The work which forms the subject matter of this paper relates to a device for reducing the air resistance of an air-cooled radial engine. It can be added to the engine without completely enclosing the cylinders, either singly or collectively, in streamline casings of the conventional type, which usually render the engine inaccessible.

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.

The contraction of a wind tunnel should be free from adverse pressure gradients, since this might cause boundary layer separation.

A wall contour has been designed for a circular cross-section contraction using incompressible flow theory. This gave a favourable pressure gradient at the beginning of the contraction where separation is likely to occur.

Appendix I compares the theory with experimental results obtained from a model of a proposed supersonic tunnel of which the contraction is rectangular in cross-section and which has been based on the results obtained in this report.

An ultra-wideband (UWB) log-periodic dipole array (LPDA) antenna inkjet-printed on a 0.5 mm thick photo paper substrate is presented. The overall size of the LPDA antenna is 130 × 60 mm2. The LPDA antenna exhibits stable input-impedance characteristics and a consistent end-fire radiation pattern over the whole operating band of 2.2–11 GHz. Fulfilling the need of high-gain flexible antennas for UWB, a highly directive measured gain of 9.5 dBi on a paper substrate makes it an excellent candidate for flexible wireless devices.

The object of the present paper is to draw attention to some of the recent researches which have had as object the improvement of the aerodynamic characteristics of aircraft. Such characteristics can be classified into two groups; those concerned with performance and those concerned with stability and control. In the former group come all those researches which aim at the reduction of drag, while in the latter group come those directed to the attainment of satisfactory stability and control in normal flight, as well as those concerned with the behaviour of auxiliary devices such as flaps and slots which are used under special conditions and in particular during landing and taking-off. The problems associated with flutter also belong to this group. The two groups may be broadly characterised by the words economy and safety.

The laws of reflection of pressure waves at temperature discontinuities are well known. Of particular interest is the effect of temperature discontinuities on the pressure conditions in the exhaust pipes and cylinders of two-stroke cycle engines, both models and running engines. Model experiments are usually performed at low temperatures with the cylinder release temperature and exhaust pipe temperatures of the same order; under these conditions the reverse type of temperature phenomenon occurs to that in running engines with excess scavenge air. In the case of a model during the exhaust blowdown the gas from the cylinder reaches the exhaust pipe with a greater density than that of the gas initially in the exhaust pipe.

I consider it a great privilege to have been chosen to give the first Rex Pierson Memorial Lecture, as not only is he an outstanding figure in British Aviation, but he was also one of my close friends.

Reginald Kirshaw Pierson was born in February 1891 at Fransham, Norfolk, his father being the rector there. He was educated at Felsted School. On leaving he was destined to enter the Bank of England, but at the last moment, mainly due to the untiring efforts of his mother, he was allowed to follow his natural bent, and take up engineering instead.

In 1908, therefore, at the age of 17 he entered the Erith Works of Vickers Ltd., as an engineering pupil-apprentice, passing through the various departments and, while there, taking his Bachelor of Science Engineering degree the hard way, from evening classes.

Major Green in his paper has given prominence to a subject which is now becoming of wide interest and great commercial importance. A method of assessing the economic value of speed is very desirable and Major Green has attempted to do this by means of an index figure.

I would like to put forward a method which, whilst it does not provide a datum or index figure, offers a ready method of comparing two or more machines, taking into account those features of the aircraft which are of economic importance. It must be accepted that the geographical and political features of different routes, time-tables, and other such extra-to-aircraft items could be included in any method of comparison without the use of an empiric formula, the relative importance of whose terms would be largely a matter of opinion. Further, this method is based not on subsidy earning but profit earning capacity.

It is shown that, on the basis of the data provided by two sets of influence coefficients for a wing (or other surface)–an “elastic” set giving deflections (and hence incidence angles) in terms of applied loads, and an aerodynamic set giving aerodynamic loads in terms of incidence angles (or other linear function of the displacements)–all “static” aeroelastic problems can easily and expeditiously be solved by the use of a digital computer. It is also suggested that the same method of approach may well be used for solving oscillatory aeroelastic problems such as flutter.

Compared with the general advance of aeronautics in the past decade, or indeed with sailplane development in the 20's and 30's, progress in sailplane design has recently been very leisurely. This is due in part to the fact that there is less scope and partly because little effort has been expended. The most important advances in the art have been in the understanding and use of meteorological conditions which make soaring flight possible; sailplanes good enough for the purpose have existed.

Before the Second World War the main design impetus came from Germany and Poland and in most current designs the German influence is still strongly evident. Since the war there have been outbreaks of activity in Switzerland (W.L.M.I., Moswey), Canada (where Shenstone and Czerwinski have inspired designs at Toronto) and in the United States. The total effort has not added up to that in pre-war Germany.

During the last few years continuous indicating electric exhaust gas analysers have been coming into use more and more for controlling the strength of the fuel/air mixture which the carburettor feeds into the engine.

These instruments have already been described in a publication (vide List of References (i)), but since they are of growing interest, especially for aviation, some further research as to their merits and shortcomings seems to be indicated.

Therefore tests have been run with an aircraft type of instrument (the “ Cambridge (N.Y.) Aero Mixture Indicator ”) and an automobile type of instrument (the “ Lantz Phelps Motor Fuel Combustion Tester ” ).

There has been considerable activity of recent years, particularly in America, in the field of integral structures for aircraft.

The fundamental problem in aircraft structures is to make a relatively thin skin covering take applied compression, shear and bending loads. This has been achieved so far by the attachment of stiffeners, but this requires a large amount of riveting which in itself causes structural inefficiency and also spoils the smoothness of the skin, particularly when laminar flow is desired. Metal gluing shows great advantages over riveting in this respect but it is doubtful whether the bond strength will be great enough to attach very heavy stringers to very thick sheet. Where structural loadings become higher the required thickness of sheet and stringers may make the continued use of riveting difficult, if not impossible.

With the present-day normal type of wing the spars are the principal members, and I propose to start by tracing very briefly the evolution of the spars which are used in the Wapiti wings to-day.

The personnel of the Steel Wing Company have been designing and making spars ever since 1912. I shall start from the time when we first began to use what might be described as the box type of spar, which was composed of four strip steel sections.

The first spar that we made of the box type had channel webs with flat flanges, which had only shallow corrugations, and the rivetted joint was flat. This spar was not very efficient in steel, so we deepened the corrugations and curved the rivetted joint, and this gave a better result.