It is almost four years since a series of papers on Naval Aviation was presented to the Royal Aeronautical Society in the full day session held on 7th May 1947. The first paper in that series, “Technical Problems of the Design of Naval Aircraft,” read by W. S. Farren, stated the fundamental problems clearly.

During the intervening years, the general trends in aerodynamic and power plant development have been reflected in the design of carrier-borne aircraft and are beginning to stabilise into a recognisable pattern. Thus, turbo jet and turbo-propeller engines are now accepted for Service use, there has been general aerodynamic improvement including the suppression of drag arising from the carriage of stores, and it is normal to find that prototypes are mounted on a nose-wheel type undercarriage.

Perhaps I had better begin my story by giving you a very brief resume of my flight outwards to Cape Town. The flight was made possible by the very enterprising support of the Argus South African Newspapers, who purchased the Moth for me. When the flight was completed the machine was given to me ; hence the possibility of my returning, in a purely private sense, as I have done this year.

A general method of solution for rectangular plates with clamped edges and any kind of loading has been developed by Professor S. P. Timoshenko. The present paper gives the results of calculations using this method for the maximum deflection, moment, and edge shears for rectangular plates of various proportions with all four edges clamped and loaded by a single concentrated load at the centre. Similar data for a clamped rectangular plate with a uniformly distributed load have been given by I. A. Wojtaszak and also T. H. Evans. A report of an experimental investigation of this problem with some analytical results has been given by R. G. Sturm and R. L. Moore.

The application of strain energy or slope-deflection methods in the analysis of redundant structures leads to a number of simultaneous linear equations with numerical coefficients; the equations may be obtained in such order that each successive equation contains one new unknown, until all the unknowns are so included. This is the only condition essential for the method to be described in the present paper, but the labour is much reduced in slope-deflection and strain energy applications by the fact that most (or all) of the equations contain very few of the unknowns. The method to be given reduces the solving of these equations to a column of successive evaluations, followed by the solution, by algebraic methods, of a small number of simultaneous equations; and a final column of evaluations. In the remaining paragraphs a number of problems are examined to show how the equations may be obtained in suitable sequence for the method to apply. Following an application to the determination of secondary stresses, the operations involved in the moment-distribution method and in this method are compared. A numerical example is worked out in the simple case of §2, and it is shown how any order of mathematical accuracy in the roots may be ensured, provided that sufficient figures have been retained to permit that accuracy.

Existing methods of estimating the blade loadings on a helicopter rotor in forward flight have suffered from the necessity of using false simplifying assumptions in order to make possible an analytical approach. The following list gives the most usual of these assumptions:

1. (i) Blades have no twist or taper, or are twisted and tapered in a particular way.

2. (ii) The coning angle is small enough to neglect the resulting changes in velocities, angles, and so on.

3. (iii) The disc is horizontal.

4. (iv) The components of velocity parallel to the blade length may be neglected, and forces are calculated for and act with reference to the velocities normal to the blade length.

5. (v) There is no variation in downwash over the disc, or the variation is capable of simple expression.

6. (vi) The blades extend from hub, and tip losses are neglected.

7. (vii) The blades have pure flapping hinges and the analogy between flapping and feathering enables loadings calculated for flapping blades to be referred to a “hingeless” rotor system.

The 822nd Lecture to be read before the Royal Aeronautical Society, “Progress Towards Hydraulic Serviceability,” was given by R. H. Bound, F.R.Ae.S., and H. G. Conway, F.R.Ae.S., on 15th March 1951 at the Institution of Civil Engineers, Great George Street, S.W.I. Major G. P. Bulman, C.B.E., F.R.Ae.S., President of the Society, presided at the meeting and introduced the lecturers, Mr. R. H. Bound, Technical Director of Dowty Equipment Ltd., and Mr. H. G. Conway, Technical Director of British Messier Ltd.

To be asked to prepare a paper for delivery to the Royal Aeronautical Society on the subject of the serviceability of a product with whose design the authors are closely associated, offers an excellent opportunity for a critical survey of the field, uninfluenced by commercial considerations and with the realisation that the admission of faults, where present, is essential for constructive consideration of the whole problem.

The hydraulic installation of an aircraft is now such an important and integral item of equipment that any steps which may be taken towards improved performance in serviceability would contribute notably to the operational success of transport and military aircraft. The degree of complexity required in modern aircraft hydraulic systems is such as to make impossible a completely fool-proof system. But consideration of factors which keep trouble within very small bounds is of vital importance.

Propeller theory has always been a subject of extreme difficulty, and those who riginated the screw propeller as a means of propulsion and developed itduring the latter half of last century were in most part guided by common senseand empiricism. Without much in the way of theory to guide them the results thus achieved in connection with marine propulsion were remarkable—but little short of the best possible. The designers of the early experimental aircraft were able to make use of the wealth of experience thus placed at their disposal; nevertheless, some new aspects of the problem presented themselves—fortunately the vortex theory, newly developed to deal with the problem of sustentation in flight came to their aid, though the manner of its application was not obvious or easy. The writer's first attempt consisted in treating the propeller blade as an aerofoil connected to the boss by an arm of spar section, geometrically related to a helical surface, in which the tracks of the blades relatively to the fluid follow these surfaces.

The great interest being taken at present in the use of aeroplanes in connection with mining, shown in the reception given to a recent paper before the Institution, has suggested to the author that a paper may be welcomed which deals with aerial survey as an aid to the geologist and to the prospector, and which attempts to put before members information on the subject, much of which is available but not altogether accessible.