Some of man's greatest inventions, like the wheel, have no counterparts in nature, while others are copied directly from nature but are far removed from the original source from which they were derived. The phenomenon of natural flight was, of course, the inspiration for the idea of human flight, but the man-made machines to obtain propulsion differ entirely from those of the birds.
A good many methods have been tried to provide a heavier-than-air machine with the power to leave the ground, but it was not until the arrival of the internal combustion engine that there was a prospect of success. Now we have arrived at the stage where the conventional design of this engine is being abandoned. Recently, visitors to the Museum had the opportunity of seeing how the turbo-jet engine operates in one of the latest designs, and now a new conception is being displayed to keep visitors in step with aviation progress.
This new concept is the Rolls-Royce turbo-prop engine, four of which are installed in the new Viscount airliner. The operation of the engine is clearly shown in the cut-away example on display. The operating cycle shows how air is drawn into the engine through a ring-shaped intake and led into a two-stage compressor. The compressed air is forced to seven combustion chambers where it is mixed with a low volatile kerosene and ignited. The tremendous energy thus created is utilized to drive a two-stage axial turbine. The turbine power is transmitted by a shaft to drive the compressor and then through a high ratio reduction gear to drive the propellor. The result furnishes a silent smooth flight that is almost completely free from vibration.
By way of contrast, and to show the enormous progress made in the development of power within the past forty years, an original threecylinder Anzani engine is displayed alongside the big Rolls-Royce. The tiny Anzani furnished the motive power on Louis Bleriot's famous flight across the English Channel in 1909. This narrow strip of water had been crossed by balloon in 1785, a very notable adventure, but the crossing by airplane was of greater significance because it proved the "flyingmachine" was at last a practical vehicle. The psychological effect of this flight could not be denied, and it has been selected by general consent as a landmark in progress.
The Anzani was air-cooled, but so precarious was this flight that its power was only just sumcient for the task, and it is said that had Bleriot I51