dantheman Posted October 13, 2009 Share Posted October 13, 2009 Have seen quite a few posts about how a lot of PPG folk enjoy sticking to the first/last three hours in the day during summer to avoid the thermic stuff. Also how winter flying apart from being a bit chilly is really smooth, here is why....... During the height of summer, at midday in London the sun rises to its maximum "solar elevation" roughly 62 degrees above the horizon At 6:20, three hours before sunset the sun has dropped to 16 degrees above the horizon. During most of December and early January the sun never gets higher than 16 degrees, so the maximum energy from the sun at midday in winter is only as strong as those summer evenings. Cambodia mentioned that he flies after 4pm in the summer, here your solar elevation has a height of 37 degrees, meaning from Oct-Apr the sun is no stronger at midday than a 4pm summer flight, giving him six months of all day flying windows during the colder months. I realise that other factors influence bumpy flights like airmass/ground temps, cloud cover etc etc but its still a very good guide to working out where your thermic comfort window extends to. http://www.timeanddate.com/worldclock/astronomy.html Quote Link to comment Share on other sites More sharing options...
learner_driver Posted October 13, 2009 Share Posted October 13, 2009 very enlightening Dan, I did not know that. also bear in mind that that you will need less solar energy to produce the same lift as in summer, with a colder airmass to heat up. baa Quote Link to comment Share on other sites More sharing options...
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