Before reading this paper, I should like to make a brief explanation of my reason for changing the published title.

The original intention was to give a survey of civil flying boats in general, but after due consideration the subject appeared to me to cover far too much ground, unless it was restricted to merely a collection of already published data of past and present aircraft of this type.

Whilst a paper of this nature would, undoubtedly, prove to be of considerable interest, yet, personally, I feel more competent to review the three types of flying boats designed purely for civil use, which have come directly under my supervision during the past eight years.

The present paper is confined to matters concerned with the requirements for landing and take-off of aircraft at land aerodromes, that is to the landing area.

In the selection of sites the questions that arise are size and over-all gradients. In development of a selected site account must be taken of directions of landing, dimensions of flightways or runways, local gradients or undulations, nature of surface. Finally, to ensure safety of flight the site must be protected by zoning.

The subsequent problems of detailed layout, of civil engineering in construction, of control and equipment, and of design of administrative and terminal buildings, though susceptible of more popular treatment, come later in sequence. My first more detailed study is therefore devoted to what may be termed the aircraft's point of view as to what it would like in order to bring in and take out its load in the most economical manner.

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.

In Part V of my recent paper, when discussing and tabulating the conditions that obtain at low Reynolds numbers (more especially as concerns the dynamics of flight of the model depicted in Fig. 14), the data shown in Table IX and plotted in Fig. 15 need correction. It appears that in the tabulation an incorrect constant was taken. Furthermore, the distinction which exists at low Reynolds numbers between data secured in the wind channel, in which, generally speaking, wind velocity is constant, and the data relating to a glider in free flight in which W is constant, was not sufficiently explained.