Bi-wing glider

Thanks, very informative. Al


wrote in message
oups.com...
Ok, what if one of the wings is a canard? If the elevator pushes down to
support the nose, and a canard lifts, doesn't that make a canard more
efficient?

No. Take a look at the success of Rutan's Solitaire.

The disadvantages with a canard or a tandem wing plane is that it is
hard to use flaps, and to keep the plane pitch stable you end up with a
plane that won't develop the same maximum total lift coefficient as a
"normal" plane because you can never use the aft wing to it's full
potential. This means that you end up having a higher minimum speed
for a given wing area or need more wing for a given minimum speed.
What all this means is that the speed range for efficient operation
will be less than that of a comparable "normal" plane.

You can tune the plane to be efficient at one speed by matching the
airfoils and relative areas and this is how some of the canard
homebuilts manage to show such good cruise performance. But they all
suffer from high landing speeds.

About the only way I see to improve on the standard glider - might - be
to develop a flying wing with some kind of weight shift to increase
it's speed range.

The canard/tandem wing planform does have some advantages for powered
planes but even there I've decided that a negative stagger biplane with
a conventional empenage (Durand Mk V is an example) is more efficient
than a pure tandem wing or canard ..................... and why my Q-2
will fly with a V-tail and flaps if I ever decide to finish it.
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Just my opinion
Leon McAtee