Seaplane tank testing is an offshoot of ship tank testing, the technique of which was founded by William Froude nearly 70 years ago and is now highly developed. Apart from the fact that a scale model is towed through still water, however, there is little in common between the two systems of test, though one link remains in spite of dissentient voices; Froude's laws are used as the basis of correlation between model and full scale. In other respects, the conditions of operation of a ship and a seaplane on the water are so different that when the R.A.E. tank was built, the whole existing technique was reviewed.

The MacRobertson Air Race, with its carefully thought out rules and conditions, has turned out to be one of the greatest incentives to the progress of aircraft design in the history of aviation. The fixing of the average distance between control points along the route of the race, together with the necessity for compliance with a British normal Certificate of Airworthiness, and the need for high speed all combined to make a problem for the aircraft designer the solution of which cannot but benefit very materially the advancement of aeroplane design.

Many long range records have been taken in the past, but never with an aircraft possessing a Certificate of Airworthiness. Many speed records have been taken, but few with an aeroplane which complies with Certificate of Airworthiness requirements. Here we had a contest which demanded of the aircraft the utmost range and speed consistent with the possession of a Certificate of Airworthiness.

Existing information on the aerodynamic characteristics of aircraft winter landing gear is very meagre and it was therefore desirable to test as many full size skis as possible in order to collect data concerning the various types of skis in actual use.

It was known that the air resistance of existing types is quite high and the experiments were intended to explore the possibilities of producing an improved type of ski having considerably lower air resistance.

The large pitching moments on present types of skis give rise to serious problems in trimming gear design, especially on high performance aircraft. The experiments aimed at producing a ski on which the pitching moments would be considerably reduced in order that the use of exterior trimming cables might be avoided.

The object of production is to give service to the user. The value of that service is generally measured by the results obtained (either by way of performance, ease of maintenance, reliability, long life, and appearance) against the cost; and given two similar products, by which I mean products designed to fulfil identical functions, the purchaser will prefer the one which gives him equivalent or greater service at the lesser cost.

In the early days of aviation in 1910 when Rolls, Egerton, Ogilvie and Grace were flying the open machines at the Aero Club's flying ground at Eastchurch, Grace made the interesting statement that in a few years aircraft design would develop under a continuous flow of invention in the same way as the motor car was then developing. Had Grace lived he would have been astonished at the truth of his prophecy, for the subject known at the Patent Office under the head of “Aeronautics“ has developed into one of the greatest industries in the world, and by the end of the year 1930 the abridgments on Aeronautics had become one of the stoutest volumes in the patent classification. In spite of this growth which marked out the subject for a department of its own, for some inscrutable reason the Patent Office then decided to mix up aircraft with ships and thenceforth have published these two subjects in a single group instead of keeping them separate as before that time.

The rapidly extending employment in many industries of cold pressing and stamping operations in the production from sheet metal of a great variety of components, embracing both simple and very complex shapes, renders cold pressing an extremely suitable subject at the present time for a joint discussion by a group of technical societies representing a wide range of industries. The particular interests of these industries naturally vary widely, both as regards type of production and the materials employed, but there should exist many basic problems common to all.

Simultaneous equations of three or more variables are notoriously trouble some to solve numerically and, moreover, are frequently sensitive for certain relative values of the variables. This usually precludes the use of the slide rule and in consequence resort has to be had to accurate working to an increasing number of decimal places involving much labour even with a calculating machine.

A method is here given which is applicable to certain classes of equations of frequent occurrence in mathematical physics and engineering science, which method is a combination of what is knovwi as the Iteration process and the means of applying this principle to end moment distribution devised by Professor Hardy Cross.

The Author endeavours to indicate briefly the growth of flying—boats from their inception to the present day and to forecast their probable line of development in the future. It is shown that our present achievement has been arrived at after the comparatively short period of twenty—five years and an attempt has been made to indicate the type of flying—boat which might normally be expected to mature within the next decade.

The water characteristics of a present—day hull are discussed and typical curves are included giving the resistance, attitude and the effect of applied moment for a flying—boat of approximately 40,000lb., all—up weight.

Before proceeding to a detailed investigation into a particular case of a flying—boat of the future, the Author briefly describes the progress which has been made with regard to the engines and compares the relative advantages of the compression—ignition engine and the petrol engine.Reasons are given why the petrol engine still tends to retain its supremacy.

For the future development the Author has taken the particular case of a flying—boat of 300,000lb. all—up weight and has attempted to analyse the probable structure weight of such an aircraft and what could reasonably be expected in the way of pay load and performance.The general conclusions are that the construction of such a boat would be possible, its structure weight by means of an increased wing loading could be maintained at the present—day figure and that its performance would materially increase.

Problems involving discontinuous aerodynamic twist, as for a flapped wing, are not readily soluble for wings having a rectangular plan form or straight taper. Lotz's method (B.Ae.S. Journal, May, 1934) has been stated to be particularly suitable, but a recent American report used in preference a direct method of successive approximation. In either case a fair amount of labour is involved, and the final results are only approximate. The exact solution for a wing of elliptic plan form, whilst no-t directly applicable to the usual type of tapered monoplane wing, is readily obtainable, and should give a good idea of the lift distribution and induced drag due to a flap on an actual wing.

For the calculation of the climbing speeds of aeroplanes several methods are in use, which, as is well known, do not yield quite accurate results when applied to machines with great climbing capacities, and give rise to inaccuracies which become of greater importance with increasing climbing capacity of the plane. The climbing speed, up to the present, has not been great in respect to the forward speed used when climbing, so that for the calculation of the climbing speeds the method fairly generally used and described in the “Handbook of Instructions for Airplane Designers, ”from the U.S. Army Air Service, could be used without serious objections. It has, however, been found desirable to look for a better method for calculating the climbing speeds, owing to increasing engine powers accompanied by decreasing drag coefficients of the aeroplanes, as well as to the introduction of variable pitch airscrews.

The process of cold pressing can only be applied to the more ductile metals, and the greater part of the material so treated is in the form of thin sheets. Leaving out of account such exceptional materials as lead, a ductile metal is appreciably hardened in the process, losing some of its ductility and having its “elastic limit” raised. It can be restored more or less completely by annealing, according to the temperature and the time of treatment. In addition, changes in ductility may occur in course of time, even at atmospheric temperatures.