Existing approximate formulae for the thickness of laminar and turbulent boundary layers are used to derive a method of calculating the free-stream velocity distribution corresponding to a given variation of shape parameter.

Thwaites has given the formula

for the momentum thickness of a laminar boundary layer with free-stream velocity u (x). This is the integral form of the empirical equation

Hilton has described a relatively inexpensive subsonic ram-jet installation which may be used as an aid to technical education. This type of equipment should serve to enable students to undertake performance studies of propulsion systems. To this end, this author would like to elaborate on one of the testing phases suggested by Hilton, that is, the tests on combustion systems with direct coupling to the air supply. It is the purpose of these remarks to present some previous observations on the combustion characteristics of a subsonic ram-jet which will serve as a useful demonstration as well as to provide areas of interest for academic investigations.

Sporadic commercial aerial spraying operations have been undertaken in the United Kingdom for more than a decade but only over the past two or three years has it been possible for companies to make a sustained attempt to plan their work in a way which will put operations on a self-supporting annual basis.

Today, the degree to which an operator will plan his work is largely a matter for him to decide; there are few legislated requirements. The law as it stands specifically permits the work of the agricultural operator and leaves him—in the main—to order his affairs as he thinks proper. However, it cannot be long before the incidence of accidents and public anxiety about the effects of drifting chemicals brings about a change in the official attitude towards the Industry. Looking ahead we must expect some form of licensing to be introduced, which will require all operators to meet a standard set by the Ministries of Aviation and Agriculture.

As far as is known, no explicit solution exists in the literature for the displacement equations in u, v and w, for a uniform cylinder of arbitrary cross section subjected to a lateral pressure loading. However, the advent of Ref. 1 now makes available an admirable treatise devoted entirely to the analysis of thin elastic shells. The equations developed in this reference apply only to linear problems, i.e. the displacements are assumed to be small in comparison with the thickness of the shell, but they are general enough to include all shells of arbitrary curvature. Unfortunately the generality of these equations inhibits their immediate use to cylindrical shell problems, and it is the purpose of this note to present the essential features of the theory for non-circular cylinders.

As is well known, the analysis of shock waves is complicated when the gas becomes dissociated on passage through the wave. As well as showing a dependence on the Mach number of the incident flow and non-dimensional quantities characteristic of the nature of the gas, as does the analysis when applied to a perfect gas, it then also shows a dependence on the thermodynamic state of the upstream air, as described for instance by its temperature and pressure. A growing number of calculations is becoming available, especially for air in complete thermal and chemical equilibrium, but the interpolation to give results appropriate to the three independent variables (of upstream state and incident velocity) needed in any particular application can often be rather troublesome, and one has still less faith in extrapolation.

There is no doubt that there is a very definite requirement for V.T.O.L. and S.T.O.L. aircraft in Southern Africa. With the increasing tempo of development of the various territories, South of the Sahara, the need for S.T.O.L. and V.T.O.L. aircraft will increase rapidly. The aim of this paper is to point out a number of the requirements and to draw attention to some of the problems to be overcome, in connection with the application of such aircraft.

Statistical data referring to the areas, population densities and surface transport facilities of some of the African territories South of the Sahara, are given in Table I. As far as transportation facilities reflect the degree of development, it is clear that most of these territories are in a relatively underdeveloped state. In recent years, however, there has been an increasing rate of economic expansion in Africa, and with it a growing need for aircraft facilities. Apart from the usual applications, such as for passenger and freight transportation, there are duties, as follows, which are of special importance in Africa.

Flight Safety is a subject which ranges outside the control of the Aircraft Constructor and so it has been interesting to learn the other points of view from the other papers. While it should be the natural aim to see that the aircraft matches the highest standard of safety, the constructor's control over this in the hands of the operator is limited.

A polar-controlled missile is one in which manoeuvre is carried out by rotations about roll and pitch axes, that is, in the manner of a conventional aeroplane. This paper discusses some problems in the application of this form of control to homing missiles.

In comparison with the alternative Cartesian configuration, this method presents some special design problems. In the former case, it is often possible to resolve the motion into two planes and consider the pitch and yaw control systems as independent two-dimensional problems. This simplification is not possible in the case of polar control and it is usually necessary to consider the whole three-dimensional system. The equations of motion which result are, in general, not susceptible to analysis. Because of this, the design of control systems requires extensive use of simulators.

The main purpose of this note is to explain the apparent discrepancy which arises when the change in effective aspect ratio due to blowing, as predicted by the theoretically derived expression for the induced drag coefficient, is compared with what one intuitively expects from the general flow picture. If the jet sheet is considered as a chordwise extension of the wing (mechanical flap analogy), the general flow picture suggests that the effective aspect ratio of a wing without blowing is reduced by blowing. Maskell and Spence's relation for the induced drag coefficient, however, indicates that the effect of jet blowing is to increase the effective aspect ratio.

Whenever a new and truly great idea is put forward for the first time it is usually received with scorn and derision by those whom it directly concerns. Such was the initial reception of the idea of refuelling aircraft in flight.

Soon after the First World War air carnivals became very popular around the flying fields of the United States of America and it was in a search for new stunts that two intrepid fliers hit on the idea of transferring fuel by hose pipe from one aircraft to another. The two single-seater aeroplanes flew one above the other, the upper one carrying the extra fuel; in order to transfer it the pilot threw a length of hose overboard leaving it trailing behind him. The receiver aircraft then manoeuvred into position and the pilot caught the hose and put the nozzle into his reserve fuel tank. When a small quantity of fuel had been transferred, he pulled out the hose and threw it clear of his aircraft, leaving the donor aircraft to haul it in.

The concept of small stage efficiency is introduced when studying one-dimensional gas flow in nozzles in order to permit a closer approximation of real flow conditions than is possible from an isentropic analysis. It is more or less conventional to assume the flow conditions are adiabatic whenever the small stage efficiency is used. That is to say, small stage efficiency is generally considered in relation to flows contained within adiabatic boundaries, in which case it becomes a measure of the heat generated by internal frictional effects alone.

Most University students of fluid mechanics are familiar with the problem of the evaluation of the skin friction drag of a flat plate in the absence of a pressure gradient: transition is specified, usually by the free stream velocity and the transition point, or directly by the transition Reynolds number. The solution is normally obtained numerically: so far as the writer is aware, the processes used have not been written down in closed analytical form, though to do so presents no difficulty.

To predict the aerodynamical properties of a thin aerofoil, provided with a high velocity jet sheet in its trailing edge region, a simple procedure is proposed as follows. Two general separate cases concerned with the effect of a jet on an aerofoil are considered. In the first case, the jet is blown tangentially over the upper surface of the aerofoil, while in the second case, the jet is ejected at a deflection angle from the trailing edge. In this analysis a procedure which is similar to the classical Glauert treatment of thin aerofoils is applied.

Consider first the special case of a thin aerofoil placed at zero incidence in a two-dimensional inviscid flow of velocity V0, with a jet emerging with an exit velocity V1 at distance x1 from the leading edge and blown tangentially over the upper surface of the aerofoil (Fig. 1). It is assumed that an effectively attached flow may be obtained.

Expressions for the secondary circulation behind a cascade are derived in Ref. 1. A simple derivation of the same results is given in Ref. 2. The secondary flows within the blade passages and their extensions downstream are determined by the “secondary passage circulation”, Г, given by

for a diffusing cascade, and

for an accelerating cascade,

where Ul inlet velocity to cascade

z distance in spanwise direction

s blade pitch

αl, inlet flow angle

α2 outlet flow angle

Ll, distance along lower side of aerofoil

L2 distance along upper side of aerofoil

q1 velocity along lower side of aerofoil

qu velocity along upper side of aerofoil.

This note is devoted to the analysis of the initial buckling of an elastic sheet reinforced by a uniform non-buckling grid of stringers and skew ribs. The stringers and ribs enter the analysis through their influence on the stresses in the unbuckled sheet. Combinations of the following loadings in the plane of the reinforced sheet are considered: —

1. (i) uniform direct loading normal to the ribs,

2. (ii) uniform shear loading relative to axes perpendicular and parallel to the ribs.

In this lecture i want to survey some of the problems of the aerodynamics of re-entry, as they affect either purely earth-bound or space vehicles; and in particular, as they are affected by the trajectory the vehicles are designed to follow, or may find themselves upon due to some error of navigation. This is a self-set task and an ambitious one: but in truth it is an artful one, as it provides an excuse for me to leave the discussion of problems at a stage where their difficulties begin to defeat me.

The Soviet Deputy Premier, Mr. Anastas Mikoyan, is reported to have stated recently that Russia has a missile ready to “visit the Sun.“

The Russians have been achieving a notable series of “firsts” in space exploration, and this statement may have led some to speculate on whether they will be the first to reach the Sun.

It is, of course, strictly impossible to talk in terms of hitting or reaching the Sun, as it has no solid surface. Indeed the streams of matter and radiation it emits travel out into space beyond the orbit of our planet. However, for practical purposes the Sun is opaque over a diameter of just under a million miles, and this constitutes a generally agreed boundary for purposes of such a study as this.

Conditions on the bodies that constitute the Solar system are dominated by the Sun, and this alone would justify the continued examination of its behaviour. Additional justification is provided by the fundamental knowledge of matter obtained through observing the Sun and its radiated energy.

For some years the author has been interested in subsonic ram-jets as a means of helicopter rotor tip propulsion and has done a considerable amount of experimental work with this end in view. Most of the effort has been concentrated on producing engines to operate at the lower end of the speed range as it was thought that, however simple a ram-jet may be, this advantage is lost when other means of propulsion are needed for starting purposes.