The primary object of flying is movement over the surface of the earth in the shortest possible time, and thus it comes about that the performance of an aeroplane is that characteristic which commands greater attention than all others.

Even before 1939 the problems of high-speed flow were receiving a great deal of attention in the German aeronautical world. Their leading aerodynamicists, Prandtl, Busemann and Schlichting among others, had contributed largely to the theory of compressible fluid flow, and basic experimental research in the high-speed field had begun both at Aachen and at Göttingen. The activity in Germany in this particular field before the war was, in fact, much greater than in Britain, where Mr. Lock and his co-workers at the National Physical Laboratory carried practically the entire responsibility for such work.

The great increase in aircraft speeds during the war, and in particular the arrival of jet propulsion, completely changed our attitude to the subject in Britain. What had been an absorbing fundamental study became, quite suddenly, an important operational problem, looming large in every new fighter design.

The above meeting of the Royal Aeronautical Society was held in the rooms of the Royal Society of Arts, John Street, Adelphi, W.C.2., on Thursday, November 29th, 1928.

The President : 'The technical aspects of the production of aircraft were of considerable importance because, from whatever point of view one regarded aircraft, economical and rapid production were essential. Mr. Sigrist is a Director of the Hawker Engineering Co. He was associated with Mr. Sopwith as far back as 1910 and had been intimately connected with the affairs of the Sopwith Company—particularly the technical affairs relating to design and construction. He had been responsible for the design of one of the first British machines to win the Schneider Trophy. His wide experience would enable him lo speak with special authority on the technical aspects of the production of aircraft. The Society was particularly glad to welcome Mr. Sigrist as a lecturer for the first time before them.

The lecturer adopted the course of explaining the Cold Working of Metals from first stages.

The lecturer first dealt with the cold raising of metals and pointed out that in this case the operator always worked from the outside, and to avoid “ puckering ” of the metal it was gradually hammered concentrically so that “ puckers ” were eliminated almost as soon as they appeared.

The spinning of metals was then dealt with and nearly all cylindrical objects are worked in this way. Commencing as a metal disc the object is placed on a lathe and backed up on to a wooden former block and gradually formed on to the block. By eliminating the sudden bending of the metal round the sides of the block the “ puckers ” are reduced to a minimum and the metal is allowed to “ flow.”

When the all-metal cantilever monoplane brought to a close the era of wood, tubes and fabric for aeroplane structures, the new development opened up broad fields for the improvement of aerodynamic efficiency, with resulting great increases in all-around performance, military effectiveness, and economy of operation.

The all-metal fuselage represented a new type of construction in that the skin formed a shell to replace trusses in carrying the bending loads imposed at the tail in flight and on the ground.The scheme of using a shell to give–at once–structural strength and aerodynamic fairing, previously accomplished by two elements, appears to be economical and sound. If the labour now needed for the fabrication and assembly of the multiplicity of internal members is to be eliminated the stresses must be taken in the skin and the principle should, if practical considerations permit, be extended to include the wing and fixed tail units.