From the two ‘approximate’ theories of bending—Elementary Theory and Winkler available to designers for the determination of bending stresses in beams having initial curvature, the Winkler approximate solution is the one closer to the exact solution development by Golovin.

Timoshenko and Goodier show a comparison of stresses resulting from the three theories for a beam having rectangular cross-section. It is shown here that the values of bending stresses given by Winkler theory are very close to Golovin's exact results. The difference between the two theories lies in the range of 0·1–3·1 % increasing with the ratio, c/a, of the outer to inner radius of curvature of the beam. The above close relationship between the two theories for a beam of rectangular cross-section is also reported by Ford.

What do we mean by reliability? Mathematically, it is the probability that a piece of equipment will be capable of working when called upon to do so for the time required and under the environment specified, and, if we know the mean time between failures and make certain assumptions about the randomness of the failures, we can derive expressions that will give numerical values of inherent reliability.

In layman's terms, we can say that it is the ability of a piece of equipment, whether it be a small component or a complete aircraft, to be ready to work and to continue to work in the environment for which it has been designed, for as long as the specification requires it to do so and to do this with the minimum amount of maintenance.

Sir George Cayley was a great man, many years in advance of his time and with a grasp of fundamentals which must be the envy of many people, even today. Consider the mental prowess of a man who in the technical environment of 170 years ago, where a 12 hp engine was as shown in Fig. 1, could make the statement that, “The whole problem is confined within these limits, namely, to make a surface support a given weight by the application of power to the resistance of air”; it is truly remarkable. It seems to me that the phrase I have extracted from that statement as a title to this lecture epitomises both the man and the subject.

During the past decade, the theory of optimal control associated with linear multivariable systems having state and output equations of the respective forms

and

has been applied extensively to the design of controllers for a variety of aerospace systems. Such applications of this theory have been mainly concerned with the design of controllers that generate optimal control vectors, ẑ, which minimise performance indices of the form.

where Q and R are positive-definite matrices.

Fatigue tests have been made in constant amplitude loading and in narrow band random loading on FV520B steel lugs of width 27 mm loaded by means of a pin 12·7 mm in diameter. The test frequency was 220 Hz, a mean tensile stress of 309 N/mm2 was used and tests extended for endurances of up to 109 cycles.

For endurances up to 106 cycles there was good agreement between constant amplitude and random loading results with both stresses expressed in root mean square values. Beyond this endurance, the random loading results lay below those obtained in constant amplitude loading. Predictions made using the Palmgren-Miner cumulative damage hypothesis in conjunction with the endurance curve in constant amplitude loading gave good agreement with the results in random loading over the whole range of endurances tested.

The Integral I occurs frequently in aerodynamics. To cite a particular case, Ward has shown that if S(x) is the cross-sectional area distribution of a slender body its wave drag D is given to a first approxition by D = qI/(2π), where q is the kinetic pressure. In this case, S(x) is often defined numerically, and the direct evaluation of I is then complicated by the presence of the logarithmic singularity. Several methods may be employed to avoid this complication. Legendre has recently suggested rewriting I in a non-singular form, which unfortunately is not well suited to numerical work. Here, a method for the evaluation of the unmodified integral is presented.

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.

Curves are presented which, together with a knowledge of the intake performance, enable ram-jet thrust coefficients and specific consumption figures to be obtained quickly and accurately in the range M = 1·0 to 3·0.

The responses of systems, whose equations of motion are linear, to arbitrary applied forces are conveniently calculable by the use of impulsive or indicial admittances. Expressions for these admittances are here given explicity for some simple dynamical chains and the procedure for their calculation in chains with more degrees of freedom is outlined. Some general characteristics of the dynamical chains are also examined.

A detailed survey of a delta wing of 70° sweep has been performed at M = 2.5. The measurements include upper- and lower-surface pressure distributions, schlieren photographs, vapour-screen photographs and surface oil-flow visualisation. The results have been compared with thin-shock-layer theory and various other predictions.

A probe is described which will detect contamination, by driver gas, of the test section flow in a shock tunnel. It is a continuously sampling device, which responds to the difference between the ambient speed of sound in the driver gas and the test gas. The probe is compact, easy to construct, and can be used for detection of driver gas in routine testing. The theory of the probe is explained, and experiments are reported which confirm its effectiveness.

The field of viscosity forces in fluid currents of low viscosity—i.e., high Reynolds number—is frequently confined to a narrow zone in the vicinity of the surface; consequently, calculation can be simplified by the following assumptions :—

1. In the friction zone, customarily called the “ boundary layer,” only the most effective components of the viscosity force μΔω, are considered—e.g., for the x component of this force, μΔu (calling the direction of main flow parallel to the surface, the x direction, and that perpendicular thereto the y direction) the expressions μ (∂2u/∂x2) and μ (∂2u/∂z2) can be neglected for μ (∂2u/∂y2).

The series of Chadwick Memorial Lectures was started in 1956 by Harold Rogerson who gave a very complete picture of Roy Chadwick's life and experience as an aircraft designer. Since then lectures in this series have mainly concerned problems on future projects, which would certainly have excited his lively interest, rather than nostalgic reviews of the past.

However, when I was honoured by being asked to give the 14th Lecture of the series it occurred to me that nothing would be more appropriate than a paper on the History of the Vulcan, since it was not only a major Avro enterprise in its own right, but it was also the last project with which Roy Chadwick was intimately concerned. It had a peculiar fascination for him, because he had, all the time I knew him, an enthusiasm for the all-wing transport as the ultimate in aerodynamic and structural efficiency

The Two-Sting Rig system provides captive trajectory and grid survey testing in the ARA 2·74 m × 2·44 m transonic wind tunnel, on models of the order of 10% scale. The system has been in productive operation since 1979, having been used primarily in the captive trajectory mode to predict release characteristics for a wide range of stores/aircraft.

The paper describes the improvements to and developments of the system that have arisen from experiences gained during the last two years of its operational use. A brief description only is given of the general arrangement of the rig. Improvements to performance, simulation capabilities and to wind tunnel productivity are described together with current design studies for new applications.

An appraisal of the overall performance of the method against three other ground based techniques is used to illustrate its merits and defects, using results from recent Two-Sting Rig wind tunnel tests and flight.

As this is a wide subject area with many specialised fields, a broad review from a systems viewpoint would appear to serve the purposes of this Symposium best. Also, such a review may help to show that the importance of range instrumentation in upper atmosphere research is rather more fundamental and widespread than generally appreciated.

Stability criteria for systems governed by linear differential equations with constant coefficients are discussed in a general way. Detailed treatment of the sextic equation includes a simple and expeditious scheme for computing the test functions.

The heading of this lecture is the “Development of Air Transport During the War” but because time is limited I have had to exclude any mention of the ferry organisation which was responsible for the delivery by air of many thousands of aircraft. The work has however been, described in “The Atlantic Bridge.” The period with which I propose to deal is the 21 months ending in September, 1946. In this short period, in response to the demands of war, the Transport services of the Royal Air Force flew rather more passenger miles than did British Civil Aviation in the preceding 21 years up to the same date, and carried in addition great quantities of freight and military stores. This volume of transport flying, packed into a few short months, gave rise to many problems but also afforded unique opportunities for testing out new ideas and new equipment. My purpose tonight is to give a brief account of what was accomplished, and against this background to examine some of the lessons which were learned and the ideas for the future to which they gave rise.

The object of this talk is to give you a situation report on the Concorde flight test programme and to indicate the progress made to date.

Two aircraft have been engaged on the programme so far, the prototypes 001 and 002 (Fig. 1). The French base for Concorde flight test operations is at Toulouse and the British flight test base is at Fairford in Gloucestershire. The two prototypes will be joined in the flight test programme next year by the two pre-production aircraft, 01 and 02.

As is well-known, Concorde is a slender delta wing aircraft and it may be appropriate at this stage to state some of the considerations that led to the choice of this configuration. By virtue of a large root chord, the delta wing can overcome all the disadvantages of lack of structural stiffness and lack of wing volume associated with thin highly swept wings and yet remain aerodynamically thin.