Radio Control: Scale
OPERATIONAL details: All Scale modelers who aspire to produce a Scale masterpiece with completely cowled engine have a common problem. It becomes a challenge to hide the necessary glow plug connector and needle valve adjustment to preserve the smooth external surface of the cowl. Some of us look for the easy way out and only make an effort to minimize the conspicuous appearance of the eyesores. We come to the conclusion that a large hole in the cowl for insertion of the glow plug connector doesn't really look too bad, after all; or, we decide to use the smallest external connector and hope it will escape notice. Our own Scale aircraft, numbering about 20, all use the same glow plug connector, an open-frame, two-conductor, subminiature phone jack.
Radio Control: Scale
SCALE MATH: Scale modelers who build from kits have some of their questions answered by the designer or manufacturer. The expected weight of the model and the suggested range of engine sizes is given on the drawing or instruction booklet. Scratch-builders ask searching questions on such important matters as a projected estimate of model weight and engine requirements, and the answer really is needed in the early stages of design. Once a model size has been decided upon, wingspan and area are a straightforward function of the scale ratio, that number which represents the difference between full-size aircraft and the model. We simply divide the prototype's span by the scale ratio to determine the model's span.
Radio Control: Scale
PARIS FAI MEETING: The annual trek to Paris for rules and technical specifications is finished, and we brought back some rather astonishing results. For many years we have heard the lament from U.S. competitors that FAI model specifications were too restrictive, particularly on engine displacements. It was generally agreed that the day of a single .60 two-stroke engine in a Scale model was long since a thing of the past, and yet the FAI rule book persisted in this upper limit. The restraining limit was imposed originally because of the suspected unreliability of earlier radio equipment and because of a general regard for safety in the days when models could be lethal missiles in the hands of novice pilots. Actually, some of these conditions may continue to exist, but it has become increasingly apparent that the old restrictions were somewhat antiquated and were stifling competition.
Radio Control: Scale
PIANO HINGE: The ubiquitous piano hinge is used on many aircraft for cowl and hatch hinge joints. It is used for good reason, as it affords a very secure hinge arrangement with light weight and adaptability. Its only real drawback is its inability to follow a curved line. If we see a piano hinge, be assured that there are no compound curves in the cowl! Description of a piano hinge: It is the continuation of interleaving hinge points with a long wire passing through all segments. It can be of any length. We have seen models with operational piano hinges, and some of these were quite well-made, considering the fact that the modeler had produced them by handwork. With small models, however, the problem is that Scale appearance is lost due to difficulty in obtaining true dimensions in diameter-and especially in the spacing between hinge segments. Our own best efforts have been in the direction of a reasonable simulation. We are always flattered when someone asks their source on the assumption that they are a commercial item for purchase.
Radio Control: Scale
NEEDLE VALVES, again: Our recent column item about needle valve extensions sparked a letter, with sketches and photos, from Sam Abdow showing his method of reaching a hidden needle without making a hole in the cowl. He begins by making a spring approximately 11/4-in. long using 1/32-in. music wire. This is roughly 40 turns of wire, closely wound on a mandrel that will produce an inside diameter of 3/16 in. One end of the spring is then soldered over a 3/16-in. brass tube which is cut to the proper length to reach the open rear edge of the cowl. He then solders a short 8-32 socket-head Allen screw into the other tube end. The music wire spring is then soldered to the needle. Adjustment of the needle can now be made using an Allen wrench.
