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R/C Basics: Sailplanes | Great Starter Planes | Tools | Field Equipment | Sailplane Terms | Shopping List

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Sailplanes Terms Ailerons— The hinged control surface on the back (trailing edge) of the wing furthest away from the fuselage. Servo power applied to the aileron makes the sailplane turn. Airfoil — The shape of the wing, as seen from the end. Flat-bottom — A wing airfoil that features a flat underside for greater flying stability. Typical in trainer aircraft. Selig 3010 — Airfoil designed to improve flying stability, often incorporated into trainer sailplane designs. Selig S-7037 — Airfoil engineered for high efficiency. Selig SA7035 — Airfoil designed for speed and easy wind penetration. Selig SA7036 — Airfoil designed for stability and lift. ARF (Almost-Ready-To-Fly) — A model which is largely prebuilt and is usually covered at the factory. May also include an engine or motor. Ballast — Extra weight added to a sailplane to help it penetrate better in windy weather or to increase its speed. Control Surface — A movable surface on a sailplane designed to change the direction of flight. May be used alone, or in combination. See aileron, flaps, rudder, elevator. Dihedral — The upward angle of the wings, as seen from the nose. Dihedral enhances stability. Trainers tend to have high dihedral, but aerobats have little or none. Elevator — A hinged control surface connected to the back (trailing) edge of the horizontal stabilizer. Moving the elevator makes the plane climb or dive. Flap — The control surface on a wing closest to the fuselage. Moves up or down, to increase lift or drag. Fuselage — The long, narrow body of a sailplane. Glide Ratio — The distance traveled in a horizontal direction compared with the vertical distance dropped on a normal glide. A 10 to 1 glide ratio means that the sailplane would lose one foot of altitude for every ten feet of distance traveled. Horizontal Stabilizer — The portion of the tail that includes the elevators, which control the plane's up and down movement. Kit — A model that requires the hobbyist to do most or all of the building work. Wooden and/or plastic parts on most modern kits are shaped or cut to large degree to minimize work. Leading Edge — The front of the wing. On-Board Gear — A term which can have several meanings. In its broadest sense, on-board gear can mean everything in the airplane. More generally, however, on-board gear refers to a more specific group of items, usually including the receiver, receiver NiCd, servos and (in electric models) the motor, motor NiCd, on-off switch or speed control. Propeller — The whirling device on an engine- or motor-powered sailplane which turns engine/motor power into thrust. May be carved from wood, or molded from reinforced plastic or nylon. Pushrods — The rods that connect servos to movable parts of the sailplane. Radio Transmitter — The part of a radio system that a pilot operates to transmit control signals to a receiver. Receiver Battery — The radio receiver's power source. Receiver— The radio component that receives the transmitter signal and relays its command to the servos. RTC — Ready-To-Cover. Describes a plane in which most major sections have been built, preparatory to covering or painting. Surfaces may or may not be factory sanded. RTF — Ready-To-Fly. A somewhat loose term used to describe a plane which requires very little or no work to prepare for flight. Usually features a significant degree of factory assembly and factory-applied covering. RTFs may also include a transmitter, engine (or motor) and other, smaller items. Rudder — The hinged part of the vertical stabilizer that moves the sailplane's tail to the right and left. Servos — The radio components that do the physical work in an airplane, by moving rods that are connected to various parts of the plane. Spoilers — Control surfaces used to quickly slow a model down for extended flight times and precise landings. Tail — The part of the airplane located on the rear of the fuselage. Includes both the Vertical Stabilizer and Horizontal Stabilizer . Tail configurations of sailplanes include: Conventional Tail: Characterized by a standard rudder and a stabilizer mounted on the fuselage. Found on the majority of R/C sailplane kits, it's easy to build and works well. T-Tail: The stabilizer is mounted at the top of the rudder, where it is less affected by the wake created when air flows over the model's wing. This design can be difficult to build. Mid-Tail: A compromise between the conventional and T-tail, the mid-tail has many of the T-tail's benefits and is also easier to build. V-Tail: The stabilizer is bent into an upward V shape, and there is no rudder. A radio with mixing capabilities is usually required. Tow Hook — A small metal hook mounted on the bottom of the sailplane's fuselage to which a hi-start is connected for launching. Trailing Edge — The rear edge of the wing. Vertical Stabilizer — The portion of the tail that provides side-to-side stability. The hinged portion of the vertical stabilizer is called the rudder. Wing— The large, horizontal surface that creates lift (the force that carries a plane into the sky) as it moves through the air. Wing Area — The surface area of the wings, as measured in square inches or square decameters. General rule: the more wing area, the more lift produced. Wing Chord — The depth of the wing, from the front (leading) edge to the back (trailing) edge. Wing Design Polyhedral — A wing with polyhedral has more than two wing panels and the angle of the wing changes at each joint. Triple Taper— The wing has three different leading edges and produces a nice compromise between an efficient crescent shape and an easy-to-build, single-tapered wing. Wing Loading — The weight of the sailplane, divided by the wing area, expressed in ounces per square foot. Planes with high wing loading numbers must fly faster to stay in the air. These are generally "performance" airplanes. Conversely, planes with lower numbers do not need as much air flowing around the wing to keep it flying. Gliders and trainer airplanes fall into this category because slow, efficient flight is desirable. Wing Root — The place where the wing joins the fuselage. Wingspan — The length of the wing, as measured from one wing tip to the other. Wing Tip — The end of the wing furthest from the fuselage. Can't find it here? Check out the R/C Dictionary! top of page

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