The design of an aeroplane to achieve the greatest possible altitude is, from one aspect at least, a simple matter, because it is a case free largely from the compromises usually necessitated in the endeavour to meet best the operational requirements of a specification.

The starting off point must be the engine. I do not propose to touch the engine side of the problem, other than to regard the engine as an “ embodiment loan ” which has been made to the aeroplane designer and for which he has then to design an. aeroplane which shall achieve the greatest possible altitude when powered by this engine. Obviously, the main requirement from the engine is that it shall give the greatest possible b.h.p. per pound of its weight at very high altitudes. This means, of course, the highest possible supercharging and rather indicates the air-cooled radial engine because of the inherent low weight per b.h.p. of this type.

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.

This note shows how a pure resistance analogue can be used to find the lift on low aspect ratio wings travelling, with small incidence, at speeds close to the sonic velocity.

The method is applicable to flat, twisted or cambered wings and is simple in operation; the results obtained being in close agreement with those obtained by calculations based on the same theory.

The solutions given in this note are essentially those corresponding to the Jones theory, which is applicable to low aspect ratio wings at small incidence, travelling with velocity close to the sonic value. Under these conditions it has been shown that the three-dimensional problem reduces to a series of two-dimensional problems in planes perpendicular to the direction of motion. Thus the wing can be considered as a series of spanwise sections, the solution for each section, in terms of the velocity potential, being considered in turn.

It has long been the practice in engineering to use direct manual operation of the controlling parts of a machine, so long as it was within the strength of the operator, and so long as design of the operating gear was relatively simple. In innumerable applications, however, the increased demands for power by the controls, and the need for greater accuracy, have necessitated the development of servo mechanisms to drive them; that is, we have to sever, partially or completely, the direct mechanical link from operator to control, and use the inserted backlash, elasticity, and so forth, to meter power from an external power source.

In the flying control field we have come at this time to the transition stage, in that we have realised that, for a large number of applications, direct manual operation is impractical, and we are feeling our way towards suitable forms of servo controls for our various needs.

This method has been designed to give all necessary performance data, concerned with the take-off and landing of aircraft, in a cheap and efficient manner. The complete path of the machine from the start of the take-off run to beyond the screen is recorded on a single photograph and from it the reduction of the data is done readily and simply. In the case of a take-off the data obtainable is as follows :

1. (a) Take-off run.

2. (b) Nature and length of the transition.

3. (c) Height at any screen.

4. (d) Distance, velocity and acceleration at any point from the start.

5. (e) Angle of climb.

6. (f) Rate of climb.

7. (g) Any irregularities in the flight path.

Similar data can be obtained in the case of a landing. Any information may be extracted independently and the photographic negative filed for future reference.

The camera used is simple and inexpensive, both in construction and subsequent use. Four persons at present form the total ground staff and with an improved camera now under construction one of these is eliminated.

The accuracy obtainable with the present apparatus is sufficient to fix the position of the aircraft to within ± 2 feet. Once the initial work has been carried out on any aerodrome, future use of this method has been found to be simple, quick and sufficiently accurate for all normal requirements.