Malcolm Teas wrote:


Both sides are necessary. Single surface winds,(wings?) only found in
Ultralights now I think, are much less effective in creating life, and
they create more drag too.

They definitely create more life. They also create more lift at lower
airspeeds. I fly a Tierra TA that is quite happy at an indicated Hall
airspeed of 18 mph. My Sunburst with the same wing area and a double
surface wing needs about 28 to maintain flight. They both create a LOT of
life for me. Really low and slow I take the TA, for a slightly quicker tour
I use the Sunburst. AHHh, life at 40(mph).