It is of cardinal importance that the facts of aeronautical history should be placed on record.

The stirring stories of these tremendous first fifty flying years must be told where and when and how they can, but should be told quickly before the mists of time and memory lose them for ever.

Here is set down the story of the unprecedented achievement of the Wright Brothers, their impacts on, and relationships with, those members of the one-time Aeronautical Society of Great Britain who knew them and were aware of the reality of their genius. It is a story of some importance and one which it is fitting should be on record in the Society's own publication, for all to read who may. It is told by the brothers themselves, and by members of the Society.

In Rocketry, the definition of Specific Impulse is given variously as Thrust per unit mass of propellants consumed per second and Thrust per unit weight of propellants consumed per second. The second definition is convenient in giving units in seconds, but is unsatisfactory in that the weight of a given mass of propellants depends upon gravitational attraction, and decreases with altitude.

Pressure Distribution and liquid-film tests on a 10 per cent, thick aerofoil revealed the presence of separation “bubbles” close to the leading edge. These bubbles are formed beneath the boundary layer which separates near the leading edge and re-attaches farther aft; their existence is usually indicated by localised constant-pressure regions in the pressure distributions. It is also believed that if a thin film of liquid (such as a suspension of lamp-black in paraffin) is spread on the surface, the scrubbing action of the air rotating in the bubble will tend to draw liquid forward into the bubble, and hence the location and extent of the bubble may be indicated approximately by the accumulation of the fluid.

Many boundary layer traverses of bubbles on N.A.C.A. aerofoils have been made, but it was felt that similar measurements of the bubbles on this particular aerofoil would provide useful data, since the separation characteristics of this section appeared to differ from those in the N.A.C.A. tests.

In A. H. Stratford's interesting note in the August Journal, he assumes that an airline is presented with an aircraft of given performance, and must decide what is the best range for it to fly. Surely the practical case is the exact opposite: that an operator wishes to carry passengers or freight between two given points, and must choose between perhaps three or four available types of aircraft. Moreover, it is up to the operator to tell the manufacturers which feature he wants improved (e.g. fuel consumption, take-off distance, and so on), when he is ready to order replacements.

Secondly, Mr. Stratford wishes to replace the usual concept of direct operating cost per payload ton mile by that of per cent, profit, as a measure of the efficiency of operation over a certain route. While this may be a more realistic approach to the problem of a private airline company, operating over a single route, its merit is not so obvious for the large national or subsidised airlines, which are often required to fly unprofitable routes.