In a necessarily brief introduction it is best to choose a few topics which seem to me to be of first–class importance, and to leave it to the discussion to bring up others.

I wish it had been possible to include one other aspect of Naval aircraft in these introductory papers– the aircraft carrier. Many of the technical aspects of carriers may be more appropriate as a subject for the Institute of Naval Architects, but I feel that our discussion will be incomplete unless ship designers contribute.

Work on the Goblin engine was started in 1941 when, at the invitation of the Ministry of Aircraft Production, the de Havilland Enterprise began to interest itself in jet propulsion. At this time de Havillands were much in ignorance of the work of Air Commodore Whittle, the Royal Aircraft Establishment and the Gloster Company in this field. The first step was to study what had already been done and in this connection the fullest co-operation was offered by all concerned. The author would like to express the appreciation of the organisation with which he is associated for the material help received in those early days by way of advice, data and drawings. As a result, it was possible to start fully abreast of what was being done in this country. The benefits of further experience and mutual assistance from the pioneers in jet propulsion were fostered by a process of frank discussion and exchange of information, finally to be cemented by the formation of the Gas Turbine Collaboration Committee.

In choosing the title, “The Development of All–Wing Aircraft,” as the subject of my lecture I run some risk of being accused of writing a company history rather than a paper of the broad scope ordinarily presented before this time–honoured institution. This is far from my intent, but being sincerely convinced that the all–wing aeroplane is a valuable step in the development of aeronautics, and desiring to contribute a maximum amount to the available data in the limited time at my disposal, my paper must be confined largely to experience gained by our company in its work on this subject.

“Potential” leads are used to put strain gauge switches and leads in series with high resistance ratio arms in a modified Wheat-stone Bridge. Thus the effects of switch contact resistance change and temperature-resistance change in leads can be minimised to any desired values. The high resistance ratio arms allow coarse resistance changes at the measuring bridge to measure the small resistance change at the gauge due to strain.

High potentials are applied to the bridge to minimise the effects of thermal e.m.f.

Active gauges and the temperature compensating gauges are in circuit for only a few seconds while the measurement is made.

A meeting of the Society was held in the Great Hall of the Institution of Civil Engineers, Great George Street, Westminster, S.W.1, on Thursday, 31st October, 1946, at which a paper on “Aeroelastic Problems at High Speed,” by Professor A. R. Collar, M.A., D.Sc, F.R.Ae.S., was presented and discussed. In the Chair, Dr. H. Roxbee Cox (Vice-President).

In the opinion of the writer the bald name “ Pressurisation ” gives a crude and misleading picture of the developments which are now in hand and both he and the organisation to which he belongs, prefer to speak of “ Cabin Air Control,” as this name gives a clearer picture of the scope of the developments which are the subject of this paper.

At the outbreak of the war the evolution of passenger-carrying aircraft had reached a stage where a great deal of attention was desirable for the comfort of passengers and, in those passenger-carrying aircraft which have subsequently gone into service, it is fair to describe Pressurisation as a development directed almost entirely towards the greater comfort of the occupants.

When I was asked to give this lecture on Civil Flight Testing, I considered in what way any of my experience might be of general help to the Industry.

The tests which A. and A.E.E. make on civil aircraft are at the moment of three kinds: —

1. (a) Tests to prove compliance with Air Registration Board requirements for a Certificate of Airworthiness.

2. (b) Development tests for firms in order to suggest modifications to the aircraft occasioned by the results of tests made under (a).

3. (c) Tests made for the Ministry of Supply because some of the aircraft are for Ministry of Supply contracts.

Never, at any time since the Wright Brothers made their first flight have the means of propulsion exercised a more dominant influence over the shape of aircraft or the shape of things to come, nor can it have been so difficult to forecast the form resulting from that influence. It has been a platitude for some time past to say that aircraft and engine design are mutually interdependent: now it is more than a platitude, it is a fact, and one to which we have not yet grown accustomed.

That power installations can no longer be procured “off the peg” is to-day an article of faith which is generally professed: what is rarer is an appreciation of the implications of this state of affairs. Pursued to its logical conclusion, the implication is that a new aircraft and its means of propulsion should originate in the same brain, and be designed, developed and manufactured under the guidance of that brain.

A few months ago I was asked to deliver a lecture to the Royal United Services Institution on the Radio War. In the preamble to that lecture I explained that my treatment of the subject would not consist of a description of the various radio devices which were used in the late war for purposes of communication, early warning and air navigation, but rather of a treatise on the methods that were employed to deny to our enemies the use of their radio services. My lecture dealt mainly, therefore, with the use of radio as a weapon; and the tactics that we evolved to exploit its employment for such a purpose not only in the defence of this country, but also in the protection of our bomber forces when attacking targets in enemy territory.

A meeting of the Royal Aeronautical Society was held in the lecture hall of the Institution of Civil Engineers at Great George Street, Westminster, London, S.W.1, on Thursday 5th December 1946, at which a paper by Mr. J. K. Hardy on “ The Protection of Aircraft Against Ice,” was presented and discussed. In the Chair, the President, Sir Frederick Handley Page, C.B.E.

In recent years some types of aircraft have shown signs of structural trouble due to repeated loading and exploratory thought has therefore been given to the general problems arising. There are two main aspects to be considered: the nature and magnitude of the loads repeatedly occurring in flight and the behaviour and strength of aircraft structures under such loads. In this country a good deal of attention has already been given to the first side of the question, mainly by V-g recorder work, but also by some strain gauge investigations, but the other side of the matter—the resistance of aircraft structures to repeated loading— has so far received less attention. Direct experiments have not in this country gone much beyond exploratory work on a series of Typhoon tailplanes, described by Oaks and Townshend.

The object of this paper is to discuss the evolution of the wartime fighters the Spitfire and Seafire, designed by the Supermarine Works of Vickers–Armstrongs Ltd. In particular, it will be confined to the design and technical side of the problem. The production undertaking, which resulted in the manufacture of over 22,000 of these aircraft in 33 different types, would undoubtedly need a paper of its own.

In order to make the matter clear it is proposed to begin with a brief history of the early development of high speed aircraft by the firm. The next logical step is to survey the Spitfire family as a whole and to trace the relative importance of the different types, giving some indication of their line of development. Finally, an attempt will be made to analyse the factors which maintained the efficiency of these aircraft at a high level for a period of ten years.

In a search for a rational basis for a transport-economical comparison of jet and airscrew propulsion of aircraft, a method has been developed which is generally applicable for evaluating any kind of propulsion of aircraft, as well as the efficiency of any principle or type of aeroplane design. The method is based on the assumption that the ratio between the useful load and the gross weight (or empty weight)—when related to the speed —is representative for the overall efficiency of the aircraft, including the power plant, from a transport point of view. General equations have been deduced for this useful load ratio as functions of, in addition to the speed and altitude, all major design parameters, as wing loading, power loading (or thrust loading for jet aeroplanes), specific engine weight, specific fuel consumption, parasite drag coefficient, effective aspect ratio, and two structural weight coefficients. This has been possible by the deduction of a formula for the gross weight, which appears to be usable even for general analysis of other aircraft performances, whenever the useful load has to be considered.

The method presented has been applied in this paper particularly for a comparison between jet-propelled aeroplanes and piston engine-airscrew aeroplanes. This has revealed that pure jet propulsion seems to be superior to the conventional system at speeds as low as 200 to 300 m.p.h., depending upon the duration in hours of flight and the detailed assumptions made.

Lack of accurate data for the gas turbineairscrew combination has prevented the writer from making a closer investigation of this system, but a preliminary study of the same kind seems to indicate that the turbineairscrew aeroplane—although for most purposes definitely superior to the piston engine aeroplane—is inferior to the pure jet aeroplane for durations up to about two hours of flight. If, however, all the mechanical complications involved in retaining the airscrew are taken into consideration, it appears doubtful whether the turbine-airscrew system will be any more than an intermediate step in aeronautical development. At the best, it might remain only for extremely long ranges, or transport of cargo at comparatively low speeds.

The conclusions drawn are based on the present stage of development of jet engines, but naturally it will take at least some three to six years before the jet aeroplanes contemplated are built and put into service.

There are a number of essential differences between aircraft designed to operate from carriers and those designed to operate solely from land bases. Some of the features are detrimental to good structural weight and even to aerodynamic performance, and involve both the aircraft and carrier in special equipment.

Of these features the two most important are assisted take–off and deck landing. Assisted take–off includes catapulting, accelerating and rocket assistance; landing involves arresting and safety–barriers.

It is now the practice to refer to all methods of mechanically–assisted take–off as catapulting, to bring it into line with American terminology. Until recently, catapulting denoted a particular method of launching whereby the aircraft was supported entirely on a cradle with no part of the airframe in contact with the ship structure, and such equipment was installed in ships with no flight deck. Accelerating denoted that the aircraft was launched along the deck on its own undercarriage which gave it some degree of support. Accelerating was peculiar to ships with flight decks, i.e. carriers.

A Fire Prevention Sub-Committee of the Aeronautical Research Council published its findings in 1922. At that time the major risk was from crash fires in which the fuel was ignited by the engine either directly or indirectly through the medium of oil, wood, fabric or dry grass. Preventive measures recommended included crash-proof tanks, with a suggestion that these should be carried on the wings; fire-proof bulkheads; fire-proofing of inflammable materials; cooling of exhaust pipes; and fire-proofing of magnetos. Fires in flight were usually in the carburettor and a successful carbon tetrachloride extinguisher was designed at the Royal Aircraft Establishment and tested in flight by the late Squadron Leader Norman. However, the weight of the system, about 35 lb. per engine, was considered excessive and the action recommended was to turn off the fuel and dive the aeroplane.

The recent war has provided a great deal of experience in the operation of aircraft and ground equipment under a variety of conditions. This paper is an attempt to condense and correlate some of the points noted into a logical sequence. It is not based on statistics and is more in the nature of a selection of problems and impressions about them. Possibly this is an advantage, as it seems doubtful if many logical conclusions could be drawn from a set of completely comprehensive observations, even if these were available.

In this paper an attempt has been made to trace the influence of gross weight, as the accepted measure of size, upon the dimensions of hulls and fuselages and from this, to evaluate the probable trend of the weights of these components with increasing gross weight.

During the past few years the size andgross weight of aircraft have rapidly increased and there appears at the moment little, if any, structural limit upon the size and gross weights attainable, since it can be shown that the percentage weights of hulls and fuselages tend to decrease as size increases.

Until recently the gust requirements laid down by the airworthiness authorities had not caused any serious difficulty in design. This was due to the fact that other loading conditions (manœuvring loads imposed by the pilot) had been more severe than the loads produced by gusts. Over the past few years, various factors have altered this position. Increase of aeroplane speeds, increase of operating altitudes, decrease of the manœuvring loads (in the case of large aeroplanes) and increase of size, have each contributed to raise the gust loads until they have become, in many cases, the main design criteria for the flight structure.

My subject is too big to cover adequately in the time at my disposal and as I have been asked to emphasise the wartime experience in aircraft factories, I propose to confine myself to a few of the most interesting problems.

Because of the urgent necessity to produce aircraft quickly in wartime the production engineer has a greater influence on design than normally, and many design problems are usually settled by a compromise between the requirement of the designer and the production engineer.

The designer attempts to satisfy the aerodynamic requirements at the lowest possible weight and the production engineer has to consider the shop equipment and floor space available, the type and availability of labour and ensure that the aircraft can be built in a minimum of man–hours.

An analytical method is developed for calculating the speed and climb performance of jet-propelled aircraft, given the drag and thrust data. A method is also given for dealing with the effects of compressibility and the results in a typical example are included to illustrate the form of curves obtained.

In the past, when dealing with aircraft driven by reciprocating i-c engines and propellers it has not been possible, even on the assumption of the available power being independent of forward speed, to evolve an analytical method of calculating the complete level speed and rate-of-climb performance of the aircraft, because the level speed equation is a cubic, for which there is no general solution, while even a constant speed propeller causes the thrust horse power in the region of the best climbing speed to vary with forward speed in some manner that cannot be expressed as a simple function.