Swift wing secrets revealed, according to reports in ScienceNOW and news@nature 25 April 2007.
Swifts are small, migratory birds that spend most of their lives in the air. They can eat, mate and sleep whilst flying, changing, or “morphing” their wing shape according to the speed and agility required. A group of scientists led by David Lentink, an aerospace engineer turned zoologist, has studied swift wings, taken from dead birds, in a wind tunnel and measured the lift and drag on the wings held at different angles and at varying airspeeds.
The researchers found that wings spread straight out worked best for gliding, but sweeping them back at an angle improved their turning ability. This fits with observations of live birds when they are gliding or darting about. The researchers also worked out what speeds that birds could fly to minimise the energy needed to fly. This was between 8-10 metres per second, the speed at which the birds glide as they sleep.
Anders Hedenström, a theoretical ecologist at Lund University, Sweden, who participated in the study, commented: “They have evolved an aerodynamic design for cheap flight.”
Editorial Comment: All known cases of the origin of “aerodynamic design” show that it is not something that evolves by chance random processes. With aircraft you have to get it right first time or you don’t fly at all. The fact that swifts are so aerodynamically versatile in a way that no human aircraft can be, is a reminder that swifts were designed by a much smarter aeronautical engineer than the ones who are trying to find out how they work.
Evidence News, 29 August 2007
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