During the past few years an extensive amount of experimental data on split flaps has been made available to the aircraft industry, through the publications of aeronautical research laboratories, both in this country and abroad. In general, each publication deals with one particular aspect of the problem, and when the effect of wing flaps on the performance of an aircraft is being estimated a certain amount of difficulty may be experienced in deciding which of the many reports available gives results most readily applicable to the case being considered ; and what allowances, if any, should be made for wing taper, flap cut-out, fuselage, etc.

In this report the available data has been analysed with a view to answering these questions, and presented in such a form that it may be readily applied to determine the most probable change in the aerodynamic characteristics of a wing that may be expected from the use of this type of flap.

From the appendix an estimate of the accuracy of the method can be obtained, as a comparison with full-scale data is given for lift and drag, and for the other flap characteristics the original curves have been reproduced.

A recent paper gave an elementary analysis of the effect of control procedures on the flow of air traffic. It was shown that the average delay experienced by aircraft landing at an airport increases rapidly as the arrival rate approaches the maximum handling capacity of the airport. It is the object of the present paper to give a more rigorous treatment of the problem and to derive the distribution of delays under different traffic conditions.

The maximum handling capacity of an airport is the greatest rate at which aircraft can enter the airport with absolute safety. It is determined by the safe minimum separation between successive landings. An aircraft arriving in the central zone with less than the safe minimum separation is withheld from landing until the minimum interval has elapsed.

In the following it is generally assumed that aircraft cross the boundaries of the control zone from random directions with random separations, the mean arrival rate being constant. Aircraft which follow their predecessors too closely are assumed to be delayed for a minimum period so that none lands with an interval less than the safe minimum. As a simplification it is assumed that no aircraft takes off from the airport.

Designers and technicians pay a great deal of attention to the development of jointing methods for use in the construction of aircraft. A satisfactory method should be neat, economical in labour, flexible in application, and capable of yielding consistent results with a low weight penalty.

Electrical resistance welding meets the above requirements and it is with this process that I shall deal.

Complicated oscillatory systems may be broken down into component “ sub-systems ” for the purpose of vibration analysis. These will generally submit more readily to analytical treatment. After an introduction to the concept of receptance, the principles underlying this form of analysis are reviewed.

The dynamical properties of simple systems (in the form of their receptances) may be tabulated. By this means the properties of a complicated system may be found by first analysing it into convenient sub-systems and then extracting the properties of the latter from a suitable table. A catalogue of this sort is given for the particular case of conservative torsional systems with finite freedom.

The properties of the composite system which may be readily found in this way are (i) its receptances and (ii) its frequency equation. Tables are given of expressions for these in terms of the receptances of the component sub-systems. All of the tables may easily be extended. The tabulated receptances may also be used for determining relative displacements during free vibration in any principal mode.

A method of presenting information on the vibration characteristics of machinery, which is effectively due to Carter, is illustrated by means of an example. More general adoption by manufacturers of this method (which requires no more computational effort than must normally be made) would lead to enormous savings of labour in calculating natural frequencies of composite systems.

The lecturer has been concerned with commercial air survey operations since their inception after the war, more on the organisation, finance and business side, rather than on the technical. It is therefore from the angle seen from the directing side that this paper is submitted. As certain technical aspects will be of interest to the Institution, they are referred to, in order that attention may be drawn to them. Through the courtesy of the firms responsible for manufacture, certain apparatus is exhibited which includes an air camera, the automatic pilot, and the contouring stereoscope. Certain technical experts have kindly promised to be available to answer questions or to demonstrate apparatus, and certain individuals and firms have been good enough to lend photographs and slides. Acknowledgment for such assistance will be made in the reply to the discussion.

The slender–body solution for the flow about low aspect–ratio wings of non–zero thickness yields a pressure distribution which is valid in the vicinity of the leading edge and therefore suitable for comparison with measured distributions. In this note an expression is derived for the theoretical pressure distribution, due to small incidence, on a slender elliptic half–cone in uniform motion. It is shown that this distribution is additive to the zero incidence pressure distribution. A comparison with some low speed measurements shows qualitative agreement.

The method can be simply extended to other bodies of elliptic cross section.