Gliding as a sport dates from the early nineteen twenties when German pilots, banned by the Treaty of Versailles from constructing or flying powered aircraft, turned their attention to constructing sailplanes. Their progress was remarkable and, after visits by some of their best pilots to England in 1929, many clubs were formed here together with an association of clubs, the British Gliding Association. Many of these clubs lasted only a few months but by 1937 a few were in a strong position and in November 1937 Squadron Leader (now Group Captain) Buxton gave a lecture to the Society reviewing developments up to that date. Developments in gliding are well recorded in the Journal of the B.G.A., Gliding, and in the other aeronautical periodicals, but it is proper that the Society should record periodically progress made in this branch of flying.

Compared with the general advance of aeronautics in the past decade, or indeed with sailplane development in the 20's and 30's, progress in sailplane design has recently been very leisurely. This is due in part to the fact that there is less scope and partly because little effort has been expended. The most important advances in the art have been in the understanding and use of meteorological conditions which make soaring flight possible; sailplanes good enough for the purpose have existed.

Before the Second World War the main design impetus came from Germany and Poland and in most current designs the German influence is still strongly evident. Since the war there have been outbreaks of activity in Switzerland (W.L.M.I., Moswey), Canada (where Shenstone and Czerwinski have inspired designs at Toronto) and in the United States. The total effort has not added up to that in pre-war Germany.

An experimental determination of the relation between the rate of sink of a sailplane and its air speed is of interest both to the designer and to the pilot. This paper describes tests made to establish this relation for the Slingsby Sky. During the tests, the aircraft was flown in a series of “ partial glides ” at constant speed, while a camera looking over the pilot's shoulder photographed the altimeter and A.S.I., together with a slip indicator and a clock. From an analysis of the photographic recordings, the mean air speed and the rate of sink during each partial glide can be determined; a large number of such results enables the relation between air speed and rate of sink to be established. The final results show that a considerable improvement in high-speed performance can be achieved if the aircraft is fitted with a long skid instead of the short skid and large fixed landing wheel; the superiority of the Sky over the Weihe for competition work is demonstrated. Sources of error in the results are discussed; it is shown that the accuracy with which the rate of sink may be determined is limited by the presence of vertical air movements. Possible future trends in performance testing technique are discussed.

This report presents an abbreviated summary of theoretical studies made by a group at the Research Laboratory of Electronics, Massachusetts Institute of Technology, under contract with the Air Navigation Development Board of the Department of Commerce. The details of the analysis and the results have been treated more comprehensively in two technical reports of the Research Laboratory of Electronics.

Carving from the solid is a manufacturing process dating back many thousands of years. Thomas Moore in his sculpture “Recumbent Figure” (Fig. 1) has instanced an example to aircraft engineers of integral construction and, has even gone to the trouble of providing discreet lightening holes.

Art throughout the ages has always looked to the future and while we are still busily applauding Shakespeare and Beethoven we are often left wondering with Moore and Walton.

Aircraft engineering is very much an art but Moore takes his integral construction for granted while aircraft designers are only just beginning to wonder.

A new method of presenting the aerodynamic data for a compressor or turbine blade cascade is shown, with particular reference to flutter excitation or damping. The application of these results to wake excitation is demonstrated.

The basic equations for flutter excitation or damping are derived in the paper “The Aerodynamics of Compressor Blade Vibration” presented by H. Pearson at the 1953 Anglo-American Conference (London). No new equations are derived but the method of plotting the relevant data leads to a simpler appreciation of the criteria.

The usual method of load measurement with strain gauge load cells in a bridge circuit involves the measurement of the out of balance voltage either by the height of a trace displayed on a cathode ray oscilloscope, or the width of a band produced by a tuned galvanometer. Both involve careful regulation of the input voltage or calibration during use. The method described provides for a null balance of the bridge at any instant in the cycle of a uniformly repeated cyclic load up to 10,000 cycles per minute. An accuracy of ±½ per cent, of the capacity of the load cell is obtainable.

A method for obtaining high Mach numbers using compressed air of low pressures is described. The proposed system can be used to extend the working range of existing direct blow-down and induction facilities.

An investigation has been made to see whether a supply of compressed air of about 5 atmospheres could be used to achieve Mach numbers between 1.4 and 4.0.

The commonly used types of intermittent supersonic wind tunnels driven by compressed air are

1. (a) Direct blow-down tunnels.

2. (b) Induction tunnels.

At high Mach numbers the induction tunnel is known to be very inefficient while the direct blow-down tunnel requires high stagnation pressures.