One of the few privileges the public lecturer has is to divide all mankind into two classes according to his prejudices, and this I intend to do: on the one hand those restless souls who constantly strive for innovation and change; on the other the great mass of humanity who resist and even resent any disturbance of the even tenor of their ways.

The first fish-like beast that crawled out of the primeval swamp on to land must have had something of this spirit of change and adventure. And from the dawn of history the rare men with these characteristics have provided the leadership and sparked the changes that have been at the heart of human progress.

Cost estimating is all too frequently thought of as a necessary but dull and uninspiring task better performed by persons who are either incapable of, or uninterested in, wrestling with the important and exciting issues of the day. Even with the current concern for the economic implications of choice, cost estimating is only beginning to be accorded its rightful place in the decision making process. The reasons for this are many, but the most significant is probably a general lack of awareness of the potential benefits that are to be realised. One place where cost estimating has, in recent years, been allowed to play its proper role is in military long-range planning, and the rewards have been great. The general philosophy of the military planner and the concepts and methods of the cost estimator that have permitted this to happen are discussed. In the second part of the paper, an example of a cost analysis in support of a military planning problem is presented. The example points up the fact that cost estimating can be an intellectually stimulating activity worthy of the application of the best analytical skills available, and that it can provide useful answers to difficult and important questions even when uncertainty is great and quantification is difficult. Even though the discussion in ‘this paper is based on a military long-range planning application, the concepts, methods and techniques that have made success possible there, have much more general implications. Believing this, it is is hoped that this paper will serve to further the awareness of many, and stimulate some, to seek out the important benefits to be derived from a less traditional approach to cost estimating.

When digital computers first became available many of us expected that they would have an early and significant impact on engineering design. This did not happen, and the reasons why it did not are worth examining. For one thing, the early computers were not nearly large enough; engineers do not build things out of spheres and parallelograms as mathematicians do, and quite a lot of storage space is needed to describe a typical problem in engineering design. Unfortunately, the big computers when they came were so expensive that it was not considered economic to allow users to handle them personally, and batch-processing techniques were introduced. The result was to create a barrier between the computer and the design engineer, and to make it impossible for him to get results of any kind without a delay amounting to a few hours at the very best, and often to much more. Emphasis in fact, was put on the efficiency with which the central processor of the computer was used and no regard at all was paid to the efficiency with which the users—in this case programmers and design engineers—worked. We are on the threshold of a development which, there is every reason to hope, will change the situation radically.

This is the Age of Space Flight. Satellites orbiting the earth are the heralds of more spectacular demonstrations to come. “Man in earth orbit” is the prologue to manned missions in the alien environment of lunar space.

Basically, the objectives of the US space programme are to:

• 1. Expand human knowledge of atmosphere and space.

• 2. Improve the use, speed, performance, safety and efficiency of aeronautical and space vehicles.

• 3. Develop and operate vehicles capable of carrying instruments, equipment, supplies and living organisms through space.

• 4. Study the potential benefits of space activities for peaceful and scientific purposes.

• 5. Preserve the role of the US as a leader in aeronautical and space science and technology, and in the application thereof to peaceful activities.

This subject, even as it applies to those areas which are the direct or partial responsibility of the test pilot, is a comprehensive one, and it is not intended to embrace it completely. Specifically this paper will touch only on the area in which the pilot is principally involved. Further, it is not the intention to catalogue the tests required for certification or to describe all of them in detail, but rather to discuss the whole certification process in more general terms.

The purpose of Certification is to establish a minimum safety standard, but when forming that standard, sight cannot be lost of the feasibility of achieving it, both practically and commercially. Inevitably, therefore, the discussions or arguments that arise over establishing the standards against which aircraft are going to be assessed must centre around the problem of where the balance between safety and cost should be struck. As previously implied, absolute safety is not only probably impossible to achieve, but quite clearly commercially impractical. The constructor's task must be, therefore, a process of resolving the often conflicting ideas of the various bodies and agencies that attempt to define the “balance” and within that definition offer a commercially attractive aircraft. If he strays widely from the prevailing definition, even in the interests of increased safety, he is in danger of pricing himself out of business. This fact is rather obvious, but no excuse is given for stating it since it is thought to be so fundamental to the subject under discussion, and one that is often overlooked, particularly perhaps by those who are not so involved with the day-to-day operation of aircraft.

The engineering designer may not always be aware of the paramount importance of being able to sketch his ideas as a means of communicating his plans.

An example illustrates the point that drawings, graphs or diagrams convey concepts more easily than a table of figures. Table I gives a series of X and Y values describing a well-known contour, but it is not easy to determine the shape except by plotting the points. One can appreciate at a glance at Fig. 1, however, that it is a well-known shape.

Although the drawing is very graphic, the term graphic will also be taken to include alphabetical and numerical records for the purpose of this paper.

Before detailing the value of non-destructive testing in the aircraft industry, it seems best to explain aircraft structural design philosophies as they affect NDT.

Airworthiness and weight-saving are two over-riding factors in aircraft design. The important parameter from an economic standpoint is the weight. Fig. 1 shows the value of weight saving for a civil aircraft operator in £ per lb with typical values going up to £100 per lb per aircraft per year. (This figure shows the actual financial saving associated with the reduction in operating economics due to the lower weight.) But the vulnerability of an aeroplane in any failure case makes safety a paramount consideration. To save weight, design factors on aircraft are very low.

It is a privilege to pay tribute through this Cierva Memorial Lecture to a great pioneer and an honour to do so in this, the Society's Centenary Year. In 1918, when 24 years of age, Cierva designed and built a three-engined aeroplane which stalled during a turn and, after spinning, crashed. He recognised the limitations of the conventional aircraft and turned to the rotating wing.

Westland's association with rotary wings began with the five-seater 600 hp Cierva C.20, built in 1934. Their first series production rotorcraft, the S.51, to the design of Igor Sikorsky, came some 14 years later. With the passage of further time, bringing some successes and some frustrations, a sound foundation has indeed been laid for future progress.

Although the Hatfield tunnel has been doing some useful testing for just over eighteen months, the experience so far obtained is still limited as each new model brings its own special problems. It is perhaps still too early to give an account of the experience obtained, but because of the interest in this tunnel it was thought that an account, even incomplete, would be useful.

Almost every facet of experience so far obtained is related to some of the special design features of the tunnel and I propose to review some of the problems encountered during the design stages of the tunnel dealing with these design features, before reviewing the actual model testing experience.

A review of some methods of obtaining augmented lift coefficients in aerofoil sections precedes a description of lift by circulation control by blowing. The basic aerodynamic characteristics are considered as a prelude to a comparison of the merits of their application to helicopter rotors.

In calculating the performance of a helicopter rotor which uses high lift coefficients, the determination of the induced power has demanded an extension of the performance estimation curves normally used. A theoretical model has been developed to calculate the induced power factor which suggests a large increase in this parameter for rotor thrust coefficients above the current helicopter operating regime. Experimental results up to thrust coefficients of 0·1 which confirm the theoretical results are presented.

Some tentative ideas on the application of circulation control to produce a high speed helicopter are considered.

I am deeply conscious of the honour to the New Zealand gliding movement and to myself as its representative to be asked to deliver the First George Bolt Aviation Memorial Lecture. George Bolt was one of the first New Zealanders to construct and fly his own glider in the early years of this century, and for the remainder of his life he retained an intense interest in gliding, even when deeply involved in increasingly complex powered aircraft. He agreed to become the first Chairman of the Technical Committee of the New Zealand Gliding Association, and as such helped the movement in its struggles to get back into the air after the Second World War. It is thanks to him that the Association was established on a sound technical basis, as the first post-war Director of Civil Aviation made it clear that the New Zealand Gliding Association would not be recognised until a competent Technical Committee was formed.