Knowledge of the motions of aircraft control surfaces due to oscillating hinge moments is of great importance for flutter investigations. While the impedance of the power control unit may play a large part in determining these motions, it is not their only cause. The elasticity of the power unit mounting and the effect on the input of distortion of the aircraft structure, an effect which may depend on air speed, may also be important. Nevertheless the influence of the power unit itself is of major importance. No very satisfactory methods appear to have been devised yet, however, for making such tests. The difficulty lies chiefly in applying the large oscillatory loads to the output of the power control unit, which are necessary if the test is to be realistic. The facts that the oscillating loads must be applied to the jack while it is moving, and that a non-oscillatory opposing load is also desirable, add to the difficulties. For convenience in assessing the characteristics of the unit, it is desirable that the oscillating load should be superimposed on a constant opposing load and that the basic jack motion should be of constant velocity.

The work described below deals, in detail, with the methods whereby the motion of an airship can be calculated. The possible motions of an airship are affected by such factors as its stability, motion of controls, release of hydrogen, dropping of ballast, engine power available, and gustiness of the air. The methods to be described are capable of dealing with these effects either separately or combined in any arbitrary proportions.

The pioneer rarely receives that meed of praise which is his due, until those days arrive when his pioneering has become a page or so of history. What meed of praise he may then receive is too often made savourless by critics unable to disassociate themselves from the knowledge of their own technical era. The halting speed of pioneering aerodynamic research cannot be judged by the supersonic speed of secret splittings of the atom.

It was R. L. Stevenson who said that to travel hopefully is a better thing than to arrive. In aviation we have arrived at that streamline flow of technical jargon which deludes so many they have at last reached the boundary layer of aeronautical knowledge, so that they find experiments with plates always a little flat, although their curiosity may still be aroused by flying saucers.

This paper describes some work, mainly of a theoretical nature, done at the Royal Aircraft Establishment, Farnborough, during the years 1946-1947. The immediate object of this work was to establish some general principles for the guidance of the Ministry of Civil Aviation Airfield Lighting Committee, which is the body charged with the task of deciding what visual aids shall be installed on the civil airports of this country. The work is far from completion and from the scientific point of view, this account of it must necessarily leave some loose ends, but it is felt that the method of attack and the underlying ideas may prove useful to other workers in this field. If this should prove to be the case, then international standardisation will have been brought a little nearer, and as will be made clear in this paper, this is almost as necessary for the visual aids as for the radio aids.

The advent of the jet transport age both for commercial and military aircraft will require conversion to jet training for pilots of all types of transport aircraft. This is the time therefore when consideration ought to be given to some comprehensive scheme on an Empire-wide basis for future recruitment and training of Pilots to a common standard.

It is not enough to assume that the needs of commercial aviation will be supplied by the Royal Air Force. There are two sound reasons why reliance on such a flow will prove erroneous. Firstly the training of the R.A.F. Transport and Bomber pilot is much akin to the requirement for the commercial airline, and once Air Forces have trained their long distance pilots they will make a career sufficiently attractive to induce the pilot to stay. Transport Command of the R.A.F. has already inaugurated such a scheme.