A radio-controlled glider is a scale model of glider , remote controlled from the ground.
A glider is an aerodyne devoid of engine . Glider practice is gliding . It is an aircraft equipped with lift planes with significant elongation conferring a very low glide angle. It is controlled by mastering the three axes of roll , pitch and yaw . Gliders can be put in the air in four different ways. The most common is towing by an aircraft called tug, throwing it by hand (for hand-launched gliders)), the third less common is the winch and finally more rarely, by its own means thanks to a motor is fixed or (most often) retractable. These are motorgliders . An action on the remote control makes it possible to turn off the engine once at altitude, or even to restart it.
The radio-controlled gliders measure up to more than 11 meters of wingspan. The use of ascents, thermal or dynamic , makes it possible to maintain a sufficient altitude.
They are made using a wide range of materials that range from balsa to composite materials, the material being chosen according to the desired use (See aircraft model construction techniques ).
Main building blocks
There are three essential parts:
- The wing:
Its function is to ensure the lift of the machine.
It consists of two wings also called feathers that provide lift. These may have at their ends, on the trailing edge (rear part of the wing), tilt flaps that control the roll axis .
Each wing can be equipped with air brakes which are devices whose function is to increase the rate of fall of the machine. The best-performing models also have curvature flaps, sometimes called high-lift devices, whose function is to increase lift at low speeds and reduce drag in high speeds.
- The fuselage:
Its function is to shelter the accessories, and its connection with the empennages and the wing ensures the control of the three axes: lace, roll, pitch.
- The empennages:
Their function is to ensure the control of the pitch and yaw axes, and for the horizontal stabilizer flight stability. Today, they consist of vertical and horizontal “T” planes that carry the rudders (rudder) and depth also called stabilizer. In model making the empennages can also be arranged in crosses and in “V”,.
Fixed Helicopter Motorblades
The gliders with fixed or variable pitch propeller are generally classified as tourist-class sailplanes (Touring Motor Gliders (TMG)). TMGs can take off and sail like an airplane and fly like a glider , engine off. They are equipped with engines at the front, similar to small planes. The large size of the gliders provides average performance in glider mode, worse than conventional gliders, but motorgliders are more efficient than conventional light aircraft.
A motorglider must be able to take off autonomously because it is not equipped with a hook to allow their takeoff via a tug or a winch as a conventional glider. The configuration of the landing gear on motorgliders is conventional . Some motorgliders have only one main wheel and auxiliary wheels for driving.
Because of the increased drag due to the stopped propeller and the configuration of the landing gear, motorgliders are rarely used in competition.
Autonomous gliders (retractable propulsion)
The retractable thruster is usually mounted on a mast that pivots up and out of the fuselage , at the rear of the cabin and the wing attachment. The fuselage has engine compartment hatches that open and close automatically, similar to landing gear hatches. The motor can be positioned on or at the bottom of the pylon. New designs have fixed the engine in the fuselage, only the propeller, mounted on a pylon or in front of the glider, is mobile to reduce noise and drag.
Unlike TMGs, most freestanding gliders are also equipped with tow hooks and winches. They have a landing gear like conventional gliders, but in addition they have small wheels at each end of the wings to allow taxiing. The two-stroke engines generally used are not suitable for reduced power operation for cruising flight. Instead we use a dolphin flight, that is to say a climb with the engine and then a maximum fineness in glider mode.
Autonomous gliders take off like conventional gliders. Once in the air they can cut the propulsion or restart it to regain altitude.
The propeller may be of a rigid 2-blade design, or may have more than two corolla-shaped blades in the fuselage after the propulsion system has been stopped.
In model making there are different categories of gliders:
- The early gliders, wingspan around two meters, they can be foam like expanded or extruded polystyrene or expanded polypropylene, or balsa. They are rarely made of composite fiber because of their relatively high cost. They are driven in two axes or three axes.
- Hand-thrown that rarely exceed 1.50m wingspan, they launch by hand to hang the bubbles, there are two categories of hand-launched.
- The intermediate gliders for confirmed pilots, which can be model or semi model, with a wingspan of 2.50 to 3.50m, they can be equipped with airbrakes or shutters of curvatures to improve their performances according to the ranges of speeds.
- Large feathers are often models of retro or modern gliders of a size that exceed 4 meters, some up to 6 or 7 meters.
- Competition gliders:
- Competition gliders for thermal flight of duration, speed, distance winched with electric winch (F3B)
- Gliders flying thermal flight of duration moored at the race (F3J)
- The fly gliders of duration durability flying launched by hand (F3K)
- Gliders flying slope flight ( F3F )
- Competition gliders with towed glider, duration and speed tests (F3I)
- Gliders of model competitions
- Electric glider motorcycles (F5B): A category apart, between gliders and airplanes: electric powered gliders, whose altitude setting is performed with an electric motor, the flight continues in hover. 2 events: speed between two bases spaced 150m and duration with landing on target, all in the same flight.