Not to be a Debbie Downer, but in the previous discussion of glider strobes it was pointed out that battery powered strobes don't have the power to be conspicuous against a bright sky.

Even high-powered airliner strobes don't grab your attention during the day.. There's a 737 that usually flies over my house at roughly 2,000 AGL. The plane itself is easy to see, but at closest approach his wing tip strobes are barely visible during the bright conditions typical of a soaring day.

-John, Q3