The development of a special model aeroplane technique is reviewed which renders possible easy and illustrative experimenting In the Reynolds number regime from 1 to 5000. The models are built in extremely light-weight construction; with wing span from 0·1 to 1 metre and all-up weights from 0·01 to 2 grammes, flight velocities between 0·1 and 1 m/ sec are reached. The requirement of extremely low wing loading, together with the special air flow characteristics in this region, leads to rather unconventional construction principles with the materials balsa wood, nichrome wire and cellulose film. These principles are reviewed briefly. The problem of optimum propulsion for such model aeroplanes is treated analytically. Some results are given for flight performance optimisation. By combining theory and experiment there has been evolved, e.g. the Schwebeleistungs method (power required for horizontal flight) for optimising the duration of indoor model aeroplanes without exact knowledge of their aerodynamic characteristics. Flight characteristics with some elasticity of the structure present formidable problems and are reviewed in some examples. Finally, some problems of hangar meteorology are mentioned.

Although the science of Hovercraft is still in its infancy, sufficient promise is already being shown to indicate a commercial and military future as alternative means of transportation. Since transportation involves power, and power involves noise, it is imperative that even at this early stage, development does not proceed in a direction which involves excessive noise and in so doing builds up the embarrassing situation for itself of the kind now occurring with aircraft at London Airport.

To give an example, one of the major problems in establishing a third airport for London is obtaining a quick method of communication between such an airport and the centre of the city. Unless this can be achieved, the advantages of supersonic travel will be nullified. The roadways and railroads are already full and alternative forms of travel must be found.

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.

From some points of view this is a difficult time to be giving a general talk on supersonic civil transports. The pioneering period is over, and the really interesting lectures when bright new ideas and shapes were discussed have mostly all been given. The design of the Anglo-French “Concord” is now pretty well settled and a fair amount of information about it has been made public. The information which has not been made public is withheld for obvious reasons of commercial security, and I am therefore caught between not giving too much away on the present Concord and repeating a lot which has already been said.

Just over two years ago, on the occasion of the inaugural de Havilland lecture, Richard Clarkson gave one of the finest accounts of an aviation pioneer and his work that I have ever heard. When I was asked to give this second lecture, I felt more than a little conscious of the standard set by my predecessor and by the quality of the man thee lectures commemorate.

The Airline is satisfying a demand, a demand for transportation. Such transportation is not something in itself—people do not simply go for the ride—but is part of a bigger demand. The airline attempts to create, stimulate and, to some extent, change this demand by tariff and other means but nevertheless it is attempting to satisfy a naked demand as it arises. If the demand is for 8 a.m. out of Glasgow, we as an airline—contrary to popular opinion— attempt to satisfy the demand at that time within the overall context of profitability. In a competitive situation—and this includes competition with other forms of transport, not simply air, as well as other forms of consumer expenditure—the airline's ability to take of this demand what suits it and ignore the rest, is strictly limited. The success of an airline depends upon the efficiency with which it satisfies this demand.

The June 1963 Report of the Inter-Departmental Committee on the Third London Airport concluded that a third London Airport would be required in the early 1970's, and possibly a fourth soon after 1980. It also brought out that because of the large amounts of air space required for the sequencing areas and approach paths of each airport, and because of limitations imposed by the positioning of the main air traffic routeings, the choice of possible sites within reasonable distance of Central London for the third airport was severely restricted. In a postscript to the Report, it was recognised that after the third airport has taken over a further block of air space, the difficulty of siting a fourth airport would be even more severe.

A stiffened panel, designed so that failure in compression will occur afterinitial buckling, suffers a loss of axial stiffness due mainly to buckling of the skin between stringers and a consequent loss of flexural rigidity of the panel as a whole. The stringers will then carry an increasing proportion of the total compressive load, provided that the stringers themselves are of sufficient buckling resistance. Failure — due either to flexural buckling of the complete panel or to some other mode of stringer failure — can occur at a load substantially in excess of skin buckling. Behaviour of this kind is commonly found in very light structures for which it may be desirable to concentrate the load carrying capacity in certain discrete members, with a minimum gauge skin in between. However, a post-buckled design may also be preferred in rather more heavily loaded structures, in an attempt to reduce the loss of efficiency in a practical design when some restriction on, say, minimum stringer pitch is imposed. The purpose of the present series of tests is to investigate the post-buckled efficiency of a particular family of Z-section stringer-skin panels, of a design representative of current practice, with a stringer pitch chosen to be close to one-third of the effective panel length.

A general review of the state-of-the-art in relation to stability augmentation in aircraft design, with an attempt to produce a co-ordinated view on the philosophy of its application, is something that I have long felt I should like to see done—but not by myself. My initial reaction on being asked to present such a paper was that this would better come from those concerned with the development of auto-control systems, but on second thoughts, there appeared to be some merit in considering the situation from the point of view of one concerned with the more basic aspects of aircraft handling and operation, putting the emphasis, therefore, on what is required or desirable in these respects, rather than on how it might be achieved. This, then, is my first aim; to consider various possible areas of application of stability augmentation, and advanced control techniques, to aircraft design; my survey will not attempt to be comprehensive but rather, selectively illustrative; it will, however, extend out beyond the confines of pure aircraft design, to externally guided aircraft flight, and in particular automatic landing.

In an effort to increase the air-breathing endurance capability of current hypersonic research aircraft (i.e. X-43, 7 seconds; X-51, 5 minutes), the authors have explored the technical and operational solution space for a 30 minute cruise endurance demonstrator operating in the Mach 6 to Mach 8 speed regime. The focus of this activity has been on exploration of the available solution space through a unique screening process to assess the implication and interplay between the (a) mission, (b) baseline vehicle, and (c) operational scenarios. This study concludes that an air-launched, liquid hydrogen fuelled, 30 minute duration Mach 6 demonstrator (with 10 min Mach 8 capability) provides the largest feasible solution space of the trades examined (i.e. largest design margins, lowest technical risk) when compared to a kerosene-powered equivalent.

Vortices are of interest in many situations in fluid mechanics. One type of vortex with which the gas turbine designer is concerned is the line vortex springing like a miniature tornado from a point on the ground (or from a nearby aircraft surface) and entering the engine intake. It is possible for these vortices to suck stones up into the engine (Refs. 1, 2) and also to reduce the compressor surge margin (Refs. 3, 4). They are unsteady, in that their point of origin wanders about and so does their point of entry into the intake. This unsteadiness makes it very difficult to measure them, and so far no one known to the author has reported measurements of ground vortex strength, in the course of several investigations of the phenomenon (Refs. 1-3, 5-8).

Aircraft full-scale fatigue tests are expensive and time-consuming to conduct but are a critical item on the certification path of any aircraft design or modification. This paper outlines a proposal that trades cycling hours for increased detail in the teardown of a metallic test article. A method for determining the equivalent demonstrated crack size (and crack growth curve) at the mandated test life utilising the lead crack framework is demonstrated. It is considered that the test duration can be significantly reduced, whilst still achieving all the desired outcomes of a certification program.

The attitude dynamics of a spinning axi-symmetric satellite, free to librate in roll, is studied using the WKBJ method. Applicability of the method to the linearised equation of motion is first verified. To facilitate the evaluation of the WKBJ solution and to make it more amenable to the phase space analysis, second order terms in eccentricity are neglected. The form of the solution suggests the presence of phase and amplitude modulation effects for non-circular orbits. The comparison between the WKBJ analysis and ‘exact’ numerical solutions showed that the approximate analysis predicts the period and amplitude of motion with an accuracy adequate for the preliminary design purposes.

From time to time w.e hear of mysterious engine failures, sometimes resulting in forced landings, in which the engine is reported to have gradually lost power until it was ticking over or had cut out completely. This may have been accompanied by sticking of the throttle, so that the pilot was unable to control his engine, and by rough running. Full power is usually recovered at lower altitudes or after landing, and when the engine is run up no defects can be discovered. At certain times of the year similar symptoms have been observed in the case of engines running on the test bed.

Tetraethyl lead is a constituent of most fuels of high anti-knock value, but such fuels cause serious corrosion of magnesium-base alloy tanks and may completely penetrate them in a few months. No work on the mechanism of this attack has been published and no satisfactory method for protection exists, so that magnesium-base alloy tanks cannot be used for leaded fuels. Since tanks constructed from an ultra-light alloy would be of advantage for aircraft, experiments have now been carried out to elucidate the mechanism of their corrosion, this work representing the first stage of an attack on the problem of providing protection against such corrosion.

In writing this essay on rotorcraft I have chosen to confine my interests to the flying machines themselves, their development and the pressures that are shaping their future.