Why is it gliders have such long slender wings? Would longer chords
give as effective lift to drag ratios at typical sailplane speeds, is
the wingspan just a more effective way of finding small thermals? My
first thought was a long wing would induce more drag at the many edges,
but clearly that's wrong.

Here's a picturesque way to look at it (which is sure to generate some
heat): the wing works by throwing air down. This forces air up
elsewhere, and the airplane rides on the updraft while it's throwing the
air back down. Other people may say the same thing as "the wing causes
high pressure beneath, and low pressure above... and a vortex is
formed..."; it's the same thing ultimately.

But, the air from below that is trying to get above can either do so by
scurrying out in =front= of the wing as an updraft (where the wing will
meet it and ride the wave), or out the side (making wingtip vortices,
where the energy used to squeeze the air is then lost as far as the wing
is concerned). Only the updrafts in front of the wing help the wing
stay up. The wingtip vortices are lost energy.

So, the longer the span, the greater the ratio of "useful" updraft to
"useless" updraft.

Jose
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