Mr. Foord: It has been truly said that “lubrication is the heart of an engine,” and I think this saying applies in the strongest possible sense to aircraft engines.

The reasons for this are manifold and one has only to consider the overall thermal efficiency, the low weight/power ratio and consequent minimum scantlings and bearing surfaces, and the high working temperatures of this class of prime mover compared with other types, to realise that the duty the lubricant has to perform is far and away more severe than is the general case.

If one takes into consideration all the various properties which the aircraft engine designer demands for the lubricant, it must be recognised that from an ideal point of view, there is no really satisfactory lubricant for the work and that the only thing that can be done in order to give the best all round results is to effect a compromise.

Major T. M. Barlow : All historical records of aviation from the earliest attempts at flight to our present-day Schneider Trophy and other record flights, show that in common with those nineteenth century experimenters our modern engine and aircraft designers are in one continuous struggle with the physical laws of weight. It is true that the early pioneers were faced with the problem of flying as such to the extent of carrying one man by a heavier than air machine a few hundred yards, but once this was achieved development quickly enlarged, the problem, and weight, with its relationship to power, lifting surface, safety factors, performance, range, and later—with the coming of civil transport—financial weight in the form of pay load, have become the all important item with the aeronautical engineer and constructor.

A system of external forces on the structure of a rigid airship can be analysed into two or more of the component systems due to

1. 1. W. The Weights of the members of the structure and the weights of the masses carried by it;

2. 2. L. The Lift and pressure of the gas;

3. 3. A. The Aerodynamic forces consequent on the relative motion of the airship and the air;

4. 4. T. The Thrusts of the airscrews;

5. 5. R. The Reactions due to either the mooring arrangements, the hauling-in guys, the supports used in the shed, or handling on the ground.

As these component systems, though restricted by their interdependence, are individually variable, a very large number of complete systems is represented by the possible combinations and variations that can occur. It becomes necessary, therefore, for the purposes of design, to attempt to limit the number of combinations to be considered, and to restrict the variations of the components, but in such a way that the structure designed to carry the resulting systems with adequate factors of safety, shall be able to carry any other possible system with an appropriate factor of safety.

Mr. Douglas : From very early days adhesives have played an important part in the joiners’ trade. The necessity for consistent high quality in glues and cements became acute when they were used under conditions of high stress in aircraft structures. It is natural, therefore, to find that aeronautical interests have been largely represented on research committees which have investigated the use of adhesives. At the end of 1919 the Adhesives Research Committee of the Department of Scientific and Industrial Research was formed to continue the work of the Adhesives Committee of the Conjoint Board of Scientific Societies. It was realised that one of the obstacles to the study of adhesives was the unsatisfactory nature of the tests which determine their strength in timber joints. Many properties of glue (such as viscosity, jelly strength, etc.) have been used to control variation during manufacture or as an indication of probable relative strengths in timber joints, but it has never been generallyadmitted that any simple property of the glue itself can be accepted as representative of the ability of that glue to effect a joint with timber. In the present state of our knowledge, therefore, it appears to be necessary to make final appeal to the timber glue test piece.

Unlike the motor-car engine, which is generally designed, built and tested in association with the vehicle which it eventually propels, the aero engine is often designed and built with little or no knowledge of the types of aircraft in which it will be employed. The remainder of the power plant, fuel, water and oil systems of the car are also designed at the same time and to suit the chassis, but the aero engine, in the various types of aircraft, is likely to be coupled to many different forms of these systems, and consequently numerous problems arise between the completion of the acceptance tests of an engine and the final approval of an aircraft power plant for flight tests.

It is now rather more than three years since I last had the honour of presenting a paper before this Society dealing with air-cooled aero engines. At that time the air-cooled engine had not fully won a place “in the sun,” which may be fairly stated to be the case to-day.

For some years after the war there was a considerable aversion towards the air-cooled aero engine owing to certain types which had been developed during the war which were supposedly air-cooled, but in reality obtained the greater portion of their cooling by means of exorbitant fuel and oil consumption. As lately as four years ago the practical advantages of the air-cooled engine were only tentatively appreciated by the aircraft constructor, and naturally, owing to his somewhat painful experiences in the past in respect of unreliability and high fuel consumption; it required some missionary work and proof in order to persuade him that the new family of air-cooled engines would really perform in the way their designers claimed for them.

This was a joint meeting of the Royal Aeronautical Society and the Institution of Automobile Engineers, and was held in the Lecture Hall of the Royal Society of Arts, John Street, Adelphi, W.C.2, on Thursday, November 8th, 1928.

The President : He extended a hearty welcome to all present and particularly to the new President of the Institution of Automobile Engineers (Mr. L. H. Hounsfield), whom he hoped would attend many future meetings of the Society as well as the joint meetings which had been arranged. The joint meetings had been very successful indeed in the past and he hoped that, in addition to those which had already been arranged for the present session, there would be many others in future sessions.

Ever since I first began to study Aeronautics I have been annoyed by the vast gap which has existed between the power actually expended on mechanical flight and the power ultimately necessary for flight in a correctly shaped aeroplane. Every year, during my summer holiday, this annoyance is aggravated by contemplating the effortless flight of the sea birds and the correlated phenomenon of the beauty and grace of their forms.