It is a great distinction and a highly esteemed honour to be privileged to read the forty-seventh Wilbur Wright Memorial Lecture. It is also a distinct personal pleasure to be here. Over the past 15 years I have made periodic trips to England to visit the aircraft companies, to witness the spectacular Farnborough displays of the S.B.A.C. and to attend the Anglo-American Conferences of the Royal Aeronautical Society and the Institute of the Aeronautical Sciences. This has afforded opportunities to observe and admire the rapid progress you have made in aeronautics, the brilliant achievements of British engineers and scientists and, more importantly, the chance to make and deepen warm and valued friendships. The joint meetings of the Society and the Institute are proving to be fruitful ground for the exchange of ideas and for becoming better acquainted. May I express the sincere wish that I shall have the pleasure of welcoming many of you to the Seventh Anglo-American Conference which will be held in October 1959 in New York.

So much has been written, both of fact and fancy, about satellites and space travel in the past few years that the selection of material suitable for presentation to the members of a learned Society concerned mainly with purely aeronautical matters is a hazardous and difficult task. I propose in this paper to tackle it by restricting the subject severely to a description of the general characteristics of near earth satellites and the scientific exploration made possible by their use as observing platforms. The later sections of the paper have a bearing on the possibilities and engineering problems of space probes and space travel; I leave it to others to speculate on the likely time scale and types of such activities and attempt instead to make sure that the basic factors involved are made reasonably clear. To set the background it is important to review briefly the actual practical achievements up to the present time.

The tendency in the past has been to assume that when wakes or non-uniform total head profiles are fed into an axial compressor then substantially constant static pressure prevails at the entry, the variations in total head appearing as variations in velocity. This variation in velocity causes variation in incidence on the early stage blade rows and thus can give rise to excitation of blade vibration. This assumption is implicit, for instance, in References 1 and 2, but we think has been a common assumption by most of the people working in this field.

Where the compressor is fed by a duct of substantially parallel walls for a reasonable length ahead, such an assumption appeared justifiable. Such a duct when given an air flow test with its outlet discharging, for instance, to atmosphere instead of to the compressor, then the distribution assumed would normally be obtained and in fact many surveys of such ducts have been represented in this fashion. The object of this note is to show that, in fact, this distribution will not normally occur when the compressor is present and we may normally expect much more nearly a constant velocity into the compressor with attendant static pressure distributions to match with the total head variations ahead of the intake, with of course, the attendant curved flow to support the static pressure gradients.

I should like to thank Mr. Hafner for his paper on “ Safe Mechanisms ” published in the May Journal (p. 273). There is much scope for thought and invention along the lines he suggests and such thought will result in increased safety.

In Section 3.1 on page 276 “ Safety Standard,” it is suggested that accident statistics should be quoted on an hourly basis and not per mile. A man expects to live three score years and ten; it is, therefore, the risk of spending a proportion of this time in a given occupation which is significant. It is then possible to compare the relative risks of lying in bed, train travel, air travel, space travel and so on.

With modern air liners flying at altitudes of 20,000 ft. or more, the question of passenger safety in the event of pressure cabin failure has become a real problem. Should failure occur, the Captain of an air liner flying over the sea, or difficult country, would have to decide between exposing his passengers to the anoxic effects of high altitude or of accepting the increased fuel consumption which would result from flight at a lower altitude.

An Emergency Passenger Oxygen System to enable the flight to continue at an altitude where fuel consumption would not be excessive has been developed recently by the Walter Kidde Co. Ltd. in conjunction with the Scott Aviation Corporation of America. The Mask Presentation Units included with this system are unobtrusively located in the luggage rack and, in the event of pressure cabin failure, an oxygen mask is automatically presented in front of the head of each passenger. It is then only necessary for the passenger to pull the mask on to his face to obtain a supply of oxygen at sufficient flow to safeguard him until the aircraft has been brought down to a lower altitude. In addition, each Presentation Unit includes an attachment point for medicinal or therapeutic oxygen, which is independent of the emergency system, and from which a supply is always available. Leakage from these points when not in use is prevented by self-sealing outlets. The Presentation Units are easily removable for overhaul purposes, and can be adjusted for a change of seat layout. A manually operated cock enables a crew member to operate the system if necessary. Fig. 1 illustrates the system in use.