2014年1月16日 Nature / C }6 h; [7 Q* z$ P* Y, _# e) e) @$ D4 g! N8 g! B3 K: u
& x4 a9 ?9 ]9 ~; z0 S1 B4 G/ qNorthern bald ibises flying in V formation during a human-led migratory flight. Some bird species have refined their flying skills to the extent that they can fly in near-perfect V, but why they adopt such a tactic has been a matter of conjecture. One suggestion is that by flying in a V the birds are able to minimize energy costs, and now an analysis of data captured from free-flying migratory ibises suggests that there are energetic benefits. The data also reveal a sophisticated and dynamic process of in-flight control. Birds in the V phase their wing-beats to path-match, allowing a trailing bird to exploit the aerodynamic upwash from the bird in front. A bird flying directly behind, however, flaps with opposite phasing in order to minimize the detrimental downwash from the leader’s wings. All this must require the birds to have developed a range of phasing strategies to cope with the dynamic wakes produced by flapping wings. Cover: Markus Unsöld.7 Z8 Y0 t8 K `0 N* z
: U- O0 b: b9 Y( N% ]' x: U( [ 作者: ljs 时间: 2014-1-19 20:12
) e) @$ D4 g! N8 g! B3 K: u
谢谢，第一次来