Hi Roger, I can answer that for you as Bob and have already discussed it relating to my 601 build. Apparently, when the air flows over a leading edge that overlaps a trailing edge, a small vortex forms creating a slight disturbance in the airflow. Now obviously this will still happen when the leading edge is fitted under the trailing edge skin, but apparently the disturbance is somewhat less... enough for Chris Heintz to design it this way and I do recall having read him commenting on this somewhere.

You can do it in the reverse manner and some people do, but I have done it this way on my 601 rudder and will do on the wings if that's what the plans say.

Of course, ideally, there would be no join in the skin, but that would be much harder for homebuilders to produce I guess.

I will send you Bob's email address privately, or you can visit his site at www.avtours.com.au

Keep in touch!

Glenn.