Grey cloudy and still day yes,perfect and not to harsh re sunlight,particularly here.Still hav;nt found the solution for my plane with the high tank and upside down saito but desperation won and i test flew it with a 3500 idle and my buddy lead hooked up to the club genious,it was very comforting.Rearward cg and large control throws on a windy day plus two dead sticks,i gave up when the wind blew the plane over.