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.

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.

In trying to decide how best to lay out a paper for this Symposium one is conscious of a great deal of information lurking in the back of one's mind, resulting from the sort of discussion that we all have after flight, or on those frequent occasions when the weather or other exigencies delay us in our task, but I wonder just what real value would be served if too many of our contemporary problems were to be aired in public? I have no doubt that before the day is out a fair amount of soul searching will have to be done on all sides, but particularly at this time when, for one reason or another, the order books for significant British aeroplanes are far from full, I think it is a time to discuss our problems freely, but with a positive objective in sight, the furtherance of British Aviation in the world. If the symposium has brought people together who do not frequently meet “in mass” it could be that there might begin a better understanding between us, in which case our time today will have been well spent.

The Airline Pilot has little to do with Flight Testing for Certification, in fact, apart from a few specialist pilots in the airlines the average airline pilot takes no part in the Flight Test Programme.

Once an aircraft has been certificated, however, the airline pilot spends more time on the Flight Deck and has longer to experience the shortcomings of the Certification Programme than anyone else. He is then the Consumer, the man who spends hours with an expensive piece of machinery strapped to him and who suffers over a long period of time any cockpit design defects. For that reason a large part of this paper will be devoted to, I hope, useful criticism of Flight Deck Layouts as they affect the operating crew member.

I am More than a little nervous standing here, because I am the non-expert in a room full of experts, or if you will, a single sheep among a number of wolves.

I have been asked to represent the fare-paying passenger's point of view to a symposium of technical people, and as such I want to make it clear at the outset that what I am going to say is opinion, not entirely uninformed but certainly not expert. If out of what follows I am wrong from time to time, then I hope you will understand that it is not a deliberate attempt to make noise for noise sake, but is really representing the thoughts of the fare-paying passenger.

At the outset, I must make it quite clear that any views or opinions expressed are my own and are not necessarily those of either British European Airways or the Flight Safety Committee.

In this paper, I have attempted to discuss some of the problems which face those whose task is to obtain and to disseminate safety information. At the end, I have posed a number of questions which I believe are relevant and should be posed, and which Harold Caplan will take up in his subsequent discussion of the legal problems.

Air Safety is essentially the prevention of accidents by minimising the risk of encountering foreseeable hazards and the consequences of unforeseen situations. Thus the dissemination of air safety information is simply the spreading of accident prevention material. It is undoubtedly best achieved by a sharing among all concerned of the lessons learned from their incident and accident experience. This activity is one that has to be shared by operators, flight and ground crew, air traffic control, the designers and makers of aircraft, engines and equipment, and regulatory authorities.

Hugh Gordon-Burge has stated with clarity and force two of the salient problems in air safety work—that of obtaining information on accidents and incidents and that of disseminating the useful results after investigation and analysis.

He has also asked a number of pertinent questions to which I will try to provide some answers. As a basis for further discussion I also offer some tentative solutions to certain of the problems he has identified.

The views expressed are entirely personal.

Using television as an instrumental aid, light helicopters can be hovered with considerable accuracy above a known ground point at altitudes of the order of a thousand metres above ground level. The image from a vertically-aimed ground-based television camera is transmitted to the helicopter and displayed on a receiver placed in front of the pilot, who uses the image of the helicopter for guidance to the hover point. With this system, the hover point has been maintained within ±1.2 m (4 feet) for periods of up to 2.5 minutes at 1200 m (4000 feet) above ground level.

The natural frequencies and modes of vibration of a structure may be obtained more or less directly from experiments. The generalised masses and stiffnesses, however, are usually obtained indirectly from experimental investigations of the dynamic behaviour of the system. One of the techniques widely used for this purpose in the aircraft industry is known as the method of displaced frequenciesm.Stated briefly, the method consists of observing the changes in the natural frequencies caused by the addition of one or more small masses to the vibrating system.

In his paper, Mahalingam describes a simple receptance approach to the displaced frequency method, and shows how (in the simple case where the added mass affects the kinetic energy of one co-ordinate only) this can be applied in the determination of corrected generalised masses. A method had been propounded previously by the present author, and this accomplished the generalised mass corrections by a procedure related to the Collar-Jahn Method for the correction of an approximate set of eigenvectors.

At first sight, the methods of refs. 1 and 2 appear very different—the first being based on dynamic flexibility relations and the second on dynamic stiffness relations. Indeed, the final forms of the equations for the corrected generalised inertias obtained from the two approaches appear radically different, and it is by no means obvious that the two methods will, in general, produce identical (or nearly identical) results.

This note considers the buckling of a circular lenticular plate subjected to a temperature which varies parabolically in its plane. The novel feature in the analysis is the determination of the stiffening effect due to the prevention of deflections, but not slopes, along a diameter.

Fluid motion in an annulus is described, in the absence of radial velocity, by the simple radial equilibrium equation. This equation is used to describe the flow in an axial turbomachine some distance ahead and behind the rows of blades, where radial displacements have already decayed.

In the neighbourhood of and between the blades the fluid motion is far more complex than the flow in the radial equilibrium condition. Most of the difficulties of the real problem can be overcome by introducing the actuator disc mathematical model. The actuator disc divides the complex flow field into two simpler fields, each free from blades, i.e. a simple annulus. The equations of motion in each field are easily linearised by posing some particular restrictions concerning the velocity profiles and by conceiving the velocity as the sum of the radial equilibrium solution and of small perturbed quantities. These are radial and axial perturbation velocities vanishing far from the actuator disc, and are given by a perturbation velocity potential.