The Basic Theory of the deflection of long, thin plates under normal pressure is extended to cover the effects of initial lateral tension or slackness in the plate and the effect of deformation of the supports at the edges of the plate under the lateral tension developed. The procedure is illustrated by application to a case of a plate under initial tension with its edges held apart elastically, and the computed values of the strains are compared with values measured experimentally. The application to an initially slack plate is also illustrated by a diagram.

Liaison between the engineering and computing sections of an aircraft company suffers when the engineer feels he is “losing control” of his own problems. This situation is typically due, not to distrust of the calculating engine, but to variance in the numerical methods favoured by the engineer and the engine programmer.

In both civil and military flying take-off and landing accidents represent a major part of all accidents. In both take-off and landing, the problems are becoming more acute with the current change to larger and faster aircraft, and even more significantly with the change to jet engines.

The majority of accidents occurring in these two phases of flight are attributed to “ human error,” or “ pilot's error of judgment,” but recent human engineering studies have shown that in many cases the real cause has been due to the engineering situation overloading the pilot in some way, or requiring him to make judgments based on insufficient information.

Before any aircraft type is granted a certificate of airworthiness its performance characteristics are accurately determined and, for large aircraft at least, scheduled in an approved flight manual. Superimposed on these data are certain basic performance criteria which usually limit the operational weight with altitude and temperature, and these limitations apply under all operating conditions.

In order to ensure a satisfactory level of safety for daily operation under varying conditions it is necessary to apply an operations code which takes into account other parameters such as :

(a) runway surface, gradient and length,

(b) obstructions in the take-off and landing flight paths,

(c) obstructions en route.

During the discussion the point was made by a speaker from the Industry that he had come to the meeting to learn; that many of the audience of 200 agreed with him was reflected in the discussion, for, of the 23 who participated 19 were from the research establishments and universities.