I Consider it a great honour to be invited to deliver the First Lanchester Memorial Lecture, which, according to the instruction received from the Secretary of the Royal Aeronautical Society, should deal with Lanchester's personality and achievements. It is also a great pleasure for me to recall my personal contacts with this great man. On the other hand, I am not quite sure whether the decision of the Council, choosing me as the first Lanchester Lecturer, was really a wise one, since I am not in the best position to present a full biographical sketch of Lanchester. Somebody more familiar with Lanchester's automobile work, as, for example, Sir Harry Ricardo, would be more able to present a full picture of Lanchester's achievements. I must, therefore, restrict myself essentially to the treatment of Lanchester's contributions to the sciences of Aerodynamics, Flight Mechanics and Operational Analysis.

From time to time, both military and civil aircraft have had a change of power plant to meet special circumstances but in all cases considerable redesign has been necessary and I know of no instance where it has been done in the field by means of a “ modification kit.” It has become quite commonplace to do so for test purposes, that is to make the aeroplane a flying test bed. Douglas DC-3 aircraft have been fitted with Darts and Mambas, Varsity with Elands, Canberras with Olympus and many others.

Kinetic heating, which is associated with supersonic flight, is probably the greatest challenge which has confronted the structural engineer, since the design and analysis of affected structures requires a radical extension of current practice. For example, the laws of heat transfer and the effects of high temperature on structural materials become important factors in structural analysis. To obtain a clear appreciation of the situation it is therefore necessary for the designers of the structure to become familiar with these factors, together with certain aspects of boundary layer theory.

Improvements made to the aerodynamic characteristics of the wing of the Avro CF-100 Mark 5 aircraft are discussed. Modifications to the wing included increase in aspect ratio, addition of vortex generators, and deflection of trailing edge plain flaps. The effect of flap deflection and addition of vortex generators on the aerodynamic characteristics of the wing are shown to be closely associated with interaction of the upper surface shock wave with the boundary layer. Performance gains were demonstrated at high subsonic speeds at high altitudes. Vortex generators improved the buffet boundary, whereas flap deflection both increased aircraft ceiling and improved buffet boundary.

Before enlarging on the main subject of this paper, it will be helpful to clarify some fundamental conceptions of various rotor drive configurations.

In the past the original shaft-driven helicopter presented two major problems to the designer. These were first: the necessity to choose between either some torque balancing device or a multi-rotor layout and, second: the necessity of a large reduction gear box, the weight of which seemed to become prohibitive with increasing all-up weight of the design. Big helicopters with either single rotor/tail rotor configuration or multi-rotor configuration, are flying successfully and prove that these afore-mentioned problems, although still in existence, were mastered in an admirable way. Nevertheless, in the old days the words “ tip. drive ” had a magic sound to the harassed designer.

The Nature of the flow in the exhaust pipe of a turbo-charged two- or four-stroke cycle engine is in general so complex that practical tests on running machinery are necessary to compare the merits of one exhaust system with another. The analysis of the results of these tests is rendered somewhat difficult by the lack of reliable methods for measuring accurately the transient temperatures in the exhaust pipe. Indicator diagrams have therefore to be used in conjunction with empirical methods for computing the exhaust energy, these methods being associated with the measured exhaust pyrometer temperature. In calculating the theoretical possibilities of different exhaust pipe configurations for four-stroke cycle engines Jenny has suggested that the total energy was the sum of the internal and kinetic energies of the gas entering the pipe. In the present treatment it is suggested that a better criterion is the enthalpy available if the gas expands isentropically from stagnation conditions to atmospheric pressure, the justification being that this would be the energy utilised in the turbine.

For a Flat Surface at zero incidence in a deep uniform stream, the total frictional drag F per unit width of the surface can be calculated from the well known equation

Using the momentum principle in the usual way, it can be shown that when fluid is added locally to the flow through the surface, the total frictional drag F1 is given by