content_image/540973.jpg content_image/540974.jpg
a climb. There are several techniques and variations to centering. One method involves paying close attention to where the thermal is strongest; for instance, toward the northeast or toward some feature on the ground. To help judge this, note what is under the high wing when in the best lift. On the next turn, adjust the circle by either straightening or shallowing the turn toward the stronger lift. Anticipate things and begin rolling out about 30° before actually heading toward the strongest part. This allows rolling back toward the strongest part of the thermal rather than flying through the strongest lift and again turning away from the thermal center. Gusts within the thermal can cause airspeed indicator variations; therefore, avoid “chasing the airspeed indicator.” Paying attention to the nose attitude helps pilots keep their focus outside the cockpit. How long a glider remains shallow or straight depends on the size of the thermal.  [Figure 10-10] Other variations include the following: [Figure 10-11] 

1. Shallow the turn slightly (consider 5° or 10°) when encountering the weaker lift, then as stronger lift is encountered again (feel the positive G, variometer swings up, audio variometer starts to beep) resume the original bank angle. If shallowing the turn too much, it is possible to fly completely away from the lift. 

2. Straighten or shallow the turn for a few seconds 60° after encountering the weakest lifts or worst sink indicated by the variometer. This allows for the lag in the variometer since the actual worst sink occurred a couple of seconds earlier than indicated. Resume the original bank angle. 

<img src='content_image/540973.jpg'>

3. Straighten or shallow the turn for a few seconds when the stronger seat-of-the-pants surge is felt. Then, resume the original bank. Verify with the variometer trend (needle or audio). 

<img src='content_image/540974.jpg'>

