Ladies and Gentlemen, tonight we pay homage to Frederick William Lanchester, Doctor of Laws, Fellow of the Royal Society who, having become interested in mechanical flight at the age of 21, while studying at South Kensington in 1889, entered the field of aeronautics in 1892 and continued to aid its development until his death in 1946. His great contributions to aeronautics were the discovery of the theory of the vortex motion of the lifting wing and that the key to successful flight lay in reducing the skin friction, which was far from being the negligible quantity that others such as Langley, whose name is forever remembered through NASA Langley Field, had stated earlier. All this was in 1893 to 1894 some ten years before the first flight of the Wright brothers. When asked later how he had successfully derived his great and momentous theory Lanchester simply stated; ‘it was a matter of logical deduction helped by experiment’. He vigorously defended his work as not being empirical but was soundly based on hydrodynamic theory.

The unique aerodynamic features of the highly coned propeller, with cyclic and collective control of blade pitch, are discussed in simplistic terms.

The configuration poses severe structural design problems and, while fibre reinforced composites fabrication might enable these to be surmounted, there will be weight penalties in overcoming them that will limit potential applications.

No outstanding prospect for the propeller is identified, but specialised applications may merit a closer scrutiny of the concept.

It has always been important for military commanders to be able to rely on their equipment being available to them during a conflict. Some recent published figures, however, showed that two modern fighter aircraft were only available for missions for 47% or 56% of the time.

A simple operation simulation model was derived to show an aircraft's sensitivity to the main availability parameters. This model can be applied to any aircraft type provided that the necessary inputs can be calculated. The simulated operations were as realistic as possible, although many assumptions had to be made.

For reasons of national security it was not possible to relate this study directly to any current service aircraft, so a design project study has been used as the baseline aircraft in the simulation model. This aircraft was the 1980 Mini-CAS, developed at Cranfield Institute of Technology. This was used because all the necessary data were available or could be estimated with reasonable confidence and also the operating conditions are comparable to a number of current service types employed in the Close-Air-Support role. Thus the simulation was kept realistic and the results and conclusions are directly applicable to real and projected designs. Subsequent work checked the validity of the model by simulating an A-10 exercise and Sea Harrier operations in the Falklands conflict.

The Operations Simulation Model proved to be a satisfactory means of assessing the effectiveness of a force of aircraft under war-time conditions. It was far more flexible than the Availability and Mission Readiness equations commonly used to compare the in-service performance of aircraft and highlighted areas where resources could best be concentrated to improve availability. Further improvements are necessary however, to take account of spares shortages and the effect of adverse weather.