Guidelines or formulas for how much water to dump in narrow orweak thermal racing?
The biggest challenge (for me at least) is deciding on the amount of ballast to carry when launching early, when the lift hasn't yet developed to the strength I hope to see later in the day when it reaches its maximum power. Many times I have been forced to "curb my enthusiasm" by dumping part or all of my water to remain aloft, only to curse that decision when the lift peaks midafternoon and I am flying lighter than I want.
Another challenge is trying to figure out what CG range works best for the type of conditions I will encounter. Many manufacturers and pilots suggest about 80% aft in the recommended CG range, but that seems to work best with a climb/cruise ratio of 50%. If I am in strong, streeting lift conditions, I sometimes have about a 20% climb vs. 80% cruise ratio, meaning the drag associated with elevator deflection is much higher during cruise. Drag goes up exponentially as speed increases, and since I spend more time running than circling, the drag penalty is much higher. I hope to be able to quantify these data this year to be able to determine an "optimum" CG point for weak, vs. strong conditions.
And then I will just forget what I learned and do the best I can to make some distance and avoid as much yardwork as possible.
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