An account that is to be of any value of a subject in such an early stage of development as the use of synthetic resin materials in aircraft construction, must necessarily contain a great many first thoughts and rough guesses, and anyone writing such an account must be prepared to take the risk of having to eat his words at a later date. But I believe it is better to have blundered than never to have thought at all, and it is my hope that what I have to say will at least arouse interest enough among those with special knowledge to contribute to the discussion at the end of the lecture.

In these days of long distance flights across large stretches of ocean aeroplanes will make considerable use of radio direction-finding apparatus, enabling them to keep their course on to a transmitting station at their goal. Over the Atlantic, for example, a series of beacons all the way across would be quite impracticable. The following is an analysis of the course flown by an aeroplane under these circumstances, showing also the increase in flying time over that on a compass course, and also the maximum deviation from the compass course.

The main reasons why trouble due to ice formation on aircraft was not experienced so much in the earlier days of flying as now were two-fold, (a) The greatly restricted amount of flying done during the winter and (b) the absence of means whereby flight in cloud for any considerable length of time was possible.

The degree to which ice forms, however, differs widely. Since much depends on the relative speed of the aircraft, free balloons are practically excluded. In the worst case ice cannot form on such aircraft to the extent to which heavy glazed frost is observed on the ground, unless the balloon pilot is a very bad navigator and remains in the danger zone longer than would be required for the ground surface to be coated with glazed frost.

The object of this note is to draw attention to a few facts which, taken together, suggest that, from a purely aerodynamic point of view, the difficulties involved in flight by human power may not be as great as is generally supposed.

Some years ago, in a lecture delivered to the Royal Aeronautical Society, the German soaring pilot, Lippisch, referred to an account of dynamic soaring given by Lanchester in his “ Aerodonetics ” and to some wind tunnel experiments made in Vienna.