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But using a real wing is still much better than a model, says Spedding — and
it sometimes throws up surprisingly different results. Previous studies using
brass models had suggested that using swept-back wings helps swifts to boost
lift by generating small vortices in the air-flow around the wings2.
But Lentink's data contradict this theory; his results show that swifts generate
lift more effectively by fully extending their wings.
This information could be used to improve the
design of aircraft, Lentink says. Some planes, such as the F-14 Tomcat, already
incorporate these principles by allowing the wings to sweep back when the plane
is flying particularly fast.
Lentink says that these aircraft designs are
crude compared with what the swifts can do, thanks to the engineering challenges
involved. "The swifts are just better at it," he says, "The
amount of feathers and muscle involved is challenging for us [to imitate]."
Engineers have a lot of things to consider,
Spedding adds. For example, having flexible wings could require extremely heavy
supports, cutting into any gains in fuel efficiency made by the wing shape.
"Aeroengineers tend to look at you in horror when you suggest things like
that," he says.
http://www.nature.com/news/2007/070423/full/070423-7.html