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I have chosen for my address the subject of Co-ordination of Aeronautical Research in the British Commonwealth, not only because this is a very important and vital matter, but because at this time there are being held in Melbourne meetings between aeronautical research workers from Australia, New Zealand, South Africa and the United Kingdom in certain fields of research. Simultaneously, in Canada similar meetings are being held between aeronautical research workers from Canada, United Kingdom and Australia.
Aeronautical research, like human flight, is of comparatively recent origin as far as serious work is concerned. In Australia we can be proud to have had one of the pioneers—Lawrence Hargreaves—while the Wright Brothers based the design of their aircraft on experiments with aerofoils carried out in a wind tunnel of their own design.
A procedure was discussed in Ref. 1 for dealing with structural discontinuities by making the strain energy of the structure a minimum, subject to the conditions that the members to be cut out are entirely free from load, and the proof was based on the well-known method of Lagrangian Multipliers. Here is another proof.
The main factors determining the shape of a supersonic aeroplane or missile are aerodynamic in origin. However, as always, a compromise with structural considerations must be achieved, zero wing thickness for supersonic aircraft being just as unattainable as infinite aspect ratio for subsonic ones.
This compromise is more far-reaching in the supersonic aircraft because of the much greater importance of aeroelasticity.
In addition, there are entirely new problems which arise from the high structural temperatures attained in supersonic flight.
The growing demand for aerodynamically advantageous forms, for smooth surfaces, and last but not least for a better ratio of useful cross section to total cross section of fuselages lead to an increasing application of monocoque structures in aircraft construction. Unlike ordinary beams the behaviour of such thin walled structures under loads and their ultimate failure is influenced a great deal by instability phenomena. In the present paper these problems are dealt with in some detail for the case of pure bending.