Winding a loose dry rubber motor is not desirable for a few reasons. First, the rubber is usually packed in talc. The small crystals will cut the rubber as it is wound, causing it to fail. Usually exploding in the fuselage of a new model. Washing the motor with soap and water will remove this talc. Friction will also prevent winding a dry motor to maximum turns as it abraids itself, again causing a premature failure. Finally, energy is also lost overcoming friction as the motor unwinds. This reduces the amount of torque the prop sees resulting in shorter flights with less power.
Lubricating the motor allows a much larger number of turns to be applied before failure. The motor will also unwind more easily, as the strands can easily slide against each other. Both of these factors will increase duration, and altitude of a flying model.
Like most magic formulae, the secret recipes of successful rubber lubes have been closely guarded by their creators. For years the traditional recipe has been a mixture of Glycerine and Tincture of Green Soap, both available from a pharmacist. Of course the magic ratios, and any other secret ingredients, were not often divuldged at contests! Today, this mix is still used, as it has the advantage of being easily washed off the motor if retying is necessary. Other easily available lubes being used are ArmorAll vinyl protectant and SylGlide bearing grease. Both are available at auto parts stores.
A common way to lube a motor, is to put some of the lube in a plastic sandwich bag. The bag helps keep the lube off your hands. Smear it around a bit, then add the motor. Rub this all around in your hands and then remove and install the motor. You're ready to go! Needless to say, a bit of experimentation will quickly reveal the benefits of winding a well lubed motor.
|Stretching the motor while winding will also increase the number of turns it will safely accept. Most modelers will stretch a motor to 4 or more times its relaxed length while winding. After about half of the total turns are wound, the modeler slowly walks towards the model while finishing winding. How is the model held? Either line up a friend to hold it for you, or use a mechanical device called a stooge that holds the model by the rear motor peg. Some folks have luck stretch winding alone, as shown.
Winders | Jason's Quadruplanes
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