Speed to Fly and Thermals

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Travel Speed for downwind XC

South Africa Thermals Highest temperature can be expected between 15.00 and 17.00 in a day. Means thermals are highest late in the afternoon  Thermals start off in the day narrow and strong and become wide and weak in the late afternoon

Chance of finding a Thermal Thermal probability 1.5 km 8 km 15 km 0.5 m/s 20% 90% 99% 1.0 m/s 10% 60% 84% 2.0 m/s 5% 30% 52% 3.0  m/s 2% 18% Thermal probability 1.5 km 8 km 15 km 0.5 m/s 20% 90% 99% 1.0 m/s 10% 60% 84% 2.0 m/s 5% 30% 52% 3.0  m/s 2% 18%

Distance to next Thermal Rule of thumb is that one needs 2.5 times the height of a thermal to find another one. For Dunnottar, low cloudbase days work best. 700 meters and a glide ratio of 6-7 = 4-5 km 700 meters x 2.5 = 1.8 km to the next thermal 1500 meters x 2.5 = 3.8 km, just possible 3000 meters x 2.5 = 7.5 km, fly Welkom

Where to find the lift under a cloud  On a weak wind day on the sunny side Or up wind and towards the sun. For Gauteng area, wind is predominant NW. Sun in the afternoon is shining from the NW, so look for the lift in the NW corner of a cloud

That’s all for today Mort recommends that you got your recovery organized More at http://marca.homelinux.com/ulf/skygod/s2f/s2f.html