Patel And Venkatraman have studied the general behaviour in bending of a thin-walled channel section (Fig. 1) made of non-linear elastic material which deforms in simple tension according to the law

where ε represents strain, σ direct stress and λ, n the relevant material properties. (It is understood that a negative sign is inserted in where this is necessary to make σ and ε have the same sign.) As Patel and Venkatraman explain, the results are, by a trivial substitution, applicable to steady creep behaviour of the channel section.

The Minister of Aviation has expressed his interest in the work of the Air Law Group of the Royal Aeronautical Society, and has offered his best wishes for its success. One of the valuable things about the Group is that it will provide a forum where problems of air law can be discussed, quite unofficially, by those responsible for advising the manufacturers, operators and insurers of aircraft, by those who act for travellers, and shippers by air, and by those whose duty it is to advise the Government on matters of civil aviation law. All this under the watchful eye of technical experts, who will ensure that legal doctrine does not stray too far from the realities of actual flying.

Some aerodynamic properties of auto-rotating or forcibly rotated cylinders and aerofoils were investigated even prior to the beginning of aviation and, somewhat surprisingly, it was Maxwell who wrote the earliest (1853) known paper on the subject. That entirely non-mathematical paper tried to explain the curious behaviour of an oblong card which, left to fall freely in the air, started immediately to rotate about its longitudinal axis while deviating from the vertical in the horizontal direction perpendicular to the axis of rotation. Steady “terminal” conditions are soon reached in which speed, rate of rotation, and path angle, are all constant. This simple experiment revealed at once two important properties of an “aerofoil of large aspect ratio“: (1) ability to autorotate, and (2) ability, when rotating in an air stream, to create an asymmetrical pressure distribution resulting in a force normal to both axis of rotation and mainstream velocity. About the same time, the famous “Magnus effect” on rotating circular cylinders was discovered, but it was not before the Kutta-Joukowski theory of aerodynamic lift appeared some 50 years later that a more general understanding of the “lift through circulation” principle became possible. Magnus effect found important applications in ballistics, and one serious (although not economically successful) attempt was made to apply it in maritime navigation (Flettner's rotorship). As to the use of aerofoils rotating about a horizontal transverse axis for generating lift in aircraft, very little indeed has been done apart from some early publications. The concept of a wing with rotating flap as a lift-augmenting or control device arose from suggestions by Riabouchinsky and Chappedelaine, and there were some early French and German patents based on this concept. However, the matter was soon abandoned. It was taken up again during the last war in Germany, where some interesting experimental and theoretical research was done on a small scale. The subject has apparently never attracted any attention in Britain until 1957 when a short review of the existing information was given by Crabtree. This was followed by the lecturer's own effort which concentrated on the relevant mathematical theory.

Graphical and experimental methods exist for the determination of the local shearing stress and heat flux on the boundary of a duct of constant cross section in a fully developed turbulent flow. While the graphical method (see for example Ref. 1) is simple to effect, the premise on which it is based is questionable and even so a high order of drawing accuracy is necessary for reliable results. In the graphical method, it is assumed that there is no turbulent stress on surfaces which are perpendicular to the w-velocity contours (see Fig. 1). The shearing forces on the elemental area which is subtended at the boundary are then equated to the difference between the pressure forces acting over the elemental area of the duct cross section. This is a clever technique, but the use of surfaces across which the w-velocity gradient is zero for the calculation of the boundary stress needs more justification. Similarly, for heat flux distribution by a graphical method, it is difficult to determine the planes in the duct across which there is no turbulent heat transfer. As for the stress, surfaces across which there is no temperature gradient are not necessarily coincident with surfaces of zero heat flow. For the experimental determination of the wall stress, the ingenious Preston tube is available, but for the heat flux there is no simple counterpart. Heat meters (and their associated instruments) which are sometimes used are difficult to manufacture and their data must be treated with care.

In the past ten years or so a number of changes have taken place in aircraft which have progressively reduced the potential tyre life and tend therefore to increase the operational cost. We now see that the latest aircraft have developed to such a stage that there is a certain hazard in stopping them on wet or slush covered runways. To ease this situation, further changes are recommended to the tyres, likely still further to reduce tyre life.

For many years, studies of various light aircraft designs have been carried on by the Lockheed-California Company in search of a vehicle that had the potential of truly generating the “air age”—a vehicle which would perform a useful service to many people, in many jobs. Shortly after the Second World War, these studies were directed along the lines of present-day light aeroplanes, but were eventually discarded upon recognition of the limited utility of these vehicles when related to general public acceptance. However, in 1959, spurred by recent developments in VTOL craft, the Lockheed research team again raised the question, “Is it possible today to develop a vehicle of low cost and with sufficient utility to reach the mass market?”

Finite bodies supporting two-dimensional under surface flows behind “contained” plane shock waves of the type discussed by Professor Nonweiler in a recent paper are currently receiving attention from both theoretical and experimental workers. The experimental work already undertaken by the RAE has given hopeful indications that such bodies, characterised by a re-entrant lower surface in cross section, compete closely with more familiar convex bodies in terms of lift/drag ratio, and furthermore preserve the two-dimensional character of the flow away from the design incidence.

The purpose of this note is to point out that:

(a) Delta wings with inverted V or W cross sections are geometrically simple examples of a more general family of possible shapes supporting two-dimensional flow behind a plane shock.

(b) The concept may be extended to bodies supporting two-dimensional flows with multiple shocks (leading to isentropic compression in the limit) or shock-expansion systems.

The title of this paper permits considerable latitude; also, there have been several previous papers on rather similar subjects. It seems best to explain therefore that the two primary purposes of this paper are, first, to bring the entire VTOL coverage of NASA's Langley Research Center up to date; and, second, to review a segment not covered in the references mentioned, namely, helicopter research. Also included are background history, and indications of the direction in which the research seems headed.

During the flight development of a high altitude bomber some difficulty was encountered in the measurement of static pressure error, due, in the main, to the relatively high ceiling and Mach number limits of the aircraft.

There was found to be a need for a method that was self-contained within the test aircraft, allowing a complete flexibility of test conditions. This report describes the method evolved which requires the use of ai radio altimeter and a low speed trailing static head.

Following the Second World War, agricultural aircraft use increased rapidly in the United States, but appears to have levelled off in the past five years. California is one of the largest users of agricultural aircraft of any State, with an estimated 8 million acres treated per year. This figure includes all applications of insecticides, fungicides, and herbicides, plus seeding, fertilising, and defoliation of agricultural crops, grasslands and forest areas. Also, this figure represents acres covered and includes duplicated applications. Certain crops, such as cotton, may have as many as four or five separate treatments during the season.

The problem of two identical circular holes in an infinite sheet has been solved by Ling using bipolar co-ordinates and taking advantage of the double symmetry.

The case of any two unequal holes is of interest in that one common situation is that of a small circular hole close to a relatively larger one. In this case it is tempting merely to use the classical single hole solution, first for the larger hole and then for the small hole situated in the “uniform” stress field produced by the larger one. The accuracy of this simple method of superposition is examined.

The notation of Muskhelishvili is followed where the problem consists of finding two functions of the complex variable z=x+iy which are analytic in the region and satisfy the boundary conditions on both holes and at infinity.

A method is described by which blades of aerofoil section can be manufactured on a laboratory scale. Emphasis has been placed upon cheapness, rapid production, and the ability to obtain an accurate representation of the blade profile for a large aspect ratio of 3·5. In addition, for a series of experiments with a cascade in water, the blades were to be made from a material which did not require the use of a protective paint on the surfaces. To satisfy the above requirements a casting process was adopted, and the blades were made from a plastic resin material. Although the discussion presented is confined to the production of blades, the method can easily be extended to the manufacture of impeller hubs, fairings, nozzles, and so on.

When an aircraft lands on a runway on which there are extensive puddles, it appears that sometimes the water exerts a large upwards force on the wheels, so preventing them from making contact with the ground. The wheels are then said to “aquaplane”. In the aquaplaning condition the braking effectiveness of the wheels is reduced virtually to zero, and even at touch-down speeds insufficient to cause aquaplaning, when there is some contact between the wheels and the ground, water on the runway may cause appreciable reductions of runway friction forces. This note offers some tentative suggestions concerning the nature of the water flow when aquaplaning occurs, and is put forward as a basis for discussion of this important practical problem.

In their paper, “A Theory of the Cylindrical Ejector Supersonic Propelling Nozzle”, Pearson, Holliday and Smith analysed the conditions under which two unmixed streams of air pass together through a nozzle. Two criteria were used to determine the flow conditions at the exit, when the nozzle is choked: —

(a) That the stagnation pressure in the secondary (subsonic) jet should be a minimum for a given flow quantity.

(b) That the velocity of propagation of small plane waves at the exit should be zero.

Either criterion, applied independently, led to the same result but, as the authors observed, neither has the status of an axiom in fluid mechanics, and a direct proof without invoking either would be preferable.

Rotary atomisers, initially of brush and disc design, but subsequently superceded by a rotating cage device , have for some while been used with fixed-wing aircraft for producing relatively finely dispersed homogeneous liquid sprays. Common to all these types is rotation in the vertical plane with axial liquid feed intended to give uniform discharge from the rotor periphery. Atomisation, for a given liquid and a fixed rotor diameter, is a function both of the rotor speed and also of the airspeed of the aircraft. In combination these two factors determine the resultant shear force producing break-up of the discharging liquid filaments. With fixed-wing aircraft, having a minimum forward speed of, say, 60 mph, it is ultimately this velocity which determines a theoretical upper limit to the size of droplet which may be produced, but in practice drop size also varies with throughput, and, in connection with anti-Locust spray work, Sayer has found that the normal droplet spectra may be considerably coarsened by dispensing with the orifice feed restrictors and non-drip valves, thus allowing the rotor feed rate to rise to three to four times the design figure.

In this article a magnetic suspension and balance system suitable for wind tunnel application is discussed. General considerations are presented that illustrate the nature of the problems to be solved as well as one solution of these problems.Finally some initial wind tunnel data are presented.

My Talk will be Brief because Mr. Kean has covered the field extensively and extremely well.

What is Interchange? Mr. Kean indicated that it is not a very satisfactory description of what takes place because it is not a word which describes it accurately, and I think a good deal of confusion about interchange exists in the minds of many laymen because, unlike most air transport words which had their roots in surface transport, interchange so far as I know is peculiar to air transport; hence people are apt to think that it is something special, and that special rules must apply to it. In fact I suggest that it is nothing of the kind; all it is is a certain kind of charter, and the same rules apply to interchange of aircraft as to any other kind of charter, and the reason that it has been singled out as a special problem for lawyers is that its characteristics make it extremely difficult to work satisfactorily, internationally particularly, if the normal rules are applied.

Incidence and sideslip must be measured accurately in aircraft performance and stability tests. A convenient method is to install wind vanes on a nose boom. When only one sideslip and one incidence vane are fitted, mutual interference occurs, and the vanes do not indicate the true flow direction. This interference can be 0·5° at 0° incidence at subsonic and supersonic speeds. Thus a symmetric configuration of vanes is essential for accurate measurements of incidence and sideslip.

A cruciform arrangement of four wind vanes was fitted around the nose boom Pitot head of the Fairey Delta 2 supersonic research aircraft. The effect of the Pitot boom on the vane sensitivity was determined by a calibration of the aircraft vanes on a duplicate Pitot-static head in the R.A.E. Bedford 3 ft wind tunnel.

The effects of the fuselage and the wing upwash are only present at subsonic speeds and can be estimated.