I realise that many readers of this paper know more about private flying than I do; on the other hand, many may not be so experienced or have even flown. I have tried to put in things of interest to both and hope I shall be forgiven if I have put in too much elementary detail, or that my simple suggestions appear childish. I find that often it is the small and simple things which go to make for safety, comfort, and efficiency. I have no technical knowledge other than that gained by sitting behind internal combustion engines, which I have done during a great part of the last twenty years.

The loss in efficiency which arises in connection with present aircraft designs has been dealt with very fully during recent years. It has been shown that the perfect streamline aeroplane would only have a drag of one-third that of a conventional machine. While it is improbable that this ideal design will ever be attained, considerable improvements can be made by refinements in design and careful revision of those items which are the cause of comparatively big losses.

Many attempts are being made to reduce parasitic drag and interference effects, for the importance of obtaining increased performance by aerodynamic cleanliness rather than by increased power is apparent.

Referring more particularly to the undercarriage component, it can be fairly stated that until quite recently the aeronautical engineer has been more concerned with the provision of a satisfactory undercarriage mechanism than the more difficult problem of providing a low resistance unit.

The lecturer opened with a brief and general description of R. 100, which has an overall length of 709 ft. and a diameter of 133 ft., with a cubic capacity of 5,250,000 cu. ft. There are three power cars, each with two engines. These cars are situated at a considerable distance fore and aft from the passenger accommodation, and there was therefore a minimum of noise and vibration in the latter. The ship contained some 11 miles of special spiral seam tubing. Her displacement was 156 tons. In the Graf Zeppelin the cross sectional area of the girders equalled some 12 sq. ins., whereas in the British ship the cross sectional area amounted to 3 sq. ft.

The field covered by the title of this paper is a very comprehensive one, and is too large to be dealt with in a single lecture. Only certain aspects of the subject, therefore, will be dealt with, and very brief reference made to such tests as have been described in other papers.

The subject naturally falls into three divisions:—Ground tests, tests on the water, and aerial tests, and it will be convenient to deal with them in this order. The methods of test described are those in use at the Marine Aircraft Experimental Establishment, Felixstowe, the official seaplane testing station, and, as far as is known, these methods are as up to date as those in use in other countries.

If it is felt that gaps exist on which information is desired, the inquirer is referred to Squadron Leader England's lecture on “ The Practical Side of Performance Testing of Aircraft,” which was published in the Aeronautical Society's Journal of January 1928, and to other papers which are mentioned.

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.”

The trade was only just emerging from the stage when aero wheel brakes were merely adapted forms of automobile wheel brakes, and the aeroplane industry from the point of view of wheel brakes is now in about the same stage as the motor industry was with car brakes six years ago. In this respect the United States is very far ahead of us.

The aircraft industry is now realising, however, that the brake needs of an aeroplane have to be specially catered for, and it is to this end that research is being made, the ordinary motor car two-shoe brake being abandoned as inefficient.

The lecturer stated that the average reduction in the landing run of machines fitted with the modern Bendix-Perrot brake was 50 per cent., and that the fitting of brakes has the effect of assisting Ground Crew.

The first requirement in any manufacturing process is to secure a stable raw material, and to this end scientific control was essential, for it was found that the rubber obtained from trees on the top of a hill differed from the trees in the same field or plantation at the base of the hill. A process of blending was therefore essential.

The pure rubber was rolled and crushed so that it became a “ flannelly ” sheet of crêpe rubber such as is used on tennis shoes, etc., but in this form the rubber becomes sticky when heated. Filling agents are therefore added, and colouring materials to give the red tint for inner tubes and grey for outer covers.