Phone:
217.762.4917
5 Gliders
1 Tow Plane
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IGC
P.O.Box 143
Monticello, Il 61856
IGC Soaring Central Illinois
Soaring... and introduction
At first glance, gliders might appear quite foreign. Although they have the same basic shape as "regular" airplanes, something very noticible sticks out about them (aside from their long, slender wings): they have no engine. But how, then, does a glider pilot stay aloft?
Gliders are always sinking through the air around them due to the unescapable force of gravity. Yet gliders can stay up for hours without consuming one drop of fuel and without losing one foot of altitude. How?
To understand how gliders can seem to "defy gravity", it is first necessary to understand the atmosphere in which we live. This vast collection of gases is ever-changing and in constant motion; although we can't see them, vertical disturbances in the air are created by weather patterns, the terrain, and solar radiation. In some places, air is sinking rapidly toward the earth. In other places, air is moving steadily upward. This is sometimes the cause of turbulence experienced on airline flights.
In order to remain aloft, glider pilots locate and fly into areas in which the air is rising faster than the glider is descending. The result of this is a net gain in altitude. For instance, suppose a glider loses 2 feet of altitude per second in a glide through the air. If the pilot positions the plane into an air current rising at 2 feet per second, then any altitude loss will be canceled out and the result will be that the glider remains at a constant altitude. Glider pilots commonly refer to this situation as being in "zero sink".
Suppose, however, that a pilot flies into a vertical current of air which is rising at 5 feet per second. In this case, the glider will gain 3 feet of altitude per second. Flights of over 1,000 miles and many hours at speeds well over 100 mph have been performed in gliders.
This is the ultimate challenge of the glider pilot: to defy gravity and read the environment around him to find sources of lift. Our lift in central Illinois comes from thermals. Thermals are complex, but in general they are bubbles of air that are less dense than the air around them. Because they are less dense, these bubbles rise, sometimes at great speeds and to great heights (even to 10,000 ft. and higher). By circling in these rising bubbles, the glider is carried skyward at 200, 500, and even 1000 ft/min or more!
But how do pilots find thermals? This is perhaps the greatest challenge of all, and it is a challenge never fully met. A pilot can spend his lifetime soaring, and never know exactly where a thermal will be. But thankfully, Mother Nature leaves pilots with a few clues as to their existence.
Cumulus clouds
(the big puffy ones that look like cotton balls) can be a signpost, telling of a
thermal underneath it. The shape of the cloud, color, size, morphology, and
location are all additional clues as to whether there is strong lift, weak lift,
or in fact sink. Birds are often seen circling in thermals, and many times a
glider pilot will circle along with a hawk in the same thermal. Other clues,
such as corn husks or dust rising in the air, movement of crops in a field
below, and the landscape itself can give clues as to the existence of thermals.
But the biggest indication is a big kick in the pants as the altimeter winds up,
the ground falls away, and a smile comes across the pilot's face.
Soaring is one of the most rewarding sports on earth. To be able to achieve such great heights, travel such great distances, and soar for so long without an engine--relying solely on piloting skill and some help from Mother Nature... is an accomplishment unmatched by any other activity.