bluuebunny/crossref_metadata_2025 huggingface dataset:
Problems and Progress in Aircraft Design
Authors: Farren W.S.
Published: February 2008

IF variety is the spice of life, then aircraft engineers have little to complain of in their experience of the last twenty years. It is true that most of the hopes of a sane world, with which we set out after the first war—a world in which aircraft would be a powerful influence for good —were wearing a bit thin in 1929. It was becoming clear that only the few could afford to fly. There was little prospect of a demand for aircraft as private or public transport vehicles on a scale which would provide a healthy basis for a free competitive industry. Possibly the most surprising phenomenon of those times of depression was the survival of so many aircraft concerns. In the succeeding years—Mr Churchill's ‘locust years’ 1931–35—darkened by the shadow of coming catastrophe, the meagre defence requirements provided a means of existence. Research, fostered by a few brave spirits, not only lived but made notable strides. Above all, the creative genius of engineers contrived to find means of producing the vital advances upon which, from 1936 onwards, rearmament in the air was founded.
A Tailless Research Aircraft
Authors: Cox W.J. , Siddall J.N. , Stephenson T.E.
Published: February 2008

FOR some years there has been proceeding, under the auspices of the National Research Council of Canada, an investigation of the control and stability characteristics of tailless aircraft. Because of the difficulties inherent in other methods of investigation, the work is being done in flight, using a glider.
Simplified Tooling with Plastic Laminate
Authors: Wilkin Perry Harry
Published: February 2008

TIME spent and expense incurred in making jigs, fixtures and some other production tools have been reduced substantially during a tooling simplification programme conducted for more than five years by the Republic Aviation Corporation, of Farmingdale, NY, USA.
Shock in Valve Mechanisms of Internal Combustion Engines
Authors: Ing.
Published: February 2008

THE evolution of internal combustion engines proceeds steadily ahead, with unceasing improvement in all parts. One group of details, which is most subjected to research, is the valve mechanism, controlling the passage of gases through the cylinder. It is the main purpose of valves to allow the maximum volume of gases in a unit time to flow through the intake and exhaust pipes and to assure the highest possible output of the engine.
An American Gas Turbine of Low Power
Authors: Perry H.W.
Published: February 2008

A LOW‐POWER gas‐turbine engine developed by the Boeing Airplane Company and the reasons for its evolution were des‐cribed by S. D. Hage, chief of the company's propulsion development unit, at the annual meeting of the Society of Automotive Engineers in Detroit last January. When the U.S. Air Forces invited proposals late in 1943 for a medium bomber driven by high‐speed turbo‐jet engines, the development of gas turbines was in such an early stage that not enough practical information was available from manufacturers to meet the needs for designing an aircraft to take maximum ad‐vantage of this type of power‐plant, so Boeing decided to make a thorough study of the new engine type, developing one of small size to keep the cost of research as low as possible.
Aircraft Engineering Reference Sheets
Authors: Tonkin T.
Published: February 2008

The Gemini is a four‐seater wooden aeroplane designed for service on personal, club or taxi duties. Dual controls can be fitted and glider‐towing equipment can also be installed. The data which follow are for the standard model, but various alternative installations and equipment are listed at the end.
Two‐Spar Wing Stress Analysis
Authors: Goodey W.J.
Published: February 2008

THE methods of wing stress analysis at present in use have in most cases been developed on the assumptions that the ribs are rigid in their own planes, and that they may be considered equivalent to an infinite number of infinitely thin ribs, infinitely closely spaced. The problem may then be treated by the methods of the calculus, as was done, for example, in an article by the writer in AIRCRAFT ENGINEERING, January and February, 1943. A more recent and much more comprehensive paper on the same subject has been published by J. Hadji‐Argyris and P. C. Dunne in the R. Ac. Society Journal, February, September and November, 1947, and May and June, 1949.
The Efficiency of Compression in a Single Adiabatic Shock
Authors: Morley A.W.
Published: February 2008

THE increase of pressure in a shock wave takes place with a gain of entropy, so that the efficiency of the compression is less than unity. In this paper we give the results of some calculations of the efficiency of the compression in a single adiabatic shock wave, when no heat is released as the result of any physical or chemical changes in the flowing gas. The efficiency is defined as the ratio of the work done to compress the gas (from the static conditions ahead to the total head conditions downstream) to. the work done if the process were carried out isentropically. Results are given for two values of the ratio of specific heats, i.e. 1.40 and 1.33, which correspond roughly to atmospheric air and turbine gases respectively.
The Brabazon II Rear Spar Frame
Authors: Morgan A.W.
Published: February 2008

THE rear spar frame, the first major member forward of frame ‘O’ forms, together with the front spar frame, the principal structural links between the inner wing and fuselage, bearing the loads imposed upon the inner wing and dispersing them into the fuselage. Constructionally, therefore, the frame is necessarily robust comprising a double diaphragm structure, spaced apart by heavy boom sections of light aluminium alloy situated around the inner and outer frame peripheries. The centre section of the frame is extensively cut away, leaving a diaphragm width of approximately 16 in. at the fuselage datum, tapering to 10 in. at the roof, and 4 in. at the bottom centreline of the aircraft. The lower portion of the frame, 24 in. below the datum is cranked at 3 1/2°, aligning with the wing incidence of the spars. The diaphragms front and rear are made in segments, and lap jointed; the outer edge periphery is flanged forming a skin attachment angle. For the front diaphragm construction, eight segments are utilized, those adjoining the roof and at the fuselage base are fabricated from 16 s.w.g. D.T.D. 546, while around the fuselage dytum 14 s.w.g. D.T.D. 546 is employed. Below the fuslage datum, a gap occurs in the frame segments, which is filled by the web of the rear spar after the frame and spar are brought together as an assembly. This web is 4 ft. deep and straddles the frame across the diameter, leaving a 2 ft. aperture between the top edge of the web and a floor support member. A similar aperture is left between the bottom edge of the web and the frame segments at the fuselage base.
Two‐Spar Wing Stress Analysis
Authors: Goodey W.J.
Published: February 2008

IT was now evident that some other effect would have to be taken into account to obtain a more exact agreement between theory and experiment, and it was fairly obvious that the non‐rigidity of the wing root attachments was the chief cause of the discrepancy. The method of dealing with this is given below, while the numerical results are plotted as curves C in Figs. 7 and 8. It will be seen from these curves that the modification to the theory, which is merely a modification to detail, has the desired effect.
Practice of Shock‐Absorber Design
Authors: Burger F.E.
Published: February 2008

IN a previous article (Ref. 1) the present author outlined some fundamental considerations of general practice. In the present paper the intention is, in effect, to take some pages from a designer's notebook and explain in detail the procedure by which the dynamic characteristics of a leg are determined. A description of one of the author's own designs will provide a suitable area of reference, and although certain of the geometrical calculations will apply rather specially to this, the remainder of the working will be quite general in its application. In particular, the orifice calculations—a vitally useful aspect which has not previously been treated in a practical fashion—have been compared with drop‐test results over a range of differing designs and sizes of shock‐absorber and show very good agreement with them; certainly good enough for a close initial approximation, and in the style of leg described here and in other simple fixed orifice designs, sufficiently accurate to allow of dispensing with dynamic tests provided that tyre and oleo relationships do not diverge too far from the conventional.
An American Development in Cargo‐carrying Aeroplanes
Authors: Perry H.W.
Published: February 2008

AIR freight carried by commercial transport operators has increased rapidly in volume during the last five years, especially since 1947. In the first eight months of 1949, for example, domestic cargo flown out of and into the three major airports in the New York City metropolitan area totalled 74,435,169 pounds—an increase of 21 per cent over the 61,541,098 pounds carried in the corresponding period of This cargo growth in one year compares with an increase of 23½ per cent in passenger traffic—from 2,014,370 air passengers during January‐August 1948, to 2,490,250 in the first eight months last year.
Aircraft Engineering Reference Sheet
Authors: Tonkin T.
Published: February 2008

This comprises a pump on each engine either of which draws air through the gyro‐operated instruments via a change‐over cock (dash‐starboard) and Plessey 215B adjustable relief valves, set to 5 in. Hg. on forward face of each firewall. The suction gauge is on the port side of the dash. If an automatic pilot is fitted, it is connected to the discharge from the port pump, otherwise the pumps exhaust into an oil drain collector box at the bottom of each firewall.
A Hydraulic Static Testing Apparatus
Authors: Haviland J.K. , McCaffrey G.F.W.
Published: February 2008

A HYDRAULIC static testing apparatus has been installed in the Structures Laboratory for the purpose of carrying out static strength tests on aircraft components and other large structures. In the design of this apparatus, an attempt has been made to provide testing facilities which are as complete as possible within the physical limitations imposed by shape and size of the existing building.
The Statistical Analysis of Trans‐Canada Air Lines
Authors: Jaworski Adam
Published: February 2008

STATISTICS, defined as ‘numerical facts systematically collected’, was in the industry from the first day of its working. Statistical analysis, based on probability calculation, was introduced into the factories, on a large scale, during the last war under the term ‘Quality Control’.
The Development of the Lockheed P2Y Neptune
Authors: Wassall J.B.
Published: February 2008

BACKGROUND IN the early stages of World War II the U.S. Navy used the Lockheed PV‐1 (Ventura) in considerable quantities as a land‐based patrol plane for anti‐submarine and anti‐surface vessel patrol and attack. Inasmuch as the PV‐1 was the first high speed land based patrol aeroplane used by the U.S. Navy, and realizing that its aero‐dynamic configuration grew out of the commercial Lockheed Lodestar, it can be understood that its tactical utility was a compromise.
The Analysis of Structures Consisting of Curved Members of Variable Section
Authors: JONES B.D. , SARAVANOS B.
Published: February 2008

THIS was the subject of an article by Mr B. Saravanos, A.F.R.Ae.S., in AIRCRAFT ENGINEERING, January 1950, pp. 24 and 25. The writer has worked out equations which differ from the article. These differences are discussed below.
Vibration in Composite Beams
Authors: Krzywoblocki M.Z.
Published: February 2008

AN aeroplane wing and fuselage may be treated from an analytic standpoint as two elastic beams, rigidly connected. In the present note the equations for the natural frequency, derived on the basis of Rayleigh's principle and Ritz's method, are extended to the case of free vibration of a set composed of two such beams with a number of concentrated loads elastically suspended.
The Development of the Avro C102 Jetliner
Authors: Floyd J.C.
Published: February 2008

ON August 10, 1949, the Avro C102 jet transport, now better known as the Jet‐liner, made its first flight.
A Solution to the Problem of Torsion‐Flexure
Authors: Mordellet R.L.
Published: February 2008

FOR the past fifteen years nearly all aircraft structures have been of the shell or stressed‐skin type and problems pertaining to this type of structure have been steadily tackled and finally solved for practical use by the designers.
An Improved Casting Process with Resin‐Sand Moulds
Authors: Perry H.W.
Published: February 2008

INCREASED production, reduced cost and better quality of castings are advantages claimed for a new process which was demonstrated during the week of May 8–12 at the 1950 National Foundry Show in Cleveland, Ohio, U.S.A. The demonstration included production of moulds and pouring of metal by representatives of the Bakelite Division of the Union Carbide & Carbon Corporation.
Aircraft Engineering Reference Sheet
Authors: Tonkin T.
Published: February 2008

The pneumatic system operates the undercarriage, wheel brakes, flaps, windscreen wipers, fuel priming pumps and air intake shutters, Fig. 7 and its accompanying key show the principal features and the location of the major components where this is not obvious.
The Steepest Angle of Climb of Jet Aeroplanes in Unaccelerated Flight
Authors: Järvineva Elias
Published: February 2008

WE first derive for jet aeroplanes the formulae for the least thrust sufficient for a specified angle of climb. In the mathematical derivation of formulae we make use of the method represented by H. Freeman in J. of Ae. Sci. No. 3/1947, ‘Simple Analytic Equations for the Velocity of an Aeroplane in Unaccelerated Level, Climbing and Diving Flight’. We then see that through a simple deformation the equations can be brought into such a form as to make it possible to represent the steepest climbing angle, the corresponding flight velocity and the rate of climb obtainable at a specified thrust by means of a combined, very simple, dimensionless vector diagram.
Airflow Patterns in the Neighbourhood of Helicopter Rotors
Authors: Meijer Drees Ir. J. , Hendal Ir. W.P.
Published: February 2008

In this paper results arc discussed of wind‐tunnel smoke tests with a small helicopter rotor. The test apparatus includes a specially developed hot‐wire smoke‐generator. An attempt is made to describe the flow pattern in the neighbourhood of a helicopter rotor in the vortex ring state by introducing the spread of the slipstream, causing an airbody around the rotor. By considering the proportions of this airbody the unpleasant behaviour of helicopters in the partial power‐off descent at low forward speeds can be more clearly understood.
An Application of the Escalator Process
Authors: Morris J.
Published: February 2008

The escalator process is shown to be easily applicable to certain frequency equations of Hermitian character which have been encountered in such problems as the whirling of contra propeller systems and the mechanical vibration of an aircraft.
The Estimation of Wing Weight
Authors: Solvey J.
Published: February 2008

This paper suggests a means of estimating wing weight using formulae based on the theoretical ideal wing. The predicted wing weight is attained by multiplying the weight of the ideal wing by a correction factor derived from a statistical analysis of actual wing weights. The method has the advantage that it provides the designer with a yardstick by which to compare alternative designs and indicates where improvement might be effected.
Representing the British Aircraft Industry
Authors: Bowyer E.C.
Published: February 2008

THE Society of British Aircraft Constructors was incorporated as a company, limited by guarantee and with no share capital, on March 29, 1916. It is, therefore, junior to the Royal Aeronautical Society and the Royal Aero Club, but senior by two years to the Air Ministry and the Royal Air Force, and the elder of many other official, semi‐official and commercial organizations which the expansion of aviation has brought into being during the past thirty‐five years. The Society is young enough to retain within its counsels today many who were well‐known and active in the industry in the time of formation; old enough to have acquired a body of experience unique in its field and for its records to begin to qualify as history, of which some aspects at least carry interest worthy of the columns of AIRCRAFT ENGINEERING.
The Determination of Orifice Parameters for Shock Absorbers
Authors: Nightingale J.
Published: February 2008

THE determination of orifice parameters was discussed in great detail in an article by G. A. Dirac, ‘The Explicit Determination of Orifice Parameters in Shock Absorbers’, published in AIRCRAFT ENGINEERING, Vol. XIX, August 1947, pp. 258–262. The methods there suggested involve a great deal of numerical work, and it has been felt that some rapid approximate method for determining the orifice parameter would be more satisfactory. The present article represents an attempt to obtain a simple explicit relation for this parameter.
The Rapid Discharge of Gases from Vessels
Authors: Kestin J. , Glass J.S.
Published: February 2008

EXPERIMENTS on the rapid discharge of gases from cylinders show marked deviations from the accepted quasi‐steady theory. Agreement between experiment and calculation is obtained at the cost of assuming very large coefficients of discharge. It is shown in the present paper, that the discrepancies are due to the fact that the mass discharge is larger than that implied by the quasi‐steady theory, mainly owing to the omission of the considerable velocity of approach. The application of the wave theory of gas mechanics to the case of rapid discharge is sketched and it is shown that the deviations from the quasi‐steady theory predicted by it are of the same order of magnitude, as found experimentally.
Landing Loads on the Bogie Undercarriage
Authors: Foster S.
Published: February 2008

THE undercarriage considered consists of a telescopic main shock absorber to the bottom end of which is pivoted a beam carrying at its extremities wheel assemblies consisting of one, two or more wheels on a common axle. Free movement of the beam is prevented by the action of an auxiliary damper located between a point adjacent to the rear axle and a point on the beam pivot fitting. The function of the auxiliary damper is to reduce the oscillatory tendency due to unbalanced loading of the rear or front wheels and to locate the beam during flight. The damper is preferably double‐acting.
A Review of Helicopter Patents
Authors: Hay ward L.H.
Published: February 2008

ACCORDING to historical records the earliest known drawings for an aerial machine that can be classified under the heading of helicopter were made in the fifteenth century by the world renowned Italian scientist and artist Leonardo da Vinci (1452–1519). Probably the Chinese had been making their helicopter toy for some considerable time before da Vinci commenced his experiments. This toy consisted of two feathers, joined together by means of a cork or soft wood boss, to form a crude type of propeller which was pushed up a threaded stick so that upon leaving the stick the propeller rotated at high speed and continued to screw itself up in the air. When the speed of rotation decreased the propeller slowly windmilled down to the ground. A similar toy is still being sold today.
Pre‐tensioning for Preventing Fatigue Failure in Bolts
Authors: Fisher W.A.P. , Cross R.H. , Norris G.M.
Published: February 2008

The prevention of fatigue in bolts by controlled pre‐tensioning is investigated theoretically. It is shown that the effect of pre‐tension is to reduce the alternating load in the bolt and that the stiffness of the fitting plays an important part in this reduction. Fatigue tests on ¾‐in. B.S.F. bolts with various amounts of pre‐tension show how this reduction in alternating load can prevent fatigue failure. A warning is given against relying on the benefits of pre‐tensioning without ensuring that pre‐tension is maintained in service.
Development of the Ambassador De‐icing System
Authors: Newbigin H.G.
Published: February 2008

WHEN the original design of the Ambassador's thermal de‐icing was conceived very little practical experience had been gained on such systems in this country, and almost no theoretical data were available. Little or no development had been carried out on the numerous new components involved, so much credit must be given to the initial project work of the Airspeed design team (in particular Mr W. T. Blanchard), and of Radiation Limited (design of the combustion heaters), which resulted in no fundamental changes having to be made during the Ambassador development trials, although a considerable number of refinements were necessary.
High Strength Light Alloys
Authors: Giles P.G. , Kiddle P.F.
Published: February 2008

THE necessity for the development of high strength structural alloys was accentuated by the rapid development of the jet engine, a power unit which brought the speed of flight to within reach of the speed of sound. This major step in engine potentiality put a new urgency on the need for high strength structural alloys to be placed at the disposal of the designer. This deficiency was diminished to a large extent by the production of the aluminium‐zinc‐magnesium‐copper alloys. Once the potentialities were realized of this type of alloy having tensile strengths equal to the low carbon steels and a strength/weight ratio substantially superior to the aluminium‐copper alloys, it found widespread application for primary aircraft structures. The approximate chemical composition of the (Al‐Zn‐Mg‐Cu) alloys is given in table i and compared with that of the Al‐Cu or duralumin type alloys.
The Library Shelf
Authors: D.W.  , J.Z.
Published: February 2008

The author of this book, Dr W. F. Hilton, has been an enthusiastic worker in the field of high speed flow for more than twenty years, and has had unusually wide experience of high‐speed problems. Indeed, the reviewer believes that Dr Hilton, in his work on propellers with high tip speeds, was the first person to obtain photographs of shock waves generated by an aeronautical body: shock waves generated by missiles were, of course, well known. Any work on high speed flow from his pen must, therefore, be examined with great interest and anticipation.
Undercarriage Performance During Landing
Authors: Hazard R.F.
Published: February 2008

IT has been said that the trouble with a mathematical solution to an industrial problem is that it is, only too often, an exact solution to another problem. This state of affairs has arisen because of the number of simplifying assumptions that arc usually necessary before such a mathematical solution may be attempted. However, the writer holds the view that a mathematical solution tends to throw light upon the problem of design and hence, even when a number of assumptions are made, the results may serve as a guide to the designer where otherwise guess‐work, inspired by experience, would be the only course.
Strength Tests by Towing in Water
Authors: Braun Winfried
Published: February 2008

A strength testing method formerly used in Germany is described. Aircraft components were towed under water in a large tank so that loads were produced on the specimen equivalent to those realized under actual flight conditions. Advantages of the method were that no special means for transmitting forces to the specimen were needed and that all changes of the air loads resulting from elastic deformation were automatically included in the applied loading. Particulars arc given about tests made on cabin hoods, tail planes and on one wing. Future possibilities of testing whole aircraft and of conducting research into the effects of clastic deformations on stabilitity characteristics are discussed. The limitations of the method arc given, especially with regard to the absence of compressibility effects. The opinion is advanced that despite these limitations further development of such testing methods should be considered.
The Peeling Test on Redux‐bonded Joints
Authors: Spies G.J.
Published: February 2008

A theoretical analysis is given of the peeling test for Redux‐bonded joints, as devised by Aero Research Ltd. and generally accepted as a standard quality control test for metal‐bonding processes. Numerical values derived from computations appear to be in reasonable agreement with experiments, but more test‐data and better knowledge of the clastic and plastic behaviour of both adhesive and adherent are necessary to make the method more reliable in this respect. The practical value of the method, however, is the indication it gives about the sensitivity of the test for the variables involved. This may make it feasible to introduce corrections for variations of some parameters, thereby improving the reproducibility of the test.
The N.A.C.A.'s Role in Guided Missile Research
Authors: Shortal Joseph A.
Published: February 2008

THE role of the National Advisory Committee for Aeronautics in the present national effort devoted to the development of guided missiles is quite similar to the role the N.A.C.A. has taken for many years in connexion with piloted aircraft. This role, as specified by Congress in 1915, is to ‘supervise and direct the scientific study of the problems of flight with a view to their practical solution’. While the advent of guided missiles has naturally introduced some new aerodynamic problems, many of the problems are the same as those of piloted aircraft. The chief job of the N.A.C.A. is to find solutions to these problems and to supply the information necessary for the scientific design of aeroplanes and missiles. The present interest in both types of aircraft covers subsonic speeds, transonic speeds, and supersonic speeds. The N.A.C.A. has three laboratories devoted to this research. These laboratories are located at Moffett Field, Calif.; Cleveland, Ohio; and Langlcy Field, Va. Each of these laboratories has wind tunnels and other facilities devoted to the guided missile effort. Since the wind‐tunnel work of the N.A.C.A. is well known, 1 would like to review a lesser‐known programme being conducted by the N.A.C.A.'s Langley Laboratory by means of rocket‐propelled test models at its Pilotless Aircraft Research Station at Wallops Island, Va.
Wing Structures of Future Aircraft
Authors: Ljungström Olle
Published: February 2008

IT is the purpose of this article to present some ideas about future trends in wing design for high speed aircraft and to discuss briefly some of the many difficult problems which the designers will have to deal with in producing such rugged but in many respects extreme structural shapes as will be required for successful aircraft of the transonic and supersonic era.
Efficiency and Drag of an Axial‐Flow Compressor Stage
Authors: Stephenson J.M.
Published: February 2008

THE performance of an axial‐flow compressor is most easily analysed in terms of the characteristics of each stage, by which is meant each pair of blade rows. Usually one row rotates on a central shaft and the other is fixed to an outer casing.
The Slingsby Sky High‐Performance Sailplane
Authors: Reussner J.R.
Published: February 2008

THE Slingsby Sky is a British designed high‐performance sailplane and is intended for cross‐country and competition flying. The prototype Sky first flew in the summer of 1950 and since that time the design has been put into limited production. The Sky has obtained several notable successes in competition flying, the most recent of which was the 1952 International Gliding Contests in Spain, where Sky's took the first, third and fourth places; the six machines which completed the contest all being placed in the first fourteen out of a total entry of forty.
Approximate Solution of Non‐Linear Equations
Authors: Nightingale J.M.
Published: February 2008

THE modes of a dynamical system are defined by its equations of motion. For instance, the response of a simple linear system to a periodic external force is completely specified by an equation of the type
The Strength of Metal Joints, Made with Synthetic Resins
Authors: Frey K.
Published: February 2008

The use of synthetic resins as adhesives for metals or other non‐porous materials, in which there is increasing interest for structural and production reasons, imposes certain restrictions on the components bonded and the type of joint used. In the following paper the general points applicable to adhesive joints are first considered. A large number of strength measurements on simple light alloy lap joints made with ‘Araldite’ by the Eidg. Materialprüfungs und Versuchsanstalt (E.M.P.A.) are used to analyse the manner in which the breaking load under tensile shear loading depends on the geometry of the test specimen. It can be shown that in this special case, which is however of importance in practice, there is an optimum utilization both of the adhesive and of the metal, whose yield point determines the choice of sheet thickness and overlap. The use of synthetic resins as adhesives for metals and other non‐porous materials opens up numerous new developments and possibilities in a whole range of industries. Although comparatively new it has already found many practical applications which steadily increase.
A Method of Estimating Helicopter Performance
Authors: Payne P.R.
Published: February 2008

Based fundamentally on the ‘Energy Method’ approach to helicopter performance calculation, a method is presented for calculating performance of a design in the project stage. In another form, less suitable for project work, the equations have been used for performance estimation by the writer for several years. They were found to give better agreement with flight test and rotor tower results than any other method tried. It is believed that the method gives quicker and more accurate results for project work than any so far developed.
Contribution to the Structural Analysis of Swept Wings
Authors: Bodet Pol
Published: February 2008

THE St. Venant theory as applied to long beams of constant cross‐section could generally be used with sufficient accuracy for the solution of the structures encountered in aircraft until the last few years. The wings of high‐speed aircraft, with smaller aspect ratios, large angles of sweep‐back, and small thickness/chord ratios, introduce a new problem. There is an extensive literature on the subject, and all the methods which have been proposed are necessarily studies of redundant systems, the degree of redundancy varying according to the accuracy required. As these solutions require that the scantlings of the structure be known in advance, it was thought interesting to establish a simple method which would determine to a good approximation the skin thicknesses required. This is based on the application of the theorem of least work, which gives exact solutions of elasticity problems so long as all the terms in the strain energy expression are taken into account.
A General Theory of Helicopter Rotor Dynamics
Authors: Payne P.R.
Published: February 2008

BECAUSE of the complexity of rotor theory which has been developed for tapered and twisted blades (for example, Sissingh's well known papers) there is a great tendency to use and draw conclusions from the simple theory developed for untwisted untapered blades. In the United States this practice appears to be almost universal, and much use is made of the highly questionable ‘equivalent chord’ when dealing with tapered blades. It cannot be too much emphasized that there is no such thing as an ‘equivalent chord’, and that its use not only masks the true effect of taper, but leads to solutions which in some cases are in considerable error.
The Service Life of Aircraft Structures
Authors: Turner F.
Published: February 2008

The ultimate aim of the stress calculation of aircraft structures is to reduce the frequency of defects in service to an acceptably low level. If this is to be done without undue structure weight the design loads, the factors of safety and the allowable stresses must be chosen with great care. In principle, there must be some relation between the probability of failure and the design strength. On a new design this function is always unknown and the designer must rely on experience of previous aircraft to guide his judgment. However, the required service life and the expected conditions of service, including temperature effects, vibration, etc., must be foreseen and taken into consideration.
Sponsored Research on Light Alloys
Authors: Thomson A.G.
Published: February 2008

PROMINENT members of the aircraft industry were among more than 300 people present at the Fulmer Research Institute, on November 2, when a new engineering laboratory was opened by H.R.H. the Duke of Edinburgh.
Hub Moments and Forces of a High Offset Rotor
Authors: Payne P.R.
Published: February 2008

In Ref. (1) the dynamics of a rotor with high offset flapping hinges were considered, for twisted and tapered blades with ?3 coupling between flapping and feathering. In the present paper simple expressions are derived for the hub pitching and rolling moments of such a rotor, and it is shown that these moments must be balanced either externally (by aerodynamic surfaces for example) or internally by suitable inclination of the mechanical axis (Eqs. (7) and (8)). The relevant expression for total rotor moment is given in Eq. (17). In order to arrive at a solution, the vertical force acting on a single flapping pin was evaluated, and this is given by Eq. (5). This is particularly interesting, apart from stress calculations, in that it shows the mechanism whereby a blade which is out of track in the tip path plane can cause a first harmonic vertical vibration in forward flight. It is shown that a two‐bladed high offset rotor will always experience second harmonic hub vibration unless it is balanced out by inclination of the mechanical axis. In general, the mechanical axis position is seen to be an important parameter in both vibration and hub moments; a fact which has hitherto passed unrecognized except for some unpublished work at the Royal Aircraft Establishment by Mr P. Brotherhood. This does not necessarily imply that mechanical axis inclination is a panacea to cure all ills. By far its most useful effect lies in suppressing in‐plane vibration, to which vertical vibration is usually of second order importance. This is, of course, a separate subject.
Symposium on Powder Metallurgy
Authors: Thomson A.G.
Published: February 2008

A SYMPOSIUM on Powder Metallurgy, organized by the Iron and Steel Institute in association with the Institute of Metals, took place in the Hoare Memorial Hall. Church House, Westminster, early in December.
The Design and Execution of Electrical Installations
Authors: Brookesmith F.B.
Published: February 2008

IN this paper an attempt is mads to give some guidance as to what is needed for a modern aircraft electrical installation. The subject is extremely wide, and the electrical installation designer must have knowledge, not only of the methods of installing cables and equipment, but of the electrical requirements of the aircraft, the means of obtaining the power, and of controlling and distributing the energy to the best possible advantage. He must also know the needs peculiar to airborne conditions, the way to obtain a clear and precise presentation for operation and servicing, the proper source of the varied materials and equipment, and be capable of the design of items which are not otherwise obtainable. He must be able to direct his staff so that instructions are issued in the form of drawings which are as concise and as simple as possible.
Helicopter Rotor Vibration in the Tip Path Plane
Authors: Payne P.R.
Published: February 2008

In‐plane vibration of a balanced helicopter rotor is caused by variations with azimuth of the in‐plane forces acting on individual blades. These forces may be summarized under three headings: ‘Induced forces’ caused by the inclination of elemental lift vectors relative to the axis of rotation. ‘Profile drag forces’: variations are caused by changes with azimuth angle of the angle and airspeed of the individual blade elements. ‘Coriolis forces’, which are caused by blade flapping, which brings about a variation of blade moment of inertia about the axis of rotation. Equations are developed in this paper for the resultant hub force due to each of these forces, on the assumptions of small flapping hinge offset. It is assumed that blades are linearly twisted and tapered, an assumption which in practice can be applied to any normal rotor. It is shown that by suitably inclining the mechanical axis it is possible to balance out the worst induced and profile drag vibrations by the coriolis one, which can be made to have opposite sign. If the mechanical axis is fixed in the fuselage, this suppression is fully effective for one flight condition only. In multi‐rotor helicopters, vibration suppression can be extended over a much wider range by varying the fuselage attitude. The logical result of this analysis is, for single rotor helicopters, a floating mechanical axis which can be adjusted or trimmed by the pilot. This would be quite simple to do on a tip‐driven rotor, and has already been achieved with a mechanical drive on the Doman helicopter. The more important causes of vibration from an unbalanced rotor are next con‐sidered, attention here being confined principally to fully articulated rotors, which are the most difficult to balance because the drag hinges tend to magnify all in‐accuracies in finish and balance. From a brief discussion of the vertical vibration of an imperfect rotor it is shown that some contemporary methods of ‘tracking’ are fundamentally wrong. Finally the vibration due to tip‐mounted power units is described. In discussing the effect of a vibratory force on a helicopter a simple response chart is developed, and it is thought that its use could well be accepted as a simple standard for general assessment purposes. In the development of equations for vibration the following points of general technical interest are put forward: An equation for induced torque is developed which includes a number of hitherto neglected parameters. A new form of equation for mean lift coefficient of a blade is suggested. The simple Hafner criterion for flight envelopes is shown to give rise to considerable error, and the use of Eq. (28) is suggested in its place. The variation of profile torque with forward speed is given, and the increase due to ? varying round the disk is expressed as an explicit equation, thus allowing considerable improvement in the present methods of allowing for this effect.
Fusion Welding Unalloyed Titanium Sheet
Authors: Levy Alan V. , Wickham Robert
Published: February 2008

The great fluidity of titanium metal in the molten condition lends itself to fusion welding without the addition of filler metal. The resulting welds are flush with the base metal and have high ductility, comparable to the ductility of the base metal. The welded joints can be made by hand or automatic methods. A critical requirement of this type of weld is fit‐up of the parts to be joined. The back‐up and hold‐down fixtures also have a decided effect on the resulting weld. A sheared surface resulting in a joint without gaps is required for a satisfactory weld. Fused welds have been principally used, to date, for longitudinal tight butt joints in material up to .062 in. thick. Further testing and experience should extend the limits of application. Bend tests made on welded samples have bent 180 deg. over a 2T bend radius exhibiting equal or greater ductility than the base metal. Welds tested in tension have exhibited over 100 per cent efficiency in all cases. The elimination of welding rod has reduced the amount of contamination in the weld and the weld area.
Servomechanism Performance
Authors: Morris J. , Gouriet G.G. , Head J.W.
Published: February 2008

The problem of rotating a single large mass through a given angular distance so that the performance shall meet given specifications is considered. Initially it is assumed that the general nature of the torque which can be applied is prescribed, but that certain parameters are at our disposal; the practical determination of the best values of the parameters is considered. For the analogous electrical problem, this is equivalent to determining the best values of certain resistances, capacitances and inductances in a given network containing variable elements. But in order to solve the problem it is more effective to make alterations and additions to the network, so that it becomes equivalent to one having the required performance, and the way in which this can be achieved for the single rotating mass is discussed. The restriction to a single‐mass system is merely for convenience and simplicity; the procedure here discussed is perfectly general.
The Stiff‐hinged Helicopter Rotor
Authors: Payne P.R.
Published: February 2008

THE continual development of helicopter rotor systems has so far resulted in the use of about six main types, and it will be of value briefly to recapitulate their advantages and disadvantages in order to obtain a balanced picture against which the stiff‐hinged rotor can be judged.
American Experience with Magnesium Alloys
Authors: Wilkin Perry H.
Published: February 2008

AN all‐magnesium aircraft has been built in the United States by East Coast Aeronautics Inc. under contract to the Air Force Air Development Center. It is the latest in a series of projects connected with the use of magnesium for aircraft primary structures. J. P. Donald Garges, vice‐president of the company, gave a detailed account of these projects in a paper presented to the Institute of Aeronautical Sciences at its annual meeting in January 1955, and published in Aeronautical Engineering Review in August 1955.
Induced Aerodynamics of Helicopters
Authors: Payne P.R.
Published: February 2008

THE simple actuator disk theory, first postulated by Froude over sixty years ago, is the basis of most helicopter induced flow theory. This disk is an idealization of a rotor which uniformly accelerates the air with no loss of thrust at the blade tips. It can therefore be regarded as the limit case of a rotor with an infinite number of blades. It is also assumed to be infinitely thin so that no discontinuities in velocity occur on the two sides of the disk.
Aeroelastic Problems of Low Aspect Ratio Wings
Authors: Woodward F.A.
Published: February 2008

A method is presented for calculating the aerodynamic forces acting on an elastic supersonic wing having arbitrarily swept straight leading edges and a supersonic trailing edge. The loads are presented in matrix form in terms of the geometrical incidence effective at given wing structural stations. It is thus possible, by combination with the corresponding structural matrix, to determine the steady state aeroelastic loading and final shape of the wing. It is shown how the distribution of loading associated with the placing of incidence on a small quadrilateral area within the wing plan form may be calculated. This loading is broken down into point loads acting at the required structural stations by graphical integration. The loading due to each small area is built up by superposing solutions obtained from linearized supersonic control surface theory. The sweep of the hinge line, and its relation to the wing Mach lines and leading edges are the main parameters of the problem. Twelve formulae are presented, giving the loading in each of the various regions likely to occur for practical wings. By a proper combination of the loads acting on symmetrically opposed stations on each side of the wing, the symmetric or anti‐symmetric aerodynamic matrix can be formed, corresponding to pitching and plunging, or rolling motions of the wing respectively.
Second A.G.A.R.D. Combustion Colloquium
Authors: Bragg S.L.
Published: February 2008

THE second Combustion Colloquium organized by the A.G.A.R.D. (Advisory Group on Aeronautical Research and Development to the N.A.T.O. Countries) was held at the University of Liege, in Belgium, on December 5–9 last, and was attended by about 200 delegates. The seventeen papers which were presented and discussed were grouped under the following headings, although their subject matter sometimes overlapped these boundaries:
Performance Criteria of Gas‐Turbine Combustion Chambers
Authors: Spalding D.B.
Published: February 2008

The paper is mainly concerned with how the gas‐turbine designer can choose the best design of liquid or gaseous fuel combustion chamber for his purpose. In the method proposed, combustion chamber test data are expressed in a way which gives the most general information about the design, by introducing dimensionless performance criteria. These criteria are then plotted in ways which enable the various chamber designs to be compared. The treatment deals implicitly with the conditions which satisfactory model tests must fulfil. An idealized model of a gas‐turbine combustion chamber is introduced in the light of which the effects of changes in overall fuel/air ratio can be explained more satisfactorily than when conditions in the flame‐tube are supposed homogeneous.
Induced Aerodynamics of Helicopters
Authors: Payne P.R.
Published: February 2008

HELICOPTER performance methods currently in use fall into two main groups. The smallest is typified by Refs. and, and evaluates performance by considering the forces acting on each element of the blade. To do this it is first necessary to determine the flapping and pitch angles of the rotor, and then to integrate the elemental forces. The equations thus developed are much too complicated for design office use, and simplifications such as Ref. are achieved only at the expense of limiting the work to untwisted and untapered blades. Moreover the basic theory so far published is incomplete since it is tacitly assumed that the rotor thrust is normal to the no‐feathering axis or the tip path plane.
Performance Criteria of Gas‐Turbine Combustion Chambers
Authors: Spalding D.B.
Published: February 2008

Typical performance data for combustion chambers with separate introduction of fuel and air have already been presented in FIG. 1. Comparison with FIG. 7, typical of one‐stream chambers, reveals some important differences. Firstly, the data are neither confined within the inflammability limits nor have their peak at the stoichiometric O.F.A.R.; the shift is usually towards the weak side. Secondly, the ratio of the maximum O.F.A.R. to minimum O.F.A.R. of a given curve may be many times the corresponding range of a one‐stream chamber. Thirdly, the curves do not all terminate at substantially the same value of combustion efficiency. Particularly the second of these features is of great practical importance, for, in gas turbines, combustion chambers are required to cope with a very wide range of O.F.A.R. and must maintain a high efficiency throughout this range. The possibility of designing for a wide O.F.A.R. range is one of the reasons for using a two‐stream in preference to a one‐stream chamber. Some of the design features influencing O.F.A.R. range will be discussed below.
End Grain Balsa as a Sandwich Core Material
Authors: White J.P.
Published: February 2008

The use in aircraft construction of sandwich panels with balsa wood cores gives a saving in weight with very high tensile and compressive strength, which is maintained over a wide range of temperatures and is uniform in all planar directions. The core is stable under changing temperature conditions, and absorbs little moisture through its exposed faces. Panels made with it can be produced in flat sheets and with single or double curvature, are very stiff, and have a smooth aerodynamic surface. They em be fixed by almost any of the conventional methods.