It may be asked why I have chosen the subject of instrumentation for this Folland Memorial Lecture, rather than one more closely allied to that of aircraft design— the craft of which we remember Henry Folland as a master. In part I believe the two subjects are closely related, and that a study of the way in which instrumentation has developed indicates many respects in which this development has paralleled, or depended upon, the various developments which have occurred in airframe design.

There is no indication in the admirable biographical lecture on H. P. Folland presented to this Society by his son, as to any special views he may have held on the subject of flight instrumentation. One thing is sure, however : his working life spanned the era in which there was a fundamental change in the views held by aviators about instruments.

Three qualities come to mind as seeds for success in civil aircraft engine design over the next two decades—care, optimism and judgement; care to exploit and extend the technology of the high bypass ratio fan engine, optimism to continue to seek apparently unconventional concepts, and judgement to identify the opportunities when each should be applied.

This paper accepts this definition of the engine designer's choice and reviews a range of possible trends, some more likely than others. It is in two parts. The first, entitled ‘Conventional Engines', concentrates on the family of high bypass ratio single stage fan engines which has become established as the preferred design for application to aircraft cruising at high subsonic Mach numbers.

This paper deals with two operational aspects of civil aircraft design of major interest to Operators and Pilots,

1. (i) Flight Control Systems and

2. (ii) Information Requirements.

The first of these describes the problems encountered in our 10 years experience of autoflight, and the operational requirements arising from this, while the second describes the problems caused by the limitations in the availability and display of information to the pilot, and proposes improvements in three areas.

It is only fifteen years since the hovercraft principle and early configurations were first described in Ref. 1. Since then, we have seen the development of a wide range of craft and many applications in both civil and military roles.

This paper gives a brief review of the performance capability of the Mountbatten Class SR.N4 amphibious hovercraft which are currently operating on the English Channel ‘short sea’ routes and indicates the improvements anticipated from a simple but substantial lengthening of the craft. A contract has now been signed with British Rail to lengthen both of their craft, and design and manufacture work is now in progress. The first craft returns to BHC in December 1976 and will be back in service in its modified form by December 1977.

Aerodynamic properties of oblique wings have been studied intensively at NASA Ames Research Center and also by the Boeing Commercial Airplane Co. Figure 1 shows the design proposed by Boeing for a 200 passenger transport intended to fly in the transonic speed range; the design employs an oblique wing of high aspect ratio.

One feature of the oblique wing design that has not been fully documented is its aeroelastic stability. Since the oblique wing has one panel swept forward and the other swept back, it is perhaps natural to try to relate its behaviour to well known phenomena associated with conventional swept-forward or swept-back wings. This approach would lead one to expect aeroelastic divergence of the forward wing panel.