At all times attempt to assess whether the model is going up or not. If it has been going up and suddenly stops doing so, it has drifted away from the centre of the lift< and immediate steps are required to centre it again.
Rather than go into a great deal of further detailed, and perhaps difficult to follow description of possible situations, the following listing is an attempt to summarise some “golden rules” for thermal detection and flying.
Take note of changes in wind direction and strength.
Watch any birds or other models closely.
Watch the behaviour of your model on the line.
Once free of the line, if not in obvious lift, trim the model to best glide angle (i.e. slightly faster than the minimum sink trim), move over to one of the “favoured” areas and trim the model back to minimum sink for the search.
When looking for lift always fly up-wind or crosswind at some distance so that the rate of ascent/descent of the model can be accurately assessed. This is impossible if the model is directly overhead, and it should only be flown in this position if in obvious lift.
Watch the model carefully and, if anything upsets the normal flight path, be prepared to react to it.
If the model stalls suddenly, iron out the stall and fly up-wind for a few seconds, then try one smooth circle. The question to ask it “Did it come down?” during the circle. If the answer is “no”, circle again until satisfied that you have found lift, or not, as the case may be.
If the model, suddenly turns one way, turn back into the rising wing, fly straight for five or ten seconds, and then circle. When flying into the edge of a thermal, the model will tend to be pushed away, so one always turns into the rising wing in these circumstances. If the “push” is violent, as it sometimes can be, it may be easier and quicker to turn with it, completing the three-quarter circle, and the straightening up, rather than fighting the model back the other way.
If the model speeds up, and starts to sink faster than normal -- move — and quickly. If the sink is strong you will have a very short period of time to get out of it before too much height is lost. Never move directly down-wind away from sink — it will catch you up again. Fly away at 45 degrees to the wind direction, either up-or down-wind. Concentrate on keeping the model moving smoothly.
Once established in lift and circling, constantly assess the rate of ascent of the model. If the rate of ascent decreases, the model is probably drifting away from the centre of the thermal. Move it around by varying the circle to try and re-establish the rate of climb.
When following a thermal down-wind, always remember that you have to get back, and, almost certainly, when you leave the thermal to fly upwind, you will encounter an area of sink. Allow extra height to cope with this.
Do not get carried away and go too far downwind or too high — many models are lost in this way. Build up your ability and confidence by stages until you reach the maximum height and distance at which you can comfortably fly the model.
When leaving a thermal to land within slot time in a contest be careful not to overstress the airframe. Start the descent in good time, use airbrakes if these are available, and, rather than diving violently, concentrate upon flying round in wide circles in a constant shallow dive.
Using the lift is a question of perfect model trim and lots of practice. Many people who do not fly thermal soarers dismiss it as a game of “luck”. Certainly, in a season’s flying, even the most inept pilot will find one or two thermals, and this is the “luck” element. However, as a famous golfer once said, when accused of being lucky “It’s funny, the more I practice, the luckier I get!” This is certainly true of thermal soaring; it is only when the stage is reached where actually flying the model is purely automatic, and all the pilot’s faculties can be concentrated on assessing the conditions and reacting to visual feed-back from the model, that the potential of model and pilot will be truly realised.
All this practice may sound like hard work — and would be if the flying were not so enjoyable itself. However, when you can screw your model up the invisible rising air column until it is a eye-straining dot, and yet return to a spot landing within feet with perfect confidence, after a flight of ten, twenty, thirty or more minutes, from a launch which could only give four or five minutes without assistance, all the practice, all the trimming will have been well worthwhile. Return to Page 1.
