Minnreefer, your comment in another post, ".... I can't see what my plane is doing as well as when it is closer to the ground, wearing glasses would help, but my eyes are not used to the glasses" makes me wonder if you have a vision problem. If so, I suggest you get to an ophthalmologist and get some good glasses. Your eyes will then serve their purpose if you get good glasses, or proper attention to the eyes. I well know as I spent 25 years going thru different optometrists and my vision was going away far too rapidly. Well, now I have 20-20 in left eye and 20-30 in right eye without glasses. I wear a slight prescription when watching TV, driving, and flying model airplanes to keep the eyes the same. WORKS, and I'm a month away from 72 years old.

Now if vision is NOT the problem, I will say that there are some days when all colors "gray-out" and one has to rely on "where did you come from, where is it going" mostly like what 'stang' said. I try to make all my students use white on one wing surface with a combination of white and black (blue) on the other side. WIDE stripes at a 45* +/- every few inches will help in most conditions. Reds, blues and such are all black at a few hundred feet. In some conditions orange will show up well, but in my 37 years of RC, I have not found better than a wide black-white pattern.

Check the local $ store and you will be able to find some tape (3/4" black electrical tape can be laid 3-4 strips side by side to make wife black stripes) or even colored stick-on shelf paper that can be laid to form the needed colors, or designs. Check with a Pattern Pilot at the field and he will show you how he assures instant recognition. These guys have all the tricks.

Good Luck.