You might want to think of a thermal as a rising, spiraling mass of warm air... Thermals are bubbles of air that are heated by refraction, heat radiating off the ground. A thermal starts as a mass of cold air which then gets heated and breaks off, forming a bubble of warm rising air, because hot air tends to rise. You can take advantage of the rising air to stay aloft with a glider. So, to catch a thermal, you need to be able to "see" the invisible masses of hot air. You will learn to do this by observing what kind of land radiates more heat, for example a parking lot or highway will radiate far more heat than a lake or dense woods. To catch thermals you need a stable glider with a very efficient airfoil...
You launch the glider, usually by means of a motor or high start. A high start is a long piece of Bungee cord that acts as a slingshot with your glider as the load.
You circle around and if there are any thermals at all, you will see that sometimes one wing tip will rise and cause the plane to bank. What you have to do is turn hard towards the area where your wing tip rose: if the left wing tip rises you bank hard left. By circling around, you will soon find a spot where the plane rises more and more as you spiral. You should keep spiraling in that spot, smoothly, and the warm air will carry your plane upwards. You can then disengage the thermal and look for another one.
The best kind of glider to start with will be a glider with a large wing. the bigger the wing is, the better. The wing should have some Dihedral, which means it curves upwards at the tips. It will usually be a 2 or three channel plane, which means that you have only elevator and rudder control, or elevator, rudder and flaps/brakes. The rudder is like the rudder in a boat: it steers the plane. The elevator controls the elevation and descent, and the flaps are surfaces at the back of the wing that extend or lower themselves to provide more wing area and wing efficiently. Brakes are surfaces that partially destroy the wing's efficiency, lowering speed for easy landings.
You should buy a four to six channel radio to begin with. Your radio will come with servomotors, small devices that move the surfaces, a battery and a receiver, as well as some accesories. Futaba and Spektrum are very reliable brands of Radios, so you should want to go for the best you can afford.
Here I will give you a few links to good starter planes and radios:
http://www3.towerhobbies.com/cgi-bin...=LXEFJ4**&P=ML : The T4YF, the best starter radio. $119.99
http://www3.towerhobbies.com/cgi-bin...&I=LXSFY3&P=ML : The 6EX, a more advanced and flexible radio which uses 2.4 gigahertz technology to eliminate interference, available for $ 259.99
http://www3.towerhobbies.com/cgi-bin...?&I=LXJ597&P=0 : The spectra, a great glider with a motor for easy thermal catching, kit form
http://www3.towerhobbies.com/cgi-bin...?&I=LXFG09&P=0 : SIG riser, easiest plane to fly, very cheap, available in kit form
http://www3.towerhobbies.com/cgi-bin...?&I=LXELP0&P=0 : The Gentle Lady, I laerned to fly with one of these, available in ARF (Almost Ready To Fly)
http://www3.towerhobbies.com/cgi-bin...?&I=LXJYP9&P=0 : The Spirit 100, Great plane, available as an ARF
http://www3.towerhobbies.com/cgi-bin...?&I=LXLGM6&P=0 : The Fling 2M, very light and very efficient airfoil, great for thermals, available as an ARF and also available in a 50 inch version.
http://www3.towerhobbies.com/cgi-bin...1p?&I=LZ1491** : Finally, the Spectra electric assisted glider, available as an Ultimate Combo for 225 dollars. Includes everything you need, even rubber bands and alkaline batteries for the radio...
Well I hope that helps. Now I need to rest my poor fingers, Ive been typing too long...
