A SIMPLE COMPRESSED AIR ENGINE
Duringthe past few years model flyers in America have shown a tendency toward the adoption of compressed air engines for use in connection with model aëroplanes. Hitherto, England has been the home of the compressed air engine, where a great deal of experimenting has been carried on, to a considerable degree of success. Flights of over 40 seconds have been made with models in which compressed air power plants were used. But, however, the desire on the part of a large majority of model flyers in America to build scientific models, that is, models more closely resembling large machines, has made it necessary to find a more suitable means of propulsion; rubber strands being unsatisfactory for such purposes. Many different types of compressed air engines have made their appearance during the past few years, among which the two cylinder opposedtype is very favorably looked upon, because it is perhaps one of the easiest to construct.
To make a simple two cylinder opposed compressed air power plant, as illustrated inFigure 1 of diagram 16, it is not necessary that the builder be in possession of a machine shop. A file, drill, small gas blow torch and a small vise comprise the principal tools for the making of the engine.
The first things needed in the making of this engine are cylinders. For the making of the cylinders two fishing rod ferrules, known as female ferrules, are required. And for the heads of the cylinders, two male ferrules are required. Such ferrules can be secured at most any sporting goods store. The female ferrules should be filed down to a length of 2″, cut down on one side a distance of ³⁄₄ of the diameter, then cut in from the end as shown inFigure 7. When this has been done the two male ferrules should be cut off a distance of ¹⁄₈″ from the top as shown inFigure 7-a, to serve as heads for the cylinders.