The discussion generated by the Roskill Commission and by airport planning inquiries in different parts of the United Kingdom has increasingly emphasised that airports are merely a sub-system within a larger system. They cannot be planned and developed except with reference to the other elements that make up that system. There are essentially four critical elements:

1. (i) The passengers or goods requiring transport by air.

2. (ii) The physical, social and economic environment around the airport.

3. (iii) The airport itself.

4. (iv) The aircraft and the airlines which operate them.

The total system is concerned with enabling passengers and freight to travel by air in order to reach a different environment.

Despite it being 19 years since Major Halford died, his influence is still felt at Rolls-Royce Small Engine Division, (formerly the de Havilland Engine Co Ltd) which indicates the stature of the man. One way that his influence is felt is that we still have some 3000 Gipsy engines in service. Considering that the first were delivered in 1926 and production stopped in 1964, he certainly had hit upon a good formula. As Mr. Perkins said at the last Halford Lecture, Halford was really as keen on doing the biggest engine in the world as on the smallest, so we cannot claim to be following a trail blazed in that direction. He was, however, very keen on the demonstration method of launching engines, and was good at getting something together very quickly to prove if he was on the right track and to “cut the cackle”.

In 1929 when I was a young schoolboy in York, I was fortunate to become one of a small band of nomadic gliding enthusiasts centred around a most enterprising chap called Percy Watson, who had built himself a German Zoegling training glider above his chemist's shop in Micklegate. Each weekend we flew this machine — on which one sat in the open with an awe-inspiring view of the ground—from a wide variety of hills and precipices in the country to the east of York in the direction of Scarborough and Whitby.

In 1936, as a result of this exciting and sometimes quite terrifying activity, I joined Slingsby Sailplanes at Kirbymoorside, where I became happily involved in the design and development of Kirby Cadets and Tutors and the like. It was a most satisfactory occupation for a young chap dedicated to gliding and in consequence I developed a love of the wolds and moors of East Yorkshire from Sutton Bank to the sea, which continues to this day.

When a powerplant air intake is mounted close to an aircraft wing or body the possibility exists of it ingesting part of the boundary layer formed on the adjacent surface. Even if the boundary layer is not ingested directly, the spillage flow from a boundary layer diverter may under some conditions affect the main intake flow. In full-scale free-jet tests of an intake or powerplant it would be desirable to represent any adjacent surfaces, but usually the size of the test facility is insufficient to allow this.

This note describes the first tests of a device, developed at NGTE, which at supersonic speeds generates in a short axial distance a layer of low energy air with a pressure distribution approximating to that of a “natural” turbulent boundary layer.

Most service failures in fatigue start on a free surface, as in many cases the most severe stress conditions exist there and are of a bi-axial stress nature, such as a drive shaft under combined bending and twisting. This particular case of multi-axial stress fatigue, because of its importance in design, has seen considerable investigation, although several aspects of the stress situation complicate the analysis of the test results with regard to the development of a general criterion of fatigue failure under multi-axial stress. The principal stress axes rotate with variations in the ratio of bending to twisting and the shaft is subjected to a stress gradient. Only the extreme portions of the shaft in the plane of bending are under the maximum bending stress, whereas the complete surface of the shaft is subjected to the maximum torsion stress.

In the modified free-streamline theory for the separated flow past bluff bodies due to Roshko, the velocity on the separated free streamlines is expressed as

Uv=kU0,

where U0 is the velocity of the undisturbed stream and k is a constant. If it is assumed that the pressure on the base of the body is uniform and equal to the pressure on the free streamline, then application of Bernoulli's equation leads to;

k =(1-Cpb)½,… (1)

where Cpb is the base pressure coefficient.