"Tony" wrote in message
It seems to me tip plates would remove wing tip effects completely:
airflow would be along the chord all the way to the plate. I'd expect
the tip vortex effects one often sees would no longer exist.

The plate would have to big enough to block most of the tip flow in order to
be effective. That would be a fairly large tip plate and may have other
consequences such as directional stability. I used to tow banners in
modified Super Cibs with tip fences. The fences were about about 4 inches
bigger than the chord profile and did very little in reality.

D.