SAFA Skysailor Magazine

34 SKY SAILOR November | December 2022 At 10,000ft, noted distance and direction from the start point assisted in calculating overall wind speed and direction. This informa- tion, alongside the wind shear/s encountered, set the tone for the day’s task. I commonly encountered up to four different air masses in the column, along with other anomalies. Once I encountered a jet stream at 4000ft that cut off thermals that otherwise went to 10,000ft. On such days, it took patience to stay with the thermal in almost zero lift until you ‘popped’ through, then take the thermal to 10,000ft. This information was delivered to competition pilots at the morning briefing and some pilots used it successfully to complete the task. Upon landing, the data I recorded was transferred to a ‘Mol/Cu’ chart for analysis. The chart was created by Paul Mollison and 'tweaked' by Denis Cummings. It was invalu- able for calculating various air masses and how long it would take to heat sufficiently to create thermals. The chart was so accurate that I could calculate the strength, longevity and height of each day's thermals. On one particular day, it Flatlands 1987, 90 pilots on the start line at 12:30pm awaiting the first inversion break Opposite page: Teaching pilots the ‘new’ towing system John’s Red Truck All photos: John Clark Flatlands memories by John ‘Red Truck’ Clark For the first few years of the Flatlands competitions, creating a comp task began at 5.30 am with a temperature trace. I used to perform this flight each morning in preparation for the day’s task setting. Requirements were: • • Trike • • Instrumentation • • Thermometer • • Note pad • • Mol/Cu chart • • Sensitive pilot The parameters were to record the tempera- ture every 500ft at a climb rate of 500ft/min to a height of 10,000ft, stabilise the thermometer for a minute or two, then glide back to the start point, once more recording the tempera- ture every 500ft on the way down. During the flight, it was important to record each shear layer and note the new wind di- rection in each air mass. This was achieved by allowing the aircraft to ‘weather vane’, i.e., face itself into the wind, due to the differential air pressures over each wing and the fuselage.