Navigation used to be solely concerned with the safest and most expedient means of directing an aircraft to its objective—either the destination airport or a military target. Nowadays, especially in civil aviation but increasingly in military transport operations, the need to comply with air traffic control (A.T.C.) procedures is tending to dominate both the technique of navigation and the kind of navigation aids used.

In recent years great stress has been placed on the problem of air traffic control and now, with the imminent arrival of jet air liners in large numbers, the consternation is even greater. Reactions to the problem vary, so that on the one hand there are the down-to-earth realists who see no immediate prospects of any revolutionary improvement in A.T.C. methods; on the other hand there are the optimists who already speak of the present A.T.C. system as though it is a thing of the past and talk of the “ new “ system which will replace it when the jets arrive. Despite the most extensive studies of the problem, such as that recently undertaken by the Curtis Presidential Committee in the United States, no entirely satisfactory description of the “ new “ system of A.T.C. has materialised. Meanwhile the penalities of restriction and delay of jet aircraft by air traffic control need no emphasis, but to give one example, the Comet I, when operated by B.O.A.C., regularly arrived at London Airport with at least two hours fuel as diversion and traffic reserve. The weight of this fuel was of a similar order to the total payload of the aeroplane, so it will be realised that economic operation of jet aircraft can stand or fall on this single issue of air traffic control.

Inertial navigation is a completely new approach to the navigational problem initiated to a very large extent by the military requirement for a blind navigational system which could not be jammed by, nor give actual assistance to, any potential enemy. It relies for its operation on principles which were understood by Newton, but the practical realisation of a working system has become possible only by the intensive development in both the design and manufacturing techniques of gyroscopes and accelerometers. This development work has, to a considerable extent, been stimulated by Dr. Draper of the Massachusetts Institute of Technology and, although he may not be the inventor of inertial navigation as such, there is little doubt that but for the work carried out under his direction, inertial navigation would still be little more than a dream.

Inertial navigation depends basically on the simple fact that if we can measure the acceleration vector of a body in any convenient axis system, then by carrying out the suitable integration processes we can determine its path in space, its position and its distance from its initial position.

With modern air liners flying at altitudes of 20,000 ft. or more, the question of passenger safety in the event of pressure cabin failure has become a real problem. Should failure occur, the Captain of an air liner flying over the sea, or difficult country, would have to decide between exposing his passengers to the anoxic effects of high altitude or of accepting the increased fuel consumption which would result from flight at a lower altitude.

An Emergency Passenger Oxygen System to enable the flight to continue at an altitude where fuel consumption would not be excessive has been developed recently by the Walter Kidde Co. Ltd. in conjunction with the Scott Aviation Corporation of America. The Mask Presentation Units included with this system are unobtrusively located in the luggage rack and, in the event of pressure cabin failure, an oxygen mask is automatically presented in front of the head of each passenger. It is then only necessary for the passenger to pull the mask on to his face to obtain a supply of oxygen at sufficient flow to safeguard him until the aircraft has been brought down to a lower altitude. In addition, each Presentation Unit includes an attachment point for medicinal or therapeutic oxygen, which is independent of the emergency system, and from which a supply is always available. Leakage from these points when not in use is prevented by self-sealing outlets. The Presentation Units are easily removable for overhaul purposes, and can be adjusted for a change of seat layout. A manually operated cock enables a crew member to operate the system if necessary. Fig. 1 illustrates the system in use.

On the face of it boundary layer problems at hypersonic speed present enormous difficulties. However some aspects have turned out to be somewhat simpler than was visualised some years ago, and with the aid of certain simplifying assumptions many problems have been solved, at least to a good design approximation, and inaccuracies in the results are due not so much to the approximations involved, but to our lack of knowledge of the physical properties of air such as viscosity and Lewis number.

A surface-to-air guided weapon system is the result of many years work by a large and diverse team and includes radars and fire control equipment as well as the actual missile. In the time available it is impossible to cover the whole weapon system and therefore no apology is made for concentrating on the development history of the missile itself. It must be remembered, however, that there are many parts of the Bloodhound weapon system, a major contribution to the whole, which will not be mentioned.

Summary: Modern radar techniques have found wide application in the fields of aeronautics and guided missiles and to make full use of these techniques the designer of modern aircraft and missile systems requires a knowledge of the basic radar principles. This paper is an introduction to these principles. Four main functions of radar are discussed, namely the detection of objects in the beam, measurement of range, information on direction, and the use of the doppler principle to measure velocity and to distinguish moving objects. The discussion is confined to primary or self-contained radars although the principles are applicable to navigation aids such as Gee and Loran. The paper concludes with a brief description of the radome problem.

I claim to have no expert knowledge on landing aids, but the Aeronautical Research Laboratories in Australia have done some work in this field. We were invited, or encouraged, to take up this branch of work by a Meeting of the Commonwealth Advisory Aeronautical Research Council in Australia in 1955, when the difficulties of the landing phase and the need for some form of aid for the pilot were emphasised.

I need say nothing about the difficulties of the pilot: they have already been amply emphasised. An early example of operational research in this field was an investigation made by Professor Collar in 1941 on the problem of the dark night take-off, when the pilot tends to mistake forward acceleration for a climb in the absence of sufficient external visual cues.

The Flow of Fluids through screens has been widely studied with particular importance being attached to the measurement of the pressure drop caused by a screen and its relation to the screen geometry and the flow conditions. The majority of the investigations have been carried out on wire gauze screens mounted in ducts with air passing through them, the static pressure being measured on either side of the gauze. Attempts have been made by Weighardt Annand and Grootenhuisto correlate the gauze geometry with the pressure drop and to enable the pressure loss over a given screen and with given flow conditions to be predicted.

Those who have followed a career similar to mine have generally displayed an interest in things mechanical from an early age. I was true to type in this respect, and showed my liking for making things from as early as I can remember. This was not because I was taught to do so, for my father died when I was only six. However, I inherited a fine kit of tools which I had seen him use, and I taught myself to use them.

As early as 1910 I constructed some balloons, one about 15 ft. in diameter which rose fully 1,000 ft. and drifted miles over the countryside. I made large kites and some model aeroplanes with elastic motors which flew short distances.

In a recent paper(1) Collar discussed some aeronautical applications of linear differential equations with variable coefficients. Part of the paper deals with the approximate solution:

of the differential equation

This asymptotic approximation, which dates back at least to Liouville, has an interesting history(2). It is widely known as the WKB approximation because of its use in quantum theory by Wentzel, Kramers and Brillouin. It has been applied to compressible flow by Imai(3).

While very useful it breaks down at the zeros of n(t) and there are problems in joining solutions passing through such points. Recently(2,4,5) extensions of the approximation which circumvent this difficulty have been developed. This note deals with the extension due to Bailey.

This approximation can be developed from the equivalence of equation (2) and the Riccati equation: —

The College owes its origin to the early days of NATO when the first Supreme Allied Commander Europe, General Eisenhower, was confronted with the problem of finding suitably trained staff to fill the posts in the NATO organisation. He therefore proposed to the Standing Group that a Defense College should be formed to fulfil this function. This proposal was agreed and the French Government set aside part of the historic Ecole Militaire building in Paris to house the college. The first course began in November 1951, some two years after the signing of the North Atlantic Treaty and since then fifteen courses have been held, each of approximately six months duration.

The first Commandant was Admiral Lemonnier of France, who was succeeded by Air Marshal Sir Lawrence Darvall, R.A.F., Great Britain, Lieutenant General Clovis E. Byers, United States Army, Lieutenant General de Renzi, Italian Army, and Major General Estcourt, British Army. The present Commandant is Lieutenant General Ariburun of the Turkish Air Force.

An Annular Fairing can be used to control the flow through an airscrew, which is then generally referred to as a ducted fan. There are obvious affinities between such a fairing and the fairings used to control the flow through turbo-jet engines, but there are certain significant differences which have to be recognised when such fairings are designed. In particular, a fairing for a ducted fan is usually much shorter than one for a turbo-jet engine. Whereas it is usually convenient and justifiable to treat the internal and external flows of a turbo-jet nacelle separately and to consider the interactions between the intake and nozzle to be small, a short fairing must be treated as a whole. The simple calculations made in this note may give some indication of the order of fairing length where this becomes necessary.

In this Note the reheat thrust boost for a turbo-jet engine is shown to depend upon various dimensionless parameters, one of which is engine pressure level. The importance of this ratio is illustrated graphically and it is shown to be most important over the range normally encountered on a test bed. It is shown that a given reheat system would deliver a higher thrust boost on a high pressure level engine than it would on a low pressure level engine. Finally, the pressure level effect on the thrust from an engine having a reheat system fitted but operating with the reheat unlit is discussed.

Having agreed with Dr. Shercliff that I would discuss dissociation and its applications, after which he would speak about ionisation and its applications, it seemed appropriate that I should repeat the lecture I gave to the International Congress of the Aeronautical Sciences on “Dynamics of a Dissociating Gas”—although with apologies to those few in the audience who may have come back from Madrid with memories of anything except Flamenco and Paella and Goya and Sangria.

This note is concerned with the evaluation of the finite sum

where the m quantities Zi are arbitrary and where

is the binomial coefficient in a series of n terms. Summations of this kind appear in the evaluation of matrix products involving the reciprocal of order n of a segment of a Hilbert matrix or of a generalised Hilbert matrix. Such products are found, for example, in the representation of a lifting aerodynamical surface by a set of horseshoe vortices.

Let the m factors (r+Zi) be multiplied out, and let Pl be the sum ∑Zi, P2 the sum of the products taken in pairs, and so on; then

The aircraft designer must clearly ensure that his aircraft will fly in all climatic conditions normally to be expected. Over and above this, aircraft must be able to cope with a change in weather also.

Since the last war, research into the problem of ice accretion on aircraft has done much to widen understanding of this serious flying hazard. In the flight testing and development of ice protection systems for aircraft, however, one of the principal difficulties encountered is that of finding natural icing conditions sufficiently uniform through which to fly the test aircraft. Because of this it has been found more profitable not to seek natural conditions, but instead to fly in clear air at temperatures below 0°C, while spraying the test surface from a water spray rake fitted to the test aircraft.

It is shown that, for infinite sheared wings with symmetrical aerofoil sections, the value of the suction peak near the nose in incompressible flow depends primarily on the value of the lift coefficient and the nose radius and not on the angle of sweep.

When investigating the suitability of a basic wing section for an aircraft design with comparatively large aspect ratio, it is useful to know up to which lift coefficient one can expect the flow to be attached over the wing surface, and separation to occur at the trailing edge only. For aerofoils of small or moderate thickness-chord ratio, flow separation tends to occur first near the leading edge.