Before beginning my lecture, I should like to say that it gives me particular pleasure to be able to take part, as a guest, in this meeting of the Royal Aeronautical Society. So much important progress in the development of aeronautics has had its origin within the circle of the Royal Aeronautical Society, the oldest society of its kind in the world, and so many successes in the scientific and practical spheres are coupled with the names of its members that all the staff of the D.V.L. regard as a particular honour the friendly interest in our work, expressed by your invitation.

It is indeed an honour to appear before you to address you on the subject “American Methods of Aircraft Production.” We in America have long held the Royal Aeronautical Society in high regard, amply justified by the excellence of its published papers and the example it has set in organisation and in the conducting of an aeronautical society. Indeed, a few years ago when several of us in America decided that we too should have an aeronautical society, we planned our own organisation very largely on yours. We are very much pleased that the relationship which has existed between your Society and the Institute of the Aeronautical Sciences in America throughout the brief career of the latter has been so close and friendly and I can assure you that we intend to do everything possible on our part to continue this highly desirable condition.

The primary object of flying is movement over the surface of the earth in the shortest possible time, and thus it comes about that the performance of an aeroplane is that characteristic which commands greater attention than all others.

The subject which I have to discuss to-day is one which can be treated from a standpoint of the scientist or from that of the practical engineer. I am going to try to discuss it from the latter point of view.

The testing of the behaviour of aeroplanes in flight, to which I want to draw attention, does not deal with research on stability and control, it only deals with checking the flying characteristics with regard to the requirements which should be fulfilled.

In the Dutch requirements for a certificate of airworthiness for civil aircraft there are several detail rules, which all tend to state that the aeroplane should be stable and well controllable within the whole region of flight, and for all conditions which may occur in normal and special use.

The development in recent years of trans-oceanic flying has raised new problems, both in regard to the design of aircraft of increased range and performance and the operational and technical questions involved, and also from the point of view of the ancillary services—radio and meteorology—on which the successful operation of an air route must, ultimately, depend.

The importance of an organised meteorological service as an adjunct to the safe, regular and economical operation of an air route has been recognised from the earliest days of civil aviation. Meteorology, however, must play an even greater part in the operation of long trans-oceanic routes than in the case of the shorter routes such as those which form a network over Europe.

It may be said that the title of this paper covers too wide a scope to be dealt with satisfactorily in the time available and that as a consequence the treatment of each section will be of a sketchy nature.

This is undoubtedly a justifiable criticism, particularly from the point of view of a specialist, but the aim has been to present what it is hoped will be helpful information of a practical nature to builders of aircraft rather than aero engines. There is no intention to enter deeply into the technical aspects of the applications of aluminium and its alloys to aircraft, but rather to review some of the many problems and enquiries which have been encountered during several years' contact with the aircraft industry.

My first reaction to being asked to speak on this subject was that it is the user and not the producer of model data whose views we want to hear, and I am glad to say that Mr. Ellis has agreed to co-ordinate with me, so that I have some inside knowledge to draw on, if I venture to say what a designer does.

I wish in the main, however, to take the title in rather a different way, and to discuss in what sense model tests can be expected to give results useful to the designer.

Before embarking upon the business of this paper I should like to make one or two general remarks by way of explanation.

It was suggested by two members of the Council that the present situation with regard to ancillary power services on aircraft was far from satisfactory, and that the question might well form the basis of a lecture before the Society; moreover, that such a lecture might be more interesting and valuable if presented as a joint paper by a member of an engine firm and an aircraft firm respectively. Mr. Nixon and myself have had the honour of being asked to collaborate in this connection and we trust the result will be acceptable to you.

When the writer undertook the preparation of this paper, he rapidly discovered that it was not easy to find any branch of the subject which had not already been dealt with exhaustively by far abler pens than his. One or two matters have, however, been chosen about which information is somewhat meagre or scattered, and which may not, perhaps, be familiar to the aircraft engineer.

First a review will be made of the various types of electronic engine indicator which have been developed up to the present time; this instrument is coming into prominence now, and although it has by no means reached a state of perfection, it is a valuable asset in the hands of the research engineer for the study of fuel problems and other minor points.

The subject of the carburettor as opposed t o fuel injection is one which has created much controversy in aero engine design and development. Current opinions both in this country and abroad are many and varied and it would be presumptuous to forecast which will eventually predominate. The object of this paper is to present an unbiased review in the hope of provoking a useful interchange of opinions and experiences.

It might be argued that claims for one system can be countered by claims for the other and to be impartial it is necessary, therefore, to be familiar with as many facts and as much published information as possible. Owing to the meagre amount of information available on fuel injection, the paper is not as complete a review as the authors would wish, but it is hoped that sufficient material has been presented to be helpful to those who are interested in the subject.

It is well known that, under certain conditions, duralumin and other wrought aluminium alloys are liable to suffer intercrystalline attack, such corrosion being frequently accompanied by little visible corrosion product on the surface of the material. The necessity for careful temperature control during the solution heat treatment of duralumin and the beneficial influence of a rapid rate of cooling after such heat treatment on the corrosion-resistance of this material are now too widely appreciated to need emphasis here.

Aerodynamics is one of the main fields of application for practical mathematics and the treatment of aerodynamic problems requires a thorough mathematical training. Whoever opens a modern book on aerodynamics will be surprised from the very beginning, that the phenomena within this very fugitive medium air may be expressed by formulas according to mathematical laws.

We must, however, never forget, that before a flow phenomenon can be mathematically analysed, physical reality must be understood by observation and experiment.

The mathematical treatment will always tend towards an approximate solution, as it is much too complicated to analyse a flow process exactly.