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LAST October a paper was presented to the Royal Aeronautical Society entitled “ Practical Airscrew Performance Calculations,” by F. M. Thomas, F. W. Caldwell, and T. B. Rhines.

THE trend of design in the modern aeroplane has been toward improved performance realised through external cleanness. It is apparent that the number of essential units comprising a modern aeroplane is nearly a minimum at the present stage of the art, and it appears also that the possibilities of further striking reductions in the drag of these units, due to change in form or shape either individually or in combination, are not great.

(7) Separate Openings in the Skirt.—A number of equally spaced rectangular openings were cut in the skirt. Openings of this sort could be closed by a rotating shutter. Separate openings of this type were found to be less effective in producing flow and considerably less efficient. Such openings might be closed by doors opening in the manner of flaps. This last arrangement is somewhat less effective than trailing‐edge flaps and also less efficient. Nevertheless, doors of this type may be made to produce large increases in flow. Tests with varying number and sizes of doors disclosed that, if the doors are placed too far apart, good cooling will be obtained for cylinders immediately in front of the doors, but the cooling of the other cylinders will be much less. Therefore, two or three doors are likely to be insufficient, and the use of four or more is preferable.

THE originality of the Escher Wyss airscrew, which has been adopted by the Swiss Air Force, is based on the fact that its conception has, since its inception, taken into account all the requirements of a modern variable pitch airscrew. These conditions may be summarized as follows, that the airscrew must normally ensure automatic control at constant engine speed, adapting itself to every condition of flight, and that it should provide, when required, for operation as an aerodynamic brake, and be capable of being moved to the fully feathered position. The essentially mechanical problems, such as the anchorage of the blades in the hub and the design of the pitch control mechanism, must naturally find correct solutions to ensure reliability, together with that simplicity of control which is an essential property of all modern aircraft components.

As a result of the election held in March the Council of the Royal Aeronautical Society for the year 1939–1940 is constituted as follows:

THE medical problems of flying were first seriously tackled during the latter part of the first world war, when it became obvious that mechanical construction was indivisible with pilot performance. Research has since proceeded along two main lines: pre‐selection of personnel for flying duties and the maintenance of the physiological efficiency of flying personnel. There is no doubt that the work accomplished is proving invaluable in these times of extended air force expansion and added interest is therefore given to the report of the symposium held at Washington D.C., at which Air‐Commodore H. E. Whittingham represented Great Britain.

The purpose of this paper is to propose a solution for automating the task of matching business process models and search for correspondences with regard to the model semantics, thus improving the efficiency of such works.

A method is proposed based on combining several semantic technologies. The research follows a design-science-oriented approach in that a method together with its supporting artifacts has been engineered. It application allows for reusing legacy models and automatedly determining semantic similarity.

The method has been applied and the first findings suggest the effectiveness of the approach. The results of applying the method show its feasibility and significance. The suggested heuristic computing of semantic correspondences between semantically heterogeneous business process models is flexible and can support domain users.

Even though a solution can be offered that is directly usable, so far the full complexity of the natural language as given in model element labels is not yet completely resolvable. Here further research could contribute to the potential optimizations and refinement of automatic matching and linguistic procedures. However, an open research question could be solved.

The method presented is aimed at adding to the methods in the field of business process management and could extend the possibilities of automating support for business analysis.

The suggested combination of semantic technologies is innovative and addresses the aspect of semantic heterogeneity in a holistic, which is novel to the field.

THE remarkable strides made by designers of commercial and military aircraft during recent years have been most strikingly evidenced by the ever‐increasing performance of their products. This progress has been gained, to a great extent, in two ways: by improving the aerodynamic cleanness of the aeroplane and by increasing the specific power output of the engine. However, the successful utilisation of both methods has been complicated by the difficulty of providing the higher‐powered engines with proper cooling and accessibility while retaining the cleanness of the aeroplane. Each addition to the power‐plant output has not only further complicated that unit and made necessary more controls and accessories, but has also made the engine harder to cool. Designing the cowl to favour the cleanness of the aeroplane has often proved to be detrimental to both proper cooling and accessibility.

EVERYBODY travelling in air or water by its own power applies the reaction or “repulse” principle, that is to say, it either takes up parts of masses contained within itself or, by means of suitable organs, gathers up parts of the surrounding fluid medium and accelerates these masses at a speed greater than its own travelling speed, and this generally in the direction opposite to that in which it desires to travel; whilst in certain cases, in addition to the force produced by the repulse, a further force is obtained through the forward suction of the fluid medium. Devices intended to utilize only the negative pressure produced by suction, e.g. through lateral ejection by means of radial surfaces running at very high (five‐figure) r.p.m. have not, in spite of repeated endeavours, proved successful.

The purpose of this paper is to compare the effects of two different configurations of plasma streamwise vortex generators (PSVG), including comb-type and mesh-type in controlling flow. This is demonstrated on the NACA 0012 airfoil.

The investigations have been done experimentally at the various electric and aerodynamic conditions. The surface oil flow visualization method has been used to the better understanding of the flow physics and the interaction of the oncoming flow passing over the airfoil and the vortex generated by comb-type PSVG.

This paper demonstrates the potential capabilities of the mesh-type and comb-type PSVGs in controlling flow in unsteady operation. It was found that the vortex generated by the mesh-type PSVG in unsteady operation was an order of magnitude stronger than comb-type PSVG. The flow visualisation technic proved that only a part of the plasma actuator is effective in the condition that the actuator is installed only on a portion of the upper surface of the airfoil.

This paper experimentally confirms the capabilities of the mesh-type PSVG unsteady operation in compare with comb-type PSVG in controlling flow, whereby recommends using mesh-type PSVG in the leading edge in front of comb-type PSVG on the entire wingspan to prevent the stall.