On Sunday, November 17, 2013 10:57:25 AM UTC-5, Waveguru wrote:
I've got a FAI triangle set up where 2 of the legs are on ridges and the 3rd leg will be a down wind leg. Will it be fastest to climb in a thermal to just high enough to fly back to the ridge at min. sink, or would it be faster to thermal higher and fly back faster? Would I set the MacCready setting to the climb I'm achieving in the thermal or what?



Boggs

That's probably not as easy as it sounds. Classic McCready theory would say to climb at whatever rate you get at or near the downwind turnpiont, then fly that setting back to the ridge. Not knowing the geometry/geography of the task, I'm assuming this means you would have to approach the ridge from the lee side and cross back over it to get to the windward side to close the triangle? So, you'll be dealing with potentially strong sink and the risk of smacking into the back side of a very hard object, so you'll probably need to need to start by adding significant safety margins to clear the ridge and account for sink.