droplet velocity, gas temperature and gas velocity within the chamber, particular attention being paid to the calculation of L*. The theory is applied to the German V2 rocket motor. Practical conclusions from, and extensions to, the theory are discussed.
The Ground Effect on the Jet Flap in Two Dimensions
Authors: Huggett D. J.
Published: July 2016

The effect of the ground on a jet-flap aerofoil in two-dimensional flow is investigated, with particular reference to the conditions under which the jet flow hits the ground. Experimental results are included for the change of lift and pitching moment for 58·1° and 31·4° jet-deflection angles, with a limited investigation into the downwash changes behind the model with a 58·1° jet-deflection angle. It is concluded that there is a definite limit to the jet coefficient, which may be used at any ground position, if the problems of a sudden change of lift and pitching moment are to be avoided. There remains the unresolved difficulty of the downwash variation at the tail arising from the presence of the ground.

A provisional assessment of the performance of a jet-flap aircraft near the ground is made, and shows that for a 58·1° jet-deflection angle there is a definite limit to the minimum flying speed for any given distance of the wing from the ground.

The fact that there appears to be a maximum pressure lift coefficient, independent of the jet-deflection angle, which may be obtained at any ground position, is investigated. An attempt is made to provide a theoretical explanation of this on the basis of the critical condition of blockage underneath the aerofoil.
Thermal Stresses in Rectangular Plates
Authors: Przemieniecki J. S.
Published: July 2016

The characteristic functions for beam vibration modes are used to derive an approximate solution for the calculation of thermal stresses in rectangular isotropic flat plates subjected to arbitrary temperature distributions in the plane of the plate and constant temperatures through the plate thickness. The thermal stresses are obtained in the form of generalised Fourier expansions in terms of the characteristic functions, and their derivatives, representing normal modes of vibration of a clamped-clamped beam. Since these functions have recently been tabulated, the practical application of this new method to the thermoelastic stress analysis of plates presents no difficulty.
Supersonic Flow Past Slender Pointed Wings with “Similar” Cross Sections at Zero Lift
Authors: Lord W. T. , Brebner G. G.
Published: July 2016

Some recent theoretical work on slender pointed wings at zero lift is co-ordinated and extended. The wings considered may have any pointed plan form shape, provided that the trailing edge is straight and unswept. The root section profile and cross-section shapes are arbitrary, provided that, on any one wing, the latter are “descriptively similar” (diamond or parabolic biconvex for instance), though not necessarily geometrically similar. The chief aim of the work is to find wings with simple geometry, low wave drag and pressure distributions which are unlikely to be seriously affected by viscous effects. Wave drag and pressure distributions are calculated by slender-wing theory. General formulae, which are both simple and instructive, are given for the wave drag and the overall pressure distribution, with particular emphasis on the root pressure distribution. Results for a number of wings of special interest are presented and discussed.
Plasto-Elastic Stress Distributions in Lugs
Authors: Fessler H. , Haines D. J.
Published: July 2016

A photoelastic layer was bonded to the face of aluminium alloy lugs and the strain distribution in the lugs was determined from the photoelastic fringe patterns which were recorded in a reflection-type polariscope. The semicircularly- ended lugs were loaded through neat fitting hardened steel pins. Assuming the maximum shear stress criterion of yield, the region of yielding under different loads was determined from the fringe patterns. Yield contours are shown for each of the four ratios of (hole diameter)/(lug width) tested. The greatest shear strains in the lugs were related to the applied loads. The extent of yield across the section normal to the direction of loading was measured for different loads and it was found that the progress of yield across this section is independent of the (hole diameter)/(lug width) ratio. The residual stresses on this section were also estimated. Complete yielding across the lug was related to the properties of the material and to the fracture strength of the lugs. Local yielding due to surface irregularities remained local, showing that “bedding in” does not weaken the component under static loading conditions.
The Eftect of Jet Noise on Aircraft Structures
Authors: Clarkson B. L.
Published: July 2016

The present state of knowledge on the problem of fatigue failure due to vibrations excited by jet noise is reviewed. It is concluded that it should currently be possible to make reasonable estimates of the stress levels set up in a structure by jet noise but, in general, the resultant fatigue life of the components cannot be estimated with any confidence.
Flow in a Viscous Trailing Vortex
Authors: Newman B. G.
Published: July 2016

The equations of motion for an isolated laminar viscous vortex at moderate to large Reynolds numbers are linearised, by assuming that both the rotational velocity and the deficit of longitudinal velocity are small compared with that in the free stream. The rotational motion and the longitudinal motion may then be superimposed and solutions are readily obtained for each. If the vortex is generated by a body with profile drag it is predicted that the deficit of longitudinal velocity will be positive, which is in agreement with experimental observation. Further details of the solution and its relation to the flow in real vortices are discussed; and the theory is compared with some measurements in a turbulent vortex.
Asymmetrically Plate-Reinforced Circular Hole in a Uniformly End-Loaded Flat Plate
Authors: Hicks Raymond
Published: July 2016

General expressions are obtained for the stress distribution in a flat plate end-loaded by equal principal stresses and containing a circular hole reinforced by an annular plate. The reinforcement is placed on one side of the plate only so that the other side remains flush. It is shown that the effect of an asymmetrically placed reinforcement is to induce, in the plate and rein-forcement, bending stresses which are not negligible compared with the externally applied direct stress. From particular examples it is found that reinforcements having practical dimensions can give rise to stress concentrations in the same order of magnitude as those in a similarly loaded plate containing an unreinforced hole. For practical purposes, data have been obtained which enable the designer to determine quickly the stress distributions associated with reinforcements and plates having a reasonably wide range of dimensions.
The Atmospheric Stress-Corrosion Resistance of some Forged High Strength Aluminium Alloys and an Assessment of the Effects of a Step-Quench into Molten Salt
Authors: Doyle W. M. , Jones R. G.
Published: July 2016

Since the introduction of aluminium-zinc-magnesium-copper alloys, investigations into the behaviour of these high strength materials, over a wide range of composition, have indicated the significance of corrosion as a factor affecting the cracking of these alloys after prolonged stressing at loads below the ultimate tensile strength of the material.

Most of the previous work designed to assess the stress-corrosion resistance of aluminium-zinc-magnesium-copper alloys (D.T.D. 683A*) was carried out on sheet and plate material and the present investigation is concerned with the examination of these materials in the form of large hand-forged slabs, tested in the short transverse direction.
A Theory for Flow with Axial Symmetry in Centrifugal Impellers
Authors: Tonks R. J. , Smith A. G.
Published: July 2016

A theory of incompressible flow with axial symmetry through the impeller of a centrifugal compressor is given more fully and more accurately that by previous writers. The theory is applied to compute the flow through two different impellers. For each design the experimental axial velocity distribution at the impeller eye is in good agreement with that computed numerically from the theory. This means that for the impeller assembly—not untypical of modern designs—considered here, theoretical calculation of intake axial velocity should provide a useful guide to designers.
Heat and Mass Transfer in Aeronautical Engineering
Authors: Spalding D. B.
Published: July 2016

The main purpose of the paper is to show that standard techniques of heat and mass transfer theory, as practised in other branches of engineering, can be helpfully applied to the corresponding aeronautical problems, particularly those arising in connection with high-speed flight and rocket propulsion.
The Bending and Twisting of a Flat Elastic Plate with a Reinforced Circular Hole
Authors: Hicks R.
Published: July 2016

This paper considers the problem of a reinforced circular hole in a bent or twisted flat elastic plate having small deflections. The reinforcement is chosen so that the ratio of its radial width to the diameter of the hole is small; this implies that there is no radial stress variation across sections of the reinforcement. Using the classical theory for bending, expressions are obtained for the boundary conditions at the junction of the reinforcement and plate. The expressions are general in so far as they are also applicable to plates under the action of lateral loading. The following particular problems are considered: —(a) uniform bending about one or two axes, (b) uniform twisting about two axes. For the particular case of uniform bending about one axis, data has been obtained for the stress concentration around holes for plates and reinforcements having a reasonably wide range of practical dimensions.
Experimental Investigation of the Stalled Flow of a Single-Stage Axial Flow Compressor
Authors: Wood M. D. , Horlock J. H. , Armstrong E. K.
Published: July 2016

Experimentally it is shown that variation of axial spacing between
neighbouring blade rows can alter the stall characteristics of a compressor
stage. The stall cell patterns of this compressor stage are described in detail
and changes of slope in stage temperature and pressure rise characteristics are
explained in terms of stall propagation. Strain gauge tests on stator blades
are used to indicate the possibility of large dynamic stresses occurring when
the stall cell frequency is equal to the blade natural bending frequency.
Analysis of Stress Concentrations at Reinforced Holes in Infinite Sheets
Authors: Wittrick W. H.
Published: July 2016

Equations are derived which enable the stresses around a compactly reinforced hole in an infinite sheet to be computed. The only restrictions placed on the shape of the hole are that it has at least one axis of symmetry and that the region outside it can be conformally mapped on to the region outside the unit circle by a transformation function in the form of a polynomial of any order. This admits a very wide range of holes of practical importance, including circles, ellipses, and squares, triangles and rectangles with rounded corners. Two loading cases are treated; the first corresponds to uniform tensions at infinity in directions parallel and perpendicular to the axis of symmetry of the hole, and the second to uniform shear at infinity in these directions. Superposition of these basic loading cases enables the stresses to be determined for any uniform state of stress at infinity. The equations are in an ideal form for use with a digital computer.
Limitations of the Sonic Area Rule
Authors: Sheppard L. M.
Published: July 2016

Recent free flight tests have provided information on the applicability of the sonic area rule to non-lifting configurations. An analysis of results for the sonic wave drag of swept-back, tapered wings has suggested that the sonic area rule is applicable to thin wing and slender body combinations provided that the product of the wing span/length ratio and the cube root of the thickness /chord ratio is less than unity. The wing span/length ratio was found to be a much more useful slenderness parameter than the aspect ratio.

When the wing has a round-nosed section, theoretical considerations predict the existence of a so-called leading edge drag force varying with Mach number. One would expect such a wing to have the same sonic drag-rise as the equivalent body with an identical cross-sectional area distribution. Some test results do not confirm this drag-rise equivalence. It appears that the transonic drag-rise of the leading edge force is much greater than that predicted by theory.

Tests on one basic wing-body combination, with different body cross-sectional shapes of the same area, suggest that the cross-sectional shape, of a smooth slender body, has no influence on the transonic wave drag of a configuration.
Design Charts for Transient Temperature and Thermal Stress Distributions in Thermally Thick Plates
Authors: Przemieniecki J. S.
Published: July 2016

A set of design charts is presented for the calculation of transient temperature and thermal stress distributions in thermally thick plates subjected to aerodynamic heating.

The method is particularly useful for determining temperatures and thermal stresses in plates with an arbitrary variation of the heat transfer coefficient and the adiabatic wall temperature of the boundary layer. The present method is based on repetitive applications of the exact analytical solution to a unit triangular variation of the adiabatic wall temperature and a constant heat transfer coefficient. The actual variation of the adiabatic wall temperature is represented as a series of straight lines while the heat transfer coefficient is approximated by a step function. The temperature distribution through the plate is separated into linear and “self-equilibrating” temperature distributions to facilitate thermal stress calculations; these distributions can be obtained directly from the design charts presented in this paper.

The general principle of this semi-numerical method is also applied to thermally thin plates subjected to arbitrary heating conditions.
Boundary Layers over Infinite Yawed Wings
Authors: Cooke J. C.
Published: July 2016

A method of calculating turbulent boundary layers on infinite yawed wings is given, making use of a method of calculating turbulent boundary layers due to Spence and of an analogy between three-dimensional and axi-symmetric boundary layers. It is also shown that the displacement thickness is equal to that computed using chordwise components and that the streamwise momentum thickness is approximately equal to the chordwise momentum thickness. Shock-free flow and small boundary layer cross-flow are assumed.
The Aerodynamic Forces Associated with Harmonic Motion of Slender Wings on Stationary Bodies of Revolution
Authors: Milne R. D.
Published: July 2016

The slender-body theory is applied to the determination of the unsteady aerodynamic forces on slender wing-body combinations when the body is stationary and the wing is deforming harmonically. The uniform body is circular in cross section, the wings are placed symmetrically and the wing deformation mode is necessarily symmetrical about a vertical plane through the body axis. The frequency parameter is restricted to that range for which the “cross-flow” potential equation is Laplace's equation. The case of an allmoving slender control surface on a body is treated in detail and numerical results are given for the forces and moments on body and control surface when the control plan form is triangular: the presence of a gap is neglected.
The Quasi-Cylinder of Specified Thickness and Shell Loading in Supersonic Flow
Authors: Portnoy H.
Published: July 2016

The methods of the operational calculus are used to obtain a linear approximation to the shape of the mean camber surface of a quasi-cylinder in a supersonic flow in terms of its shell thickness and loading distributions. The analysis deals with a generalised quasi-cylinder; that is one which, although lying close to a mean cylinder, need not possess axial symmetry. The quasi-cylinder is also permitted to be within the small disturbance field of other separate components, e.g. a centre-body. Because the linearised theory is inadmissable for internal duct flows close to and beyond the first reflected characteristic cone, the present solution is likewise invalid close to and beyond the position where this characteristic meets the mean cylinder. The work given here enables the camber shapes of “ring-wings”, which have been used theoretically to reduce or even nullify the wave-drag of a central slender-body, to be found. An example illustrates the general method.
The Effect of Fuel Distribution on Reaction Rates
Authors: Herbert M. V.
Published: July 2016

Theoretical reaction rate considerations normally require homogeneity of the mixture supply. An attempt—necessarily crude by reason of the analytical difficulties—is made here to cater for the case of non-uniform fuel distribution. Assuming a point-source injector in a parallel pipe, the “loss” in reaction rate is calculated for a limited number of specimen cases.
Compression Tests on Thin-Walled Cylinders
Authors: Holmes M.
Published: July 2016

The paper describes compression tests on eight thin-walled cylinders of 3 ft. diameter and 0·035 in. wall thickness made of aluminium alloy plate. The lengths of the cylinders were either 6 ft. or 9 ft. Three of the cylinders were tested under axial compression up to buckling failure, and the initial buckling load, failing load and mode of buckling were observed. A further three cylinders were similarly tested, but these cylinders were subjected to internal pressure before applying the compressive load. The internal pressure had a twofold strengthening effect on these cylinders. Firstly, it induced a tensile pre-stress along the axis of the cylinder and, secondly, it resulted in the value of the compressive stress at which buckling occurred being greater than the buckling stress value for the unpressurised cylinders. The six cylinders were tested in a manner which allowed the end face of each cylinder to rotate about a diametral axis. A parallel platen device was used in testing the last two cylinders (in an unpressurised condition) which restrained rotation of the end faces of the cylinders. These tests enabled the effect of end restraint to be studied, and also enabled measurements of load-carrying capacity at large axial deflections to be made. The initial buckling loads, failing loads and modes of buckling observed in the tests were compared with existing large deflection theory.
Mass Transfer Cooling in a Boundary Layer
Authors: Hurley D. G.
Published: July 2016

Previous theoretical work on mass transfer cooling is reviewed and it is shown that this may be complemented by similar solutions that occur when the velocity outside a two-dimensional boundary layer varies as some power of the distance from the front stagnation point. The case of stagnation point flow with constant wall temperature is investigated in some detail, under the assumption that the temperature differences are everywhere small compared with the absolute temperature. Calculations on an analogue computer, supplemented by an investigation of the asymptotic behaviour, are used to determine the boundary layer development and heat transfer rates when the coolant is hydrogen, helium, steam or carbon dioxide. It is found that, on a mass flow basis, hydrogen reduces the heat transfer rate most and that steam is the next most effective of the substances investigated.
Lift/Drag Ratios of Optimised Slewed Elliptic Wings at Supersonic Speeds
Authors: Smith J.H.B.
Published: July 2016

Previous work by R. T. Jones on the drag minimisation of elliptic wings is extended to the case of the slewed wing with thickness. These results are used to calculate lift/drag ratios of idealised configurations related to a supersonic transport aircraft. The values of lift/drag ratio and optimum slenderness ratio found are comparable with those calculated earlier in studies of delta-like plan forms.
The Deformational Behaviour of Low Aspect Ratio Multi-Web Wings
Authors: H. Gallagher R. , Rattinger I.
Published: July 2016

Results of a study of the accuracy attainable from various approaches to low aspect ratio wing deformational analyses are described. Seven model multi-web wings, representing a restricted range of sweep angles, aspect ratios and other geometric factors, were tested for deflection influence coefficients. Methods of matrix structural analysis and other techniques, involving numerous idealisations, were then applied in the prediction of the test data. This paper presents the experimental data. Subsequent papers will describe the analytical methods, the level of test-theory correspondence, and the merits and shortcomings of the theories studied.
The Static Aeroelastic Deformation of Slender Configurations
Authors: Hancock G. J.
Published: July 2016

Calculations have been applied to a series of flexible plates (delta, gothic and ogee) to estimate their static aeroelastic behaviour. Assuming linear aerodynamics, the general tendencies of Part I are particularised. Assuming non-linear aerodynamics, it is shown that in general two positions of equilibrium are apparently possible at each speed. The stability of the models is not considered.
The Correlation of Unstable Crack Length Data for Sheet Materials
Authors: Welbourne E. R.
Published: July 2016

A semi-empirical analysis of unstable crack propagation in thin sheets is given. An effective value of the crack tip strain concentration factor is used as the criterion for instability. Good correlation is achieved with experimental results from unreinforced sheets of aluminium and titanium alloys and high-strength steels. The interdependence of geometry and stressstrain curve properties in determining the unstable crack propagation characteristics of sheet materials is illustrated in an appendix.
Shear Buckling of Clamped and Simply-Supported Infinitely Long Plates Reinforced by Transverse Stiffeners and a Central Longitudinal Stiffener
Authors: Rockey K. C. , Cook I. T.
Published: July 2016

The paper presents a solution to the buckling under shear stress of infinitely long plates which are reinforced by both transverse stiffeners and longitudinal stiffeners. Each family of stiffeners is assumed to consist of equally spaced stiffeners. Both simply-supported and clamped edge conditions are examined. Numerical results are obtained for the case of a plate with transverse stiffeners and a central longitudinal stiffener and relationships between the buckling stress and the flexural rigidity parameters of the stiffeners are provided for three different spacings of the transverse stiffeners.
Effects of External Heat Addition on Supersonic Cruise Performance
Authors: Townend L. H.
Published: July 2016

Heat addition in the external flow around a supersonic aircraft may produce a field of increased pressure and thereby a propulsive and a lifting force. Less specifically, such effects could be produced by alternative processes involving the gradual expenditure of energy stored in an aircraft, and, according to the process, could be available at hyper-, super-, or subsonic speeds. A generalised study is made of associated effects on cruising range. Results are presented as performance “frameworks,” within which future experimental or analytic data should define regions of feasibility for particular systems.
Stress Concentrations for a Family of Uniformly Reinforced Square Holes with Rounded Corners
Authors: Wittrick W. H.
Published: July 2016

The stress concentration factors for a family of square holes, with varying degrees of curvature at the corners, and with varying amounts of compact uniform reinforcement on the boundary, have been computed for each of four loading cases. Poisson's ratio was assumed to be 1/3.
An Approximate Theoretical Approach for the Determination of Oscillatory Aerodynamic Coefficients for a Helicopter Rotor in Forward Flight
Authors: Molyneux W. G.
Published: July 2016

A method is described for the determination of the oscillatory aerodynamic coefficients for a helicopter rotor in forward flight. The method treats the blades and the recirculating wakes on a three-dimensional basis, but certain approximations are made so that the problem is tractable. In particular it is assumed that the downwash effect of a wake sheet beneath the rotor can be represented by concentrating the doublet distribution in the sheet in a single line of doublets.
Fatigue of Unmachined Aluminium Alloy Extrusions
Authors: Gunn K. W. , Woodward A. R.
Published: July 2016

The fatigue properties of unmachined extrusions of high-strength aluminium-copper alloys are known to be lower than those of conventional fully-machined test pieces. Work described in this note has shown that the removal of a layer of metal 0·025 in. thick from the surface of B.S. L65-type extrusions results in an increase in fatigue properties to values approaching those obtained from the conventional laboratory test pieces. Because the removal of material from the surface is not always a practical proposition, other methods of improving strength have been examined and the effect of surface compressive stresses has been shown to be beneficial. Sufficient compressive stress can be induced by surface-rolling to increase the fatigue properties to those of conventional specimens, but this method can only be easily applied to round sections and it is suggested that shot-peening or vapour-blasting could be used for more complicated sections.
Impact Theory Calculations of the Lift and Drag of Ducted Bodies
Authors: Tinkler J.
Published: July 2016

Newtonian impact theory has been used to estimate the external pressure forces on ducted bodies of rectangular, circular and semi-circular cross section. With an allowance for skin friction (or other incidence-independent drag) it is shown that maximum lift/drag ratios of about three to four are possible with little effect of body geometry provided that short and very divergent, or tall and narrow rectangular ducts are avoided.

Large changes occur in the separate lift and drag at maximum lift/drag ratio and these have to be made compatible with the weight and thrust capacity of the configurations. The maximum lift/drag ratio of a duct can be improved by the addition of wings, especially for a duct with poor lift/drag ratio, but the best overall performance is with a duct of good lift/drag ratio and low drag.

It is anticipated that impact theory underestimates the pressure forces, and hence the lift/drag ratios, which would obtain at finite Mach numbers but the trends with geometrical changes should be reasonably reliable.
Estimating Jet Noise
Authors: Coles G. M.
Published: July 2016

A large number of far-field jet noise measurements obtained over a considerable period of time are presented, correlated in such a manner that they may be used to provide a complete noise assessment for any jet of which the performance parameters are known. The data are presented in two sections, one dealing with the problem of a static source near ground level, the other dealing with the case of a source in flight.

Much of the data was derived from Avon engine tests, but a wide range of other jet noise sources has also been encompassed. Comparisons are drawn which show good correlation to exist between the overall sound pressure levels produced by jets of all sizes. It appears also that even the spectra quoted, which are based only on Avon measurements, are valid over a fairly wide range of jet sizes and are not peculiar to the Avon engine.
An Anomaly in the Theory of Tunnel-Wall Interference on a Lifting Wing
Authors: Garner H. C. , Holder D. R. , Acum W. E. A.
Published: July 2016

There appear in the literature some discrepancies in the various mathematical expressions for the upwash constituting the wall interference on a small lifting wing placed symmetrically in a rectangular tunnel with closed side-walls and open floor and roof. The representation of the interference field as that of a doubly infinite array of image doublets is shown to lead to divergence. An independent calculation by relaxation confirms the correctness of an analytical solution by expansion in Fourier series. The discrepancies are found to arise from incomplete flow conditions at the open boundaries, and it is shown in this paper how the various theories are reconciled.
A Simple Model Representing Internal Damping in Solid Materials
Authors: Neubert H. K. P.
Published: July 2016

Based on earlier theories of mechanical, electrical and magnetic relaxation phenomena, the paper discusses a simple mathematical model representing qualitatively the basic characteristics of “internal” damping in solid materials. The model is assessed with respect to variation with frequency of stiffness and loss factor at simple harmonic oscillations, and is applied to oscillatory systems with discrete parameters and to continua.
Stress Concentrations for Uniformly Reinforced Equilateral Triangular Holes with Rounded Corners
Authors: Wittrick W. H.
Published: July 2016

The stress concentration factors for equilateral triangular holes, with varying degrees of curvature at the corners, and with varying amounts of compact reinforcement on the boundary, have been computed for each of three loading cases. Poisson's ratio was assumed to be 1/3.
The Static Aeroelastic Deformation of Slender Configurations
Authors: Hancock G. J.
Published: July 2016

The concept of the manoeuvre margin is discussed, and definitions are suggested which are applicable to all types of configurations. Calculations are presented for the manoeuvre characteristics of simplified flexible models representing conventional and slender integrated aircraft. Linear aerodynamics only are assumed.
The Turbulent Jet from a Series of Holes in Line
Authors: Knystautas R.
Published: July 2016

The possibility of obtaining two-dimensional turbulent jet flow from a series of closely-spaced uniform holes in line has been investigated both theoretically and experimentally. The case studied was that of a jet discharging into still fluid of similar density at incompressible speeds. Such a quasi-two-dimensional jet is a particular example of a multiple-interfering jet group.
The Effects of Introducing a Restoring Moment Proportional to Stick Velocity on the Hovering of an Unstabilised Jet-Lift Aircraft
Authors: Holden K. J.
Published: July 2016

This paper covers an investigation into a new way of assisting the pilot to hover an unstabilised jet-lift aircraft. In a normal control system the aircraft is controlled by a moment which varies linearly with stick position. In this paper control systems were considered in which the controlling moment was a linear function of the position and rate of change of position of the stick. The investigation was primarily limited to optimising such a system with freedom restricted to rolling motion and the associated lateral displacement. Effects of limited control power and engine failure were considered. With the optimum control the mean errors in position recorded when hovering were under half those achieved with a normal manual control and the results were almost as good as for an ideal rate-stabilised aircraft. Extending the investigation to both pitch and roll planes led to an even greater improvement, even when the effects of gyroscopic coupling between the two planes were taken into account. The precise engineering of a “mixed” control system of the type discussed needs much thought and it will require considerable development, but the results achieved indicate that it may prove an attractive alternative to an autostabiliser
Stress Distribution in Rotating Discs with Non-Central Holes
Authors: Green W. A. , Hooper G. T. J. , Hetherington R.
Published: July 2016

The stress distribution in rotating circular discs containing a central hole and a symmetrical array of non-central holes is determined by numerical solution of the equations of generalised plane stress. Particular attention is given to an annulus containing the holes and of width approximately eight hole diameters, in which the full two-dimensional equations are solved. The region outside this annulus is treated as radially symmetric and the stresses there are determined from a simpler one-dimensional model. Stress distributions are reported for uniform discs of fixed geometry containing 10, 20 and 45 holes. Results are also obtained for 20-hole discs of non-uniform thickness comprising a uniformly tapered disc, a disc with a thickened annulus containing the holes, and a uniform disc with each hole surrounded by thickened bosses. As a check on the numerical method, calculations have been carried out on a disc of identical geometry to one examined photoelastically bv Leist and Weber with good agreement. The effect of changing Poisson's ratio for this particular disc is also examined.
Electrical Analogue Solutions for the Deformation of Skew Plates
Authors: Rushton K. R.
Published: July 2016

A study has been made of the deformation of skew slabs using a pure resistance electrical analogue with a square mesh. The three commonly occurring boundary conditions of simply-supported, clamped, or free edges have been represented on the analogue, and the results of typical problems with these edge conditions are given.
Influence of the Torsional Rigidity of Transverse Stiffeners upon the Shear Buckling of Stiffened Plates
Authors: Rockey K. C. , Cook I. T.
Published: July 2016

The paper provides relationships between the buckling resistance of simply-supported transversely stiffened plates and the flexural rigidity of the stiffeners for various values of the ratio of torsional rigidity to nexural rigidity. Results are presented for four different stiffener spacings.