Some interest was aroused in the middle of the eighteenth century when an Italian visitor to London exhibited a colourful flying machine which he promised to demonstrate. A full but comparatively little known report was published by the triweekly Whitehall Evening-Post in the issue dated 3rd-5th October 1751. Soon after its appearance, another Italian plagiarised it, sending a translation to a friend in Italy in the form of a letter, dated 18th October 1751, which purports to be an eye-witness account. This may have been published in Venice in the same year, as a fly sheet. In 1752 the letter and the flying machine were mentioned in a collection of noteworthy events, and in 1753 it was given cursory attention by Clemente Baroni Cavalcabò, in his famous book about the inability of demons to carry men through the air, The celebrated art historian Francesco Milizia included a brief summary in his biography of Paolo Guidotti, the painter and would-be aeronaut, and more recently the plagiarised text has been noticed by Italian historians of aviation.

Any aero engine designer works against a background of a list of general desirable features for all engines of:

In the helicopter business however, the engine designer is faced with a real dilemma. On the one hand there is the desire to produce an engine which has as wide an application as possible, (i.e. turboshaft, turboprop, turbofan, APU, industrial power generator, marine traction etc) and this produces a basically low cost, high volume, production flow provided that the required changes in the engine configuration are kept to a minimum.

This paper deals, in the main, with aluminium alloys and steels that are currently available on a commercial basis or are likely to become available in the near future. It highlights the more significant improvements made during the past two decades.

Aircraft structures have been built predominantly of aluminium alloys since the Second World War and, although certain improvements have been made over this period, the alloy systems used have changed little essentially because the alloys available have been limited by the solid solubilities of the selected solute elements at safe solution temperatures. The slow but certain development of novel production routes including fibre and whisker reinforcement of metals, powder production and rapid solidification techniques will circumvent this limitation by the turn of the century.

There are two main reasons for the modern resurgence of interest in airships. The first is that it can have a greater endurance than any other flight vehicle. This makes it particularly suitable for such offshore tapestry duties as fishery patrol and oilfield surveillance. The second is that it does not require power to sustain lift. It can thus transport a given load with a low expenditure of fuel which is continually rising in price.

The College of Aeronautics has a considerable interest in composite materials, and in their application in particular to aerospace vehicles, over a number of years, and during this time we have conducted several research programmes on these types of materials.

During recent years, an area of research which has attracted our interest is in the application of composite materials to light aircraft, forming part of a more general study of light aircraft which has resulted in our constructing and testing aircraft in this category on two occasions in recent years.

Some of the work on these programmes has been conducted by students at Cranfield studying for higher degrees, and I acknowledge my indebtedness to them for some of the results presented in this paper.

The developments in the use of composite honeycomb in passenger aircraft structures has been growing rapidly over the past ten years. Starting with its use in the semi-structural internal use as a flooring material such as the cross plied UD glass-nomex cored floors of the wide body jet aircraft — 747 — L1011 and DC10, to the external uses for control surfaces, fins, undercarriage doors, engine pods, etc, and the ultimate all-composite fuselage of the LearFan project.

The progress in the light aircraft field by comparison, is almost non-existent, the major use of composites is restricted almost entirely to the manufacture of sailplanes and the majority of these use foam stabilisation rather than honeycomb.

Throughout its existence the organisation now known as British Aerospace, Warton Division has been primarily concerned with the design and manufacture of advanced combat aircraft. Often it is in this class of aircraft that the advantages of developments in structures and materials are first realised on a production basis.

This paper briefly describes some of the currrent involvement of Warton structural engineers in material selection, technology demonstrators and future projects for the next generation of combat aircraft.

The theory of optimal flight paths goes back to 1951, when Tsien and Evans found the optimal thrust program for a vertically ascending sounding rocket. Hibbs, in 1952, solved the problem of the optimal burning program for horizontal flight of a winged, rocket propelled vehicle. Miele has carried out much work in this field, mostly using*the assumption of constant thrust, and working without the aid of a digital computer, (which is necessary to achieve results). Reference 3 gives a summary of early work in this field.

Recently, the problem of optimal climb paths of a ballistic rocket, away from the vertical, has been shown in Ref. 4 to have a simple analytic solution. The problem of a winged supersonic rocket missile, assuming the thrust acts along flight path, has been solved in Ref. 5.