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Section 8: Basics of Thermal Flying
The following is intended for those pilots who have mastered flying the Thermalaire EP. Thermal flying is by far the most
difficult aspect of glider flying; however, it can be the most rewarding. For more information on thermals, check your
local library or the Internet. There are many books and articles available that detail what thermals are and how they work.
Basically speaking, thermal lift is created by areas of warm air rising from the ground. As the ground heats up from the
warmth of the sun, the air above it will begin to warm. This is especially true over terrain such as a freshly plowed field
or a paved parking area. As the air heats, it will begin to rise and allow cooler air to move in to replace it. This air, in turn,
will heat up, rise, and you will get a continuous current of rising air.
Thermal flying is truly an art but there is also a good amount of luck involved in finding the perfect thermal. There are
ways to hone your skills so that you can become an artist in flying thermals rather than remain a hopeful novice who
blunders into them by accident. The following are some keys to begin the process of becoming a better thermal pilot.
The first key is to become very familiar with the way the Thermalaire flies. Knowing the way it responds when entering
and exiting thermal lift is essential. There are things you will notice as you fly the Thermalaire more and more. You need
to be familiar with the airplane so that you can recognize when it is flying normally and when it is responding to up or
down air. It is very hard for the novice to tell what is happening to a new airplane in regards to the air. He or she is
uncertain if the movement is due to something that the pilot did or due to air movement. You want the airplane to be
properly trimmed out so that it flies smooth and stable and so you know how it responds when you turn. Polyhedral
wing
designs, like those on the Thermalaire, try to remain stable and are easier for the novice to fly than straight wing planes
(i.e., wings with no dihedral) and, more importantly, are responsive to hitting the side of a thermal more dramatically than
straight wing planes do.
You will seldom hit a thermal straight on in flight. More often you will hit the side of the thermal and it will lift one wing
more and literally throw your airplane away from the lift. When your airplane should otherwise be flying level, watch for
a sudden lift of a wing tip and turn the airplane into that area. There is a good chance that you hit the side of a thermal and
it pushed you away—into the air next to the thermal. Having located a thermal, turn into it and start circling to locate the
area of strongest lift. Tighten up the circle to get the maximum rate of climb.
Think of the air as water. No wind is a calm lake. A breeze is a slow moving stream and a heavy wind is a raging river.
Often, a pilot hits some lift, starts circling, then goes up and up and stays right in the same spot circling. Then he starts
coming down and doesn’t understand why. On a calm day, once you hit lift you can circle right there as it isn’t going
anywhere but up. It may die after a short time, but that happens. With wind, picture your lift as an escalator going
downwind at the same rate as the wind is blowing. You hit it and start to circle and you go up, but you must have your
circling go downwind at the same speed as the wind to stay on the escalator. The lift is moving and if you don’t go with
it you lose it.
Watch the tail of the airplane bounce up to see if you are hitting lift. When you fly into a thermal it kicks the tail up and
thus points the nose down. Despite this "dive" position your airplane may actually be going up in the lift. It depends on
the strength of the thermal. That "up tail" is a sign to watch for in thermal spotting.
Use your visual keys and work on your skills so you can become accustomed to thermal flying. Don't forget to watch the
birds, too. If you see birds with their wings stretched out, circling high above, you can be sure they are in a thermal.
Launch your airplane and head in that direction. They won't mind you joining them in the fun!