Gliding is the ultimate medium to experience flight; with nothing to disturb your ears but the whistling of air as you soar through it, you not only get a breathtaking birds-eye-view of the world, but a truly bird-like experience of powerless flight.
Far from a one-off thrill, gliding is a diverse sport which can be enjoyed all-year-round by all ages. Flights may be for instruction or for fun, staying close to home or soaring over 1000km across the country, a peaceful journey or packed with thrilling aerobatics.
How Gliders Fly
A glider flies in exactly the same way as a powered aircraft, in that air flowing over the wings produces sufficient lift to counteract the force of gravity. With a powered aircraft, this airflow is produced by one or more engines pulling it through the air horizontally. Gliders however do not generally have engines and so achieve this horizontal motion by using gravity to turn height (potential energy) into motion (kinetic energy) by constantly flying at a very slight pitch towards the ground.
Whilst this means a glider is always falling in relation to the air around it, part of the skill in becoming a pilot involves learning to find and use areas of the sky where air is rising, which in turn raise the aircraft leading to longer flights – regularly many hours! This is known as soaring, and is discussed in more detail in the section below.
So if gliders need height to fly, how do they get off the ground to start with? There are a number of solutions to this problem, the most popular being aero-towing (where a powered aircraft tows a glider behind it) and winch-launching (where a powerful engine on the ground pulls a glider into the air on the end of a very long cable).
Each have their own advantages, but both provide a glider with sufficient height to fly unaided for anywhere between many minutes on a cold winters day, to many hours during the summer months.
How Gliders Soar
In order to stay aloft for more than a few minutes, glider pilots must find areas of rising air in which to fly in and gain height. There's three main types of lift: thermal, ridge and wave.
Thermal lift is produced by the sun heating up parts of the ground. Warm patches on the ground then in turn heat up the air above them. As warm air is less dense than cold air, it rises, thus generating a column of rising air. These columns tend to be quite small, so gliders must turn in tight circles in order to gain the maximum lift. As most thermals will produce a cloud at the top of them, this can be a good way for glider pilots to identify where they may be.
Ridge lift is generated as wind blows against a steep hill or cliff face - the air has no place to go but upwards! Gliders taking advantage of this type of lift will fly very close to the ridge in order to catch the strongest updraft.
Wave lift occurs at quite high altitudes, and is produced by oscillations in the air caused by hills and mountain ranges. It tends to span very large areas and is usually quite strong, yet very smooth.