LUUGS :: About

Gliders

Gliders have long thin wings for efficiency, with spans from 15 to 30 metres. Some have a glide angle of nearly 60:1, meaning that from a height of 1 mile (a typical cloud base in summer) they will glide 60 miles before they have to find more lift. Made from wood and fabric, metal or fiberglass, gliders are very strong. Most can perform loops, and some can fly upside down.

The basic controls are the stick, for ailerons and elevator, and rudder pedals. The ailerons roll the glider to turn, the elevator pitches the nose up and down, and the rudder yaws the glider from side to side. Airbrakes are used to reduce the glide angle for landing.

There are a few instruments, such as an airspeed indicator and altimeter. The variometer shows how quickly the glider is going up or down, and is used to find the best lift. Most gliders have more than one, with an audio option so that the pilot can keep attention focused on what is happening outside the cockpit.

Gliders usually fly at between 35 and 150 knots; generally they are flown at their best glide speed, around 40-50knots.

(The image on the right can be enlarged by clicking on it)

Learning

Gliding is not difficult; if you can drive a car you can fly a glider. (If
you can't drive a car, don't worry: as the minimum age for gliding is 16,
pilots often go solo before they can drive). Gliders are fairly stable and
will fly along quite happily without any input from the pilot. Reaching solo standard takes on average 40-60 flights.

Just as you can learn to drive without ever looking under the bonnet, so you can learn to glide without needing to know much about how an aeroplane flies. However, a bit of aerodynamics is useful and interesting. Have a look at:

http://www.grc.nasa.gov/WWW/K-12/airplane/short.html

Launching

Gliders can be towed behind a light aeroplane, up to almost any height, and can be dropped in an area of good lift to begin a flight. The cheaper option is to launch with a winch, more or less like a kite, up to about 1800ft. Winch launches are exciting (0 to 60 in a couple of seconds) and are used for most training flights.

On all types of launch someone has to hold a wingtip to keep the wings level until the glider is traveling fast enough for the controls to be effective (there is only one wheel). As gliders also have to be towed out from the hangar and pushed back to the launch point after landing, and as instructors are mostly ordinary club members like everyone else, this makes gliding much more of a team sport than it might appear.

Lift

Thermals: In summer the main source of rising air is convection caused by the sun warming some areas (such as sun facing slopes, dry fields, concrete) more than others. Bubbles of air that are warmer and lighter than their surroundings rise, forming the fluffy white cumulus clouds that you see on a nice day. Gliders circle to climb up to cloud base and set off to the next thermal, or carry on up into the cloud.

Hill lift: Wind blowing against a slope is deflected upwards and produces good lift to about twice the height of the hill, so that gliders can fly along the slope. For this reason many gliding sites are on the top of a ridge.

Wave: In the right weather conditions standing waves are set up downwind of ranges of hills such as the Pennines. These waves can be used to climb to heights of a few miles.

Gliding Weather

Gliders will fly in rain, but won't be launched in it, as water on the wings affects the performance, and because the visibility is seriously reduced. Likewise low cloud will stop flying. Any other weather is fine, unless the wind is very strong. More specific conditions are needed for good thermals and wave, and pilots devote a lot of time to trying to spot the good days.

Online forecasts and links:

http://www.itadvice.co.uk/weatherjack/STARS.htm

See also the links page for more useful sites