Many people prefer the quiet and cleanliness of gliders to power, and there is a huge range of models suitable for use as trainers. By their very nature most gliders are stable and slow flying and a model suitable for learning can be used for many years afterwards for general flying.
Most of the FAQ material, radio and model choice for example, applies equally to powered and unpowered models, but of course the absence of a power plant means there are some fundamental differences. Glider trainers will usually have rudder and elevator control, although flat field models may also include air brakes or spoilers, and more advanced models may have a range of lift altering devices.
The same criteria of lightness and stability apply to gliders, flat field types particularly will want to be lightly loaded, although models destined for flying from the slopes may be built with a slightly higher wing loading to cope with the higher wind speeds usually encountered. They are also usually smaller than thermal models and built more ruggedly, as few slopes have a flat landing area so the models need to be capable of withstanding arrivals onto rough ground.
Gliders can be split into 2 main categories, Flat Field and Slope soarers. The two are not mutually exclusive, any type of glider can be used on either slope or flat, but of course with varying degrees of success. Within these two categories are a huge range of specialist subdivisions: just as for power there are sport, scale, aerobatic, pylon racing and duration types.
Flat field models can be flown from the same type of site as powered models, and in many clubs the two types are operated side by side. Flat field models rely on thermals to stay airborne. Thermals are columns of rising air generated by heat in the ground . On a good sunny day a thermal may rise many thousands of feet into the air, and full-size glider pilots take full advantage of them to climb to tremendous altitudes, allowing flights of hundreds of miles to be undertaken. R/C gliders use thermals in the same way, although they are limited in altitude by the eyesight of the pilot.
Thermal gliders are launched either by an aero-tow or some sort of ground based line.
This is the same method as used by full-size gliders. A powered model, the tug, is fitted with a length of line which is attached to the nose area of the glider. The tug pilot then takes-off, towing the glider up to the required altitude. The line is attached at both tug and glider end with a radio controlled release so that the glider pilot can cast off when ready and then search for thermals. The tug pilot also has a release so that the glider can be dropped in case of problems.
These use either a bungee, winch or hand-tow.
is a length of some elastic material, extended by a longer length of non-elastic line. The end of the elastic length is fastened to a stake in the ground, and the other end has a ring which is slipped over a hook on the bottom of the glider fuselage. The glider is then pulled backwards, stretching the bungee, and when a suitable tension is achieved the glider is released and the contraction of the bungee pulls the model into the air.
is an electrically powered spool wound with line. One end is attached to a hook under the model fuselage, the other is fed around a pulley and onto the spool. When the motor is activated the line is wound rapidly onto the spool, winchingthe glider into the air. The motor is usually activated by the pilot with a foot switch, and the motor is pulsed on and off to adjust the line tension and hence the model speed.
A Hand tow
is the simplest: a length of line attached to the glider at one end, and held at the other by someone capable of running fast! This tows the glider into the air. Sometimes the line is wrapped around a pulley to get a mechanical advantage; sometimes more than one person is used to pull the towline.
Slope Soarers are designed to be flown off hills, where the lift needed to keep the model aloft is generated by the wind blowing up the slope of the hill. They are usually launched by standing at the top of the slope, facing into the wind, and throwing the model forward into the lift. The model is then tacked backwards and forwards across the slope, gaining height from the lift generated by the flow of wind. On a good slope this lift can extend many hundreds of feet into the air, and models may be climbed until almost out of sight.
Slope flyers are not restricted to slope generated lift: on hot days there may be thermals which can be used in the same way as by the flat field flyers, and in some locations, where there are other hills upwind, there may be wave lift to make use of.
Once you are airborne, you can keep flying as long as the lift, and your radio battery, lasts. This makes slope soaring an excellent way to build up flying hours, there being no need to keep landing to refuel or recharge. The basic flying skills, and the manoeuvres needed to fly and land safely are similar enough to power flying that they are easily transferred. The drawbacks are the lack of landing practice - you can't do touch-and-goes with a slope soarer - and the reliance on the wind for lift. If the wind drops, you have to stop flying. However, for many people the lack of an engine, and its attendant noise and oily residues, make slope soaring the most attractive type of modelling.