Electric RC AirplanesWritten by Andre McFayden
In recent past, almost all rc airplanes were powered by small internal combustion engines, using liquid fuels. Models powered by electric motors were few and far between. The electric rc airplane is now becoming much more common, especially in models designed for beginning pilots. Electric power advantages include reliability, convenience, low noise, low vibration, and lack of fuel residue (clean). The disadvantage of early systems was low power. However recent electric airplane motors, combined with advanced batteries, have increased performance of electric rc airplanes dramatically. In more common Brushed motors, current switching is done using sliding contacts known as brushes. The contacts get hot and wear out over time. In Brushless motors, switching happens electronically using a special voltage regulator (speed controller). This second type of motor and its controller are more expensive to make. Its advantages are no maintenance and higher performance. There are three main types of batteries in use for electric airplane motors. These are Nickel Cadmium (NiCad), Nickel Metal Hydride (NiMH) and Lithium Polymer (LiPo). LiPo batteries are lighter for a given application, but tend to be more expensive than NiCad or NiMH.
| | What is Scrimshaw?Written by by: Elly Kendall
American scrimshaw dates back to at least 100-200 AD in North America, practiced for centuries by native groups along Northwest Coast. Not wanting to simply discard teeth and bones of animals hunted for food, native cultures invented a new style of art that would later be known as Scrimshaw, one of only a few indigenous American crafts. While other cultures around world, such as Orient artists, certainly worked in ivory and bone, style of North American cultures and that of Yankee sailors who followed were uniquely their own, making scrimshaw a traditionally American art form. It was adopted by Yankee whale men of early 1800's. Two- to five-year voyages quickly became monotonous, so whale men turned to working with baleen, whale teeth, and jawbones, all of which were in abundant supply. In fact, on many ships, whale teeth were part of pay and were often traded in port for goods or services. The origin of word is obscure; one interesting etymology is a Dutch phrase meaning "to waste one's time!" The term "scrimshaw" also applies to carved or pierced bone or ivory, since much of whale men’s work was carved rather than etched. Scrimshaw art is a slow and tedious process where one mistake can ruin an entire piece. Creating ivory sculpture or carving is equally unforgiving work. Scrimshaw is not an art form for impatient. Each piece can take from 30 to over 900 hours to complete. Scrimshaw is usually defined as carving or embellishment of ivory or bone. Today's definition would more likely be thought of as intricate incising of ivory to produce images of unbelievable detail. Incising and engraving could both describe scrimshaw method. Extremely sharp scribes scratch surface of ivory, and then paint or ink is rubbed into incisions. Stippling is a technique of employing thousands of tiny holes that are then carefully filled with pigment to reveal a beautiful work of art and to create fine shading.
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