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Gliding is many different things to many different people. For some, it is a casual hobby and a way to meet new people. To others, it is an inexpensive way to get airborne, and, for others, it is the cutting-edge of sport for racing or aerobatics. For everyone, it is a silent, graceful way of flying without an engine, which poses questions such as how do you get airborne and how do you stay up?

Gliding started in a serious way in this country in the late 1920s and the British Gliding Association – who administer the sport in the UK – was formed in 1929. The early sites/clubs were nearly all based near or on hills where the pilots could use ridge lift to stay airborne. Today other forms of lift – thermals, waves, convergance fronts, sea breeze fronts – have been discovered, and the association now has about 100 member clubs throughout the UK. There are over 10,000 active glider pilots who between them, make approximately half a million flights a year.

Today’s gliders soar using the same air currents that birds use to fly, but have also been designed with the aerodynamic efficiency that enables top speeds of up to 170 mph. Distances of over 600 miles have been covered in one day in the UK and heights of almost 40,000 feet have been achieved.

These gliders have been developed from the early gliders by a process of evolution. Almost without exception all those built today are based on composite plastic materials with highly efficient wings, maximising lift and minimising drag. However, there are over 1,000 members of the Vintage Glider Club, founded in 1973 at Husbands Bosworth, which has branched out internationally in 30 different countries. They have some 780 classic wood and fabric gliders, and hold national and international rallies every year to show off the classic gliders of the 1930s to 1960s.

In order to launch you need a little assistance. There are several ways of achieving this. The aerotow launch is very docile and involves being pulled by a light aircraft with a strong rope in between. When the combination gets to the required height the glider releases the rope and is free. Winch launching is probably the most common and involves being attached to a winch by a long reel of steel wire. The wire is pulled in by the winch and the glider gets the speed to fly into the air like a kite. Once the glider is almost overhead the winch, it releases the wire and is free to fly under its own power.

Now the glider is in the air and it needs to stay up. A glider is always coming down through the air it is flying through, so to stay up gliders need to find air that is going up at least as fast as the glider is descending. On a summer’s day you can often see birds circling without flapping their wings – they are thermalling. A thermal is a volume of air that has been heated by the sun more than the surrounding air. If you were standing on sunlit concrete you would feel warm. As you know, hot air rises, and it is circling in this warm air that allows the birds and the gliders to rise. We don’t always have to read the ground to find a thermal because the tops of the thermals are often marked by a cumulus (cotton wool type) cloud. Thermals are used in cross-country flying – you climb in a thermal to gain height and then move forward to the next thermal on the track and repeat the process. Distances of over 1,000 km have been covered like this.

Another way of staying up requires a hill (ridge) and the wind to blow against the face of it. When the wind hits the hill it is forced upwards. Again, it is this upward movement of air that allows gliders to stay airborne. With a long ridge it is possible to cover large distances without turning, generally flying fast and low to stay in the best lift close to the ridge.

Similar to ridge lift is a phenomenon called ‘wave lift’. Again, it arises from the wind blowing against a hill, but this time the air comes back down on the far side of the hill and bounces off the ground and goes back up, creating a very smooth upwards flow of air. Often this is capped by a cigar shaped ‘lenticular’ cloud. The wave may go back down and up for several cycles, meaning that you don’t have to be near the hill to use it. The furthest distance flown by a glider using this type of lift, in one flight in one day, is just in excess of 3,000 km in the Andes.

One further type of lift is caused by a sea breeze front. These usually occur on warm days in the late afternoon. The relatively cold dense air comes inland from the coast over distances up to 30 or 40 miles. The less dense warm air over the land rises over the cold air, once again creating lift which the glider can soar along, almost as if it was flying beside a hill. In the north east of England these fronts can often be 50 miles long and rescue pilots on cross-country flights when the regular thermals are weakening towards the end of a day.

Gliding is a sport for all ages – from those who go solo on their 16th birthday, through club cadet schemes, to those who take it up on early retirement and continue into their eighties and nineties. There is no upper age limit! It is a truly diverse sport that can be enjoyed at all levels: from the thriving club scene, to aerobatics, to the international racing competitions currently dominated by British pilots (with five World Champions).

Most of the gliding clubs will arrange ‘taster days’ or trial lessons for individuals or groups. It is a good team building exercise. If you take up gliding you don’t have to become a racing or aerobatic pilot. Many people just enjoy seeing the world from a different viewpoint, or even enjoy the thrill of trying to perfect their basic flying skills. A large number of glider pilots also carry on to become instructors, so that they can pass on the skills they have learned.

(This article was originally published in Director of Finance 2004 edition)